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Lime gypsum desulfurization equipment
Gypsum desulfurization is the most commonly used method for wet desulfurization.
Product details
Gypsum desulfurization is the most commonly used method for wet desulfurization.
The difference between this technology and the abandonment method is that air is blown into the slurry of the absorption tower to force CaSO3All oxidized to CaSO4(Gypsum), the by-product of desulfurization is gypsum. Simultaneously blowing in air produces a more uniform slurry, making it easier to achieve a 90% desulfurization rate and control scaling and blockage. Due to its low price and ease of transportation and preservation, limestone has been used since August 8th
Since the 2000s, limestone has become the main desulfurizer for gypsum method. When choosing flue gas desulfurization equipment for thermal power plants both domestically and internationally, the limestone/gypsum forced oxidation system has become the preferred wet flue gas desulfurization process.
Working principle
Limestone or lime is used as a desulfurization absorbent. Limestone is crushed into powder and mixed with water to form an absorbent slurry. When lime is used as the absorbent, the lime powder is digested and treated with water to make the absorbent slurry. In the absorption tower, the absorption slurry is mixed with the flue gas, and the sulfur dioxide in the flue gas reacts chemically with the calcium carbonate in the slurry and the injected oxidizing air to be removed. The final reaction product is gypsum.
technological process
Boiler/kiln ->Dust collector ->Induced draft fan ->Absorption tower ->Chimney
Desulfurization process
The flue gas from the boiler or kiln enters the absorption tower under the action of the induced draft fan after dust removal. The absorption tower is a countercurrent spray empty tower structure, integrating absorption and oxidation functions. The upper part is the absorption zone and the lower part is the oxidation zone. The flue gas after dust removal comes into reverse contact with the circulating slurry in the absorption tower. The system is generally equipped with 3-5 slurry circulation pumps, each corresponding to a layer of atomization spray layer. When only one unit is running or the load is low, 1-2 spray layers can be shut down, and the system still maintains a high liquid to gas ratio, thus achieving the desired desulfurization effect.
The upper part of the absorption zone is equipped with a secondary defogger, and the free moisture in the flue gas at the outlet of the defogger does not exceed 75mg/Nm3. After absorbing SO2, the slurry enters the circulating oxidation zone, where calcium sulfite is oxidized into gypsum crystals by the air blown in. At the same time, fresh limestone slurry is supplied from the absorbent preparation system to the absorption oxidation system to supplement the consumed limestone and maintain a certain pH value of the absorption slurry. When the reaction product slurry reaches a certain density, it is discharged into the desulfurization by-product system and dehydrated to form gypsum.
principle
Desulfurization process
CaCO3+SO2+1/2H2O→CaSO3·1/2H2O+CO2
Ca(OH)2+SO2→CaSO3·1/2H2O+1/2H2O
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