Separacja siarkowodoru z gazu ziemnego w kaskadowych układach technologii membranowej

Under the new economic conditions, the exploitation of sour gas deposits reduces profits when using the conventional processes used to prepare gas for transport. Adding an inexpensive membrane unit as a preliminary technology before the classic quite energyconsuming amine absorption process (hybridization) can significantly reduce the cost of removing acidic components from natural gas. The article is a continuation of the author’s previous publications related to the research on the separation of several CH4–H2S mixtures. Gaseous separation tests were carried out on modules with polyimide membranes in a wide range of pressures. The scope of the conducted separation tests was extended to concentrations of 22% H2S in the gas mixture. Based on the experimental results, data for simulations and forecasts necessary for the evaluation and comparison of two-module cascade systems were obtained. The influence of the pressure of the gas flowing through the membrane (permeate) on the separation effects was determined. Increasing the pressure of the permeate flux reduces the concentration of hydrogen sulphide in it and increases the loss of methane. It was found that the ratio of the inlet gas pressure to the permeate pressure is of greater importance than the pressure difference. Single-stage membrane systems are sufficient for gas containing more than 12% H2S, for less sulfurized gases a two-stage cascade system is suggested. In the case of low concentrations of H2S in the gas, the methane losses in the one-stage system are too high. The article compares two variants of two-module cascade membrane systems. The paper presents comparative results of hydrogen sulphide content in simulation calculations for inlet gas with a concentration of 7.73% for both systems with a compressor before and after the second separation stage. The calculations showed that for the variant with the compressor before the second modulus, the H2S concentrations in the product streams are more favourable. H2S removal rates from the inlet gas were calculated for both systems. The influence of the permeate composition on the phase phenomena related to their condensation and compression for injection into the bed together with the acid gas from the amine part of the hybrid installation was considered.