The main ways to reduce sulfur dioxide emissions in power plants are: coal washing, clean coal combustion technology and flue gas desulfurization. At present, coal washing can only remove part of inorganic sulfur in coal, and there is no economical and feasible removal technology for organic sulfur in coal. Although the clean coal combustion technology has mature commercialization technology, the single machine capacity is not large; and the investment is large and the technical requirements are high, so it is difficult to popularize and use it in a large area in China in a short period of time. After nearly 30 years of development, flue gas desulfurization has become a mature and stable technology, and the type of flue gas desulfurization devices in coal-fired power plants around the world have been widely used.
Power plant desulfurization processing and production process
The desulfurization efficiency of limestone-gypsum method can be greater than 95%, which is a widely used desulfurization technology in the world.
1.Mineral processing, crushing limestone and grinding it into 200-300 mesh powder
2.The limestone powder is added with water to make a slurry as an absorbent and pumped into the absorption tower to fully contact and mix with the flue gas
3.The sulfur dioxide in the flue gas and the calcium carbonate in the slurry and the air blown from the lower part of the tower undergo oxidation reaction to form calcium sulfate. When the calcium sulfate reaches a certain saturation, it crystallizes to form dihydrate gypsum. The gypsum slurry discharged from the absorption tower is concentrated and dehydrated to make its water content less than 10%.
4.The dehydrated gypsum is sent to the storage silo by the conveyor for stacking, the flue gas after desulfurization is removed by the mist eliminator, and then heated by the heat exchanger, and then discharged into the atmosphere from the chimney.
Equipment required for desulfurization process in power plants
The medium-speed trapezoidal mill and vertical mill produced by our company are needed in the desulfurization process of the power plant.
Investment prospects
At present, many cities in my country are seriously polluted by sulfur dioxide in the air, and the coal-based energy consumption structure is an important reason for the increasingly serious sulfur dioxide pollution in my country. Coal-fired power stations are the main body of coal consumption, and the sulfur dioxide emitted by them is close to 50% of the total emission of the whole society. This feature determines that the control of sulfur dioxide emissions from coal combustion is the focus of my country’s sulfur dioxide pollution control, and the control of sulfur dioxide emissions from thermal power plants is the main breakthrough in controlling coal combustion sulfur dioxide pollution. Since 2000, the state has formulated the “Tenth Five-Year Plan for the Prevention and Control of Acid Rain and Sulphur Dioxide Pollution in the Two Controlled Areas”. On the pollution of power plants, a series of measures have been taken. Coal-fired flue gas desulfurization technology is currently a widely used desulfurization technology with ideal efficiency. For coal-fired power plants, FGD will be the main method to control SO2 emissions for a long time to come. At present, the main development trends of flue gas desulfurization technology in thermal power plants at home and abroad are: high desulfurization efficiency, large installed capacity, advanced technology level, low investment, less land occupation, low operating cost, high degree of automation, and good reliability.
The main purpose of desulfurization in power plants
Limestone – Gypsum Process (Wet Process FGD)
Technological characteristics: The limestone-gypsum method can be widely commercialized, and its absorbent is rich in resources and low in cost, and the waste residue can be recycled as commercial gypsum. Because the absorbent slurry in the absorption tower is repeatedly circulated in contact with the flue gas through the circulating pump, the utilization rate of the absorbent is high, the calcium-sulfur ratio is low, and the desulfurization efficiency can be greater than 95%.
In-furnace calcium spray tail humidification flue gas desulfurization process (LIFAC)
Process characteristics: Inject limestone powder in the appropriate temperature zone of the coal-fired boiler, and add an activation reactor after the boiler air preheater to remove SO2 in the flue gas. Its process investment is small, the floor area is small, and there is no waste water discharge, which is conducive to the renovation of old power plants.
Flue gas circulating fluidized bed desulfurization process (dry FGD)
Process characteristics: The flue gas circulating fluidized bed desulfurization process consists of absorbent preparation, absorption tower, desulfurization ash recycling, dust collector and control system. In this process, dry slaked lime powder is generally used as the absorbent, and other dry powder or slurry that has the ability to absorb and react to sulfur dioxide can also be used as the absorbent.
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