The desulfurization tower

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The desulfurization tower

(1) a limestone gypsum wet flue gas desulfurization

Limestone gypsum wet flue gas desulfurization technology is a mature technology in the world by the thermal power plant, the process is simple, reliable operation and convenient maintenance. Has strong reliability, high desulfurization efficiency, desulfurization by-product utilization, will cause two pollution etc.. The technology is the best choice for solving the problem of large capacity generating units for flue gas desulfurization, flue gas desulfurization project in coal-fired power plants, coal-fired heating boilers, metallurgical sintering machine enterprises, is the first choice of boiler exhaust gas purification.


This technology principle

Prepared using flue gas desulfurization limestone or lime slurry washing SO2, the reaction equation as follows:

SO2 H2O-H2S03 S03 H20-H2SO4: absorption

H2SO3-CaSO3 H2O CO2 CaCO3 and CaCO3 H2SO4-CaSO4 H2O CO2

CaCO3 HCl-CaCl2 H2O CO2 CaCO3 HF-CaF2 H2O CO2

Oxidation: CaSO3 O2-CaSO4

Crystal: CaSO4 H2O-CaSO4.2H2O

This technology features

1, high desulfurization efficiency can reach more than 95%;

2, chemical absorbent dose ratio is low, about 1.03;

3, liquid / gas ratio (L/G) is low, which can reduce the energy consumption of the desulfurization system;

4, can get high purity desulfurization by-product gypsum, creating favorable conditions for the comprehensive utilization of desulfurization by-products;

5, the empty tower type makes the decrease of absorption tower diameter greatly, while greatly reducing the internal components, reduce the possibility of scaling;

6, using cheap limestone / lime as absorbent, can effectively control the operation cost;

7, the system has high reliability, availability of system can reach more than 98%;

8 of the boiler and the coal quality variation adaptability, when the sulfur content of coal increases, can still maintain a high desulfurization efficiency;

9, to the change of the boiler load have good adaptability, and the concentration of SO2 in flue gas load under different stability of desulfurization system still maintained high system.

This flow chart


(2) ammonia flue gas desulfurization

Ammonia flue gas desulfurization technology using ammonia as absorbent for flue gas SO2 removal of pollutants in the flue gas purification technology. Ammonia is an alkaline absorbent good, from the analysis of chemical absorption mechanism, alkaline absorbent is stronger, more conducive to absorption; absorption from the analysis of physical mechanism on ammonia absorption SO2 gas - liquid or gas - gas reaction, reaction rate, reaction. It is because of ammonia desulfurization process itself some characteristics, has a certain appeal for some areas in china.


This process principle

Ammonia is ammonia into the absorption tower, which reacts with the smoke exposure, containing sulfur dioxide, removal of sulfur dioxide to achieve. The reaction equation as follows:

NH3 H20 S02-NH4HS03

NH3 H20 S02- (NH4) 2SO3

(NH4) 2S03 H20 S02-NH4HS03

The ammonia content is low, the first reaction occurs, in the ammonia content for a long time, the occurrence of the second responses, third said the real reaction reaction in ammonia absorption.

When more NH4HS03 reaction, need to add ammonia:

NH4HSO3 NH3- (NH4) 2SO3

Oxidation reaction:

(NH4) 2S03 02- (NH4) 2S04

This technology features

1, ammonia desulfurization system of sulfur content in coal wide adaptability

2, high desulfurization efficiency can reach more than 98%.

3, simple, low energy consumption

4, low operation cost, recycling of by-products

5, the desulfurization agent does not contain carbon, without increasing carbon dioxide emissions

This flow chart


(3) dual alkali flue gas desulfurization

Dual alkali flue gas desulfurization process is to overcome the limestone (lime) - gypsum method easily scaling shortcomings and develop. It first with the aqueous solution of alkali metal salt absorption of sulfur dioxide, and then use the lime or limestone will absorb sulfur dioxide in solution regeneration after another lime reactor, the regenerated absorption liquid recycling, the final product to precipitate calcium sulfite.


This process principle

I, the desulfurization process

Na2C03 S02, Na2S03 CO2

NaOH S02, Na2S03 H2O

Na2S03 S02 H20, NaHS03

The regeneration process of

NaHS03 Ca (OH) 2, Na2S03 CaSO3: H20

Na2S03 Ca (OH) 2, NaOH: CaS03

This technology features

1, reduce the equipment blocking, easy operation and maintenance of equipment

2, high purity gypsum by-product, the wide application range of some

3, due to the complex process control, improper operation, will appear in the scaling phenomenon

4, because the sodium sulfate by-product, need to continuously add sodium alkali and increase the consumption of alkali

This flow chart


Magnesium Oxide (4) flue gas desulfurization

Magnesium Oxide has high desulphurization rate, Recyclable sulfur, can avoid the generation of solid waste characteristics in magnesium ore resources in the region, is a kind of competitive desulfurization technology. The Magnesium Oxide method can be divided into cast method, regeneration method and oxidation and recovery method.


This process principle

The main reaction of MgO H20-Mg (OH) 2

Mg (OH) SO2 H20-MgSO36H20 2

MgSO3 S02 H20-Mg (HS03) 2

Mg (HS03) 2 Mg (OH) 2 H2O-MgS036H20

The oxidation of MgS03 O2 H2O-MgS047HZO

Mg (HS03) 202 H20-MgS047H20 02

This technology features

1, high desulfurization efficiency, high absorbent utilization rate, strong adaptability of unit.

2, liquid gas ratio, low height of absorption tower.

3, the absorbent preparation system is simple, small size.

4, the system is not easy to scale, no blockage, high reliability.

5, Magnesium Sulfate, Magnesium Sulfate and the by-product can be comprehensive utilization, with higher commercial value.

This flow chart


(5) SCR selective catalytic reduction denitration

SCR (Selective Catalytic Reduction) is a selective catalytic reduction technology, the rapid development in recent years, has been widely used in Western Europe and Japan, the ammonia catalytic reduction is the most applied technology. It has no by-products, not the formation of two pollution, and the device has the advantages of simple structure, high removal efficiency (above 90%), reliable operation, convenient maintenance.

This process principle

Selective refers to the action of the catalyst and in the presence of oxygen, NH3 and NOx preferred reduction reaction, the formation of nitrogen and water, and not in the flue gas oxygen oxidation reaction, the main reaction is:

NO NH3 02-N2 H20

N02 NH3 02-N2 H20

In the absence of the catalyst, the chemical reaction is carried out in a narrow temperature range, the catalyst of the reaction temperature can be controlled at 300-400 DEG C, the flue gas temperature equivalent between boiler economizer and air preheater, the reaction is an exothermic reaction, the concentration of NOx in the flue gas is low. So the reaction temperature can be ignored by the catalyst.

SCR denitration catalyst

As a catalyst for SCR denitration reaction core, its quality and performance is directly related to the denitration efficiency, therefore, denitrification project in power plant, in addition to not ignore the design of the reactor and the flue, equally crucial parameter design of catalysts.

In general, denitration catalyst for the project are tailored according to the project, the flue gas composition, characteristics, efficiency and customer requirements set. The performance of the catalyst (including activity, selectivity, stability and reproducibility) can not be directly quantified, but there are some main parameters in the comprehensive embodiment, activated temperature, geometric parameters, mechanical strength parameters, chemical composition, process performance index.

The type of catalyst: corrugated plate, honeycomb plate.

This flow chart

(6) SNCR selective non catalytic reduction denitration

Selective non catalytic reduction (Selective Non-catalytic, Reduction, SNCR) denitration technology, without the presence of catalyst, with reducing agent (ammonia and urea) reduction in the flue gas NOx into N2 and H2O.

In mid 80s the successful development of SNCR technology in foreign countries, used widely in medium and small units, to the early 90s successfully used in coal-fired power plant.

This is the only choice of technology to reduce nitrogen oxide without involving other oxides (such as CO2), the new SNCR NOx technology and effective range of the reaction temperature is over 850 DEG -1250 DEG.


This process principle

In the temperature range of 850~1100, NH3 or NOx as the main urea reduction reaction:

NH3 as a reducing agent

NH3 NO O2, N2 H2O

Urea as reducing agent

NO CO (NH2) 202 - N2 CO2 H2O

This flow chart


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