Methanol to hydrogen: methanol and water feed conditions
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In a methanol-to-hydrogen plant, what is the relationship between the feed rates of methanol, deionized water, and circulating fluid? But what the manufacturer provides is the density of the mixture of methanol and circulating fluid (measured value), which ranges from 0.915 to 0.922. Is this value sufficient? Could we discuss any references related to similar systems?
At the beginning of operation, the molar ratio of water to alcohol should be 2:1 in order to control the CO content in the crude hydrogen; once normal operation is achieved, the ratio should be 1.2–1.5:1. The density of the mixture should remain within the range specified by the original poster.
The mass ratio of water to alcohol in hydrogen production via methanol cracking can be controlled at 1.2~1.5:1 (m/m) for water to methanol. In actual production, it is sufficient to ensure a slight excess of water in the feed to the converter; an excessive amount of water leads to increased energy consumption, which is not desirable. The water-alcohol ratio in the circulating liquid indicates the degree of conversion; the lower this ratio, the better. Our control target is to keep the methanol content at no more than 8%, while for the conversion gas, we focus on controlling the levels of CO and CO2, with the requirement that CO+CO2≯20ppm and CO≯10ppm