Document k9ywv2ZrpnMm8nppq2D7VBO9n

cc: Those present and -'ti-r is-: - Aleaeander/Jaek/Jones H. K. Eckert H. G. Schleicher if. H. Lane F. A. Sherwood J. S. Putnam J. C. 'rfrobleskl MINUTES ON DISCUSSION WITH MR. R. E. LSNZ ON START-UP AND OPEHhTION OF THE SICE VCM PLANT IN ITaLY December 5, 1952 Present N. L Hardwicke B. H. Hurtaog W. R. Johnson R. E. Len? (St. Louis) C. T. Murray R. G. Powell G. T. Ryan W H. Stanton S. B. Wilson W. F. Yates 1. Elock Flow Diagram Attached (Figure 2) is a block ilow diagram oi the Italian plant. Mr Len/ was the representative of the General Engineering Dept, on the start-up oi this plant. The diii'erences between thia plant and ours derive largely iram troubles in procuring certain equipment for the Italian plant. 2. R.sw Materials Acetylene is generated by the calcium carbide px'oceas. The purity requirements are high and the acetylene is scrubbed with cold trichloroethane prior to use. The feed acetylene therefore contains a little TCE. HC1 is obtained from the combustion of Cla with Ha, Most of the down time has been caused by troubles in HC1 generation. $. Tars in Product As far us they have been able to determine, no heavy tars or acetaldehyde have been made in the reactor. Mr. Len<i pointed out that the hot spot is still several ieet from the reactor tube exit, so the worst heat conditions have not been reached. The bottom head of their reactor, the off-gas water scrubber, and the connecting piping are rubber-lined. This lining seems to be holding up very well, it is surprising that no acetaldehyde has been detected since they have had trouble keeping their HC1 dry. Mr. Lenz estimated the water content oi their acid run 100 ppm. He also stated that their control lab staff were new and lacked pro:iciency, so much analytical RSV0030884 2- - data had an element of doubt. There is enough water to give them corrosion troubles in the HC1 transfer lines* 4. HgCla Carried Out of Reaetor No mercuric chloride has been detected in the water blow down from the water scrubber. However, Mr. Lenz thinks there may be some when the hot spot has moved close to the bottom of the reactor. The Italian plant discharges the water scrubber blowdown water directly to the sewer. 5. Reactor Size and Catalyst The Italian reactor contains 660 two inch tubes which are 5-5 meters long. The catalyst is a Davidson commercial catalyst of mercuric chloride on Pittsburg carbon. This carbon has proven much too fragile. Future catalyst will be made in Italy on a hard German carbon. The normal operating rate is 19 lbs/day/tube which is equivalent to our 17.5 lbs/day/tube as their tubes are slightly larger. 6. Reactor Loading The greatest difficulty experienced in the start-up of the reactor was proper loading. After the tubes were filled with catalyst, the pressure drop across each tube was checked. (Attached, Figure 1, is the setup they used for checking pressure drop.) Five liters/min. of Na was blown through each tube. They had planned to reload those tubes which were more than 1C# above or below the mean pressure drop. However, the Italians were in a hurry to get into production and would agree to repacking only 18 of the worst tubes of low pressure drop. Another factor in their decision not to repack all the tubes which should have been repacked was their plans to replace the Davidson catalyst with a Boyd type on a hard carbon to be made In Italy at an early date. They found an excess of fines in their catalyst but could not get an agreement to screen them out. 7- Reaetor Start-up and Operation Mr. Lem had the following comments on reactor start-up and operation. a) The catalyst should always be conditioned by starting at 50# of design rate. Otherwise the hot spot temperature will run high (about 250 C). b) If too large an excess of either HCl or reaction will be obtained. is fed, no RSV0030885 \ -3- c) Tars are not made even If slightly wet gasses are fed, d) They had trouble with their HC1 and CzH* Instruments (Foxboro rotometers) on start-up, but controlled their feed stream with analysis of the gasses leaving the oottom of the reactor. They analyzed for both HC1 and acetylene. They ran about 7% excess HC1 due to high cost of acetylene . e) Their catalyst was exposed to damp weather for several days while loading the reactor. To dry it, the shell vas filled with 110 C water and dry Ha was blown through the catalyst for 24 hours. f) The reactor hot spot temperature was 150 C after 650 hours of operation. The Jacket temperature at and above ;he hot spot ran 100-110* C while below the hot spot 50 C was normal. g) The hot spot has moved about 2 ft. after 650 hours of operation. h) On one occasion a leak in a tube caused the screen support at the bottom of the tube to corrode out and the catalyst fell out. Their conversion dropped considerably because about one third of their gas short-circuited through this empty tube. i) When a section of their reactor was repacked because of the leaking tube described above, they found hard sections of catalyst at the tube hot spots. (Their reactor cata lyst support is divided into eight sections.) The position of this section in the several tubes indicated the hot spot to be at about the same location in each tube. These hard sections were easily broken out with a rod. 8. Comments cn Our System a) Hr. Lenz emphasized the importance of properly loading the reactor. b) Our conveyor system should save a lot of drum handling. Mr. Lenz doubted that we would shatter much catalyst by handling It with this system. c) Ke thought our vacuum unloading system would be of great utility to ub. The Italians build themselves a make shift vacuum system for catalyst unloading which handi capped their work because of low efficiency.(10 - 12 minutes to unload a tube). d) We could probably operate without 22D1, D2 and D3 during RSV0030886 s early part of catalyst life If we can tolerate the C02 of the acetylene feed. e) We Bhould screen a few drums of catalyst and if the fines are excessive we should screen all catalyst prior to use. f) Prior to loading, the reactor tubes should be cleaned with wire brushes. 9. Product purity The VCM produced by the Italian plant contains a little acetaldehyde. Acetaldehyde caused foaming In the VCM caustic wash step and increases caustic consumption. C2H2 cannot hurt polymerization, but it does create an explosion hazard. Monomer purity is critical but it isn't known what the critical impurities are. 10. Safe Practice for Catalyst Handling The Italian plant did not enforce safety rules and so are running a risk of accumulative mercury poisoning of some personnel. When handling catalyst (which will dust some no matter how carefully handled) respirators and rubber gloves should be worn. Also at the end of the day the worker should bathe before going home and the clothing should be picked up and cleaned prior to reuse. BHH/4e B. H. Hartzog RSV0030887 V ^Monsanto Chemical Company PROCESS ENGINEERING DEPT, .TEXAS CITY, TEXAS Job So No Rett Department l)eslnU in Pate t l\eck.el In I>tc P^ftp of Pafies ____Z-2. Syslew _ Ar ' .. ' l>e*crlptlnn iVreASur-snf ?!)/- 7~e*es < _\ . _ J ;~</rcf> tlhretSfA Item No -ggx*. z*________ :_________ ** r t3f sow i RSV0030888 f ` - .Monsanto Chemical Company 'XI*~\ Ttcoms TEX^S CITY, TEXAS > MM "1-------------- " . Il^w .........I f-Z _ 1 Mt4 by Date | Checked by ( ! . 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