Підвищення ефективності баромембранного розділення метано-гелієвих сумішей із застосуванням каскадних схем та рециркуляції потоків

Abstract

The paper considers the current issues of deep gas purification and obtaining target components from multicomponent raw materials, which is a popular but high-cost task for various industries - from food technology to the semiconductor industry. The authors analyzed the limitations of traditional separation methods, such as sorption, desublimation, short-cycle adsorption, chemical absorption and distillation, associated with increased energy consumption, stringent requirements for fittings or phase transitions of components. The main attention in the article is paid to baromembrane separation as the simplest method that does not require thermal stabilization and is based on the difference in gas penetration rates through a porous partition under the action of a pressure drop. The mathematical model of the process is demonstrated using the example of the separation of a binary methane-helium mixture and the extraction of helium from natural gas. Methods for calculating the parameters of the output flows (permeate and nonpermeate) using iterative procedures, material balance equations and the membrane equation of state are described. It is shown that the efficiency of a single membrane is limited by a compromise between the concentration of the target product and the degree of its losses. To qualitatively improve the indicators, multi-stage compressor-free cascade schemes are considered, as well as high-efficiency schemes with the inclusion of inter-cascade compressors and the organization of flow recirculation. The positive effect of permeate flow recirculation is studied in detail, analytical dependencies for the boundary separation modes are given and the maximum recirculation coefficients are estimated for various technological parameters. The material is supplemented with graphical dependencies and technical characteristics of serial industrial membrane modules