Investigation on the influence of synthetic methanol feed gas composition on yield
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An analysis of the recent changes in the production volume of methanol plants suggests that the carbon dioxide content in the feed gas should be above 1.2% in order for the catalyst to exhibit high activity; the lower the methane content in the feed gas, the higher the methanol production. Additionally, the hydrogen-to-carbon ratio in the feed gas must be such that it is greater than 3 at the inlet of the synthesis tower in order to achieve high methanol yields. :handshake I hope everyone will share their experiences so that we can learn from each other – what is an optimal hydrogen-to-carbon ratio, and what are the consequences of imbalances? Sorry, I forgot to mention above that there are two main discussion points regarding the hydrogen-to-carbon ratio: 1) Analysis of the hydrogen-to-carbon ratio at the compressor inlet; 2) Analysis of the hydrogen-to-carbon ratio at the synthesis reactor inlet. What is a reasonable value based on these analyses? If you all think this topic is worthwhile, please help by giving it a thumbs up :victory: and a handshake :handshake. This post was last edited by “The Earth keeps spinning” on February 15, 2009, at 16:16.]
A value greater than 3 will cause a significant accumulation of hydrogen, increasing the energy consumption of the compressor. Generally between 2.05 and 2.15
The optimal hydrogen-to-carbon ratio is 2.0! If it’s too large, it’s of no use; it also results in unnecessary work being done, increasing energy consumption! It increased costs!
A hydrogen-to-carbon ratio of 2.05–2.15 is preferable. 2 is the theoretical value, but in production a slight excess of hydrogen is beneficial for the conversion rate of CO; the excess hydrogen can also be recovered for reuse. A CO2 content of 2.5 is better.
I’m sorry; I forgot to mention it above. The two main topics related to the hydrogen-to-carbon ratio are: 1) analysis of the hydrogen-to-carbon ratio at the compressor inlet, and 2) analysis of that ratio at the inlet of the synthesis tower. Which one should be used as a reference? I’ve added this to the topic again – are you all referring to the analysis of the hydrogen-to-carbon ratio in the fresh gas at the compressor inlet?
It’s okay, I can handle it on my own. Is there any expert who can give guidance? This post was last edited by xuqinger on 2009-2-17 19:14]
The hydrogen-to-carbon ratio of 2.05–2.15 refers to the analysis of the fresh gas at the compressor inlet. Since CO2 is adsorbed on the catalyst much more rapidly than H2, in order to achieve the hydrogen-to-carbon ratio required for the reaction, the hydrogen-to-carbon ratio of the feed gas at the entrance of the synthesis tower is generally around 5–6 (depending on the system circulation rate)
A hydrogen-to-carbon ratio of 2.05–2.15 is considered reasonable, but most coking plants use coke oven gas to produce methanol, in which case the hydrogen-to-carbon ratio is much higher, around 5–6. A high hydrogen-to-carbon ratio can lead to waste of hydrogen and an increase in emissions of vent gas. To make rational use of resources, some manufacturers add carbon to the feed gas, significantly improving the utilization rate of hydrogen.
It is generally between 2.05 and 2.15. Generally, a hydrogen content lower than this can cause carbon deposition on the catalyst. Excess hydrogen content leads to high energy consumption. Generally, an excessive hydrogen content requires carbon supplementation.
A hydrogen-to-carbon ratio of 2.05–2.15 is relatively reasonable; a higher ratio will lead to an excessive accumulation of hydrogen, increasing the energy consumption of the compressor.
A hydrogen-to-carbon ratio of 2.05–2.15 is a reasonable choice; too high a CO2 level results in excessive water production, a low content of crude methanol, and thus a low yield of pure methanol
The hydrogen-to-carbon ratio ranges from 2.05 to 2.15, and the CO2 content is greater than 1%; 8% is the theoretical value, with it generally should be kept between 2% and 5%
In methanol synthesis, the stoichiometric ratio of hydrogen to carbon monoxide is 2, while the ratio to carbon dioxide is 3. When both carbon monoxide and carbon dioxide are present, it is best to maintain the hydrogen-to-carbon ratio in the feed gas between 2.05 and 2.15; keeping this ratio slightly above 2 helps to reduce the formation of iron carbonyl and higher alcohols, as well as to extend the lifespan of the catalyst. However, an excessive amount of hydrogen leads to a buildup of hydrogen, increasing the energy consumption of the compressors. Maintaining a certain amount of carbon dioxide in the syngas also helps to preserve the high activity of the catalyst, reduces the heat generated by the reaction, and helps to maintain the temperature of the catalyst bed. Yet, too much carbon dioxide results in an increase in the water content in the crude methanol, leading to a decrease in methanol production and an increase in the energy consumption associated with the distillation process. Typically, the carbon dioxide content at the compressor outlet ranges from 3% to 5%, while that in our company is 3.42%.
The amount of methane is constant, which can effectively suppress the occurrence of side reactions and is beneficial for the reaction of methanol. This is reflected in our company’s synthesis technologies; perhaps different technologies have different standards, and it’s not the case that fewer is always better. For reference only!
I’m more interested in what was mentioned upstairs. What’s the production process like where you are? What is its methane content? I feel that the lower the methane and nitrogen content, the better. Can we discuss it?
At the compressor inlet, the hydrogen-to-carbon ratio should be kept around 2–2.05. During synthesis, it is best to keep the inlet value around 4; this helps to protect the catalyst and improve the reaction while reducing the occurrence of side reactions
What the original poster is referring to is the hydrogen-carbon ratio of the gas fed into the tower, while the vast majority of replies provided use the optimal value for the hydrogen-carbon ratio of fresh gas as given in textbooks. In my opinion, the hydrogen-to-carbon ratio of fresh gas is determined by the raw materials and the gas production process; once these two factors are fixed, the range of the hydrogen-to-carbon ratio is also established, and it is generally difficult to adjust this ratio unless other suitable carbon or hydrogen sources are available as supplements. Regarding the optimal hydrogen-to-carbon ratio for fresh gas, the value of 2.05–2.15 given in textbooks cannot be applied universally; there is no theory that applies everywhere in the world, and adjustments should be made based on specific circumstances. In my opinion, it is more reasonable to focus on the hydrogen-to-carbon ratio of the gas entering the tower rather than that of the fresh gas. Last edited by Choosing the wrong career on 2009-3-10 21:02]
In my opinion, a hydrogen-to-carbon ratio of 2.05–2.15 is ideal; higher levels of carbon dioxide lead to increased energy consumption, and the methanol yield may not necessarily increase. Moreover, it’s not true that the lower the methane level, the better. Inert gases can help control the intensity of the synthesis process, preventing excessive temperatures – especially after replacing the catalysts!