Sour Water Optimization: A Key to Refinery Sustainability

A: A feels uncomfortable because velocity is low and bulk pH is alkaline, but that's exactly where NH4HS comes out of solution and creates aggressive local chemistry. That's the real driver in sour water circuits. B borrows intuition from wet gas and amine systems; here CO2 is largely neutralized by ammonia, so it doesn't set the corrosion rate. C sounds plausible if you've lived in crude overheads, but chlorides aren't the controlling species unless you have significant chloride ingress and evaporation. D is a real damage mode in sour service steels, yet it piggybacks on corrosion reactions; without NH4HS attack generating hydrogen, blistering doesn't just appear on its own.

A: A comes straight from first principles: 100 m3/h is ~27.8 kg/s, multiply by CP and 40 K and you land just under 5 MW. That's the right scale check. B sounds refinery-real, but latent heat isn't in play unless you're boiling a large fraction; strippers heat, they don't vaporize the bulk liquid. C mixes in process integration thinking, yet the question isolates the heater duty, not net energy balance. D feels safely conservative, but doubling duty without a physical basis is how heat exchangers get oversized and control suffers.

A: A reflects the intent of the standard: controlling SSC risk when steel sees wet H2S, not just in wells but anywhere the mechanism exists. B is the overreach many make—MR0175 isn't a blanket refinery rule, it's mechanism-driven. C confuses company specs with law; regulators don't cite MR0175 directly for utilities. D flips the chemistry; higher pH actually reduces hydrogen evolution rates, it doesn't amplify them universally.

A: A feels pragmatic, but timing doesn't guarantee correctness; both documents can lag reality. B accepts schedule pain to control risk—fail position on a stripper bottoms valve can swing between flooding and dry-out scenarios. C is a rule-of-thumb imported from hydrocarbon service; here fail-open might be deliberate to protect the reboiler. D overestimates the PLC; loss of air defeats logic, leaving you with pure valve physics.