The method is as follows:
1. Limestone powder is added to water to make a slurry as an absorbent and pumped into the absorption tower to fully contact and mix with the flue gas. The sulfur dioxide in the flue gas and the calcium carbonate in the slurry And the air blown in from the lower part of the tower undergoes an oxidation reaction to generate calcium sulfate. After the calcium sulfate reaches a certain degree of saturation, it crystallizes to form dihydrate gypsum.
2. The gypsum slurry discharged from the absorption tower is concentrated and dehydrated to make the water content less than 10%. The conveyor is sent to the gypsum silo for stacking. The desulfurized flue gas passes through a demister to remove mist droplets. After being heated by the heat exchanger, it is discharged into the atmosphere through the chimney.
3. NID method principle: Ash powder enters the reactor after being digested by the lime digester (LDH), and chemically reacts with SO? in the flue gas to generate CaSO? and CaSO?, which are in the flue gas. The SO? is removed.
Explanation of related content:
At present, there are generally three desulfurization methods: pre-combustion, during combustion and post-combustion desulfurization. With the development of industry and the improvement of people's living standards, the thirst for energy is also increasing. SO2 in coal-fired flue gas has become the main cause of air pollution. Reducing SO2 pollution has become a top priority in today's atmospheric environment management. Many flue gas desulfurization processes have been widely used in industry, and they also have important practical significance for the treatment of exhaust gases from various boilers and incinerators.
The desulfurization absorption and product treatment of dry FGD technology are all carried out in a dry state. This method has the advantages of no sewage waste acid discharge, low equipment corrosion, and no obvious cooling and purification of flue gas during the purification process. It has the advantages of high rear flue temperature, conducive to the diffusion of chimney exhaust, and less secondary pollution. However, there are problems such as low desulfurization efficiency, slow reaction speed, and bulky equipment.
Semi-dry FGD technology means that the desulfurizer is desulfurized in a dry state and regenerated in a wet state (such as a water-washed activated carbon regeneration process), or desulfurization is performed in a wet state and the desulfurization product is processed in a dry state ( Flue gas desulfurization technology such as spray drying method).
In particular, the semi-dry method, which desulfurizes in a wet state and processes the desulfurization product in a dry state, has the advantages of fast wet desulfurization reaction speed and high desulfurization efficiency, and the dry method has no waste water. The advantages of waste acid discharge and desulfurization products being easy to handle have attracted widespread attention. According to the use of desulfurization products, it can be divided into two types: discard method and recovery method.