CN112090254A - Fuel oil and gas boiler PNCR and low-temperature SCR combined denitration system and process - Google Patents

Fuel oil and gas boiler PNCR and low-temperature SCR combined denitration system and process Download PDF

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CN112090254A
CN112090254A CN202010983661.6A CN202010983661A CN112090254A CN 112090254 A CN112090254 A CN 112090254A CN 202010983661 A CN202010983661 A CN 202010983661A CN 112090254 A CN112090254 A CN 112090254A
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denitration
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安璐
李永光
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Beijing Huadian Guangda Environment 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
    • B01D53/46—Removing components of defined structure
    • B01D53/54—Nitrogen compounds
    • B01D53/56—Nitrogen 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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES 
    • F23J15/00—Arrangements of devices for treating smoke or fumes
    • F23J15/02—Arrangements of devices for treating smoke or fumes of purifiers, e.g. for removing noxious material
    • 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
    • B01D2258/00—Sources of waste gases
    • B01D2258/02—Other waste gases
    • B01D2258/0283—Flue gases
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES 
    • F23J2215/00—Preventing emissions
    • F23J2215/10—Nitrogen; Compounds thereof

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  • Environmental & Geological Engineering (AREA)
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Abstract

The invention provides a fuel oil and gas boiler PNCR and low-temperature SCR combined denitration system and a process, which comprise the following steps: the PNCR denitration system comprises a conveying fan, a denitration agent hopper, a screw feeder, a gas material ejector, a distribution device and a denitration agent spray gun, wherein the denitration agent hopper, the screw feeder, the gas material ejector and the distribution device are sequentially connected, the gas material ejector is also connected with the conveying fan, a material inlet of the denitration agent spray gun is connected with the conveying fan and the distribution device, and a material outlet of the denitration agent spray gun is connected with a fuel oil and gas boiler; the low-temperature SCR denitration system comprises an SCR reactor and a low-temperature denitration catalyst, wherein the SCR reactor is connected with a fuel oil and gas boiler, and the low-temperature denitration catalyst is arranged inside the SCR reactor. The invention has the beneficial effects that: the denitration system is simple and reliable in modification, small in occupied area, low in investment cost, high in denitration efficiency, low in ammonia escape and economical and practical, and has the synergistic effect of PNCR denitration and low-temperature SCR denitration.

Description

Fuel oil and gas boiler PNCR and low-temperature SCR combined denitration system and process
Technical Field
The invention relates to the technical field of environmental protection, in particular to a PNCR and low-temperature SCR combined denitration system and a process for a fuel oil and gas boiler.
Background
Nitrogen Oxides (NO)x) Is one of the main atmospheric pollutants discharged by oil and gas boilers. With the increasing emphasis on environmental protection in China, the emission standards of oil-gas boilers established in various places in recent years are more and more strict, and especially the emission limit value of newly-built boilers is generallyUltra low emission levels, i.e. NO, are requiredxThe discharge value is not more than 50mg/m3. The development of denitration technology suitable for oil-fired and gas-fired boilers has become a trend.
TABLE 1 emission standard of atmospheric pollutants of boilers in partial regions
Figure BDA0002688368930000011
The oil and gas fired boiler has the characteristics of large quantity, wide distribution and high treatment difficulty. Particularly, the oil-gas fired boiler for central heating is generally close to a urban resident concentration area and has the characteristics of small occupied space and high safety requirement; meanwhile, the influence of the fluctuation of the operation heating load requirement is large, and the load fluctuation is large in the early stage, the middle stage and the final stage of the heating period and day and night in one day, so that great challenges are formed on the safe, stable and reliable operation of the denitration facility.
At present, the flue gas denitration technology mainly comprises a low-nitrogen combustor, a selective non-catalytic reduction method (SNCR), a selective catalytic reduction method (SCR) and the like, but the application of the technologies to a fuel oil and gas boiler has certain limitations.
The low-nitrogen combustor is a novel combustor adopting low-nitrogen combustion technology. The low-nitrogen combustion technology comprises air staged combustion, fuel staged combustion, Flue Gas Recirculation (FGR), full-premixed surface combustion and the like, and the FGR technology is generally adopted at present. The low nitrogen modification mainly has the following problems: (1) the investment cost is high; (2) technical maturity problem: existing FGR low-nitrogen burners typically can be fired with NOxThe discharge concentration is controlled to be 50-80 mg/m3Only a small amount of imported products can realize ultra-low emission and are expensive; (3) the heat efficiency of the boiler is reduced: the thermal efficiency of the low-nitrogen modified boiler is reduced by 2-4%, and the rated natural gas consumption of the 1t/h (0.7MW) oil-gas fired boiler is about 80m3The natural gas amount is increased by 1.6-3.2 m after low-nitrogen modification3The operating cost rises along with the increase of the/h; (4) the problem of operation stability: after the FGR low-nitrogen combustor is reformed, the boiler has the condensate water separated from CO with high CO content, unstable combustion, flame surge and deflagration and recirculated flue gasInfluence the operation of the burner and the like.
The SNCR technology means that a denitration agent is used for selectively reacting with NO in smokexThe denitration technology generates nitrogen and water by reaction. SNCR is simple and reliable, and has low investment and operation cost, thus being widely applied. However, SNCR has the following problems: (1) the denitration efficiency is low: the denitration efficiency of SNCR is greatly influenced by factors such as flue gas temperature, flow field condition, residence time and the like, is generally 20-30% when used for an oil-gas boiler, and is difficult to realize NO only by means of SNCRxUltra-low emission; (2) high ammonia escape: SNCR denitration ammonia has high escape, is easy to cause secondary pollution, and can cause corrosion to downstream equipment; (3) influence on the thermal efficiency of the boiler: the reducing agent adopted by the SNCR is ammonia water or urea, and the reducing agent needs to be diluted into 5% ammonia water or 10% urea solution before being sprayed into the boiler, so that a large amount of water is sprayed into flue gas; the heat absorption of water evaporation can affect the thermal efficiency of the boiler; (4) reducing agent selection problem: the ammonia water has high risk in the transportation and storage process and cannot be used in a resident concentration area; the urea denitration energy consumption is high, and the equipment corrosion and blockage can be caused when the decomposition is incomplete.
The SCR technology is to selectively react with NO in the flue gas by using a denitration agent under the action of a denitration catalystxThe denitration technology generates nitrogen and water by reaction. Due to the catalytic action of the denitration catalyst, compared with SNCR, SCR has the advantages of high denitration efficiency (up to more than 90%), low ammonia escape, flexible and various arrangement modes and the like. According to different application temperatures of denitration catalysts, the SCR technology can be divided into medium-temperature SCR (280-420 ℃) and low-temperature SCR (140-280 ℃). The medium-temperature SCR is widely applied to the power industry, and the current technology tends to be mature. However, the exhaust gas temperature of the oil and gas fired boiler is low, the moisture content is large, and the exhaust gas can reach the use requirement of medium-temperature SCR after being heated, so that the system composition is complex, the investment and operation cost is high, and the occupied space is large; and the low-temperature SCR is a new precedent for successful application in the field of denitration of oil-gas boilers.
Therefore, aiming at the characteristics of the oil-gas boiler, the research and development of the adaptive denitration process have important engineering significance and practical value.
Disclosure of Invention
The invention provides a combined denitration system and a combined denitration process for a PNCR (gas fired boiler) and a low-temperature SCR (selective catalytic reduction), which solve the problems in the prior art.
The technical scheme of the invention is realized as follows:
a denitration system is united with low temperature SCR to oil gas boiler PNCR, includes:
the PNCR denitration system comprises a conveying fan, a denitration agent hopper, a screw feeder, a gas material ejector, a distribution device and a denitration agent spray gun, wherein the denitration agent hopper, the screw feeder, the gas material ejector and the distribution device are sequentially connected, the gas material ejector is also connected with the conveying fan, a material inlet of the denitration agent spray gun is connected with the conveying fan and the distribution device, and a material outlet of the denitration agent spray gun is connected with a fuel oil and gas boiler;
the low-temperature SCR denitration system comprises an SCR reactor and a low-temperature denitration catalyst, wherein the SCR reactor is connected with the fuel oil and gas boiler, and the low-temperature denitration catalyst is arranged inside the SCR reactor.
Preferably, the conveying fan, the denitrifier hopper, the screw feeder, the gas material ejector and the distribution device are integrated in the same module.
Preferably, the number of the denitrifying agent spray guns is 1-3, the number of the oil-gas fired boilers is matched with that of the denitrifying agent spray guns, the number of the low-temperature SCR denitrifying systems is matched with that of the oil-gas fired boilers, a material inlet of each denitrifying agent spray gun is connected with the conveying fan and the distribution device, and a material outlet of each denitrifying agent spray gun is connected with one oil-gas fired boiler.
A fuel oil and gas boiler PNCR and low-temperature SCR combined denitration process based on the fuel oil and gas boiler PNCR and low-temperature SCR combined denitration system comprises the following steps:
the conveying fan introduces conveying air into the gas material ejector and introduces cooling air into the denitration agent spray gun;
the screw feeder quantitatively conveys the high-molecular denitration agent stored in the denitration agent hopper to the gas material ejector;
under the action of the conveying wind, the high-molecular denitration agent is sprayed into the flue gas through the distribution device and the denitration agent spray gun;
the high-molecular denitration agent absorbs heat in the smoke and decomposes to generate ammonia gas, the ammonia gas reacts with nitric oxide in the smoke to generate nitrogen gas and water, the PNCR denitration of the smoke is completed, and the concentration of the nitric oxide is controlled to be 40-60 mg/m3；
The flue gas after PNCR denitration enters the SCR reactor, under the action of the low-temperature denitration catalyst, the ammonia gas which does not participate in the reaction in the PNCR denitration continuously reacts with the nitric oxide in the flue gas to generate nitrogen and water, the SCR denitration of the flue gas is completed, and the concentration of the nitric oxide is controlled to be 30mg/m3The following.
Preferably, the pressure of the air conveying and supplying is 30-50 kPa, and the gas-solid ratio is 0.02-0.20 kg/kg.
Preferably, the particle size of the polymer denitration agent is 100-200 meshes.
Preferably, the temperature of the flue gas generated by the endothermic decomposition of the polymeric denitration agent in the flue gas is 600-1000 ℃.
Preferably, the use temperature of the low-temperature denitration catalyst is 140-280 ℃.
The invention has the beneficial effects that:
1. the PNCR and low-temperature SCR combined denitration system and the process of the oil-gas boiler are only modified on the flue gas side of the oil-gas boiler, do not change the combustion mode, do not change the heating surface of the boiler, do not reduce the thermal efficiency of the boiler, and are simple and reliable; the PNCR system is relatively independent from the boiler, can be used by 1-3 boilers simultaneously, and has the advantages of less modification workload, small occupied area and low investment cost;
2. according to the PNCR and low-temperature SCR combined denitration system and the process for the fuel oil and gas boiler, the high-molecular denitration agent is directly sprayed into flue gas in the form of solid powder, industrial water consumption and wastewater are not generated in the whole process, the moisture content of the flue gas cannot be increased, and the thermal efficiency of the boiler is not influenced;
3. according to the oil and gas boiler PNCR and low-temperature SCR combined denitration system and process, the optimal reaction temperature range of the high-molecular denitration agent is 600-1000 ℃, compared with SNCR, the initial reaction temperature is low, and the reaction temperature range is wide; the high-molecular denitration agent is 100-200-mesh solid powder, has a large specific surface area, is quickly decomposed to generate ammonia gas through one-step reaction after entering flue gas, completes denitration reaction, has stronger adaptability of PNCR denitration to furnace type change, and has denitration efficiency 20-30% higher than that of the SNCR technology;
4. the fuel oil and gas boiler PNCR and low-temperature SCR combined denitration system and process adopt low-temperature SCR denitration, and the low-temperature denitration catalyst is suitable for being used at the temperature of 140-280 ℃; the lowest operation temperature of the catalyst is 140 ℃, the front end of the SCR reactor does not need a heating device, the rear end does not need a waste heat utilization device, and the system resistance is only increased by 100-200 Pa, so that the investment operation cost and the floor area are saved;
5. the PNCR denitration and low-temperature SCR combined denitration system and the process thereof have the synergistic effect of PNCR denitration and low-temperature SCR denitration, fully play the characteristics of low investment and low cost of the PNCR and the characteristics of high efficiency, stability and no pollution of the low-temperature SCR, and have the advantages of high denitration efficiency, low ammonia escape, economy, practicability and the like.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
FIG. 1 is a schematic structural diagram of a PNCR and low-temperature SCR combined denitration system of an oil-gas boiler;
fig. 2 is another schematic structural diagram of a PNCR and low-temperature SCR combined denitration system of an oil-gas fired boiler according to the present invention.
In the figure:
1. a conveying fan; 2. a denitrifier hopper; 3. a screw feeder; 4. a gas feed injector; 5. a dispensing device; 6. a denitrifier spray gun; 7. an SCR reactor; 8. a low-temperature denitration catalyst; 9. oil-gas fired boiler.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As shown in fig. 1-2, the oil and gas boiler PNCR and low-temperature SCR combined denitration system of the present invention includes:
the PNCR denitration system comprises a conveying fan 1, a denitration agent hopper 2, a screw feeder 3, a gas material ejector 4, a distribution device 5 and a denitration agent spray gun 6, wherein the denitration agent hopper 2, the screw feeder 3, the gas material ejector 4 and the distribution device 5 are sequentially connected, the gas material ejector 4 is also connected with the conveying fan 1, a material inlet of the denitration agent spray gun 6 is connected with the conveying fan 1 and the distribution device 5, and a material outlet of the denitration agent spray gun 6 is connected with a fuel-gas boiler 9;
low temperature SCR deNOx systems, including SCR reactor 7 and low temperature denitration catalyst 8, SCR reactor 7 is connected with oil fired gas boiler 9, and low temperature denitration catalyst 8 is installed inside SCR reactor 7.
Wherein, preferably, the conveying fan 1, the denitrating agent hopper 2, the screw feeder 3, the gas material ejector 4 and the distribution device 5 are integrated in the same module.
Preferably, the number of the denitrifying agent spray guns 6 is 1-3, the number of the oil-gas fired boilers 9 is matched with the number of the denitrifying agent spray guns 6, the number of the low-temperature SCR denitrifying systems is matched with the number of the oil-gas fired boilers 9, a material inlet of each denitrifying agent spray gun 6 is connected with the conveying fan 1 and the distribution device 5, a material outlet of each denitrifying agent spray gun 6 is connected with one oil-gas fired boiler 9, and the number of branches connected with the distribution device 5 is 1-3.
A fuel and gas boiler PNCR and low-temperature SCR combined denitration process based on the fuel and gas boiler PNCR and low-temperature SCR combined denitration system comprises the following steps:
the conveying fan 1 introduces conveying air into the gas material ejector 4, and introduces cooling air into the denitration agent spray gun 6;
the screw feeder 3 quantitatively conveys the high-molecular denitration agent stored in the denitration agent hopper 2 to the gas material ejector 4;
under the action of conveying air, the high-molecular denitration agent is sprayed into flue gas through a distribution device 5 and a denitration agent spray gun 6;
the high-molecular denitration agent absorbs heat in the smoke and decomposes to generate ammonia gas, the ammonia gas reacts with nitric oxide in the smoke to generate nitrogen gas and water, the PNCR denitration of the smoke is completed, and the concentration of the nitric oxide is controlled to be 40-60 mg/m3；
The reaction formula is as follows: R-NH2+NOx→N2+CO2+H2O；
The flue gas after PNCR denitration enters an SCR reactor 7, under the action of a low-temperature denitration catalyst 8, ammonia gas which does not participate in the reaction in PNCR denitration continuously reacts with nitric oxide in the flue gas to generate nitrogen and water, the SCR denitration of the flue gas is completed, and the concentration of the nitric oxide is controlled to be 30mg/m3The following.
The reaction formula is as follows: NO +4NH3→5N2+6H2O or 6NO2+8NH3→7N2+12H2O。
Wherein, preferably, the pressure of the air conveying is 30-50 kPa, and the gas-solid ratio is 0.02-0.20 kg/kg.
Wherein, the particle size of the polymer denitration agent is preferably 100-200 meshes.
Preferably, the temperature of the flue gas generated by the endothermic decomposition of the polymeric denitration agent in the flue gas to generate ammonia is 600-1000 ℃.
Wherein, the use temperature of the low-temperature denitration catalyst 8 is preferably 140-280 ℃.
Compared with the prior art, the invention has the following beneficial effects:
1. low nitrogen combustion technologyMethod for reducing NO by changing combustion mode and reducing combustion temperaturexThe generation of the heat energy can cause the reduction of the heat efficiency of the boiler and increase the operation cost of the boiler; meanwhile, the low-nitrogen combustor is expensive and high in investment cost; in practical application, a certain amount of standby boilers are generally arranged in an oil-gas boiler room, the use frequency is limited, a low-nitrogen combustion technology is adopted, and a combustor needs to be replaced for both a common boiler and a standby boiler, and a flue is modified; the invention only carries out the reformation on the flue gas side of the oil and gas boiler, does not change the combustion mode, does not change the heating surface of the boiler, does not reduce the thermal efficiency of the boiler, and is simple and reliable; the PNCR system is relatively independent from the boiler, can be used by 1-3 boilers simultaneously, and has the advantages of less modification workload, small occupied area and low investment cost;
2. the SNCR technology adopts ammonia water or urea as a denitration agent, and the ammonia water or urea needs to be diluted into 5% ammonia water or 10% urea solution before being sprayed into the boiler, so that a large amount of water is sprayed into flue gas, water is evaporated to absorb heat, the moisture content of the flue gas is increased, and the thermal efficiency of the boiler is influenced; according to the invention, the high-molecular denitration agent is directly sprayed into the flue gas in the form of solid powder, no industrial water consumption and no wastewater are generated in the whole process, the moisture content of the flue gas cannot be increased, and the thermal efficiency of a boiler is not influenced;
3. according to the SNCR technology, ammonia water or urea is used as a denitration agent, so that on one hand, the reaction temperature is high, the optimal reaction temperature range of the ammonia water is 870-1100 ℃, and the optimal reaction temperature range of the urea is 900-1150 ℃; on the other hand, the ammonia water cannot be used in a resident concentration area, so that urea can only be used as a denitration agent of SNCR for a plurality of gas-fired boilers; the optimum reaction temperature of the urea is higher, the urea is sprayed into the flue gas in a solution form, and the ammonia gas can be generated for denitration reaction only by two steps of water evaporation and solid urea decomposition, so that the denitration efficiency is greatly influenced by factors such as flue gas temperature, flow field condition, retention time and the like, and the denitration efficiency is very low when the denitration catalyst is applied to a small fuel oil and gas boiler with a compact structure; the optimal reaction temperature range of the high-molecular denitration agent adopted by PNCR denitration is 600-1000 ℃, the initial reaction temperature is lower than that of SNCR, and the reaction temperature range is wide; the denitration agent is 100-200 meshes of solid powder, has a large specific surface area, and is quickly decomposed to generate ammonia gas through one-step reaction after entering flue gas to complete denitration reaction; the adaptability of PNCR denitration to furnace type change is stronger, and the denitration efficiency is 20-30% higher than that of the SNCR technology;
4. the low-temperature SCR is the main direction for the development of the denitration technology, but the low-temperature activity and the anti-poisoning capability of the current low-temperature denitration catalyst are generally poor, the actual use temperature is generally more than 200 ℃, and the temperature rise of flue gas is still needed; although the low-temperature SCR can save certain heating energy consumption and reduce the operation cost compared with the medium-temperature SCR, for a large number of fuel oil and gas boilers arranged indoors, the site space is limited, and the large-scale reconstruction condition is not provided, the invention adopts low-temperature SCR denitration, the suitable use temperature of the low-temperature denitration catalyst is 140-280 ℃, the minimum operation temperature of the catalyst is 140 ℃, the front end of the SCR reactor does not need heating equipment, the rear end does not need waste heat utilization equipment, and meanwhile, the system resistance is only increased by 100-200 Pa, so that the investment operation cost and the floor area are saved;
5. the PNCR denitration and the low-temperature SCR denitration synergistic effect fully play the characteristics of low investment and low cost of the PNCR and the characteristics of high efficiency, stability and no pollution of the low-temperature SCR, and have the advantages of high denitration efficiency, low ammonia escape, economy, practicability and the like.
Technically, NO can also be achieved by a combination of the prior art-low-nitrogen burner, selective non-catalytic reduction SNCR and selective catalytic reduction SCR, such as low-nitrogen combustion + SCR, or SNCR + SCRxBut has obvious influence on the efficiency of the boiler, higher investment cost and poorer applicability to the boiler type. The temperature is a key factor influencing the efficiency of the SCR catalyst, and the catalyst applied to the oil-gas boiler has the characteristics of wide operating temperature range and low activation temperature, otherwise, a proper temperature section may not exist, so how to readjust and organically combine the prior art to realize a perfect or best scheme has many factors to be considered, and creative labor needs to be paid.
For a better understanding of the present invention, specific examples are provided below:
the first embodiment is as follows:
in the embodiment of the invention, the oil and gas boiler 9 is a hot water boiler with model number WNS-10.5-1.25-115/70-Y (Q) and three return strokes, the design smoke temperature is 90 ℃, and the initial NO isxThe concentration is 100mg/m3。
The conveying fan 1 introduces conveying air with the pressure not lower than 50kPa into the gas material ejector 4, and cooling air is introduced into the denitrifying agent spray gun 6; the screw feeder 3 quantitatively conveys the high-molecular denitration agent with the particle size of 100-120 meshes stored in the denitration agent hopper 2 to the gas material ejector 4; keeping the gas-solid ratio of 0.02-0.10 kg/kg; under the action of conveying air, the high-molecular denitration agent is sprayed into flue gas through a distribution device 5 and a denitration agent spray gun 6; the denitration agent spray gun 6 is installed on an access door of the oil and gas boiler 9, the high-molecular denitration agent is sprayed into a boiler combustion chamber, and the temperature of the sprayed ignition gas is 800-900 ℃; the high molecular denitration agent absorbs heat to decompose in the flue gas to generate ammonia gas, the ammonia gas reacts with nitric oxide in the flue gas to generate nitrogen gas and water, the PNCR denitration of the flue gas is completed, and the concentration of the nitric oxide is controlled to be 50mg/m3；
The SCR reactor 7 is arranged between a second return stroke and a third return stroke of the oil-gas fired boiler 9, and the temperature of flue gas at the inlet of the reactor is 140-200 ℃; the flue gas after PNCR denitration enters an SCR reactor 7, under the action of a low-temperature denitration catalyst 8, the ammonia gas which does not participate in the reaction continuously reacts with the nitrogen oxide in the flue gas to generate nitrogen and water, the SCR denitration of the flue gas is completed, and the concentration of the nitrogen oxide is controlled to be 30mg/m3The following.
Example two:
in the embodiment of the invention, the oil and gas boiler 9 is a steam boiler with model number WNS-4-2.45-Y (Q) and two return strokes, the design exhaust gas temperature is 152 ℃, and the initial NO isxThe concentration is 125mg/m3。
The conveying fan 1 introduces conveying air with the pressure not lower than 30kPa into the gas material ejector 4, and cooling air is introduced into the denitrifying agent spray gun 6; the screw feeder 3 quantitatively conveys the high-molecular denitration agent with the particle size of 150-200 meshes stored in the denitration agent hopper 2 to the gas material ejector 4; keeping the gas-solid ratio of 0.10-0.20 kg/kg; under the action of conveying air, the high-molecular denitration agent is sprayed into flue gas through a distribution device 5 and a denitration agent spray gun 6; denitrationThe agent spray gun 6 is installed on an access door of a fuel oil and gas boiler 9, the high-molecular denitration agent is sprayed into a boiler combustion chamber, and the temperature of the sprayed ignition gas is 850-1000 ℃; the high molecular denitration agent absorbs heat to decompose in the flue gas to generate ammonia gas, the ammonia gas reacts with nitric oxide in the flue gas to generate nitrogen gas and water, the PNCR denitration of the flue gas is completed, and the concentration of the nitric oxide is controlled to be 60mg/m3；
The SCR reactor 7 is arranged at a second return outlet of the oil-gas boiler 9, and the temperature of the flue gas at the inlet of the reactor is 152 ℃; the flue gas after PNCR denitration enters an SCR reactor 7, under the action of a low-temperature denitration catalyst 8, the ammonia gas which does not participate in the reaction continuously reacts with the nitrogen oxide in the flue gas to generate nitrogen and water, the SCR denitration of the flue gas is completed, and the concentration of the nitrogen oxide is controlled to be 30mg/m3The following.
Example three:
in the embodiment of the invention, the oil and gas fired boiler 9 is a gas fired hot water boiler with the model of SZS29-1.6-130/70-Q, the rated water supply/return temperature is 130 ℃/70 ℃, the designed smoke exhaust temperature is 92 ℃, and the designed thermal efficiency is 95.19%; the boiler adopts a low-nitrogen burner with the model of GT35U and the rated thermal power of 35 MW; three boilers, each boiler uses independent steel chimney to discharge smoke, the content of nitrogen oxide in the smoke is not more than 100mg/m3The conveying fan 1 introduces conveying air with the pressure not lower than 40kPa into the gas material ejector 4, and cooling air is introduced into the denitrifying agent spray gun 6; the screw feeder 3 quantitatively conveys the high-molecular denitration agent with the particle size of 120-150 meshes stored in the denitration agent hopper 2 to the gas material ejector 4; keeping the gas-solid ratio of 0.02-0.10 kg/kg; under the action of conveying air, the high-molecular denitration agent is sprayed into flue gas through a distribution device 5 and a denitration agent spray gun 6; the denitration agent spray gun 6 is installed on an access door of the oil and gas boiler 9, the high-molecular denitration agent is sprayed into a boiler combustion chamber, and the temperature of the sprayed ignition gas is 600-800 ℃; the high molecular denitration agent absorbs heat to decompose in the flue gas to generate ammonia gas, the ammonia gas reacts with nitric oxide in the flue gas to generate nitrogen gas and water, the PNCR denitration of the flue gas is completed, and the concentration of the nitric oxide is controlled to be 50mg/m3；
The SCR reactor 7 is arranged between the second return stroke and the third return stroke of the oil-gas boiler 9, and the flue gas temperature at the inlet of the reactor is 140 to200 ℃; the flue gas after PNCR denitration enters an SCR reactor 7, under the action of a low-temperature denitration catalyst 8, the ammonia gas which does not participate in the reaction continuously reacts with the nitrogen oxide in the flue gas to generate nitrogen and water, the SCR denitration of the flue gas is completed, and the concentration of the nitrogen oxide is controlled to be 30mg/m3The following test results were obtained by adjusting the boiler load:
boiler load/(MW) 8.58 13.15 21.66 28.68
Load factor/(%) 29.6 45.3 74.7 98.9
Oxygen content in flue gas/(%) 3.02 2.95 2.88 2.56
Original NOxEmission mass concentration/(mg/m)3) 70.82 74.62 88.91 94.56
NO after PNCR denitrationxEmission mass concentration/(mg/m)3) 34.61 36.68 37.15 36.37
NO after SCR denitrationxEmission mass concentration/(mg/m)3) 13.49 15.54 12.86 11.52
The above illustrates the main innovative points of the present invention, and the non-mentioned parts are the conventional techniques in the art, and can be implemented by those skilled in the art without inventive efforts. The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims (8)

1. The utility model provides a denitration system is united with low temperature SCR to oil gas boiler PNCR which characterized in that includes:
the PNCR denitration system comprises a conveying fan (1), a denitration agent hopper (2), a screw feeder (3), a gas material ejector (4), a distribution device (5) and a denitration agent spray gun (6), wherein the denitration agent hopper (2), the screw feeder (3), the gas material ejector (4) and the distribution device (5) are sequentially connected, the gas material ejector (4) is further connected with the conveying fan (1), a material inlet of the denitration agent spray gun (6) is connected with the conveying fan (1) and the distribution device (5), and a material outlet of the denitration agent spray gun (6) is connected with a fuel-gas boiler (9);
the low-temperature SCR denitration system comprises an SCR reactor (7) and a low-temperature denitration catalyst (8), wherein the SCR reactor (7) is connected with the oil-gas boiler (9), and the low-temperature denitration catalyst (8) is arranged inside the SCR reactor (7).
2. A combined oil and gas boiler PNCR and low temperature SCR denitration system according to claim 1, wherein the conveyor fan (1), the denitration agent hopper (2), the screw feeder (3), the gas injector (4) and the distribution device (5) are integrated in the same module.
3. The PNCR and low-temperature SCR combined denitration system of the oil-gas boiler according to claim 1, wherein the number of the denitration agent spray guns (6) is 1-3, the number of the oil-gas boiler (9) is matched with the number of the denitration agent spray guns (6), the number of the low-temperature SCR denitration system is matched with the number of the oil-gas boiler (9), a material inlet of each denitration agent spray gun (6) is connected with the conveying fan (1) and the distribution device (5), and a material outlet of each denitration agent spray gun (6) is connected with one oil-gas boiler (9).
4. The oil-gas boiler PNCR and low-temperature SCR combined denitration process is characterized by comprising the following steps of:
the conveying fan (1) introduces conveying air into the gas material ejector (4), and introduces cooling air into the denitration agent spray gun (6);
the screw feeder (3) quantitatively conveys the high-molecular denitration agent stored in the denitration agent hopper (2) to the gas material ejector (4);
under the action of the conveying wind, the high-molecular denitration agent is sprayed into flue gas through the distribution device (5) and the denitration agent spray gun (6);
the high-molecular denitration agent absorbs heat in the smoke and decomposes to generate ammonia gas, and the ammonia gas reacts with nitric oxide in the smokeGenerating nitrogen and water to finish PNCR denitration of flue gas, and controlling the concentration of the nitrogen oxide to be 40-60 mg/m3；
The flue gas after PNCR denitration enters the SCR reactor (7), under the action of the low-temperature denitration catalyst (8), ammonia gas which does not participate in the reaction in PNCR denitration continuously reacts with nitric oxide in the flue gas to generate nitrogen and water, the SCR denitration of the flue gas is completed, and the concentration of the nitric oxide is controlled to be 30mg/m3The following.
5. The PNCR and low-temperature SCR combined denitration method for the oil-gas boiler is characterized in that the pressure of the air conveying and supplying is 30-50 kPa, and the gas-solid ratio is 0.02-0.20 kg/kg.
6. The oil and gas boiler PNCR and low-temperature SCR combined denitration method according to claim 4, wherein the particle size of the polymer denitration agent is 100-200 meshes.
7. The PNCR and low-temperature SCR combined denitration method for the oil-gas boiler as claimed in claim 4, wherein the temperature of the flue gas generated by the endothermic decomposition of the polymeric denitration agent in the flue gas is 600-1000 ℃.
8. The oil and gas boiler PNCR and low-temperature SCR combined denitration method according to claim 4, wherein the use temperature of the low-temperature denitration catalyst (8) is 140-280 ℃.
CN202010983661.6A 2020-09-18 2020-09-18 Fuel oil and gas boiler PNCR and low-temperature SCR combined denitration system and process Pending CN112090254A (en)

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