Advantages of high and low pressure depropanization.

You can find many articles on this by searching on forums; it’s mainly used to prevent scaling in the tower bottom – by using a low-pressure tower, the temperature at the tower bottom can be reduced, thus preventing coking

The function of the high and low pressure towers is to raise the condensation temperature at the top of the tower; they can be cooled using cooling water instead of propylene refrigerant； At the same time, the temperature of the tower bottom is reduced by heating it with quench water, thereby eliminating the need for low-pressure steam. Due to the very high reflux ratio in this reactor, energy consumption is high. So the energy-saving effect is very good.

Do you know anything about the deethanizer and liquefied gas distillation tower in methanol-to-gasoline production? What are the typical operating conditions for those towers?

I only handle the olefin separation part. Coal-to-oil and coal-to-gas processes mentioned earlier are not applicable here. So I don’t know much about it.

This post was last edited by tonyaiwy on 2012-12-20 at 13:37. The use of high and low pressure depropanization towers can reduce the polymerization rate in such towers, allowing for longer operating periods. A high pressure tower alone accelerates polymerization; whereas a low pressure tower installed separately requires a large amount of cooling energy, resulting in poor economic efficiency

This post was last edited by lsl343952854 on 2012-12-20 at 15:19. Of course it can be set up as one tower, as long as your factory doesn’t care about energy consumption, efficiency, or safety. Propane and propylene have similar physical properties, which makes separation difficult. If you have the means, you can use APSEN to simulate the separation of these two substances. You will find that if a single tower is used, its height will be very high, around 130 meters. Such a tall tower presents difficulties in terms of initial construction and installation, as well as maintenance during its subsequent operation. On the other hand, the energy consumption required for a single tower to separate propane from propylene is quite high. Therefore, through the relentless efforts and research of scientists to optimize the processes, the use of high- and low-pressure dual-propane removal towers is currently the mainstream technology in various factories. The twin towers not only reduce the height of the towers, but more importantly, they lower energy consumption. Put simply: reducing energy consumption is the beginning of making money; therefore, factories are willing to use twin towers to earn more profit. And they are unwilling to use a single tower and keep losing money indefinitely. Moreover, there are many papers on this topic; you can search for them in Chinese journals such as Wanfang and CNKI, or look for them in foreign-language sources. I believe there will be a lot of relevant materials and literature.

Which aspect of olefin separation do you work on?

MTO also has large-scale ethylene production. Sometimes I come into contact with OCC, PDH, and some similar projects.

Thank you! You work in design, right?

In MTO separation, propane is used to absorb ethylene in order to separate methane; methane is polar, ethylene is polar as well, while propane is non-polar. Then doesn’t ethylene remain insoluble and get lost as a result? What is the reason?