In response to a requirement to provide a low-capital, low operating cost solution for the treatment of steam cracker spent caustic, BP Chemicals Ltd. (BPCL) and Stone and Webster Engineering Ltd. tSWElJ have jointlly developed a Low Pressure Wet Air Oxidation Process.
The first of these units has been in operation at the BPCL Grangemouth, Scotland facility for the last three years. In that time, it has demonstrated totally effective suode removal, sutpassing design targets, and producing a neutralized effluent well within the allowable discharge consents for the site. m e Grangemouth unit is designed to treat the spent caustic @fluent from two crackers with a combined capacit?/ of 600 KTA (current(y being expanded to 700 KTA).from both liquid and gas, feedstock.$. A sign@ant feature of the installation has been the extreme& high level qf reliability and availability, ensuring troub1e;free operation and full compliance with effluent consenl levels mandated by the regulatory authorities. At the same time, the unit has demonstrated very low opemting and maintenance costs. me design basis and initial commercial experience was presented at the AIChE Spring National Meeting in April 1994 [l]. mbi s paper concentrates on the operational history of the Grangemouth unit, highlighting the process developments and improvements that have been made in the last three years.