Hydrogenation of light hydrocarbons recovery
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The hydrogen content in the low-pressure gas and waste hydrogen I have is very high (over 70%). I am considering recycling this hydrogen. Although we have hydrogen production equipment as well as PSA units, I’m looking for ways to make the most use of this hydrogen. The current process involves feeding the waste hydrogen, low-pressure gas, and acidic gas from the stripping tower into the dry gas desulfurization system; even with this approach, the hydrogen content in the dry gas remains above 40%. This gas then goes to the inlet of the pressure booster, or it can be used as a raw material for hydrogen production. Do any experts have any good suggestions for process modifications?
It mainly depends on the composition; if the content of low-molecular-weight gases and waste hydrogen is high, what are the other components? Can it be added directly to the PSA inlet? Is the hydrogen content high in the acidic gases from the gas column? If it’s very low, there’s no need to worry about it
Originally, we desulfurized the gas along with other gases before sending it to the PSA unit; later, a new low-pressure gas desulfurization tower was installed to carry out desulfurization separately before sending the gas to the inlet of the reforming compressor.
In my opinion, 1. Although the hydrogen content in the mixture is high, reaching over 70%, it is a mixture of waste hydrogen, light fractions, and acidic gases from the top of the tower; as a result, the H2S content is certainly high. If this mixture were to be fed directly into a PSA unit for separation and purification, the hydrogen sulfide would end up in the converter where it would burn and then be released into the atmosphere. From the perspectives of corrosion control and environmental protection, this approach does not seem feasible. 2. If the hydrogen production facility includes raw material pretreatment, hydrogen will need to be supplied in any case; therefore, a 40% H2 content is not actually that high. The issue lies in whether this will affect the fuel composition in the main gas pipeline, leading to a decrease in calorific value and thus an increased load on the burners of other furnaces!
Thank you for the advice. I originally planned to use dry gas as a raw material for hydrogen production, but now it’s being fed directly into the rich gas stream. . .
Low- and high-pressure gases enter the desulfurization tower for desulfurization, and then are pressurized for PSA adsorption to produce hydrogen gas. . . . . The situation described by the original poster is so similar to mine. . .