A dust removal device and method for SCR ammonia escape measurement instrument in a coal-fired power plant

Abstract

The present invention relates to a dust removal device and method for a coal-fired power plant SCR ammonia escape measurement instrument, and belongs to the technical field of flue gas treatment and energy conservation and emission reduction in coal-fired power plants. At present, due to the adsorption of ammonia by aggregated ash, the problem of poor representativeness of sample gas and poor reliability of ammonia escape rate measurement meters cannot be solved. The present invention includes a sampling and exhaust pipe and an ammonia detection host, and is characterized in that it also includes an air intake connecting pipe, a separation tee, a collecting and distributing ash hopper and a vertical steering pipe. The separation tee is a T-shaped structure, and the three flow ports of the separation tee are respectively connected to the air intake connecting pipe, the collecting and distributing ash hopper and the vertical steering pipe. Among the three flow ports of the separation tee, the axis of the flow port for connecting the air intake connecting pipe and the axis of the flow port for connecting the collecting and distributing ash hopper are in the same direction, and the vertical steering pipe is connected to the other end of the sampling and exhaust pipe. The present invention solves the problem of ash adsorption of ammonia in the sample gas, ensures the authenticity of the sample gas, and improves the accuracy and reliability of ammonia escape rate measurement.

Description

Technical Field

[0001] The invention relates to a dust removal device and method for an SCR ammonia escape measuring instrument of a coal-fired power plant, belonging to the technical field of smoke treatment and energy saving and emission reduction in coal-fired power plants. Background Art

[0002] Most of my country's large and medium-sized coal-fired power plants use selective catalytic reduction (SCR) denitrification technology, and denitrification is achieved through SCR reactors. After the flue gas at the tail of the boiler of a coal-fired power plant comes out of the boiler furnace, it flows through the economizer, SCR reactor, air preheater, electrostatic precipitator and desulfurization device in sequence. In the SCR denitrification system, the ammonia escape rate is one of the important monitoring indicators, because the increase in ammonia escape rate will cause an increase in the generation of ABS, and the deposition and adhesion in the air preheater will block the air preheater, affecting the safety of boiler operation, increasing the power consumption rate of the plant and increasing the cost of denitrification. Therefore, during the operation of the SCR denitrification system, it is necessary to strengthen the detection of ammonia escape rate, adjust the supply of ammonia in time, maintain a normal molar ratio, and control the ammonia escape rate to less than 3ppm while ensuring the denitrification efficiency.

[0003] At present, the main difficulty in measuring the ammonia escape rate of SCR denitrification in coal-fired power plants is that the flue gas is in a state of "three highs" of high temperature, high dust and high moisture content; and NH 3 Hydrophilicity and strong adsorption, and high SO 2 Measure low concentrations of NH in a concentrated environment 3 Currently, the measurement of fugitive NH in flue gas is 3 The concentration of NH 3 The concentration is usually 1-2ppm, and the range of the instrument is selected as 0-10ppm.

[0004] NH 3 There are two main types of analyzers: the first is laser NH 3 The analyzer is a direct measurement method that does not require sampling, but its optical path length is limited and can overcome dust interference within a certain range. Its principle is based on NH 3 The absorption of a specific laser spectrum is not affected by other gas components due to the narrow laser bandwidth. The measured value is greatly affected by the flow field distribution of the flue. If the flow field is uneven, the measurement accuracy is not high. To overcome the problem of uneven flow field, the length of the measurement optical path should be extended as much as possible, a sampling fan should be set up, multiple points of the outlet flue should be sampled, and a pipe section should be installed on the air duct to install NH 3 The advantages are reliable and representative sampling and high reliability of measured values; the disadvantages are that the fan runs continuously under high temperature and high dust conditions, its life is short and its reliability is poor. 3 The basic principle of the analyzer is NO and O3 The reaction produces fluorescence and can simultaneously measure NO X , by calculating NH 3 For environments with high smoke concentration (such as greater than 40g / Nm 3 ), then this measurement method has advantages. The sampling method is the dilution method. Since ammonia is easily soluble, it cannot be pre-treated by heating and rapid condensation. There are problems such as measuring conversion efficiency, dust blocking the sampling tube, and the absorption of trace ammonia by moisture and the adsorption of ammonia by ash during sampling and transmission, which affect the measurement accuracy.

[0005] Therefore, the ammonia escape rate measuring instrument is required to have the characteristics of high sensitivity, low measurement range, strong operability, reliable operation, and convenient maintenance and calibration under the "three highs" environment. Since the ammonia escape rate instrument has poor operation effect, its measurement data does not meet the operation and reference requirements of the power plant. The power plant generally still controls the ammonia injection amount through NO emission data; when the denitrification device fails, such as catalyst aging, ash blockage, poisoning, uneven distribution of nitrogen oxides and ammonia in the flue gas, etc., at this time, even if the NO emission meets the requirements, the ammonia escape rate may be very large.

[0006] There are also technologies related to flue gas monitoring. For example, a Chinese patent with a publication date of March 12, 2019 and a publication number of CN208596072U discloses a dust filter device and a flue gas analyzer. When the dust filter device is in use, the flue gas enters one end of the dust filter device and exits the other end. Before the flue gas is passed, the two ends of the inner filter cloth tube are twisted relative to each other to twist the barrel of the inner filter cloth tube to form a closed filter surface. After that, the flue gas is passed and the filter surface filters the flue gas. Another example is a Chinese patent with a publication date of March 22, 2017 and a publication number of CN106525522A, which discloses an ammonia escape sampling device with a self-cleaning system. The ammonia escape sampling device uses the dust filter cover on the sampling gun to filter dust, and dust is removed by backblowing with an air pump. For example, a Chinese patent with a publication date of June 14, 2019 and publication number CN109876575A discloses a smoke filter and a smoke and flue gas sampling device. Although the primary filter chamber separates the smoke by the inertia of the particles, the large particle droplets and large particle dust after separation are accumulated on the baffle.

[0007] In response to the above problems, when monitoring the ammonia escape rate of flue gas in coal-fired power plants, laser NH 3 The analyzer is usually installed at an angle in the flue, and the uniformity of the flue gas flow field cannot be guaranteed. 3 Analyzer and external laser NH 3The analyzer contains high concentrations of particulate matter in the sample gas. The primary filter on the sampling probe prevents the particulate matter from entering the sample gas pipeline. The automatic backflush controller can periodically backflush the filter inside the sample gas pipeline to prevent smoke from blocking the filter. However, due to the adsorption of ammonia by the accumulated ash, the problem of poor representativeness of the sample gas and poor reliability of the ammonia escape rate measurement meter cannot be solved. Summary of the invention

[0008] The purpose of the present invention is to overcome the above-mentioned deficiencies in the prior art and to provide a dust removal device and method for the SCR ammonia escape measuring instrument in a coal-fired power plant which has a reasonable design, solves the problem of ash adsorption of ammonia in the sample gas, ensures the authenticity of the sample gas, and improves the accuracy and reliability of the measurement of the ammonia escape rate.

[0009] The technical solution adopted by the present invention to solve the above-mentioned problem is: the dust removal device of the SCR ammonia escape measuring instrument of the coal-fired power plant includes a sampling exhaust pipe and an ammonia detection host, the sampling exhaust pipe is connected to the flue, one end of the sampling exhaust pipe is located outside the flue, and the other end of the sampling exhaust pipe is located in the flue, the ammonia detection host is located outside the flue, and the ammonia detection host is connected to one end of the sampling exhaust pipe, and its structural characteristics are: it also includes an air intake connecting pipe, a separation tee, a collecting and distributing ash hopper and a vertical steering pipe, the separation tee is a T-shaped structure, and the three flow ports of the separation tee are respectively connected to the air intake connecting pipe, the collecting and distributing ash hopper and the vertical steering pipe, among the three flow ports of the separation tee, the axis of the flow port for connecting the air intake connecting pipe and the axis of the flow port for connecting the collecting and distributing ash hopper are in the same direction, and the vertical steering pipe is connected to the other end of the sampling exhaust pipe.

[0010] Preferably, the present invention further comprises an air intake pipe, wherein the air intake pipe is connected between the air intake connecting pipe and the separation tee.

[0011] Preferably, a transition section is provided at the connection between the collecting and distributing ash hopper and the separation tee of the present invention, and the distance between the top of the transition section and the lower wall of the air inlet pipe is d, and d satisfies 0≤d≤5a 1 , a 1 is the diameter of the air intake connecting pipe, and the angle α between the transition section and the vertical steering pipe satisfies 0°≤α<90°.

[0012] Preferably, the lower portion of the collecting and distributing ash hopper of the present invention is a dust discharge port, and the dust discharge port is wedge-shaped, and the dust discharge port forms an angle γ, and the angle γ satisfies 0°≤γ≤75°.

[0013] Preferably, the diameter a of the sampling air extraction pipe of the present invention is 2 Meets 0.3a 1 ≤a 2 ≤3a 1 , a 1 is the diameter of the intake connecting pipe.

[0014] Preferably, the vertical steering tube of the present invention is composed of a vertical section, a curved section and a horizontal section connected in sequence, and the curvature radius r of the curved section is 1 Satisfy 1 ≥ 3 years 2 , a 2 is the diameter of the vertical steering tube.

[0015] Preferably, the air inlet of the air inlet connecting pipe of the present invention is a 90° elbow structure.

[0016] Preferably, the ash collecting and distributing hopper of the present invention is in the shape of a cone horn, the cone bottom angle θ satisfies 0°≤θ<90°, and the cone bottom diameter D satisfies a 1 ≤D≤10a 1 , a 1 is the diameter of the intake connecting pipe.

[0017] A method for removing dust from SCR ammonia escape measuring instruments in coal-fired power plants, characterized in that: using the dust removal device for SCR ammonia escape measuring instruments in coal-fired power plants, the method for removing dust from SCR ammonia escape measuring instruments in coal-fired power plants is as follows: the dust removal device for SCR ammonia escape measuring instruments in coal-fired power plants is incorporated into the flue gas sampling port of the flue gas measuring instrument to remove most of the dust in the flue gas, avoid dust accumulation on the dust removal filter of the suction contact measuring device to adsorb the escaped ammonia in the sample gas, thereby improving the representativeness of the sample gas, or for the suction external spectral test instrument, the problem of poor representativeness of the sample gas is also solved; the dust removal device for SCR ammonia escape measuring instruments in coal-fired power plants is located at the sampling probe The head and the sampling tube are arranged together with the sampling probe in the measured flue, the collecting and distributing ash hopper is connected in series with the rear end of the steering sampling tube side and is parallel to it, the dust removal unit and the collecting and distributing ash hopper are arranged in an integrated manner, and the ash removed by the dust removal unit passes through the lower collecting and distributing ash hopper and is returned to the flue; the dust removal unit includes a special-shaped expansion and contraction port, a tail impact plate and at least two side plates, forming a special-shaped structural box body, the opening of the special-shaped structural box body is parallel to the flue gas inflow direction, and the opening of the special-shaped structural box body forms an angle of 0-75° with the flue gas inflow direction, so that the dust exhaust port is in a leeward state, so as to smoothly return the ash collected by the dust removal unit to the flue without being affected by the secondary suction of the flue gas and affecting the ash exhaust.

[0018] Preferably, the average flow velocity of the flue gas flowing through the air intake connecting pipe and the sampling exhaust pipe is not less than 3 m / s to avoid dust deposition in the pipeline; the diameter of the air intake connecting pipe is a 1 and the diameter of the sampling air extraction pipe a 2 Not less than 3mm and not more than 30mm.

[0019] Compared with the prior art, the present invention has the following advantages and effects: below the ash collecting and distributing hopper is a wind shield cone at a certain angle along the direction of the flue gas velocity, so that the collected ash can be smoothly sent back to the original flue without being affected by the secondary entrainment of the flue gas and affecting the ash discharge. Compared with the prior art sample gas mesh filter device, it is not easy to be blocked by ash, because the fly ash will move downward and fall into the ash collecting and distributing hopper under its own gravity and the effect of part of the flue gas carrying, and the fly ash is not easy to adhere to the dust removal unit, so it is not easy to be blocked by ash, and the ash is sent back to the original flue after being collected. Below the ash collecting and distributing hopper is a certain angle along the incoming direction of the flue gas, and the angle γ satisfies 0°≤γ≤75°. The dust discharge port is in a "leeward" state, and the collected ash can be smoothly sent back to the original flue without being affected by the secondary entrainment of the flue gas and affecting the ash discharge. It can prevent the captured fly ash from being entrained into the sample gas again, and ensure that the sample gas sucked by the sampling tube is clean flue gas after the removal. The present invention has a simple structure and compact space, and can prevent coarser fly ash with a particle size of more than 20 μm from entering the flue gas sampling tube, avoiding dust accumulation on the dust filter of the suction contact type and suction external type spectrum test instrument measurement device to adsorb ammonia escaping from the sample gas, and effectively solves the problem of ash adsorption of ammonia in the sample gas, ensuring the authenticity of the sample gas, and improving the accuracy and reliability of ammonia escape rate measurement. By monitoring the ammonia escape rate, it is possible to correctly determine whether the denitrification device has a fault, which helps to detect problems early and make timely adjustments; it provides support for real-time online and accurate measurement of ammonia escape rate, changing the extensive ammonia spraying mode, and realizing refined ammonia spraying.

[0020] The collecting and distributing ash hopper can be connected in series with the rear end of the steering sampling tube and parallel to it. The dust removal unit can be arranged in an integrated manner with the collecting and distributing ash hopper. The side plate can be a rectangular or arc-shaped structure. The ash removed by the dust removal unit passes through the lower collecting and distributing ash hopper and is returned to the original flue. A wind shield cone is formed at a certain angle along the flue gas flow direction below the collecting and distributing ash hopper. The dust removal unit can include a special-shaped expansion port, a tail impact plate and at least two side plates to form a special-shaped structural box body. The opening of the special-shaped structural box body is parallel to the flue gas inflow direction. The wind shield cone is located at the opening of the box body and forms a certain angle with the flue gas flow direction, so that the ash collected by the dust removal unit is smoothly returned to the original flue without being sucked by the flue gas for the second time to affect the ash removal effect. The dust removal unit includes a special-shaped expansion port, a tail impact plate, at least two side plates, and a special-shaped structural box body composed of a wind shield cone. The opening of the special-shaped box is parallel to the direction of flue gas inflow. Below the collecting and distributing ash hopper, it forms a certain angle along the direction of flue gas flow. The angle γ satisfies 0°≤γ≤75°. The dust discharge port is in a "leeward" state to smoothly send the ash collected by the dust removal unit back to the original flue without being affected by the secondary entrainment of the flue gas. Among them, the deformed expansion port of the special-shaped box has a uniform structure parallel to the flue gas flow direction at the upper part of the connecting pipe, and the angle α at the lower part with the horizontal direction is 0°≤α<90°. The projection length of this oblique line is 2a 1 (a 1 is the diameter of the air inlet connecting pipe); the length c of the special-shaped box of the dust removal unit is 3a 1 -4a 1, the ratio of the depth a to the width b of the special-shaped box is 1≤a / b≤5, and the width b of the dust removal unit is a 1 .

[0021] The sampling port and the measuring unit tube can be threaded and movably connected to the dust removal unit. The sampling port can be replaced as needed to meet the sampling requirements and to change the connection position and direction. The movably connected sampling tube and the sampling vertical steering tube can be anti-wear treated, and the special-shaped structure box can be Hastelloy. The dust removal device for measuring the ammonia escape rate of SCR denitration in coal-fired power plants can change the size structure of the dust removal device and the size of the special-shaped scaling port and the tail impact plate according to the changes in the dust particles in the sampled flue gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of the dust removal device of the SCR ammonia escape measuring instrument of a coal-fired power plant in Example 1 of the present invention.

[0023] Figure 2 It is a structural schematic diagram of the dust removal device of the SCR ammonia escape measuring instrument of a coal-fired power plant in Example 2 of the present invention.

[0024] Figure 3 It is a schematic structural diagram of the air inlet of the air inlet connecting pipe with a 90° elbow structure in Example 2 of the present invention.

[0025] Figure 4 It is a structural schematic diagram of the dust removal device of the SCR ammonia escape measuring instrument of a coal-fired power plant in Example 3 of the present invention.

[0026] In the figure: air intake connecting pipe 1, separation tee 2, collecting and dispersing ash hopper 3, vertical turning pipe 4, flue 5, air intake pipe 6, sampling air extraction pipe 7, air inlet 1-1, dust exhaust port 3-1, transition section 3-2, vertical section 4-1, elbow section 4-2, horizontal section 4-3. DETAILED DESCRIPTION

[0027] The present invention will be further described in detail below with reference to the accompanying drawings and by way of examples. The following examples are intended to explain the present invention but the present invention is not limited to the following examples.

[0028] Example 1.

[0029] like Figure 1 As shown, the dust removal device of the SCR ammonia escape measuring instrument of the coal-fired power plant in this embodiment includes an air intake connecting pipe 1, a separation tee 2, a collecting and distributing ash hopper 3, a vertical turning pipe 4, a horizontal flue 5, an air intake pipe 6, a sampling air extraction pipe 7, and an ammonia (flue gas) detection host (not shown in the figure). The sampling air extraction pipe 7 is connected to the flue 5, one end of the sampling air extraction pipe 7 is located outside the flue 5, and the other end of the sampling air extraction pipe 7 is located inside the flue 5. The ammonia detection host is located outside the flue 5, and the ammonia detection host is connected to one end of the sampling air extraction pipe 7.

[0030] The sampling exhaust pipe 7 is connected to the ammonia (flue gas) detection host outside the flue 5. The sampling exhaust pipe 7 has a certain negative pressure, so that the flue gas can be sucked from the flue gas through the air intake connecting pipe 1. The air inlet 1-1 of the air intake connecting pipe 1 directly faces the incoming direction of the flue gas, and the sucked flue gas flows to the separation tee 2 for dust separation. The three flow ports of the separation tee 2 are respectively connected to the air intake pipe 6, the vertical steering pipe 4 and the collecting and distributing ash hopper 3. The separation tee 2 is a T-shaped structure. Among the three flow ports of the separation tee 2, the axis of the flow port for connecting the air intake pipe 6 and the axis of the flow port for connecting the collecting and distributing ash hopper 3 are in the same direction.

[0031] When the flue gas containing dust flows through the separation tee 2, most of the flue gas flows directly to the vertical turning pipe 4, while the dust is difficult to follow the flue gas turning due to its large inertia during the process of turning from the air intake pipe 6 to the vertical turning pipe 4, and is thrown into the collecting and distributing ash hopper 3. A transition section 3-2 is provided at the connection between the collecting and distributing ash hopper 3 and the separation tee 2. The distance between the top of the transition section 3-2 and the lower wall of the air intake pipe 6 is d, and d satisfies 0≤d≤5a. 1 , a 1 is the diameter of the air intake connecting pipe 1. The included angle α between the transition section 3-2 and the vertical steering pipe 4 satisfies 0°≤α<90°.

[0032] The dust entering the collecting and distributing hopper 3 from the separation tee 2 moves downward under the combined action of gravity and gas drag, and is discharged into the mainstream flue gas through the dust discharge port 3-1. The lower opening of the collecting and distributing hopper 3 is wedge-shaped, that is, the dust discharge port 3-1 forms a certain angle γ with the flue gas flow direction, and the angle γ satisfies 0°≤γ≤75°, so that the dust discharge port 3-1 is in a "leeward" state, and the ash collected by the dust removal unit can be smoothly sent back to the original flue 5 without being affected by the secondary entrainment of the flue gas and affecting the ash discharge, and the collected fly ash can be prevented from being entrained into the sample gas again. The diameter a of the vertical turning pipe 4 2 Meets 0.3a 1 ≤a 2 ≤3a 1 The diameter of the sampling exhaust pipe 7 is the same as the diameter of the vertical steering pipe 4.

[0033] Example 2.

[0034] like Figure 2 and Figure 3As shown, the dust removal device of the SCR ammonia escape measuring instrument of the coal-fired power plant in this embodiment includes an air intake connecting pipe 1, a separation tee 2, a collecting and distributing ash hopper 3, a vertical turning pipe 4, a horizontal flue 5, an air intake pipe 6, a sampling air extraction pipe 7, and an ammonia (flue gas) detection host (not shown in the figure). The sampling air extraction pipe 7 is connected to the flue 5, one end of the sampling air extraction pipe 7 is located outside the flue 5, and the other end of the sampling air extraction pipe 7 is located inside the flue 5. The ammonia detection host is located outside the flue 5, and the ammonia detection host is connected to one end of the sampling air extraction pipe 7.

[0035] The sampling exhaust pipe 7 is connected to the ammonia (flue gas) detection host outside the flue 5. The sampling exhaust pipe 7 has a certain negative pressure, so that the flue gas can be sucked from the flue 5 through the air intake connecting pipe 1. The flue gas sucked from the air intake connecting pipe 1 flows to the separation tee 2 for dust separation.

[0036] The separation tee 2 is a T-shaped structure, and the three flow openings of the separation tee 2 are respectively connected to the air inlet pipe 6, the collecting and distributing hopper 3 and the vertical steering pipe 4. Among the three flow openings of the separation tee 2, the axis of the flow opening for connecting the air inlet pipe 6 and the axis of the flow opening for connecting the collecting and distributing hopper 3 are in the same direction. When the flue gas containing dust flows through the separation tee 2, most of the flue gas flows directly to the vertical steering pipe 4, and in the process of the dust turning from the air inlet pipe 6 to the vertical steering pipe 4 with the flue gas, it is difficult to follow the flue gas turning due to its large inertia, and is thrown into the collecting and distributing hopper 3. A transition section 3-2 is provided at the connection between the collecting and distributing hopper 3 and the separation tee 2, and the distance between the top of the transition section 3-2 and the lower wall of the air inlet pipe 6 is d, and d satisfies 0≤d≤5a 1 , a 1 is the diameter of the air intake connecting pipe 1, and the included angle α between the transition section 3-2 and the vertical steering pipe 4 satisfies 0°≤α<90°.

[0037] The dust entering the collecting and distributing hopper 3 from the separation tee 2 moves downward under the combined action of gravity and gas drag and is discharged into the mainstream flue gas through the dust discharge port 3-1. 2 Meets 0.3a 1 ≤a 2 ≤3a 1 The vertical steering tube 4 is composed of a vertical section 4-1, a curved tube 4-2 and a horizontal section 4-3 connected in sequence. The curvature radius of the curved tube 4-2 is r 1 Satisfy 1 ≥ 3 years 2 .

[0038] The air inlet 1-1 of the air inlet connecting pipe 1 can also be Figure 3 In the 90° elbow form shown, the air inlet 1-1 of the air inlet connecting pipe 1 will directly face the incoming direction of the flue gas.

[0039] Example 3.

[0040] like Figure 4 As shown, the dust removal device of the SCR ammonia escape measuring instrument of the coal-fired power plant in this embodiment includes an air intake connecting pipe 1, a separation tee 2, a collecting and distributing ash hopper 3, a vertical turning pipe 4, a vertical flue 5, a sampling exhaust pipe 7, and an ammonia (flue gas) detection host (not shown in the figure). The sampling exhaust pipe 7 is connected to the flue 5, one end of the sampling exhaust pipe 7 is located outside the flue 5, and the other end of the sampling exhaust pipe 7 is located inside the flue 5. The ammonia detection host is located outside the flue 5, and the ammonia detection host is connected to one end of the sampling exhaust pipe 7.

[0041] The sampling exhaust pipe 7 is connected to the ammonia (flue gas) detection host outside the flue 5. The sampling exhaust pipe 7 has a certain negative pressure, so that the flue gas can be sucked in from the flue gas through the air intake connecting pipe 1. The air intake port 1-1 is directly facing the direction of the flue gas flow. The flue gas sucked in from the air intake connecting pipe 1 flows to the separation tee 2 for dust separation.

[0042] The three flow openings of the separation tee 2 are respectively connected to the air intake connecting pipe 1, the vertical steering pipe 4 and the collecting and distributing ash hopper 3. The separation tee 2 is a T-shaped structure, and among the three flow openings of the separation tee 2, the axis of the flow opening for connecting the air intake connecting pipe 1 and the axis of the flow opening for connecting the collecting and distributing ash hopper 3 are in the same direction.

[0043] When the flue gas containing dust flows through the separation tee 2, most of the flue gas flows directly to the vertical turning pipe 4, while the dust is difficult to follow the flue gas turning due to its large inertia during the process of the flue gas turning from the air intake connecting pipe 1 to the vertical turning pipe 4, and is thrown into the collecting and distributing ash hopper 3. The collecting and distributing ash hopper 3 is in the shape of a cone trumpet, and the cone bottom angle θ satisfies 0°≤θ<90°, and the cone bottom diameter D satisfies a 1 ≤D≤10a 1 The dust entering the collecting and distributing hopper 3 from the separation tee 2 moves downward under the combined action of gravity and gas drag and is discharged into the mainstream flue gas through the dust discharge port 3-1. 2 Meets 0.3a 1 ≤a 2 ≤3a 1 , a 1 is the diameter of the intake connecting pipe 1.

[0044] In the present invention, the average flow velocity of the flue gas flowing through the air intake connecting pipe 1 and the vertical turning pipe 4 should be guaranteed to be no less than 3m / s to avoid dust deposition in the pipeline. 1 and the diameter a of the vertical steering tube 4 2It should be no less than 3mm and no more than 30mm. When a single device of the present invention cannot achieve a sufficiently large air extraction flow rate, multiple identical devices can be used in parallel. The present invention has a simple structure and compact space, and can prevent coarser fly ash with a particle size of more than 20μm from entering the flue gas sampling tube, so that the sample gas sucked by the sampling tube is clean flue gas after deashing, which meets the authenticity and representativeness of the instrument sampling flue gas.

[0045] The present invention solves the current problem of large deviation and low reliability in the measurement of ammonia escape rate in SCR denitration, and the inability to truly reflect ammonia escape. The present invention is installed at the front end of the flue gas sampling suction tube to remove high-concentration particulate matter in the sample gas, and replaces the primary filter (filter screen, etc.) on the sampling probe to prevent particulate matter from entering the sample gas pipeline. While avoiding dust particles from clogging the sampling tube, there is no accumulation of ash at the flue gas filter (filter screen), which well solves the problem of ash adsorption of ammonia in the sample gas, ensures the authenticity of the sample gas, and improves the accuracy and reliability of ammonia escape rate measurement. It provides support for real-time online and accurate measurement of ammonia escape rate, changing the extensive ammonia spray mode, and realizing refined ammonia spray. It can also be used for sample gas dust removal of other suction contact flue gas measurement instruments.

[0046] The present invention may also include a dust removal unit, which is a special-shaped box body, including a special-shaped expansion port, a rear impact plate and at least two side plates, and a wind shield cone. After the flue gas is introduced into the dust removal unit through the special-shaped expansion port, the fly ash in the flue gas will enter the dust removal unit, and collide with the side plates and the impact plate of the dust removal unit for many times, and the speed will be greatly reduced. Under the gravity of the fly ash itself and the carrying effect of the flue gas in the dust removal unit, the fly ash moves downward in the dust removal unit and falls into the ash collecting and distributing hopper 3, and passes through the lower ash collecting and distributing hopper 3 and is returned to the original flue 5. The dust removal unit can capture the fly ash because the opening of the special-shaped box body is parallel to the flue gas inflow direction.

[0047] The above are only preferred specific implementation modes of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and inventive concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A dust removal device for a coal-fired power plant SCR ammonia escape measuring instrument, comprising a sampling air extraction pipe (7) and an ammonia detection host, wherein the sampling air extraction pipe (7) is connected to a flue (5), one end of the sampling air extraction pipe (7) is located outside the flue (5), and the other end of the sampling air extraction pipe (7) is located inside the flue (5), the ammonia detection host is located outside the flue (5), and the ammonia detection host is connected to one end of the sampling air extraction pipe (7), characterized in that: It also includes an air intake connecting pipe (1), a separation tee (2), a collecting and dispersing ash hopper (3) and a vertical steering pipe (4), wherein the separation tee (2) is a T-shaped structure, and the three flow openings of the separation tee (2) are respectively connected to the air intake connecting pipe (1), the collecting and dispersing ash hopper (3) and the vertical steering pipe (4), and the axis of the flow opening for connecting the air intake connecting pipe (1) and the axis of the flow opening for connecting the collecting and dispersing ash hopper (3) are in the same direction, and the vertical steering pipe (4) is connected to the other end of the sampling and exhaust pipe (7); it also includes an air intake pipe (6), and the air intake pipe (6) is connected between the air intake connecting pipe (1) and the separation tee (2); a transition section (3-2) is provided at the connection between the collecting and dispersing ash hopper (3) and the separation tee (2), and the top end of the transition section (3-2) is connected to the air intake pipe (6). The distance between the lower wall of the transition section (3-2) and the vertical turning tube (4) is d, d satisfies 0≤d≤5a1, a1 is the diameter of the air intake connecting pipe (1), and the angle α between the transition section (3-2) and the vertical turning pipe (4) satisfies 0°≤α<90°; the lower part of the collecting and distributing ash hopper (3) is a dust discharge port (3-1), the dust discharge port (3-1) is wedge-shaped, and the dust discharge port (3-1) forms an angle γ, and the angle γ satisfies 0°≤γ≤75°; the diameter a2 of the sampling exhaust pipe (7) satisfies 0.3a1≤a2≤3a1, a1 is the diameter of the air intake connecting pipe (1); below the collecting and distributing ash hopper is an angle γ that forms a certain angle along the incoming direction of the flue gas, and the dust discharge port is in a "leeward" state, so that the collected ash is smoothly sent back to the original flue without being sucked by the flue gas for the second time to affect the ash discharge, so as to avoid the collected fly ash being sucked into the sample gas again, and ensure that the sample gas sucked by the sampling pipe is the clean flue gas after the removal.

2. The dust removal device for the SCR ammonia escape measuring instrument of a coal-fired power plant according to claim 1 is characterized in that: The vertical steering tube (4) is composed of a vertical section (4-1), a curved tube section (4-2) and a horizontal section (4-3) which are connected in sequence. The curvature radius r1 of the curved tube section (4-2) satisfies r1≥3a2, where a2 is the diameter of the vertical steering tube (4).

3. The dust removal device for the SCR ammonia escape measuring instrument of a coal-fired power plant according to claim 1 is characterized in that: The air inlet (1-1) of the air inlet connecting pipe (1) is a 90° elbow structure.

4. The dust removal device for the SCR ammonia escape measuring instrument of a coal-fired power plant according to claim 1 is characterized in that: The collecting and distributing ash hopper (3) is in the shape of a cone trumpet, the cone bottom angle θ satisfies 0°≤θ<90°, the cone bottom diameter D satisfies a1≤D≤10a1, and a1 is the diameter of the air intake connecting pipe (1).

5. A method for removing dust from SCR ammonia escape measuring instruments in coal-fired power plants, characterized in that: The SCR ammonia escape measuring instrument dust removal device for a coal-fired power plant as described in any one of claims 1 to 4 is used, and the method for dust removal of the SCR ammonia escape measuring instrument for a coal-fired power plant is as follows: the SCR ammonia escape measuring instrument dust removal device for a coal-fired power plant is incorporated into the flue gas sampling port of the flue gas measuring instrument to remove most of the dust in the flue gas, avoid dust accumulation on the dust removal filter of the suction contact measuring device to adsorb the escaped ammonia in the sample gas, thereby improving the representativeness of the sample gas, or for the suction external spectral test instrument, the problem of poor representativeness of the sample gas is also solved; the SCR ammonia escape measuring instrument dust removal device for a coal-fired power plant is located between the sampling probe and the sampling tube, and is arranged together with the sampling probe in the measuring The dust collecting and distributing hopper (3) is connected in series with the rear end of the steering sampling tube and is parallel thereto; the dust removal unit and the dust collecting and distributing hopper (3) are arranged in an integrated manner; the ash removed by the dust removal unit passes through the lower dust collecting and distributing hopper (3) and is returned to the flue (5); the dust removal unit comprises a special-shaped expansion and contraction port, a rear impact plate and at least two side plates, forming a special-shaped structural box body; the opening of the special-shaped structural box body is parallel to the flue gas inflow direction; the opening of the special-shaped structural box body forms an angle of 0-75° with the flue gas inflow direction, so that the dust discharge port (3-1) is in a leeward state, so that the ash collected by the dust removal unit is smoothly returned to the flue (5) without being affected by the secondary entrainment of the flue gas and affecting the ash discharge.

6. The method for removing dust from the SCR ammonia escape measuring instrument of a coal-fired power plant according to claim 5, characterized in that: The average flow velocity of the flue gas flowing through the air intake connecting pipe (1) and the sampling exhaust pipe (7) is not less than 3 m / s to prevent dust from being deposited in the pipes; the pipe diameter a1 of the air intake connecting pipe (1) and the pipe diameter a2 of the sampling exhaust pipe (7) are not less than 3 mm and not greater than 30 mm.

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