CN112426861A - Efficient desulfurization and denitrification system and method - Google Patents

Efficient desulfurization and denitrification system and method Download PDF

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CN112426861A
CN112426861A CN202011254565.4A CN202011254565A CN112426861A CN 112426861 A CN112426861 A CN 112426861A CN 202011254565 A CN202011254565 A CN 202011254565A CN 112426861 A CN112426861 A CN 112426861A
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flue gas
tower
desulfurization
reduction
denitration
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田富军
林治成
王灿
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Fujian Sanbao Steel Co Ltd
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Fujian Sanbao Steel Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/75—Multi-step processes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/343—Heat recovery
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86—Catalytic processes
    • B01D53/8603—Removing sulfur compounds
    • B01D53/8609—Sulfur oxides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86—Catalytic processes
    • B01D53/8621—Removing nitrogen compounds
    • B01D53/8625—Nitrogen oxides
    • B01D53/8628—Processes characterised by a specific catalyst
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2251/00—Reactants
    • B01D2251/20—Reductants
    • B01D2251/206—Ammonium compounds
    • B01D2251/2062—Ammonia
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/20—Metals or compounds thereof
    • B01D2255/207—Transition metals
    • B01D2255/20723—Vanadium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/20—Metals or compounds thereof
    • B01D2255/207—Transition metals
    • B01D2255/20769—Molybdenum
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/20—Metals or compounds thereof
    • B01D2255/209—Other metals
    • B01D2255/2092—Aluminium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/30—Silica
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/50—Zeolites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2258/00—Sources of waste gases
    • B01D2258/02—Other waste gases
    • B01D2258/0283—Flue gases

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  • General Chemical & Material Sciences (AREA)
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Abstract

The desulfurization and denitrification system of the invention is provided with and connected SO in sequence at the downstream side of the combustion boiler3The device comprises a reduction catalyst bed, a denitration tower, a heater, a dust remover, a heat exchanger for heat exchange, a wet desulfurization tower and a flue gas tower. The heat exchanger is used for exchanging heat, recovering and storing heat energy; SO (SO)3The reduction catalyst bed is disposed on the downstream side of the combustion boiler and on the upstream side of the denitration tower. The desulfurization and denitrification method removes the SO with strong corrosivity at the upstream side3The gas reduces the corrosion of the flue gas to the equipment; meanwhile, the heat exchanger is used for cooling the flue gas, thereby improving the SO removal by wet desulphurization2The efficiency of (c).

Description

Efficient desulfurization and denitrification system and method
Technical Field
The invention relates to a system and a method for desulfurization and denitrification, in particular to a system and a method for simultaneously removing nitric oxide and sulfur oxide in flue gas.
Background
The boiler flue gas contains a large amount of sulfur and nitrogen oxides if directly dischargedTo the atmosphere, serious atmospheric pollution is formed. In the prior art, the methods mainly adopted for reducing the sulfide in the flue gas include dry flue gas desulfurization, semi-dry flue gas desulfurization and wet flue gas desulfurization, and the basic principle of the methods is to ensure that SO in the flue gas is generated2And carrying out neutralization reaction with alkali. The wet desulfurization technique is to make SO in the flue gas2Reacting with alkaline solution to remove sulfide in flue gas. The wet desulphurization technology has high desulphurization efficiency and high utilization rate of the absorbent. Denitration technology generally utilizes a catalytic reduction method, and utilizes a reducing agent to reduce NOx into N2And then discharging.
CN103611398A discloses an efficient sea water flue gas desulfurization and denitration method, belongs to the field of flue gas desulfurization and denitration, and comprises a sea water desulfurization absorption tower and the following steps: before the flue gas enters the seawater desulfurization absorption tower, NO is oxidized into NO capable of being dissolved in seawater by adopting NO oxidant2While part of SO2By oxidation to SO3Then using SO3Pre-removing agent bicarbonate pre-removing SO3And part of the nitrogen oxides and SO2In the seawater desulfurization absorption tower, the flue gas is washed by seawater, and unreacted NO oxidant and SO are removed3Pre-remover and SO3The by-products in the pre-removing process are dissolved in the washed seawater, and the seawater subjected to desulfurization and denitrification is discharged into the sea after the water quality is recovered to reach the standard by a seawater recovery system. The invention can realize desulfurization and denitrification at the same time and has higher desulfurization and denitrification efficiency; the method has the characteristics of integration of flue gas desulfurization and denitration, low investment and operation cost, stable operation of a device/system, high safety and reliability and the like.
CN110762520A relates to a method for efficiently desulfurizing and denitrating coal in combustion, relates to the technical field of clean combustion, and comprises the following steps: coal is sprayed into the hearth from a coal inlet pipe of the circulating fluidized bed boiler and is combusted in the hearth, a desulfurizer is sprayed into the hearth, and a denitrifier is sprayed into a discharge port of the hearth and is positioned at an inlet of the cyclone separator. Removal of SO from flue gas by means of desulphurizing and denitrating agents3NOx, reducing SO in the exhaust gas2NOx amount to meet the ultra-low emission concentration lower than the national regulationThe standard of (2).
CN105642098A discloses a desulfurization and denitrification method, and the adopted system comprises a tower body, wherein the lower part of the tower body is provided with a flue gas inlet, the lower part corresponding to the flue gas inlet is arranged in the tower body and is provided with an oxidation section, and the upper part corresponding to the flue gas inlet is arranged in the tower body and is sequentially provided with a concentration section, an absorption section, a purification washing section and a demisting section from bottom to top. The desulfurization and denitrification system is ingenious and reasonable in structural design, effectively solves the problem of high operation cost, is stable in process, integrally operates in absorption and concentration crystallization, does not discharge any waste liquid, limits ammonia escape discharge, and thoroughly solves the problems of ammonia escape and aerosol. The desulfurization and denitrification method provided by the invention has simple process steps, realizes desulfurization and denitrification effects, has the characteristics of high desulfurization and denitrification efficiency, energy conservation and environmental protection, low cost and safe and stable operation, can change waste into valuable, and is a key direction for environmental-friendly desulfurization development in the future.
The system and the method for desulfurization and denitrification in the prior art are used for treating SO in flue gas3Lack of effective removal means often treats all sulfur oxides and nitrogen oxides in the same process, which results in inefficient removal of harmful gases, especially SO3Has more residues, serious air pollution and strong corrosive SO3The flue gas also causes catalyst failure on the downstream side and equipment corrosion.
Disclosure of Invention
The invention develops a desulfurization and denitrification system and a desulfurization and denitrification method, which can efficiently remove nitrogen oxides (NOx) and Sulfur Oxides (SO) in discharged flue gas3And SO2). To achieve the above effects, the inventor obtains the technical means of the present invention by designing as follows:
by passing SO in the system of the invention3The reduction catalyst and the denitration catalyst are connected in series (arranged in series), preferably, the sulfur oxide and the nitrogen oxide in the raw material flue gas are removed by using the catalyst, and characterized in that the sulfur oxide removing step is provided upstreamThe side and the nitrogen oxide removing process are arranged at the downstream side, and the two processes are arranged in the flow direction of the flue gas in the system sequentially, immediately and serially.
In the present invention, ammonia is used as a reducing agent to treat nitrogen oxides and sulfur oxides. Preferably, in SO3After reduction, SO3NH at the outlet of the downstream side of the reduction catalyst bed3Concentration relative to SO3The amount of (B) is not less than 1.
In the flue gas treatment method and the desulfurization and denitrification system, the flue gas contains nitrogen oxide (NOx) and sulfur trioxide (SO)3) NOx and SO3Can be efficiently removed simultaneously by the reduction reaction. Thus, the system according to the invention is treated in flue gases, due to the upstream side SO in the system3Has been removed, the denitration catalyst in the denitration tower on the downstream side is not easily poisoned or failed, so that the system for desulfurization and denitration of the present invention has advantages such as the whole system is simple and easy to use, easy to maintain and long in service life.
In the flue gas treatment method of the present invention, SO3The reduction process is set prior to the denitration reaction at the upstream side, and the denitration process is performed on the flue gas containing nitrogen oxides at the downstream side in the flow direction of the flue gas. In SO3During the first stage of the reduction, ammonia NH3As a reducing agent, injection is added by an external ammonia source. Wherein NH3During the addition, ammonia should be added to the flue gas, NH3The molar ratio of ammonia to nitrogen oxides (NOx) is preferably 1.5 or more. Due to NH3SO when added to flue gas3When the reduction reaction occurs, SO that the process step is SO3In the reduction step, the concentration of ammonia is relatively high. In SO3In the course of the reduction, SO3Reducing under the action of a catalyst. As described earlier, by using NH3As reducing agent, SO3Reduction reaction (SO)3Is converted into SO in the presence of ammonia and oxygen-enriched air2). Thus, in the preceding stage, SO3The reduction reaction is completed. In SO3After the reduction process is completed, it is preferableIn SO3NH at the downstream outlet of the reduction catalyst bed3The concentration is controlled to be not less than 1 with respect to the NOx content. Because if NH is present3The concentration of (b) is too low, and the effect of removing nitrogen oxides is deteriorated in the denitration process at the downstream side because the reducing agent is insufficient. In the subsequent nitrogen oxide removal step in the present system, nitrogen oxides are reduced to N by an ammonia reducing agent in the presence of a denitration catalyst2。
In the present system, when SO3And after the NOx two-stage reduction process is finished, if residual excessive ammonia exists, oxidizing the ammonia into N in the presence of oxygen-enriched air2. In the present invention, SO3The reduction process is generally disposed on the upstream side of the denitration process. Therefore, it is necessary to control the concentration at SO3The subsequent stage of the reduction process and the previous stage of the denitration process add a predetermined amount of ammonia according to the reaction need. NOx and SO after denitration treatment of exhaust gas3Both are reduced and removed, and NH is added3Is also removed. In the present invention, NOx and SO of the flue gas3Is reduced and removed, thereby eliminating the highly corrosive SO3Gases, i.e. flue gases, passing through downstream equipment, e.g. dust separators and wet desulphurizers, i.e. flue gases containing SO2Gas (corrosive to equipment versus SO)3Much weaker), the corrosive effects on the equipment are also greatly reduced.
In the present invention, the wet desulfurizer is used for the sulfur-containing gas2Before wet desulfurization of flue gas, preferably, the flue gas is cooled by using a heat exchanger SO as to remove SO by wet desulfurization2The efficiency is higher (when the high-temperature gas is mixed with the sprayed desulfurizer solution, water vapor and smoke are easily generated, and the reaction is influenced). Preferably, after wet desulphurization, the heat recovered by the previous heat exchange storage is reused for heating the flue gas before being discharged into the atmosphere, so that the flue gas is further purified, the fluid kinetic energy of the flue gas in the chimney is increased, the flue gas is discharged into the atmosphere more smoothly, and the blockage of the fluid in the chimney is reduced.
Specifically, the scheme provided by the invention is as follows:
a high-efficiency desulfurization and denitrification system, which is characterized in that,
a SO3 reduction catalyst bed, a denitration tower, a heater, a dust remover, a heat exchanger for heat exchange and a wet desulfurization tower are sequentially arranged on the downstream side of the combustion boiler;
the upstream side of the combustion boiler is provided with a connecting inlet of raw material smoke and oxygen-enriched air;
the SO3 reduction catalyst bed is arranged at the downstream side of the combustion boiler and the upstream side of the denitration tower, and the upstream side of the SO3 reduction catalyst bed is also connected with an ammonia storage tank which injects ammonia into the SO3 reduction catalyst bed;
the heat exchanger is used for exchanging heat, recovering and storing heat energy, the upper and lower streams of the heat exchanger are connected with the dust remover, the heat exchanger and the wet desulfurization tower in sequence, and the outlet of the wet desulfurization tower is connected with the heat exchanger and the flue gas tower in sequence.
Preferably, the ammonia storage tank is connected with SO3The connection of the reduction catalyst bed may use a plurality of injection pipes or a plurality of nozzles.
Preferably, the plurality of nozzles are arranged in parallel perpendicular to the gas flow.
Preferably, the SO3In the reduction catalyst bed, a catalyst in which Ru is supported as an active metal on a carrier which is at least one selected from the group consisting of titania, alumina, zirconia, silica and zeolite or a combination thereof is placed.
Preferably, the catalyst is honeycomb-shaped.
Preferably, a denitration catalyst is placed in the denitration tower, and the denitration catalyst is a catalyst containing at least one active metal selected from Mo and V supported on a carrier.
Preferably, the support is selected from Al2O3、SiO2At least one of a metal silicate and a zeolite.
A method for efficient desulfurization and denitrification, comprising the following steps:
1) feeding raw materials: injecting raw material flue gas and oxygen-enriched air into a combustion boiler;
2)SO3reduction and catalysis: introduction of ammoniaReducing agent at SO3Reduction of SO in flue gas in catalyst bed3Reduction to SO2；
3) Denitration reduction catalysis: SO (SO)3The reduced flue gas enters a denitration tower, and NOx in the flue gas is reduced;
4) heating and dedusting: heating the denitrated flue gas by a heater, and introducing the denitrated flue gas into a dust remover to capture large-particle impurity particles in the flue gas;
5) heat exchange and desulfurization: cooling the dedusted flue gas by a heat exchanger, feeding the cooled flue gas into a wet-type desulfurizing tower, and collecting SO in the flue gas2Is removed;
6) heat exchange and exhaust: removal of SO2The flue gas is heated by a heat exchanger and then discharged out of the flue gas tower.
Preferably, in SO3Before the reduced flue gas enters the denitration tower, coke is used for treating the flue gas.
Preferably, NH3In the course of addition, NH3The molar ratio to nitrogen oxides (NOx) is preferably 1.5 or more.
Preferably, in SO3NH at the downstream outlet of the reduction catalyst bed3The concentration is controlled to be not less than 1 with respect to the NOx content.
The technical effects obtained by the invention comprise:
the invention removes the SO with strong corrosiveness at the upstream side of the system3The gas reduces the corrosion of the flue gas to the equipment; meanwhile, in the invention, the flue gas is cooled by using the heat exchanger, thereby improving the SO removal by wet desulphurization2The efficiency of (c). After wet desulphurization, the heat recovered by the previous heat exchange storage is used for heating the flue gas again, so that the flue gas is further purified, and meanwhile, the kinetic energy of the fluid of the flue gas in the chimney is increased, the flue gas is discharged to the atmosphere more smoothly, and the blockage of the fluid in the chimney is reduced.
Description of the drawings 1
FIG. 1 is a schematic view of a desulfurization and denitrification system and a process flow of the present invention.
The reference numbers in the drawings are as follows: 1. a combustion boiler; 2. SO (SO)3Reducing the catalyst bed; 3. an ammonia storage tank, 4, a denitration tower; 5. a heater; 6. removing deviceA dust collector; 7. a heat exchanger; 8. a wet desulfurization tower; 9. a flue gas tower.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar modules or modules having the same or similar functionality throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.
In the desulfurization and denitrification system of the present invention, referring to fig. 1, SO is connected in sequence to the downstream side of a combustion boiler 13A reduction catalyst bed 2, a denitration tower 4, a heater 5 as a heating means, a dust remover 6, and a heat exchanger 7 for heat exchange. In addition, the heat exchanger 7 can regulate and recover heat energy, and the upper and lower streams are connected with the dust remover 6, the heat exchanger 7, the wet-type desulfurization tower 8 and the flue gas tower 9 in sequence; SO (SO)3The reduction catalyst bed 2 is disposed on the downstream side of the combustion boiler 1 and on the upstream side of the denitration tower 3. In SO3An ammonia storage tank 3 is connected upstream of the reduction catalyst bed 2 and can inject ammonia as a reducing agent. Preferably, for example, the ammonia storage tank 3 is connected with SO3The connection of the reduction catalyst bed 2 may use a plurality of injection pipes or a plurality of nozzles. As a method for injecting ammonia, liquid ammonia may be vaporized, and the vaporized reducing agent is injected by feeding air, inert gas, water vapor, or the like into the pipe. Preferably, to ensure uniform flow of ammonia to SO3Uniformity of the reduction catalyst bed and mixing of the gases, multiple nozzles are arranged in parallel perpendicular to the gas flow. Preferably, SO is used in the system3In the reduction catalyst bed 2, it is possible to use a catalyst having SO3Any catalyst that is functional for reduction. Preferably, Ru may be selected as the catalyst with the active metal supported on the carrier. For SO3The kind of the carrier of the reduction catalyst is not particularly limited, and preferably, it is selected from at least one of titania, silica and zeolite or a combination thereof. Further, preferably, SO is added as required3The reduction catalyst may contain at least one metal selected from W and V in the carrierAs a cocatalyst. SO (SO)3The shape of the reduction catalyst is not particularly limited. Preferably, a honeycomb catalyst or a catalyst formed by filling particles, or the like can be used.
Preferably, as the denitration catalyst used in the denitration column 4 of this system, a catalyst in which at least one kind selected from Mo and V is supported as an active metal on a carrier is used. Preferably, the catalyst comprises at least one active metal selected from Pd, Ir, Cu, Co, Ag, Mn, Ni, and Zn in a carrier of the catalyst. Preferably, the carrier may be selected from Al2O3、SiO2At least one of a metal silicate and a zeolite. Preferably, the shape of the nitration catalyst is not particularly limited. For example, a honeycomb catalyst, a catalyst formed by filling particles, or the like may be used.
Preferably, the dust collector 6 is capable of collecting dust in the flue gas and then guiding the dust-collected flue gas into the heat exchanger 7.
Preferably, a heat exchanger 7 for recovering heat energy and a wet desulfurization tower 8 are provided downstream of the dust separator 6. Preferably, the wet desulfurization tower 7 is not particularly limited. For example, a wet desulfurization absorption tower generally used for a flue can perform gas treatment, and preferably, a desulfurizing agent is provided for use. Preferably, a common wet desulfurizing agent is used as the desulfurizing agent, and an aqueous solution of an alkali absorbent such as calcium oxide, calcium hydroxide, sodium carbonate, or sodium hydroxide is selected as the wet absorbing desulfurizing agent.
Preferably, in the wet desulfurization absorption tower 8, the sulfur-containing gas is introduced from the bottom of the tower, and the introduced gas flows along the tower from bottom to top and reacts with the desulfurizing agent sprayed from top to bottom from the top of the tower to perform desulfurization.
Preferably, in the system, the heat exchanger 7 is provided downstream of the dust separator 6, and absorbs the high-temperature gas discharged from the dust separator 6, and after heat exchange, the cooled low-temperature gas (flue gas to be desulfurized) is discharged from the heat exchanger 7, and is introduced into the wet desulfurization tower 8 to be subjected to wet desulfurization. Meanwhile, preferably, the heat energy after the first heat exchange can be recycled and stored in the heat exchanger.
Preferably, in the system, the heat exchanger 7 is disposed downstream of the wet desulfurization tower 8 and connected again, and the heated gas is discharged to the air through the flue gas tower 9. After passing through the apparatus of the invention, the gas to be discharged is reheated and burned, in particular in the heat exchanger 7, wherein the heat energy previously recovered in the heat exchanger 7 is used for heating the desulfurized gas. Preferably, the heat energy is exchanged by using a heat medium as a medium, such as a gas-gas direct heat exchange. Preferably, the heat exchanger 7 comprises a first inlet, a first outlet and a second inlet, a second outlet, wherein the first inlet and the first outlet are distributed at the top of the heat exchanger and the second inlet and the second outlet are distributed at the bottom. Wherein the first inlet is connected with the dust remover 6, the first outlet is connected with the inlet of the wet-type desulfurization tower, the second inlet is connected with the outlet of the wet-type desulfurization tower, and the second outlet is connected with the flue gas tower.
Preferably, the raw flue gas is selected from gases discharged from steel plants, petrochemical plants and the like and used for combustion or heating furnaces, and preferably, the gases include carbon dioxide, oxygen, sulfur oxides, nitrogen oxides, smoke, water, simple substances or free elements such as sulfur, phosphorus, arsenic, hydrogen and the like. Therefore, raw material flue gas and oxygen-enriched air firstly pass through the combustion boiler 1, firstly, some free simple substance impurities are removed through pretreatment, secondly, the flue gas temperature is reasonably increased, and the subsequent reaction activity is improved.
If SO may be present in the flue gas during the desulfurization and denitrification processes2By oxidation of (2), SO produced3Will be further increased. Preferably, another stage of reduction process (e.g., reduction of SO using coke) may be added on the upstream side before entering the denitration tower3) Effective removal of SO3。
DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION
The method for performing desulfurization and denitrification on flue gas by using the system shown in FIG. 1 comprises the following specific steps:
1) feeding raw materials: injecting raw material flue gas and oxygen-enriched air into a combustion boiler; wherein the raw material smoke composition is
3000ppm Sulfur oxides (including 70)0ppm SO3) 1000ppm NOx, 100ppm NH3，10％H2O，15％COxThe balance being essential impurities and N2。
2)SO3Reduction and catalysis: introducing ammonia as reductant in SO3Reduction of SO in flue gas in catalyst bed3Reduction to SO2(ii) a The temperature is selected to be suitable reaction temperature, is suitable for reduction reaction, and can be preferably selected to be 350-380 ℃; ammonia reducing agent is introduced to ensure NH3The molar ratio/NOx is 1.5; the catalyst was selected as a commercial supported honeycomb TiO2A powdered particulate catalyst comprising Ru on a carrier.
3) Denitration reduction catalysis: SO (SO)3The reduced flue gas enters a denitration tower, and NOx in the flue gas is reduced; commercial supported honeycomb Al is selected as denitration catalyst2O3A supported V-containing catalyst.
4) Heating and dedusting: heating the flue gas subjected to denitration and reduction by a heater, and introducing the flue gas into a dust remover to capture large-particle impurity particles in the flue gas; the dust collector is selected to be an electrostatic dust collector.
5) Heat exchange and desulfurization: cooling the dedusted flue gas by a heat exchanger, feeding the cooled flue gas into a wet-type desulfurizing tower, and collecting SO in the flue gas2Is removed; and cooling the flue gas to room temperature, and spraying a solution of sodium hydroxide with the concentration of 10% from top to bottom in the wet desulfurization tower.
6) Heat exchange and exhaust: SO (SO)2The flue gas after being removed is heated by a heat exchanger and then discharged out of the flue gas tower.
The system and method of the present example were subjected to changes in the contents of nitrogen oxides and sulfur oxides to evaluate the desulfurization and denitrification efficiency.
Wherein, SO3SO in flue gas discharged from reduction catalyst bed3The content is reduced to 120 ppm; the NOx content in the flue gas discharged by the denitration tower is reduced to 80 ppm; SO in the flue gas discharged from the outlet of the wet desulfurization tower2The content of (B) is 50 ppm; the final composition of the flue gas exiting the flue gas column was 170ppm sulfur oxides (including 120ppm SO)3) 75ppm NOx, 10ppm NH3The balance being H2O toAnd N2. Therefore, the desulfurization and denitrification system and the method can effectively remove NOx and oxysulfide in the flue gas, and the flue gas reaches the latest national flue gas emission standard.
In the description herein, references to the description of "one embodiment," "another embodiment," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.

Claims (10)

1. A high-efficiency desulfurization and denitrification system, which is characterized in that,
at the downstream side of the combustion boiler, a connection SO is sequentially arranged3The device comprises a reduction catalyst bed, a denitration tower, a heater, a dust remover, a heat exchanger for heat exchange and a wet desulfurization tower;
the upstream side of the combustion boiler is provided with a connecting inlet of raw material smoke and oxygen-enriched air;
the SO3The reduction catalyst bed is disposed on the downstream side of the combustion boiler and the upstream side of the denitration tower, SO3The upstream side of the reduction catalyst bed is also connected with an ammonia storage tank which injects ammonia into SO3Reducing the catalyst bed;
the heat exchanger is used for exchanging heat, recovering and storing heat energy, the upper and lower streams of the heat exchanger are connected with the dust remover, the heat exchanger and the wet desulfurization tower in sequence, and the outlet of the wet desulfurization tower is connected with the heat exchanger and the flue gas tower in sequence.
2. The system of claim 1, wherein the ammonia storage tank is connected with SO3The connection of the reduction catalyst bed may use a plurality of injection pipes or a plurality of nozzles.
3. The system of claim 2, wherein the plurality of nozzles are arranged in parallel perpendicular to the gas flow.
4. The system for efficient desulfurization and denitrification according to claim 1, wherein the SO is3In the reduction catalyst bed, a catalyst in which Ru is supported as an active metal on a carrier which is at least one selected from the group consisting of titania, silica and zeolite or a combination thereof is placed.
5. The system of claim 4, wherein the catalyst is honeycomb-shaped.
6. The system according to claim 1, wherein a denitration catalyst is placed in the denitration tower, and the denitration catalyst comprises a carrier on which at least one of Mo and V is supported as an active metal.
7. The system of claim 6, wherein the carrier is selected from Al2O3、SiO2At least one of a metal silicate and a zeolite.
8. A method for efficiently desulfurizing and denitrating, which comprises the following steps,
1) feeding raw material flue gas: injecting raw material flue gas and oxygen-enriched air into a combustion boiler;
2)SO3reduction and catalysis: adding ammonia reducing agent into SO3Reduction of SO in flue gas in catalyst bed3Reduction to SO2；
3) Denitration reduction catalysis: SO (SO)3The reduced flue gas enters a denitration tower, and NOx in the flue gas is reduced;
4) heating and dedusting: heating the flue gas subjected to denitration and reduction by a heater, and introducing the flue gas into a dust remover to capture large-particle impurity particles in the flue gas;
5) heat exchange and desulfurization: cooling the dedusted flue gas by a heat exchanger, feeding the cooled flue gas into a wet-type desulfurizing tower, and collecting SO in the flue gas2Is removed;
6) heat exchange and exhaust: SO (SO)2The flue gas after being removed is heated by a heat exchanger and then discharged out of the flue gas tower.
9. The method for desulfurization and denitrification with high efficiency as recited in claim 8, wherein NH in the step 2)3NH in the course of addition3The molar ratio of nitrogen oxides (NOx) is 1.5 or more.
10. The method of claim 8, wherein the SO is used as a carrier for desulfurization and denitrification with high efficiency3NH at the downstream outlet of the reduction catalyst bed3The concentration is controlled to be not less than 1 with respect to the NOx content.
CN202011254565.4A 2020-11-11 2020-11-11 Efficient desulfurization and denitrification system and method Pending CN112426861A (en)

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Citations (5)

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Publication number Priority date Publication date Assignee Title
US5554350A (en) * 1994-12-15 1996-09-10 Combustion Engineering, Inc. Air pollution control and heat recovery system and process for coal fired power plant
CN105444195A (en) * 2015-12-25 2016-03-30 中电投远达环保工程有限公司 Multi-pollutant synergistic treating method and system for coal-fired flue gas
CN105813714A (en) * 2014-11-07 2016-07-27 三菱重工业株式会社 Exhaust gas treatment method and denitrification/SO[3] reduction apparatus
CN107366926A (en) * 2017-07-19 2017-11-21 上海汉卓能源科技有限公司 A kind of flue gas for wet desulphurization takes off white system and method
CN110594770A (en) * 2019-10-30 2019-12-20 中国大唐集团科学技术研究院有限公司西北电力试验研究院 System and method for relieving blockage of air preheater by spraying ammonia in different regions

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5554350A (en) * 1994-12-15 1996-09-10 Combustion Engineering, Inc. Air pollution control and heat recovery system and process for coal fired power plant
CN105813714A (en) * 2014-11-07 2016-07-27 三菱重工业株式会社 Exhaust gas treatment method and denitrification/SO[3] reduction apparatus
CN105444195A (en) * 2015-12-25 2016-03-30 中电投远达环保工程有限公司 Multi-pollutant synergistic treating method and system for coal-fired flue gas
CN107366926A (en) * 2017-07-19 2017-11-21 上海汉卓能源科技有限公司 A kind of flue gas for wet desulphurization takes off white system and method
CN110594770A (en) * 2019-10-30 2019-12-20 中国大唐集团科学技术研究院有限公司西北电力试验研究院 System and method for relieving blockage of air preheater by spraying ammonia in different regions

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