① Types and contents of acid gas components in feed gas;
② Quality requirements of purified gas;
③ sour gas demand;
④ Temperature and pressure of acid gas and conveying temperature and pressure of purified gas;
⑤ Treatment capacity of feed gas and hydrocarbon content in feed gas;
⑥ Selectivity required for removing acid gas;
⑦ Quality requirements of liquid products (such as NGL);
Investment, operation and technology patent fees;
Pet-name ruby treatment of harmful by-products.
2. Selection principle According to the industrial practice at home and abroad, the following principles can be referred to when selecting various alcoholamine methods and sulfonamide methods for desulfurization and decarbonization.
(1) In general, for a desulfurization and decarbonization unit with large capacity, the possibility of adopting the alcohol amine method should be considered first, namely:
① When the carbon and sulfur content in the feed gas is relatively high (the molar ratio of CO2/H2S is greater than 6), the selective MDEA method should be adopted to obtain the acid gas suitable for the conventional Claus sulfur recovery unit (when the concentration of H2S in the acid gas is lower than 15%, it cannot enter the unit) and other occasions where H2S can be selectively removed;
(2) When the carbon and sulfur in the feed gas are relatively high and a considerable amount of CO2 needs to be removed, the mixed alkanolamine method composed of MDEA and other alkanolamines (such as DEA) or the appropriate formula solution method can be selected;
③ When the content of H2S in feed gas is low and the content of CO2 is high, and deep decarbonization is needed, appropriate MDEA formula solution (including active MDEA method) can be selected;
④ When the feed gas pressure is low, the quality index of purified gas H2S is strict, and CO2 needs to be removed, MEA method, DEA method, DGA method or mixed alcohol amine method can be selected; If the quality indexes of H2S and CO2 in purified gas are strict, MEA method, DEA method or DGA method can be adopted.
⑤ DGA method can be used in cold or desert areas with water shortage.
(2) Need to remove organic sulfides When it is necessary to remove organic sulfides from feed gas, sulfonamide method should generally be adopted, namely:
① Sulfinol-D method (sulfonamide ⅱ method) should be adopted when H2S and a certain amount of organic sulfur in feed gas need to be removed and CO2 needs to be removed at the same time;
② The feed gas contains H2S, organic sulfur and CO2. Sulfinol-M method (sulfonamide ⅲ method) should be adopted when it is necessary to selectively remove H2S and organic sulfur and retain a certain amount of CO2.
(3) When treating feed gas with high H2S partial pressure, the energy consumption of sulfonamide method is much lower than that of ethanolamine method;
(4) If the content of organic sulfur in the feed gas can't reach the quality index after being treated by sulfonamide method, molecular sieve method can be used to remove organic sulfur.
(3) Feed gas with low H2S content When the H2S content in the feed gas is low, the potential sulfur content (t/d) based on the treatment capacity of the feed gas is not large, and the carbon and sulfur are relatively high, and CO2 removal is unnecessary, the following methods can be considered, namely:
① When the potential sulfur content is between 0.5 and 5t/d, direct conversion methods can be considered, such as ADA-NaV03 method, complex iron method and PDS method;
(2) When the potential sulfur content is less than 0.4t/d (no more than 0.5t/d at most), recovery methods such as solid iron oxide method and iron oxide slurry method can be selected.
(4) The feed gas with high pressure and high acid gas content may need to use other methods or a combination of several methods besides ethanolamine method and sulfonamide method. Namely:
① When CO2 is mainly removed, membrane separation method, physical solvent method or active MDEA method can be considered;
(2) When a large amount of H2S and CO2 need to be removed at the same time, the acidic gas rich in H2S can be obtained by the selective alkanolamine method, and then the mixed alkanolamine method or the conventional alkanolamine method can be selected to achieve the quality index or requirement of the purified gas;
③ When a large amount of CO2 and a small amount of H2S in the feed gas need to be removed, the membrane separation method can be selected first, and then the ethanolamine method can be selected to meet the treatment requirements. The above are just the general principles for selecting the desulfurization and decarbonization methods for synthetic ammonia. In practice, a scheme should be determined after technical and economic comparison of several schemes according to specific conditions.