What are the process differences between coal-based methanol and coal-based synthetic ammonia?

I know a little bit; I’m not an expert in manufacturing processes, but we expect people to have some understanding of them. Gasification, dust removal and purification, and desulfurization are the same; things change after the conversion process. The feed gas for ammonia synthesis is CO2 and NH3, whereas the feed gas for methanol synthesis is CO and H2. For detailed information, you can search on the forum, or someone who is skilled in this craft can explain it to you in detail

Firstly, gas production is different; the gas produced in ammonia synthesis is semi-water gas. Methanol gas generation produces water gas. Semi-water gas is different from water gas.

Firstly, the components of the gas produced vary, such as CO, H2, etc； The gas composition at the outlet of the transformed gas varies; for ammonia production, the lower the CO level, the better, but this is different in the case of alcohol production. Similarly, for ammonia production, the lower the CO2 level at the decarboxylation outlet, the better; this is different in the case of alcohol production. Because alcohol production requires CO + 2H2 → CH3OH and CO2 + 3H2 → CH3OH + H2O. Additionally, after decarburization in ammonia synthesis, there is a unit for refining the feed gas to reduce CO and CO2 levels to below 25 ppm. Ammonia production: N2 + 3H2 = 2NH3. The pressure required for alcohol production is relatively lower, at 5.0 MPa or 12.0 MPa, whereas ammonia production typically requires a pressure of over 20 MPa; this means that the requirements for compressors are different in such cases. I’m not sure if this is what you wanted to know.

The production of ammonia and methanol involves similar processes in terms of gas generation, gas purification, and desulfurization; the subsequent steps differ. Methanol synthesis requires CO and H2, so the CO content at the exit of the shift reactor is relatively high: CO + 2H2 = CH3OH, CO2 + 3H2 = CH3OH + H2O. In contrast, ammonia production needs N2 and H2: N2 + 3H2 = 2NH3 + Q. The CO and CO2 contents at the exit of the shift reactor are low, and methanation is carried out after that to reduce the CO and CO2 levels to 10 ppm. High levels of CO and CO2 can poison the ammonia synthesis catalyst; in severe cases, it can lead to tower-crossing accidents, cause the catalyst to age, and reduce its service life.

Thank you to everyone above; there are so many things I hadn’t thought of! So, what do you think? When setting up professional courses, should schools offer one course or two? (I teach.) It’s quite contradictory, right? One course, I guess? Can’t explain it clearly! Two courses, right? Is it too wordy? (Your comments have been very helpful to me, but my permissions only allow me to add 2 points!) :(I’m sorry, everyone!) ) This post was last edited by qinyun73 on 2009-3-20 13:09 ]

Is this contradictory? If your major is coal chemical engineering, then both coal-to-methanol and coal-to-synthetic ammonia should be included!

The gas generation process is different. In the production of ammonia, nitrogen can be added during both the upper and lower blowing stages in each gas generation cycle, in order to increase the N2 content in the feed gas; whereas in methanol production, apart from adding air during the upper blowing stage and for purification purposes, no further air is added – only steam is used for blowing, in order to avoid an excessive nitrogen content. The sulfur removal processes are essentially the same in both cases. However, in ammonia production, complete conversion takes place, while in methanol production, partial conversion of the entire gas volume or partial conversion of part of the gas volume is usual. The carbon removal processes are similar as well. The synthesis processes differ: higher pressures are required during ammonia synthesis, and the design of the synthesis towers differs significantly from that used in methanol synthesis, with substantial differences also in terms of materials used. Additionally, ammonia synthesis requires the cooling power of chillers to cool the ammonia in the mixture as much as possible, while methanol can be cooled using water alone. The methanol produced is crude alcohol, which must undergo distillation to obtain the final product, whereas ammonia can generally be sold directly after being compressed into liquid ammonia.

In the production of ammonia and methanol from coal, processes such as Shell gasification, sulfur-resistant shift reaction, low-temperature methanol washing for desulfurization and decarburization, molecular sieve liquid nitrogen washing, as well as synthetic methanol or synthetic ammonia production, differ in the following main aspects: 1. Composition of the raw gas: Ammonia production uses nitrogen to transport coal powder, while methanol production uses CO2 for this purpose; therefore, the composition of the raw gas differs； 2. Degree of CO conversion: Since the raw materials for ammonia synthesis are H2 and N2, the CO content in the process gas after conversion is required to be below 1.5%, whereas the raw materials for methanol synthesis are H2 and CO; therefore, the CO content in the process gas after conversion is required to be around 20% ； 3. Composition of the process gas after low-temperature methanol washing: A certain amount of CO2 is required in the methanol synthesis gas, typically around 3%, in order to maintain the activity of the methanol synthesis catalyst. Therefore, after low-temperature methanol washing, the CO2 content in the process gas is about 3%; whereas for ammonia synthesis, it is necessary to reduce the CO2 level to below 20PPM ； 4. The methanol synthesis unit does not have a molecular sieve and liquid nitrogen washing system; after desulfurization and decarburization via low-temperature methanol washing, the process gas is sent directly to the methanol synthesis gas compressor. In contrast, in the case of ammonia synthesis, in order to further reduce the content of inert gases such as CO/CO2/CH4 in the process gas, molecular sieve and liquid nitrogen washing systems are used before the process gas is sent to the synthesis gas compressor ； 5. A refrigeration process is required for ammonia synthesis, and a certain amount of cooling capacity is also needed in the low-temperature methanol washing process for methanol synthesis; propylene or ammonia can be used as refrigerants ； This is just my personal opinion for reference only

The raw materials used by that ammonia synthesis plant to produce synthetic ammonia are CO2 and NH3 – it’s basic common sense! ! The previous stages are basically the same; both use CO and H2 as raw materials. The only difference lies in the subsequent synthesis stage, where different catalysts result in different products and processes This post was last edited by ythzjl on 2009-3-20 17:27.]

That’s right! I also thought that everything should be included, so I created two courses: \"Methanol Production Technology\" and \"Synthetic Ammonia Production Technology\". However, during the teaching process, I found that there was too much repetition !

It’s on the 10th floor; I think the 2nd floor must be a mistake. I do have some common sense. Just make a pertinent comment – don’t be so harsh! :P

In our country, small and medium-sized nitrogen fertilizer plants often have methanol synthesis units; these were previously used for purification purposes, but now they serve as one of the main products produced. Many monol alcohol plants have been built this year as well. From a process perspective, synthetic ammonia (including methanol synthesis) and synthetic methanol often share the same gas supply system. In the case of UGI gas production, gas in which the ratio of CO to H2 exceeds 90%, as result of a rational distribution of gas flow in an upward and downward direction, is referred to as water gas; this gas is used for mono-alcohol synthesis (since N2 is an inert gas in methanol synthesis) ； Gas with 20% N2 content is called semi-water gas, which is used for ammonia synthesis. There is no difference between the two in compression systems; volume compressors are generally used ； In the transformation process, ammonia synthesis typically employs a \"medium-low-low\" or \"fully low\" transformation method, with the outlet CO level at around 3% (although it can also be below 0.1%) ； About 25% of the CO2 at the methanol shift outlet indicates incomplete conversion ； In terms of decarbonization, there are also differences between the two: methanol production generally employs the PSA method, with a few processes using NHD or MEDA; the CO2 emission level at the exit is around 4%, which indicates incomplete decarbonization. In ammonia production systems, NHD, MEDA, and low-temperature methanol washing (LTMW) are used, resulting in CO2 emissions of less than 1% at the exit ； After decarburization, synthetic methanol is generally subjected to precise desulfurization, and then it is synthesized at a pressure of 4.0 MPa ； After decarburization, the ammonia system generally also includes precise desulfurization, followed by purification. Traditional methods included hydrodesulfurization, followed by copper-alkali washing; nowadays, hydrodesulfurization is usually followed by methanation or liquid nitrogen washing, before ammonia synthesis takes place. Generally speaking, synthetic methanol and synthetic ammonia have many similarities; ammonia plants typically have both types of facilities, and the use of both methanol and ammonia is employed to maximize economic benefits!

Gas production: Nitrogen can be used in the synthesis of ammonia, but not in the synthesis of methanol. Conversion: For ammonia synthesis, it is necessary to convert carbon monoxide into hydrogen to the greatest extent possible; for methanol synthesis, it is necessary to adjust the ratio of carbon monoxide to hydrogen to suit the production of methanol. Synthesis: Both involve gas-solid phase catalytic synthesis processes, but there are significant differences between them. Additionally, methanol goes through a purification process, while ammonia does not.

This post was last edited by GreenFieldWalk on 2009-7-2 10:20. First: Methanol synthesis is the reaction of CO and H2, as well as CO2 and H2. Second: The ammonia synthesis reaction is a reaction between H2 and N2. The main components of the water gas produced by this gasification process are H2 and CO. Whether the final product is methanol or synthetic ammonia depends mainly on the design of the shift system: 1. For the production of synthetic ammonia, it is necessary that the gas resulting from the shift process have as low a CO content as possible (usually a combination of medium-shift and low-shift processes, or sometimes an entirely low-shift process); generally, a CO content of 3.5% is required. The decarburization system also needs to remove as much CO2 as possible. N2 produced in the air separation unit is added before the methanation reactor, with the hydrogen-to-nitrogen ratio being controlled at 2.8. After pressurization in the synthesis unit, the mixture is sent to the synthesis tower where synthetic ammonia is produced through reaction. The catalyst for ammonia synthesis is elemental iron. 2. Methanol production: A side line is added before entering the shift converter (our company has only one such converter); a portion of the CO does not participate in the conversion process, which ensures that the CO content at the outlet of the shift converter’s preheater is around 19.5% (on a dry basis). The COS is then hydrolyzed into H2S, and this gas proceeds to the desulfurization stage. During decarburization, 4–6% of CO2 is also retained. After thorough desulfurization, the total sulfur content is less than 0.1 ppm. At this point, the gas composition consists of approximately 27% CO, 4–6% CO2, and about 60% H2. This gas is then compressed and mixed with the recycled gas coming from the synthesis tower, before being fed back into the synthesis tower to produce methanol. Methanol catalysts are copper-based or zinc-chromium-based.