(74a) Decreasing Emissions and Improving Performance at Dow's LHC7 Ethylene Plant

Starting in 2000, increasingly stringent air quality requirements from the Texas Commission on Environmental Quality (TCEQ) for ozone non-attainment areas forced Dow to consider various options for reducing NOx emissions at its Freeport, TX facilities, located about one hour south of Houston and included in the Houston-Galveston non-attainment region. This site was originally started up in 1941 and has facilities of varying ages, including ethylene plants started up in 1973 and 1995. The older ethylene plant, LHC-7, was a prime candidate for NOx reduction. This paper describes the site-wide study to reduce NOx emissions, the various options for equipment replacement, modification and shutdown considered and the improvements made to the LHC-7 ethylene plant to reduce NOx emissions. These improvements included replacement of a gas turbine driver for the propylene refrigeration compressor with a steam turbine and construction of an all-new furnace section to replace the existing furnaces. Economic, energy efficiency and NOx reduction results of the work will be described.