Several issues with ammonium carbonate crystals and their solutions?
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This post was last edited by Yun Qianli on 2015-11-17 at 10:04. In the gas phase of the methanol regeneration tower, acidic gases passing through the cooling heat exchangers tend to form crystals; these are generally considered to be ammonium carbonate, that is, ammonium bicarbonate or ammonium carbonate~~(1) Is it possible that it could be ammonium sulfide? ? (2) At what temperature below does ammonium carbonate tend to crystallize? (3) At what temperature does the crystal tend to decompose during rewarming? (4) What are the main methods to prevent ammonium carbonate crystallization? :)
1. You can search on Baidu; ammonium sulfide generally exists in solution form. Anhydrous sulfuric acid is a crystalline substance. It is generally believed to be ammonium carbonate, as it is easy to form and also easy to decompose. There should be a small amount of sulfuric acid an. During the maintenance, we also removed some crystals; the center of these crystals was light yellow while the periphery was green. It has a strongly pungent odor. 2.40~30 degrees Celsius, these are the inlet and outlet temperatures on the shell side of the acidic gas heat exchanger. 3. The issue is not about maintaining a certain temperature to prevent crystallization; rather, due to the characteristics of the process, there is a high concentration of hydrogen sulfide, carbon dioxide, as well as ammonia in this area of the system. It crystallizes easily at this temperature. So this device is prone to clogging. 4. During rewarming, use a bypass route, disable the cryocooler, and allow the temperature to rise naturally. Temperature of the acidic gas outlet water cooler. 5. It is essential to strictly control the ammonia entering the system. The main task is to operate the ammonia scrubber properly. Ensure an adequate water supply.
Yes, dealing with this issue takes a long time; there’s a high amount of alcohol in the rewarmed mixture, and it repeats over and over again – with no particularly effective way to reduce crystallization yet. Controlling the temperature of the ammonia washing tower and the incoming process gas can only reduce the source of crystals; over time, crystals will still accumulate~
Have you ever tried raising the temperature of the water cooler a bit?
Accumulation is normal; strictly control the process parameters. If the ammonia scrubber does not seem to be effective, consider replacing it with high-efficiency trays. As for the water volume, it’s sufficient to ensure that there is liquid on each tray. We have basically not adjusted this temperature, because no matter how it is adjusted, this gas still has to go through temperature changes of 40-30-(-20)-30; it either accumulates here or there. We stopped using the cryocooler for rewarming; the bypass was never activated. A class can return to normal in 12 hours.
What is the temperature required for rewarming? After rewarming, should the acidic gases be vented directly through a flare or sent to sulfur recovery? In the case of desulfurization and recovery, how is catalyst carbon deposition controlled?