What is the COD level of acidic water from catalytic cracking?

This post was last edited by longziyun on 2018-11-25 at 11:07. The water in the acidic water produced during catalytic cracking comes from three sources: first, the water contained in the feedstock residue oil (in small amounts); second, the steam injected into the reaction and distillation systems (which constitutes the majority of the water); third, a portion of water generated as a result of dehydration reactions during catalytic cracking (in small amounts). These three sources of water enter the top condenser and coolers of the distillation tower in the form of steam, where they condense to form sulfur-containing ammonium wastewater, commonly known as acidic water. Since the catalytic cracking reaction effluents are washed, the acidic water contains not only highly acidic carbonate ions and S2-, but also less acidic water-soluble volatile phenols. It also includes alkaline NH4+, as well as other water-soluble salts generated during the cracking process, primarily sodium, iron ions, and complex ions of vanadium, chromium, nickel, antimony, etc. There are also small amounts of water-soluble organic compounds such as alcohols and aldehydes, as well as light contaminated oil that remains due to the failure to fully separate oil from water. The composition of this acidic water is complex, and there are many factors that affect its COD value. Depending on factors such as the composition of the feedstock residue oil, the catalytic cracking process, reaction temperature, oil-to-catalyst ratio, and steam injection volume, the COD value of the resulting acidic water varies, making it difficult to make comparisons. As far as I know, most are probably between 2000–7000 mg/L.

What process? Coking? What kind of oil? I’m not sure whether it’s high sulfur, high ammonia nitrogen, or high pH that causes the emulsification of oil and water

It mainly depends on the nitrogen content and type in your raw materials, as well as whether ammonia is added at the top of your distillation tower