Double-oxidation ammonia desulfurization process and device

Abstract

The invention discloses a double-oxidation ammonia desulfurization process and a double-oxidation ammonia desulfurization device. The device comprises an ammonia water preparation device, an absorption tower, a pre-scrubber, a buffer oxidation tank, a cyclone, a centrifugal machine, a drying bed, a tail gas scrubber, a packaging machine and an ammonia water storage tank. Sulfur dioxide is removedfrom flue gas by liquid ammonia, and ammonium sulfate crystals with the purity of over 99 percent are obtained; and the invention has the advantages that: the cost of the conventional ammonia desulfurization is reduced, the absorption efficiency is improved, the desulfurization efficiency is over 95 percent, the yield is improved, the ammonium sulfate crystals with the purity of over 99 percent are obtained, the waste is changed into treasure, economic benefit is increased, the ammonium sulfate yield is over 96 percent, and the ammonia escape volume is reduced and is less than 8mg/m<3>.

Description

technical field [0001] The invention relates to a flue gas desulfurization process, in particular to a double ammonia oxidation desulfurization process and device, which uses liquid ammonia to remove sulfur dioxide in flue gas, and belongs to the field of chemical industry. Background technique [0002] With the development of economy, the progress of society and the enhancement of people's awareness of environmental protection, the removal of SO2 from industrial flue gas has been paid more and more attention. [0003] Ammonia desulfurization process is based on ammonia and SO 2 , The basic mechanism of water reaction to generate desulfurization products, mainly wet ammonia method, electron beam ammonia method, pulse corona ammonia method, simple ammonia method and so on. [0004] The wet ammonia desulfurization process system is mainly composed of desulfurization washing system, flue gas system, ammonia storage system, ammonium sulfate production system (if it is not the a...

AI Technical Summary

Problems solved by technology

[0005]At present, the desulfurization tower in most ammonia desulfurization processes mainly adopts the absorption liquid spray absorption method, which will mainly cause the outlet flue gas A large amount of ammonia escape will cause secondary pollution to the surrounding environment

There are also some desulfurization towers that use trays to absorb sulfides, but because the temperature of the flue gas is difficult to drop to the optimum temperature of 60°C for desulfurization when passing through the trays, the absorption liquid on the trays absorbs the sulfides in the flue gas Finally, under high temperature conditions, it will be decomposed soon. Only by adding excessive ammonia to absorb the sulfide in the flue gas, this will cause a large amount of absorbent, which is uneconomical, and the amount of ammonia slip at the outlet is also large, and the outlet is decomposed. The sulfide and ammonia escape will continue to react, the by-products will be attached to the outlet flue, the amount of by-products that can be collected is small, and the outlet flue is easy to block

There is also a form of spraying under the tray of the desulfurization tower, but this absorption method basically relies on tray absorption. In order to ensure the desulfurization rate, it is necessary to ensure the reaction time of the flue gas passing through the tray and the absorption liquid on the tray. Therefore The hole spacing of the tray design is small, the resistance is large, and the energy consumption is high. When the flue gas passes through the liquid film of the tray, the droplet entrainment is serious

[0006] Yet by oxidation in the absorption tower, it is difficult to ensure that the ammonium sulfate oxidation time is greater than 2 hours and the optimum pH value is 5.5, thus it is difficult to produce ammonium sulfate; The first is oxidation in the concentration section. However, because the ammonium sulfite is unstable, it begins to decompose at a temperature above 60°C. If the concentration section is oxidized, the high-temperature flue gas above 130°C will decompose a large amount of ammonium sulfite, which also reduces the absorption efficiency and is difficult. ammonium sulfate

[0007] Chinese patent 200310115523.2 provides an integrated desulfurization and dedusting tower with ammonia method. The desulfurization and dedusting tower is equipped with a first-stage spraying section and a tray layer from bottom to top And the demister, the disadvantage of this device is that it is not suitable for handling large amounts of flue gas, and when the tower diameter of the desulfurization tower is large, the solution on the tray is difficult to distribute evenly

However, due to the use of oxidation treatment in the tower, this process and device will affect the desulfurization rate of the entire desulfurization system. If in order to ensure the desulfurization rate, excessive ammonia gas is added for absorption, and the ammonia escape in the outlet flue gas will inevitably exceed the standard.

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