Recycled flue gas desulfurization and denitration method

Abstract

The invention relates to a recycled flue gas desulfurization and denitration method, which sequentially comprises the following steps of: introducing flue gas of SO2 and NOx into a desulfurizing tower, and absorbing the SO2 with a desulfurizing agent (barren liquor) in the desulfurizing tower; desorbing the desulfurizing agent (rich liquor) which absorbs the SO2 through a multi-effect evaporator,releasing the SO2 gas, and concentrating the SO2 gas into liquid SO2 through condensation drying; making the desulfurized flue gas enter a denitration tower, injecting gaseous ozone from an ozone generator, oxidizing the NO in the flue gas, absorbing the oxidized NO by using a denitrifier to form nitrate; crystallizing and separating out the nitrate in the solution after the nitrate reaches certain concentration, and filtering and drying to obtain the nitrate product. The method turns the wastes into wealth, and the SO2 and NOx in the flue gas are recycled by higher-additional value liquid SO2 and nitrate products, so that the recycling and value maximization in the desulfurization and denitration process is realized. Due to the adoption of the technical scheme, the high desulfurization and denitration rate can be achieved, the desulfurization rate is over 96 percent, the denitration rate is more than 90 percent, and the purity of the nitrate product is over 96 percent. The method hasthe advantages of simple desulfurization and denitration process, low investment, and low operation cost for desulfurization and denitration, and solves the problems that the conventional desulfurization and denitration process has high cost, generates a side product of a mixture of sulfuric acid (sulfate) and nitric acid (nitrate), and has low additional value.

Description

technical field [0001] The present invention relates to a resource-based flue gas desulfurization and denitrification method, in particular to NO and SO in flue gas 2 The method of removing and realizing resource recovery respectively. Background technique [0002] my country is a big coal-burning country, and coal accounts for 75% of the total primary energy consumption. The massive consumption of energy has caused serious air pollution, the most prominent of which is SO 2 and NO x Acid rain hazards from emissions, and NO x Ozone layer depletion and photochemical smog. According to the "First National Pollution Source Survey Bulletin" published by the Ministry of Environmental Protection on February 6, 2010, in 2007, my country's sulfur dioxide emissions were 23.20 million tons, smoke and dust 11.6664 million tons, and nitrogen oxides 17.977 million tons. The task is daunting. At present, my country's total sulfur dioxide emissions rank first in the world, and the econ...

AI Technical Summary

Problems solved by technology

[0003] At present, desulfurization and denitrification are placed in the same important position in our country. The existing mainstream technology has many advantages and can meet the requirements of environmental protection, but the disadvantages are high investment and operation costs, desulfurization by-products such as calcium sulfate, etc. The value is low, and it even brings secondary pollution problems, and denitrification is a worthless by-product N 2 , but consumes a large amount of reducing agent ammonia and expensive catalyst

[0012] my country is a sulfur-deficient country, and it needs to import a large amount of sulfur from abroad every year to prepare SO 2 or sulfuric acid, which in turn is a SO 2 Most of the existing desulfurization technologies in countries with large emission 2 It is absorbed to form solid waste gypsum, and a small amount of desulfurization technology produces ammonium sulfate with low fertilizer efficiency

At the same time, in the desulfurization and denitrification process, most of the SO in the flue gas 2 Absorbed with NOx to form a mixture of sulfate and nitrate, it is difficult to form high value-added resource products

[0013] To sum up, there are still deficiencies in the existing desulfurization and denitrification process, and the desulfurization and denitrification technology needs to be further improved

Images