CN220443543U - SNCR spouts meticulous regulation and control degree of depth denitration system of ammonia - Google Patents
SNCR spouts meticulous regulation and control degree of depth denitration system of ammonia Download PDFInfo
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- CN220443543U CN220443543U CN202321948012.8U CN202321948012U CN220443543U CN 220443543 U CN220443543 U CN 220443543U CN 202321948012 U CN202321948012 U CN 202321948012U CN 220443543 U CN220443543 U CN 220443543U
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- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 title claims abstract description 139
- 229910021529 ammonia Inorganic materials 0.000 title claims abstract description 68
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims abstract description 99
- 235000011114 ammonium hydroxide Nutrition 0.000 claims abstract description 99
- 239000007921 spray Substances 0.000 claims abstract description 85
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 45
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims abstract description 38
- 239000003546 flue gas Substances 0.000 claims abstract description 38
- 238000000889 atomisation Methods 0.000 claims abstract description 31
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- 238000002347 injection Methods 0.000 claims abstract description 29
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- 238000003860 storage Methods 0.000 claims abstract description 26
- 238000002156 mixing Methods 0.000 claims abstract description 25
- 239000003638 chemical reducing agent Substances 0.000 claims abstract description 19
- 239000012530 fluid Substances 0.000 claims description 38
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- 238000011033 desalting Methods 0.000 claims description 14
- 230000001276 controlling effect Effects 0.000 claims description 13
- 239000007788 liquid Substances 0.000 claims description 13
- 238000001514 detection method Methods 0.000 claims description 6
- 238000010790 dilution Methods 0.000 claims description 5
- 239000012895 dilution Substances 0.000 claims description 5
- 239000010963 304 stainless steel Substances 0.000 claims description 4
- 229910000589 SAE 304 stainless steel Inorganic materials 0.000 claims description 4
- 239000000463 material Substances 0.000 claims description 4
- 229910001220 stainless steel Inorganic materials 0.000 claims description 4
- 239000010935 stainless steel Substances 0.000 claims description 4
- 238000009529 body temperature measurement Methods 0.000 claims description 2
- 238000005520 cutting process Methods 0.000 claims description 2
- 238000007865 diluting Methods 0.000 claims description 2
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- 241000282326 Felis catus Species 0.000 claims 1
- 238000005192 partition Methods 0.000 abstract description 5
- 239000000243 solution Substances 0.000 abstract description 5
- 238000006243 chemical reaction Methods 0.000 description 9
- 238000000034 method Methods 0.000 description 9
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 9
- 238000010531 catalytic reduction reaction Methods 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 238000005516 engineering process Methods 0.000 description 5
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- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonium chloride Substances [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 description 4
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- 238000007599 discharging Methods 0.000 description 4
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- 238000010521 absorption reaction Methods 0.000 description 3
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- 239000002245 particle Substances 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- BIGPRXCJEDHCLP-UHFFFAOYSA-N ammonium bisulfate Chemical compound [NH4+].OS([O-])(=O)=O BIGPRXCJEDHCLP-UHFFFAOYSA-N 0.000 description 2
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- 239000003245 coal Substances 0.000 description 2
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- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 1
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- 239000010881 fly ash Substances 0.000 description 1
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- JEGUKCSWCFPDGT-UHFFFAOYSA-N h2o hydrate Chemical compound O.O JEGUKCSWCFPDGT-UHFFFAOYSA-N 0.000 description 1
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Abstract
The utility model discloses an SNCR ammonia injection fine regulation and control deep denitration system, which belongs to the technical field of flue gas treatment and comprises a reducing agent storage and supply unit, a desalted water unit, a metering and mixing unit, a fine distribution unit and an atomization injection unit; the metering and mixing unit mixes and dilutes the ammonia water of the reducing agent storage and supply unit and the desalted water of the desalted water unit into diluted ammonia water, and the diluted ammonia water enters the atomizing and spraying unit through the fine distributing unit and is sprayed into the flue gas after ultra-high fine atomization. The system can accurately regulate the flow of each spray gun, and is convenient for evenly distributing the ammonia water solution to a plurality of corresponding spray guns so as to achieve the purpose of fully and evenly mixing with the flue gas. Meanwhile, according to the feedback of the thermocouple temperatures of the spray gun partition arrangement, any spray gun can be remotely thrown in and cut off. By the mode, stability and efficiency of SNCR denitration are improved, consumption of ammonia water is reduced, ammonia escapes in a controllable range, and running cost is reduced.
Description
Technical Field
The utility model belongs to the technical field of flue gas treatment, and particularly relates to an SNCR ammonia spraying fine regulation and control deep denitration system.
Background
The disclosure of this background section is only intended to increase the understanding of the general background of the utility model and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art already known to those of ordinary skill in the art.
Nitrogen oxides in atmospheric pollutants are easily influenced by atmospheric acid rain and photochemical smog, so that the greenhouse effect of an ozone layer is damaged to a certain extent, and serious harm is brought to the natural environment and human health. In recent years, NO in China x The total emission amount is high, and the coal-fired power plant is NO x The most discharged industry, according to statistics, has 60 percent of NO in the atmospheric pollutants in China x The coal consumption of the thermal power plant accounts for 70% of the coal consumption of China. Therefore, a denitration system is needed to be adopted for the boiler of the thermal power plant, and NO is comprehensively controlled x Is used for the discharge amount of the fuel.
The denitration technology commonly used in the market at present comprises a selective non-catalytic reduction reaction (SNCR) and a selective catalytic reduction reaction (SCR), and an SNCR/SCR combined flue gas denitration technology developed on the basis of the selective non-catalytic reduction reaction (SNCR) and the selective catalytic reduction reaction (SCR). The most widely applied selective non-catalytic reduction denitration technology belongs to a denitration method for reducing nitrogen oxides in flue gas into harmless nitrogen and water by using a reducing agent under the condition of no catalyst. The method comprises the steps of firstly spraying a reducing agent containing amino into a proper temperature area in a hearth. At high temperature, the reducing agent is rapidly decomposed into ammonia and reacts with nitrogen oxides in the flue gas in a reduction way to generate nitrogen and water. The process takes the hearth as a reactor, has the advantages of simple system, convenient control, relatively low investment, short construction period and the like, and stands out in a plurality of denitration technologies.
The inventors have found that SNCR reduction reactions need to be performed within a specific temperature range in order to provide sufficient thermal energy to drive the reaction. When the temperature is too low, the power of the reduction reaction is too weak, so that a large amount of ammonia can escape; at too high a temperature, the reducing agent is oxidized to form additional NO x . Meanwhile, the mixing degree of the reducing agent and the flue gas and the residence time in the optimal temperature window are also key to influence the efficiency of the SNCR denitration process. The SNCR denitration efficiency of the common SNCR in the market at present is basically about 50%, and in order to improve the efficiency, a large amount of ammonia is sprayed by some power plants without cost, so that the ammonia water consumption is far greater than a theoretical value, and the ammonia escape is serious. The excessive ammonia injection is extremely harmful to the operation of the boiler. Unreacted ammonia (escaped ammonia) will produce ammonium bisulfate. Ammonium bisulfate is a high-viscosity liquid substance which is easy to condense and deposit on the surface of a heat exchange element of an air preheater, and fly ash particles in flue gas are easy to adhere to the high-viscosity liquid substance to block the passage of the heat exchange element, so that the resistance of the air preheater is increased, the heat exchange effect is influenced, the heat exchanger is greatly damaged, the service life of the air preheater is seriously influenced, and the running cost is increased.
Therefore, the ammonia spraying amount in the SNCR denitration process is urgently required to be finely regulated, so that the denitration efficiency of the SNCR is effectively improved, the escape amount of ammonia is reduced, and the utilization rate of the ammonia is improved.
Disclosure of Invention
In order to solve the defects of the prior art, the utility model aims to provide the SNCR ammonia spraying fine regulation and control deep denitration system, which can effectively improve the utilization rate of ammonia, avoid the generation of escaped ammonia, improve the denitration efficiency and save the operation cost.
In order to achieve the above purpose, the technical scheme of the utility model is as follows:
in a first aspect of the utility model, there is provided an SNCR ammonia injection fine control depth denitration system, comprising a reductant storage and supply unit, a demineralized water unit, a metering and mixing unit, a fine distribution unit and an atomization injection unit;
the reducing agent storage and supply unit includes: an ammonia water storage tank and an ammonia water delivery pump; the ammonia water conveying pump is used for conveying the ammonia water in the ammonia water storage tank to the metering unit;
the demineralized water unit includes: a desalting water tank and a desalting water conveying pump; the desalted water conveying pump is used for conveying the dilution water in the desalted water tank to the metering unit;
the metering and mixing unit comprises: a mixer for diluting the ammonia water supplied by the ammonia water delivery pump and the desalted water supplied by the desalted water delivery pump into dilute ammonia water with a target concentration in the mixer;
the fine distribution unit includes: a dilute ammonia water pipeline and a compressed air pipeline which are connected with the atomization injection unit; the device is used for conveying the dilute ammonia water in the metering unit to the atomization injection unit through a dilute ammonia water pipeline and conveying the compressed air to the atomization injection unit through a compressed air pipeline;
the atomizing injection unit is used for spraying the atomized dilute ammonia water and compressed air into the flue gas, and comprises: the device comprises a double-fluid atomizing spray gun and a temperature detection device, wherein the temperature detection device is used for detecting the temperature of the double-fluid atomizing spray gun; each double-fluid atomizing spray gun is connected with a dilute ammonia water pipeline and a compressed air pipeline.
The temperature of the hearth is taken as the most direct, most timely and most important parameter of the combustion condition in the reaction hearth, is the most direct operation basis of SNCR denitration optimization, intuitively judges and adjusts the temperature distribution in the hearth, and adjusts ammonia injection to be in the optimal reaction temperature range (850-1050 ℃), so that in order to improve denitration efficiency and save ammonia injection quantity, corresponding temperature measuring points are required to be arranged at each spray gun zone, and corresponding spray guns are put into operation according to temperature feedback.
In some embodiments of the present utility model, the reducing agent storage and supply unit further includes an ammonia unloading pump for transferring ammonia in the ammonia tank truck to an ammonia storage tank for storage; the ammonia water unloading pump is a multistage centrifugal pump, is made of stainless steel, and is corrosion-resistant and durable.
In some embodiments of the utility model, the ammonia water storage tank is made of 304 stainless steel, and is provided with a manhole, a breather valve, a material inlet and outlet, an overflow port, an evacuation port, a temperature measurement port, a liquid level measurement port, a climbing ladder and the like.
In some embodiments of the present utility model, the ammonia water delivery pump is a multistage centrifugal pump, and is made of stainless steel, and is used for delivering the ammonia water in the ammonia water storage tank to the metering mixing unit for dilution. The outlet of the ammonia water delivery pump is provided with an electric regulating valve group, and the opening degree of the electric regulating valve is used for controlling the pressure of the delivery pump outlet to be a stable value, and the pressure is generally controlled to be about 1.0 Mpa. Only under the premise that the pressure and the flow on the pipeline are stable and controllable, the ultra-high atomization effect of the double-fluid atomization spray gun can be ensured, and the denitration efficiency is improved.
In some embodiments of the utility model, the desalting water tank is made of 304 stainless steel, and is provided with a manhole, a breather valve, a material inlet and outlet, an overflow port, an evacuation port, a liquid level measuring port and a climbing ladder.
In some embodiments of the utility model, the metering and mixing unit further comprises an electromagnetic flowmeter electrically operated regulator valve for controlling and regulating the desired ammonia concentration. Specifically, the mixing proportion of desalted water and ammonia water is controlled through an electromagnetic flowmeter and an electric regulating valve, so that the purpose of controlling the concentration of ammonia water is achieved.
In some embodiments of the utility model, an electric regulating valve, an electromagnetic flowmeter and a pressure gauge are arranged on the dilute ammonia water pipeline; the electric regulating valve is used for controlling the input and the cutting of the dilute ammonia water; the electric regulating valve and the electromagnetic flowmeter are used together for controlling and observing the flow of the double-fluid atomization spray gun connected with the pipeline, so that the accurate control of the flow of the spray gun is realized; the compressed air pipeline is provided with a pressure reducing valve and a pressure gauge.
The fine distribution unit is internally provided with a dilute ammonia water pipeline and a compressed air pipeline of each spray gun, and each dilute ammonia water pipeline is also provided with a manual ball valve, a check valve and other elements. When the dual fluid atomizing spray gun in the atomizing spray unit is withdrawn and in use, the remote dilute ammonia water input and removal are realized by controlling the opening degree of an electric regulating valve in the fine distribution unit. Meanwhile, the flow of each double-fluid atomizing spray gun can be remotely controlled and observed through the electric regulating valve and the electromagnetic flowmeter, so that the flow of each double-fluid atomizing spray gun can be accurately controlled, the ammonia consumption is integrally reduced on the premise of ensuring the denitration efficiency, and the ammonia can escape in a controllable range.
Meanwhile, the fine distribution units are determined according to the number of the atomizing and spraying unit partitions, the flow of each spray gun can be accurately measured, the fine distribution units in each region can be cut off and put into use at any time according to the operation conditions, and the degree of automation is high.
In some embodiments of the present utility model, the atomizing spray unit uses a fixed two-fluid atomizing spray gun, and each spray gun needs to be provided with a compressed air pipe at the same time to provide compressed air required by full atomization of the ammonia solution and spray gun cooling air. The ammonia water solution atomized by the spray gun is uniformly mixed with the flue gas in the flue, and is fully mixed with NO in the flue gas x Reaction takes place to remove NO in the flue gas x 。
The denitration spray gun is required to be specially designed, a reducing agent (namely dilute ammonia water) is atomized and sprayed into the flue gas at a certain angle, speed and direction, specific control parameters are different according to different boilers and types of the reducing agent, and CFD numerical simulation is required to assist in optimizing design determination in the design process. The larger the boiler, the smaller the mixing degree of the sprayed ammonia water and the flue gas will be due to the influence of the size of the boiler and the flue gas flow state. In order to achieve a good mixing of the aqueous ammonia solution with the flue gas in the furnace, a specially designed stationary two-fluid atomizing spray gun is used to atomize the aqueous ammonia solution to obtain an optimal droplet size and distribution. The evaporation time and the running track of the liquid drop are in a function relation with the diameter of the liquid drop, and the liquid drop with large diameter has large momentum and thus strong penetrating capacity, but long evaporation time is required at the same time, so that the required residence time is increased.
Further, the structural form of the denitration spray gun is determined according to the position of the denitration spray gun, and for a circulating fluidized bed boiler, the spray gun arranged in a boiler furnace is generally of a narrow-angle solid cone structure, and the spray gun arranged at the inlet of a horizontal flue of a cyclone separator is of a wide-angle fan shape. The spray gun with the narrow-angle solid cone structure has farther range than the wide-angle fan-shaped spray gun, stronger penetrating power and high speed of 50-60m/s when the water mist is sprayed out from the nozzle outlet, thereby ensuring that the reducing agent can be fully mixed with the flue gas and further improving the denitration efficiency. The inlet of the cyclone separator is a narrow flue section, wide-angle fan-shaped staggered opposite spraying is adopted, and the fan-shaped surface is perpendicular to the flow direction of the flue gas, so that the flue gas denitration reaction is facilitated.
At the same time, according to different working conditions (such as boiler type, temperature field in furnace, original NO) X The concentration of the spray gun, the insertion position and depth of the spray gun, etc.), the flow rate and the atomized particle diameter of the spray gun are calculated and designed, the flow rate of the spray gun is varied from 5kg/h to 500kg/h, and the average atomized particle diameter is varied from 50 microns to 200 microns.
In some embodiments of the present utility model, zone control is generally performed in order to increase SNCR denitration efficiency, reduce the level of ammonia slip, and consider increasing the number of denitration spray gun zones; the optimal temperature window of the SNCR denitration process is 850-1050 ℃, and due to the limitation of a reaction temperature window, the reducing agent needs to be sprayed into a proper position in the furnace, and the flue gas temperature in the radiation heating surface and convection heating surface areas can meet the requirement. Tapping and spraying the reducing agent at the correct furnace wall location means that a high denitration efficiency can be obtained. Preferably, the arrangement and the installation position of the spray gun need to be analyzed to know the NO of the hearth x And finally determining concentration distribution, hearth temperature distribution, hearth airflow distribution and smoke component distribution.
Therefore, the two-fluid atomization spray guns are arranged in a partitioned mode, and the two-fluid atomization spray guns are arranged at the positions of boiler walls with the flue gas temperature of 850-1050 ℃. Preferably, holes are arranged on the boiler wall with the temperature of the flue gas of 850-1050 ℃, and the double-fluid atomization spray gun sprays dilute ammonia water into the flue gas through the holes.
In some embodiments of the utility model, the number of partitions of the spray gun varies according to the form and structure of the boiler, and for circulating fluidized bed boilers, the dual fluid atomizing spray gun is generally arranged in three regions, one region is arranged in the boiler furnace, the second region is arranged at the inlet of the horizontal flue of the cyclone separator, and the third region is arranged at the outlet of the central cylinder of the cyclone separator; the two-fluid atomizing spray guns in each zone are individually controlled by a fine distribution unit. The zoned arrangement is adopted, so that the residence time of the ammonia water in the reactor is increased, the flue gas and the ammonia water are mixed more fully, and the utilization rate of the ammonia is improved.
In some embodiments of the present utility model, the SNCR ammonia injection fine adjustment and control deep denitration system further includes a control unit, configured to control the concentration of the diluted ammonia water in the metering and mixing unit, control the input and the removal of each diluted ammonia water pipeline in the fine distribution unit, and the flow of the dual-fluid atomizing spray gun corresponding to each diluted ammonia water pipeline, and simultaneously, operate the corresponding dual-fluid atomizing spray gun according to feedback of the temperature detection device, so as to implement automatic operation of the system.
The beneficial effects of the utility model are as follows:
the utility model discloses an SNCR ammonia spraying fine regulation and control deep denitration system. Three factors affecting SNCR denitration efficiency are respectively: the optimal reaction temperature window, the residence time of the ammonia water and the mixing degree of the ammonia water and the flue gas. According to the utility model, the ultra-high fine atomization spray guns are arranged in a partitioning manner, so that compared with the traditional common SNCR denitration, the spray area is increased, and when sprayed ammonia leaves the boiler along with flue gas, all the technological processes are completed, and the method comprises the following steps: mixing the sprayed ammonia solution with the flue gas, evaporating water, decomposing ammonia gas by ammonia water molecules into NH 2 And free active molecules, NO x And (3) reduction reaction. In addition, temperature measuring points are arranged on the spray guns in each area, so that when the boiler runs under different loads, the corresponding spray guns can be put into operation according to feedback of the temperature measuring points, and ammonia consumption is reduced on the premise of ensuring denitration efficiency, so that ammonia escape is controlled.
In order to facilitate processing and installation and ensure processing quality, each unit of the SNCR ammonia injection fine regulation and control deep denitration system can be designed, processed and installed respectively, so that the on-site installation time is saved, and the production and processing quality is ensured.
Drawings
The accompanying drawings, which are included to provide a further understanding of the utility model and are incorporated in and constitute a part of this specification, illustrate embodiments of the utility model and together with the description serve to explain the utility model.
Fig. 1 is a schematic structural diagram of an SNCR ammonia injection fine control depth denitration system according to embodiment 1 of the present utility model.
Wherein, 1: an ammonia discharging pump; 2: a 20% ammonia storage tank; 3: an ammonia water delivery pump; 4: a desalting water tank; 5: a demineralized water delivery pump; 6: a metering and mixing unit; 701: a fine distribution unit 1 section; 702: a fine distribution unit 2 area; 703: a fine distribution unit 3 area; 704: a dilute ammonia pipeline; 705: a compressed air line; 801: an atomizing and spraying unit 1 area; 802: an atomizing and spraying unit 2 area; 803: an atomizing and spraying unit 3 area; 804: a dual fluid atomizing spray gun; 9: ammonia absorption barrel.
Detailed Description
In order to enable those skilled in the art to more clearly understand the technical scheme of the present utility model, the technical scheme of the present utility model will be described in detail with reference to specific embodiments.
Example 1
As shown in fig. 1, an SNCR ammonia injection fine control depth denitration system includes: an ammonia discharging pump 1, a 20% ammonia water storage tank 2, an ammonia water delivery pump 3, a desalted water tank 4, a desalted water delivery pump 5, a metering and mixing unit 6, a fine distribution unit 1 area 701, a fine distribution unit 2 area 702, a fine distribution unit 3 area 703, a dilute ammonia water pipeline 704, a compressed air pipeline 705, an atomization injection unit 1 area 801, an atomization injection unit 2 area 802, an atomization injection unit 3 area 803, a two-fluid atomization spray gun 804 and an absorption barrel 9.
The inlet of the ammonia discharging pump 1 is connected with an ammonia tank truck, and the outlet of the ammonia discharging pump 1 is connected with a 20% ammonia storage tank 2; the outlet of the 20% ammonia water storage tank 2 is connected with the inlet of the ammonia water delivery pump 3, and the outlet of the ammonia water delivery pump 3 is connected with the inlet of the metering mixing unit 6. The inlet of the desalting water tank 4 is connected with a factory desalting mother pipe, the outlet of the desalting water tank 4 is connected with the inlet of the desalting water delivery pump 5, and the outlet of the desalting water delivery pump 5 is connected with the inlet of the metering mixing unit 6. The outlet of the metering and mixing unit 6 is connected with the inlet of a dilute ammonia pipeline 704 of the fine distribution unit, the outlet of the dilute ammonia pipeline 704 is connected with the inlet of a double-fluid atomizing spray gun 804 of the ultra-high fine atomizing spray unit, and the outlet of the double-fluid atomizing spray gun 804 is connected with a boiler.
The ammonia water is easy to volatilize out ammonia, and the volatilization rate is increased along with the temperature rise and the placement time extension, so the top of the 20% ammonia water storage tank 2 is provided with an ammonia absorption barrel 9 for absorbing volatilized ammonia. Meanwhile, an ammonia leakage detector is arranged around the 20% ammonia water storage tank 2 to prevent ammonia from volatilizing and leaking.
The outlet of the ammonia water delivery pump 3 is provided with an electric regulating valve group, and the opening degree of the electric regulating valve is used for controlling the pressure of the delivery pump outlet to be a stable value, and the pressure is generally controlled to be about 1.0 Mpa. Only under the premise that the pressure and the flow on the pipeline are stable and controllable, the ultra-high atomization effect of the double-fluid atomization spray gun can be ensured, and the denitration efficiency is improved.
The desalting water tank 4 is provided with a magnetic flap liquid level meter, the liquid level meter is controlled in linkage with an electric switch valve for water inflow of a desalting water main pipe, and when the liquid level is lower than a low set value, water is automatically replenished; when the liquid level is higher than the high set value, water supplementing is stopped, and automatic control is realized. Meanwhile, an electric regulating valve group is arranged at the outlet of the desalted water conveying pump 5, and the opening degree of the electric regulating valve is used for controlling the pressure of the conveying pump outlet to be a stable value, and the pressure is generally controlled to be about 1.0 Mpa. Only under the premise that the pressure and the flow on the pipeline are stable and controllable, the ultra-high atomization effect of the double-fluid atomization spray gun can be ensured, and the denitration efficiency is improved.
The metering and mixing unit 6 mainly dilutes 20% of concentrated ammonia water solution into dilute ammonia water with concentration of 5% -8% in a mixer through desalted water, and the quantity of the required 20% ammonia water is controlled by a flowmeter and regulated by an electric regulating valve. The required amount of dilution water is controlled by a flowmeter before being mixed with the strong ammonia water, and an electric regulating valve is used for regulating the dilution water to ensure that the strong ammonia water with the concentration of 20 percent can be diluted into the weak ammonia water with the concentration of 5 to 8 percent.
The diluted dilute ammonia water is precisely metered and regulated by a flowmeter control and electric regulating valve in the fine distributing unit, and then is sprayed into a hearth through a double-fluid atomizing spray gun 804 to participate in denitration reaction. Thus, the flow of each spray gun can be controlled and detected on line in real time, and the ammonia water can be saved.
For a circulating fluidized bed boiler, the atomizing and spraying units are arranged in a partition mode, namely an atomizing and spraying unit 1 area 801, an atomizing and spraying unit 2 area 802 and an atomizing and spraying unit 3 area 803. The first area is arranged in a boiler hearth, the second area is arranged at the inlet of a horizontal flue of the cyclone separator, and the third area is arranged at the outlet of a central cylinder of the cyclone separator; the two-fluid atomizing spray guns in each zone are individually controlled by a fine distribution unit. Each zone is provided with a corresponding temperature measuring point, i.e. a thermocouple. In actual operation of the boiler, the spray guns of each zone are put into operation and cut off through feedback of temperature measuring points. The spray gun adopts a double-fluid fixed wall type spray gun, and the aperture size of the spray gun opening is generally 57mm in diameter. Holes are formed in the boiler wall with the temperature of 850-1050 ℃ of the flue gas, and the double-fluid atomization spray gun sprays dilute ammonia water into the flue gas through the holes.
The control unit of the SNCR ammonia spraying fine regulation depth denitration system generally adopts DCS/PLC, a flue gas online analyzer and an ammonia escape detector are arranged on a boiler tail flue, and the control unit can be used for uploading NO according to the flue gas analyzer x Concentration signals are regulated by flow meter control and electric regulating valve in the fine distribution unit 1 area 701, the fine distribution unit 2 area 702 and the fine distribution unit 3 area 703, so that the addition amount of the ammonia water solution can be automatically controlled, and NO is realized x Is discharged in real time up to the standard.
The reaction of reducing NO by SNCR is very sensitive to temperature conditions, and the selection of injection points on a hearth, namely the selection of a so-called temperature window, is a key of the high and low efficiency of reducing NO by SNCR. The spray gun of the traditional common SNCR denitration technology is not partitioned, and when the boiler is full, the temperature window can meet the requirements. However, when the boiler is started and operated under low load, the optimal denitration temperature is not in the position. In this case, holes are formed in the proper hearth positions and reducing agent is sprayed into the holes, so that high denitration efficiency can be obtained. The SNCR ammonia spraying fine regulation and control deep denitration system adopts multi-point spraying, and is based on NO uploaded by a flue gas analyzer CEMS x The flow of each spray gun can be accurately regulated by the concentration signal, so that the ammonia water solution can be evenly distributed to a plurality of corresponding spray guns, and the spray guns are evenly distributed so as to achieve the purpose of fully and evenly mixing with the flue gas. Meanwhile, according to the feedback of the thermocouple temperatures of the spray gun partition arrangement, the spray guns in each area can be remotely thrown and cut off, so that the method is suitable for denitration ultra-clean emission under any working condition of a boiler. By the mode, stability and efficiency of SNCR denitration are improved, consumption of ammonia water is reduced, ammonia escapes in a controllable range, and running cost is reduced.
The above description is only of the preferred embodiments of the present utility model and is not intended to limit the present utility model, but various modifications and variations can be made to the present utility model by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present utility model should be included in the protection scope of the present utility model.
Claims (10)
1. The SNCR ammonia spraying fine regulation and control deep denitration system is characterized by comprising a reducing agent storage and supply unit, a desalted water unit, a metering and mixing unit, a fine distribution unit and an atomization spraying unit;
the reducing agent storage and supply unit includes: an ammonia water storage tank and an ammonia water delivery pump; the ammonia water conveying pump is used for conveying the ammonia water in the ammonia water storage tank to the metering unit;
the demineralized water unit includes: a desalting water tank and a desalting water conveying pump; the desalted water conveying pump is used for conveying the dilution water in the desalted water tank to the metering unit;
the metering and mixing unit comprises: a mixer for diluting the ammonia water supplied by the ammonia water delivery pump and the desalted water supplied by the desalted water delivery pump into dilute ammonia water with a target concentration in the mixer;
the fine distribution unit includes: a dilute ammonia water pipeline and a compressed air pipeline which are connected with the atomization injection unit; the device is used for conveying the dilute ammonia water in the metering unit to the atomization injection unit through a dilute ammonia water pipeline and conveying the compressed air to the atomization injection unit through a compressed air pipeline;
the atomizing injection unit is used for spraying the atomized dilute ammonia water and compressed air into the flue gas, and comprises: the device comprises a double-fluid atomizing spray gun and a temperature detection device, wherein the temperature detection device is used for detecting the temperature of the double-fluid atomizing spray gun; each double-fluid atomizing spray gun is connected with a dilute ammonia water pipeline and a compressed air pipeline.
2. The SNCR ammonia injection fine control depth denitration system according to claim 1, wherein the reducing agent storage and supply unit further comprises an ammonia water unloading pump for delivering ammonia water in an ammonia water tank truck to an ammonia water storage tank for storage; the ammonia water unloading pump is a multistage centrifugal pump and is made of stainless steel.
3. The SNCR ammonia spraying fine regulation and control depth denitration system according to claim 1, wherein the ammonia water storage tank is made of 304 stainless steel, and a manhole, a breather valve, a material inlet and outlet, an overflow port, an evacuation port, a temperature measurement port, a liquid level measurement port and a ladder stand are arranged on the ammonia water storage tank;
or the ammonia water conveying pump is a multistage centrifugal pump and is made of stainless steel.
4. The SNCR ammonia spraying fine control depth denitration system of claim 1, wherein the desalting water tank is made of 304 stainless steel, and is provided with a manhole, a breather valve, a material inlet and outlet, an overflow port, an emptying port, a liquid level measuring port and a cat ladder.
5. The SNCR ammonia injection fine control depth denitration system according to claim 1, wherein the metering mixing unit further comprises an electromagnetic flowmeter electric regulating valve for controlling and regulating the concentration of the required ammonia water.
6. The SNCR ammonia injection fine regulation and control deep denitration system as claimed in claim 1, wherein an electric regulating valve, an electromagnetic flowmeter and a pressure gauge are arranged on the dilute ammonia water pipeline; the electric regulating valve is used for controlling the input and the cutting of the dilute ammonia water; the electric regulating valve and the electromagnetic flowmeter are used together for controlling and observing the flow of the double-fluid atomization spray gun connected with the pipeline, so that the accurate control of the flow of the spray gun is realized;
the compressed air pipeline is provided with a pressure reducing valve and a pressure gauge.
7. The SNCR ammonia injection fine control depth denitration system as claimed in claim 1, wherein the two-fluid atomization spray guns are arranged in a partitioned mode, and the two-fluid atomization spray guns are arranged at the positions of boiler walls with the flue gas temperature of 850-1050 ℃.
8. The SNCR ammonia spraying fine control depth denitration system as claimed in claim 7, wherein holes are arranged on the boiler wall with the temperature of the flue gas ranging from 850 ℃ to 1050 ℃, and the double-fluid atomizing spray gun sprays dilute ammonia water into the flue gas through the holes.
9. The SNCR ammonia injection fine control depth denitration system as claimed in claim 7, wherein for a circulating fluidized bed boiler, the double-fluid atomization spray gun is arranged in three areas, wherein the first area is arranged in a boiler furnace, the second area is arranged at the inlet of a horizontal flue of a cyclone separator, and the third area is arranged at the outlet of a central cylinder of the cyclone separator; the two-fluid atomizing spray guns in each zone are individually controlled by a fine distribution unit.
10. The SNCR ammonia injection fine control depth denitration system according to any one of claims 1 to 9, further comprising a control unit for controlling the concentration of the dilute ammonia water in the metering and mixing unit, controlling the input and the removal of each dilute ammonia water pipeline in the fine distribution unit and the flow rate of the corresponding double-fluid atomizing spray gun of each dilute ammonia water pipeline, and simultaneously, operating the corresponding double-fluid atomizing spray gun according to feedback of the temperature detection device.
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