What kind of chemical additives are used in the DCU besides Antifoam ? Where are they used and for what ? We have two DCU units and we use only AE of 100,000 cST. We observe corrosion products in the filter of Diesel Hydrotreating. Our main tower has packing beds (AISI 316). Our feed (VR) has low súlfur (< 1 %), but high content of nitrogen . We had measure cyanides in the main tower sour water and the content is low (+/- 0,2 ppm). Is it common to use any chemical additives to prevent corrosion ?
AF comes on 12.5k cSt all the way up to 1M cSt. Their are benefits and costs to each level in terms of effectiveness, cost, and Si carryover. It depends on your injection practices, feed foam tendency, and Si carryover + bed protection downstream to reach an optimism decision.
Other chemicals include blowdown demulsifiers, APS for ovhd corrosion, and various antifoulants for HX and heaters. There are other niche applications of chemicals but they are one off’s.
RE Cyanides, water wash is effective for piping but H2 blistering in the ovhd drum can persist and should be inspected for during TAR or online (diffusion testing).