The amount of methanol sprayed is reduced
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A stream of methanol needs to be injected before the transformed gas enters the E01 heat exchanger in the low-temperature methanol wash unit, with a design flow rate of 1050 NM/h. Recently, the flow rate has gradually decreased; it’s now only 300 cubic meters left, and the valves are all open. Discuss the impact on the system
The purpose of spraying methanol is to lower the freezing point of saturated water in the shift gas; since there is a cryogenic heat exchanger before it reaches the main scrubber, where the temperature is even lower, ice formation can occur in that heat exchanger, which in turn reduces its heat exchange efficiency – that is the main consequence.
As long as the water in the gas cannot freeze, that’s sufficient
By observing the pressure drop of the treated gas after entering the low-temperature methanol wash, the heat exchange efficiency can be assessed initially.
The purpose of this methanol spray is primarily to prevent the condensed water in the shift gas from clogging the heat exchangers. The flow rate generally does not decrease as the volume of gas decreases; if it does decrease, it is necessary to find the cause and address it promptly. Before that, pay close attention to the pressure difference in the heat exchanger after methanol spraying to see if there are any significant changes; a rapid increase in the pressure difference indicates that the amount of methanol sprayed is insufficient. If the pressure difference changes only slightly, with a minor increase and a continuing upward trend, the issue of low spray volume should be addressed promptly; if there is no change in the pressure difference, it can be dealt with during maintenance.