Legaz integral enterprise of France has developed the patent technology sulfur method with EDTA as the ligand. Shell oil and Dow Chemical developed the sulferox method. The key technology of this method is the ligand. It allows the use of high concentration of complex iron solution, so it can reduce the circulation of the solution and remove the organic sulfur in the gas.
There are many studies on the process of desulfuration by complexation iron in China, such as FD method with ammonia as absorbent and sulfosalicylic acid as ligand; hedp-nta complexation iron method with HEDP and NTA as ligand; binary complexation system with triethanolamine (tea) as complexing agent and absorbent of Fe3 + and citric acid as complexing agent of Fe2 +; in addition, long Cholic acid as a ligand. Quotation of Anhui Natural Gas Desulfurization
Indirect limestone gypsum method
Desulfurization technology, analysis and characteristics
Common indirect limestone gypsum methods include sodium alkali double alkali method, alkaline aluminum sulfate method and dilute sulfuric acid absorption method.
Sodium alkali, alkaline alumina (Al2O3 · nH2O) or dilute sulfuric acid (H2SO4) absorb SO2, and the absorption liquid generated reacts with limestone to regenerate and generate gypsum. The method is simple in operation, less secondary pollution, no scaling and blocking problems, high desulfurization efficiency, but the quality of gypsum product is poor.
Lemon absorption method
Desulfurization technology, analysis and characteristics
Citric acid (h3c6h5o7 · H2O) solution has better buffer performance. When SO2 gas passes through citrate liquid, SO2 in flue gas reacts with h in water to form H2SO3 complex, and SO2 absorption rate is more than 99%.
Advantages and disadvantages:
This method is only suitable for the flue gas with low concentration of SO2, but not for the absorption of high concentration of SO2.
In addition, there are many wet flue gas desulfurization technologies, such as seawater desulfurization, ammonium phosphate compound fertilizer, liquid-phase catalysis, etc.
The complex iron desulfurization technology is a wet oxidation-reduction method for sulfide removal with iron as catalyst. It is characterized by simple process, non-toxic absorbent, and the ability to transform H2S into elemental s in the liquid phase. The removal rate of H2S can reach more than 99%. It is an environment-friendly and non-toxic desulfurization technology, which overcomes the disadvantages of the traditional desulfurization process, such as low sulfur capacity, complex desulfurization process, high generation rate of by-salt, environmental pollution, etc. the sulfur recovery rate reaches 99.99%, and the sulfur dioxide content in the flue gas after the purified tail gas incineration is reduced to 20mg / Nm3, which can meet the increasing environmental protection index.
When the sulfur output is less than 20t / D, the equipment investment and operation cost of the process have obvious advantages, and the more important advantage is that the process can achieve a very high degree of purification in the process of sulfide removal without the influence of CO2 content in the gas source. There are other significant advantages of complex iron method in the treatment of gas with low H2S content: it integrates desulfurization and sulfur recovery, absorption and regeneration can be carried out at room temperature, and the side reaction of H2S conversion to sulfur oxide is less.
There are many desulfurization and denitrification technologies and most of them are in the research or industrial demonstration stage. Among them, limestone gypsum wet desulfurization and selective catalytic reduction dry denitrification technologies are relatively mature and take the lead in commercialization. Because SO2 and NOx are acid oxides, it is feasible to remove them at the same time. Due to the advantages of small equipment investment, low operating cost and small operation difficulty, the integrated technology of desulfurization and denitrification has become a research hotspot.
The integration of desulfurization and denitrification mainly includes wet process, dry process and semi dry process. In general, the wet method has good removal effect, but the waste liquid is seriously polluted; the dry method has good removal effect, but the operation cost is high; the semi dry method has no pollution but the operation is unstable. The main wet methods are metal complex absorption method and oxidant oxidation absorption method; the dry method includes activated carbon absorption method, metal oxide catalytic absorption method and plasma method; the semi dry method is mainly absorbent jet method.
A variety of flue gas desulfurization technologies have achieved certain economic, social and environmental benefits in the process of SO2 removal, but there are still some shortcomings. With the continuous development of biotechnology and high-tech, a series of high-tech and applicable desulfurization technologies such as electron beam desulfurization technology and biological desulfurization technology will replace the traditional desulfurization methods.
In the process of fossil fuel combustion, there will be a lot of acid gases, such as sulfur dioxide, nitrogen oxides, etc., which will cause serious pollution to the atmosphere. In order to reduce the pollution of harmful gases to the atmosphere, the flue gas desulfurization technology is adopted. In the traditional flue gas desulfurization technology, including wet method, dry method, semi dry method, etc. However, after years of research, some new desulfurization and denitrification technologies have emerged, so there is the research on the integration of desulfurization, denitrification and dust removal technology.