Experts in low-temperature methanol washing, please come and analyze it
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Our plant uses Linde technology for low-temperature methanol washing; there is an ammonia washing tower before the washing tower. The ammonia content in the syngas entering the low-temperature methanol washing tower is around 1 ppm, and all operations are carried out in accordance with the parameters provided by the patent holder. The problem now is that the ammonia content in the lean methanol is above 70 ppm, the hydrogen sulfide content is above 320 ppm, and the water content is below 0.3%. The parameters for purified gas, exhaust gas, and acidic gas are currently normal. However, the methanol taken from the methanol-depleted tank is brownish-yellow in color, but it is clear. The current pH value of the system is around 6, and no alkali has been added to the system. There was a situation before where oil-containing wastewater entered the shift gas through some means and was carried into the low-temperature methanol wash. Wastewater may contain naphtha and certain esters; now I would like the experts here to analyze how to address the issue of poor regeneration of lean methanol. {:3_65:}{:3_65:}{:3_65:}{:3_65:}{:3_48:}{:3_48:}{:3_48:}{:3_48:}
The original poster suggests trying to replace the methanol in the system first. Could you provide more details on how the regeneration tower is operated, including the temperature, pressure, and reflux temperature? Increasing the capacity of the methanol-water separation tower can also help remove the naphtha and lipids that the poster suspects are present.
It is recommended that the poster increase the temperature and humidity control for the secondary cooling of acidic gases at the top of the thermal regeneration tower, and maintain this setting for a certain period of time; this way, ammonia can be recovered along with the acidic gases during the desulfurization process； Or, some methanol can be discharged from the system through the secondary separator. Such measures will increase the methanol loss of the system.
Increase the gas flow rate in the nitrogen stripping tower, raise the load on thermal regeneration, and increase the opening degree of the ammonia removal valve; try this first to see the effect
It is recommended to replace it with methanol; organic substances are dissolved in methanol, which can be used for analysis, and acid radicals are definitely present.
It’s still better to use methanol – it’s more direct and faster