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Common processes for biogas desulfurization and dehydration: As policies aimed at energy conservation and emission reduction gain more acceptance, many companies intend to use the biogas produced in wastewater treatment plants as a substitute for natural gas for use in boilers or for power generation. Therefore, the hydrogen sulfide removal process (desulfurization) prior to biogas utilization becomes a difficult decision for factories and plant managers. Currently, the commonly used processes include dry desulfurization, wet desulfurization, and biological desulfurization by Tangshan Lvyuan. This article will provide a brief explanation and comparison of these three processes for you. I. Common desulfurization processes 1. Dry desulfurization Comparison of the three processes: dry, wet, and biological desulfurization. Biogas enters the desulfurization tower from one end, is purified through a filler layer (whose main components are activated carbon and iron oxide), and then exits from the other end. Hydrogen sulfide reacts with the iron oxide in the filler layer to form iron sulfide; once the reaction with the iron oxide is complete, it can be regenerated. Principle of desulfurization: http://5b0988e595225.cdn.sohucs.com/images/20171208/c18c2bae96b244589c1787172b191c52.jpeg Fe2O3·H2O + 3H2S = Fe2S3 + 4H2O. Principle of regeneration: Fe2S3 + 3/2 O2 + 3H2O = Fe2O3·H2O + 2H2O + 3S. Wet desulfurization involves feeding biogas into a scrubber, where it is washed and absorbed by an alkaline solution; the resulting wash liquid then enters a rich liquid tank and a regeneration tank. Through chemical treatment methods that involve catalysis and oxidation, the sulfides are converted into elemental sulfur (sulfur bubbles), and the absorbent liquid can be regenerated and reused. 3. Biological desulfurization: Biological desulfurization is also a type of wet desulfurization. Compared with the catalytic oxidation process used in wet desulfurization, its main difference lies in the use of sulfur bacteria instead of chemical catalysts to directly oxidize sulfides into elemental sulfur. Reaction principle: H2S + OH- → HS- + H2O; HS- + 1/2O2 → SO4^2- + OH-. Note: 1) Dry desulfurization is mostly used in situations where the hydrogen sulfide treatment load is low, or when very high desulfurization efficiency is required. At this time, dry desulfurization is mostly used for further desulfurization after wet desulfurization or biological desulfurization. http://5b0988e595225.cdn.sohucs.com/images/20171208/ba602963888140d384868bcaba943032.jpeg2) When determining the desulfurization efficiency, it is recommended to establish a reasonable level of removal based on the limits imposed by subsequent equipment (boilers or generators) on hydrogen sulfide concentrations, as well as the ratio of biogas to natural gas consumption. We generally recommend keeping the final hydrogen sulfide content between 25 and 100 ppm. Methods for dehydrating biogas: The biogas coming out of the fermentation unit contains saturated water vapor, which can be removed using 3 methods. (1) Cold separation method. The cold separation method is a technique that utilizes changes in pressure energy to cause temperature changes, thereby condensing water vapor from the gas phase. There are two commonly used processes: A. Throttling expansion cold dehydration method. It is generally used for high-pressure gas, where throttling expansion or cryogenic separation is employed to cause part of the water to condense. B. Cooling after pressurization. Such as the cooling and dehydration of the purified gas at a pressure of 0.8 MPa. (2) Solvent absorption method. Examples of such dehydrating solvents include calcium chloride, lithium chloride, and glycols. (3) Solid physics water absorption method. Adsorption occurs as a result of forces acting on the surface of solids. Depending on the nature of these surface forces, it can be divided into chemical adsorption (which cannot be reversed after dehydration) and physical adsorption (which can be reversed after dehydration). A biogas desulfurization and dehydration system is an essential device in biogas production; such systems remove harmful gases from biogas. Tangshan Lvyuan ensures that biogas is produced effectively and safely throughout this process.