We run our coker feed tanks at around 385 ºF and we have vapors being generated with high H2S concentrations that cause odors. We have had odor complaints before, so we would like to address this issue. The tanks are atmospheric tanks that are nitrogen-blanketed. The vapors are mostly nitrogen with high concentrations of H2S (4000 ppm), traces of mercaptans, and traces of hydrocarbons.
Right now, we have a system in place for two of our 5 coker feed tanks that consists in water eductors pulling the vapors from the tanks. The water scrubs the vapors and the original idea was that the water itself would remove the H2S. Recently, we have added caustic injection to the water to improve the removal of H2S. Because the water scrubbing system is not very reliable (heavy hydrocarbons get condensed by the water and plug up the lines), we have not been able to test the performance of the caustic.
Does anybody have a better solution for treating these type of vapors? Do you have any other resources who may have experience with this issue and who have implemented some type of system to solve it?