Purification of semi-water gas

Methanol washing is generally used; I know that both ammonia synthesis plants I’m aware of employ methanol washing! Generally, CO2 is controlled at 10 ppm and H2S at 1 ppm.

Generally, large fertilizer plants use methanol for washing; I’ve also seen methods that employ NaOH to remove acidic gases. Nowadays, pressure swing adsorption is also used

The purification units for synthetic ammonia generally consist of shift reaction + low-temperature methanol washing + liquid nitrogen washing, or methanation~! I won’t talk about transformations and hypothyroidism~! Methanation or liquid nitrogen washing must be carried out subsequently to completely remove carbon monoxide and carbon dioxide from the process gas

The process is as follows: semi-water gas – wet desulfurization – compression – shift reaction – reforming – compression – decarburization – compression – refining – compression – ammonia synthesis

Due to current environmental requirements, copper washing has been largely phased out, with the methanol methanation process being used in most cases!

Yes, there’s also a cryogenic cleaning method, which is great too~~ It represents the direction of future development, with very little pollution…………

Current construction or ongoing technical upgrade projects involving multiple units include: 1. Converting medium-voltage and low-voltage systems to all low-voltage systems； 2. Replace solution decarburization with low-temperature methanol washing or pressure swing adsorption ； 3 Piston compressors to be replaced with centrifugal ones ； 4 The removal of trace amounts in the feed gas is carried out using the dimethyl process ；

Intermittent gas generation – Wet desulfurization (0.3 kg) – Compression (17 kg) – Medium-pressure low-CO shift reaction – Gas desulfurization – Decarburization – Compression (130 kg) – Methanol synthesis – Copper washing and refining (methanation) – Compression (314 kg) – Synthesis – Liquid ammonia storage tank – Urea

Old plants often use copper washing to refine and remove trace amounts of CO and CO2 from the remaining feed gas. New plants mostly employ the alcohol-etherification process. Compared to methanation, this process does not increase the content of inert gases in the syngas, allowing for a significant reduction in the amount of syngas that needs to be vented.

Semi-water gas (3–5 KPa) – Primary desulfurization – Compression (2.2 MPa) – Shift reaction (2 MPa) – Secondary desulfurization (1.9 MPa) – Decarburization (1.8 MPa) – Compression (12.6 MPa) – Dimethyl – Compression (23 MPa) – Ammonia synthesis

1. Desulfurization of semi-water gas: Removal of organic sulfur and inorganic sulfur. (1) Wet desulfurization——① Chemical absorption methods (neutralization method, wet oxidation method); ② Physical absorption methods; ③ Physicochemical absorption methods. (2) Dry desulfurization——Removal of small amounts of hydrogen sulfide and organic sulfides from semi-water gas; this method includes the zinc oxide method, cobalt-molybdenum hydrogenation method, activated carbon method, molecular sieve method, and iron hydroxide method. 2. Transformation of carbon monoxide: CO + H2O → H2 + CO2 + Q, which removes carbon monoxide while producing hydrogen. (1) Medium-temperature shift, 2–4% CO2 remaining; (2) Low-temperature shift, 0.5% CO2 remaining; 3. Decarbonization: Removal of carbon dioxide from semi-water gas. ① Chemical absorption methods——ammonia water method, hot potassium alkali method, ethanolamine method. ② Physical absorption methods——water washing method, low-temperature methanol washing method, propylene carbonate method. ③ Physicochemical absorption method——sulfolane method. 4. Removal of small amounts of carbon monoxide and carbon dioxide: After removal, CO + CO2 ≤ 10 ppm. (1) Physical methods – liquid nitrogen washing. (2) Chemical methods – copper washing, methanation, pressure swing adsorption. Last edited by hjm88880 on 2009-3-30 16:20.]

Semi-water gas – primary wet desulfurization – medium/low/very low shift – decarburization – activated carbon desulfurization – normal temperature water desulfurization – advanced desulfurization – dimethyl – ammonia synthesis； The copper washing process is now hardly used due to its high consumption and significant pollution; it is more often replaced by the dimethyl process.