Methanol off-gas is used as a hydrogen source for the hydrogenation of light benzene
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Comprehensive resource utilization plan for coal chemical parks: Methanol production from coke oven gas – the components of the off-gases are H2 at 65-68%, CO at 3-5%, CO2 at 5-7%, and CH4+N2 at 18-20%. It is necessary to recover these gases; the volume of off-gases is 13,000–15,000 Nm3/h (for 200,000 tons of methanol per year). The hydrogen content in these off-gases is higher than that in coke oven gas. Could they be used as a hydrogen source for the hydrogenation of light benzene? This would not only help conserve coke oven gas and increase the supply of raw materials for methanol production but also ensure that all components of the methanol off-gases are utilized effectively. Moreover, the exhaust gas from light benzene hydrogenation can be mixed with excess methanol off-gas to increase its calorific value for use in heating coke ovens; it can also replace some of the coke oven gas used in methanol production. Achieve the comprehensive utilization of coke oven gas, methanol off-gas, and light benzene hydrogenation exhaust gases to improve economic efficiency and promote a circular economy. Please, fellow sailors, discuss whether this plan is feasible!
It’s very necessary! It’s completely feasible! That’s exactly how the projects we plan and design are carried out! This is a good approach for implementing a circular economy. Furthermore, using PSA for hydrogen extraction from self-relaxed off-gases results in a shorter purification process compared to that used for hydrogen extraction from coke oven gas, with lower investment costs. The exhaust gases can be reused or recycled, which is an excellent approach that not only saves energy but also makes full use of resources, enabling the complete utilization of hydrogen contained in coke oven gas.
It’s completely feasible! This is a very good approach for energy utilization. It extracts hydrogen with high added value while reusing the heat from exhaust gases, making it an excellent recycling solution.
Hydrogen is recovered using a PSA unit; the hydrogen recovery rate can reach 90%, and the purity of the hydrogen can reach four nines, which fully meets the required standards.
This approach enables the effective utilization of off-gases; in pressure swing adsorption units, hydrogen can be produced for the hydrogenation of benzene and the hydrogenation of tar to manufacture diesel and gasoline； The extracted carbon-rich gas can be added to the conversion gas in order to improve the composition of the feed gas used for methanol synthesis. This approach effectively addresses the issue of a high hydrogen-to-carbon ratio in the feed gas derived from coke oven gas, increases methanol production, makes effective use of waste gas, and promotes rational resource utilization.
OP, of course it’s possible – that would be great! Our PSA system uses methanol off-gas to produce hydrogen; compared with the process of producing hydrogen from coke oven gas, it eliminates the need for desulfurization, naphthalene removal, and compression processes. Additionally, depending on the quality requirements for hydrogen, a hydrogen deoxygenation unit can be used, thereby saving significant investment costs. Moreover, since the methanol off-gas is relatively clean, the PSA operates quite stably – so why not do it? Our PSA uses methanol off-gas to produce hydrogen, and it has been operating continuously for 7 months without any issues.
As an extension of the coking industry chain, a sustainable circular economy is desirable; Kailuan Zhongrun Coal Chemical Company has launched this project, which is now in operation.
Is that how our company does things? However, a problem has arisen: due to the design of the PSA, the concentrations of carbon monoxide and carbon dioxide in the exhaust gas are not very high, which results in poor efficiency in adding carbon through methanol.
That’s great; the gas produced is cleaner than coke oven gas, and its pressure is high. And also make the most of things to save costs