How to deal with an increase in the inlet pressure of the synthesis tower?

1) Should the temperature of the synthesis tower be increased? 2) Adjust the hydrogen-to-carbon ratio of the gas fed into the tower. 3) Adjust the vent volume. 4) Whether the previous system was overpressured. 5) Reduce the inlet temperature of the circulation section.

In the synthesis of methanol, whether a high-pressure or low-pressure production process is used, there is a equilibrium pressure for the reaction. This pressure level remains relatively stable during normal operation. If an increase in the pressure at the inlet of the synthesis tower is observed, there could be several possible reasons for this. (1) As the catalyst reaction temperature drops, the synthesis reaction deteriorates or even worsens; meanwhile, fresh gas continues to be fed into the tower, causing the system pressure to rise, potentially leading to overpressure. Solution: Identify the cause of the temperature drop and take proactive measures to address it, such as shutting down auxiliary lines, cooling shock auxiliary lines, or reducing the circulation volume. If the system pressure exceeds the limit, it can be appropriately reduced or vented. (2) An increase in the CH4 content in the recycle gas leads to a decrease in the partial pressures of H2, CO, and CO2, affecting the methanol synthesis reaction; this is also one of the reasons for the rise in the pressure at the inlet of the synthesis tower. Solution: Increase the amount of air released after the tower appropriately (which can be recycled to the gas production section), or ask the gas production section to reduce the CH4D content in the fresh gas. (3) A sudden decrease or interruption in the circulation gas flow generally also causes an increase in the pressure at the inlet of the synthesis tower. Solution: Identify the cause of the reduction or interruption in the circulation air volume. Generally, apart from electrical system failures or the activation of interlock devices due to a lack of lubricating oil that causes the circulation pump motor to trip, such issues are all caused by equipment defects. For example: damage to the valve plates of the intake and exhaust valves in the cylinder, or to the piston rings ； Impeller damage ； Leak in the bypass valve of the circulation pump ； Due to reasons such as air leakage in the safety valve that controls the pressure difference of the circulation pump, it is necessary to closely monitor the system pressure and the temperature of the catalyst in the synthesis tower until the fault is resolved. If the process parameters cannot be maintained, production should be reduced or the plant should be shut down. (4) The poor water cooling effect of the syngas leads to poor synthesis reactions, which in turn causes an increase in the pressure at the inlet of the synthesis tower. Solution: Increase the cooling water flow in the water cooler; in case of a water supply interruption due to an accident, stop the machine. (5) Other factors, such as adding more high-pressure compressors to increase the amount of fresh gas without notifying the synthesis tower operator in a timely manner, can also lead to an increase in the inlet pressure of the synthesis tower.