Low-temperature methanol washing: what to do if the ammonia content is too high?
Thread Content
In low-temperature methanol washing, what are the impacts of excessive ammonia content in the ammonia scrubbing tower on subsequent operations? On which other device ports can it be output?
1. Ammonia and carbon dioxide react to produce ammonium carbonate, which tends to crystallize at temperatures below 40 degrees Celsius, thereby causing blockages in pipes, valves, and equipment. 2. Excess ammonia content leads to the formation of ammonium sulfide, which decomposes at the top of the scrubber, resulting in excessive hydrogen sulfide levels in the purified gas.
1. The best way to address excessive ammonia levels is to increase the regeneration load in the regeneration tower. 2
1. Closely monitor the ammonia concentration in the methanol in the heat regeneration reflux tank. 2. If it affects the quality parameters of the product from the scrubber tower, increase the amount of methanol discharged for replacement.
1 A high ammonia content can lead to poor regeneration in the methanol regeneration tower, and it can also result in an increase in the level of sulfides in the lean methanol stream, thereby deteriorating the quality of this lean methanol. 2 will cause the hydrogen sulfide level in the outlet gas at the top of the methanol scrubber to exceed the specified limit. 3. The gas exiting the regeneration tower, after cooling, contains high levels of ammonia; this ammonia can form carbonammonium crystals together with carbon dioxide. 4. Ammonium sulfide is likely to form, which affects the quality of the absorbent (methanol).
Solutions: 1. Increase the ammonia-removing wash water. 2. Raise the temperature of the gas exiting the regeneration tower and passing through the ammonia cooler; generally, a temperature of around 0–5 degrees is sufficient as long as it does not affect production. This helps to separate ammonia at high temperatures for discharge to the flare. 3. Increase the steam supply to the regeneration tower