An ammonia escape monitoring system based on flue gas zoning

Abstract

The present application discloses an ammonia escape monitoring system based on flue duct zoning, which includes a number of sampling structures. The sampling structures penetrate into the flue duct and are located in different zones of the flue duct. The outer end of the sampling structure is connected to a sampling outer pipe in a communicating manner. The sampling outer pipe is connected to a mixing box in a communicating manner. The mixing box is connected to a negative pressure generator in a communicating manner. The air outlet end of the negative pressure generator passes through the outer wall of the flue duct and enters the inner cavity of the flue duct. The negative pressure generator is also connected to a first high-pressure air pipe. The mixing box is connected to an ammonia monitoring instrument and a nitrogen monitoring instrument in a communicating manner. The beneficial effects of this solution can be known from the description of the above solution. Sampling gases in different zones of the flue duct and mixing them before measurement, thus solving the problem of data representativeness caused by single-point extraction before. The sampling nozzle filters dust once, and the sampling disk filters dust again. At least two times of dust filtration solves the problem of great influence of soot in the detected gas, so that the measurement is more accurate.

Description

Technical Field

[0001] The present invention relates to the field of environmental protection technologies, and in particular to an ammonia slip monitoring system based on flue duct zoning. Background Art

[0002] Currently, large-scale power plants generally adopt SCR denitration devices to reduce the NO x emission concentration in flue gas. SCR utilizes the reduction characteristics of NH3 to NO x to reduce NO x to environmentally harmless N2 and H2O under the action of a catalyst. In the actual operation process, the control of the ammonia injection amount is particularly crucial. Increasing the ammonia injection amount is beneficial to reducing the NO x emission concentration, but the ammonia slip rate will increase accordingly, which will cause blockage and corrosion of the downstream air preheater due to the deposition of ammonium bisulfate. The accurate monitoring and evaluation of the ammonia slip rate at the denitration outlet are the key feedback signals for controlling the ammonia injection amount. In the prior art, generally, a NO x measurement device and an ammonia slip measurement device are installed at the denitration outlet simultaneously to realize the monitoring and evaluation of the ammonia slip rate.

[0003] However, the traditional on-line ammonia slip monitoring device uses a single-point laser pair-shooting measurement method, which has congenital defects such as inaccurate light alignment and excessive influence of soot; the NO x monitoring uses a single-point extraction and heating measurement, and the detected data has poor representativeness, unable to provide true and reliable data support for the control system, and there are hidden dangers such as untimely ammonia injection and exceeding environmental protection data standards; excessive ammonia injection blocking the air preheater. Summary of the Invention

[0004] The present invention aims at the deficiencies of the prior art and provides an ammonia slip monitoring system based on flue duct zoning. Gas samples are taken from different zones of the flue duct, mixed and then measured, thus solving the problem of the representativeness of the data generated by single-point extraction before; the sampling nozzle filters dust once, and the sampling disk filters dust again. At least two times of dust filtration solves the problem of the large influence of soot on the detected gas, so that the measurement is more accurate.

[0005] To achieve the above object, the present invention provides an ammonia slip monitoring system based on flue duct zoning, including a plurality of sampling structures, the sampling structures penetrate into the flue duct, and the sampling structures are located in different zones of the flue duct;

[0006] The outer end of the sampling structure is connected in communication with a sampling outer pipe, the sampling outer pipe is connected in communication with a mixing box, the mixing box is connected in communication with a negative pressure generator, and the air outlet end of the negative pressure generator passes through the flue duct outer wall and enters the flue duct inner cavity;

[0007] The negative pressure generator is further connected with a high-pressure air pipe I;

[0008] The mixing box is connected with an ammonia monitoring instrument and a nitrogen monitoring instrument.

[0009] Furthermore, the sampling structure includes a mounting cylinder which penetrates through the outer wall of the flue and has an outer diameter sealingly connected to the outer wall of the flue;

[0010] The outer end of the mounting cylinder is fixedly connected with a sampling disc, and the sampling disc is connected with a sampling rod which passes through the mounting cylinder and enters the inner cavity of the flue;

[0011] The sampling rod is provided with a sampling nozzle, and the opening of the sampling nozzle faces away from the direction of the flue gas flow;

[0012] The sampling disc is connected with a ball valve I, the ball valve I is connected with a union structure I, and the union structure I is connected with the sampling outer pipe.

[0013] Furthermore, the sampling disc includes an annular ring, the two sides of the annular ring are respectively connected with an outer side wall and an inner side wall, the inner side wall is connected with a threaded flange, and the threaded flange is threadedly connected with the sampling rod;

[0014] The outer side wall is provided with a cleaning port which is connected with a sampling housing;

[0015] A dust filtering member is arranged between the outer side wall and the inner side wall, and the dust filtering member is annular.

[0016] Furthermore, the union structure I includes a union seat, the upper end of the union seat is fixedly connected with the sampling outer pipe, the lower end of the union seat is threadedly connected with a connector, and a micro negative pressure instrument seat is arranged on the side surface of the union seat and connected with a micro negative pressure instrument;

[0017] The other end of the connector is threadedly connected with the ball valve I.

[0018] Furthermore, the sampling outer pipe includes a head section, a first transition section, a horizontal section, a second transition section and a tail end which are connected in sequence. The head section is arranged vertically, and the lower end of the head section is connected with the sampling structure;

[0019] The horizontal section is closely attached to the outer wall of the flue;

[0020] The tail end is connected with the mixing box.

[0021] Furthermore, the mixing box is installed on the outer wall of the flue, a through hole is opened on the outer wall of the flue, and the inner side of the mixing box is embedded into the inner cavity of the flue.

[0022] Furthermore, the first high-pressure air pipe is connected with a high-pressure air buffer tank, the high-pressure air buffer tank is connected with a second high-pressure air pipe, and the second high-pressure air pipe is connected with a total high-pressure air source.

[0023] Further, the first high-pressure gas pipe includes an intake section, a body section, and an outlet section. The intake section and the outlet section are located outside the flue, and the body section is located inside the flue.

[0024] The outlet section is connected to the high-pressure gas buffer tank and is also connected to the negative pressure generator.

[0025] The body section is provided with a number of S-shaped bends.

[0026] Further, a second union structure and a second ball valve are connected to the first high-pressure gas pipe near the negative pressure generator. The second union structure is connected to a positive air pressure gauge.

[0027] Further, a number of sampling structures are respectively provided on the left and right sides of the mixing tank.

[0028] The beneficial effects of this solution can be known from the description of the above solution. Compared with the prior art, it has the following beneficial effects:

[0029] (1) Sampling gases in different zones of the flue, mixing them, and then measuring, thus solving the problem of data representativeness caused by single-point extraction before.

[0030] (2) The sampling nozzle filters dust once, and the sampling disc filters dust again. At least two times of dust filtering solves the problem of great influence of soot in the detected gas, making the measurement more accurate.

[0031] (3) The horizontal section of the sampling outer pipe is closely attached to the outer wall of the flue, and the inner side wall of the mixing tank is embedded in the inner cavity of the flue, so that the detected gas is thermally insulated as much as possible to ensure the accuracy of the detection result.

[0032] (4) The body section of the first high-pressure gas pipe for heating is located in the inner cavity of the flue and is provided with S-shaped bends to heat the high-pressure gas as much as possible, so as to reduce the temperature difference between the detected gas and the high-pressure gas obtained by the negative pressure generator, and make the negative pressure generator heat evenly as much as possible.

[0033] (5) The sampling outer pipe is connected in series with the first union structure and the first ball valve, and the first union structure is connected to a micro negative pressure instrument, so as to control the air supply ratio of each sampling outer pipe to the mixing tank.

[0034] (6) The structure of the sampling disc makes it easier to clean the soot inside the dust filter and the sampling rod. It is very convenient to manually remove the ash or replace the dust filter. Moreover, it is also very convenient to directly apply high-pressure gas to the outer end of the sampling rod to blow the sampling nozzle in the reverse direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a schematic structural diagram of the present invention;

[0036] Figure 2 isFigure 1 Top view;

[0037] Figure 3 Schematic diagram of the installation structure of the sampling structure of the present invention;

[0038] Figure 4 is Figure 3 Enlarged view of part I of

[0039] Figure 5 is Figure 1 Enlarged view of part I of

[0040] Figure 6 Schematic diagram of the structure of the sampling outer tube of the present invention;

[0041] Figure 7 Schematic diagram of the structure of the first high-pressure gas pipe of the present invention.

[0042] In the figure, 1, installation cylinder; 2, outer wall of the flue; 3, sampling disc; 3-1, ring; 3-2, outer side wall; 3-3, inner side wall; 3-4, cleaning port; 4, threaded flange; 5, sampling rod; 5-1, sampling nozzle; 6, sampling cover; 7, dust filter; 8, ball valve I; 9, union structure I; 9-1, union seat; 9-2, connecting head; 9-3, micro-negative pressure gauge seat; 10, micro-negative pressure gauge 10; 11, sampling outer tube; 11-1, first section; 11-2, first transition section; 11-3, horizontal section; 11-4, second transition section; 11-5, ; 12, mixing box; 13, negative pressure generator; 14, ammonia monitoring instrument; 15, nitrogen monitoring instrument; 16, first high-pressure gas pipe; 16-1, intake section; 16-2, body section; 16-3, outlet section; 17, high-pressure gas buffer tank; 18, union structure II; 19, ball valve II; 20, positive pressure gauge. Detailed implementation manners

[0043] To clearly illustrate the technical features of this solution, the following elaborates on this solution through specific implementation manners.

[0044] As Figure 1 , 2 shown, this embodiment is an ammonia escape monitoring system based on flue partitioning, including a sampling structure. As Figure 3 , 4 shown, the sampling structure includes an installation cylinder 1, the installation cylinder 1 penetrates through the outer wall 2 of the flue and is hermetically connected to the outer wall 2 of the flue with an outer diameter; the outer end of the installation cylinder 1 is fixedly connected with a sampling disc 3, the sampling disc 3 includes a ring 3-1, both sides of the ring 3-1 are respectively connected with an outer side wall 3-2 and an inner side wall 3-3, the inner side wall 3-3 is connected with a threaded flange 4, the threaded flange 4 is threadedly connected to a sampling rod 5, the sampling rod 5 passes through the installation cylinder 1 and enters the flue inner cavity, and the sampling rod 5 is provided with a sampling nozzle 5-1, and the opening of the sampling nozzle 5-1 faces away from the direction of the flue gas flow.

[0045] The outer wall 3-2 is provided with a cleaning port 3-4, and the cleaning port 3-4 is connected with a sampling housing 6; a dust filtering member 7 is arranged between the outer wall 3-2 and the inner wall 3-3, and the dust filtering member 7 is annular.

[0046] A support structure is arranged in the flue for supporting the sampling rod 5, and the sampling rod 5 is horizontally installed.

[0047] As Figure 5 shown, a ball valve I 8 is connected and communicated above the sampling disc 3, the ball valve I 8 is connected and communicated with a union structure I 9, the union structure I 9 includes a union seat 9-1, the lower end of the union seat 9-1 is threadedly connected with a connector 9-2, and the other end of the connector 9-2 is threadedly connected with the ball valve I 8; a micro negative pressure instrument seat 9-3 is arranged on the side of the union seat 9-1 and connected with a micro negative pressure instrument 10; the upper end of the union seat 9-1 is fixedly connected with a sampling outer tube 11.

[0048] As Figure 6 shown, the sampling outer tube 11 includes a first section 11-1, a first transition section 11-2, a horizontal section 11-3, a second transition section 11-4 and a tail end 11-5 which are connected in sequence. The first section 11-1 is erected, and the lower end of the first section 11-1 is connected and communicated with a sampling structure; the horizontal section 11-3 is closely attached to the outer wall 2 of the flue; the tail end 11-5 is connected and communicated with a mixing box 12.

[0049] As Figure 2 shown, the mixing box 12 is installed on the outer wall 2 of the flue, a through hole is opened on the outer wall 2 of the flue, and the inner side of the mixing box 12 is embedded into the flue inner cavity. A space of 200 mm is reserved between the mixing box 12 and the reinforcing ribs around it to facilitate welding of the mixing box 12.

[0050] Four sets of sampling structures are connected and communicated on both the left and right sides of the mixing box 12, and the distances between the four sampling rods 5 on both sides of the mixing box 12 are the same, that is, the sampling point distances are equal. There are no reinforcing ribs within 200 mm around the edge of the installation cylinder 1, and the sampling housing 6 is not interfered by the reinforcing ribs during installation.

[0051] The sampling outer tube 11 is a φ16×2 type tube made of 304# steel material. After bending the sampling outer tube 11 into a corresponding shape with a pipe bender according to the corresponding relationship between the flue gas inlet of the mixing box 12 and the flue gas outlet of the sampling rod 5, one end of the sampling outer tube 11 is spot welded with the union structure I 9 and then taken down together, and then the sampling outer tube 11 is fully welded with the union seat 9-1. The copper gaskets of the union structure I 9 and the micro negative pressure instrument 10 are annealed and then installed in the corresponding positions, and the connector 9-2 is tightened.

[0052] Argon arc welding must be used for pipeline welding; when forming and sampling the outer pipe 11, the principle that the distal sampling outer pipe 11 is on top should be followed to avoid pipeline crossing and affecting the appearance; when the pipeline is in place, the outlet of the sampling disc 3 should be coaxial with the union structure Yi 9 to ensure no leakage occurs when the connector 9-2 is tightened; the connection between the sampling outer pipe 11 and the mixing box 12 should be fully welded.

[0053] The mixing box 12 is connected and communicated with a negative pressure generator 13, and the air outlet end of the negative pressure generator 13 passes through the flue outer wall 2 and enters the flue inner cavity; the mixing box 12 is connected and communicated with an ammonia monitoring instrument 14 and a nitrogen monitoring instrument 15.

[0054] The negative pressure generator 13 is also connected with a first high-pressure air pipe 16, the first high-pressure air pipe 16 is connected and communicated with a high-pressure air buffer tank 17, the high-pressure air buffer tank 17 is connected and communicated with a second high-pressure air pipe, and the second high-pressure air pipe is connected and communicated with the total high-pressure air source. The first high-pressure air pipe 16 is a φ20×2 type pipe.

[0055] As Figure 7 shown, the first high-pressure air pipe 16 includes an intake section 16-1, a body section 16-2 and an outlet section 16-3. The intake section 16-1 and the outlet section 16-3 are located outside the flue, and the body section 16-2 is located inside the flue; the outlet section 16-3 is connected and communicated with the high-pressure air buffer tank 17, and the outlet section 16-3 is connected and communicated with the negative pressure generator 13; several S-shaped bends are provided on the body section 16-2.

[0056] As Figure 2 shown, a second union structure 18 and a second ball valve 19 are connected and communicated at the part of the first high-pressure air pipe 16 close to the negative pressure generator 13, and a positive air pressure gauge 20 is connected to the second union structure 18.

[0057] During operation, the opening degree of the second ball valve 19 is controlled by the data of the positive air pressure gauge 20, and the high-pressure air enters the negative pressure generator 13 after increasing the temperature through the body section 16-2. Under the suction of the negative pressure generator 13, the flue gas in the flue enters the sampling nozzle 5-1, reaches the sampling disc 3 through the sampling rod 5, and enters the sampling outer pipe 11 after another dust filtration.

[0058] The readings of each micro negative pressure gauge 10 are controlled by the first ball valve 8 to adjust the gas flow rate of each sampling outer pipe 11. The flue gas enters the mixing box 12 through the sampling outer pipe 11. The ammonia monitoring instrument 14 and the nitrogen monitoring instrument 15 above the mixing box 12 conduct detection.

[0059] Then, the mixed flue gas is sucked by the negative pressure generator 13 and then sent back into the flue.

[0060] When it is necessary to clean the soot at both ends of the sampling rod 5, just remove the sampling cover 6, and then the soot attached to the dust filter member 7 can be cleaned, or the dust filter chamber can be replaced. Use a long dry brush to clean the inside of the sampling rod 5. Connect high-pressure air at the end of the sampling rod 5 to blow off the soot attached to the outside of the sampling nozzle 5-1.

[0061] The technical features not described in the present invention can be realized by or adopted from the prior art, and will not be elaborated here. Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by those of ordinary skill in the art within the scope of the essence of the present invention shall also fall within the protection scope of the present invention.

Claims

1. An ammonia escape monitoring system based on flue gas zoning, characterized in that, It includes several sampling structures which penetrate into the flue duct and are located in different zones of the flue duct. The outer end of the sampling structure is connected in a communicating manner with a sampling outer pipe, the sampling outer pipe is connected in a communicating manner with a mixing box, the mixing box is connected in a communicating manner with a negative pressure generator, and the air outlet end of the negative pressure generator penetrates through the outer wall of the flue duct and enters the inner cavity of the flue duct. The negative pressure generator is also connected with a high-pressure air pipe I. The mixing box is connected in a communicating manner with an ammonia monitoring instrument and a nitrogen monitoring instrument. The sampling structure includes an installation cylinder which penetrates through the outer wall of the flue duct and whose outer diameter is sealingly connected with the outer wall of the flue duct. The outer end of the installation cylinder is fixedly connected with a sampling disc, the sampling disc is connected in a communicating manner with a sampling rod, and the sampling rod penetrates through the installation cylinder and enters the inner cavity of the flue duct. The sampling rod is provided with a sampling nozzle whose opening faces away from the incoming direction of the flue gas flow. The sampling disc is connected in a communicating manner with a ball valve I, the ball valve I is connected in a communicating manner with a union structure I, and the union structure I is connected in a communicating manner with the sampling outer pipe. The union structure I includes a union seat, the upper end of the union seat is fixedly connected with the sampling outer pipe, the lower end of the union seat is threadedly connected with a connector, and a micro negative pressure instrument seat is arranged on the side of the union seat and connected with a micro negative pressure instrument. The other end of the connector is threadedly connected with the ball valve I. The sampling disc includes a ring, the two sides of the ring are respectively connected with an outer side wall and an inner side wall, the inner side wall is connected with a threaded flange which is threadedly connected with the sampling rod. The outer side wall is provided with a cleaning port which is connected with a sampling housing. A filter dust member is arranged between the outer side wall and the inner side wall, and the filter dust member is annular.

2. The ammonia escape monitoring system based on flue duct zoning according to claim 1, wherein The sampling outer pipe includes a head section, a first transition section, a horizontal section, a second transition section and a tail end which are connected in sequence, the head section is erected, and the lower end of the head section is connected in a communicating manner with the sampling structure. The horizontal section is closely attached to the outer wall of the flue duct. The tail end is connected in a communicating manner with the mixing box.

3. The ammonia slip monitoring system based on flue gas zoning according to claim 1, characterized in that, The mixing box is installed on the outer wall of the flue duct, a through hole is opened on the outer wall of the flue duct, and the inner side of the mixing box is embedded into the inner cavity of the flue duct.

4. The ammonia escape monitoring system based on flue duct zoning according to claim 1, characterized in that, The high-pressure air pipe I is connected in a communicating manner with a high-pressure air buffer box, the high-pressure air buffer box is connected in a communicating manner with a high-pressure air pipe II, and the high-pressure air pipe II is connected in a communicating manner with a total high-pressure air source.

5. The ammonia escape monitoring system based on flue duct zoning according to claim 1, characterized in that, The high-pressure air pipe I includes an air inlet section, a body section and an air outlet section, the air inlet section and the air outlet section are located outside the flue duct, and the body section is located inside the flue duct. The air outlet section is connected in a communicating manner with the high-pressure air buffer box and is also connected in a communicating manner with the negative pressure generator. The body section is provided with several S-shaped bends.

6. The ammonia slip monitoring system based on flue duct zoning according to claim 1, wherein A union structure II and a ball valve II are connected in a communicating manner at a position of the high-pressure air pipe I close to the negative pressure generator, and the union structure II is connected with a positive air pressure gauge.

7. The ammonia escape monitoring system based on flue duct zoning according to claim 1, characterized in that, Several sampling structures are respectively arranged on the left and right sides of the mixing box.

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