Desulfurization in thermal power plants mainly uses the limestone-gypsum method. The main function of the absorption tower is to use limestone slurry with a pH value of 5.0 to 6.0 in the slurry tank to remove sulfur dioxide from the. combustion gas. The reaction in the absorption tower can be divided into three zones: absorption zone, oxidation zone and neutralization zone. Reactions in the absorption zone:
Main reaction: SO2+H2O→H2SO3H2SO3→H++HSO3‐→2H++SO32‐
Partial reaction: H++HSO3‐ +1 / 2O2→2H++SO42‐
2H++SO42‐+CaCO3+H2O→CaSO4·2H2O+CO2
2. Denitrification and nitrogen removal mainly use SCR and SNCR processes, ?SCR It uses reducing agents (NH3, urea) under the action of metal catalysts to selectively react with NOx to generate N2 and H2O ; SNCR is a method for reducing NOx in the temperature range of 850 to 1100 °C;
NH3 as reducing agent:
4NO+4NH3+O2—>4N2+6H2O
2NO+4NH3+2O2—>3N2+6H2O
6NO2+8NH3—>7N2+12H2O
Thermal power plants use a suspension of limestone (the main component is calcium carbonate) to absorb the SO2 present in the waste in order to avoid environmental pollution and its reaction. The chemical equation of This is the most widely used desulfurization technology in the world. About 90% of flue gas desulfurization devices used in thermal power plants in Japan, Germany and the United States use this process.
(2) Flue gas desulfurization process by rotary spray drying
(3) Flue gas desulfurization process by ammonium phosphate fertilizer method< /p>
(4) Calcium Spray Tail in Furnace Humidified Flue Gas Desulfurization Process
(5) Fluidized Bed Desulfurization Process ccirculating flue gas
(6) Seawater desulfurization process
(7) Electron beam method Desulfurization process
( 8) Desulfurization process by ammonia washing method
Post-combustion desulfurization, also known as flue gas desulfurization (FGD for short), in FGD technology, depending on the agent desulfurization. The types are divided into the following five methods: calcium method based on CaCO3 (limestone), magnesium method based on MgO, sodium method based on Na2SO3, ammonia method based on NH3, alkali method organic based on the organic alkali method. The most widely used commercial technology worldwide is the calcium method, which accounts for more than 90%.
Thermal power plants use limestone slurry to absorb sulfur dioxide from exhaust gases to prevent environmental pollution:
SuLet's say you need lime containing 80% calcium carbonate.x grams of stone, you can get y grams of raw product containing 80% calcium sulfate
2CaCO3+2SO2+O2=2CaSO4 +2CO2
2*100 2*64 2*136
p>x*80% 6.4 y*80%
List the calculation of the proportion
x=200*6.4/(2*64*0.8)= 12.5 g
p>y=2*136*6.4/(2*64* 0.8)=17 g
2CaCO3+2SO2+O2=2CaSO4+2CO2.
200 128
x 1.6g
200/128=x/1.6g
x=2.5g