Multi-point equal-flow sampling device of flue gas denitration system

Abstract

The invention discloses a multi-point equal-flow sampling device of a flue gas denitration system, which comprises a denitration flue, a plurality of sampling pipes, a collecting pipe, a gas analysis chamber, a sampling pump and an exhaust pipe, and the flue gas in the denitration flue flows from top to bottom; a plurality of sampling pipes horizontally penetrate into the denitration flue, are uniformly arranged at intervals and are fixed in the denitration flue through guide brackets, and a plurality of gas inlet pipes are arranged at the bottoms of the sampling pipes at intervals; the front end of the sampling pipe is sealed, the tail end of the sampling pipe extends out of the denitration flue to be connected with the collecting pipe, the collecting pipe is connected with the gas analysis chamber, the gas analysis chamber is connected with an inlet of the sampling pump, an outlet of the sampling pump is connected with the exhaust pipe, the exhaust pipe is connected with the denitration flue, and the connecting point of the exhaust pipe and the denitration flue is located below the sampling pipe. The sampling pipe and the collecting pipe are both conical round pipes, the flow velocity in the pipes is kept by changing the diameters of the sampling pipe and the collecting pipe, and the dynamic pressure is kept constant, so that the static pressure change is eliminated, and multi-point equal-flow uniform sampling is realized.

Description

Technical Field

[0001] This application relates to the field of energy conservation and environmental protection, specifically to a multi-point equal flow sampling device for a flue gas denitrification system. Background Technology

[0002] Nitrogen oxides (NOx) emitted by coal-fired power units are among the major air pollutants, directly contributing to acid rain and causing soil and water acidification, severely damaging the ecological environment. Selective catalytic reduction (SCR) is the most widely used NOx removal method in coal-fired power plants. SCR uses NH3 as a reducing agent, reducing NOx in flue gas to N2 under the action of a catalyst.

[0003] With the increasing intensity of deep peak shaving by coal-fired power units and the increasingly stringent environmental protection standards, the requirements for precise control of flue gas denitrification systems are also gradually increasing. The accuracy of NOx measurement in the denitrification system is crucial for the precise control of flue gas denitrification.

[0004] The denitrification system suffers from several drawbacks, including a large cross-sectional area of ​​the SCR reactor flue, fluctuations and uneven distribution of nitrogen oxide (NOx) concentrations, resulting in poor data representativeness from single-point extraction sampling and single-point in-situ measurements. Multi-point in-situ measurements are costly, complex, and difficult to maintain. Furthermore, traditional multi-point mixed sampling methods for NOx measurement are susceptible to the effects of pipe resistance and blockages, making it difficult to achieve uniform sampling and leading to significant differences in flue gas extraction rates at different locations, resulting in large deviations between measured and actual NOx values. This patent proposes a multi-point isoflow sampling device for flue gas denitrification systems to achieve uniform sampling of the denitrification flue cross-section, ensuring the uniformity of measurement data. Summary of the Invention

[0005] To address the aforementioned technical problems in the existing technology, the purpose of this application is to provide a multi-point equal flow sampling device for a flue gas denitrification system. This application aims to achieve uniformity of flue gas flow across the denitrification flue section by performing multi-point equal flow sampling.

[0006] The technical solution adopted in this application is as follows:

[0007] A multi-point isoflow sampling device for a flue gas denitrification system includes a denitrification flue, several sampling tubes, a manifold, a gas analysis chamber, a sampling pump, and an exhaust pipe. The flue gas flow direction in the denitrification flue is from top to bottom.

[0008] The sampling tubes are horizontally inserted into the denitrification flue. The sampling tubes are evenly spaced apart from each other and are all fixed inside the denitrification flue by guide brackets. Multiple air inlet pipes are evenly spaced at the bottom of each sampling tube. The front end of the sampling tube is sealed and the end extends to the outside of the denitrification flue and connects to the manifold. The manifold is connected to the gas analysis chamber. The gas analysis chamber is connected to the inlet of the sampling pump. The outlet of the sampling pump is connected to the exhaust pipe. The exhaust pipe is then connected to the denitrification flue. The connection point between the exhaust pipe and the denitrification flue is located below the sampling tube.

[0009] Furthermore, the sampling tube is a conical round tube, with both the front and rear ends of the sampling tube connected to the sidewall of the denitrification flue; the diameter of the sampling tube gradually increases along the direction extending from the front end to the rear end.

[0010] Furthermore, n air inlet pipes are installed at the bottom of the sampling tube, where n is an integer ≥ 3. The first air inlet pipe is located near the front end of the sampling tube, and the nth air inlet pipe is located near the end of the sampling tube. The diameter of the sampling tube at the center of the nth air inlet pipe is [missing information - likely a percentage] of the air inlet pipe diameter. times.

[0011] Furthermore, the intake pipe is a round or square pipe, and the opening of the intake pipe is vertically downward.

[0012] Furthermore, several semi-circular steel pipes are installed inside the denitrification flue. The number of semi-circular steel pipes is the same as the number of sampling tubes. A semi-circular steel pipe is installed directly above the windward side of each sampling tube, with the arc-shaped convex surface of the semi-circular steel pipe facing upward.

[0013] Furthermore, the diameter D of the semicircular steel pipe is the same as the diameter of the end of the sampling tube, and the distance between the center line of the semicircular steel pipe and the center line of the sampling tube is 1.5D to 2.5D.

[0014] Furthermore, the manifold is a tapered circular tube, with all sampling tubes located on the same horizontal plane and their ends extending to the outside of the denitrification flue and connecting to the side wall of the manifold;

[0015] Along the direction from the front end of the manifold to its end, the diameter of the manifold gradually increases; at the end of the manifold, 2 to 5 semi-circular mixing baffles are staggered on both sides of the internal centerline, which promote the uniform mixing of the sampled gas under the turbulence effect of the mixing baffles.

[0016] Furthermore, k sampling tubes are connected to the side of the manifold, where k is an integer ≥ 3. The first sampling tube is located near the front end of the manifold, and the kth sampling tube is located near the end of the manifold. The diameter of the manifold at the interface of the kth sampling tube is the same as the diameter at the interface of the first sampling tube. times;

[0017] The mixing baffle is inclined along the direction of flue gas flow inside the manifold, and the angle between the mixing baffle and the inner wall of the manifold is 60-75°.

[0018] Furthermore, a compressed air backflush port with a first isolation valve is provided at the top of the end of the manifold to prevent dust accumulation and blockage in the sampling tube and the manifold; the end of the manifold is connected to the gas analysis chamber through an arc-shaped bend and a manifold isolation valve, which is used for isolation during compressed air backflush.

[0019] The manifold is equipped with a drain isolation valve at its bottom end.

[0020] Furthermore, the analysis chamber is equipped with an in-situ flue gas measurement and analysis instrument or a CEMS sampling port for flue gas composition analysis; the sampling pump is a volumetric vacuum pump.

[0021] Compared with the prior art, the beneficial effects achieved by this application are:

[0022] This application inserts several sampling tubes horizontally into the denitrification flue. All sampling tubes are located on the same horizontal plane and perpendicular to the flue gas flow direction. The representativeness of pollutant measurement data is improved by arranging the sampling points. The sampling tubes and manifolds are made into conical circular tubes. By changing the diameter of the sampling tubes and manifolds, the flow velocity inside the tubes is maintained and the dynamic pressure is kept constant, thereby eliminating static pressure changes and realizing multi-point uniform sampling with equal flow rates. After sampling, the gas passes through a mixing baffle to achieve uniform mixing of the flue gas and improve the accuracy of flue gas sampling measurement. Attached Figure Description

[0023] Figure 1 This is a front view of a multi-point equal flow sampling device for a flue gas denitrification system according to this application;

[0024] Figure 2 This is a side sectional view of a multi-point equal flow sampling device for a flue gas denitrification system according to this application;

[0025] Figure 3 This is a top sectional view of a multi-point equal flow sampling device for a flue gas denitrification system according to this application;

[0026] Explanation of reference numerals in the attached drawings: 1-Sampling tube, 2-Manifold, 3-Gas analysis chamber, 4-Sampling pump, 5-Exhaust pipe, 6-Sampling inlet pipe, 7-Semi-circular steel pipe, 8-Compressed air backflush port, 9-First isolation valve, 10-Manifold isolation valve, 11-Mixed flow baffle, 12-Drain pipe, 13-Drain isolation valve. Detailed Implementation

[0027] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0028] Example: Comparison Figures 1-3

[0029] A multi-point equal flow sampling device for a flue gas denitrification system includes a denitrification flue, several sampling pipes 1, a manifold 2, a gas analysis chamber 3, a sampling pump 4, and an exhaust pipe 5. The flue gas flow direction in the denitrification flue is from top to bottom.

[0030] Several sampling tubes 1 are horizontally inserted into the denitrification flue. There can be nine sampling tubes 1. The sampling tubes 1 are evenly spaced and fixed inside the denitrification flue by guide brackets. Each sampling tube 1 has four air inlet pipes 6 evenly spaced from front to back at its bottom. All sampling tubes 1 are located on the same horizontal plane. The front end of the sampling tube 1 is sealed, and its rear end extends outside the denitrification flue and connects to the side wall of the manifold 2. The manifold 2 connects to the gas analysis chamber 3, which in turn connects to the inlet of the sampling pump 4. The outlet of the sampling pump 4 connects to the exhaust pipe 5, which in turn connects to the denitrification flue. The connection point between the exhaust pipe 5 and the denitrification flue is located below the sampling tube 1.

[0031] Sampling tube 1 is a conical cylindrical tube, with both its front and rear ends connected to the sidewall of the denitrification flue. The diameter of sampling tube 1 gradually increases from its front end to its rear end. n (n=4) air inlets 6 are installed at the bottom of sampling tube 1. The first air inlet 6 is located near the front end of sampling tube 1, and the nth air inlet 6 is located near the rear end. The diameter of sampling tube 1 at the center of the fourth air inlet 6 is twice the diameter of the air inlet 6. The diameter of the front end of sampling tube 1 is 1.1 times the diameter of the air inlet 6.

[0032] The air inlet pipe 6 is a round or square pipe. The opening direction of the air inlet pipe 6 is vertically downward and follows the flow direction of the flue gas in the denitrification flue. Its advantage is that it can effectively reduce the amount of dust entering the sampling pipe.

[0033] Multiple semi-circular steel pipes 7 are also installed inside the denitrification flue. The number of semi-circular steel pipes 7 is the same as the number of sampling pipes 1. A semi-circular steel pipe 7 is installed directly above the windward side of each sampling pipe 1. The arc-shaped convex surface of the semi-circular steel pipe 7 is set upward, that is, the arc-shaped convex surface of the semi-circular steel pipe 7 is set facing the flue gas inside the denitrification flue.

[0034] The flue gas in the denitrification flue contains a high concentration of particulate matter, which can scour the tube bundle under high flue gas flow rates. If the sampling tube 1 is scourged for a long time, it can easily lead to damage and leakage. In this invention, a semi-circular steel pipe 7 is installed directly above the windward side of the sampling tube 1. The flue gas flowing from top to bottom scours the semi-circular steel pipe 7, thereby extending the service life of the sampling tube 1.

[0035] The diameter D of the semicircular steel pipe 7 is the same as the diameter of the end of the sampling tube 1, and the distance between the center line of the semicircular steel pipe and the center line of the sampling tube is 1.5D to 2.5D.

[0036] The manifold 2 is a conical circular tube, and all sampling tubes 1 are located on the same horizontal plane and their ends extend to the outside of the denitrification flue and connect to the side wall of the manifold 2. Along the direction from the front end of the manifold 2 to its end, the diameter of the manifold 2 gradually increases. Four semi-circular mixing baffles 11 are staggered on both sides of the inner centerline at the end of the manifold 2. Under the turbulence effect of the mixing baffles 11, the sampling gas is uniformly mixed.

[0037] Nine sampling tubes 1 are connected to the side of the manifold 2. The first sampling tube 1 is close to the front end of the manifold 2, and the ninth sampling tube 1 is close to the end of the manifold 2. The diameter of the manifold 2 at the interface of the ninth sampling tube is three times the diameter at the interface of the first sampling tube.

[0038] The mixing baffle 11 is inclined along the flue gas flow direction inside the manifold 2, and the angle between the mixing baffle 11 and the inner wall of the manifold 2 is 60-75°.

[0039] The top of the end of the manifold 2 is equipped with a compressed air backflush port 8 with a first isolation valve 9 to prevent dust accumulation and blockage in the sampling tube 1 and the manifold 2. The end of the manifold 2 is connected to the gas analysis chamber 3 through an arc-shaped bend and a manifold isolation valve 10, which serves as an isolation valve during compressed air backflush. The bottom of the end of the manifold 2 is equipped with a manifold outlet 12 with a drain isolation valve 13.

[0040] The analysis chamber is equipped with an in-situ flue gas measurement and analysis instrument or a CEMS sampling port for flue gas composition analysis; the sampling pump is a positive displacement vacuum pump.

[0041] The contents described in this specification are merely an enumeration of the implementation forms of the inventive concept, and the scope of protection of this invention should not be regarded as limited to the specific forms described in the embodiments.

Claims

1. A multi-point isoflow sampling device for a flue gas denitrification system, characterized in that, It includes a denitrification flue, several sampling tubes (1), a manifold (2), a gas analysis chamber (3), a sampling pump (4), and an exhaust pipe (5). The flue gas flow direction in the denitrification flue is from top to bottom. The sampling tubes (1) are horizontally inserted into the denitrification flue. The sampling tubes (1) are evenly spaced apart from each other and are all fixed inside the denitrification flue by guide brackets. Multiple air inlet pipes (6) are evenly spaced at the bottom of each sampling tube (1). The front end of the sampling tube (1) is sealed and the end extends to the outside of the denitrification flue and connects to the manifold (2). The manifold (2) is connected to the gas analysis chamber (3). The gas analysis chamber (3) is connected to the inlet of the sampling pump (4). The outlet of the sampling pump (4) is connected to the exhaust pipe (5). The exhaust pipe (5) is then connected to the denitrification flue. The connection point between the exhaust pipe (5) and the denitrification flue is located below the sampling tube (1).

2. The multi-point equal flow sampling device for a flue gas denitrification system as described in claim 1, characterized in that, The sampling tube (1) is a tapered round tube, and both the front end and the end end of the sampling tube (1) are connected to the side wall of the denitrification flue. Along the direction from the front end of the sampling tube (1) to its end end, the diameter of the sampling tube (1) gradually increases.

3. The multi-point equal flow sampling device for a flue gas denitrification system as described in claim 2, characterized in that, The sampling tube (1) has n air inlet pipes (6) at its bottom, where n is an integer greater than or equal to 3. The first air inlet pipe (6) is located near the front end of the sampling tube (1), and the nth air inlet pipe (6) is located near the end of the sampling tube (1). The diameter of the sampling tube (1) at the center of the nth air inlet pipe (6) is a fraction of the diameter of the air inlet pipe (6). times.

4. The multi-point equal flow sampling device for a flue gas denitrification system as described in claim 1, characterized in that, The intake pipe (6) is a round or square pipe, and the opening of the intake pipe (6) is vertically downward.

5. The multi-point equal flow sampling device for a flue gas denitrification system as described in claim 1, characterized in that, Several semi-circular steel pipes (7) are also installed inside the denitrification flue. The number of semi-circular steel pipes (7) is the same as the number of sampling pipes (1). A semi-circular steel pipe (7) is installed directly above the windward side of each sampling pipe (1), with the arc-shaped convex surface of the semi-circular steel pipe (7) facing upward.

6. The multi-point equal flow sampling device for a flue gas denitrification system as described in claim 5, characterized in that, The diameter D of the semicircular steel pipe (7) is the same as the diameter of the end of the sampling tube (1), and the distance between the center line of the semicircular steel pipe and the center line of the sampling tube is 1.5D to 2.5D.

7. The multi-point equal flow sampling device for a flue gas denitrification system as described in claim 1, characterized in that, The manifold (2) is a conical tube, and all sampling tubes (1) are located on the same horizontal plane and their ends extend to the outside of the denitrification flue and are connected to the side wall of the manifold (2); Along the direction from the front end of the manifold (2) to its end, the diameter of the manifold (2) gradually increases; 2 to 5 semi-circular mixing baffles (11) are staggered on both sides of the inner centerline at the end of the manifold (2), and the sampling gas is uniformly mixed under the turbulence effect of the mixing baffles (11).

8. The multi-point equal flow sampling device for a flue gas denitrification system as described in claim 7, characterized in that, The manifold (2) is connected to k sampling tubes (1) on its side, where k is an integer greater than or equal to 3. The first sampling tube (1) is located near the front end of the manifold (2), and the kth sampling tube (1) is located near the end of the manifold (2). The diameter of the manifold (2) at the interface of the kth sampling tube is equal to the diameter at the interface of the first sampling tube. times; The mixing baffle (11) is inclined along the flue gas flow direction inside the manifold (2), and the angle between the mixing baffle (11) and the inner wall of the manifold (2) is 60-75°.

9. The multi-point equal flow sampling device for a flue gas denitrification system as described in claim 1, characterized in that, A compressed air backflush port (8) with a first isolation valve (9) is provided at the top of the end of the manifold (2) to prevent dust accumulation and blockage in the sampling tube (1) and the manifold (2); the end of the manifold (2) is connected to the gas analysis chamber (3) through an arc-shaped bend and a manifold isolation valve (10), and the manifold isolation valve (10) is used for isolation during compressed air backflush; The bottom end of the manifold (2) is provided with a manifold outlet (12) equipped with a sewage isolation valve (13).

10. The multi-point equal flow sampling device for a flue gas denitrification system as described in claim 1, characterized in that, The analysis chamber is equipped with in-situ flue gas measurement and analysis instruments or CEMS sampling ports for flue gas composition analysis; The sampling pump is a positive displacement vacuum pump.

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