Low-temperature methanol washing, why is gas stripping nitrogen introduced in advance before gas conduction?

The purpose of introducing stripping nitrogen in advance is to pre-cool the raw gas pipeline and cooler.

The function of stripping nitrogen is to break the balance, provide cold energy, lower the temperature of methanol, and make hydrogen sulfide more concentrated.

The main purpose is to let the gas-lifted nitrogen pass through the raw gas cooler and pre-cool the raw gas cooler, which has nothing to do with the raw gas pipeline!

The raw gas cooler has already cooled two streams of materials before the gas is introduced to extract nitrogen, so it is not a pre-cooled raw gas cooler. When using gas-lifting nitrogen before gas conduction, the main consideration is the loss of methanol. Because it is alcohol methanol at this time, our tail gas is directly vented. In addition, stripping nitrogen can take away cold energy. The amount of stripping nitrogen we introduce at the beginning is less than the normal value. The normal value will be set after the gas is introduced and starts to cool down.

There are several uses for inflating the nitrogen gas. First, it provides the concentration tower with pressure to ensure the pressure at the pump inlet. Second, it strips the CO2 still contained in the methanol. If you do not pressurize the methanol when driving, and do not add gas to lift the nitrogen. If you stop to maintain pressure, the methanol in the CO2 product tower still contains more CO2, and the methanol pump at the bottom of the tower will gradually heat up due to the shutdown time. At this time, it is easy for air trapping and cavitation to occur when the cold liquid enters. If the pressure is not maintained or the initial startup is started, a small amount of nitrogen can be introduced to ensure the pressure of the concentration tower. Third, the gas stripping takes away part of the cooling capacity to ensure that the imported raw gas heat exchanger can be pre-cooled, preventing the large amount of conversion gas from being connected during operation and not being able to be cooled. If the outlet temperature is high, the amount of water brought into the scrubber will increase, which will affect the methanol absorption effect.

There is a problem with what was said on the 5th floor. Generally, gas stripping nitrogen is introduced 30 minutes in advance before gas connection. At this time, the other two logistics do not exist.

This post was last edited by happyday0912 on 2010-7-15 17:59 and replied to 7# wgonline. Before gas conduction, the T0501 tower and T0502 tower are filled with nitrogen and pressure-maintained. The nitrogen at the top of tower 1 passes through the start-up line and finally passes through E0501. The top of tower 2 also passes through E0501 at the end. Both materials are pressure-maintained nitrogen. At this time, the hydrogen sulfide concentration tower is under normal pressure (not pressurized). Ours is a 6-tower process, from Dalian University of Technology. It's just that the flow rate of pressure-holding nitrogen is small, but it's definitely there. The CO2 goes to the soda ash plant after being washed in the T0506 tower, and the tail gas is vented after passing through the E0501. We put it in before the air conduction, and it didn't take half an hour, ten minutes at most, because a small amount of conversion air would come in as soon as the bypass was opened, and it would take half an hour to open the bypass and the large valve. I just started working, Zhengshi * Yes, thank you all for your advice.

Before gas conduction, our 1/2 tower is pressurized and maintained with nitrogen instead of being constantly inflated. There are two main purposes for using gaseous nitrogen in the gas guide tube. One is to pre-cool ； One is to stabilize the stripping tower in advance.

I agree with the point above. There are two main purposes of nitrogen stripping in the H2S concentration tower.: One is to encounter cold, and the other is to stabilize voltage.

Reply 1# gxx1008 I think so: 1 In order to strip the carbon dioxide out of methanol. 2 Since the cooling capacity balance of the system will be destroyed after degassing, gas nitrogen is added to obtain more cooling capacity.