Nitrogen consumption in low-temperature methanol washing
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May I ask the experienced colleagues whether pressure control with low-pressure nitrogen is still necessary for the acidic gas coming out of the regeneration tower in low-temperature methanol washing? And what determines the amount of nitrogen to be used?
Although the pressure in the regeneration tower is not directly related to the low-pressure nitrogen in the concentration tower, there is an indirect relationship; if the amount of nitrogen in the gas from the concentration tower is too low, it will cause the pressure in the regeneration tower to rise. Stripping nitrogen is primarily used to concentrate hydrogen sulfide in the acidic gas in order to support the Claus sulfur recovery process; the amount of nitrogen required is determined based on the concentration of the acidic gas.
It’s not necessary; the acidic gas nitrogen supplementation pipeline should be used for pressurizing the system during startup
The acidic gas exiting the regeneration tower needs to have its pressure controlled using low-pressure nitrogen. This is done primarily to maintain stable pressure when the pressure in the regeneration tower is too low; the exact amount of nitrogen used depends on practical operational experience. In fact, in actual operations I believe it is not advisable to use nitrogen to increase the pressure when the regeneration tower’s pressure is low, as nitrogen is an inert gas, and its presence in the sulfur recovery process can affect the catalyst’s activity and reduce the reaction rate. Therefore, when the pressure in the regeneration tower is low, the valve that allows acidic gas to flow into the hydrogen sulfide concentration tower can be closed, thereby increasing the amount of acidic gas sent to sulfur recovery and raising the pressure
There is no direct relationship between them. The acidic gas from the regeneration tower comes from the hydrogen sulfide concentration tower, after a large amount of carbon dioxide has been removed from it; its volume increases as a result of this concentration process
The pressure of the Claus gas leaving the reactor section is controlled by a pressure control valve; there is no need to introduce low-pressure nitrogen. The role of the stripping nitrogen is to flash and strip CO2, thereby indirectly regulating the concentration of the Claus gas. Only in emergency situations, such as a low-pressure steam failure that causes rapid condensation in the thermal regeneration tower, is low-pressure nitrogen introduced into the tower to prevent a negative pressure from developing there.
I don’t think a regeneration tower requires nitrogen control; steam is used to control the tower pressure, with nitrogen being used only during the initial startup process...
Nitrogen is only used for pressurization when the system is first started up
After parking or a disruption in the heat source, cool negative-pressure air is introduced into the tower for N2 sealing.
Generally, the pressure in the regeneration tower is controlled by an AB valve; when the pressure is high, valve A opens to fill the tower with nitrogen, and when the pressure is low, valve B opens to release pressure. It can also be controlled manually, using a hydrogen sulfide concentration line to return the hydrogen sulfide exiting the device to the concentration tower, gradually increasing the pressure of 1# xb123
After the vehicle stops or the heat source is disconnected, cooled negative-pressure air is introduced into the tower; N2 is used for sealing. This is also beneficial for the four pumps, as it prevents cavitation under high temperature and low pressure conditions.