Why is ammonia present in gas purification?
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As the title says. Where is it from? Could that big shot explain it?
In gasification, due to the use of nitrogen and the production of hydrogen during gasification, ammonia may be formed under high pressure and high temperature conditions
As mentioned above, the conditions for ammonia formation. Of course, the presence of nitrogen and hydrogen in the raw materials is the main factor.
Primarily, under high temperature and pressure conditions, the nitrogen and hydrogen components derived from coal react to form ammonia.
Ammonia is presumably formed when a very small amount of nitrogen and hydrogen react at high temperatures to produce ammonia gas
I’m not sure about the manufacturing process. It’s possible to carry out a high-temperature reaction between hydrogen and nitrogen in small quantities, but the amount produced will definitely not be large. If we consider what is mentioned in the question, we need to take into account the issues related to the circulating water in the gas generation section, steam, and the processes involved in the incinerator. If it’s not for takeout, there won’t be much ammonia. It’s very simple: the reaction for ammonia synthesis is difficult to carry out without the use of a catalyst
Under high temperature and pressure, in a reducing environment with the presence of carbon, some of the nitrogen is reduced to ammonia compounds
The nitrogen content in coal is generally 0.5%-2%, and it is released mainly in the form of nitrogen gas when coal is burned. During carbonization (coke production), it is released into the gas in the form of nitrogen, ammonia, and HCN. This is the source. Additionally, cooling the gas in a horizontal pipe with ammonia after it is produced also causes some ammonia to enter the gas. This is an indirect source. From these two aspects, the sources of ammonia in gas purification.
During the high-temperature coking process, the amino groups of some of the organic compounds in the coking coal undergo cleavage to form nitrides, resulting in the production of ammonia. The ammonia content in the gas depends on the nitrogen content in the coal as well as the conditions of the coking process. The highest yield of ammonia is achieved when the coking temperature is between 850 and 900 degrees; if the temperature is increased, ammonia reacts with coke to produce HCN. In the coking process, 50% of the nitrogen forms stable compounds that remain in the coke; 3–4% of the nitrogen turns into indole, quinoline, pyridine, etc.; 10–12% becomes nitrogen gas; and 16–23% results in ammonia. The yield of ammonia from the coal used as feedstock is 0.2–0.4%
In the gasifier, nitrogen and hydrogen in carbon combine to form a small amount of ammonia at high temperatures. The ammonia in the purification system is obtained by vaporizing gas and then separating it through purification and cooling.
Mainly, coal contains nitrogen, and nitrogen reacts with hydrogen to produce ammonia! If dry coal powder is transported using nitrogen, the ammonia content will be even higher!
Is ammonia present in gas purification? Was there an ammonia leak during your purification process? Or it was cooled with liquid ammonia during the solution circulation. Leaks can occur in all cases.
It is related to the gasification process; the temperatures mentioned above for the gas phase are generally not high, around 850–900 degrees Celsius. In the Shell or GE processes, it is almost impossible for ammonia to be produced from coal. (In the Shell process, the core temperature of gasification reaches around 3000 degrees Celsius, at which point any ammonia present would be decomposed.) I’m not sure whether the purified gas referred to by the original poster is obtained after acid treatment; if so, then another possibility exists, namely that it originates from the shift reaction. Nowadays, the full low-temperature shift process is commonly used, and some domestic manufacturers add a certain amount of ammonia to the catalysts used in this process
Indeed, some ammonia is produced in the reaction; iron-based catalysts are used in ammonia synthesis, while cobalt-molybdenum catalysts are commonly used in shift reactions. It belongs to the same group as iron and also has the ability to catalyze the synthesis of ammonia.
In the gasifier and converter, the reactions all take place at high temperatures. The surface of the transformation catalyst is suitable for the ammonia synthesis reaction; only a small amount is produced. When the concentration of NH3 reaches a certain level, a decrease in temperature allows it to easily form NH4HCO3 crystals together with H2O(vapor) and CO2
Firstly, ammonia is inevitably produced during gas generation, and it is also used in the cooling process
You use coke oven gas to synthesize methanol in your dreams, right? I’m not very familiar with the gasification process; as far as I know, ammonia water is not used for cooling.
What’s the low transformation temperature anyway? Around 440, I guess! The design parameters of our plant remain unchanged before and after the converter. But what about vaporization? It seems that in our plant the temperature is over 1,000 degrees, and ammonia is mainly obtained through vaporization.
First of all, nitrogen can come from both the coal itself and the air, while hydrogen is a common component in the gasified gas； Under high temperature and pressure, the two react to produce ammonia! The amount of ammonia should not be large! !
Back to the 17th floor – ammonia should be useful for absorbing CO2 to produce ammonium bicarbonate!
Let me add a few words as well: 1. A small amount of ammonia is produced during the gasification process (especially high-pressure gasification) as well as during the shift process. 2. The ammonia generated in the gasification stage is generally removed through washing. 3. If a saturated tower process is used in the shift stage without employing liquid ammonia evaporation, ammonia levels can rise to unacceptable levels. 4. The nitrogen content in the crude syngas produced in the gasification stage has a significant impact on ammonia levels