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i Maliko, Et Al. vs. Union Carbide Corporation 51 of Third Supplemental Interrogatories /Ul ~'s ^T~ c, <4 *hrtfr ucc 049047 HUMa l VSi OfoluO of 2.( 4, 8W 6W oon \ 1 * u ucc 049049  > 4 A r V-' - Date 2/27 2/28 2/28 2/2* '' -1 i 3/1 5/2 5/2 3/2 3/3 3/3 3/3 3/4 3/4 3/5 3/6 3/6 /' 3/7 3/8 3/8 3/9 3/9 3/9 3/9 3/10 3/10 3/11 3/12 3 ' 12 3/13 , -- ----- t ' ,, :*M 3fV \ - x RESIDUAL VC!l February 22 - March 15t 1975 603 602 601 605 r;04 *302 605 603 601 604 602 606 603 604 601 603 605 602 606 o05 604 601 602 601 603 605 602 606 601 603 602 601 603 Conditions Residual VCl. com Normal stripping while pumping through vacuum stripper at 70*C /6C f Average 1, 504 1,629 1,425 1.017 0 18 1.773 842 1,136 1, 179 1,403 1,077 1,557 1,253 949 917 1,239 Batch vacuum stripped, unknown temp. and time because of bad thermocouple - off-color resin Average 232 178 110 173 var i-:n*. stripped, at 44 to- minutes at 10-1*; inches Mg vacuum. acceptable color resin Average 2 i .1 278 270 191 239 Batch vacuum stripped at 90*C, 30 min.. acceptable color resin Average 69 111 153 173 160 158 83 53 103 91 188 122 ucc 049050 - QSQr BIN DATA OF RESIDUAL VC1 Date 3/13 3/14 3/15 3/15 3/K 3/16 3/16 3/17 3/18 3/18 3/18 3/19 Bin Residual Monomer 606 609 606 603 606 602 603 601 602 601 603 604 Average 946 155 727 735 -90 977 671 930 995 1,847 497 240 687 Stripping Conditions 90* - 30 minutes 90* - 30 minutes 80* - 90* - 30 minutes 80* - 30 minutes 80* - 30 minutes 80* - 30 minutes 80* >30 minutes 80* - 30 minutes 80* - 90* - 30 minutes 90* - 30 minutes 90* - 30 minutes 90* >30 minutes UCC 043051 vs oval monomer ppm Dai'S QSAN Bin Residua: Monomer Stripping Conditions 2/10 2/11 2/11 2 /! * 709 706 707 70* 78 70 185 108 .1 /1 t 2 /1 o 703 2/17 709 2/17 704 2/18 707 2/18 703 2/23 703 2/23 705 2/23 702 2/23 703 2/24 706 t 2/25 2/25 705 411 -0 50 73 104 111 115 122 200 1 12 96 80 156 104 Average 109 QSAL 2/i' 2/ 10 2/20 2/20 2/21 3/9 3/9 3/9 3/10 ~0o 707 702 707 708 408 409 702 705 Average - ) ^ 216 292 277 256 211 280 190 133 231 VSKK Continuous 80*C Ditto Ditto Ditto Ditto Ditto Ditto Ditto Ditto Ditto Ditto Ditto Ditto Ditto Ditto Ditto Ditto Continuous S0*C Continuous 80*C ditto ditto ditto ditto ditto ditto ditto 3/13 3-M3 3/13 3/14 707 704 709 706 603 1,44M 800 1,210 Continuous 75*C ditto ditto ditto ucc 049052 I Bin Data - Residual Monomer PPM 2. Dire 11 in D J^ wr^1 ' , ,* VSKK (continued, 3/14 3/15 3/16 3/16 3/ 16 3 /1 S 7 ' I s 3' IT 3 /19 3/19 3/19 3/20 3/20 3/21 3/21 3/21 707 709 706 708 703 704 , 1i i 70'. 709 706 703 701 704 707 701 Average o 1,418 924 909 846 hOf. !. !1 ;U 1,125 l, n 3 5 i,06 1,102 1. 781 2,01., ?, 514 7S`5 1,189 . Striupin^ Conditions Continuous 75*C ditto ditto ditto ditto ditto dirt.' ciino ditto ditto ditto ditto ditto ditto ditto ditto ucc 049053 . +i uc ***- i internal correspondence CHEMICALS AND PLASTICS T INAMI) L CATtOW Mr. A. A. Peterson Building 114 TEXAS CITY PLANT P. a. (OX 471. TXA* Cl TV. Ttx*( HIM December 11, 1975 coxv to Dr. J. C. Chdty Mr. M. E. Eisinhour Mr. R. L. Fraitz Dr. D. R. Montgomery Mr. R. W. Seller Mr. G. F. Tacquard Mr. R. N. Wheeler - 514 ubjcct Results of B. F. Goodrich Stripping System to Remove Residual Vinyl Chloride from UCC Suspension Resins Dear Adolph: Samples of QSQH-7 and QSAN-7 were supplied to B. F. Goodrich's Research Center. Brecksvllle, Ohio, for pilot plant tests to remove residual vinyl chloride via their patented continuous stripping operation. These samples were obtained from the blow down tanks before vacuum stripping. Both resin samples contain ed residual VCM exceeding 10,000 ppm. These resins were subjected to varying residence times and temperatures at Goodrich In an effort to remove the maximum amount of residual vinyl chloride. Samples were taken at each test condition and returned to Texas City for evaluation. Results of these resin samples after stripping are shown In the attached Table. Reduction of the residual VCM, particularly with regard to QSQH-7, Is considered to be a slight Improvement over the current UCC production. However, the extreme stripping conditions (> 100C) also resulted In severe resin degrada tion as shown by the high yellow factors. Stripped samples of VSJE-10 supplied to Goodrich have not been received. Please let me know If additional Information Is desired. Very truly yours,. / kw Attachment R. M. Arnold UCC 049054 RESULTS OF B. F. GOODRICH PILOT PLANT PROGRAM CONTINUOUS STRIPPING OF UCC SUSPENSION VINYL RESINS TO REMOVE VINYL CHLORIDE MONOMER Resin Type QSAN-7 QSQH-7 Sample Designation 1104 A 1104 B 1104 C 1120 A 1120 8 1120 C Test Conditions (Hinutes/"F) Residual VCM. ppm Yellow Factor 6.4/236 7.4/236 6.9/216 ^ A / , JInitial After Stripping 11,690 ______ 6 * 3 /r 21 . ^ 1.0 7.8 9.0 9.1 5.8/236 6.9/235 6.9/214 20,283 32 >7 n 61 ry 1.0 7.0 9.9 7.2 O <_ O go RHA;kw 12/11/75 i INTERNAL CORRESPONDENCE CHEMICALS AND PLASTICS to (nam*)/ Mr. R. N. Wheeler company Building 189 - Room 301 location SOUTH CHARLESTON PUNT oat* KtotlVtO UC 149- l ----------------------- 3UN 19 ^ N, WHEO-ER. W* P, O. BOX 471. TEXAS CITY, TEXAS 77190 June 13, 1975 ,*v- copy to Mr. M. E. Eisenhour Mr. R. l. Frantz Mr. R. W. Sesler Mr. G. T. Tacquard 3i'jtcT VCM Concentrations in QSAL-7 Slurry Dear Nick: At your request, a limited study to determine the VCM concentrations In the vapor above the suspension resin surge (slurry) tanks has been made. A sample was obtained of QSAL-7 from the surge tank in a glass sample bomb. The sample was placed in an oven maintained at 75C (approximate slurry temperature) and a vapor sample withdrawn after 0, 1 and 6 hours storage for VCM analysis. The sample bomb was filled at 501 capacity. At the time the sample was taken, the stripping temperature for QSAL-7 was 90C for thirty minutes. The resin portion of the slurry analyzed 875 ppm VCM. QSAL-7 samples taken from the surge tank and dryer approx imately one hour after this slurry sample was obtained had the following analysis: Date Time Sample VCM, ppm 6/4/75 9:00 a.m. No. 5 BDT 626 No. 5 Dryer Spot 209 Therefore, during the production of QSAL-7 having approximately 200 ppm VCM, the vapor above the BDT would have VCM concentrations which closely approximate the results from this study as shown in the attached graph. QSAL-7 stripping conditions were changed soon after these samples were obtained so that comparative data was not generated. Please let me know if additional information would be desirable. Very truly yours. /kw Attachment . 'I' R. M. Arnold UCC 049056 I / OCC 0A905S INTERSAl. correspondence RECEIVED MAR - 4 1977 W. R. M. \JC * t CHEMICALS AND PLASTICS TO (NAME) Dr. R. J. Anderson, 312 i 'A' LOMPSHy Mr. M. E. Eiscnhour LOCATION Mr. R. L. Frantz Dr. W,- R.-'Mannino, 511 tnv to Dr . C. E. Moyer M** c. r. Tacuua rd Mr. R. M, Arno Id bill Dr. F. H. Covitz, 312 Mr. S. A. Dickerson Mr. J. B. Hollingworth, NYO (28) Dr. D. R. Montgomery Mr. F. S. Provenzano Mr. R. N. Wheeler, 514 * Suspension Vinyl Staff . O. OK A(, TCU( Cl TV. TtKAI *0 February 23, 1977 Test Program To Reduce RVCM Levels in Suspension Resin Slurry The recently published EPA regulation concerning vinyl chloride emissions included a requirement that vinyl resin contain less than 400 ppm residual vinyl chloride monomer (RVCM) when it leaves our blowdown tanks (BDT*s). An intensive effort is underway to accumulate the necessary data and define a program that will allow us to meet this new regulation. The purpose of this letter is to summarize the work completed to date and to outline the work re maining to be completed. The data first collected on RVCM levels of the various Suspension resins showed wide scatter and could not be correlated with any of the stripping conditions employed. This data was obtained from spot samples after the slurry had been stripped in the BDT and as it was being pumped to the dryer building. This scattered data resulted in a change in the sampling method from spot samples to continuous sampling during the stripping and pumping operation. Analysis of-the data from continuous sampling (see Figure I) resulted in two major observations: 1) that suspension homopolvmer could^fonsistontly be stripped with existing equipment and pro- ce3ure&_to levels less than 400 ppm RVCM, and 2) that re-pressuring 'the jDT^s. with the "15-lb. vent header" resulted .in.Ia.7signxi.c,ant Increase in the RVCM level to well above the 400 ppm level. Co- -polyrr.er resin slurries at this time were still above the 400 ppm level after stripping exi.-tinq equipment and procedures, but also showed the same trend of increasing RVCM levels while pumping under the "15-lb. vent header" pressure (see Figure II). uco 04905Q t # w s\v A 2. At this point two tests were performed to determine if the low RVCM levels co'ild be maintained if the slurries were pumped with out ro-pressiring with the "15-lb. vent". The first test was carried out ohile pumping the slurry from the BDT to the dryer building undc-r vacuum :cr.d ; t . c :.s . Those results shoved, .that, by maintain!nr a vacuum on the jl, 1.the RVCM.1eveIs would continue to cfSpUdiiri'ng pimping. However, this pumping procedure resulted in mere than doubling the pumpout time of the BDT. Since the BDT's are presently production limiting, this pumping procedure was felt to be an unsatisfactory solution to the increasing RVCM problem. The second test involved re-pressuring the BDT after vacuum with _nitroqeh. "These" results (see rigure"`I)"wereHalso very good with the RVCM levels remaining fairly constant below the 400 ppm level. Again, however, problems arose that involved limiting production capacity. The nitrogen in the_system added two problems: 1) the volume of nitrogen had to be' pumped through "'the munumer- recovery system which is already loaded and this resulted in an increased stripping time, and 2) the excess nitrogen caused the MEK absorber to lose efficiency in the recovery of VCM from the off-gas recovery system. While both of these tests proved that re-pressurina the BDTlA^with,^he "15-lb/ vent header" was'the cause' of"the increasing RVCM levels, they did not provide satisfactory alternatives at the "time. ~ - Another concern that arose during these early test^was color degra dation of the resin. While we had shown that most all homopolymers could be stripped below the 400 ppm level we were still concerned with copolymers. We felt that temperatures above those presently being used (85C) would be required to sufficiently strip copolymer slurries but that these higher temperatures would cause resin color degradation. Two suggestions were made to try to prevent this color degradation and lower the RVCM levels to less than 400 ppm: 1) that the slurry be cooled immediately after stripping at the high tempera tures (90-95*0 and~2) that sodium nitrite be used to "kill" the 'polymeritAtiori "in .the autoclaves after the-desired, termination point ""Had been reached. The first suggestions was based on"*long experience "Wrat showed resin color degradation was a function of total heat applied to the resin. By raising the stripping temperature but shortening the time at temperatures above 60C, the total heat applied to the resin could be lowered and should not cause a color degrada tion problem. The second sugq< stion resulted from R fc D work which showed a lower color degraiati >n rate for resins "killed" with sodium nitrite than for those :*.ot treated. Since the only equipment w.- in the production unit that could be both heated and cooled was tin autoclaves themselves, it was de cided .to test the first suggestion of cooling the resin in an auto clave. The autoclave D-3 was chosen for the test since it was UCC 049060 : r. - irons:. r. a _:rrv equipped with steam heatup. One test was conducted in January but enough data was not collected. Since the samples were more than twenty-four hours old before they were delivered to the Lab. no RVCM levels were measured. However, the color index measured ir'ter striopir.i- for minutes w<is enlv 2.9 which was ncouragin::. Th.s tost wu;: ter forme.: cn CSAH resin, not a copolymer, because the steam heatup wa:- only connected to D-3 autoclave. We had hoped to obtain enough nformatior. from testing QSAN resin to indicate if test cn copolymers would be worthwhile. Again, however, this test ran into trouble as the steam heatup piping was dis connected and lost when contractors made new tie-ins for the steam heatup system on the North and East lines. This testproaram has, therefore, been temporarily discontinued until the steam injection system is* complete. -- We then developed a program to test the effects of sodium nitrite addition on color at a temperature of 90C on copolymer resin. These tests were conducted in existing production unit equipment with VSJE resin. R fc D test had shown some problem with the addition of sodium nitrite to slurries containing other color stabilizers used in the unit such as EPO, Bis-Phenol A, and Irganox 1076. These were eliminated from the VSJE recipe to prevent this color formation problem between these stabilizers, and sodium nitrite. ?c date four to* c; have beer. e mu jcced. The first was somewhat of a failure as the operator added Bis-Phenol A to the BDT and the resin turned green. This did confirm/'however, the problems noted in the RT"D test. The RVCM level on this batch did look promising with low reading of 30 ppm. The second test was more closely supervised and no green resin was noted. The color readings on this batch were very promising with essentially little change from beginning to end of the stripping operation which cook over two hours. The initial color on this batch was somewhat high at 7,8, our normal range is between 4.0 and 8.0 for stripped batches at 85C. RVCM levels for this batch were not very good with low reading of only about 500 ppm. Careful examination of those two test revealed a' difference in stripping procedure which may be significant. The first batch was heated to 90C after being placed under vacuum and the second was heated to 90C before vacuum. Since little heat is lost in this operation, this indicates that steam was being vigorously sparged into the slurry while under vacuum on the first test (see Figure III) but this did not iccur on the second test (see Figure IV). With this observation in run.; vur third and fourth test/were planned to try to dupl.tnte the tii:;*. -.wo tests. Data from these tests could then to used to determine if vigorous steam sparging during vacuum caused a significant crop in RVCM levels. Results of the third test supported this idea with RVCM levels down to 10 ppm being UCC 049061 * ns i it ^ ^ Qiii *s. ^1 in Suan:r,Jicr, Posm s 4 noted. However, color index reading from this test were not as good with the color rising from_ap_. initial .4.0 to 6-0 after two ^hours^ While RVCM during the fourth test dropped to a low of about SO ppm, the overall data indicated that RVCM levels did not, drop as fast as those during vigorous steam sparging under vacuum. Comparison of the data shewed hat with vigorous steam sparging under vacuum the RVCM levels were between 2C0 and 400 ppm only ^30 minutes after starting vacuum (see Figure III) whereas without vigorous steam sparging the RVCM levels were between 800 and 1,000 ppm at thirty minutes (see Figure IV). Additional tests to be conducted concerning this procedure will be outlined later in this letter. During this same time period a couple of other ideas were tested wh"ich_related to RVCM levels. One was trying to re-pressure tHe 'BDT's with steam. This proved unsuccessful after thirty minutes and the idea was abandoned. Another idea was to pump copolymer slurry from the BDT into the foam trap where it would enter the top of the tank through a sparger. This, it was hoped, would give better liquid-vapor contact and thus help VCM removal. Results from two tests were not very encouraging. The RVCM levels were somewhat lower than those from normal operation (400 to 500 versus 500 to 600) but not low enough to meet EPA requirements. Therefore, this idea was not considered pratical at present and no futher test are scheduled. Another area that was tested during the very early stages of this study was the effect of polymerization termination point on RVCM levels. However, the data collected was so scattered that no con clusions could be reached, with the encouraging results that have recently been obtained it is hot felt that additional tests are necessary at this time in this area. The following is an outline of additional tests that are currently being considered in the study of RVCM levels: 1. Sodium Nitrite Addition -- A major test of the effect of sodium nitrite on copolym r '"color has been postponed since .the Lab color_analyzer is, presently out of service. As soon as this analyzer is functional we will proceed with a test program to produce about two van boxes of copolymer that has had the poly merization terminated with sodium nitrite. This material will Le isolated from other copolymer material produced at the same time to help determine any differences in the two resins. The rosin terminated with sodium nitrite will be stripped at 90 - 95C in the BDT's versus 85C for . the other material. These materials will be dried on separate dryer systems but at hopefully similar conditions. ucc 049062 Test Program To Pc-iiuco RVJM in Suspension Resin Slurry .Id 5. Since this test will probably be conducted during the VSKK run, we will not only collect data on color index and RVCM but also haze. Completion of th^s test is expected by March 4, 1977. --*""" ---- * 2. Revised Stripping Procedures (With Pumpout Under Vacuum) The normal steam stripping procedure,for resin slurries w~lT~be"revised to provide for ~yIqotous~"T\eam sparging While under--vacuum conditions^ Incoroorated with this different steam stripping procedure will be instructi ns -cp pump the slurry"frotrT the~BfiT~tO~thenrorgg taftX Under y^cuum, not with re-pressurizaTXon `from fKe "1^-lb." vent header*. The-purpse"OF"fhis"fest will be to determine how fast RVCM can be stripped from the slurry to a level below 400 ppm average while still maintaining an accept able color index. Wo will also determine what production rate is lost, if any, by pumping the BDT's out under vacuum. This test will be conducted on only one autoclave line at a time. This will allow us to develop the best stripping cycle under these conditions for each resin types that will meet the EPA regulation. Completion f these tests is expected by March 11, 1977. 3. Revised Stripping Procedures (With Pumpout Under Pressure , Should the results from Step 2 show that the production lost with pumping under vacuum is unacceptable we will proceed with these tests. This procedure will be basically the same as Step 2 but will provide for pressuring the BOT with nitrogen prior to pumping. Again, this test would be conducted with only one line at a time initially. After each line is tested separately, all three lines will be tested simultaneously to determine if any problems exist while operating all three lines under this procedure. Completion of these test, if required, would be March 18, 1977. ------------- 4. Steam Stripping Followed By Cooling No tests are planned at this time. ucc 049063 6 While not all the data collected thus far has been presented in this report, an attempt has been made to summarize all the important work completed in this study to date. Any questions concerning this report or request for additional data should be directed to me. '/our comments about any facet of the test program or con clusions reached from the data are also welcomed. Many thanks go to Steve Dickerson and his Lab Technicians for their help in collecting and analyzing the samples. Sincerely. KEB/st Attachments K. E. Bowen ucc 049064 'I80& l # ie#0 T--L Ov> 100 ? -- A*. irtEOT (',3+ Vuto ftnC) ---------- * -- 3~. ia;n * iwt (ic* v**- (**) ' .+ F-U U<M___ ' .-' ; -!_-i. _______ .J. -Ift ^0 0)0 2 SO 40 tt 0* 10 ucc 049066 7CA0 Ctao 5oo l&Q oft 600 0o t 0 -to KjVcm \lVJLr Txw\e 4 I G C) ucc t 049069 BUSINESS CONFIDENTIAL PROJECT REPORT SUSPENSION ''INYL RESINS RETARDATION OF COLOR FORMATION AT STRIPPING TEMPERATURES AUTHOR: D. R. Montgomery SUPERVISOR' C. E. Moyer, Jr. oat* May 4, 1977 project Mai 216B12 pile mo.> 2 3577 SUMMARY A series of tests have been run to define color stability of PVC resins as a function of time and temperature. These tests were run to simulate slurry stripping conditions plus surge tank residence time in order to find a way to maintain acceptable color while mini mizing residual vinyl chloride monomer (RVCM) in suspension resins. A number of additives were evaluated to see if any of them could stabilize PVC resins to the extra thermal abuse needed for better stripping. The best of these potential stabilizers was found to be sodium nitrite. It has been found that its addition to copolymer slurries (VSJE and VSKK) stabilizes them sufficiently that they can be stripped at temperatures 10-15C higher than normal with color comparable to conventional resins. These results have been verified in plant trials and resulted in resins with satisfactory color and a significant reduction in the RVCM in the product. Resins from these plant runs have been shown to behave normally in typical enduse formulations. It has also been found that the addition of other stabilizers (such as Mark C, Mark M, or Bisphenol A) to a sodium nitrite terminated slurry results in significantly accelerated rates of color formation due to reaction of the excess nitrite with the other stabilizers. Obviously cross contamination of sodium nitrite containing slurries and these other materials, particularly Bis A, must be avoided Several potential problems with full scale use of this procedure are recognized and further work is planned. RESEARCH AMD DEVELOPMENT DEPARTMENT CHEMICALS AMO PLASTICS UNION CARRIOE CORPORATION TEXAS CITY, TEXAS I l UCC 049070 Project P.eport 2. INTRODUCTION The elevated temperatures required for effective stripping of unreacted monomers from our suspen sion copolymers, combined with the residence time in the surge tanks and the additional heat during drying, has historically given us trouble with excessive color formation. The recently issued EPA regulation governing vinyl chloride emissions requires a maximum of 400 ppm VCM (calculated on a contained dry resin basis) in slurry leaving the blowdown tanks (BDT). The regulation does allow averaging over all suspension resin production on a twenty-four hour basis. Our copolymer resins (VSJE and VSKK) have very low porosity and are therefore the most difficult resins among our major products from which to strip VCM. Unfortunately, they also have the poorest color stability against thermal abuse. Consequently, we have been unable to utilize the rigorous stripping temperatures that are required to achieve low VCM levels within reasonable times because of resin color limita tions. Analyses of RVCM on BDT samples show large fluctuations, ranging from a few hundred to over 10,000 ppm. (Recent data have shown BDT RVCM to be a strong function of when the sample is tak n.) Analyses of dried resin in the bin samples for the first three month of this year indicate an average of approximately 1,200 ppm for VSJE and 1,800 ppm for VSKK. The dried resin RVCM must be lower than the BDT values; a reasonable estimate for an average value of the latter is probably 2-3000 ppm. Certain modifications to the stripping procedures are being investigated which will help, but we also obviously need to be able to utilize higher stripping temperatures if we are to meet the 400 ppm with a reasonable cycle time in the BDT. RESULTS Color kinetics runs were made at 92C; a more detailed explanation of the procedure followed and the technique used in evaluating the results is given in the Experimental Section. The primary criteria for comparing results was d(YI)/dt, the change in Yellow Index per hour. The bulk of the work was done with VSJE slurry"and unless indicated otherwise, the results reported are for VSJE. Several potential stabilizers were screened and compared with unstabilized controls. Representative values for d(YI)/dt are given in Table I, along with a tabulation of the final YI obtained after 5% hours. The most striking results were with slurries which had been killed with sodium nitrite at the termination point, which gave d(YI)/dt considerably less than 1 and final YI *10. Other runs with NaNO* under slightly different conditions actually gave values as low as 0.1 and 6.6, respectively. The results compare quite favorably with the control, 2.2 and 14+. The run containing Irganox 1076 (an antioxidant) was virtually superimposable with the control. Inclusion of EPO (epoxidized soybean oil), used routinely in Production as a stabilizer, actually increased d(YI)/dt to 2.7. This rather surprising result was later duplicated with a completely different batch of slurry. Post-addition of Thermolite 25 (a commercial organo-tin vinyl stabilizer) and Bis Phenol A (used by Production as a short stop and possible stabilizer) gave modest improvements to 1.7. Mark M (a commercial Ba/Cd vinyl stabilizer) gave some what b tter results, 1.2. Mark C (an organo phosphite ch lator) ucc 049071 Project Report 3. showed substantially improved results initially, 0.4, but then had a break to a higher rate, 1.0. The results of attempts to combine the NaNOa treatment with some of the other moderately effective stabilizers/ looking for an additive or synergistic effect, were disappointing, An adverse interaction was found with all of the additives tested except EPO, and the rate of color formation became quite high, as illustrated in Table II. This extreme color was subsequently shown co be due to reaction of the excess of aqueous NaNO* (or HNO*-the slurries normally exhibit a pH of v4) with the stabilizers.' See Table III for the results of heatinq aqueous NaNOa with some of the other additives. Dry resin from NaNO--treated slurries shows no adverse interactions with the usual stabilizers in end-use tests.*'1'* The possible effect of small amounts of iron was of concern since the Production blowdown tanks are stainless steel. Add d ferric iron at 250-500 parts per billion was shown (Table IV) to have an adverse but not catastrophic effect on the rate of color formation both with and without NaNOa. The presence of a 1 w con centration of disodium ethylenediamine tetraacetic acid (Na*EDTA) moderates but does not eliminate this effect. Addition of NaNO* at the termination of the polymerization was found to be effective at slowing color formation in VSKK also, as shown in Table V. The color retardation was similar to the VSJE results, although not quite as pronounced. QSAF is the most difficult to strip and was therefore selected to illustrate the benefits which might be possible with the homopolymers. The results, shown in Table VI, indicate a positive effect but since the "control" rate is lower, the benefits are also less spectacular. The initial rate in the NaaEDTA run was comparatively high but it leveled off quickly and the final * color was only 6.5. Polivic S202 is a potential additive to increase porosity4 and was checked for possible adverse inter actions; obviously none were found. The amount of NaNOa added to a slurry influences the degree of stabilization achieved although this is not a spectacular effect. Figure 2 shows d(YI)/dt vs NaNOj concentration for VSKK. These data represent three separate polymerizations in which varying amounts of NaNOa solution were added to the autoclave at the end of the polymerization with duplicate color kinetics runs on one of them. The average final color (5h hours) was 9.5. Data on a variety of VSJE slurries shows a large amount of scatter in plots of d(Yl)/dt vs NaNOa concentration although the general trend is toward a stronger effect at higher concentrations. In retrospect there are other factors besides NaNOa concentration per se that appear to affect its effectiveness at retarding color formation. These factors were not recognized at the time many UCC 049072 p t* ^ 4. of the experi;:r.zs were designed and thus net adequately controlled* Specifically, acidity of the slurry is of over riding importance. A sodium nitrite treated slurry lost over half of its apparent stabilization when it was neturalized to pH*7 with NaHCO* before heating. Comparative data are given in Table VII. A rationale for this effect will be offer ed in the discussion of mechanistic interpretations. Aliquots of the same slurry were run at 92C, 80C and 70C for both VSJE and VSKK to derive an activation energy for the color forming reaction. The data are tabulated in Table VIII and plots of ion (dfYI) -'dt) vs 1/T are given in Figure 3. Derived Ea * s are '3 and 33 kcal/mcle, respectively. DISCUSSION Mechanistic interpietations Several tentative conclusions as to the mechanisms of color development and its retardation can be drawn from the results described above. Further confirmation will be sought for some of the key points. The rate of color development at 70-92C, as measured by d(YI)/dt, gives reasonable results when treated as a pseudo first order reaction. This does not mean, however, that the actual reactions taking place which give rise to the color are necessarily first order. The commonly accepted source of color when PVC is heated is conjugated carbon-carbon unsaturation due to dehydrochlorination along the backbone of the polymer. On this basis the "percent completion" of the total potential reaction is extremely low and the normal treatments of kinetic data which require several half-lives of tho reaction are coviously rv't applicable. Also, YI is not necessarily a linear function of the extent of dehydro chlorination. Even with these limitations several interesting conclusions can be made. The firmest conclusion at this point involves the basis for the pH effect on the effectiveness of NaNCa as a color re tarder. This is almost certainly a matter of the concentration of a species which can penetrate the resin particles to where the pertinent reactions are occurring. Nitrite ion per se should be transported very inefficiently, at best, into the resin particle from an aqueous medium. On the other hand, HNOa (or nitrogen oxides derived from it) should have a much improved rate of penetration. Calculations indicate addition of 0.003 moles/liter of NaNOj to an unbuffered pH=4 slurry would result in approximately 3% hydrolysis with a HNO* con centration of 8.7X10"' and pH=4.9. If this slurry had its pH raised to 7, the HNO* concentration would drop to 6.7X10"'. One would then conclude that the only reason the neutralized slurry retained even as much stability as it did would be because it had existed us an acidic slurry with HNOj in it for a considerable time before the neutralization and HilOa in part ially effective concentration had already penetrated the resin IJCC 049073 Project Report 5. and was not completely neutralized. This HNOj-as-effectiveingredient interpretation is consistent with reports that NaNOj is ineffective as a 'hort-stop reagent for those who practice a buffered polymerization. As a corollary to the reduced effectiveness in neutralized slurry, if the pH were lowered to 3, the same amount of NaNO* would be 28% hydrolyzed with a HNO* concentration of 8.3X10~`'. Alternatively, only about 5% as much NaNO* would have to be added to give the same effective HN03 concentration in a pH3 slurry as compared to a pH4 slurry. For example, if the slightly lower pH could be tolerated, addition of 2 lbs of 3j>% HC1 (appropriately diluted) and 0.5 lb of NaNOj per production batch should give approxi mately the same stabilizing effect as the 10 lbs of NaNOa per batch used in the plant tests. The same principle should also apply to the emergency short-stop procedures. It should be noted, however, that acidified solutions of NaNOa could probably not be made up in advance and stored for extended periods of time because of the instability of nitrous acid. The importance of pH was not recognized early in the experimentation described above, therefore was not controlled, and likely accounts for much of the variability observed when attempting to correlate NaNOa concentration with d(YI)/dt. The fact that the rate of observed color development de creases with time within the frame of our measurement even though the percentage loss of HCl is very low suggests that some species is present in low concentration which is substantially more reactive than the bulk of the resin and that this con centration does decrease significantly. It would then be this reactive species which must be intercepted to provide color stability during our stripping and drying operations. The mechanisms of thermal degradation of PVC and of its stabiliza tion have been extensively studied for many years and the literature is replete with conflicting theories. For a recent review with extensive references, see for example Reference 5. It is obviously beyond the scope of this work to settle these controversies; I can only speculate based on what I observed. The fact that HNO* is a very potent retarder for color develop ment strongly suggests that a radical is involved since nitrite is a potent free-radical inhibitor and is in fact used in the suspension vinyls unit to kill "hot" reactions. The radical could be involved in the propagation of the dehydrochlorination, as espoused by Gupta and St. Pierre*, or, alternatively, the initiation of the reaction could involve primary radicals generated from the residual peroxide which is present in the resin. The residual peroxide could be an appropriate species which is present in low concentration and would disappear at a significant rate at the temperatures utilized. The 20 kcal activation energy observed for the overall color formation process is consistent with usual values for organic reactions7: free-radical reactions in general would be expected to be somewhat higher*. Attempts to derive an entropy of activation for further information as to type of reaction were unsuccessful, since such calculations are dependent upon ____________________________________________________________ ___ ucc 049074 - ------ifCI e n. arso-ute v'liu-.: r; available m this c:.?o the magnitude zf whion measuring device. :: :s constant , and nil that is irit-orjor rate coefficient, croon*: cr. the unit? used by the The green color observed when Bisphenol A and NaNO* are used in the same slurry is likely due to acid-catalyzed nitrosation of the phenolic ring as follows: OH OH o CHj- c-ch3 fS It OH i .K '! T OH *;----- , ,' T c h - c --CHi Vl| OH Close analogies exist m thu literature, e. g., the reaction with 3-naphthol.10 ir !I Metal lake of nitroso-B-naphtgreen with M=Fe The specific reactions between NO* and Mark C and Mark M are not so obvious but it is clear that all of these highly-colored re actions involve the excess (HNO:) present in the water and there are not sufficient residues on the resins after drying to cause any problems. tJCC 049075 A Report: 7. The destabilizim: effect of EFO at 92 , although dis turbing, is not necessarily inconsistent with its presumed stabilizing effect during ambient temperature storage. The author has had previous experiences in solvent vinyls where propylene oxide definitely stabilizes color of varnishes at ambient temperatures but ethylene oxide in a solution heated at 60C caused an increase in color formation. Epoxides are frequently used as vinyl stabilizers, presumeably functioning as HCl traps. However, the epoxy group possesses considerable basicity and it appears likely that at higher temperatures it may function as a strong enough "pull" to accelerate the dehydrochlcrination reaction. Practical Applications The laboratory studies have shown that addition of NaNOj to copolymer slurries after the prescribed terminat:on pressure drop has been reached will provide a significant retardation in the rate of color development at stripping temperatures. This increment of stabilization can be utilized either to provide improved color at normal stripping temperatures or to allow higher temperatures, and thus faster removal of RVCM, with comparable color. In cither case no contact of the nitrited slurry with Bisphenol A can be allowed because of the side re action leading to a green color. The NaNO* can be used in combination with EPO if this is felt to be desireable for color stability during dry resin storage, although the color generated during stripping with EPO will be slightly higher than without it. (The latter statement holds whether NaNOa is used or not.) Low concentrations of NaaEDTA can also be included in the poly merization without adverse interaction with the NaNOa. The nitrite treatment is mere effective in a "normal" moderately acidic reaction slurry (pH v4) and loses much of its benefits in a buffered or neutralized recipe. It would be equally effective at reduced concentrations in a more acidic slurry, e.g., pH v3. Short term trials have been made at the production unit with both VSJE and VSKK. Representative data from these tests are given in Tables IX and X. (Data courtesy of Mr. Steve Dickerson.) These tests demonstrated clearly that significantly higher than "normal" stripping temperatures can be utilized while still maintaining good resin color, if the slurry is treated with NaNOi. As anticipated, the RVCM levels drop much more rapidly at the higher temperatures. Resin from these tests was recovered and subjected to several end-use tests. In all cases it was found to be indistinguishable from "normal" resins.1/a'* It is therefore recommended that an extended plant trial be undertaken for a more comprehensive evaluation of the benefits which can be derived from this technique (as well as a reading on the serious ness of some potential problems). During this trial, the entire copolymer line should be run on the test, to avoid any cross contamination. The test should be of sufficient duration to obtain reliable answers to questions of optimum conditions and procedures in the production equipment and what quality (RVCM vs color)of resin can be produced under our best currently avail able technology. In regards to timing, it might well be desireable ucc " 049076 ?T or t 8. _o wait until the new trtnsfor system from the blowdown tanks to the surge tank is available on the North line, to allow routine pumpout under vacuum without suffering a loss in capacity. Several production-related problems remain to be answer d. 1.) Bird effluent water is normally used to rinse the autoclaves between batches. If we run NaNOa routinely on one (or more) lines, will we see retardation of subsequent poly merizations due to traces of NaNO* in the rinse water? 2.) Nitrites in the water to the waste treatment plant could potentially be a probien. The concentrations that would be present wcuici be extremeLy lew ar.d should r.rt be a significant hazard. However, we intend to pursue this point in detail with the EP Department. Experimental The resin slurries for the tests were prepared in the Suspension Vinyls Pilot Plant. Some of the stabilizers test d were added to the initial charge (if normally' employed in that manner), some were added to the autoclave after the polymeriza tion was completed, and others were added to the slurries in the laboratory. All slurries were stripped thirty minutes at 85C in the Pilot Plant blowdown tank, then portions were saved for subsequent laboratory experiments. The color kinetics experiments were carried out in th laboratory in a jacketed resin kettle equipped with an agitator and a bottom stopcock for periodic withdrawal of samples. Wat r was heated in an auxilliary kettle and circulated through the jacket. Most of the experiments were run at 92*C slurry tempera ture, the maximum at which we could conveniently control. The apparatus was glass except for the agitator which was stainless steel. The procedure followed was to preheat the jacket water, then add the slurry (approx 2700 g) to the kettle. The first sample was taken when the slurry reached 80C (about forty-five minutes after heating started). The slurry reached the control temperature of 92C in about another 20-25 minutes. Subsequ nt samples were taken at intervals for a total of 5% hours. Th extended time was intended to simulate the thermal exposure production resin experiences in the blowdown tank plus the surge tank. The resin was recovered from the samples by filtration and dried in a circulating air oven at 40-45C. The drying op ra tion did not significantly affect the color of the resin. The color of each sample was then determined with the Gardner XL 20 Colorimeter. This instrument shines white light on the sample, then measures green, amber, and blue components of the reflected light and computs a composite value called the "Yellow Index" (YI). This number is basically a measure of the yellowness of the resin although other colors do influence it. UCC internal specifications call for a 10 max YI for copolymers. UCC 049077 AA.l Project P.ercr 9. ?.u.e results were evaluated by plotting VI vs time. These plots exhibit reasonable straight line characteristics for the early points (up to 0-150 min), before tending to flatten out at long times and/or high YI. The slope of a best-fit line through these early points, d(Yl)/dt, units=changc in yellow index per hour, was taken as a measure of the rate of color formation for purposes of comparing runs. Figure 1 illustrates typical plots. The final YI's after 5% hours are also reported in the tabulated data, since the ultimate color at the end of processing is the important practical property. Conclusions and Further Recommendations The addition of sodium nitrite to compolymer slurry provides a remarkable retardation of color formations at tempera tures useful for stripping residual monomer from the resin. Specifically, we should be able to raise our stripping tempera ture by as much as 10C (e,g.r from 80 to 90) and retain as good or better color as we currently get. Continuation of plant evaluation of the procedure is recommended, as outlined above. Additional laboratory work is indicated to clarify several points regarding the mechanism of stabilization. a.) Spectral examination of the resin to attempt to identify the chromophore. b.) Test other free radical inhibitors to see if they provide substantial color retardation. c.) Explore more fully the effect of pH upon nitrite stabilization. Acknowledgements The kinetic runs were carried out by H. R. Nowlin. Color measurements were made by S. A. Dickerson. Polymerizations were done by D. W. O'Daniel. Their assitance is gratefully acknowledg ed . Bibliography *S. A. Dickerson, letter dated February 2, 1977, to D. R. _ Montgomery, Subject: "Color Development of NaNO* Killed VSJE in VAT Application." *R. P. Braddicks, personal communication to D. R. Montgomery, March 3, 1977. 3R. M. Arnold, letter dated March 18, 1977, to R. L. Frantz and D.R. Montgomery, Subject: "VSKK-10 with NaNOa Evaluations." `D. R. Montgomery, "Suspension Vinyl Resins:Evaluation of Polivic S202 for Enhancing Porosity," RS.D Project Report, File No. 22776, dated January 26, 1977. UCC 049078 10. SW. H. Starnes, Jr., Polym. Prepr., Am. Chem. Soc., Div. Polym. Chem., 18 (1) , 493(1977). *V. P. Gupta and L. E. St. Pierre, J. Polym. Sci., Polym. Chem. Ed., 11, 1841 (1973). 'See for example, Glasstone, Elements of Physical Chemistry, D. van Nostrand, 1946, p. 651 or Feiser and Feiser, Advanc d Organic Chemistry, Reinhold, 1961, p. 23. Mine, Physical Organic Chemistry, McGraw-Hill, 1956, p. 90. 'J. ,T . Bunnett, "From Kinetic Data to Reaction Mechanism," Chapter VIII from Investigation of Rates and Mechanisms of Reactions, Part I, 3rd Ed., E. S. Lewis, ed., Wiley Inter science, 1974, p. 405. 1R. Q. Brewster, Organic Chemistry, Prentice Hall, 1948, p. 719. /kw Attachments 10 Tables 3 Figures Manuscript Date: April 7, 1977 Revised: April 20, 1977 D. R. Montgomery ucc PRIVELEGED DOCUMENT Bates number has been skipped ucc 04908 memorandum EVALUATION OF 8. F. GOODRICH'S CONTINUOUS STRIPPING TECHNOLOGY FOR PVC RESIN SLURRIES by %t INTRODUCTION W. R. Manning 12-20-76 This memorandum presents for record purposes an account of the evaluation that was made by Union Carbide in late 1975 and early 1976 of B. F. Goodrich's technology for continuous stripping of PVC resin slurries. The memorandum com* prises a main section and four appendixes. The main body describes the maj r steps in the evaluation and presents the conclusions that were reached. The appendixes give pertinent details about each of the major steps. DISCUSSION In August of 1975* Dr. A. B. Steele, Operations Manager for Suspensi n Vinyl Resins, received a technical bulletin (copy attached as Appendix A) from Mr. Arthur L. Hastings, Licensing Manger for B. F. Goodrich Chemical Company, outlining a new continuous PVC slurry stripping process developed by Goodrich, Such a process was of possible interest to Union Carbide, as well as other PVC manufacturers, as an aid in complying with OSHA and proposed EPA regulations on the amount of vinyl chloride monomer that could be left in PVC resins or emitted to the environment. After a secrecy agreement was executed between B. F. Goodrich and Union Carbide, Mr. A. A. Peterson and Dr. W. R. Manning visited the Avon Lake, Ohl plant of B. F. Goodrich on September 9, 1975 to receive additional details about the process, and to discuss the terms and conditions under which Union Carbide might acquire a license to use Goodrich's process. A copy of Mr. Peterson's report on this visit Is also attached. (Appendix B). Pursuant to Goodrich's offer to run samples of Carbide resin slurry through their six-inch, eight-tray pilot plant column to predict operating conditions and results for a production-sized column, we sent 55~9al1on drums of three resin slurries from our production process: QSAN Homopolymer Resin QSQH Ethylene-Modified Resin VSJE Vinyl Acetate Copolymer Resin UCC 049083 2< t The QSAN homopolymer resin and the QSQH ethylene-modifled resin were run successfully in Goodrich's pilot-plant column, and samples of th stripped resin were returned to us. According to Goodrich, the VSJE vinyl acetate copolymer could not be run because of excessive foaming, (it should be noted that Goodrich developed their stripping technology primarily for homopolymers; they do not manufacture vinyl acetate copolymers.) The results of our evalution of the stripped samples of QSAN and QSQH returned by B. F. Goodrich are shown in Appendix C (letter to A. A. P terson from R. M. Arnold, dated December II, 1975). Briefly, the results showed that the Goodrich process achieved little or no improvement in residual vinyl chloride over our own batch vacuum stripping technology, and the resins stripped by the Goodrich process were much more highly colored than those from our process due to the heat-abuse of the resins in the Goodrich process. CONCLUSIONS The results of the B. F. Goodrich stripping tests were reviewed by the Vinyl Resins Operations Team at a meeting in Texas City on February 18 and 19, 1976. The team concluded that we should not pursue our investigation f the 6, F. Goodrich process any further, because: 1. We were achieving low residual monomer on homopolymer with our batch vacuum stripping process, without excessive heat abuse of the resin. 2. Copolymers are even harder to strip than homopolymers (except low molecular-weight homopolymers) and Goodrich had been unsuccessful in running our copolymer In their pilot unit. 3. Goodrich did not seem really eager to license their process to us, as indicated by the slowness with which they provided results of their tests to us. The tests were run between November A and November 16, 1975* A formal report, dated December 28, 1975, was not received by us until February 25, 1976, and then only after a telephoned request on February 13. 1976. A copy of this report is attached as Appendix D. W, R. Hanning 12-20-76 ucc 049084 ucc 049085 7V* INTERNAL CORRESPONDENCE CHEMICALS AND PLASTICS to `HtMfi Mr. A. A. Peterson </.'v#ARv Building 114 TEXAS CITY PLANT i i La Aha, C_ uc . O. BO* 471, TIM* CITY. TIM* 770 December 11, 1975 COP* V) Dr. J. C. Chaty Mr. M. E. Elsenhour Mr. R. L. Frantz Or. D. R. Montgomery Mr. R. H. Sesler *u*jict Results of B. F. Goodrich Stripping /e Residual Vinyl ICC Suspension Resins Dear Adolph: Samples of QSQH-7 and QSAN-7 were supplied to B. F. Goodrich's Research Center, Brecksvllle, Ohio, for pilot plant tests to remove residual vinyl chloride via their patented continuous stripping operation. These samples were obtained from the blow down tanks before vacuum stripping. Both resin samples contain ed residual VCM exceeding 10,000 ppm. These resins were subjected to varying residence times and temperatures at Goodrich In an effort to remove the maxlnum amount of residual vinyl chloride.. Samples were taken at each test condition and returned to Texas City for evaluation. Results of these resin samples after stripping are shown In the attached Table. Reduction of the residual VCM, particularly with regard to QSQH-7, Is considered to be a slight Improvement over the current UCC production. However, the extreme stripping conditions (> 100*C) also resulted In severe resin degrada tion as shown by the high yellow factors. Stripped samples of VSJE-10 supplied to Goodrich have not been received. Please let me know If additional Information /kw Attachment UCC 049086 RESULTS OF 8. F. GOODRICH PILOT PLANT PROGRAM CONTINUOUS STRIPPING OF UCC SUSPENSION VINYL RESINS TO REMOVE VINYL CHLORIDE MONOMER Resin Type QSAN-7 QSQH-7 Sample Designation 11041104 A a 1104 C 1120 A 1120 B 1120 C Test Conditions (Minutes/"?J Residual VCM. r>nm Yellow Factor ffpC T>fl AInitial After Stripping ft 11,690 C 6.4/236 //3 6 1.0 7.8 7.4/236 1# 6.9/216 /cx ft'3 bC 21 *$.o 9.1 20,283 5.8/236 6.9/235 6.9/214 //* ft V732 11 <? n61 1.0 7.0 9.9 7.2 RHA:kw 12/11/75 '/JL. ztrtf*, \/C_ yv\ uJLj6r &***- 049087 I \r ucc 049088 Project 7716-75 December 28, 1975 Stripping Tests on Union Carbide1 FVC Reln Slurrlee in the 6-Inch Development Column by G. R. Huddleston end E. J. O'Connor SUMMARY Union Carbide, e potential licensee of B. F. Goodrich stripping technology, requested tests with three of their resin slurries to estab lish capability of the method and to provide stripped resin for their evaluation. One resin was a vinyl chloride homopolymer, one an ethylene-modified PVC and the third a vinyl acetate-vinyl chloride c - ; polymer. * Both the* homopolymer and the ethylene-modified resin were stripped in the 6-inch countercurrent steam stripping column at Brecksville under various operating conditions. Five-gallon samples from ach run were sent to Union Carbide for their evaluation. The two resins were handled satisfactorily in the column at atmospheric pressure and at 8 psig. The'homopolymer was reduced from 5,294 ppm in the cold feed to less than 3 ppm at 8 psig and to 11 ppm at 1.5 psig. The ethylenemodified resin was reduced from 4,475 ppm in the cold feed to about 10 ppm at 8 psig and to 54 ppm at 1.25 psig. Two attempts were made to strip the vinyl acetate copolymer under vacuum at 170*J*^ When the slurry entered the column it formed a stable froth that didLaot flow through the downcomers but instead went overhead. One attempt-was matte with addition of a defoamer which helped the flow of situate* the^particular defoamer uaed appeared to bo antagonistic to the ditpiisax*.system and caused separation of tbo resin into agglemer^ atas which stuck tw column surfaces, leaving only dear serum to travel " through tho downcomers. The vinyl acetate resin and serum were severely discolored even at the low temporature of the feed tank (100110*F) and the color increased in the column at 170*F. ucc 049089 Project 7716-75 2- December 28, 1975 OBJECTIVE To demonstrate capability of countercurrent column steam strip ping of vinyl chloride from Union Carbide's PVC resin slurries in the 6-inch development column to assist in sale of Goodrich stripping tech nology. CONCLUSIONS Union Carbide's homopolymer and ethylene-modified PVC resin slurries can be readily stripped in a countercurrent steam stripping . column at atmospheric pressure or higher. In a column with tray strip ping rates equivalent to that of the development column, vinyl chloride could be reduced from 10, 000 to l ppm in the homopolymer in about ( 11 trays at 8 psig and 16 trays at 1.5 psig. The ethylene-modified PVC is a little more difficult to strip and would require 16 and 21 trays respectively to reduce vinyl chloride from 10, 000 to 1 ppm. Union Carbide's vinyl acetate copolymer slurry forma a very stable froth under the vacuum vor.uiticns necessary to protect the resin from agglomeration. The stable froth did not flow through the column, A defoamer that is compatible with the dispersant system should allow c 1umn stripping. :\r * . INTRODUCTION In 1974, B. F. Goodrich Chemical developed stripping technology for removal of vinyl chloride from PVC resin slurries by countercurr nt steam in perforated tray columns. This development work was d ne in the 6-inch, 8-tray column at Brecksville and in the 30-inch, 17-tray column at Avon l.ake Geon East. Results from the development w re used for design of 54-inch, 20-tray columns which are now being installed at 5 BFG plants in the i;SA. Goodrich has offered the stripping technology for sale to the industry and several potential purchasers have visited Geon East to observe the 30-inch column in operation. U^C 049090 .F.OOOOtICH Project 7716-75 -3- December 28, 1975 Most of them have expressed an interest in having samples of their prod uct stripped in the 6-inch column to demonstrate stripping capability and to provide stripped samples of their products for evaluation. Union Carbide sent three 55-gallon drum samples, one each of a homopolymer, an ethylene-modified resin and a vinyl acetate copolymer. This report describes the tests and presents results. RESULTS AND DISCUSSION I. Equipment The 6-inch column is made up of stainless steel, in line "bull'a eye" sight glass sections obtained from the Ernst Gage Company. Per forated plate trays are installed between sections. The trays are stain less steel and are fitted with a 1-inch stainless steel tube to serve as a downcomer and a-wier to hold 1-1/2" depth on the tray. This represents a holdup volume about . 1734 gallons per tray and 1.3872 gallons total. Each tray has 17 holes 1/4" diameter on a 1-1/4" equilateral triangular spacing. Open area in the tray is about 3%. About 50 pounds per h ur of steam is required to support the slurry on the trays without allowing excessive weeping. With the limited downcomer capacity, this results in a higher steam to resin requirement than needed for adequate stripping. In production equipment, 0. 5 pound steam per pound of resin or less has been adequate. Steam is added below the bottom tray at a rata controlled by manual setting of the valve and pressure control. Effluent from the bottom tray collects in a sump and is discharged on level control. Steam from the column is condensed and pressure in the column is controlled by manual setting of the discharge valve ahead of the condenser. Feed slurry is heated in an agitated, closed slurry tank which is fitted with a circulating loop. Pressure in this tank is maintained several pounds higher than the column pressure. Feed to the column is pr vid d by a flush mounted valve in the circulating loop. The valve is activated by a pulse timer to control feed rate. For smoothest operation, the feed slurry is heated to near the same temperature as the column operating point. Feed significantly lower in temperature causes some steam c ndensation and a temporary upset with each pulse- As feed enters the c lumn, there is a flash above the lop tray so this tray does not receive the full ucc 049091 B. P. GOODRICH Bwsrrii Center Project 7716-75 -4- December 28. 1975 vinyl chloride load as measured in the cold slurry. A more realistic value is the vinyl chloride level measured in a hot feed sample that is flashed to the atmosphere. This technique was used and both hot and cold feed values are reported. Samples were also taken from trays 3, 6 and 8 and from the c lunu. discharge. Sample taps are flush with the tray surface. After some evidence of resin discoloration from heat aging in the feed tank at column temperature, the procedure has been modified to reduce temperature in the feed tank to about 150aF. This procedure was used for all Union Carbide resins. To compensate for the condensation of steam by the cooler feed, somewhat higher steam rates were used. Steam rate for calculating steam/resin ratios was considered as that amount which the condenser received. 11. Analytical e A. Vinyl Chloride Measurement Vinyl chloride content of the samples was determined at Avon Lake Plant Services Laboratory by Dot Lewis and John Whitney. Samples were sent to this lab in tightly sealed, 4-ounce glass bottles with electrical tape wrapped around the cap. Bottle contents were quickly reslurried and filtered in a Buchner funnel to remove most of the water. Samples of the wet cake were checked for total solids content and for vinyl chloride con tent by the head space method gas chromatography unit. Values were reported as ppm vinyl chloride in dry PVC resin by weight. B. Resin Properties Samples of each slurry were analyzed at Avon Lake Technical Center to determine average particle size, particle size distribution, inherent viscosity, porosity, average pore size and pore size distribution. These data are summarized in Table IV. UL Column Operation The sample drum contents are re slurried and transferred into the feed tank. Heat is then applied to the jacket to control slurry temperature near 150F. Just before the run is started, circulation of slurry in the feud loop is started. Pressure in the feed tank is maintained several pounds higher than column pressure, UCC 049092 .P.QOOOKICH Project 7716-75 -5- December 28, 1975 For each run the column is calibrated to establish condensate rate from heat loss to the atmosphere and steam rate for the two operating conditions chosen. About two hours are required for the column to reach steady conditions of condensate and steam flow. Steam pressure to th column is controlled at 70 psig by regulator. When the column conditions are steady, condensate from the bottom of the column is weighed to establish a rate and steam condensate from the condenser is weighed to establish a rate. Feed is then started to the colu:nn by turning on the pulse timer. For control of feed rate the timer opens the valve for 1 second, then keeps it closed for 29, 44 or 59 seconds depending on the feed rate desired. Feed flashes as it enters the column and froths for a few seconds on the top tray and to a lesser extent on the second tray, levels on the top two trays are high following the pulse, then the feed slowly works its way down the column. The effect of the pulse is dampened out by the two top trays and flow through the remainder of the column is quite smooth. Discharge from the column is steady with no evidence of the pulse. After allowing time for about two passes through the column* c Unc tion of a 5-gallon sample of stripped slurry is started. This coUeetion is made into an open pail directly from the column discharge. During this sample collection, the column effluent rate is determined by weighing the output for a specific time. Condensed steam is also weighed to determine a rate. By comparing these rates with the calibrated rates, a slurry feed rate is determined and the amount of steam condensed by the feed is also determined. After calibrations are established, samples are taken from the feed tank, trays 3, 6 and 8 and from the column discharge. Samples are taken into an open sample bottle, bottles are capped, then the cap is wrapped with electrical tape and sent to the laboratory for analysis. When the 5-gaUon sample collection is complete, the feed rat and/ or column pressure are changed for the next run. After steady state is established, the above sampling procedures are repeated. A theoretical residence time is calculated for each run. This cal culation is made on a tray-to-tray basis considering that the tray rec Ives all the slurry plus the steam condensed by the feed and that the condensate from heal loss to the atmosphere occurs equally on each tray. Volumes to the tray are corm-lud lor'composition and density. These resid nee times are theoretical and real values are somewhat less because the slurry is expanded by the passage of steam. In some calibration tests it has been estimated that the actual holdup volume is about 0.7 times ................... * ' t. P. GOODRICH tmirtfc Center 049093 APfifftP/X J> Project 7716-75 -6- December 28, 1975 theoretical at the steam rates used. This factor will no doubt vary with type of dispersant, total solids and other conditions. The theoretical residence times should be adequate for relative comparisons. Accurate measurement of differential pressure between top and bottom of the col umn could be used to calculate a more accurate column holdup, but this has not been applied to the 6-inch column. It was used for estimat s in the 50-inch column. IV. Operating Data and Analytical Results A. Homopolymer Resin QSAN Contents of the drum were reslurried and loaded to the feed tank a November 4, 1975. Solids content of the slurry was 33.7%. Runs were made at 8 psig, 236F using two feed rates and at 1.5 psig, 216F. At 236F vinyl chloride content was reduced from 5, 294 ppm in the c Id feed to less than 2 ppm. At 216F vinyl chloride content was reduced to 11 ppm and it is projected that another three trays would have reduced the level to 2 ppm. Data from these runs are shown in Table 1. Figure 1 shows a log plot of vinyl chloride content against tray number. Figure 1A shows a similar plot against residence time in minutes. In both plots the effluent values were considered as having occurred after one addi tional tray. B. Ethylene-modified Resin QSQH A first attempt was made to strip this sample on November 6, 1975. Shortly after feed was opened to the column, the feed pump motor threw the breaker and the circulating loop plugged. The slurry was cooled and returned to the drum. The column and lines were cleaned and other stripping tests were carried out. - Another attempt was made on November 20, 1975 but again the pump failed to handle the slurry and the lines plugged before feed was established to the column. The slurry was cooled and left in the feed tank while the lines were cleaned. A third attempt was made November 21, 1975 and it was successful. Before opening the feed tank to the pump, the circulating loop was filled with water to establish a good flow, then when feed was opened to the pump, it was able :< handle the slurry. Slurry .*s loaded to the feed tank had a solids content of 2 J. 8%. Runs were made at 8 psig, 23oJF using two feed rates and at 1.25 psig, 2l4*F. At 236F, vinyl chloride was reduced from 4,475 ppm M.GOODWCH ucc 049094 iusnrrh Center Project 7716-75 -7- December 28, 1975 in the cold feed to 10-25 ppm. At 214F, vinyl chloride content wee reduced to 54 ppm, end it is projected that five more trays would haw been needed to reach 10 ppm. Data from these runs are shown in Table II, Figure 2 and Figure 2A. C. Vinyl Acetate Copolymer VSJE This slurry was loaded to feed tank on November 13, 1975. As loaded, the slurry and serum were colorless but after heating to about 105aF, the serum was yellow to orange and after feeding to the column at 170F, the color of the resin and serum became deep orange col red. A run was attempted at a 17-inch Hf vacuum. When the slurry entered the column it formed a stable froth which did not flow down the column properly. The froth stayed on the trays and there was some agglomeration which plugged downcomers. Feed was discontinued and the column was cleaned. Another attempt was made on November 14, 1975, a* the same results were observed. The heavy froth built up on the top tray car ried over to the condenser as feed was continued. A defowner was added to the feed tank and appeared to help break the froth to some extent. More was added and flow started through the column, but the resin agglomerated and separated from the serum, leaving clear serum flowing through the column and resin clinging to the column surfaces. It appeared that the defoamer was antagonistic to the dispersant system. Another possible explanation was that the cloud point of the dispersant had been exceeded but contact with Union Carbide revealed that the cloud point was well above 212eF. Union Carbide suggested one of their specific defoamers but none was available in the area. About 15 gallons of the vinyl acetate slurry is retained at Bracks?--- ville. This is enough to make a run with Union Carbide's defoamer add d if further tests are desired. V. Discussion of Results From Figures 1 and 2, equations of the type C C0e"^^were derived, C represents the predicted vinyl chloride content in ppm at tray N when starting with a feed containing CQ ppm. The slope of the line is -A, and this value can be considered a rate of stripping factor. Similarly, from Figures lA and 2A, equations of the type C CQe" Bt were ucc 049095 B.F. GOOORICM Project 7716-75 -8- December 28, 1975 derived. In these equations -B is the slope of the line and t is the r sidence time in minutes. A and B are related by equations of the type: B_______Aifil-------- . t (for 8 trays) By using these equations, the number of trays or time required to strip slurry from one level of vinyl chloride to any other level can be estimated. In using the .e equations, Co should be taken as the vinyl chloride content actually received by the top tray. In the absence of an actual sample measurement from this tray, it is necessary to make an estimate. When feed enters the column, there is a significant flash of vinyl chloride as the slurry falls to the top tray. The degree of this flash is dependent on the temperature of the feed and the vinyl chloride content. For all these tests the CQ or hot feed value was determined by allowing a sample of the heated feed slurry to flash to the atmosphere* In most cases these values fit the plot quite well. Another way to eeti* mate the C0 is by backward extrapolation of the lower tray results. From the figures it can be noted that there is appreciable scatter of the data. There was some loss of vinyl chloride from small leaks in the system. To minimize the affect of this on the data, a hot feed sample was taken at the same time that other samples were taken from the e 1uxnn. When two feed rates are used under the same operating conditions, data from the two runs in most cases yield a line with essentially the same slope when plotted against tray number. When plotted against time, the fast feed rate data usually has a steeper slope indicating faster stripping at faster feed rates. These factors indicate that the number f trays is the controlling factor and not the residence time. Similar data were obtained during development work with the 30-inch, 17-tray c lumn. Obviously some minimum residence time is required for diffusion of the vinyl chloride from the particles and this time is quite short at tempfratures over 200F. Once the minimum time is exceeded, allowing more time has little effect on increased vinyl chloride removal. Analytical data from samples taken on tray 3 tend to fall belo*4 the line. This can probably be explained by considering the operating char acteristics of the development column. Feed is added by a pulse value which is open for 1 second, then closed for 29, 44 or 59 seconds depend ing on the feed rale desired. . The size of the slug of feed depends on . pressure differential acres* the valve from feed pump to the column. The slug of feed enters lIn: mlumn, fleshes and falls to the top tray where it ^ is licAlcd to column temperature. This Iray is llmnlcd at this time and the level gradually decreases until the next slug enters. Tray 2 is all ucc 049096 8. P. GOODRICH Rawerrh Canter Project 7716-75 -9- December 28, 1975 flooded as the top tray dumps but from this point down the column the levels are steady. The pulse effect is dampened out by the first two trays and flow discharge further down the column is steady with no indi cation of a pulse in the effluent discharge from the bottom tray. Because of higher levels and longer time on the two top trays plus heat up of the feed the results as analyzed on tray 3 samples are lower than would be achieved if feed were steady. Ideally, a steady feed should be provided for the development col umn, but it is quite difficult to handle low volumes of fast settling slurry. The pulse feed was chosen as a compro'nise and since data from the small column correlate very well with those from the 30-inch column, the pulse feed method is considered adequate for development tests* Rate factors obtained from the figures are listed in Table IV. From these rate factors, the number of trays needed to accomplish reduction of vinyl chloride from C0 to C can be estimated bys -In C/Co C G. R. Huddleston Pl ucc B. F. GOODRICH 8606KI 0 Column Operating Data Resin Id ntific'tion Number Run Nur/.ber Column Pressure, psig Bottom ,'empe return, *F Seconds oe tween Rilses Feed, 1/hr. Slurry, % Solids Resin, (/hr. Steam, s/hr. Steam/Re sin Ratio Feed Temperature, F RVCM, ppm. Cold Feed RVCM, ppm Hot Feed* RVCM, tray 3 tray 6 tray B effluent Residence Time, minutes tray 3 tray 6 tray 8 effluent** Condensate Calibration, |/hr. Steam Condensed by Feed, f/hr. Table I Homopolymer QSAN U04A 1104B 1104C 88 1.5 236 236 216 45 60 60 108,1 91.9 105.5 -33. 7--- 36.43 30.97 35.55 51.9 S3. 1 57.8 1.42 .1.71 1.63 151 153 154 3119 69 14 3 2.6 -5294--- 3593 2250 174 445 9 67 1.4 11 1.5 11 2.26 4.39 5.74 6.41 17.7 7.4 2.64 5.10 6.66 7.43 17.7 6.2 2.40 4.68 6.14 6.86 14.9 4.7 Table 11 Ethylene-modified PVC QSQH 1120A 1120B 1120C 8.5 8.25 1.25 236 235 214 45 60 60 99.5 78.7 87.0 ------- 23.8--- -- -- -- - 23.68 18.73 20.71 50.3 51.3 57.3 2. 12 2. 74 2.77 136 144 145 2911 452 64 31 27 - 4475----- 2483 2187 381 402 53 132 14 64 9 54 2.02 3.94 5.16 5.77 17.9 7.2 2.43 4.70 6.14 6.86 17.9 6.2 2.39 4. 67 6.12 6.84 14.8 4.6 m at The hot feed sample fleshed to the ktmotphera, 1 Residence time tor effluent 1* considered u one more trey then trey 8. rl Table III Vinyl Acetate Copolymer VSJE 1113 17-inch Hg vacuum 170 run unsuccessful P ro je ct 7716-75 Decem b r 28, 1975 o TABLE XV Summary of Union Carbide's Resin Properties and Stripping Rates Resin Identification Number Inherent Viscosity Porosity Average Particle Size, ft Particle Size Distribution, % Average Pore Size, fi Pore Size Distribution, % Run Number Stripping Temperature, *F Feed Rate, #/hour Rate Factor, A Rate Factor, B Homopol ynie r QSAN 0. 95 7 0. 259 184 30.52 0.71 5. 18 1104A 236 108. 1 .869 1.193 110413 236 91.9 .973 1. 155 1104C 216 105.5 .595 .780 Ethylene-modified PVC QSQH 7. 2 % ethylene 0.715 0. 161 200 42.53 0.82 9.38 U20A 236 99.5 .562 . 868 1120B 235 78.7 .626 .820 1120C 214 87. 0 .435 .554 O r" oO CCOO Vinyl Acetate Copolymer VSJE 17.2% vinyl acetate0.466 0. 030 131 44. 08 0. 706 87.53 1113 170F run unsuccessful * s o v<!t nn `ro .^U 3 V (I -a |0v0 sV* U-fv>l I sU>O11 S.P.GOOORICH lUoaidi Cmimt ucc 043100 F~ I auri. - B.P.GOOORICH iMMRtl Cwitlf . ucc 04 o102 I ucc 049104 INTERNAL CORRESPONDENCE OC 149- / CHEMICALS AND PLASTICS to (namc) Mr. R. L. Frantz COM^AMV location Texas City Plant oat* o. bo* t, tbxa* city, timi ?t**o January 13, 1976 coav to Dr. R. J. Anderson, 312 su*jc Mr. M. E. Eiscnhour Mr. J. B. Holdingsworth, MY (28) Dr. D. R. Montgomery Mr. F. S. Provenzano Mr. G. F. Tacquard/S. A. Dickerson Residual VCM Af tery>&tripping JAN 17 1577 R N WHEELER JR. For the past month samples of the slurry leaving the unit after c stripping have been taken and analyzed for residual VCM and color in order to develop reliable information to determine exactly where we stand on meeting the upcoming EPA regulations limiting VCM con centrations to an average of 400 ppm leaving the stripping vessels. This letter is to update you on the information that has been collected to date. With the Suspension slurries, duplicate samples of individual batches were taken, the batch number, termination pressure drop, BDT and stripping conditions were recorded. Likewise, single samples of the Mon-Solvent slurry leaving the flash tank were taken and conditions recorded. The complete results are listed in the following tables and summarized below: ucc 049105 Hosidual VCM Af"er Stripping Page 2 Resin Trpe.... QSAP VSJE QSAL QSQF QSAN QSAN VSKK QSAH QYNL Prescribed Stripping Conditions Temp Time Vacuum 8S#C 85"C 85C 85C 85C 80C 80C 85C 8385 30 min 30 min 30 min 30 min 30 min 30 min 30 min 30 min 15" 15" 15" 15" 15" 15" 15" 15" 11" 14" Color 3.4 6.3 .3.4 5.1 4.0 4.2 7.9 5.6 3.7 Residual VCM 78 1115 144 840 836 537 1455 1256 248 In looking at the complete data in the tables, the results in some cases are quite variable with several obvious inconsistencies. (Those results identified with an asterisk (*) were not included in the averages.) More information will be gathered to help re solve the discrepancies. RK/st Attachments Rick Keefe t ucc 049106 TABLE I QSAP Date 12/6/76 Batch No. 6-10-187 aP - BDT - Conditions Temp Time ~ 85 30 min VAc 15" Color 3.4 3.3 VCM 81 76 Suspending Agents: F-50; K-J Additives: Bis-A at 10# aP ucc 049107 TABLE II VSJE Date 12/6/76 12/6/76 Batch No. 11-15-357 8-3-358 aP - BDT - *3 Conditions Temp Time 85* 30 min 15" 85 25 15" Color 6.0 5.9 6.6 6.6 VCM 1091 1033 1256 1078 Suspending Agent Additives HEMC Bis-A? EPO; Irg. 1076 ucc 049108 TABLE III QSAL Date 12/6/76 Batch No. 22-3-95 12/20/76 6-11-16 12/21/76 2-12-22 Conditions A P BDT Temp Time VAc Color - - 85 30 min 15" 2.8 2.8 -- -- 83 40 18" 3.8 3.8 - 1 8S 20 15" 3.0 3.0 VCM 932* 938* 169 166 119 121 Suspending Agents: F-50; K-J Additives: EDTA ucc 049109 TABLE IV QSQF Date Conditions Batch No. -A-* BDT Temp Time VAc Color VCM 12/8/76 20-12-10 12/9/76 20-1-20 12/11/76 23.-5-43 12/10/76 24-1-32 12/12/76 22-11-61 12/13/76 17-4-65 12/14/76 25-11-75 12/15/76 26-9-80 12/16/76 25-1-86 12/16/76 18-8-87 12/17/76 24-6-97 12/17/76 18-9-98 15# 0# 40# 0# 0# 0# 0# 5# 0# 25# 10# 10# 85* 30 min 15" -- 496 468 - 85 - - 85 - 45 30 15 m 1465 1497 18 5.2 1056 5.2 1073 - 85 - - 86 - 30 40 12 4.9 4039* 4.9 3572* 19 5.3 204 355 - 86 -- 45 16 4.7 540 589 - 85 - 30 16 5.0 339 382 - 85 25 16 4.3 860 660 - 85 40 18 5.6 1929 1696 - 83 -- 40 18 5.5 1003 942 - 82 30 12 5.1 1549* 1539* - 80 30 13 5.3 626 635 Suspending Agents: F-50; K-J Additives: Irg. 1076; Bis-A 9 20# 4 P OCC 0<(9li0 TABLE V QSAN Date 12/8/76 Batch No 2-9-6 12/10/76 4-9-27 12/11/76 5-9-30 12/13/76 1-6-46 12/14/76 2-3-53 12/15/76 6-7-57 -12/16/76 4-1-66 12/17/76 2-7-74 12/17/76 3-6-76 12/20/76 17-2-5 12/20/76 18-1-6 12/12/76 1-5-36 AP 12# 45# 10# 6# 0# 5# 10# 25# 15# 12# 20# 0 BDT #1 #1 #1 #1 #1 #1 #1 #1 #1 #1 Conditions Temp Time VAC 80" 30 min 15" 80 40 15 80 30 16 80 30 16 80 30 18 80 25 13 85 45 18 80 20 18 85 30 15 85 30 14 85 20 14 80 30 15 Color 3.8 4.4 5.2 3.9 3.9 3.9 3.8 3.9 4.4 4.2 VCM 737 252 445 408 282 280 816 953 194 198 850 252 226 213 327 550 153 149 1488 1243 1642 1574 1000 1051 Suspending Agents: Additives: F-50; K-J EDTA; Irg. 1076 ucc 049111 TABLE VI VSKK Date 12/21/76 12/28/76 12/28/76 1/4/77 . 1/4/77 1/4/77 ("1/5/77 Batch No. 9-3-22 12-7-51 15-7-53 9-3-131 10-2-132 7-13-133 7-15-149 A 66* 63* 25* 90* 85* 70* 75* BDT *2 *3 *2 *2 *3 *2 *3 Conditions Temp Time VAc 80* 40 min 15" 55 120 15 80 40 15 80 60 15 80 20 15 80 15 15 80 30 15 Color 9.4 6.1 6.4 VCM 2824 1134 7239* 7359* 1520 1076 962 988 3391 1665 1275 1333 1175 1405 Suspending Agents: HEMC; F-50 Additives: Bis-A; EPO ucc 049112 I TABLE VII QSAH Date 1/4/77 1/4/77 1/5/77 Batch No. 20-5-42 AP 90# 17-8-45 120# 22-6-46 30# Conditions BDT Temp Time VAC Color VCM #: 85 30 min 16" - 385 416 #5 85 30 15 - 696 653 #; 85 30 15 5.6 2741 2624 Suspending Agents: F-50; K-J Additives: EDTA; EPO IJCC t 049113 049115 internal correspondence UC I4t- CHEMICALS AND PLASTICS T , (NAME, Mr> R> May c^mnanv Buildino 114 (.-.CAT, N TEXAS CITY PLA.TT O. SOX 4l. TEXAS CITV, TEXAS ItMt OATS July 7t 1976 r r, i*r.unpy p *1r. A. A. Peterson Mr. n. T. Pyle Mr. *5. F, Tacauard y'lr. R. n. !'heeler - 514 r . HU JUL U 1976 R N WHEELEK J.<. Dear Ross: At your reouest, spot samples of VYMH were obtained from the slurry tank, dryer feed (off the Bird) and dryer to determine residual vinyl chloride. These data are shown in the attached table, indicate that a reduction of residual VCM from approximately Z000 ppm to < 50 ppm occurs during various drying stages at Building 120, Please let me know if additional Information is desired. VenLtruly yours /kw Attachment , Arnold ^Cc <*ni is i f G ucc 049117 Bffi TECHNICAL s* - DISTRIBUTION ; 'vt Brecksvilltf R. K. Schlatzer RbD Files (2) Cleveland Office H. R. Calsing X^A. L. Hastings i2) J. M. Hyslop {Z ) E. C. Schwaegcrle G. S. Fusek J. E. Klein Avon Lake G. N. Grellinger ALTC F. E. Krause E.A. Collins - L. A. Chandler G. D. Longeway Project 7716-75 December 28, 1975 TECHNICAL SERVICE REPORT STRIPPING TESTS ON UNION CARBIDE'S PVC RESIN SLURRIES IN THE 6-INCH DEVELOPMENT COLUMN by G. R. Huddleston and E. J, O'Connor IJCC 049113 6. F. GOODRICH Research Center project 7716-75 December 28, 1975 Stripping Tests on Union Carbide's FVC Regin Slurries in tlit; 6-inch Development Column by C. R. Huddleston and E. J, O'Connor SUMMARY Union Carbide, a potential licensee of B. F. Goodrich stripping technology, requested tests with three of their resin slurries to estab lish capability of the method and to provide stripped resin for their evaluation. One resin was a vinyl chloride homopolymer, one an ethylene-modified PVC and the third a vinyl acetate-vinyl chloride co polymer. Both the homopolymer and the ethylene-modified resin were stripped in the 6-inch countercurrent steam stripping column at Brecksville under various operating conditions. Five-gallon samples from each run were sent to Union Carbide for their evaluation. The two resins were handled satisfactorily in the column at atmospheric pressure and at 8 psig. The hbmopolymer was reduced from 5,294 ppm in the cold feed to less than 3 ppm at 8 psig and to 11 ppm at 1. 5 psig. The ethylenemodified resin was reduced from 4,475 ppm in the cold feed to about 10 ppm at 8 psig and to 54 ppm at 1.25 psig. Two attempts were made to strip the vinyl acetate copolymer under vacuum at 170F. When the slurry entered the column it formed a stabl froth that did not flow through the downcomers but instead went overhead. One attempt was made with addition of a defoamer which helped the flow of slurry, but the particular defoamer used appeared to be antagonistic to the dispersant system and caused separation of the resin into agglomer ates which stuck to column surfaces, leaving only clear serum to travel through the downcomers. The vinyl acetate resin and serum were severely discolored even at the low temperature of the feed tank (100110aF) and the color increased in the column at 170F. ucc 049119 B. t. GOODRICH HeMarch Center Project 7716*75 2- - December 28, 1975 OBJECTIVE To demonstrate capability of countercurrent column steam strip ping of vinyl chloride from Union Carbide's PVC resin slurries in the 6-inch development column to assist in sale of Goodrich stripping tech nology. CONCLUSIONS Union Carbide's homopolymer and ethylene-modified PVC resin slurries can be readily stripped in a countercurrent steam strippingcolumii at atmospheric pressure or higher. In a column with tray strip ping rates equivalent to that of the development column, vinyl chloride could be reduced from 10, 000 to 1 ppm in the homopolymer in about 11 trays at 8 psig and 16 trays at 1. 5 psig. The ethylene-modified PVC is a little more difficult to strip and would require 16 and 21 trays respectively to reduce vinyl chloride from 10,000 to 1 ppm. Union Carbide's vinyl acetate copolymer slurry forms a very stable :.-`.th under the vacuum ci*.ions necessary to protect the resin from agglomeration. The stable froth did not flow through the column. A defoamer that is compatible with the dispersant system should allow col umn stripping. INTRODUCTION In 1974, B. F. Goodrich Chemical developed stripping technology for removal of vinyl chloride from PVC resin slurries by countercurrent steam in perforated tray columns. This development work was done in the 6-inch, 6-tray column at Brecksville and in the 30-inch, 17-tray column at a-on Lake Go on East. Results from the development were used for design ci 54-ir.ch, 20-tray columns which are now being installed at 5 BFG plar/.s in the U.6A. Goodrich has offered the stripping technology for sale :o the industry and several potential purchasers have visited Geon East to observe the 30-mch column in operation. IIGG 049120 6. F. GOODRICH Research Center Project 7716*75 -3- December 28, 1975 Most of then', have expressed an interest in having samples of their prod uct stripped in the 6-inch column to demonstrate stripping capability and to provide stripped samples of their products for evaluation. Union Carbide sent three 55-gallon drum samples, one each of a nomopolymer, an ethylene-modified resin and a vinyl acetate copolymer. This report describes the tests and presents results. RESULTS AND DISCUSSION I. Equipment The o-inch column is made up of stainless steel, in line "bull's eye" sight glass sections obtained from the Ernst Cage Company, Per forated plate trays are installed between sections. The trays are stain less steel and are fitted with a 1-inch stainless steel tube to serve as a downcomer and a wier to hold 1-1/2" depth on the tray. This repres nts a holdup volume about . 1734 gallons per tray and 1. 3872 gallons total. Each tray has 17 holes 1/4" diameter on a 1-1/4" equilateral triangular spacing. Open area in the tray is about 3%. About 50 pounds per hour of steam is required to support the slurry on the trays without allowing excessive weeping. With the limited downcomer capacity, this results in a higher steam to resin requirement than needed for adequate stripping. In production equipment, 0. 5 pound steam per pound of resin or less has been adequate. Steam is added below the bottom tray at a rate controlled by manual setting of the valve and pressure control. Effluent from the bottom tray collects in a sump and is discharged on level control. Steam from the column is condensed and pressure in the column is controlled by manual setting of the discharge valve ahead of the condenser. Feed slurry is heated in an agitated, closed slurry tank which is fitted with a circulating loop. Pressure in this tank is maintained several pounds higher than the column pressure. Feed to the column is pr vided by a flush mounted valve in the circulating loop. The valve is activated by a pulse timer to control feed rate. For smoothest operation, the feed slurry is heated to near the same temperature as the column operating poir.:. Feed .-.ignificantly lower in temperature causes some steam conden sation and a temporary upset with each pulse.. As feed enters the column, there is a flash above the top tray so this tray does not receive the full B. F. GOODRIC Research Cent UCC 0491:i Project 7716-75 -4- December 28, 1975 vinyl chloride loud as measured in the cold slurry, A more realistic value is the vinyl eldondo level measured in a hot feed sample that is flashed to the atmosphere. This technique was used and both hot and cold feed values are reported. Samples vvre also taken from trays- 3, 6 and 8 and from the column discharge. Sample taps are flush with the tray surface. .After some evidence of resin discoloration from heat aging in the feed tank at coh mn temperature, the procedure has been modified to reduce tempera;ure in the feed tank to about 150F. This procedure was used for all Un on Carbide resins. To compensate for the condensation of steam by the cooler feed, somewhat higher steam rates were used. Steam rate for calculating steam/resin ratios was considered as that amount which the condenser received. 11. Analytical A. Vinyl Chloride Measurement Vinyl chloride content of the samples was determined at Avon Lake Plant Services Laboratory by Dot Lewis and John Whitney. Samples were sent to this lab in tightly sealed, 4-ounce glass bottles with electrical tape wrapped around the cap. Bottle contents were quickly reslurried and filtered in a Buchner funnel to remove most of the water. Samples of the wet cake were checked for total solids content and for vinyl chloride con tent by the head space method gas chromatography unit. Values were reported as ppm vinyl chloride in dry PVC resin by weight. B. Resin Properties Samples of each slurry were analyzed at Avon Lake Technical Center to determine average particle size, particle size distribution, inherent viscosity, porosity, average pore size and pore size distribution. These data are summarized in Table IV, HI. Column Operation The sample drum contents are reslurried and transferred into the feed tank. Heat is then applied to the jacket to control slurry temperature near 150F. Just before the run is started, circulation of slurry in the feed loop is started. Pressure in the feed tank is maintained several pounds higher than column pressure. UCC 049122 B. f. GOODRICH Research Center Project 7716-75 o- December 23, 1975 For each run the column is calibrated to establish condensate rate from heat loss to the atmosphere and steam rate for the two operating conditions chosen. About two hours are required for the column to reach steady conditions of condensate and steam flow. Steam pressure to the column is controlled at 70 psig by regulator. When the column conditions are steady, condensate from th bottom of the column is weighed to establish a rate and steam condensate from the condenser is weighed to establish a rate. Feed is then started to th-.- column by turning on the pulse timer. For control of feed rate the timer opens the valve for 1 second, then keeps it closed for 29, -14 or 59 seco ids depending on the feed rate desired. Feed flashes as it enters the column and froths for a few seconds on the top tray and to a lesser extent on the second tray. Levels on the top two trays are high following the pulse, then the feed slowly works its way down the column. The effect of the pulse is dampened out by the two top trays and flow through the remainder of the column is quite smooth. Discharge from the column is steady with no evidence of the pulse. After allowing time for about two passes through the column, collec tion of a 5-gallon sample of stripped slurry is started. This collection is made into an open pail directly from the column discharge. During this sample collection, the column effluent rate is determined by weighing the output for a specific time. Condensed steam is also weighed to determine a rate. By comparing these rates with the calibrated rates, a slurry feed rate is determined and the amount of steam condensed by the feed is also determined. After calibrations are established, samples are taken from the feed tank, trays 3, 6 and 8 and from the column discharge. Samples are taken into an open sample bottle, bottles are capped, then the cap is wrapped with electrical tape and sent to the laboratory for analysis. When the 5-gallon sample collection is complete, the feed rate and/ or column pressure are changed for the next run. After steady state is established, the above sampling procedures are repeated. A theoretical residence time is calculated for each run. This cal culation is made on a tray-to-tray basis considering that the tray receives all the slurry plus the steam condensed by the feed and that the condensate from heat loss to the atmosphere occurs equally on each tray. Volumes to the tray are corrected for composition and density. These residence times are theoretical ar.o real values are somewhat less because the slurry is expanded bv the passage of steam. In some calibration tests it has been estimated that the actual holdup volume is about 0.7 times B. f. GOODRICH Ratearch Center ucc 049123 Projec: 771o-75 -6- December 23, 1975 theoretical at the steam rates used. This factor will no doubt vary with type of dispersant, total solids and other conditions. The theoretical residence times should be adequate for relative comparisons. Accurate measurement of differential pressure between top and bottom of the col* umn could be used to calculate a more accurate column holdup, but this has not been applied to the 6-inch column. It '*as used for estimates in the 30-inch column. IV. Operatm,; Data and Analytical Results A. Homopolymer Resin QaAN Contents of the drum were re slurried and loaded to the feed tank on November 4, 1975. Solids content of the slurry was 33.7%. Runs were made at 8 psig, 23bsF using two feed rates and at 1.5 psig, 216F. At 236F vinyl chloride content was reduced from 5, 294 ppm in the cold feed to less than 2 ppm. At 216F vinyl chloride content was reduced to 11 ppm and it is projected that another three trays would have reduced the level to 2 ppm. Data from these runs are shown in Table 1. Figure 1 shows a log plot of vinyl chloride content against tray number. Figure lA shows a similar plot against residence time in minutes. In both plots the effluent values were considered as having occurred after one addi tional tray. B. Fthvlene-medifled Resin QSQH A first attempt was made to strip this sample on November 6, 1975. Shortly after feed was opened to the column, the feed pump motor threw the breaker and the circulating loop plugged. The slurry was cooled and returned to the drum. The column and lines were cleaned and other stripping tests were carried out. Another attempt was made on November 20, 1975 but again the pump failed to handle the slurry and the lines plugged before feed was established to the column. The slurry was cooled and left in the feed tank while the lines were cleaned. A third attempt was made November 21, 1975 and it was successful. Before opening the feed tank to the pump, the circulating loop was filled with water to establish a good flow, then when feed was opened to the pump, it was able- to handle the slurry. Slurry * s loaded to the feed tank had a solids content of 2i. a1'-. Runs were rr.acc at 3 psig, 23osF using two feed rates and at 1. 25 psig, 2Ti 'l'. ,\t djuT, inyi chloride was reduced from 4,475 ppm B. f. GOODRICH Research Center yee 049124 Project 7716-75 -7- December 28, 1975 in the cold Iced to 10-25 ppm. At 214F, vinyl chloride content was reduced to 54 ppm, and it is projected that five more trays would have been needed to reach 10 ppm. Data from these runs are shown in Table II, Figure 2 ar.d Figuie 2A. C. Vinyl Acetate Copolymer VSJE This slurry was loaded to feed tank on November 13, 1975. As loaded, the slurry and serum were colorless but after heating to about 105F, the serum was yellow to orange and after feeding to ti e column at 170F, the color of the resin and serum became deep orarge colored. A run was attempted at a 17-inch Hg vacuum. When the slurry entered the column it formed a stable froth which did not flow down the column properly. The froth stayed on the trays and there was some agglomeration which plugged downcomers. Feed was discontinued and the column was cleaned. Another attempt was made on November 14, 1975, and the same results were observed. The heavy froth built up on the top tray and car ried over to the condenser as feed was continued. A defoamer was added to the feed tank and appeared to help break the froth to some extent. More was added and flow started through the column, but the resin agglomerated and separated from the serum, leaving clear serum flowing through the column and resin clinging to the column surfaces. It appeared that the defoamer was antagonistic to the dispersant system. Another possible explanation was that the cloud point of the dispersant had been exceeded but contact with Union Carbide revealed that the cloud point was well above 212F. Union Carbide suggested one of their specific defoamers but none was available in the area. About 15 gallons of the vinyl acetate slurry is retained at Breckaville. This is enough to make a run with Union Carbide's defoamer added if further tests are desired. V. Discussion of Results From Figures 1 and 2, equations of the type C = C0e"AISf were derived. C represents the predicted vinyl chloride content in ppm at tray N when starting with a feed containing C0 ppm. The slope of the line is - A, and this value can be considered a rate of stripping factor. Similarly, from Figures lA and 2A, equations of the type C s C0e*. Bt were B. F. GOODRICH Rcieorth Center ucc 049125 Project 7716-75 -3- December 28, 1975 derived. In these equations -B is the slope of the line and t is the resi dence time in minutes. A and B are related by equations of the type: b= A(8) t (for 8 trays) By using these equations, the number of trays or time required to strip slurry from one level of vinyl chloride to any other level can be estimated. In using these equations, C0 should be taken as the vinyl chloride content actually received by the top tray. In the absence of an actual sample measurement from this tray, it is necessary to make an estimate. When feed enters the column, there is a significant flash of vinyl chloride as the slurry falls to the top tray. The degree of this flash is dependent on the temperature of the feed and the vinyl chloride content. For all these tests the CQ or hot feed value was determined by allowing a sample of the heated feed slurry to flash to the atmosphere. In most cases these values fit the plot quite well. Another way to esti mate the C0 is by backward extrapolation of the Lower tray results. From the figures it can be noted that there is appreciable scatter of the data. There was some loss of vinyl chloride from small leaks in the system. To minimize the effect of this on the data, a hot feed sample was taken at the same time that other samples were taken from the col umn. When two teed rates are used under the same operating conditions, ccia from the :wo runs m most cases yield a line with essentially the same slope when plotted against tray number. When plotted against time, the fast feed rate data usually has a steeper slope indicating faster stripping at faster feed rates. These factors indicate that the number of trays is the controlling factor and not the residence time. Similar data were obtained during development work with the 30-inch, 17-tray column. Obviously some minimum residence time is required for diffusion of the vinyl chloride from the particles and this time is quite short at tempera tures over 200F. Once the minimum time is exceeded, allowing more time has little effect on increased vinyl chloride removal. Analytical data from samples taken on tray 3 tend to fall beloW. the line. This can probably be explained by considering the operating char acteristics of the development column. Feed is added by a pulse value which is open for 1 second, then closed for 29, 44 or 59 seconds depend ing on the feed rate desired. The size of the slug of feed depends on pressure differential across the valve from feed pump to the column. The siue of fvi'd . rs the column, flashes and falls to the top tray where it is heater: to column temperature. This tray is flooded at this time and the level gradually decreases until the next slug enters. Tray 2 is also B.F. GOODRICH Retaarch Cantar ucc 043126 project 771o-75 -la- December 28, 1975 flooded as the top tray dumps but from this point down the column the levels are steady. The pulse effect is dampened out by the first two trays and flow discharge further down the column is steady with no indi cation of a pulse in tne effluent discharge from-the bottom tray. Because of higher levels and longer time on the two top trays plus heat up of the feed the results as analyzed on tray 3 samples are lower than would be achieved if feed were steady. Ideally, a steady feed should be provided for the development col umn, but it is quite difficult to handle low volumes of fast settling slurry. The pulse feed was chosen as a compromise and since data from the small column correlate very well with those from the 30-inch column, the pulse feed method is considered adequate for development tests. Rate factors obtained from the figures are listed in Table IV. From these rate factors, the number of trays neeued to accomplish reduction of vinyl chloride from C0 to C can be estimated by: -In C/ Co G. R. Huddleston O'Connor B. F. GOODRICH Research Center ucc 049127 Column Operating Data Re sin Identification Number Run Number Column Pressure, psig Bottom Temj>erature, F Seconds between Pulsce Feed, |/hr. Slurry, % Solids Resin, I/hr. Steam, I/hr. Steam/Resin Ratio Feed Temperature, F RVCM, ppm. Cold Feed RVCM, ppni Hot Feed* RVCM, tray 3 tray 6 tray 8 effluent Residence Time, minutes tray 3 tray 6 tray 8 effluent** Condensate Calibration, I/hr. Steam Condensed by Feed, f/hr. Table 1 Homopolymc r QSAN 1104 A 1104 B 1104C 88 1.5 236 236 216 45 60 60 108. 1 91.9 105.5 -33.7------ 36.43 30.97 35.55 51.9 53. 1 57.8 1.42 1.71 1.63 151 153 154 3119 69 14 3 2.6 --5294------ 3593 2250 174 445 9 67 1.4 11 1.5 11 2.26 4.39 5.74 6.41 17.7 7.4 2.64 5.10 6. 66 7.43 17.7 6.2 2.40 4. 68 6. 14 6.86 14.9 4.7 Table II Ethylenei-modified PVC QSQH U20A U20B U20C 8.5 8.25 1.25 236 235 214 45 60 60 99.5 78.7 87. 0 -- 23.8-- -- 23.68 18.73 20. 71 50.3 51.3 57. 3 2. 12 2.74 2.77 136 144 145 29U 452 64 31 27 4475-2483 381 53 14 9 2187 402 132 64 54 2.02 3. 94 5. 16 5.77 17.9 7.2 2.43 4.70 6. 14 6.86 17.9 6.2 2.39 4.67 6. 12 6.84 14.8 4.6 O 9 Cl hot feed sample was flashed to the atmosphere, RSft eofsidence time (or effluent ia cone ide red a a one more tray than tray 8. nu Tabic III Vinyl Acetate Copolymer VSJE 1113 17-inch Hg vacuum 170 run unsuccessful P ro je c t 7716-75 D e ce m b e r 28, 1975 TABLE IV Summary of Union Carbide's Resin Properties and Stripping U ile Ream Identification Number Inherent Viscosity Purosily Average Particle Size, ft Particle Size Distribution, % Average Pore Size, ft Pore Size Distribution, % Run Number Stripping Temperature, F Feed Kate, K/hour Kate Factor, A Rate Factor, 0 I lomopol y me r QSAN 0. 957 0. 259 184 30. 52 0. 71 5. 18 1 104 A 236 108. 1 .869 1. 193 1104 B 236 91.9 . 973 l. 155 1104C 216 105.5 .595 . 780 Ethylene-modified PVC QSQH 7. 2 % ethylene 0.715 0. 161 200 42.53 0. 82 9. 38 1120 A 236 99.5 .562 .868 1120B 235 78.7 .626 . 820 1120C 214 87. 0 .435 . 554 Vinyl Acetate Copoly e i VSJE 17. 2*io vinyl acela! 0.4 66 0. 030 131 44. 08 0. 706 87. 53 1113 170F run unsuccessful V 4 W JCW W I I4 W - IJ D e ce m b e r 28, 1975 O croo Oo in 5* ucc 049130 045131 IJCC 049133 Ucc OlQl;--; PRIVELEGED DOCUMENT Bates number ^has been skipped /d L' ucc 049157 Visit To General Tire ; R ibber C'o. i'VC rechni-.lojv - S*yjiprr>btfr I,,"4 2. % Q. How are vinyl chloride vapors removed from autoclave before entr A. Autoclave is filled with 130*F water to displace vinyl chloride vapc to the gas holder. Q. What is the operating pressure of the gas t A. The gas holder operates at 22-inches Hz0 gas holder (Type o. ji /O a Q. How long does it take to fill autoclave with water to displace vinyl chloride vapors? Where does the water go? A. It takes 12 minutes to fill autoclave and 15 minutes to empty. Water is not re-used -- it goes to the waste treatment area. Q. What type of water is used to fill autoclaves? A. Raw, lake water is used. Q. What is stated capacity of plant? A. Annual production capacity of plant is 125 MM pounds. Q. After maintenance finish cleaning autoclave, how is it pressure tested? A. Again, autoclave is filled with water and hydrostatically tested. ucc 049158