发布时间：2022-07-25 14:49:11 人气：105 点赞：0
In order to reduce air pollution, thermal power plants should strictly control SO2 and other emissions. Therefore, a desulfurization unit is required. Due to the high resistance of desulfurization unit, besides overcoming the resistance of flue gas system with induced fan, it is also necessary to install a desulfurization booster fan to overcome the resistance of desulfurization unit. Therefore, the desulfurization and oxidation fan of thermal power plant must have the function of forcing gas transmission! Roots blower is one of the most popular industrial fan equipments, which has a high cost-effective and can meet the demand. Therefore, many thermal power plants will find Roots blower in the process of oxidation desulfurization! Next, let us know the function and position of Roots blower in desulfurization and oxidation together!
Function of desulfurization and oxidation fan in thermal power plant: SO2 in flue gas is absorbed by slurry and reacts with limestone to form unstable calcium sulfite (or calcium bisulfite). The sulfite is oxidized to sulfate with participation of oxygen. Oxygen comes from blower of oxidation fan. Most of the oxidation fans squeeze each other through two or three rotors, sucking air in and squeezing it out.
Principle of desulfurization and oxidation fan in thermal power plant: limestone powder is added with water to make slurry as absorbent, and then pumped into absorption tower to make full contact with flue gas. Sulfur dioxide in flue gas reacts with calcium carbonate in slurry and air from lower part of tower to form calcium sulfate. Calcium sulfate crystallizes to form gypsum dihydrate after reaching certain saturation. The gypsum slurry discharged from the absorption tower is concentrated and dewatered so that its water content is less than 10%. Then it is sent to the gypsum storage bin for stacking with a conveyor. After desulfurization, the flue gas is removed by the demister and heated by the heat exchanger to raise temperature. Then it is discharged into the atmosphere by the chimney. As the absorbent slurry in the absorber tower contacts the flue gas repeatedly through the circulating pump, the utilization ratio of absorbent is very high, the calcium and sulfur ratio is relatively low, and the desulfurization efficiency can be more than 90%.
In order to reduce air pollution, thermal power plants should strictly control SO2 and NOx emissions. Therefore, a desulfurization unit is required. Due to the high resistance of desulfurization unit, besides overcoming the resistance of flue gas system with induced fan, it is also necessary to install a desulfurization booster fan to overcome the resistance of desulfurization unit. The supercharged fan is arranged in various ways in the desulfurization unit. At present, relatively independent arrangement of boiler flue-air system is adopted.
In the desulphurization system of power plant, there are induced draft fan and desulphurization booster fan, of which the desulphurization and oxygen booster fan is Roots blower.
As shown in the diagram, there are induced draft fan and supercharged desulfurization fan in the desulfurization system of power plant, in which the desulfurization and oxygen booster fan is the Roots blower.
With this configuration, when the supercharged fan or other equipment in the desulfurization system fails and needs short-term maintenance, the smoke can be temporarily exhausted by bypass, which will not affect the efficiency of the induction fan and do not need to shut down the boiler as a whole, thus increasing the reliability of the equipment. There are also desulfurization units without supercharged fan for desulfurization, but only induced fan. At this time, the induced draft fan should overcome the resistance of boiler flue-air system and desulfurization device at the same time. Therefore, it is necessary to increase the full pressure of the induced draft fan. The centrifugal fan, axial fan with adjustable moving blades and axial fan with adjustable stationary blades can be used for desulfurization and boosting fan. The specific type of fan to be used depends on the specific conditions.
Position of booster fan in desulfurization system
The induced draft fan is placed behind the electric dust removal.
There are four layout modes for supercharged fan: the first one is before the original fume side of GGH; The second type is between the original fume side of GGH and the absorption tower. The third type is between the absorber and the GGH net fume side. Fourth type: behind the GGH net fume side.
Advantages and disadvantages: First, the power consumption of the booster fan is the highest due to the large flue gas flow, but the high temperature flue gas temperature is above the acid dew point, so the corrosion problem of the booster fan is not considered and the material requirement for the booster fan is low. The absorption tower operates at positive pressure, which is beneficial to improve the defogger effect. This method is widely used. Second: low temperature of flue gas, corrosion protection must be considered. In addition, the power consumption of the fan is small. However, due to the thermal resistance of the fan itself, the flue gas temperature will be high and the desulfurization efficiency will be reduced. The third type: at this time, the blower is mostly called "wet blower". The flue gas has the strongest corrosion on the blower, requiring higher material for the blower, increasing cost input and frequent maintenance. At this time, the absorber operates under negative pressure, which facilitates the entry of oxidized air into the absorber. It is easy to cause secondary water carryover of flue gas, pollution of demister and downstream pipeline. Fourth: The flue gas is dry and the power consumption of the fan is moderate, but it also needs high-strength anticorrosive material to increase the cost.