An acid gas treatment system and treatment method based on ammonia desulfurization

Abstract

The invention provides an acid gas treatment system based on ammonia-process desulfurization. The acid gas treatment system comprises an acid gas burning unit, a burnt tail gas oxidation unit, a quenching unit, an ammonium sulfate preparation unit, a cooling dehydration unit and a tail gas demisting unit which are connected in sequence. The invention further provides an acid gas treatment method based on the ammonia-process desulfurization. The acid gas treatment system and the acid gas treatment method have the advantages that the desulfurization efficiency is high; the concentration of SO2 (Sulfur Dioxide) in emitted tail gas is lower than 200 mg / m<3>; the recovery rate of sulfur can reach 99.5 percent above; the desulfurization process is free from ammonia escape and excessive wastewater discharge; heat can be effectively released through reaction; the requirements for environmental protection are better met; the requirements for equipment materials of the treatment system are low; the treatment system is unlikely to damage in the using process, long in service life, low in investment, small in occupied area, low in operation cost, and safe and reliable to operate.

Description

technical field [0001] The invention relates to the field of acid gas treatment, in particular to an acid gas treatment system and treatment method based on ammonia desulfurization. Background technique [0002] In petrochemical, coal chemical and other production processes, the sulfur in the raw materials is finally converted into acid gas containing hydrogen sulfide during the processing process. Hydrogen sulfide is a very harmful substance to safety and the environment. It must be treated or Recycle. [0003] For some plants with by-product liquid ammonia or ammonia water, such as coal low-temperature low-pressure gasification to natural gas plant, due to consideration of the sale and outlet of liquid ammonia or ammonia water, ammonia desulfurization process can be used to remove all or part of the acid gas The sulfur is converted to ammonium sulfate. Usually, for a small-scale sulfur recovery system with an annual capacity of less than several thousand tons, all the ac...

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Problems solved by technology

[0013] (1) Conventional ammonia desulfurization process for SO 2 The absorption efficiency is low, generally only about 90-95%, due to the SO in the power plant or boiler flue gas 2 The concentration is low, generally only several hundred to several thousand mg / m3, so the SO in the tail gas after desulfurization 2 Able to meet emission standards, but the sulfur concentration in acid gas or Claus tail gas is high, usually SO after incineration 2 Concentration reaches 2~3%, so high SO 2 The concentration cannot meet the emission standard by the conventional ammonia desulfurization process

[0014] (2) In the conventional ammonia desulfurization process, it is necessary to blow air into the tower bottom tank at the bottom of the absorption tower to oxidize the ammonium sulfite in the solution into ammonium sulfate. The conversion rate into ammonium sulfate is low, usually only about 90%, which leads to the impurity of ammonium sulfate product, and due to the instability of ammonium sulfite, it causes partial decomposition during the crystallization of ammonium sulfate and product storage and transportation, and releases SO 2 gas

[0015] (3) SO 2 The absorption and reaction with ammonia is a reversible equilibrium reaction, both leading to SO 2 The absorption efficiency is low, which may also lead to the escape of ammonia

[0017] In addition, when using the ammonia desulfurization process to treat the Claus tail gas, due to the high water content in the Claus tail gas, too much water cannot be added to the system, otherwise it will affect the concentration of the ammonium sulfate solution discharged as the product, increasing the Energy Consumption and Investment of Ammonium Sulfate Crystallization System

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