Why does the methanol synthesis gas need to be circulated before being fed into the synthesis tower?

Because the gas entering the tower reacts once within the synthesis tower, it can be converted by about 5 percent. So it needs to loop

This is because the one-pass conversion rate in the methanol synthesis tower is only 3%-6%, and moreover, the CO content in the fresh gas is too high, resulting in a large amount of reaction heat being generated; therefore, the amount of recycle gas is used to remove this substantial amount of reaction heat.

The main reason is the low one-way conversion rate in methanol synthesis; removing heat serves only that purpose, and water is the primary means for removing heat.

This post was last edited by 654262293 on 2011-5-9 at 11:15. After the loop unit stops operating, there is no circulating gas, and venting is not allowed in front of the methanol synthesis tower. Can you control the peak temperature of the catalyst bed? If you think you can do it, go ahead and give it a try! !

Have you experienced a stuck tower? Vent in front of the tower! Some designs do not have a vent in front of the tower. Description of a certain process package! Once the recycle gas compressor stops, the temperature of the synthesis tower can be fully controlled as long as the recycle water pump keeps running. The temperature of the synthesis tower can be controlled through the drum, in the second case. When the circulating water pump fails, the standby pump cannot start automatically, and the circulating gas system shuts down as a result; in such a situation, would you use circulating gas to cool the synthesis tower? In towers for gas-to-gas heat exchange, such as Linda towers, the volume of circulating gas has a significant impact on the tower temperature. Once the circulation of gas is interrupted, it is necessary to release pressure immediately to prevent gas flow; otherwise, the temperature inside the tower will rise sharply. Pressure release is essential in such situations, and if conditions permit, nitrogen can be introduced as well. Nevertheless, the heat generated by the tower still needs to be removed using a waste heat exchanger. The best practice is generally to increase the circulation rate to its maximum, and control the temperature of the synthesis tower using the inlet temperature or the drum pressure. This helps to ensure uniform bed temperature; simultaneously, an increased amount of gas enters the tower, allowing for full utilization of the active components. I think each set of devices has its own unique design philosophy. Whether it is the circulating gas volume or water, both play a role in removing heat from the synthesis tower; both help to control the temperature of the tower, it just depends on what control method and type of tower are preferred in the design. I’m new here; if I say anything wrong, I hope the Tianwen moderators and all the experienced members will not take it personally. I’ve decided that from now on I’ll read and learn more, and try to express my personal opinions as little as possible, so as not to embarrass anyone.

The one-tower synthesis achieves a one-pass conversion rate of 30% to 50%, while multi-tower synthesis can reach over 60%. To ensure more complete conversion of the feed gas, it is necessary to recycle the feed gas; by reducing the amount of off-gas, the overall conversion rate is approximately 95% to 98%. The conversion rate, based on alcohol yield, is approximately 93%–96%.

It’s a bit confusing. Generally speaking, the methanol synthesis reaction is a volume-reducing and incomplete chemical reaction, with a conversion rate ranging from 6% to 13%, depending on the process used. In order to allow the gases that have not participated in the reaction to react again, it is necessary to increase the pressure of these gases and send them back into the tower for further reaction. When the pressure of the fresh gas is low, the pressure of the gas must be increased to create the conditions necessary for methanol synthesis within the tower. Additionally, the circulation rate of the compressor also serves to remove the heat generated by the reaction. Under constant conditions, increasing the backflow or anti-surge valve of the compressor will raise the temperature of the synthesis catalyst; you can give it a try if you don’t believe it. Lastly, the space velocity also determines the contact time between the synthesis gas and the catalyst, which in turn affects the reaction rate