THE IMPRACTICALITY OF REQUIRING 99.95 RECOVERY EFFICIENCY OF CLAUS SULFUR RECOVERY UNITS

摘要

In 1976, the USA Federal Environmental Protection Agency (EPA) promulgated into law the "Standards of Performance for Petroleum Refinery sulfur Recovery Units" (40 CFR Part 60, Subpart J) which requires any refinery-located Sulfur Recovery Unit (SRU) of 20 LTPD size, or larger, to achieve an overall sulfur recovery efficiency equivalent to 99.95%. Then in 1985, the USA EPA promulgated into law the "Standards of Performance for Onshore Natural Gas Processing: SO_2 Emissions" (40 CFR Part 60, Subpart LLL) which requires any onshore gas-plant-located SRU of 300-500 LTPD size, or larger, to achieve an overall sulfur recovery efficiency of 99.0-99.5%.Today, the above regulations are considered excessively stringent. It is much more practical and reasonable to require SRU's to achieve a sulfur recovery efficiency of 99.0-99.4%. Several SRU Tail Gas Clean-up Unit (TGCU) Processes, not even known in the 1976-1985 time period, are now readily available to achieve these lower recoveries (99.0-99.4%), at about one-third (1/3) of the capital cost of TGCU's which can achieve the 99.95% recovery, I.e., the SCOT or SCOT-type TGCU's. Many additional benefits can be realized from these lower-cost TGCU's, such as: (1) less energy consumption, (2) lower CO_2 production/emissions from the stack, (3) much simpler operations and lower operating costs, (4) lower maintenance costs, and (5) higher "on-stream" factor, resulting in more reliable operations, etc. Fossil-fuel-fired electric power generating plants (burning medium-high sulfur coal) can be located in close proximity to a gas plant or refinery, and are required by the EPA to abate only 90%, or less, of the SO_2 emissions from their stack. This situation is not fair, equitable, or just. How can the Federal EPA justify or explain such a discrepancy? The truth is "they probably cannot". The Petroleum Processing Industry should petition the Federal EPA to revisit, review, and revise these out-dated and unfair regulations promulgated into law some 20-30 years ago. SRU sulfur recovery efficiencies of 99.0-99.4% are much more reasonable, and should be adopted as soon as possible.