Discussion on coke oven gas desulfurization methods

This post was last edited by Zhou Yi on 2009-9-12 19:02 Gas Desulfurization Process 1 Advantages of TH method using ammonia as alkali source: (1) The desulfurization and decyanization efficiency is high, with the efficiency above 95%. ； (2) HCN is removed and converted into NH4SCN, which is then converted into (NH4)2SO4 through wet oxidation and then sent to the ammonium sulfate device. Therefore, the output of ammonium sulfate is higher than other processes, but it must be constructed in conjunction with the ammonium sulfate production device. ； (3) The desulfurization liquid is non-toxic, the waste liquid treatment device has a simple process and occupies a small area. ； (4) During the desulfurization process, excess elemental sulfur is not precipitated, so it is not easy to block equipment and pipelines, and the operating conditions are good. shortcoming: (1) Waste liquid treatment operates under high temperature, high pressure, and highly corrosive conditions (273°C and * * MPa), so the material requirements of the main equipment are high and manufacturing is difficult. ； (2) The liquid-to-gas ratio required for absorption and the amount of air required for regeneration are large, so the entire device consumes a lot of power. ； (3) Many side effects ； (4) Oxidants are difficult to prepare and currently need to be imported. ； (5) Small sulfur capacity (0.1g/L). To sum up, since only Baosteel has adopted this device in China, there is no mature production practice. 2 Advantages of FRC method using ammonia as alkali source: (1) The desulfurization and decyanization efficiency is high and can meet the city gas requirements at one time (H2S and HCN after the tower are reduced to 10mg/m3 and 100mg/m3 respectively) ； (2) The regeneration tower adopts high-efficiency mixing nozzles. The amount of regeneration air can be * * Therefore, the NH3-containing tail gas can be directly blended into the gas after the absorption tower, eliminating the need for regeneration tail gas treatment equipment and preventing secondary pollution of the atmosphere. ； (3) The required picric acid is cheap, easy to obtain, and consumes less ； (4) Few side reactions, fast reaction speed, and the system is closed, preventing pollution. shortcoming: (1) Picric acid is an explosive and dangerous product, which brings great difficulties to its storage. ； (2) While the waste liquid is incinerated, 25% to 30% of the NH3 in the gas will be destroyed ； (3) This method has a long process flow, occupies a large area, and is uneconomical to treat the acid production exhaust gas. If the scale of the acid production unit is too small, it is neither economical nor easy to operate. ； (4) The cost of building this process is high. Due to the above shortcomings of the FRC method, this process is only used by two coking plants including Baosteel Phase III. 3 Advantages of improved ADA process: The desulfurization and decyanization efficiency is high and can reach the city gas standard at one time (the H2S and HCN contents of the gas behind the tower can be removed to less than 20mg/m3 and 50mg/m3 respectively). shortcoming: (1) Using sodium carbonate as the alkali source consumes a lot of alkali. ； (2) The desulfurization device is located behind the crude benzene device, causing corrosion to the gas purification system equipment and pipelines. ； (3) The waste liquid treatment process is long, the operation is complex, the product grade is low, the medium is highly corrosive, the pipeline material requirements are high, and the investment is high ； (4) The exposure of the regeneration tower and the melting of sulfur cause secondary pollution to the atmosphere. ； (5) Sulfur has poor quality, low yield, and poor comprehensive benefits. ； This process has many shortcomings. 4 Advantages of Solfiban method: (1) The efficiency of desulfurization and decyanization is high. In addition to removing inorganic sulfur, it can also remove organic sulfur. ； (2) Using weakly alkaline MEA (monoethylene glycol amine) as the absorbent does not require a catalyst. The desulfurization liquid does not require oxidation and regeneration, and no by-product salts or secondary pollution will be generated. shortcoming: (1) MEA consumes a lot of steam and consumes a lot of steam, which affects economic benefits. ； (2) This process is post-desulfurization, which will cause serious corrosion to the gas purification system and pipelines. ； (3) The desulfurization requirements for urban civil gas cannot be met at one time. Due to the above-mentioned shortcomings of this process, only Baosteel Phase II adopts it in China. 5 Advantages of HPF method: (1) This process does not process waste liquid and the catalyst recovery process is short. ； (2) The process is short, investment is saved, no salt is required, and production and operation costs are low. shortcoming: (1) The first domestic development, few coking plants have applied it, and few problems have been exposed. ； (2) No regeneration, part of the desulfurization liquid is mixed into the blended coal, causing a closed loop of H2S ； (3) Catalyst consumption is large ； (4) The sulfur quality is poor, the yield is low, and the sulfur melting operating environment is poor. In view of the above shortcomings of HPF method desulfurization. 6 Disadvantages of AS method desulfurization: (1) It requires good initial cooling and electrocapturing effects to ensure that the washing system is not blocked ； (2) The condensation and sulfur recovery systems are highly corrosive. advantage: (1) Desulfurization efficiency can meet the requirements of industrial fuels and is conducive to self-use by steel plants ； (2) This process is a wet absorption desulfurization method that uses ammonia in coal gas as an alkali source. It does not require the addition of alkali, produces no waste liquid, and does not produce secondary pollution. ； (3) Pre-desulfurization can reduce corrosion of gas purification systems and pipelines ； (4) The equipment has a high degree of automation and is conducive to operation ； (5) Environmentally friendly, ammonia evaporated wastewater contains low ammonia and other impurities, sulfur and ammonia wastewater ； (6) Most domestic manufacturers use this process, the problems are fully exposed, solved well, and the technology is mature. ； (7) The sulfur produced by Claus furnace recovery has high purity (up to more than 99.8%), good quality, and high level of process automation. ； (8) No catalyst is required, catalyst regeneration equipment is omitted, and investment is reduced ； (9) Comprehensive heat exchange is fully implemented. The ingenious design of the flash chamber not only ensures that the wastewater sent reaches the standard, but also uses steam decompression to recover part of the steam, thus reducing steam by nearly 30%. Many factories now use the vacuum potassium carbonate desulfurization process, which is stable in operation. I have measured the hydrogen sulfide content in the front and back of the tower of this process for a month. The basic hydrogen sulfide content in the back of the tower is around 250mg/M3.

It is recommended to desulfurize beforehand and use ammonia method to save production costs.