CN104190193A - Method for performing synchronous desulfurization, denitrification and dust removal in bag type dust collector - Google Patents

Abstract

The invention discloses a method for synchronous desulfurization, denitrification and dust removal in a bag filter, which is characterized in that: the bag filter is used as a reaction device, and the coal-fired flue gas after electric dust removal is introduced into the bag filter through a connecting pipe , inject manganese oxide into the connecting pipe to make the manganese oxide desulfurize and denitrify the coal-fired flue gas; the unreacted manganese oxide, desulfurization and denitrification products and soot enter the filter bag of the bag filter with the coal-fired flue gas , and is trapped on the surface of the filter bag to form a filter layer; inject ammonia gas into the coal-fired flue gas entering the bag filter, and the ammonia gas will reduce the remaining nitrogen oxides in the coal-fired flue gas to nitrogen; After regeneration, the obtained manganese oxide is recycled to the injection connection pipeline. The present invention takes the bag filter as the core device, uses manganese oxide as the active material, and realizes the synchronization and integration of flue gas desulfurization, denitrification and dust removal in the bag filter through a series of separation, regeneration treatment and recycling.

Description

A method for synchronous desulfurization, denitrification and dust removal in a bag filter

1. Technical field

The invention relates to the field of air pollution control, in particular to a method for synchronous desulfurization, denitrification and dust removal of flue gas.

2. Background technology

Thermal power plants produce a large amount of pollutants such as SO ₂ , NO _x , and soot during high-temperature combustion. Nitrogen oxides in the air are the main source of fine particulate matter PM2.5, and thermal power plants are the largest emitters of nitrogen oxides. Therefore, it is imperative to denitrify power plants and reduce PM2.5 concentration without delay. Nitrogen oxides can also cause regional environmental pollution problems such as photochemical smog and ozone layer depletion. Due to SO ₂ and NO _x emissions, acid rain has occurred in 81.6% of cities across the country, and severe weather such as smog has increased nationwide, which has seriously affected industrial and agricultural production, people's lives, and human health.

At present, flue gas desulfurization has been implemented in coal-fired power generating units across the country. Lime or limestone is generally used as desulfurization material for dry or wet desulfurization. Electric dust removal is generally used for flue gas dust removal. The desulfurization and dust removal effects can basically meet the emission requirements. However, in order to protect the atmosphere Environmental quality requires further development of new environmental protection technologies to improve desulfurization and dust removal efficiency and reduce sulfur dioxide and smoke emissions.

Flue gas NO _x pollution control, that is, flue gas denitrification, includes absorption method, adsorption method, non-selective catalytic reduction (SNCR) and selective catalytic reduction (SCR), etc. SCR technology has been widely used in foreign flue gas denitrification projects because of its high denitrification efficiency. The SCR method uses ammonia or urea as a reducing agent to selectively reduce NO _x in flue gas to N ₂ under the action of a catalyst. At present, domestic power plants have introduced foreign commercial denitration catalyst WO ₃ -V ₂ O ₅ /TiO ₂ and its technology is being promoted. The shortcomings of this type of catalyst are: first, the cost of catalytic preparation is high, and the toxicity is strong, and the workers must wear gas masks during installation. The service life of the catalyst is 3 years, and it is difficult to handle after the catalyst fails; V ₂ O ₅ has a catalytic effect on the oxidation of SO ₂ to SO _{3 , and the generated SO 3 reacts} with NH ₃ and water vapor in the flue gas to form NH ₄ HSO ₄ , which condenses when it is lower than its dew point (300-330°C) Causes blockage and corrosion on equipment and piping. The third is that the reaction temperature required for the denitrification of this type of catalyst is relatively high (300-400°C), which is not suitable for the actual situation that the flue gas desulfurization and dust removal of existing power plants in my country are relatively low.

The development of low-temperature catalysts can make the reaction proceed at a lower temperature (about 200 ° C), which can not only reduce the energy consumption and cost of the reaction; it can also be considered to place the SCR device after the ESP (electrical dust removal) to reduce or completely eliminate SO ₂ Effects on catalysts. The low-temperature SCR denitration catalysts mentioned in domestic and foreign literature are mainly MnO _x /TiO ₂ , MnO _x /AC, MnO _x /Al ₂ O ₃ , MnO _x /attapulgite, and MnO _x prepared by impregnation method, which have high Activity and water vapor has little effect on the activity of the catalyst, but SO ₂ in the flue gas will have a greater side effect on the reaction activity, especially for the MnO _x catalyst. Domestic published patent (CN101352681) discloses the preparation of low-temperature SCR catalysts using activated carbon as a support for impregnating and supporting Mn, V, Cu, Co, Fe oxides; published patent (CN101011659) discloses using activated carbon as a support for impregnating and supporting MnO _x /CeO ₂ Preparation of low temperature SCR catalyst. The advantage of the catalyst prepared with activated carbon as the carrier is that the rich specific surface area of the activated carbon carrier is conducive to the dispersion of the active components, and has a certain anti- _SO2 performance, but the high-temperature ablation of the activated carbon is too severe during the activation and regeneration process, resulting in excessive catalyst loss big. A thermal power plant in Shandong Province used rare earth catalysts, and the concentration of nitrogen oxides in the flue gas was 450 mg/Nm ³ , which dropped to below 90 mg/Nm ³ , and the removal rate reached 80%. However, none of these technologies can realize the integration of desulfurization and denitrification.

With the research and development of flue gas desulfurization, denitrification, and dust removal technologies, it has been gradually recognized that the integration of desulfurization and denitrification is the future development trend, which can reduce the process of flue gas pollution treatment, reduce the investment in desulfurization and denitrification and the cost of flue gas pollution control .

According to the current research, manganese oxide has both high desulfurization activity and high SCR denitrification activity. Using manganese oxide as the active material for desulfurization and denitrification to select a suitable method to achieve simultaneous desulfurization and denitrification, and to further reduce the concentration of soot is a promising technology.

3. Contents of the invention

Aiming at the problems existing in the comprehensive treatment of flue gas pollution, the present invention invents a method for synchronous desulfurization, denitrification and dust removal in a bag filter, aiming at realizing synchronous desulfurization and denitrification, and further reducing the concentration of smoke and dust.

The present invention solves technical problem, adopts following technical scheme:

The method for synchronous desulfurization, denitrification and dust removal in the bag filter of the present invention is characterized in that:

Using the bag filter as the reaction device, the coal-fired flue gas after electrostatic precipitating is introduced into the bag filter through the connecting pipe, and manganese oxide is injected into the connecting pipe to make the manganese oxide remove the coal-fired flue gas. Most of the sulfur dioxide in the sulfur dioxide forms manganese sulfate, and part of the nitrogen oxides is removed to form manganese nitrate; The remaining soot in the gas, after the circulation of manganese oxide, the soot here includes the remaining soot in the coal-fired flue gas after electrostatic precipitator, and also includes when the solid I is used as manganese oxide for recycling, the soot in the solid I The soot) enters the bag filter along with the coal-fired flue gas, and is trapped on the surface of the filter bag of the bag filter to form a filter layer; the unreacted manganese oxide in the filter layer continues to remain with the coal-fired flue gas Sulfur dioxide reaction; inject ammonia gas into the coal-fired flue gas entering the bag filter, under the catalysis of unreacted manganese oxides in the filter layer, ammonia gas will reduce the remaining nitrogen oxides in the coal-fired flue gas is nitrogen;

As the thickness of the filter layer increases, the filter resistance of the filter bag increases. When the pressure drop in the filter bag reaches 800-900Pa, the filter layer is removed by electromagnetic rapping or pulse blowing and the filter layer material is collected. After the filter layer material is recovered Regeneration is carried out and the obtained manganese oxides are recycled to the injection connection pipeline.

The method for synchronous desulfurization, denitrification and dust removal in the bag filter of the present invention is also characterized in that:

The mass ratio of the manganese oxide injected into the connecting pipeline to the sulfur dioxide in the coal-fired flue gas delivered to the connecting pipeline is 2:1-5:1.

The mass ratio of the ammonia gas injected into the coal-fired flue gas of the bag filter to the nitrogen oxides in the coal-fired flue gas entering the bag filter is 1:1 to 1:1.15.

Before the coal-fired flue gas enters the bag filter, adjust the temperature of the coal-fired flue gas to stabilize the temperature of the coal-fired flue gas in the bag filter at 150-220°C to ensure the temperature requirements of the out-of-stock reaction and the safe use of the filter bag.

The method of regenerating the filter layer material to obtain manganese oxide is: adding 3 to 10 times the mass of water to the filter layer material to obtain a solid-liquid mixture I, and separating the solid-liquid mixture I to obtain the manganese oxide Solid I composed of smoke and dust and liquid I composed of manganese sulfate and manganese nitrate dissolved in water;

Neutralize the liquid I with ammonia water until the pH value is in the range of 8-9, then aerate and oxygenate the divalent manganese ions to be oxidized to tetravalent manganese ions to obtain the solid-liquid mixture II, and perform solid-liquid separation on the solid-liquid mixture II , to obtain a solid II composed of manganese oxides and a liquid II rich in ammonium sulfate and ammonium nitrate;

Mix solid I and solid II to obtain recycled manganese oxide slurry, or mix solid I and solid II and then boil and oxidize at 300-500°C or rotary kiln for 10-40 minutes in an air atmosphere to obtain recycled manganese oxide Powder; use the recovered manganese oxide slurry or the recovered manganese oxide powder as the manganese oxide, and inject it into the coal smoke from the connecting pipeline connected between the electrostatic precipitator and the bag filter Air recycling.

The method for synchronous desulfurization, denitrification and dust removal in the bag filter of the present invention takes the following steps:

a. First pass the coal-fired flue gas through the electrostatic precipitator to remove most of the dust. When burning high-sulfur pulverized coal so that the sulfur content in the coal-fired flue gas is higher than 800PPm, first add high-sulfur pulverized coal to the high-sulfur pulverized coal 1-3% by mass of limestone powder for re-burning;

b. Before introducing the coal-fired flue gas after electrostatic precipitator into the bag filter through the connecting pipe, adjust the temperature of the coal-fired flue gas so that the temperature of the coal-fired flue gas in the bag filter is stable at 150-220°C to ensure out-of-stock The temperature requirements of the reaction and the safe use requirements of the filter bag;

c. Inject manganese oxide into the coal-fired flue gas in the connecting pipe between the electrostatic precipitator and the bag filter, so that the manganese oxide can quickly react with the sulfur dioxide in the coal-fired flue gas, and remove the coal-fired flue gas Most of the sulfur dioxide in the sulfur dioxide forms manganese sulfate, and reacts with part of the nitrogen oxides in the coal-fired flue gas, and the nitrogen oxides are removed to form manganese nitrate; manganese sulfate, manganese nitrate, unreacted manganese oxides and smoke The gas enters the bag filter and is trapped on the surface of the filter bag of the bag filter to form a filter layer; the unreacted manganese oxide in the filter layer continues to react with the residual sulfur dioxide in the coal-fired flue gas; the added The mass ratio of the manganese oxide to the sulfur dioxide in the coal-fired flue gas transported to the connecting pipeline is 2:1 to 5:1;

d. Spray ammonia gas into the coal-fired flue gas entering the bag filter, and the unreacted manganese oxide in the filter layer on the surface of the filter bag is used as a selective catalytic reduction catalyst to exert high-efficiency denitrification in the temperature range of 150°C to 220°C Catalysis, so that ammonia can reduce the remaining nitrogen oxides in the coal-fired flue gas to nitrogen; The mass ratio of oxides is 1:1～1:1.15;

e. As the thickness of the filter layer on the surface of the filter bag increases, the filter resistance of the filter bag increases. When the pressure drop in the filter bag reaches 800-900Pa, the filter bag is vibrated by electromagnetically controlled rapping device or pulsating blowing. Layer material falls off and enters the ash hopper;

f. Collect the filter layer material in the ash hopper, and add 3 to 10 times the quality of water to dissolve the manganese sulfate and manganese nitrate in the filter layer material to obtain the solid-liquid mixture I, and solid-liquid mixture I is solidified After liquid separation, a solid I composed of manganese oxides and soot and a liquid I composed of manganese sulfate and manganese nitrate dissolved in water are obtained;

g. Neutralize liquid I with ammonia water until the pH of the liquid is in the range of 8 to 9, then aerate and oxygenate divalent manganese ions to tetravalent manganese ions to obtain solid-liquid mixture II, and carry out solid-liquid mixture II for solid-liquid mixture II separation to obtain a solid II consisting of manganese oxides and a liquid II rich in ammonium sulfate and ammonium nitrate;

h. Mix solid I and solid II to obtain recovered manganese oxide slurry, or mix solid I and solid II and boil and oxidize at 300-500°C or rotary kiln for 10-40 minutes in an air atmosphere to obtain recovered manganese Oxide powder: using the recovered manganese oxide slurry or the recovered manganese oxide powder as the manganese oxide used in step c, spraying it into the coal-fired flue gas from the connecting pipeline for recycling.

Solid ammonium sulfate and ammonium nitrate are obtained by concentrating and crystallizing the liquid II produced during the regeneration process of the filter layer material.

As the solid I obtained after the filter layer material is dissolved in water is continuously circulated, the soot component in the solid I is accumulated, and the proportion of the soot increases. When the soot content in the solid I is higher than 90%, the solid I is directly discarded for 5- 20%, and add new manganese oxide of the same quality as the discarded part to the remaining solid I, and then mix it with solid II for recycling.

The solid I obtained after the filter layer material is dissolved in water is continuously circulated, resulting in the accumulation of soot components in the solid I. When the soot content in the solid I is higher than 85%, the soot in the solid I is removed as follows, and then recycled: Inject the solid I as manganese oxide into the connecting pipe, so that the sulfur dioxide and nitrogen oxides in the coal-fired flue gas completely reduce the tetravalent manganese ions in the solid I to divalent manganese ions, and generate manganese sulfate and manganese nitrate, sulfuric acid Manganese, manganese nitrate and soot enter the filter bag of the bag filter along with the coal-fired flue gas, and are trapped on the surface of the filter bag to form a filter layer; the filter layer is removed and collected by means of electromagnetic rapping or pulse blowing Material, the filter layer material is dissolved in water to obtain a solid-liquid mixture, after solid-liquid separation, the obtained liquid is a liquid composed of manganese sulfate and manganese nitrate dissolved in water, and the obtained solid is soot, which is recovered by dissolving manganese sulfate and manganese nitrate in water. The liquid composed of water is regenerated into manganese oxide, and the dust is discarded, and the dust in the solid I is removed in this way, and then recycled; the amount of the solid I added is based on the molar ratio of tetravalent manganese to sulfur dioxide in the coal-fired flue gas 0.9:1 to 1:1.

The initially used manganese oxides are manganese nodule powder, natural high-grade manganese oxide ore powder, and industrial manganese dioxide powder.

Compared with the prior art, the innovation of the present invention and the achieved effects are reflected in:

The present invention uses the bag filter as the core device and reactor, uses manganese oxide as the active material, and through a series of separation, regeneration treatment and recycling, realizes the synchronization and integration of flue gas desulfurization, denitrification and dust removal in the bag filter change.

The bag filter of the present invention is arranged after the electrostatic precipitator, which removes most of the soot particles in the coal-fired flue gas, not only reduces the load of the bag filter, but also plays the role of the bag filter to supplement dust, and at the same time , can reduce the content of soot in manganese oxide circulating materials, reduce the amount of manganese oxide separation, regeneration, and recycling systems, and reduce processing costs.

Manganese is a valence-changing element, and it mainly presents divalent manganese and tetravalent manganese in the air environment. Quadrivalent manganese has strong oxidizing properties and is easy to oxidize reducing substances such as sulfur dioxide. At the same time, divalent manganese ions in water are neutral 1. Under alkaline conditions, it is easy to be oxidized by air to become tetravalent manganese, or the precipitation of divalent manganese is easily oxidized by oxide tetravalent manganese oxide when heated in air. The present invention utilizes this characteristic of manganese element and its compound, It not only realizes desulfurization but also realizes the regeneration of manganese oxide very conveniently.

Spray manganese oxide slurry or powder into the connecting pipeline between the electrostatic precipitator and the bag filter, and use the high activity of the redox reaction between manganese oxide and sulfur dioxide to quickly remove sulfur dioxide in the flue gas (reaction Equation 1), manganese oxides also have the effect of oxidizing nitrogen oxides in flue gas to form manganese nitrate (reaction equation 2).

As shown in Figure 1, the filter bag not only intercepts desulfurization product manganese sulfate, out-of-market product manganese nitrate, unreacted manganese oxide, but also retains the remaining soot particles in the coal-fired flue gas, as a supplement to electrostatic precipitator, improving the dust removal effect. At the same time, the particle layer rich in manganese oxides formed on the surface of the filter bag is also a catalyst for catalyzing the reduction and denitrification of ammonia (reaction equation 3).

Manganese oxides directly oxidize sulfur dioxide and nitrogen oxides to form sulfates and nitrates. The reaction equation is as follows:

MnO ₂ +SO ₂ =====MnSO ₄ (1)

2NO+O ₂ +MnO ₂ =====Mn(NO ₃ ) ₂ (2)

Manganese oxides as catalysts for ammonia reduction of nitrogen oxides in flue gas

6NO+4NH ₃ =====5N ₂ +6H ₂ O (3)

The filter layer on the filter bag is mainly dust, manganese oxide and its desulfurization and denitrification reaction products. When the pressure drop of the filter bag exceeds the requirement, the filter layer will fall off and enter the ash hopper by means of general electromagnetic vibration or pulse injection. In order to regenerate and recover manganese oxide, the material in the ash hopper is dissolved in water to extract manganese sulfate, and solid-liquid separation is performed to obtain solid I and liquid I. Solid I is mainly unreacted manganese oxide and soot. Liquid I mainly contains manganese sulfate and manganese nitrate, and manganese oxide solid II and liquid II are recovered through ammonia neutralization, aeration oxidation, and solid-liquid separation. Liquid II is a mixed solution of ammonium sulfate and ammonium nitrate, which can be further recycled. Mix solid I and solid II to form a slurry or mix them and roast them into powder and store them in a silo, and then add manganese oxides to the flue gas by spraying again for simultaneous desulfurization, denitrification and dust removal. Through a series of treatments on the material of the filter layer of the filter bag, manganese oxides are regenerated, recovered and recycled (as shown in Figure 2).

In order to eliminate the accumulation of soot substances in manganese oxide and affect the efficiency of manganese oxide cycle for desulfurization and denitrification, by reducing the amount of manganese oxide injected into the flue gas, the metering ratio is changed to tetravalent manganese in manganese oxide and fuel. The molar ratio of sulfur dioxide in the coal flue gas is 0.9:1~1:1, and the addition of ammonia gas to the flue gas is stopped, and only the flue gas desulfurization is carried out, so that the manganese oxide added is completely converted into manganese sulfate, and the filter bag is recovered After the manganese sulfate is extracted by water-soluble ash, the undissolved solids are mainly soot, which will be treated as waste. In this way, the soot accumulation in the manganese oxide circulating slurry can be eliminated.

As the manganese oxide slurry or powder is sprayed into the flue gas flow, it is rapidly mixed and dispersed into fine particles by the power of the flue gas, and undergoes redox reactions with flue gas sulfur dioxide and nitrogen oxides in a suspended state, and is trapped in the filter bag to form After the filter layer, the unreacted manganese oxides continue to undergo oxidation-reduction reactions with the sulfur dioxide and nitrogen oxides in the gas passing through the filter layer, which overcomes the defects of low desulfurization efficiency of the limestone dry method and a large proportion of limestone added, and can also overcome the wet method. Desulfurization reduces the temperature of flue gas more, cannot meet the temperature requirements of denitrification, and is not conducive to the problem of denitrification.

The present invention uses the filter bag as the core reaction device, which not only utilizes the high surface area of the filter bag, reduces the flue gas load per unit area, but also intercepts and recovers the desulfurization and denitrification products, and at the same time, the unreacted manganese oxide is used as the SCR catalyst, and the filter bag becomes a The carrier of the fixed bed of catalyst, the electromagnetically controlled rapping device removes the spent catalyst bed and regenerates it.

4. Description of drawings

Figure 1 is a schematic diagram of the principle of synchronous desulfurization, denitrification and dust removal of flue gas by using a bag filter;

Figure 2 is a schematic diagram of the technical route for synchronous desulfurization, denitrification and dust removal of coal-fired flue gas.

5. Specific examples

Example 1

As shown in Figure 1 and Figure 2, this embodiment illustrates the method for synchronous desulfurization, denitrification and dust removal in the bag filter of the present invention, and the specific steps are:

a. The coal-fired flue gas produced by burning coal powder is passed through an electric precipitator to remove most of the dust, and the sulfur content in the flue gas is about 550PPm;

b. Adjust the temperature of coal-fired flue gas after electrostatic precipitator to keep it stable at 200-210°C; in this way, the temperature of coal-fired flue gas entering the bag filter can be stabilized at 200-210°C. The temperature requirements of ammonia reduction flue gas denitrification also meet the requirements of safety and service life of filter bags.

c. Inject industrial manganese dioxide powder into the connecting pipe between the electrostatic precipitator and the bag filter, so that the manganese oxide can quickly react with the sulfur dioxide in the coal-fired flue gas, and remove most of the sulfur dioxide in the coal-fired flue gas Manganese sulfate is formed, and reacts with part of the nitrogen oxides in the coal-fired flue gas, and the nitrogen oxides are removed to form manganese nitrate; manganese sulfate, manganese nitrate, unreacted manganese oxides and smoke enter the bag bag In the filter bag of the dust collector, it is trapped on the surface of the filter bag to form a filter layer, and the purified flue gas is discharged through the filter bag; the unreacted manganese oxide in the filter layer continues to react with the residual sulfur dioxide in the coal-fired flue gas; The mass ratio of the added manganese oxide to the sulfur dioxide in the coal-fired flue gas delivered to the connecting pipeline is 3:1;

d. Spray ammonia gas into the coal-fired flue gas of the bag filter, and the unreacted manganese oxide in the filter layer on the surface of the filter bag acts as a selective catalytic reduction catalyst to play an efficient denitrification catalytic effect, so that the ammonia gas will burn coal The remaining nitrogen oxides in the flue gas are reduced to nitrogen; the mass ratio of the injected ammonia gas to the nitrogen oxides in the coal-fired flue gas entering the filter bag is 1:1;

e. As the thickness of the filter layer on the surface of the filter bag (composed of soot, manganese oxides and their desulfurization and depinning reaction products manganese sulfate and manganese nitrate) increases, the filter resistance of the filter bag increases. When the pressure drop in the filter bag reaches 800Pa, through Electromagnetically controlled rapping device vibrates to make the filter layer material on the filter bag fall off and enter the ash hopper;

f. Collect the filter layer material in the ash hopper, and add 5 times the quality of water to dissolve the manganese sulfate and manganese nitrate in the filter layer material to obtain the solid-liquid mixture I, and carry out solid-liquid separation to the solid-liquid mixture I Finally, a solid I composed of manganese oxides and soot and a liquid I composed of manganese sulfate and manganese nitrate dissolved in water are obtained;

g. Neutralize the liquid I with ammonia water to the pH value of the liquid in the range of 8 to 9, aerate and oxygenate the divalent manganese ions into tetravalent manganese ions to obtain the solid-liquid mixture II, and perform solid-liquid separation on the solid-liquid mixture II , to obtain a solid II composed of manganese oxides and a liquid II rich in ammonium sulfate and ammonium nitrate;

h. Mix solid I with solid II to obtain recovered manganese oxide slurry, store it in the manganese oxide silo, use the recovered manganese oxide slurry as the manganese oxide used in step c, and spray it into the coal-fired coal from the connecting pipeline Recycled in flue gas.

i. The solid I obtained after the filter layer material is dissolved in water is continuously circulated, resulting in the accumulation of soot components in the solid I. When the soot content in the solid I is higher than 85%, the soot in the solid I is removed as follows, and then recycled Use: use solid I as manganese oxide until step c (the amount of dosing solid I is according to the molar ratio of tetravalent manganese and sulfur dioxide in coal-fired flue gas is 0.9:1), do not add ammonia gas in step d Step, make the sulfur dioxide and nitrogen oxides in the coal-fired flue gas completely reduce the tetravalent manganese ions in the solid I to divalent manganese ions, generate manganese sulfate and manganese nitrate, and the manganese sulfate, manganese nitrate and soot are accompanied by the coal-fired flue gas It enters the filter bag of the bag filter and is trapped on the surface of the filter bag to form a filter layer; after the automatic detection device detects that the concentration of sulfur dioxide in the exhaust gas exceeds the emission requirements, the electromagnetically controlled rapping device makes the filter on the filter bag The layer material falls off and enters the ash hopper, dissolves the material in the ash hopper with water according to the ratio of solid-liquid mass ratio 1:5 to extract the manganese sulfate and manganese nitrate, and separates the solid and liquid to obtain solid and liquid. The obtained liquid is made of manganese sulfate and nitric acid. Manganese is dissolved in water to form a liquid, and the obtained solid is smoke dust. The solid is discarded directly as waste, and the liquid I is neutralized with ammonia water to a pH value of 8-9, and aerated with oxygen to oxidize divalent manganese ions to tetravalent manganese. Manganese oxides are recovered by liquid separation to obtain solids and liquids, and the solids are stored in the silo for later use. After one cycle of manganese oxide materials is completed, the accumulation of smoke and dust in the materials is basically eliminated, and then the operation is resumed to steps c-h.

According to the method of this embodiment, the desulfurization efficiency can be greater than 90%, and the denitrification efficiency can be greater than 85%.

Example 2

a. Coal-fired flue gas passes through the electrostatic precipitator to remove most of the dust, and the sulfur content in the flue gas is about 550PPm;

b. Adjust the temperature of coal-fired flue gas after electrostatic precipitator to keep it stable at 150-160°C;

c. Inject natural high-grade manganese oxide ore powder into the connecting pipe between the electrostatic precipitator and the bag filter, so that the manganese oxide can quickly react with the sulfur dioxide in the coal-fired flue gas, and remove large amounts of coal-fired flue gas. Part of the sulfur dioxide forms manganese sulfate, and reacts with part of the nitrogen oxides in the coal-fired flue gas, and the nitrogen oxides are removed to form manganese nitrate; manganese sulfate, manganese nitrate, unreacted manganese oxides and soot enter with the coal-fired flue gas In the filter bag of the bag filter, it is trapped on the surface of the filter bag to form a filter layer, and the purified flue gas is discharged through the filter bag; the unreacted manganese oxide in the filter layer continues to interact with the residual sulfur dioxide in the coal-fired flue gas Reaction; the mass ratio of the added manganese oxide to the sulfur dioxide in the coal-fired flue gas delivered to the connecting pipeline is 5:1;

d. Spray ammonia gas into the coal-fired flue gas of the bag filter, and the unreacted manganese oxide in the filter layer on the surface of the filter bag acts as a selective catalytic reduction catalyst to play an efficient denitrification catalytic effect, so that the ammonia gas will burn coal The remaining nitrogen oxides in the flue gas are reduced to nitrogen; the mass ratio of the injected ammonia gas to the nitrogen oxides in the coal-fired flue gas entering the filter bag is 1:1.5;

e. As the thickness of the filter layer on the surface of the filter bag (composed of soot, manganese oxide and its desulfurization and depinning reaction products manganese sulfate and manganese nitrate) increases, the filter resistance of the filter bag increases. When the pressure drop in the filter bag reaches 900Pa, through Electromagnetically controlled rapping device vibrates to make the filter layer material on the filter bag fall off and enter the ash hopper;

f. Collect the filter layer material in the ash hopper, and add 8 times the quality of water to dissolve the manganese sulfate and manganese nitrate in the filter layer material to obtain the solid-liquid mixture I, and carry out solid-liquid separation to the solid-liquid mixture I Finally, a solid I composed of manganese oxides and soot and a liquid I composed of manganese sulfate and manganese nitrate dissolved in water are obtained;

g. Neutralize liquid I with ammonia water until the pH of the liquid is in the range of 8 to 9, then aerate and oxygenate divalent manganese ions to tetravalent manganese ions to obtain solid-liquid mixture II, and carry out solid-liquid mixture II for solid-liquid mixture II separation to obtain a solid II consisting of manganese oxides and a liquid II rich in ammonium sulfate and ammonium nitrate;

h. After mixing solid I and solid II, boil and oxidize at 450°C or in a rotary kiln for 30 minutes in an air atmosphere to obtain recovered manganese oxide powder; add the recovered manganese oxide powder into the manganese oxide silo, As the manganese oxide used in step c, it is injected into the coal-fired flue gas from the connecting pipeline for recycling.

J, the obtained solid I after the filter layer material is dissolved in water is continuously circulated, causing the soot component in the solid I to accumulate, and when the soot content in the solid I is higher than 85%, remove the soot in the solid I in the same manner as in Example 1 , and then recycled.

According to the method of this embodiment, the desulfurization efficiency can be greater than 90%, and the denitrification efficiency can be greater than 90%.

Claims (10)

1. A method for synchronous desulfurization, denitrification and dust removal in a bag filter, characterized in that: Using the bag filter as the reaction device, the coal-fired flue gas after electrostatic precipitating is introduced into the bag filter through the connecting pipe, and manganese oxide is injected into the connecting pipe to make the manganese oxide remove the coal-fired flue gas. Most of the sulfur dioxide in the sulfur dioxide will form manganese sulfate, and some nitrogen oxides will be removed to form manganese nitrate; A filter layer is formed on the surface of the filter bag of the bag filter; the unreacted manganese oxide in the filter layer continues to react with the residual sulfur dioxide in the coal-fired flue gas; ammonia is injected into the coal-fired flue gas entering the bag filter Gas, under the catalysis of the unreacted manganese oxide in the filter layer, the ammonia gas reduces the remaining nitrogen oxides in the coal-fired flue gas to nitrogen; As the thickness of the filter layer increases, the filter resistance of the filter bag increases. When the pressure drop in the filter bag reaches 800-900Pa, the filter layer is removed by electromagnetic rapping or pulse blowing and the filter layer material is collected. After the filter layer material is recovered Regeneration is carried out and the obtained manganese oxides are recycled to the injection connection pipeline. 2. The method for synchronous desulfurization, denitrification and dust removal in the bag filter according to claim 1, characterized in that: The mass ratio of the manganese oxide injected into the connecting pipeline to the sulfur dioxide in the coal-fired flue gas delivered to the connecting pipeline is 2:1-5:1. 3. The method for synchronous desulfurization, denitrification and dust removal in the bag filter according to claim 1, characterized in that: The mass ratio of the ammonia gas injected into the coal-fired flue gas of the bag filter to the nitrogen oxides in the coal-fired flue gas entering the bag filter is 1:1 to 1:1.15. 4. The method for synchronous desulfurization, denitrification and dust removal in the bag filter according to claim 1, characterized in that: Before the coal-fired flue gas enters the bag filter, adjust the temperature of the coal-fired flue gas to stabilize the temperature of the coal-fired flue gas in the bag filter at 150-220°C to ensure the temperature requirements of the out-of-stock reaction and the safe use of the filter bag. 5. The method for synchronous desulfurization, denitrification and dust removal in the bag filter according to claim 1, characterized in that: The method of regenerating the filter layer material to obtain manganese oxide is: adding 3 to 10 times the mass of water to the filter layer material to obtain a solid-liquid mixture I, and separating the solid-liquid mixture I to obtain the manganese oxide Solid I composed of smoke and dust and liquid I composed of manganese sulfate and manganese nitrate dissolved in water; Neutralize the liquid I with ammonia water until the pH value is in the range of 8-9, then aerate and oxygenate the divalent manganese ions to be oxidized to tetravalent manganese ions to obtain the solid-liquid mixture II, and perform solid-liquid separation on the solid-liquid mixture II , to obtain a solid II composed of manganese oxides and a liquid II rich in ammonium sulfate and ammonium nitrate; Mix solid I and solid II to obtain recycled manganese oxide slurry, or mix solid I and solid II and then boil and oxidize at 300-500°C or rotary kiln for 10-40 minutes in an air atmosphere to obtain recycled manganese oxide Powder; use the recovered manganese oxide slurry or the recovered manganese oxide powder as the manganese oxide, and inject it into the coal smoke from the connecting pipeline connected between the electrostatic precipitator and the bag filter Air recycling. 6. According to the method of synchronous desulfurization, denitrification and dust removal in the bag filter according to patent claim 1, it is characterized in that the following steps are taken: a. First pass the coal-fired flue gas through the electrostatic precipitator to remove most of the dust. When burning high-sulfur pulverized coal so that the sulfur content in the coal-fired flue gas is higher than 800PPm, first add high-sulfur pulverized coal to the high-sulfur pulverized coal 1-3% by mass of limestone powder for re-burning; b. Before introducing the coal-fired flue gas after electrostatic precipitator into the bag filter through the connecting pipe, adjust the temperature of the coal-fired flue gas so that the temperature of the coal-fired flue gas in the bag filter is stable at 150-220°C to ensure out-of-stock The temperature requirements of the reaction and the safe use requirements of the filter bag; c. Inject manganese oxide into the coal-fired flue gas in the connecting pipe between the electrostatic precipitator and the bag filter, so that the manganese oxide can quickly react with the sulfur dioxide in the coal-fired flue gas, and remove the coal-fired flue gas Most of the sulfur dioxide in the sulfur dioxide forms manganese sulfate, and reacts with part of the nitrogen oxides in the coal-fired flue gas, and the nitrogen oxides are removed to form manganese nitrate; manganese sulfate, manganese nitrate, unreacted manganese oxides and smoke The gas enters the bag filter and is trapped on the surface of the filter bag of the bag filter to form a filter layer; the unreacted manganese oxide in the filter layer continues to react with the residual sulfur dioxide in the coal-fired flue gas; the added The mass ratio of the manganese oxide to the sulfur dioxide in the coal-fired flue gas transported to the connecting pipeline is 2:1 to 5:1; d. Spray ammonia gas into the coal-fired flue gas entering the bag filter, and the unreacted manganese oxide in the filter layer on the surface of the filter bag is used as a selective catalytic reduction catalyst to exert high-efficiency denitrification in the temperature range of 150°C to 220°C Catalysis, so that ammonia can reduce the remaining nitrogen oxides in the coal-fired flue gas to nitrogen; The mass ratio of oxides is 1:1～1:1.15; e. As the thickness of the filter layer on the surface of the filter bag increases, the filter resistance of the filter bag increases. When the pressure drop in the filter bag reaches 800-900Pa, the filter bag is vibrated by electromagnetically controlled rapping device or pulsating blowing. Layer material falls off and enters the ash hopper; f. Collect the filter layer material in the ash hopper, and add 3 to 10 times the quality of water to dissolve the manganese sulfate and manganese nitrate in the filter layer material to obtain the solid-liquid mixture I, and solid-liquid mixture I is solidified. After liquid separation, a solid I composed of manganese oxides and soot and a liquid I composed of manganese sulfate and manganese nitrate dissolved in water are obtained; g. Neutralize liquid I with ammonia water until the pH of the liquid is in the range of 8 to 9, then aerate and oxygenate divalent manganese ions to tetravalent manganese ions to obtain solid-liquid mixture II, and carry out solid-liquid mixture II for solid-liquid mixture II Separation to obtain a solid II consisting of manganese oxides and a liquid II rich in ammonium sulfate and ammonium nitrate; h. Mix solid I and solid II to obtain recovered manganese oxide slurry, or mix solid I and solid II and boil and oxidize at 300-500°C or rotary kiln for 10-40 minutes in an air atmosphere to obtain recovered manganese Oxide powder: using the recovered manganese oxide slurry or the recovered manganese oxide powder as the manganese oxide used in step c, spraying it into the coal-fired flue gas from the connecting pipeline for recycling. 7. The method for synchronous desulfurization, denitrification and dust removal in a bag filter according to claim 5 or 6, characterized in that: solid ammonium sulfate and ammonium nitrate are obtained by concentrating and crystallizing the liquid II produced during the regeneration process of the filter material. 8. The method for synchronous desulfurization, denitrification and dust removal in the bag filter according to patent claim 5 or 6, characterized in that: the solid I obtained after the filter layer material is dissolved in water is continuously circulated, resulting in the formation of smoke and dust in the solid I Accumulation, the proportion of soot increased, when the soot content in the solid I was higher than 90%, the solid I was directly discarded by 5-20%, and in the remaining solid I, the new manganese oxide of the same quality as the discarded part was replenished, and then It can be recycled after being mixed with solid II. 9. According to the method of synchronous desulfurization, denitrification and dust removal in the bag filter according to patent claim 5 or 6, it is characterized in that: the solid I obtained after the filter layer material is dissolved in water is continuously circulated, resulting in the accumulation of soot components in the solid I , when the soot content in the solid I is higher than 85%, the soot in the solid I is removed as follows, and then recycled: the solid I is injected into the connecting pipe as manganese oxide, so that the sulfur dioxide and Nitrogen oxides completely reduce the tetravalent manganese ions in the solid I to divalent manganese ions to generate manganese sulfate and manganese nitrate. Manganese sulfate, manganese nitrate and soot enter the filter bag of the bag filter along with the coal-fired flue gas, and It is trapped on the surface of the filter bag to form a filter layer; the filter layer is removed by electromagnetic rapping or pulse blowing and the filter layer material is collected, and the filter layer material is dissolved in water to obtain a solid-liquid mixture. After solid-liquid separation, the obtained liquid It is a liquid composed of manganese sulfate and manganese nitrate dissolved in water, and the obtained solid is soot. Recover the liquid composed of manganese sulfate and manganese nitrate dissolved in water and regenerate it into manganese oxide. Discard the soot and remove the soot in the solid I in this way. After the soot, it can be recycled again; the amount of solid I to be added is according to the molar ratio of tetravalent manganese to sulfur dioxide in the coal-fired flue gas, which is 0.9:1-1:1. 10. According to the method of synchronous desulfurization, denitrification and dust removal in the bag filter according to patent claims 1 and 2, it is characterized in that: the initially used manganese oxide is manganese concretion powder, natural high-grade manganese oxide ore powder, industrial Manganese dioxide powder.