There is no way to provide a generalized method of calculating the amount of spent caustic (containing NaHS) produced in a refinery. There are quite literally hundreds of different refinery configurations processing hundreds of different crude oils, and hence hundreds of different streams (containing different amounts of sulfur) being scrubbed with caustic.
One must know the exactly what amounts of what streams containing what amounts of hydrogen sulfide are being scrubbed in a specific refinery.
I strongly suggest that you read the book "Aqueous Wastes from Petroleum and Petrochemical Plants", by M.R. Beychok, published by John Wiley in 1967. It is available in most good university libraries.
Milton Beychok
(Visit me at www.air-dispersion.com)
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