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FGD System

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Circulating fluidized bed semi-dry flue gas desulfurization(CFG-FGD) system is a typical application of semi-dry flue gas desulfurization technology. The flue gas desulfurization technology uses acid-base reaction and gas-solid mass transfer in a circulating fluidized bed, the suspension method is adopted to make the absorbent (slaked lime) circulate repeatedly between the desulfurization tower and the dust collector. Under the action of water, it fully contacts with the acid gas in the flue gas to produce a chemical reaction, and prolongs the contact time between the absorbent and the flue gas to achieve the purpose of efficient desulfurization.

FGD system
FGD System

The waste gas is processed by the FGD system, and the SO2, SO3, HCl, HF, and H2S in the flue gas are effectively removed. The desulfurization by-product desulfurization ash of the semi-dry FGD system is a free-flowing dry powder mixture, without secondary pollution, and can be further comprehensively utilized.

Semi-dry Flue Gas Desulfurization Technology Apply Scope

Application scope of flue gas desulfurization technology
Application scope of flue gas desulfurization technology
Pollutant categorySO2, SO3, HF, HCl, H2S, Dioxin
SO2 contantat inlet100~10000mg/Nm3
Flue gas Temp. at inet:~150℃(Max. 240)
Flue gas volume1000~1M Nm3/h
Flue Gas DesulfurizationTechnology Apply Scope

Semi Dry FGD System Composition

The semi dry FGD system in the FGD plant is mainly composed of the following technical links:

  • Absorbent bin and delivery system
  • Circulating fluidized bed reaction tower
  • Bag house de-dusting system
  • Absorbent re-circulating system
  • Process water system
  • Flue gas system
  • Desulfurized fly ash delivery system

The absorbent used in the flue gas desulfurization process is the finished slaked lime powder, and the reaction tower adopts a circulating fluidized bed.

Flue Gas Desulfurization Process in FGD Plant

Flue Gas Desulfurization Process in FGD Plant
Flue Gas Desulfurization Process in FGD Plant

The basic reaction principle of semi-dry flue gas desulfurization is to use water spray to humidify and activate the desulfurizer and make it repeatedly used.

  1. The flue gas enters from the venturi in the lower part of the reaction tower, and after accelerating the turbulence at the throat, it mixes vigorously with high-concentration Ca(OH)2 powder and atomized water in the divergent section, and absorbs and reacts with SO2, SO3, etc.
  2. The desulfurization agent is in a suspended fluidized state, the reaction surface area is large, the heat/mass transfer conditions are many, and the particles continue to collide and react. Then the flue gas with a large amount of dust enters the dust collector. The solid particles collected by the dust collector are returned to the fluidized bed reactor and continue to participate in the desulfurization reaction process. The circulation volume can be adjusted according to the load.
  3. In the flue gas desulfurization process, a water mist nozzle is set at the entrance of the reaction tower to reduce the temperature of the flue gas on the one hand, and form a liquid phase on the surface of the Ca(OH)2 particles on the other hand, which can activate the gas-solid reaction and accelerate the absorption process.

Ca(OH)2+ SO2→CaSO3+H2O

Ca(OH)2+ SO2+1/2O2→CaSO4+H2O

Ca(OH)2+ SO3→CaSO4+H2O

Technical Features of CFG-FGD System

1. The semi-dry desulfurization process is simple, the overall cost is only 40%-50% of the wet desulfurization process, and there are few rotating parts, which improves the reliability of the system and reduces the maintenance and repair costs.

2.High desulfurization efficiency: when the calcium-sulfur ratio is 1.1 to 1.25, the removal rate of SO2 is 90-95%, and the removal rate of SO3, HF, and HCl is more than 99%.

3. It can effectively remove harmful gases such as SO2, SO3, chloride and fluoride, and its removal efficiency is much higher than that of wet process, reaching 90% to 99%.

4. The slaked lime and water added to the desulfurization tower are relatively independent. There is no shotcrete system and slurry nozzle, which is convenient to control the amount of slaked lime and water spray, and it is easy to control the operating temperature.

Why Choose Ruichang CFG-FGD System?

FGD system desulfurization by-products have good fluidity and are easy to handle. They are “general industrial solid wastes”. They are verified by GB 5085.3-2007Hazardous Waste Identification Standards for Leaching Toxicity Identification“. They are not classified as hazardous wastes with leaching toxicity and are not corrosive. Disposal such as stacking, landfilling, backfilling, and road construction will not affect the groundwater environment. We conducted field tests on the Ruichang FGD system, and the performance index data obtained showed that the performance of the system was at the upstream level.

SO2 emission concentration<80mg/Nm3
Particle emission concentration<20mg/Nm3
Desulfurizing agent economical operation consumptionCa/S=1:1.25
Desulfurization efficiency>95%
De-dust efficiency>99.99%
Device usage rate100%
Tower corrosion<0.01mm
System pressure drop<3KPaG
Site Testing Data
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