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(1) From the perspective of chemical reaction equilibrium, increasing the concentration of reactants facilitates the reaction progressing in the direction of forming products. In the desulfurization process, the concentration of acidic components in the feed gas is fixed; appropriately increasing the concentration of the solution facilitates the removal of these acidic components. For the MDEA solution, at the same gas-liquid ratio, selectivity improves as the solution concentration increases; moreover, when the gas-liquid ratio is increased correspondingly as the solution concentration rises, the improvement in selectivity is even more significant. The liquid concentration also results in a higher temperature of the rich liquid at the bottom of the absorption tower, which affects its H2S handling capacity. The concentration of the MDEA solution is generally maintained at around 40% (by mass); this unit uses an aqueous ammonia solution with a concentration of 30%. (2) Solution circulation rate: The solution circulation rate in the system is closely related to the volume of natural gas processed, the content of acidic components, as well as the properties of the amine solution itself. These four quantities can be linked together through the acid gas load of the solution. The so-called acid gas load refers to the amount of acid gas absorbed by a certain volume of solution. The gas-liquid ratio can also be used to relate them. The gas-liquid ratio refers to the volume of gas processed per unit volume of solution. In practical operation, while ensuring the quality of the purified gas, it is necessary to keep the circulation volume as low as possible in order to achieve energy savings. (3) System pressure and temperature: From the reaction equation for removing acidic components using MDEA, it can be seen that the forward reaction is an exothermic process that results in a decrease in volume. Low temperature and high pressure are required during the absorption process. The pressure is determined by various factors such as the conditions of the feed gas, the requirements of the heat exchanger tubes, and the demands of the users; it is a design parameter of the system, and generally, its value cannot be changed arbitrarily. From a selectivity perspective, reducing the absorption pressure helps improve selectivity; however, as the system pressure decreases, the partial pressures of CO2 and H2S also drop, which has an adverse effect on the mass transfer of acidic components. The acid gas load of the solution decreases, affecting the processing capacity of the plant. Therefore, when performing absorption operations, it is generally advisable to operate at the pressure specified in the design as much as possible. For solution regeneration, it isn’t the case that lower pressure is always better; there are certain requirements regarding temperature for the decomposition of amine salts, and temperature is related to pressure. In practical operation, the regeneration pressure is generally controlled at several dozen kilopascals. Regarding the temperature of the absorption tower, since the reaction between the MDEA aqueous solution and CO2 is highly sensitive to temperature, the absorption of H2S is determined by the dissolution rate of H2S. Increasing the temperature of the lean solution speeds up the rate at which the solution absorbs CO2, but it has little effect on the rate of H2S absorption. From a selectivity perspective, a lower absorption temperature is preferable. In practice, it’s not the case that the lower the temperature, the better; factors such as solution viscosity and the condensation of heavy hydrocarbons also need to be taken into account. Generally, the temperature of the lean liquid entering the tower is kept below 45°C, and slightly higher than the temperature of the feed gas. For regeneration, since the reaction heat of MDEA with H2S and CO2 is low, regeneration is relatively easy. Generally, the temperature at the top of the tower is linked to the regeneration pressure and is controlled at around 100°C. In addition to the aforementioned process requirements, three additional aspects need to be taken into account in actual operation: maintaining the cleanliness of the solution, preventing equipment corrosion, and reducing consumption levels.