Introduction to several common sulfur recovery methods (reprinted)

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This post was last edited by liaifeng on 2018-8-18 10:13 The current sulfur recovery methods mainly include wet and dry desulfurization, and the dry method is divided into: Traditional Claus process, sub-dew point Claus process, reduction absorption process, direct oxidation Claus process, oxygen-enriched Claus process, and oxidation absorption Claus process ； The wet methods mainly include Lurgi's low and high temperature condensation process and Topsoe's WSA process. 1 Dry desulfurization 1.1 Conventional Claus method The Claus method is a relatively mature multi-unit treatment technology and is currently the most widely used sulfur recovery process. Its process is: Acidic gas containing hydrogen sulfide is burned in a Claus furnace to oxidize part of the hydrogen sulfide into sulfur dioxide, which then reacts with the remaining unreacted hydrogen sulfide on the catalyst to generate sulfur. The characteristics of the traditional Claus method are: 1) Control n(O2): n(H2S)=1: 2. If the oxygen content is too high, SO2 will overflow; if it is too low, the H2S removal efficiency will be reduced. ； 2) It is necessary to install a mist eliminator to remove sulfur from the gas flow to increase sulfur recovery. ； 3) The total sulfur recovery rate of Claus method is 94%-96% ； 4) The Claus method should not be used for gases containing flammable components such as coal gas, or when the sulfur mass fraction is less than 40%. 1.2 Sub-dew point Claus process The so-called sub-dew point process is a process whose main feature is the Claus reaction at a temperature lower than the sulfur dew point. Mainly include Sulfreen, Hydrosulfreen, Carbonsulfreen, Oxysulfreen, CBA, ULTRA, MCRC, Clauspol 1500, Clauspol 300, Clisulf SDP, ER Claus, Ma * sulf and other processes. 1.3 Reduction and absorption process The reduction and absorption process converts organic sulfur and SO2 into H2S for absorption, so the total sulfur recovery rate can reach more than 99.5%. Mainly include SCOT, Super-SCOT, LS-SCOT, BSR/Amine, BSR/Wet O * dation, Resulf, AGE/Dual Solve, HCR, Parsons/BOC Recycle, Sulfcycle and ELSE processes. 1.4 Direct oxidation process Direct oxidation refers to the direct oxidation of H2S to sulfur on a solid catalyst. It is actually a new development of the Claus prototype process. The key to the direct oxidation process technology is to develop a highly active catalyst with good selectivity and insensitivity to H2O and excess O2. It is currently prepared with different mixtures of iron-based metal oxides. Selective catalytic oxidation sulfur recovery technology mainly includes: There are mainly processes such as Seleclox, BSR/Selectox, BSR/Hi-Activity clause, MODOP, Superclaus, Catasulf and Clinsulf DO. Take the Superclaus process as an example for a brief introduction. There are 2 types of Super Claus Craft: Super Claus-99 type and Super Claus-99.5 type. The gas does not need to be dehydrated in the Super Claus process. During selective oxidation, excess oxygen can be added without significant impact on selectivity. The process method is simple and easy to operate. The process is continuous without periodic switching, the sulfur recovery rate is high, investment is saved, energy consumption and raw material costs are low, and the application scale is not limited and the scope of use is wide. 1.5 The oxygen-enriched Claus process uses oxygen-enriched air or even pure oxygen instead of air in the Claus device, which can correspondingly reduce the amount of inert component N2, thereby improving the processing capacity of the device. The industrialized oxygen-enriched Claus processes include COPE, SuRe and Oxyclaus ； In order to solve the problem of operating costs, PS Claus, which uses pressure swing adsorption to supply oxygen, emerged. ； In order to solve the furnace temperature problem, the NOTICE process was produced. 1.6 Oxidation and absorption process This type of process oxidizes the sulfur in the tail gas into SO2, and then reuses it after absorption and desorption. It is rarely used in the Claus process. Such processes mainly include Wellmawn-Lord, Elsorb and Cominco de Sox processes. 2 Wet desulfurization 2.1 Low-temperature condensation process The low-temperature condensation process is a wet contact acid-making process proposed by the German Lurgi Company in the 1930s. In this process, the sulfuric acid condensation device is a spray packed tower, followed by a demister. The process is: 1) Clean gas containing hydrogen sulfide is burned in the incinerator ； 2) Sulfur dioxide is catalytically converted in the converter ； 3) The gas exiting the converter directly enters the condensation tower, countercurrently contacts the circulating cold sulfuric acid sprayed at the top of the tower, and condenses into acid. In the low-temperature condensation process, the SO2 conversion rate can reach 98.5%, and the product ω (H2SO4) is about 78%. The disadvantage is that the scope of use is limited and it cannot handle gas with a post-combustion φ(SO2) lower than 3%, so it is only suitable for small-scale devices. 2.2 Concat method (high-temperature condensation process) Concat process, also known as high-temperature condensation process, is an improved wet contact catalytic production of sulfuric acid process launched by Lurgi Company after low-temperature condensation process. High temperature condensation means that sulfur trioxide gas and water vapor condense into acid at high temperature. The condensation device of this process uses a Venturi condenser. The process is: 1) Wet H2S gas is combined with fuel gas and burned in the incinerator ； 2) SO2 is oxidized in the converter ； 3) The gas enters the condensation venturi tube and contacts the highly dispersed hot sulfuric acid in parallel flow to generate sulfuric acid, which precipitates and releases heat. Finally, the gas is cooled and the sulfuric acid droplets are separated. This process is particularly suitable for treating gases with high temperature and low H2S, CS2 and CO2 content, and can handle φ(SO2) in combustion gases.