Document pBwRvrXEOoXV9m6xZ2L8777LE

(conoco) Interoffice Communication To From W. J. Weisenborn, Westlake, Louisiana K. L. Kennedy, Ponca City, Oklahoma oft ate Subject November 12, 1982 Ml--- Heavy Crude Project--The Effect on Waste Water Treatment Sf^tKe Lake Charles Refinery The effect of the Heavy Crude Project on the Lake Charles Refinery effluent has been calculated. The new permit values are generally expected to increase by about 10 percent over the previously calculated values for the sour crude case as a result of running heavy crude. This assumes that the State continues to follow the National Best Practicable Technology Effluent Guidelines (BPT). The increased permit values result from slightly higher coker and vacuum dis tillation rates. ' We have also calculated that BOD and suspended solids permit exceedances will likely occur after startup of the Sour Crude/Heavy Crude projects if no change is made to the present waste treatment system other than the planned addition of pretreatment flotation. Additional measures, such as removing the cooling tower blowdown from the waste water treatment system, will be required to prevent frequent permit exceedances. With the Heavy Crude project, higher charge rates are expected for the Vacuum Distillation and Delayed Coking units. These higher rates will affect the calculated permit values using the BPT Effluent guidelines as shown in Table I. Table II shows the predicted daily average BOD and suspended solids effluent values for the refinery Sour Crude/Heavy crude projects with and without cool ing water bypass. With the existing treatment scheme, effluent quality will drop significantly, mainly due to increased desalter water from CTU No. 3. BOD loading to the activated sludge unit will rise while ASU performance will de cline due to reduced residence time. It Is likely that the effluent BOD levels will be even higher than our calculated values since the ASU residence time will be low enough to cause severe hydraulic overloading (13.5 hours). The total suspended solids (TSS) effluent values will also increase slightly due to increased flow through the final DAF unit. Permit exceedances for both BOD and suspended solids will probably occur. Of course, how quickly the exceed ances occur after startup may depend on a variety of factors Including organic loading variations, upsets In the process units, amount of storm water to treat, etc. The effluent levels could be lowered to below permit values by changing to non chromate treatment of the cooling water or by adding a chromate removal process before discharging the cooling tower blowdown directly. This relatively low capital cost alternative would reduce effluent BOD and TSS levels dramatically by lowering the flow rates to the ASU and DAF units. Bypassing only a portion of the cooling water would greatly reduce permit exceedances, although the effluent quality would not be as good as that shown in Table II. W. J. Weisenborn Page 2 There may be other approaches to solving the problem although the cooling water bypass appears to be the most economically attractive approach. We are willing to sit down with you to discuss the effluent problem and possible solutions at your convenience. We understand that you plan to go ahead and submit the Sour Crude NPDES permit application. The Heavy Crude application will follow shortly. If you have any questions, please call Karen L. Kennedy' r Process Engineer Engineering Services Division Process Engineering Department ke Enc Vw j RGG:JSD:LES:KH P. W. Lashbrooke - Westlake J. W. Leigh - Westlake P. A. Madison - Westlake M. K. Sternberg - Westlake Approved File: EV-U92.16 MCD 000002452 TABLE I BEST PRACTICABLE TECHNOLOGY EFFLUENT GUIDELINES HEAVY CRUDE PROJECT LAKE CHARLES REFINERY Parameter BOD5 TSS COD Oil and Grease Phenolic Compounds Ammonia (as N) Sul fide Total Chromium Hexavalent Chromium Dally Average, Lb/Day 1,398 1,118 9,787 407 9.0 756 7.3 22 1.4 Dai ly Maximum, Lb/Day 2,517 1,755 18,862 763 18.6 1,663 16.3 38 3.1 Basis: The following projected production rates: Atmospheric Distillation Vacuum Distillation Desalting Fluid Catalytic Cracking Thermal Cracking Delayed Coking(1) BPSD 164,000 69,000 164,000 30,600 11,800 56,200 Notes: 1. From Heavy Crude Project Case No. 44, KLKtke MCD 000002453 Lb/Day BOD TSS TABLE II EFFLUENT DAILY AVERAGE BOD AND TSS LEVELS HEAVY CRUDE PROJECT LAKE CHARLES REFINERY WITH EXISTING TREATMENT SCHEMEC3) 5Q Percent 95 Percent Effluent Effluent Number (1) Numbe r (2) >755 >1,708 925 1,244 WITH COOLING WATER BYPASS 50 Percent 95 Percent Effluent Eff1uent Number Number 491 729 748 952 Notes: 1. The 50 percent effluent number (median value) corresponds to an effluent value which will be exceeded 50 percent of the time, 2. The 95 percent effluent number corresponds to an effluent value which will be exceeded 5 percent of the time. Effluent values are generally considered to be in compliance by EPA If the 95 percent effluent number is below the NPDES Daily Average permit value. 3. Existing treatment scheme with the new flotation facilities installed. KLKrke ttCD 00002