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Before the raw coal gas enters the main washing tower, methanol is sprayed to prevent freezing. Our design calls for 22 cubic meters of gas to be mixed with 0.3 cubic meters of methanol. I would like to know what the current ratio is. It has been observed that the pressure difference in the heat exchanger increases gradually after spraying methanol; this suggests a possibility of freezing. Initially, it is believed that there is a problem with the methanol spraying nozzles, which results in uneven mixing of methanol and raw coal gas and leads to localized freezing. Does anyone have any information related to these nozzles? Thank you.
I’m not sure what kind of process you use; here, the shifted gas is washed in a water scrubber, and after that, the gas at a temperature of <40°C enters the low-temperature methanol washing unit. The designed gas flow rate is 174,000 Nm3/h, with a methanol spray volume of 0.72 m3/h.
Luchi, it seems we’re using too little methanol in the spraying here
The amount of methanol used for spraying generally does not change as the load is adjusted. I have seen cases where the shift gas is cooled further before entering the low-temperature methanol wash unit, and then spraying methanol is employed after separation; in such cases, the amount of methanol used for spraying is relatively small.
Our system has a low-pressure gauge reading of around 250,000; 1.7 cubic meters of methanol are used for spraying, and these systems are activated half an hour in advance. We have never encountered such a problem; it seems that the amount of methanol used for spraying in your system is too small
The amount of methanol used for spraying is too low; we use 170,000 units, with an alcohol spraying rate of 1 M3/h. When the spraying nozzles operate at such a low rate, the atomization effect is poor, and the ability to capture moisture is also weak.