WO2021051937A1 - 一种用于水泥烟气的scr脱硝系统 - Google Patents

一种用于水泥烟气的scr脱硝系统 Download PDF

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WO2021051937A1
WO2021051937A1 PCT/CN2020/099101 CN2020099101W WO2021051937A1 WO 2021051937 A1 WO2021051937 A1 WO 2021051937A1 CN 2020099101 W CN2020099101 W CN 2020099101W WO 2021051937 A1 WO2021051937 A1 WO 2021051937A1
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ammonia water
soot blowing
flue gas
reducing agent
scr
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PCT/CN2020/099101
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English (en)
French (fr)
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朱廷钰
郭旸旸
朱思佳
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中国科学院过程工程研究所
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Publication of WO2021051937A1 publication Critical patent/WO2021051937A1/zh

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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
    • B01D53/46—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
    • B01D53/75—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
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/77—Liquid phase processes
    • B01D53/79—Injecting reactants
    • 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
    • B01D53/8631—Processes characterised by a specific device
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D17/00—Arrangements for using waste heat; Arrangements for using, or disposing of, waste gases
    • F27D17/004—Systems for reclaiming waste heat
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D17/00—Arrangements for using waste heat; Arrangements for using, or disposing of, waste gases
    • F27D17/008—Arrangements for using waste heat; Arrangements for using, or disposing of, waste gases cleaning gases
    • 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
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D17/00—Arrangements for using waste heat; Arrangements for using, or disposing of, waste gases
    • F27D17/004—Systems for reclaiming waste heat
    • F27D2017/006—Systems for reclaiming waste heat using a boiler
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/25—Process efficiency

Definitions

  • the application belongs to the field of flue gas treatment, and relates to an SCR denitration system for cement flue gas.
  • China's cement kiln flue gas denitrification mainly adopts selective non-catalytic reduction (SNCR) technology, and the NO x removal efficiency is about 60%. At present, it basically meets the GB4915-2013 "Cement Industry Air Pollution Emission Standard", but its denitrification efficiency is low. , The amount of ammonia escaped is large, and it is difficult to meet the ultra-low emission standards that will be implemented in the future.
  • SCR selective catalytic reduction
  • the selective catalytic reduction (SCR) denitrification technology has mild reaction conditions and high denitrification efficiency (90%), and its application in the thermal power industry has been very mature.
  • the application of SCR denitration technology in the cement industry is still less, because the dust content of the kiln tail gas of the cement production line is as high as 80-120g/Nm 3 , and the high content of CaO in the dust will cause blockage, poisoning and deactivation of the catalyst bed. ,
  • the catalyst has a short service life and high system operating costs.
  • the high temperature and high dust arrangement is to arrange the SCR device between the suspension preheater C1 and the waste heat boiler.
  • the flue gas temperature here is 340 ⁇ 360°C, which meets the temperature requirements of the current mature commercial catalysts, but the flue gas contains high dust content. If it is ensured that the catalyst is not blocked and the SCR operates stably and continuously, increasing the cross-sectional aperture of the catalyst will inevitably increase the volume of the reactor, increase the floor space and investment cost.
  • the high temperature and medium dust arrangement is to increase the pre-dust collector of the SCR reactor on the basis of high temperature and high dust to reduce the dust entering the reactor.
  • the efficiency of electric dust removal at 340 ⁇ 360°C is difficult to meet the requirements, and the bag filter is at this temperature. Special material cloth bags with high temperature resistance are also required for operation.
  • the medium temperature and medium dust arrangement is to arrange the pre-cleaner and the SCR reactor after the waste heat boiler, where the flue gas temperature is 180-220°C.
  • the low-temperature and low-dust arrangement is to arrange the SCR reactor after the bag filter, where the smoke and dust content is extremely low, and the flue gas temperature is 80 ⁇ 130 °C.
  • CN107596917A discloses an SNCR-SCR device and process for kiln tail flue gas of a cement clinker production line.
  • the intermediate temperature flue gas (340-360°C) downstream of the kiln tail preheater is used to achieve the evaporation of ammonia in the SCR denitration section.
  • the low-temperature flue gas (90-110°C) introduced by the chimney through the dilution fan is mixed and then sent to the SCR reactor.
  • the temperature of the flue gas entering the SCR reactor meets the requirements of the conventional SCR catalyst, and the denitration reaction can be carried out efficiently.
  • the invention does not use a pre-cleaner, and the high-dust flue gas from the suspension preheater directly enters the SCR reactor, causing blockage, poisoning and deactivation of the catalyst bed, and the catalyst has a short service life.
  • a coiled ammonia water evaporator is arranged on the inlet flue of the SCR reactor, the ammonia water passes through the pipe side, and the flue gas passes through the shell side, and the high-temperature flue gas (320-360°C) at the inlet of the reactor is used to vaporize the ammonia water in the coil. This process does not require an additional heat source to gasify ammonia, but the coil structure in the pipeline is complicated, which increases the overall flue gas flow resistance.
  • CN204555717U discloses a cement kiln tail mid-temperature flue gas SCR denitration device.
  • the denitration device is after a waste heat boiler.
  • the high temperature and high dust flue gas from the kiln tail preheater is used for waste heat through the waste heat power generation boiler, and the flue gas temperature is reduced.
  • Enter the cyclone dust collector for dust collection treatment the dust concentration in the flue gas is further reduced, and the reductant supply system is supplied to the reductant injection device arranged on the front pipe of the cyclone dust collector to spray into the flue.
  • the agent enters the medium temperature denitration device with catalyst for denitration.
  • a cyclone dust collector is arranged in front of the SCR reactor, which can reduce the dust entering the SCR reactor, but the dust particles of cement kiln flue gas are small and the efficiency of the cyclone dust collector is limited.
  • This application provides an SCR denitration system for cement flue gas, which solves the problems of catalyst fouling and clogging when the SCR denitration process is applied to a cement production line, prone to alkali poisoning, prolongs the useful life of the catalyst, and makes full use of the kiln There is no additional heat source for the exhaust gas heat, which is energy-saving and high-efficiency, and the system operation cost is low.
  • This application provides an SCR denitration system for cement flue gas.
  • the system is set between the waste heat boiler and the raw meal mill of the cement production device, and includes a pre-dust removal device, a reducing agent injection device and an SCR reactor connected in sequence,
  • the waste heat boiler is connected to the pre-dust removal device, and the raw meal mill is connected to the SCR reactor;
  • the reducing agent injection device is connected to the reducing agent preparation system
  • the SCR reactor is connected with an air soot blowing system.
  • the inlet of the waste heat boiler is connected with the flue gas outlet of the soot blowing air heating device, and the flue gas inlet of the soot blowing air heating device is connected with the kiln tail flue.
  • the pre-dust removal device includes any one of an electric dust collector, a bag filter, or an electric bag composite dust collector.
  • the reducing agent injection device is any one of a grid type, a vortex type or a hybrid type.
  • the reducing agent preparation system includes a reducing agent dilution fan, an ammonia evaporator, an ammonia storage tank, an ammonia pump, and an ammonia spray gun.
  • the inlet of the reducing agent dilution fan is connected to the outlet flue of the pre-dust removal device, the outlet of the reducing agent dilution fan is connected to the inlet of the ammonia water evaporator, and the outlet of the ammonia water evaporator is connected to the reducing agent injection device,
  • the ammonia water spray gun is arranged inside the ammonia water evaporator, and the ammonia water spray gun is connected with the outlet of the ammonia water pump, and the inlet of the ammonia water pump is connected with the ammonia water storage tank.
  • the ammonia water evaporator is provided with 2 to 3 ammonia water spray guns, the ammonia water spray gun atomizes the ammonia water pumped by the ammonia water into small droplets and sprays into the ammonia water evaporator; the reducing agent dilution fan draws hot smoke from the pre-dust collector
  • the gas is fed in from the bottom of the ammonia evaporator, the ammonia is evaporated into gas by the heat of the flue gas, and the mixture is diluted to about 20% ammonia concentration, and sent from the top of the ammonia evaporator to the reductant injection device.
  • the dilution air volume is adjusted by the dilution fan.
  • the ammonia water pump is connected to the ammonia water storage tank, and the ammonia water is drawn out and pumped to the ammonia water spray gun.
  • the ammonia water injection volume is adjusted by the ammonia water pump.
  • SCR process can choose liquid ammonia, urea, ammonia water as reducing agents.
  • Liquid ammonia has a certain degree of danger, is flammable and explosive, and has a certain toxicity.
  • the use of liquid ammonia as a reducing agent requires a high level of safety for the equipment list.
  • urea as the reducing agent, the reducing agent preparation system is complicated, and the investment and operating costs are high. Therefore, this application uses ammonia water as the reducing agent, which is safe, cost-effective and efficient.
  • the air soot blowing system includes a soot blowing nozzle, the soot blowing air heating device, and a compressed air storage tank, the outlet of the compressed air storage tank and the air inlet of the soot blowing air heating device Connected, the air outlet of the soot blowing air heating device is connected with the soot blowing nozzle, and the soot blowing nozzle is located inside the SCR reactor.
  • this application is equipped with a catalyst soot blowing device.
  • catalyst soot blowing There are several forms of catalyst soot blowing, sonic soot blowing, steam soot blowing and compressed air soot blowing.
  • the energy of sonic soot blowing is small, which can only loosen the ash accumulation, and cannot completely remove the small particles of floating ash, and cannot remove the cohesive ash accumulation and serious ash clogging; the high humidity of steam soot blowing can corrode the catalyst and reduce the activity of the catalyst.
  • the service life of the catalyst is reduced; the compressed air blowing efficiency is high, the adhesive dust can be blown away, and the operation reliability is high. Therefore, this application uses compressed air blowing.
  • the temperature of the soot blowing compressed air must be the same as the catalyst reaction temperature.
  • high-temperature flue gas from the kiln tail is used to heat the compressed air, and there is no need to install an independent heat source.
  • the pressure inside the compressed air storage tank is 0.6 to 1.0 MPa, such as 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa or 1.0 MPa, etc., but it is not limited to the listed values, and other values within this range Values not listed also apply.
  • the temperature of the compressed air after being heated by the flue gas heating device is 200-280°C, such as 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C or 280°C, etc., but not limited to the listed values, and other unlisted values within this range of values are also applicable.
  • the pressure of the compressed air sprayed by the soot blowing nozzle is 0.5 to 1.9 MPa, such as 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa, 1.0 MPa, 1.1 MPa, 1.2 MPa, 1.3 MPa, 1.4 MPa, 1.5 MPa, 1.6 MPa, 1.7 MPa, 1.8 MPa or 1.9 MPa, etc., but not limited to the listed values, and other unlisted values within this range of values are also applicable.
  • a baffle plate, a rectifying device and a catalyst bed are arranged inside the SCR reactor, and the catalyst bed is located below the soot blowing nozzle.
  • the soot blowing nozzles are arranged in the SCR denitration reactor, and each layer of catalyst bed corresponds to several nozzles, and the specific number is determined by the size of the catalyst bed.
  • the catalyst in the catalyst bed is a monolithic catalyst resistant to poisoning by alkali and alkaline earth metals.
  • it can be V-Mo-Ti/SiO 2 , but it is not limited to this catalyst.
  • Catalysts resistant to alkali and alkaline earth metal poisoning can be used in this application.
  • the shape of the catalyst is any one or a combination of at least two of a honeycomb type, a plate type or a corrugated type.
  • the reaction temperature window of the catalyst is 200-240°C, such as 200°C, 205°C, 210°C, 215°C, 220°C, 225°C, 230°C, 235°C or 240°C, but not limited to For the listed values, other unlisted values within the range of values are also applicable.
  • the process flow of the SCR denitration system for cement flue gas provided in this application is: the high-temperature flue gas discharged from the kiln tail enters the waste heat boiler to use the waste heat after the soot blowing air heating device, and the flue gas temperature drops, and then enters the pre-dust removal device for dust removal , The flue gas temperature further drops. After the reductant injection device, the flue gas is mixed with the reducing agent and enters the SCR reactor for denitration reaction.
  • the flue gas temperature after denitration does not change much, and enters the raw meal mill, drying the raw meal, and the flue gas The temperature drops again, and then enters the dust removal device to remove dust, and the purified flue gas is sent to the chimney to be discharged by the fan.
  • the SCR denitration system is combined with the SNCR system.
  • the SCR denitrification system described in this application can be combined with the SNCR system. After the combined use, the two systems share the reducing agent preparation device, reducing equipment investment. After SNCR denitration, the load of the SCR reactor is reduced, the number of catalyst beds can be appropriately reduced, the NO x removal efficiency can be improved, and the investment cost and operating cost can be further reduced.
  • This application uses an efficient medium temperature SCR denitration catalyst, and the NO x content of the purified flue gas can meet the strict ultra-low emission standards in the future, reaching 50mg/Nm 3 or even lower;
  • the SCR reactor is arranged after the waste heat boiler, and a pre-dust removal device is installed.
  • the waste heat boiler can make full use of the heat of high-temperature smoke and dust, reduce energy waste, and remove a part of the smoke and dust, reducing the load of the pre-dust removal device;
  • the pre-dust removal device adopts
  • the electrostatic precipitator or the bag filter or the electric bag composite dust collector is adapted to the small emission characteristics of the dust particles at the tail of the cement kiln.
  • the dust removal efficiency is over 90%, which greatly reduces the dust entering the SCR reactor and solves the problem of catalyst blockage;
  • This application adopts a compressed air soot blowing device, which uses high-temperature flue gas from the kiln tail to heat the compressed air, which has high soot blowing efficiency, no corrosion to the catalyst, stable and reliable operation, and energy-saving and economical;
  • This application uses ammonia water as the reducing agent, which has higher safety and economy compared with commonly used liquid ammonia and urea.
  • the flue gas after the pre-cleaner is used as the heat source for the evaporation of ammonia, and the ammonia is diluted, reducing the construction investment of a separate heat source.
  • Figure 1 is a schematic structural diagram of an SCR denitration system for cement flue gas provided in Example 1 of the present application;
  • the specific embodiment of the present application provides an SCR denitration system for cement flue gas.
  • the system is set between the waste heat boiler and the raw meal mill of the cement production device, and includes a pre-dust removal device, a reducing agent injection device, and an SCR connected in sequence.
  • a reactor, the waste heat boiler is connected to the pre-dust removal device, and the raw meal mill is connected to the SCR reactor;
  • the reducing agent injection device is connected to the reducing agent preparation system
  • the SCR reactor is connected with an air soot blowing system.
  • the reducing agent preparation device includes a reducing agent dilution fan, an ammonia evaporator, an ammonia storage tank, an ammonia pump, and an ammonia spray gun; the inlet of the reducing agent dilution fan is connected to the outlet flue of the pre-dust removal device, so The outlet of the reducing agent dilution fan is connected with the inlet of the ammonia water evaporator, the outlet of the ammonia water evaporator is connected with the reducing agent injection device, the ammonia water spray gun is arranged inside the ammonia water evaporator, the ammonia water spray gun and the outlet of the ammonia water pump The inlet of the ammonia water pump is connected with the ammonia water storage tank.
  • the air soot blowing system includes a soot blowing nozzle, a soot blowing air heating device, and a compressed air storage tank.
  • the outlet of the compressed air storage tank is connected to the air inlet of the soot blowing air heating device.
  • the air outlet of the heating device is connected with the soot blowing nozzle, and the soot blowing nozzle is located inside the SCR reactor.
  • a baffle plate and a catalyst bed are arranged inside the SCR reactor, and the catalyst bed is located below the soot blowing nozzle.
  • the SCR reactor is connected to a flue gas humidification device, the flue gas humidification device is arranged in parallel with the raw meal mill, and the outlet of the flue gas humidification device is connected to a kiln tail dust removal device.
  • the outlet of the kiln tail dust removal device is connected with a fan, and the outlet of the fan is connected with a chimney.
  • the process flow of the SCR denitrification system for cement flue gas provided in the specific implementation mode of this application is: the high-temperature flue gas (340-360°C) discharged from the kiln tail is heated by the flue gas heating device and then enters the waste heat boiler to use the waste heat and the flue gas The temperature drops to 240 ⁇ 260°C, and then enters the pre-dust removal device for dust removal. The flue gas temperature further drops to 200 ⁇ 240°C. After the reductant injection device, the flue gas is mixed with the reductant and enters the SCR reactor for denitration reaction.
  • the flue gas temperature does not change much, it enters the raw meal mill, the raw meal is dried, and the flue gas temperature is reduced to 100-120°C again, and then enters the dust removal device for dust removal, and the purified flue gas is sent to the chimney to be discharged by the fan.
  • This embodiment provides an SCR denitration system for cement flue gas, the structure of which is shown in FIG. 1.
  • the SCR denitration system includes a soot blowing air heater 17, a waste heat boiler 2, a pre-dust collector 3, a reducing agent injection device 4, an SCR reactor 5, a raw meal mill 6 and a bag filter 8 connected in sequence; soot blowing air heating
  • the flue gas inlet of the kiln 17 is connected to the high temperature flue 1 at the kiln tail; the outlet of the bag filter 8 is connected to a fan 9, and the outlet of the fan 9 is connected to the chimney 10.
  • the SCR reactor 5 is connected to a humidification tower 7, the humidification tower 7 is arranged in parallel with the raw mill 6, and the outlet of the humidification tower 7 is connected to the bag filter 8.
  • the SCR denitration system is provided with a reductant preparation system, and the reductant injection device 4 is connected to the reductant preparation system;
  • the reductant preparation system includes a reductant dilution fan 11, an ammonia water evaporator 12, an ammonia water storage tank 13, and ammonia Water pump 14 and ammonia spray gun 15;
  • the inlet of the reducing agent dilution fan 11 is connected to the outlet of the pre-dust collector 3
  • the outlet of the reducing agent dilution fan 11 is connected to the inlet of the ammonia evaporator 12, and the outlet of the ammonia evaporator 12 is connected to the reducing agent injection device 4
  • the ammonia water evaporator 12 is provided with the ammonia water spray gun 15 inside, the ammonia water spray gun 15 is connected to the outlet of the ammonia water pump 14, and the inlet of the ammonia water pump 14 is connected to the ammonia water storage tank 13.
  • the SCR denitration system is provided with an air soot blowing system, and the SCR reactor 5 is connected to the soot blowing system.
  • the soot blowing system includes a compressed air storage tank 16 and at least one soot blowing nozzle 18.
  • the compressed air storage tank 16 Connected to the soot blowing air heater 17, the compressed air is heated by the soot blowing air heater 17 and then enters the soot blowing nozzle 18 through a pipe.
  • the soot blowing nozzle 18 is located inside the SCR reactor 5 and blows
  • the ash nozzle is located above the catalyst bed, and each catalyst bed corresponds to at least one nozzle.
  • the kiln tail high temperature flue 1 after the kiln tail preheater is connected to the soot blowing air heater 17, the waste heat boiler 2. After the waste heat is used, the flue gas enters the pre-dust collector 3, after passing through the reductant injection device 4, it enters the SCR reactor 5 Carry out the denitration reaction; the flue gas after denitration enters the raw meal mill 6, the raw meal is dried and cooled, and then enters the bag filter 8 for dust removal, and the purified flue gas is sent to the chimney through the fan 9 for discharge 10.
  • the flue gas is switched to the humidification tower No. 7. After the flue gas is humidified and cooled, the filter bag of the bag filter 8 can be protected from burning.
  • the hot flue gas is drawn from the pre-cleaner 3, pressurized by the reducing agent dilution fan 11, and then sent to the ammonia evaporator 12.
  • the dilution air is sent from the bottom of the ammonia evaporator 12, after evaporating the ammonia and diluting the ammonia, the ammonia evaporator 12 is sent from the top to the reducing agent injection device 4, and the dilution air volume is adjusted by the dilution fan 11.
  • the ammonia water evaporator 12 is provided with an ammonia water spray gun 15 which atomizes the ammonia water sent by the ammonia water pump 14 into small droplets and sprays it into the ammonia water evaporator.
  • the ammonia water pump 14 is connected to the ammonia water storage tank 13 to extract and pump the ammonia water to the ammonia water spray gun 15, and the ammonia water injection amount is adjusted by the ammonia water pump 14.
  • the denitrification experiment was carried out on a 4000t/d new dry process cement kiln production line, this cement production line has been installed with an SNCR denitrification device.
  • the high-temperature flue gas at the kiln tail has a dust concentration of 70g/Nm 3 , a temperature of 380°C, a NO x concentration of 300 mg/Nm 3 , and a flue gas flow rate of 430,000 Nm 3 /h.
  • a three-field electric precipitator is used as the pre-cleaner 3; the reductant injection device 4 adopts a grid type; the catalyst bed adopts a three-for-one arrangement; the catalyst adopts a honeycomb-type monolithic catalyst with a cross-sectional aperture of 0.5 cm, the reaction temperature window is 220°C; 20% ammonia water is used as the reducing agent, and the ammonia water injection volume is 145L/h.
  • the compressed air source is the public compressed air in the factory, and the soot blowing frequency is 4 times a day.
  • the temperature drops to 240°C.
  • the temperature is 220°C and the particle concentration drops to 7.2g/Nm 3 .
  • the gas is denitrified, it enters the raw meal mill 6 to dry the raw meal, the temperature is reduced to 120 °C, and then is sent to the chimney by the main fan after passing through the bag filter.
  • the final exhaust temperature is 95°C, the dust content is 15mg/Nm 3 , and the NO x concentration is 28.6mg/Nm 3 .
  • the denitration experiment was carried out on a 3200t/d new dry process cement kiln production line.
  • the dust concentration of the high-temperature flue gas at the kiln tail is 60g/Nm 3
  • the temperature is 360°C
  • the NO x concentration is 420mg/Nm 3
  • the flue gas flow rate is 380,000Nm 3 /h.
  • a three-field electric precipitator is used as the pre-cleaner 3; the reductant injection device 4 adopts a grid type; the catalyst bed adopts a three-for-one arrangement; the catalyst adopts a honeycomb-type monolithic catalyst with a cross-sectional aperture of 1.0 cm, the reaction temperature window is 200°C; the rake-type steam soot blower is used, and the soot blowing frequency is once a week; 20% ammonia water is used as the reducing agent, and the ammonia water injection volume is 182L/h.
  • the compressed air source is the public compressed air in the factory, and the soot blowing frequency is twice a day.
  • the temperature drops to 220°C.
  • the temperature is 200°C and the particle concentration drops to 5.6g/Nm 3.
  • the reductant injection device 4 After passing through the reductant injection device 4, it enters the SCR reactor 5.
  • the gas After the gas is denitrified, it enters the raw meal mill 6 to dry the raw meal, the temperature is reduced to 110 °C, and then after the bag filter, it is sent to the chimney by the main fan for discharge.
  • the final exhaust temperature is 90°C, the dust content is 18mg/Nm 3 , and the NO x concentration is 36.5mg/Nm 3 .
  • the denitrification experiment was carried out on a 2000t/d new dry process cement kiln production line, and the cement production line has been installed with an SNCR denitrification device.
  • the dust concentration of the high-temperature flue gas at the kiln tail is 80g/Nm 3
  • the temperature is 340°C
  • the NO x concentration is 200mg/Nm 3
  • the flue gas flow rate is 280,000Nm 3 /h.
  • a high-temperature-resistant bag filter is used as the pre-dust collector 3; the reductant injection device 4 adopts a vortex type; the catalyst bed adopts a two-for-one arrangement, and the catalyst adopts a honeycomb-type monolithic catalyst with a cross-sectional aperture of 1.5cm
  • the reaction temperature window is 200°C; the rake-type steam soot blower is used, and the soot blowing frequency is once a week; 20% ammonia water is used as the reducing agent, and the ammonia water injection volume is 64L/h.
  • the compressed air source is an independent air compressor, and the soot blowing frequency is twice a day.
  • the flue gas passes through the waste heat boiler 2, the temperature drops to 220°C, after passing through the pre-cleaner, the temperature is 200°C, and the particle concentration drops to 0.8g/Nm 3 , after passing through the reductant injection device 4, it enters the SCR reactor 5.
  • the gas After the gas is denitrified, it enters the raw meal mill 6 to dry the raw meal, the temperature is reduced to 110 °C, and then after the bag filter, it is sent to the chimney by the main fan for discharge.
  • the final exhaust temperature is 90°C, the dust content is 13mg/Nm 3 , and the NO x concentration is 12.8mg/Nm 3 .
  • the catalyst in the catalyst bed in Examples 2-4 of the present application is V-Mo-Ti/SiO 2 .
  • Example 2 Flue dust emissions declined by 99.98%, NO x concentration decreased by 90.47% compared to the original flue gas;

Abstract

本申请提供一种用于水泥烟气的SCR脱硝系统，所述系统设置于水泥生产装置的余热锅炉与生料磨之间，包括依次连接的预除尘装置、还原剂喷射装置以及SCR反应器，所述余热锅炉与所述预除尘装置相连，所述生料磨与所述SCR反应器相连；所述还原剂喷射装置与还原剂制备系统相连；所述SCR反应器与空气吹灰系统相连。

Description

一种用于水泥烟气的SCR脱硝系统 技术领域
本申请属于烟气处理领域，涉及一种用于水泥烟气的SCR脱硝系统。
背景技术
我国的水泥窑烟气脱硝主要采用有选择性非催化还原(SNCR)技术，NO x脱除效率在60％左右，目前基本满足GB4915-2013《水泥工业大气污染排放标准》，但是其脱硝效率低，氨逃逸量大，难以满足未来必将执行的超低排放标准。选择性催化还原(SCR)脱硝技术反应条件温和，脱硝效率高(90％)，在火电行业应用已经非常成熟。但是水泥行业的SCR脱硝技术应用还较少，因为水泥生产线窑尾烟气的含尘量高达80～120g/Nm 3，且粉尘中CaO含量高，将会造成催化剂床层堵塞、中毒和失活，催化剂使用寿命短，系统运行成本高。
根据水泥生产线的特性，主要有四种SCR脱硝工艺方案，分别是高温高尘、高温中尘、中温中尘和低温低尘布置方案。高温高尘布置是将SCR装置布置在悬浮预热器C1与余热锅炉之间，此处烟气温度为340～360℃，满足目前成熟的商用催化剂温度要求，但是此处烟气含尘量高，若保证催化剂不堵塞、SCR稳定连续运行，要增大催化剂截面孔径，势必会增大反应器体积，增加占地面积与投资成本。高温中尘布置是在高温高尘的基础上增加SCR反应器前置除尘器，减少进入反应器的粉尘，而在340～360℃下电除尘的效率难以达到要求，布袋除尘器在此温度下运行也需要耐高温的特殊材质布袋。中温中尘布置是将预除尘器和SCR反应器布置在余热锅炉之后，此处烟气温度为180～220℃，目前已有此温度区间成熟的商用催化剂，是一个可行的方案。低温低尘布置是将SCR反应器布置在布袋除尘器之后，此处烟尘含量极低，烟气温度为80～130℃，目前 还没有成熟的催化剂产品，而将烟温升至与现有成熟催化剂相适应的温度，将会消耗额外的能源。
CN107596917A公开了一种水泥熟料生产线窑尾烟气的SNCR-SCR装置及工艺，利用窑尾预热器下游的中温烟气(340～360℃)实现SCR脱硝段的氨水蒸发，与自窑尾烟囱经由稀释风机引入的低温烟气(90～110℃)混合后送入SCR反应器中，进入SCR反应器的烟气温度满足常规SCR催化剂的要求，能够使脱硝反应高效进行。该发明未采用预除尘器，从悬浮预热器出来的高尘烟气直接进入SCR反应器，造成催化剂床层堵塞、中毒和失活，催化剂使用寿命短。该发明在SCR反应器的进口烟道上设置盘管氨水蒸发器，氨水走管程，烟气走壳程，利用反应器进口的高温烟气(320～360℃)将盘管内氨水气化。此工艺无需设置额外热源气化氨水，但是管道内的盘管结构复杂，增加总体烟气流动阻力。
CN204555717U公开了一种水泥窑尾中温烟气SCR脱硝装置，其脱硝装置在余热锅炉之后，来自窑尾预热器的高温高尘烟气经由余热发电锅炉进行余热利用，烟气温度有所降低后，进入旋风收尘器进行收尘处理，烟气中的粉尘浓度进一步降低，与有还原剂供应系统供应的通过至布置在旋风收尘器前管道上的还原剂喷射装置喷射至烟道内的还原剂一起进入装有催化剂的中温脱硝装置进行脱硝。此工艺在SCR反应器前布置了旋风收尘器，可以降低进入SCR反应器的粉尘，但是水泥窑烟气粉尘颗粒细小，旋风收尘器效率有限。
发明内容
以下是对本文详细描述的主题的概述。本概述并非是为了限制权利要求的保护范围。
本申请提供一种用于水泥烟气的SCR脱硝系统，所述系统解决了SCR脱硝 工艺应用于水泥生产线时，催化剂积灰堵塞，容易碱中毒的问题，延长催化剂的适用寿命，并充分利用窑尾烟气热量，不增设额外热源，节能高效，系统运行成本低。
为达上述目的，本申请采用以下技术方案：
本申请提供一种用于水泥烟气的SCR脱硝系统，所述系统设置于水泥生产装置的余热锅炉与生料磨之间，包括依次连接的预除尘装置、还原剂喷射装置以及SCR反应器，所述余热锅炉与所述预除尘装置相连，所述生料磨与所述SCR反应器相连；
所述还原剂喷射装置与还原剂制备系统相连；
所述SCR反应器与空气吹灰系统相连。
作为本申请可选的技术方案，所述余热锅炉的入口与吹灰空气加热装置的烟气出口相连，吹灰空气加热装置的烟气入口与窑尾烟道相连。
作为本申请可选的技术方案，所述预除尘装置包括电除尘器、布袋除尘器或电袋复合除尘器中的任意一种。
作为本申请可选的技术方案，所述还原剂喷射装置为格栅型，涡流型或混合型中的任意一种。
作为本申请可选的技术方案，所述还原剂制备系统包括还原剂稀释风机、氨水蒸发器、氨水储罐、氨水泵以及氨水喷枪。
可选地，所述还原剂稀释风机入口与所述预除尘装置的出口烟道相连，所述还原剂稀释风机出口与氨水蒸发器入口相连，所述氨水蒸发器出口与还原剂喷射装置相连，所述氨水蒸发器内部设置有所述氨水喷枪，所述氨水喷枪与所述氨水泵的出口相连，所述氨水泵的入口与所述氨水储罐相连。
其中，所述氨水蒸发器内设置有2到3个氨水喷枪，氨水喷枪将氨水泵送来的氨水雾化成小液滴喷入氨水蒸发器内；还原剂稀释风机从预除尘器后引出热烟气，从氨水蒸发器底部送入，利用烟气的热量将氨水蒸发成气体，并稀释成大约20％氨气浓度的混合气，从氨水蒸发器顶部送出，至还原剂喷射装置。稀释风量通过稀释风机调节。氨水泵连接氨水储罐，将氨水抽出并泵送至氨水喷枪，氨水喷射量通过氨水泵调节。
SCR工艺可以选用液氨、尿素、氨水作为还原剂。液氨具有一定的危险性，易燃易爆，且有一定毒性，使用液氨作为还原剂，对设备单的安全等级要求高。采用尿素作为还原剂，还原剂制备系统复杂，投资费用和运行费用高。所以本申请采用氨水作为还原剂，安全经济高效。
作为本申请可选的技术方案，所述空气吹灰系统包括吹灰喷嘴、所述吹灰空气加热装置以及压缩空气储罐，所述压缩空气储罐出口与所述吹灰空气加热装置空气进口相连，所述吹灰空气加热装置空气出口与所述吹灰喷嘴相连，所述吹灰喷嘴位于所述SCR反应器内部。
为防止催化剂积灰，本申请设置催化剂吹灰装置。催化剂吹灰有声波吹灰，蒸汽吹灰和压缩空气吹灰几种形式。声波吹灰能量较小，只能使积灰松散脱离，无法彻底清除颗粒小的浮灰，对粘结性积灰和严重堵灰无法清除；蒸汽吹灰湿度大，腐蚀催化剂，降低催化剂活性，减少催化剂使用寿命；压缩空气吹灰效率高，可以吹去粘结性灰尘，运行可靠性高，所以本申请采用压缩空气吹灰。
为防止催化剂骤冷开裂，消除吹灰后的升温启动时间，提高脱硝效率，减少氨气逃逸，吹灰压缩空气温度要和催化剂反应温度一致。本申请利用窑尾高温烟气加热压缩空气，不必设置独立热源。
可选地，所述压缩空气储罐内部的压力为0.6～1.0MPa，如0.6MPa、0.7MPa、0.8MPa、0.9MPa或1.0MPa等，但并不仅限于所列举的数值，该数值范围内其他未列举的数值同样适用。
可选地，所述压缩空气经所述烟气加热装置加热后的温度为200～280℃，如200℃、210℃、220℃、230℃、240℃、250℃、260℃、270℃或280℃等，但并不仅限于所列举的数值，该数值范围内其他未列举的数值同样适用。
可选地，所述吹灰喷嘴喷出的压缩空气的压力为0.5～1.9MPa，如0.5MPa、0.6MPa、0.7MPa、0.8MPa、0.9MPa、1.0MPa、1.1MPa、1.2MPa、1.3MPa、1.4MPa、1.5MPa、1.6MPa、1.7MPa、1.8MPa或1.9MPa等，但并不仅限于所列举的数值，该数值范围内其他未列举的数值同样适用。
作为本申请可选的技术方案，所述SCR反应器内部设置有导流板、整流装置和催化剂床层，所述催化剂床层位于所述吹灰喷嘴下方。
本申请中，吹灰喷嘴设置在SCR脱硝反应器内，每一层催化剂床层对应若干喷嘴，具体数量由催化剂床层大小确定。
可选地，所述催化剂床层中的催化剂为耐碱及碱土金属中毒的整体式催化剂。例如可以是V-Mo-Ti/SiO 2，但并不仅限于该催化剂，耐碱及碱土金属中毒的催化剂均可用于本申请。
可选地，所述催化剂的形状为蜂窝式、板式或波纹式中的任意一种或至少两种的组合。
可选地，所述催化剂的反应温度窗口为200～240℃，如200℃、205℃、210℃、215℃、220℃、225℃、230℃、235℃或240℃等，但并不仅限于所列举的数值，该数值范围内其他未列举的数值同样适用。
本申请提供的用于水泥烟气的SCR脱硝系统的工艺流程为：窑尾排出的高温烟气经吹灰空气加热装置后进入余热锅炉利用余热，烟气温度下降，然后进入预除尘装置进行除尘，烟气温度进一步下降，经还原剂喷射装置后烟气与还原剂混合，进入SCR反应器进行脱硝反应，脱硝后的烟气温度变化不大，进入生料磨，烘干生料，烟气温度再次降低，然后进入除尘装置除尘，净化后的烟气经风机送至烟囱排放。
作为本申请可选的技术方案，将所述SCR脱硝系统与SNCR系统联用。
目前大多数水泥生产线上已经安装SNCR脱硝系统，因此作为可选方案，本申请所述SCR脱硝系统可以与SNCR系统联用。联用后两套系统共用还原剂制备装置，减少设备投资。经过SNCR脱硝后，SCR反应器负荷减轻，可以适当减少催化剂床层数，提高NO x脱除效率，进一步降低投资成本与运行成本。
与现有技术方案相比，本申请至少具有以下有益效果：
(1)本申请采用高效的中温SCR脱硝催化剂，净化后烟气的NO x含量可以满足未来严格的超低排放标准，到达50mg/Nm 3，甚至更低；
(2)本申请将SCR反应器布置在余热锅炉后，并设置预除尘装置，余热锅炉可以充分利用高温烟尘的热量，减少能源浪费，并且去除一部分烟尘，减轻预除尘装置负荷；预除尘装置采用电除尘器或布袋除尘器或电袋复合除尘器，适应水泥窑尾烟尘颗粒细小的排放特点，除尘效率达90％以上，大幅减少了进入SCR反应器的粉尘，解决了催化剂堵塞问题；
(3)本申请采用压缩空气吹灰装置，利用窑尾高温烟气加热压缩空气，吹灰效率高，对催化剂无腐蚀作用，运行稳定可靠，节能经济；
(4)本申请采用氨水作为还原剂，与常用的液氨、尿素相比，具有更高的 安全性和经济性。利用预除尘器后的烟气作为氨水蒸发的热源，并将氨气稀释，减少了单独热源的建设投资。
在阅读并理解了详细描述和附图后，可以明白其他方面。
附图说明
图1是本申请实施例1提供的用于水泥烟气的SCR脱硝系统的结构示意图；
图中：1-窑尾高温烟道，2-余热锅炉，3-预除尘器，4-还原剂喷射装置，5-SCR反应器，6-生料磨，7-增湿塔，8-布袋除尘器，9-风机，10-烟囱，11-还原剂稀释风机，12-氨水蒸发器，13-氨水储罐，14-氨水泵，15-氨水喷枪，16-压缩空气储罐，17-吹灰空气加热器，18-吹灰喷嘴。
下面对本申请进一步详细说明。但下述的实例仅仅是本申请的简易例子，并不代表或限制本申请的权利保护范围，本申请的保护范围以权利要求书为准。
具体实施方式
下面结合附图并通过具体实施方式来进一步说明本申请的技术方案。
本申请具体实施方式提供一种用于水泥烟气的SCR脱硝系统，所述系统设置于水泥生产装置的余热锅炉与生料磨之间，包括依次连接的预除尘装置、还原剂喷射装置以及SCR反应器，所述余热锅炉与所述预除尘装置相连，所述生料磨与所述SCR反应器相连；
所述还原剂喷射装置与还原剂制备系统相连；
所述SCR反应器与空气吹灰系统相连。
可选地，所述还原剂制备装置包括还原剂稀释风机、氨水蒸发器、氨水储罐、氨水泵以及氨水喷枪；所述还原剂稀释风机入口与所述预除尘装置的出口烟道相连，所述还原剂稀释风机出口与氨水蒸发器入口相连，所述氨水蒸发器 出口与还原剂喷射装置相连，所述氨水蒸发器内部设置有所述氨水喷枪，所述氨水喷枪与所述氨水泵的出口相连，所述氨水泵的入口与所述氨水储罐相连。
可选地，所述空气吹灰系统包括吹灰喷嘴、吹灰空气加热装置以及压缩空气储罐，所述压缩空气储罐出口与所述吹灰空气加热装置空气进口相连，所述吹灰空气加热装置空气出口与所述吹灰喷嘴相连，所述吹灰喷嘴位于所述SCR反应器内部。
可选地，所述SCR反应器内部设置有导流板和催化剂床层，所述催化剂床层位于所述吹灰喷嘴下方。
可选地，所述SCR反应器与烟气增湿装置相连，所述烟气增湿装置与所述生料磨并联设置，所述烟气增湿装置的出口与窑尾除尘装置相连。
可选地，所述窑尾除尘装置的出口与风机相连，所述风机的出口与烟囱相连。
本申请具体实施方式部分提供的用于水泥烟气的SCR脱硝系统的工艺流程为：窑尾排出的高温烟气(340～360℃)经烟气加热装置加热后进入余热锅炉利用余热，烟气温度下降至240～260℃，然后进入预除尘装置进行除尘，烟气温度进一步下降至200～240℃，经还原剂喷射装置后烟气与还原剂混合，进入SCR反应器进行脱硝反应，脱硝后的烟气温度变化不大，进入生料磨，烘干生料，烟气温度再次降低至100～120℃，然后进入除尘装置除尘，净化后的烟气经风机送至烟囱排放。
为更好地说明本申请，便于理解本申请的技术方案，本申请的典型但非限制性的实施例如下：
实施例1
本实施例提供一种用于水泥烟气的SCR脱硝系统，其结构如图1所示。
所述SCR脱硝系统包括依次连接的吹灰空气加热器17、余热锅炉2、预除尘器3、还原剂喷射装置4、SCR反应器5、生料磨6以及布袋除尘器8；吹灰空气加热器17的烟气入口与窑尾高温烟道1相连；所述布袋除尘器8的出口与风机9相连，所述风机9的出口与烟囱10相连。
所述SCR反应器5与增湿塔7相连，所述增湿塔7与所述生料磨6并联设置，所述增湿塔7的出口与所述布袋除尘器8相连。
所述SCR脱硝系统设置有还原剂制备系统，所述还原剂喷射装置4与还原剂制备系统相连；所述还原剂制备系统包括还原剂稀释风机11、氨水蒸发器12、氨水储罐13、氨水泵14以及氨水喷枪15；所述还原剂稀释风机11的进口与预除尘器3出口相连，还原剂稀释风机11的出口与氨水蒸发器12入口相连，氨水蒸发器12出口与还原剂喷射装置4相连，所述氨水蒸发器12内部设置有所述氨水喷枪15，所述氨水喷枪15与所述氨水泵14的出口相连，所述氨水泵14的入口与所述氨水储罐13相连。
所述SCR脱硝系统设置有空气吹灰系统，所述SCR反应器5与吹灰系统相连，所述吹灰系统包括压缩空气储罐16以及至少一个吹灰喷嘴18，所述压缩空气储罐16与所述吹灰空气加热器17相连，压缩空气通过所述吹灰空气加热器17加热后通过管道进入所述吹灰喷嘴18，所述吹灰喷嘴18位于所述SCR反应器5内部，吹灰喷嘴位于催化剂床层上方，每一层催化剂床层对应至少一个喷嘴。
窑尾预热器后的窑尾高温烟道1连接吹灰空气加热器17，余热锅炉2，烟气经余热利用后，进入预除尘器3，经过还原剂喷射装置4后，进入SCR反应 器5进行脱硝反应；脱硝后的烟气进入生料磨6，烘干生料并降温，然后进入布袋除尘器8除尘，净化后的烟气经风机9送至烟囱排放10。
当生料磨6不工作时，烟气切换至增湿塔7路，烟气增湿降温后，可以保护布袋除尘器8的滤袋不被烧毁。
从预除尘器3后引出热烟气，经过还原剂稀释风机11增压后送入氨水蒸发器12，稀释风从氨水蒸发器12底部送入，蒸发氨水并稀释氨气后，由氨水蒸发器12顶部送出，至还原剂喷射装置4，稀释风量通过稀释风机11调节。
氨水蒸发器12内设置氨水喷枪15，氨水喷枪将氨水泵14送来的氨水雾化成小液滴喷入氨水蒸发器内。氨水泵14连接氨水储罐13，将氨水抽出并泵送至氨水喷枪15，氨水喷射量通过氨水泵调节14。
实施例2
利用实施例1所述的装置，在一条4000t/d的新型干法水泥窑生产线上进行脱硝实验，此水泥生产线已经安装SNCR脱硝装置。窑尾高温烟气的含尘浓度为70g/Nm 3，温度为380℃，NO x浓度为300mg/Nm 3，烟气流量为430000Nm 3/h。
本实施例中选用三电场电除尘器作为与预除尘器3；还原剂喷射装置4采用格栅型；催化剂床层采用用三备一的布置方式，催化剂采用蜂窝式整体催化剂，截面孔径为0.5cm，反应温度窗口为220℃；采用20％的氨水作为还原剂，氨水喷射量为145L/h。压缩空气源为厂内公用压缩空气，吹灰频率为一天4次。
烟气经过余热锅炉2后，温度降至240℃，经预除尘器后，温度为220℃，颗粒物浓度降为7.2g/Nm 3，经过还原剂喷射装置4后，进入SCR反应器5，烟气脱硝后，进入生料磨6烘干生料，温度降至120℃，然后经布袋除尘器后，由 主风机送至烟囱排放。最终排烟温度为95℃，含尘量15mg/Nm 3，NO x浓度为28.6mg/Nm 3。
实施例3
利用实施例1所述的装置，在一条3200t/d的新型干法水泥窑生产线上进行脱硝实验。窑尾高温烟气的含尘浓度为60g/Nm 3，温度为360℃，NO x浓度为420mg/Nm 3，烟气流量为380000Nm 3/h。
本实施例中选用三电场电除尘器作为与预除尘器3；还原剂喷射装置4采用格栅型；催化剂床层采用用三备一的布置方式，催化剂采用蜂窝式整体催化剂，截面孔径为1.0cm，反应温度窗口为200℃；采用耙式蒸气吹灰器，吹灰频率为一周一次；采用20％的氨水作为还原剂，氨水喷射量为182L/h。压缩空气源为厂内公用压缩空气，吹灰频率为一天2次。
烟气经过余热锅炉2后，温度降至220℃，经预除尘器后，温度为200℃，颗粒物浓度降为5.6g/Nm 3，经过还原剂喷射装置4后，进入SCR反应器5，烟气脱硝后，进入生料磨6烘干生料，温度降至110℃，然后经布袋除尘器后，由主风机送至烟囱排放。最终排烟温度为90℃，含尘量18mg/Nm 3，NO x浓度为36.5mg/Nm 3。
实施例4
利用实施例1所述的装置，在一条2000t/d的新型干法水泥窑生产线上进行脱硝实验，此水泥生产线已经安装SNCR脱硝装置。窑尾高温烟气的含尘浓度为80g/Nm 3，温度为340℃，NO x浓度为200mg/Nm 3，烟气流量为280000Nm 3/h。
本实施例中选用耐高温布袋除尘器作为与预除尘器3；还原剂喷射装置4采用涡流型；催化剂床层采用用二备一的布置方式，催化剂采用蜂窝式整体催化剂，截面孔径为1.5cm，反应温度窗口为200℃；采用耙式蒸气吹灰器，吹灰频率为一周一次；采用20％的氨水作为还原剂，氨水喷射量为64L/h。压缩空气源为独立空压机，吹灰频率为一天2次。
烟气经过余热锅炉2后，温度降至220℃，经预除尘器后，温度为200℃，颗粒物浓度降为0.8g/Nm 3，经过还原剂喷射装置4后，进入SCR反应器5，烟气脱硝后，进入生料磨6烘干生料，温度降至110℃，然后经布袋除尘器后，由主风机送至烟囱排放。最终排烟温度为90℃，含尘量13mg/Nm 3，NO x浓度为12.8mg/Nm 3。
本申请实施例2-4中催化剂床层中的催化剂为V-Mo-Ti/SiO 2。
从实施例2-4的测试结果可以看出，经实施例1提供的用于水泥烟气的SCR脱硝系统对烟气进行处理后，与原始烟气相比，排放烟气中的含尘量以及NO x浓度均明显下降。实施例2中排放烟气与原始烟气相比含尘量下降了99.98％，NO x浓度下降了90.47％；实施例3中排放烟气与原始烟气相比含尘量下降了99.97％，NO x浓度下降了91.31％；实施例4中排放烟气与原始烟气相比含尘量下降了99.98％，NO x浓度下降了93.60％。
申请人声明，本申请通过上述实施例来说明本申请的详细结构特征，但本申请并不局限于上述详细结构特征，即不意味着本申请必须依赖上述详细结构特征才能实施。所属技术领域的技术人员应该明了，对本申请的任何改进，对本申请所选用部件的等效替换以及辅助部件的增加、具体方式的选择等，均落在本申请的保护范围和公开范围之内。
以上详细描述了本申请的可选实施方式，但是，本申请并不限于上述实施方式中的具体细节，在本申请的技术构思范围内，可以对本申请的技术方案进行多种简单变型，这些简单变型均属于本申请的保护范围。
另外需要说明的是，在上述具体实施方式中所描述的各个具体技术特征，在不矛盾的情况下，可以通过任何合适的方式进行组合，为了避免不必要的重复，本申请对各种可能的组合方式不再另行说明。

Claims (10)

  1. 一种用于水泥烟气的SCR脱硝系统，其中，所述系统设置于水泥生产装置的余热锅炉与生料磨之间，包括依次连接的预除尘装置、还原剂喷射装置以及SCR反应器，所述余热锅炉与所述预除尘装置相连，所述生料磨与所述SCR反应器相连；
    所述还原剂喷射装置与还原剂制备系统相连；
    所述SCR反应器与空气吹灰系统相连。
  2. 根据权利要求1所述的SCR脱硝系统，其中，所述预除尘装置包括电除尘器、布袋除尘器或电袋复合除尘器中的任意一种。
  3. 根据权利要求1或2所述的SCR脱硝系统，其中，所述还原剂喷射装置为格栅型，涡流型或混合型中的任意一种。
  4. 根据权利要求1-3任一项所述的SCR脱硝系统，其中，所述还原剂喷射装置与还原剂制备系统相连；
    可选地，所述还原剂制备系统包括还原剂稀释风机、氨水蒸发器、氨水储罐、氨水泵以及氨水喷枪；
    可选地，所述还原剂稀释风机入口与所述预除尘装置的出口烟道相连，所述还原剂稀释风机出口与氨水蒸发器入口相连，所述氨水蒸发器出口与还原剂喷射装置相连，所述氨水蒸发器内部设置有所述氨水喷枪，所述氨水喷枪与所述氨水泵的出口相连，所述氨水泵的入口与所述氨水储罐相连。
  5. 根据权利要求1-4任一项所述的SCR脱硝系统，其中，所述空气吹灰系统包括吹灰喷嘴、所述吹灰空气加热装置以及压缩空气储罐，所述压缩空气储罐出口与所述吹灰空气加热装置空气进口相连，所述吹灰空气加热装置空气出口与所述吹灰喷嘴相连，所述吹灰喷嘴位于所述SCR反应器内部；
    可选地，所述压缩空气储罐内部的压力为0.6～1.0MPa；
    可选地，所述压缩空气经所述烟气加热装置加热后的温度为200～280℃；
    可选地，所述吹灰喷嘴喷出的压缩空气的压力为0.6～1.0MPa。
  6. 根据权利要求5所述的SCR脱硝系统，其中，所述余热锅炉的入口与吹灰空气加热装置的烟气出口相连，吹灰空气加热装置的烟气入口与窑尾烟道相连。
  7. 根据权利要求1-6任一项所述的SCR脱硝系统，其中，所述SCR反应器内部设置有导流板、整流装置和催化剂床层，所述催化剂床层位于所述吹灰喷嘴下方；
    可选地，所述催化剂床层中的催化剂为耐碱及碱土金属中毒的整体式催化剂。
  8. 根据权利要求1-7任一项所述的SCR脱硝系统，所述催化剂的形状为蜂窝式、板式或波纹式中的任意一种或至少两种的组合；
    可选地，所述催化剂的反应温度窗口为200～240℃。
  9. 根据权利要求1-8任一项所述的SCR脱硝系统，其中，所述除尘装置的出口与风机相连，所述风机的出口与烟囱相连。
  10. 根据权利要求1-9任一项所述的SCR脱硝系统，其中，将所述SCR脱硝系统与SNCR系统联用。
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