Why do desulfurization towers rarely use tower types common in the chemical industry?
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At present, the mainstream desulfurization process is the limestone method, and the mainstream tower type of the desulfurization tower is the spray empty tower. It is said that the flue gas volume of the power station boiler is large and the gypsum is easy to block. Using an empty tower can reduce the system resistance and prevent clogging. However, I think the absorption efficiency of the empty tower is low and requires a large liquid-gas ratio. In this way, although the lower system resistance can reduce the power of the fan, the low absorption efficiency and the need for a larger liquid-gas ratio have significantly increased the power of the absorption circulation pump. I think desulfurization, regardless of whether it uses limestone method, magnesium oxide method, ammonia method, caustic soda method, etc., belongs to chemical absorption. As for chemical absorption, the chemical industry has thoroughly studied it. There are also many low-resistance, high-efficiency and anti-blocking tower types. Why do desulfurization towers rarely use tower types common in the chemical industry? This can greatly improve the absorption efficiency and reduce the power consumption of the desulfurization circulation pump. Discussions welcome.
What are the tower types with low resistance, high efficiency and anti-clogging, cyclone plate tower?
First, the pressure of the raw gas is low. To overcome the resistance drop of the absorption tower by increasing the pressure of the raw gas, the power of the raw material fan needs to be increased, which also consumes a lot of power and is not worth the gain. Secondly, as the pressure increases, the wall thickness of the absorption tower needs to be increased. The equipment of the absorption tower is very large. If the wall thickness is increased a little, the investment in equipment will increase significantly. At present, desulfurization is basically losing money. Who is willing to invest huge amounts of money and continue to lose money?
This is the summary result of practical experience. I don't know what those low-group and high-resistance towers you're talking about are. Even though empty towers are currently the mainstream, the problem of clogging of the demister structure has not been solved. If it is not feasible to use a packed tower or a plate tower, and the blockage is high and the resistance is more serious, it is not just a matter of low desulfurization rate. It would be good if it can operate normally. As far as I know, the tower with the lowest resistance in China is probably Suyuan's U-shaped meandering advection tower. It is also an empty tower, but it is not in counter-flow contact with the absorbent, but in cross-flow contact, which reduces the absorption resistance. It is said that the efficiency can reach 90%. If the original poster really has the low-impedance and high-resistance tower type he mentioned, I hope you can enlighten me.
The most commonly used packing tower in the chemical industry is the packed tower. However, the packed tower cannot be used for flue gas desulfurization. The main reason is that the packed tower occupies a large area and is easy to block. Moreover, the resistance of the packed tower is relatively large. The nature of the flue gas from the power plant boiler also limits its use. There is always dust in the flue gas of the power plant, which inevitably leads to the possibility of blockage.
The main reason is that the limestone gypsum method cannot use packed tower magnesium oxide for desulfurization. I have seen Japanese technology that uses packed towers, and it should still be feasible.
It seems that the poster has never done any operation. The problem faced by the desulfurization project is not efficiency, but how to operate stably. The most important thing about this kind of tower is to prevent clogging. This problem should be viewed from an engineer’s perspective
The limestone process absorbent operates in the form of slurry, which is very easy to scale and block. At the beginning of the development of the wet process, some used packed towers. Sichuan Luohuang Power Plant used grid packing. The blockage was very serious, and later it was changed to a spray empty tower. Packed towers are very commonly used in magnesium process, ammonia process and seawater desulfurization.