Anti-blocking NOx concentration zone sampling and measurement device and SCR denitrification system

Abstract

The utility model relates to the technical field of tail gas denitration, and discloses a blocking-proof NOx concentration partition sampling and measuring device and an SCR denitration system. The blocking-proof NOx concentration partition sampling and measuring device includes a plurality of sampling probes for extracting flue gas to be measured from different positions in the flue gas of the denitration outlet; a plurality of sampling branches connected to the corresponding sampling probes, and a sampling switching valve is installed on the sampling branch; a NOx analyzer for measuring the concentration of NOx in the flue gas flowing out of the sampling branch; a backflush assembly arranged downstream of the sampling branch, and the backflush assembly is used to blow gas to the sampling branch at a pressure higher than the flue gas pressure in the sampling branch; and an electrostatic eliminator arranged downstream of the sampling branch, and the electrostatic eliminator is arranged to be able to ionize the gas into positive ions and negative ions. Through the above technical scheme, the backflush assembly is used to blow high-pressure gas, positive ions and negative ions to the sampling branch, thereby preventing dust from blocking the sampling branch.

Description

Technical Field

[0001] The utility model relates to the technical field of tail gas denitration, and in particular to an anti-blocking NOx concentration zoning sampling and measuring device, and on this basis, also relates to an SCR denitration system. Background Art

[0002] At present, coal-fired power plants generally use SCR denitrification technology to reduce the concentration of NOx emissions. SCR denitrification technology uses the reduction characteristics of NH3 to NOx, and reduces NOx to environmentally friendly N2 and H2O under the action of a catalyst. In the actual operation process, the control of the amount of ammonia injection is particularly critical. Increasing the amount of ammonia injection is conducive to reducing the NOx emission concentration, but ammonia escape will increase, which will cause the downstream air preheater to be blocked and corroded due to the deposition of ammonium bisulfate. In terms of ammonia injection control, in addition to reasonably controlling the total amount of ammonia injection, attention should also be paid to the uniformity of ammonia injection (specifically, the "uniformity of the ammonia nitrogen molar ratio at the denitrification inlet", which is manifested as the "uniformity of the NOx concentration distribution at the denitrification outlet") to ensure relative uniformity to ensure that the NOx emission concentration meets the standard within the allowable ammonia escape range.

[0003] In recent years, the denitrification zoned ammonia injection control technology has been widely used. The core process of this technology at least includes the denitrification outlet NOx concentration zoned measurement technology. However, due to the high dust layout of the SCR denitrification reactor, the dust concentration in the flue gas is relatively high, and the zoned sampling pipeline is prone to blockage.

[0004] In order to solve the problem of easy blockage of partition sampling pipelines, the industry generally adopts a gas source with a relatively higher flue gas pressure for backblowing, such as compressed air backblowing or boiler primary air backblowing. However, due to the strong adhesion of fly ash, simple backblowing cannot completely solve the problem of easy blockage of partition sampling pipelines. In actual applications, the problem of blockage of partition sampling pipelines is still prone to occur. Utility Model Content

[0005] The utility model aims to overcome the problem of easy clogging of the partition sampling pipeline in the prior art, and provides a blockage-proof NOx concentration partition sampling and measuring device and an SCR denitrification system. The blockage-proof NOx concentration partition sampling and measuring device has the advantage of not being easy to be clogged.

[0006] The first aspect of the utility model provides an anti-blocking NOx concentration zoning sampling and measuring device, comprising: a plurality of sampling probes, the plurality of sampling probes are used to extract the flue gas to be measured from different positions in the denitrification outlet flue; a plurality of sampling branches, the plurality of sampling branches are connected to the corresponding sampling probes, and a sampling switching valve is installed on the sampling branch; a NOx analyzer, the NOx analyzer is used to measure the concentration of NOx in the flue gas flowing out of the sampling branch; a backflush component, the backflush component is arranged downstream of the sampling branch, and is used to blow gas into the sampling branch at a pressure higher than the flue gas pressure in the sampling branch; and a static eliminator, the static eliminator is arranged downstream of the sampling branch, and the static eliminator is configured to be able to ionize the gas into positive ions and negative ions.

[0007] Through the above technical solution, multiple sampling probes are connected to the sampling branch pipes, and the sampling switching valves on the sampling branch pipes are controlled to open and close, so as to control the corresponding sampling probes to extract the flue gas to be measured from the denitrification outlet flue. The flue gas flows through the sampling probes and the sampling branch pipes and enters the NOx analyzer, and the NOx concentration in the flue gas is obtained by the NOx analyzer. The opening or closing state of the sampling switching valves on different sampling branches is adjusted so that the sampling probes at different positions in the denitrification outlet flue can extract the flue gas, so that the NOx concentration of the flue gas at different positions in the denitrification outlet flue can be measured. In addition, the backflush assembly is used to blow gas higher than the flue gas pressure in the sampling branch pipe to reduce the risk of clogging the sampling branch pipe due to excessive dust content in the sampling branch pipe. Furthermore, an electrostatic eliminator is used to ionize the gas blown by the backflush component into positive ions and negative ions, which are blown toward the sampling branch pipe by the backflush component and combine with the statically charged dust in the sampling branch pipe, thereby eliminating the static electricity of the dust and preventing the dust from clogging the sampling branch pipe due to electrostatic adsorption.

[0008] Optionally, the anti-blocking NOx concentration zoning sampling and measuring device provided by the utility model also includes a sampling main pipe, the outlets of multiple sampling branch pipes merge and are connected to the inlet of the sampling main pipe, the NOx analyzer is installed on the sampling main pipe, and the backflush assembly and the static eliminator are connected to the sampling main pipe.

[0009] Optionally, the anti-blocking NOx concentration zone sampling and measuring device provided by the utility model also includes a negative pressure vacuum pump installed on the sampling main pipe and a sampling main valve connected to the outlet of the sampling main pipe, and the negative pressure vacuum pump is arranged downstream of the NOx analyzer.

[0010] Optionally, the minimum distance between the sampling branch tube and the sampling main tube and the flue wall whose temperature is higher than that of the sampling branch tube and the sampling main tube does not exceed 20 cm, so as to increase the temperature of the sampling branch tube and the sampling main tube.

[0011] Optionally, the anti-blocking NOx concentration zone sampling and measuring device provided by the utility model also includes a backblowing pipe whose two ends are respectively connected to the backblowing gas source and the sampling main pipe at a position between the NOx analyzer and the negative pressure exhauster, and the backblowing assembly and the static eliminator are installed on the backblowing pipe.

[0012] Optionally, the back-blowing assembly includes a back-blowing gas source driving mechanism and a back-blowing valve.

[0013] Optionally, the back-blowing gas source driving mechanism includes a pulse generator.

[0014] Optionally, the sampling probe extends perpendicularly to the flue gas flow direction in the denitrification outlet flue.

[0015] Optionally, the inlet of the sampling probe extends into the denitrification outlet flue and extends to the central axis of the denitrification outlet flue.

[0016] The second aspect of the utility model provides an SCR denitration system, comprising the above-mentioned anti-blocking NOx concentration zoning sampling and measuring device. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the anti-blocking NOx concentration partition sampling and measuring device provided by the utility model.

[0018] Description of Reference Numerals

[0019] 1-denitrification outlet flue; 2-air preheater inlet flue; 3-sampling probe; 4-sampling branch pipe; 5-sampling switching valve; 6-sampling main pipe; 7-NOx analyzer; 8-sampling main valve; 9-negative pressure vacuum pump; 10-backblowing gas source; 11-backblowing pipe; 12-backblowing valve; 13-pulse generator; 14-static eliminator. DETAILED DESCRIPTION

[0020] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0021] In the present utility model, unless otherwise specified, the directions or positional relationships indicated by terms such as "up, down, left, right, inside, outside, top, bottom" are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present utility model.

[0022] In addition, in the description of the present invention, the term "plurality" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0023] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0024] The following describes the anti-blocking NOx concentration partition sampling and measuring device and the SCR denitrification system disclosed in the utility model with reference to the accompanying drawings.

[0025] The first aspect of the utility model provides an anti-blocking NOx concentration partition sampling and measuring device, referring to Figure 1 As shown, the anti-blocking NOx concentration zoning sampling and measuring device includes: a plurality of sampling probes 3, a plurality of sampling branches 4, a NOx analyzer 7, a backflush assembly and a static eliminator 14, wherein the inlets of the plurality of sampling probes 3 are arranged at different positions in the denitrification outlet flue 1, so that the flue gas to be measured can be extracted from different positions in the denitrification outlet flue 1, the inlets of the plurality of sampling branches 4 are connected with the outlets of the corresponding sampling probes 3, and the outlets of the sampling branches 4 can be connected with the NOx analyzer 7, and the flue gas to be measured extracted by the sampling probes 3 enters the NOx analyzer 7 through the sampling branches 4 for detection, thereby obtaining the NOx concentration in the flue gas to be measured. The number and arrangement position of the sampling probes 3 are determined according to the number of groups and control arrangement of the upstream ammonia spraying grid of the denitrification outlet flue 1, as long as the area covered by the ammonia spraying grid corresponding to each sampling probe 3 is ensured to be substantially equal. At the same time, a sampling switching valve 5 is installed on each sampling branch pipe 4, and the opening or closing state of the sampling switching valve 5 on different sampling branch pipes 4 is adjusted so that the sampling probes 3 located at different positions in the denitrification outlet flue 1 extract the flue gas to be measured. Figure 1 As shown, a back-blowing component and a static eliminator are also provided downstream of the sampling branch pipe 4 along the flow direction of the flue gas to be measured. The back-blowing component is used to blow gas into the sampling branch pipe 4 at a pressure higher than the flue gas pressure to be measured in the sampling branch pipe 4, thereby preventing the flue gas to be measured carrying a large amount of dust from clogging the sampling branch pipe 4; the static eliminator 14 can ionize the gas into positive ions and negative ions, which are blown toward the sampling branch pipe under the back-blowing action of the back-blowing component and combined with the statically charged dust, thereby eliminating the static electricity of the dust and avoiding the problem of clogging the sampling branch pipe 4 due to static adsorption of dust.

[0026] Therefore, the anti-blocking NOx concentration zoning sampling and measuring device provided by the present application has multiple sampling probes 3 correspondingly connected to the sampling branch pipe 4, and the sampling switching valve 5 on the sampling branch pipe 4 is controlled to open and close, thereby controlling the corresponding sampling probe 3 to extract the flue gas to be measured from the denitrification outlet flue 1, and the flue gas flows through the sampling probe 3 and the sampling branch pipe 4 and enters the NOx analyzer 7, and the NOx concentration in the flue gas is obtained by the NOx analyzer 7. In addition, the backflush component is used to blow gas with a pressure higher than the flue gas pressure in the sampling branch pipe 4 to the sampling branch pipe 4, which can reduce the risk of blocking the sampling branch pipe 4 due to excessive dust content in the sampling branch pipe 4. Further, the static eliminator 14 is used to ionize the gas blown by the backflush component into positive ions and negative ions, which are blown to the sampling branch pipe 4 by the backflush component and combined with the statically charged dust in the sampling branch pipe 4, thereby eliminating the static electricity of the dust and preventing the dust from blocking the sampling branch pipe 4 due to static adsorption.

[0027] According to one embodiment of the anti-blocking NOx concentration zoning sampling and measuring device of the utility model, the number of NOx analyzers 7, backflush components and static eliminators 14 is multiple and the same as the number of sampling branch pipes 4, that is, a set of NOx analyzers 7, backflush components and static eliminators 14 is installed on each sampling branch pipe 4.

[0028] Or, alternatively, refer to Figure 1 As shown, the anti-blocking NOx concentration zone sampling and measuring device provided by the utility model also includes a sampling main pipe 6, the outlets of multiple sampling branch pipes 4 merge and are connected to the inlet of the sampling main pipe 6, the NOx analyzer 7 is installed on the sampling main pipe 6, and the backflush component and the static eliminator 14 are connected to the sampling main pipe 6. In this way, only one NOx analyzer 7, a backflush component and a static eliminator 14 are needed to detect the flue gas to be measured flowing out of different sampling branch pipes 4, and to blow high-pressure gas and positive and negative ions to different sampling branch pipes 4.

[0029] Optionally, refer to Figure 1 As shown, the anti-blocking NOx concentration zoning sampling and measuring device provided by the utility model also includes a negative pressure exhauster 9 installed on the sampling main pipe 6 and a sampling main valve 8 connected to the outlet of the sampling main pipe 6. The negative pressure exhauster 9 is arranged downstream of the NOx analyzer 7. The suction force generated by the negative pressure exhauster 9 is conducive to the sampling probe 3 to extract the flue gas in the denitrification outlet flue 1, and make the flue gas flow through the NOx analyzer 7 to complete the flue gas detection; the sampling main valve 8 can be used to control the start / close state of the sampling, and the outlet of the sampling main valve 8 is connected to the air preheater inlet flue 2, so that the flue gas after the measurement is completed flows into the air preheater inlet flue 2 through the sampling main valve 8 without polluting the environment.

[0030] Optionally, the minimum distance between the sampling branch pipe 4 and the sampling main pipe 6 and the flue wall does not exceed 20 cm to increase the temperature of the sampling branch pipe 4 and the sampling main pipe 6. It should be noted that the flue wall can be the outer wall of the denitrification outlet flue 1 and / or the air preheater inlet flue 2. Since high-temperature flue gas flows in the denitrification outlet flue 1 and the preheater inlet flue 2, the outer wall temperature of the denitrification outlet flue 1 and the preheater inlet flue 2 is relatively high. By installing the sampling branch pipe 4 and the sampling main pipe 6 close to the outer wall of the denitrification outlet flue 1 and the preheater inlet flue 2, the flue wall can heat the sampling branch pipe 4 and the sampling main pipe 6, so that the flue gas to be measured in the sampling branch pipe 4 and the sampling main pipe 6 can still maintain a relatively high temperature, preventing the formation of acid dew due to the decrease in the temperature of the flue gas to be measured. The acid dew is easy to adhere to dust, causing the dust to block the sampling branch pipe 4 and the sampling main pipe 6.

[0031] Optionally, refer to Figure 1 As shown, the anti-blocking NOx concentration zoning sampling and measuring device provided by the utility model also includes a back-blowing pipe 11 whose two ends are respectively connected to the back-blowing gas source 10 and the position of the sampling main pipe 6 located between the NOx analyzer 7 and the negative pressure exhauster 9, and the back-blowing component and the static eliminator 14 are installed on the back-blowing pipe 11. Specifically, the inlet of the back-blowing pipe 11 is connected to the back-blowing gas source 10, and the outlet is arranged at the downstream of the NOx analyzer 7 and the upstream position of the negative pressure exhauster 9. The static eliminator 14 is installed on the back-blowing pipe 11, which is conducive to the back-blowing component blowing the gas of the back-blowing gas source 10 and the positive and negative ions generated by the ionization of the static eliminator 14 to the sampling main pipe 6. At the same time, since the outlet of the back-blowing pipe 11 is arranged at the downstream of the NOx analyzer 7, the gas and positive and negative ions blown by the back-blowing component can flow through the NOx analyzer 7, thereby preventing the NOx analyzer 7 from being blocked by dust. The outlet of the back-blowing pipe 11 is arranged at the upstream position of the negative pressure exhauster 9, so that the moving stroke of the back-blowing gas can be shortened, thereby reducing the energy consumed by the back-blowing gas of the back-blowing assembly.

[0032] Alternatively, if Figure 1 As shown, the back-blowing assembly includes a back-blowing gas source driving mechanism and a back-blowing valve 12. The back-blowing valve 12 can be opened and closed automatically or manually.

[0033] Optionally, the back-blowing gas source driving mechanism includes an air pump, or, according to the anti-blocking NOx concentration zoning sampling and measuring device of the utility model, the back-blowing gas source driving mechanism includes a pulse generator 13. The pulse generator 13 can make the gas back-blown to the sampling main pipe 6 and the sampling branch pipe 4 generate stronger impact force and shear force, thereby better preventing the sampling main pipe 6 and the sampling branch pipe 4 from being blocked.

[0034] Optionally, the sampling probe 3 extends perpendicularly to the flue gas flow direction in the denitration outlet flue 1. Since the sampling probe 3 is perpendicular to the flue gas flow direction, a large amount of dust can be prevented from entering the sampling probe 3.

[0035] Furthermore, combined with Figure 1 As shown, the inlet of the sampling probe 3 extends into the denitration outlet flue 1 and extends to the central axis of the denitration outlet flue 1. In this way, it can be ensured that the flue gas extracted by the sampling probe 3 is more representative.

[0036] Reference Figure 1 As shown, according to a preferred embodiment of the utility model, the anti-blocking NOx concentration zoning sampling and measuring device includes multiple sampling probes 3, multiple sampling branch pipes 4, a sampling main pipe 6, a NOx analyzer 7, a backflush pipe 11, a negative pressure vacuum pump 9 and a sampling main valve 8, wherein the sampling probe 3 extends into the denitrification outlet flue 1 in a direction perpendicular to the flow direction of the flue gas in the denitrification outlet flue 1, and the inlet of the sampling probe 3 extends to the central axis position of the denitrification outlet flue 1, the inlet of the sampling branch pipe 4 is connected to the outlet of the sampling probe 3, the outlets merge and are connected to the inlet of the sampling main pipe 6, and a sampling switching valve 5 is installed on each sampling branch pipe 4. The sampling main pipe 6 is provided with a NOx analyzer 7 and a negative pressure exhauster 9 in sequence. The outlet of the sampling main pipe 6 is connected to the inlet of the sampling main valve 8, and the outlet of the sampling main valve 8 is connected to the air preheater inlet flue 2. Moreover, the sampling branch pipe 4 and the sampling main pipe 6 are installed close to the denitrification outlet flue 1 and the air preheater inlet flue 2. The sampling main pipe 6 is connected to a backflush pipe 11 at a position between the NOx analyzer 7 and the negative pressure exhauster 9. The inlet of the backflush pipe 11 is connected to a backflush gas source 10, and the outlet is connected to the sampling main pipe 6. A backflush valve 12, a pulse generator 13 and a static eliminator 14 are provided in sequence along the extension direction from the inlet to the outlet of the backflush pipe 11. The pulse generator 13 can blow the gas in the backflush gas source 10 and the positive and negative ions generated by the static eliminator 14 to the sampling main pipe 6 in the form of pulses. Therefore, the anti-blocking NOx concentration zoning sampling and measuring device provided by the utility model organically combines the wall-mounted heating installation of the sampling branch pipe 4 and the sampling main pipe 6, pulse backblowing and static elimination. The wall-mounted heating installation of the sampling branch pipe 4 and the sampling main pipe 6 can prevent the formation of acid dew and adhesion of dust after the flue gas to be measured is reduced in temperature. The pulse backblowing can enhance the disturbance effect of the backblowing. The static eliminator can eliminate the static electricity generated by the friction of the dust. The three are combined and complement each other, thereby more thoroughly solving the problem of sampling pipeline blockage.

[0037] The second aspect of the utility model provides an SCR denitration system, comprising the above-mentioned anti-blocking NOx concentration zoning sampling and measuring device.

[0038] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various specific technical features in any appropriate manner. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations. However, these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A blocking-proof NOx concentration zoning sampling and measuring device, characterized in that: include: A plurality of sampling probes (3), wherein the plurality of sampling probes (3) are used to extract flue gas to be measured from different positions in the denitrification outlet flue (1); A plurality of sampling branch pipes (4), wherein the plurality of sampling branch pipes (4) are connected to the corresponding sampling probe rods (3), and a sampling switching valve (5) is installed on the sampling branch pipe (4); A NOx analyzer (7), the NOx analyzer (7) being used to measure the concentration of NOx in the flue gas flowing out from the sampling branch pipe (4); a back-blowing assembly, the back-blowing assembly being arranged downstream of the sampling branch pipe (4) and being used for blowing gas into the sampling branch pipe (4) at a pressure higher than the flue gas pressure in the sampling branch pipe (4); and, An electrostatic eliminator (14) is arranged downstream of the sampling branch pipe (4), and the electrostatic eliminator (14) is configured to be able to ionize the gas into positive ions and negative ions.

2. The anti-blocking NOx concentration zoning sampling and measuring device according to claim 1 is characterized in that: It also includes a sampling main pipe (6), the outlets of the plurality of sampling branch pipes (4) merge and are connected to the inlet of the sampling main pipe (6), the NOx analyzer (7) is installed on the sampling main pipe (6), and the backflush assembly and the static eliminator (14) are connected to the sampling main pipe (6).

3. The anti-blocking NOx concentration zoning sampling and measuring device according to claim 2 is characterized in that: It also includes a negative pressure vacuum pump (9) installed on the sampling main pipe (6) and a sampling main valve (8) connected to the outlet of the sampling main pipe (6), and the negative pressure vacuum pump (9) is arranged downstream of the NOx analyzer (7).

4. The anti-blocking NOx concentration zoning sampling and measuring device according to claim 3 is characterized in that: The minimum distance between the sampling branch pipe (4) and the sampling main pipe (6) and the flue wall whose temperature is higher than that of the sampling branch pipe (4) and the sampling main pipe (6) is no more than 20 cm.

5. The anti-blocking NOx concentration zoning sampling and measuring device according to claim 3 is characterized in that: It also includes a backflush pipe (11) whose two ends are respectively connected to the backflush gas source (10) and the position of the sampling main pipe (6) located between the NOx analyzer (7) and the negative pressure exhauster (9), and the backflush assembly and the static eliminator (14) are installed on the backflush pipe (11).

6. The anti-blocking NOx concentration zoning sampling and measuring device according to claim 5 is characterized in that: The back-blowing assembly comprises a back-blowing gas source driving mechanism and a back-blowing valve (12).

7. The anti-blocking NOx concentration zoning sampling and measuring device according to claim 6 is characterized in that: The back-blowing gas source driving mechanism comprises a pulse generator (13).

8. The anti-blocking NOx concentration zoning sampling and measuring device according to claim 1 is characterized in that: The sampling probe (3) extends in a direction perpendicular to the flue gas flow direction in the denitration outlet flue (1).

9. The anti-blocking NOx concentration zoning sampling and measuring device according to any one of claims 1 to 8, characterized in that: The inlet of the sampling probe (3) extends into the denitrification outlet flue (1) and extends to the central axis of the denitrification outlet flue (1).

10. An SCR denitration system, characterized in that: It includes an anti-blocking NOx concentration zoning sampling and measuring device according to any one of claims 1-9.

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