METHODS FOR CLEANING AND ENRICHING THE GAS OBTAINED IN A BIOGAS PLANT
The article has considered the issue of how to purify methane, derived from biogas, from harmful impurities. It has been known that today there are three main ways of cleaning biogas: the method of liquid (wet) and solid (dry) chemical absorption of impurities (absorption and adsorption), the method of membrane separation and freezing (cryogenic method). The removal of moisture from biogas is accomplished mechanically, and also due to a decrease in temperature. A small amount of hydrogen sulphide is removed by physical or chemical means. An effective absorber of hydrogen sulphide is activated carbon. It has been found out that for today the most economical method, allowing cleaning biogas from hydrogen sulphide, was dry cleaning. It has been determined that there is another combined method (membraneabsorption) of biogas separation, which allows to avoid additional energy costs for heating the chemical sorbent and cooling the gas mixture - with the cryogenic method of cleaning, or for increasing the biogas pressure - with the membrane cleaning method. It has been also established that after the process of processing biogas it is possible to utilize waste from a biogas plant. It has been concluded that the membraneabsorption method of separation and purification of biogas is the most rational for today; the profitability of gas cleaning to the quality of natural gas justifies itself only with a high fuel consumption; the bulk of income by processing companies of this level does not arise from the processing of biogas or its compression, but from the production of biological fertilizers.