OCR Text |
Show combustion devices, it is generally far more cost effective to centrally reduce the sulfur content of the entire fuel gas system. The regional regulation from the SCAQMD is outlined in Rule 431.1 and it sets the limits on the total sulfur concentration of gaseous fuels used or sold in the South Coast Air Basin. These limits may be summarized as follows: 1.) An 80 ppm limit is set on gaseous fuels which are sold across the plant boundaries. 2) A 250 ppm limit is set on landfill and sewage digester gas. 3.) An 800 ppm limit is set on gaseous fuels consumed onsite. Most of this fuel is refinery gas which is burned in boilers and heaters. New Regulatory Action A new regulation was arrived at through the joint efforts of the Western States Petroleum Association (WSP A) and the SCAQMD and Bechtel. WSP A is an LA Basin refining industry trade association which represents the industry collectively on issues of common interest. This is one of the first attempts at joint, cooperative rule-making between industry and the environmental authorities (SCAQMD) prior to the final drafting of an individual statute. Bechtel acted as an unbiased third party whose function was to develop a comprehensive summary of the technical, engineering and economic sides of the issue. This information was summarized into a Background Information Document (BID) which was formally submitted by WSP A to the SCAQMD prior to the legislative enactment date. The typical procedure in rule development by the SCAQMD first involves the generation of a BID by the SCAQMD on the proposed area of control. Affected industries or other interested parties can then submit their own analyses, or BIDs', as input to the legislative fact-gathering process. The resulting legislation ("new" Rule 431.1) limits the level of TOTAL sulfur in any industrial fuel gas, including Refinery Fuel Gas (RFG), to 40 ppm over any 4 hour averaging period. This new regulatory limit will become effective on May 1, 1993. The rule contains the same SOX equivalenqr provision as before. All of the LA Basin refiners will be revamping their Refinery Fuel Gas (RFG) systems to comply with the new LA Basin 40 vppm total sulfur regulation in the next 2-3 years. New units will probably be necessary for essentially all of the refiners; as the current average RFG sulfur level in fully integrated refineries is in the 150-200+ ppmv range. Study Results 1.) Existing Data and Analysis In the course of the WSPA technological and economic study, large quantities of RFG data were gathered from all of the LA Basin refiners. Measuring aU of the sulfur species requires complicated laboratory analyses using recently developed techniques. The refinery database that has been generated shows that refinery fuel gas (RFG) compositions vary widely in inorganic, organic and sulfur species. Concentrations of Carbonyl Sulfide (COS) and mercaptans (RSH's) were often higher than HzS, primarily in gases emanating from Fluid Cat Cracking (FCC) and Coking units. The RFG's also contained a number of other compounds not normally present in pure gaseous fuels, like olefins, CO, COz , Oz , <; +, Hz , etc. This diverse and widely variable array of components can cause various interferences with many potential desuifurization processes. -2- |