Natural gas for ammonia synthesis: calculations involving natural gas, CO2, off-gases, etc. .
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I would like to ask my friends the following question; I would appreciate your guidance 1. When producing synthetic ammonia using natural gas as a raw material, how can one calculate the amount of natural gas required per ton of ammonia? Please provide an example. 2. How many tons of carbon dioxide can be produced per hour from one ton of ammonia? Please provide an example calculation: For 1 ton of ammonia, with a synthesis pressure of 13.5 MPa, how can the amount of off-gas be calculated? Please give examples
2CH4 + H2O + O2 = ------ 10H2 + 2CO2. From this equation, it can be deduced that one mole of natural gas (i.e., 22.4 L) can produce 5 moles of hydrogen, as well as 3.33 moles (i.e., 56.67 g) of ammonia. 1 ton of ammonia is equivalent to 106 g. The volume in cubic meters can be calculated by using the formula 1,000,000/56.67*22.4(L), and then dividing the result by 1000. It takes approximately 395 cubic meters of pure methane as raw material to produce 1 ton of ammonia. If natural gas contains 98.75% methane, then around 400 cubic meters of such natural gas are required. But please note that this figure refers only to the natural gas consumed as raw material; more natural gas is required as an energy source. Generally speaking, it’s quite remarkable if the gas consumption per ton of ammonia can be kept below 800. Regarding carbon dioxide, according to the above calculations, it is 1/5 of hydrogen. Methane used as an energy source is also not included. As for off-gases, these are related to gas purification, the efficiency of ammonia cooling and ammonia separation, as well as the amount of gas supplied in the cycle; there is no theoretical calculation method for them, only empirical formulas. To give an example: the amount used in the methanation process is much higher than that in the copper-ammonia process, and the amount used in the copper-ammonia process is again much higher than that in the liquid nitrogen washing or PSA processes
Thank you to everyone above for their answers. . .
However, there is a problem. The equations for the natural gas steam reforming reactions are as follows: CH4 + H2O = CO + 3H2, CO + H2O = CO2 + H2, and 2H2 + O2 = 2H2O. I think the overall reaction equation should be: CH4 + 2H2O = CO2 + 4H2. But how was it derived that the equation is 2CH4 + H2O + O2 = 10H2 + 2CO2? Could you please show me the reasoning behind this?