An integrated sample gas assisted extraction and dilution module and its working method

Abstract

The present invention discloses an integrated sample gas assisted extraction dilution module and a working method thereof, wherein the dilution module comprises a filter, a jet pump, and a dilution unit integrated in a housing, wherein the housing is provided with a sample gas inlet, a standard gas and back-blowing interface, a zero gas inlet, and a mixed sample gas outlet, wherein the sample gas inlet is connected to the dilution unit through a filter, the zero gas inlet and the mixed sample gas outlet are both connected to the dilution unit, the sample gas inlet is connected to the jet pump through a number of extraction-assisted pipelines, and the sample gas inlet, the standard gas and back-blowing interface are connected. Based on this integrated module design, the entire dilution module can realize the heating function of all components with only one heating system, which greatly simplifies the heating structure of the system, reduces the probability of problems in the temperature control link of the system, improves the overall reliability of the system, and greatly reduces the volume of the dilution module.

Description

Technical Field

[0001] The invention relates to an integrated sample gas assisted extraction and dilution module and a working method thereof, belonging to the technical field of smoke monitoring systems. Background Art

[0002] Dilution method is a common way of sampling and processing gas in flue gas monitoring system.

[0003] The dilution method uses the principle of sonic orifice (also called critical orifice), that is, when there is a certain pressure difference before and after the orifice, when the fluid flows through the orifice, for a certain pore size, the flow rate through the orifice increases as the pressure difference increases. However, when the pressure difference exceeds a certain value (called the critical pressure difference), the flow rate of the fluid through the orifice shrinkage reaches the speed of sound. At this time, no matter how the pressure difference increases, the flow rate through the orifice will remain at a certain value and will no longer increase. Experiments have shown that the critical pressure difference for gas is 13inHg (about 44kPa).

[0004] The dilution method uses this principle to achieve constant-proportion dilution of the sample gas, that is, under the premise of controlling the zero gas pressure to be stable, the sample gas is diluted with zero gas at a constant proportion through the dilution unit.

[0005] The flue gas of coal-fired power plants contains a high amount of water. The water exists in the form of water vapor because of the high temperature in the flue. In addition to some in-situ or semi-in-situ measurement methods such as laser methods, other flue gas analysis instruments generally need to consider solving the problem of water condensation when the flue gas temperature drops. Among them, the dilution method is one of the commonly used sample gas processing methods.

[0006] The dilution method uses a very dry zero gas (the so-called zero gas, in addition to being dry, also does not contain the measured component) to dilute the flue gas with a high moisture content at a constant ratio. Through dilution, the water content of the diluted sample gas (mixed gas of sample gas + zero gas, also called mixed sample gas) is low enough to meet the requirements of non-heat transmission under outdoor conditions, and the water content is low enough not to damage the instrument.

[0007] Because the humidity of flue gas is very high, the dilution method is used to process the sample gas to meet the outdoor temperature, which generally requires a relatively high dilution. For example, for flue gas sampling at the SCR outlet, a dilution ratio of about 100 times is required to meet the winter environment in northern my country, so that the diluted sample gas can be transmitted to the instrument without condensation. Considering zero gas consumption, economy, etc., the sampling flow rate of the dilution method is usually small (generally 50 to 300 ml / min). Therefore, if the sample gas is extracted from the flue by the dilution unit alone, the sample gas replacement in the sampling pipeline is very slow, which will cause a delay in the measurement result. The longer the front-end pipeline of the dilution unit is, the greater the impact will be on the measurement system.

[0008] To solve this problem, in some actual engineering application sites, in order to accelerate the flow of flue gas and increase the sample gas replacement rate of dilution sampling, many will connect a jet pump to the outlet of the dilution unit to assist in suction, and use the drainage of the jet pump to accelerate the flow rate of the sample gas flowing through the dilution unit cavity.

[0009] However, when this external jet pump is used for flue gas sampling at the SCR outlet, because this section of flue gas contains ammonia (NH3) that escapes after denitration, and the flue gas also contains SO3 and extremely high water vapor, the temperature drop of the external pipeline and the jet pump position is difficult to avoid the generation of ammonium bisulfate (NH4HSO4), which leads to blockage and corrosion of metal parts. Or it is necessary to consider heating the external pipeline and the auxiliary jet pump, which increases the complexity and structural volume of the system. Summary of the invention

[0010] Purpose of the invention: In view of the problem that the traditional dilution module with an external auxiliary pump jet pump is prone to cause pipeline blockage when used at the SCR outlet, and greatly increases the difficulty of system heating, the present invention provides an integrated gas-assisted dilution module and a working method thereof. The module integrates components such as a jet pump, a filter, and a dilution unit into a shell to achieve a fully internal piping design, greatly simplifying the system's heating structure and effectively improving the overall reliability of the system.

[0011] Technical solution: To achieve the above-mentioned purpose, the present invention provides an integrated sample gas assisted extraction and dilution module, including a shell and a filter, a jet pump, and a dilution unit integrated in the shell. The shell is provided with a sample gas inlet, a standard gas and backblowing interface, a zero gas inlet, and a mixed sample gas outlet. The sample gas inlet is connected to the dilution unit through the filter, and the zero gas inlet and the mixed sample gas outlet are both connected to the dilution unit. The sample gas inlet is connected to the jet pump through a number of auxiliary extraction pipelines, and the sample gas inlet and the standard gas and backblowing interface are connected.

[0012] The working method of the integrated sample gas assisted extraction and dilution module includes: the sample gas enters from the sample gas inlet, a part of it is filtered through a filter and then passes into a dilution unit, and after being diluted in equal proportion, it is output from a mixed sample gas outlet, and the other part is assisted to be extracted to a jet pump through an auxiliary extraction pipeline.

[0013] Furthermore, the shell itself is a heat conductor, and a heat tracing component is arranged around the shell. Based on this integrated design, the dilution module can achieve the heat tracing function (stable, high temperature) of all components by using one heat tracing system.

[0014] Furthermore, the auxiliary pumping pipeline includes a first auxiliary pumping pipeline (i.e., a small auxiliary pumping pipeline), the first auxiliary pumping pipeline is connected between the filter and the jet pump, and a flow limiting pipe or a containerized needle valve is provided on the first auxiliary pumping pipeline to achieve the purpose of limiting or controlling the flow. The needle valve realizes throttling and flow limiting of the sample gas by reducing or increasing the valve core to change the diameter, while the diameter of the flow limiting pipe is fixed and cannot be adjusted.

[0015] The working method of the integrated sample gas assisted extraction and dilution module includes: the sample gas enters from the sample gas inlet, is filtered by the filter, a part of it is diluted in equal proportion by the dilution unit and then output from the mixed sample gas outlet, and the other part is assisted to be extracted to the jet pump after limiting the flow through the first auxiliary extraction pipeline.

[0016] Furthermore, the auxiliary suction pipeline also includes a second auxiliary suction pipeline (i.e., a large auxiliary suction pipeline), which is connected between the sample gas inlet and the jet pump. A high-temperature two-way valve is provided on the second auxiliary suction pipeline to realize the open / closed pipeline function, thereby realizing the selection of large and small flow auxiliary suction modes, and further realizing the sample gas auxiliary suction function with controllable flow.

[0017] The working method of the integrated sample gas assisted extraction and dilution module includes the following two working modes:

[0018] a. Small flow auxiliary pumping: The high-temperature two-way valve is closed, and the sample gas enters from the sample gas inlet. After being filtered by the filter, a part of it is diluted in equal proportion by the dilution unit and then output from the mixed sample gas outlet. The other part is limited by the first auxiliary pumping pipeline (i.e., the small auxiliary pumping pipeline) and then pumped to the jet pump;

[0019] b. Large flow rate auxiliary pumping: The high-temperature two-way valve is opened, and the sample gas enters from the sample gas inlet. A part of it is directly pumped to the jet pump through the second auxiliary pumping pipeline (i.e., the large auxiliary pumping pipeline), and the other part is filtered through the filter and then passed into the dilution unit and the first auxiliary pumping pipeline respectively. The sample gas passed into the dilution unit is diluted in equal proportion and then output from the mixed sample gas outlet. The sample gas passed into the first auxiliary pumping pipeline is pumped to the jet pump after flow limiting.

[0020] Furthermore, the filter is a tubular filter element structure sealed at both ends (unfiltered sample gas passes through the middle of the filter element, and the outer layer of the filter element is filtered sample gas), the second auxiliary extraction pipeline, the standard gas and the backblowing interface are connected to the same end of the inner hole of the filter element, the sample gas inlet is connected to the other end of the inner hole of the filter element, and the dilution unit and the first auxiliary extraction pipeline are respectively connected to the outer layer of the filter element.

[0021] In this way, the dilution unit and the small auxiliary extraction pipeline share a filter, realizing the full internal pipeline design while greatly reducing the volume of the dilution module. The filter is set in front of the small auxiliary extraction pipeline because the flow is limited to avoid impurities blocking the pipeline, while the large auxiliary extraction pipeline does not need to be set with a filter because it has a large pipeline diameter and is not easy to be blocked.

[0022] Furthermore, the jet pump adopts an integrated jet pump to meet the requirements of integrated design.

[0023] Beneficial effects: The integrated gas-assisted extraction and dilution module and the working method thereof provided by the present invention have the following advantages over the prior art:

[0024] 1. The integrated module design allows reliable and stable temperature control with only one heating system, which greatly simplifies the heating structure of the system, reduces the probability of problems in the temperature control link of the system, and reduces the possibility of ammonium bisulfate generation, thereby improving the overall reliability of the system and greatly reducing the volume of the dilution module.

[0025] 2. The sample gas auxiliary extraction function with controllable flow rates is realized to meet the demand for controllability of sample gas replacement speed when sampling by dilution method, providing strong guarantee for the realization of partition measurement system. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is the gas path schematic diagram of the traditional sample gas dilution module;

[0027] Figure 2 The gas circuit schematic diagram of the traditional sample gas dilution module with an external auxiliary jet pump;

[0028] Figure 3 It is a structural schematic diagram of an embodiment of the present invention;

[0029] Figure 4 is an internal schematic diagram of an embodiment of the present invention;

[0030] Figure 5 This is a gas circuit principle diagram of an embodiment of the present invention in a small flow rate auxiliary pumping mode;

[0031] Figure 6 This is a gas circuit principle diagram of an embodiment of the present invention in a large flow auxiliary pumping mode;

[0032] The reference numerals in the figure include: 1, sampling tube, 2, filter assembly, 3, dilution assembly, 4, zero gas interface, 5, mixed sample gas interface, 6, standard gas tube, 7, backflush tube, 8, jet pump,

[0033] 9. Housing, 10. Filter, 11. Integrated jet pump, 12. Dilution unit, 13. Sample gas inlet, 14. Standard gas and backflush interface, 15. Zero gas inlet, 16. Mixed sample gas outlet, 17. First auxiliary extraction pipeline, 18. Second auxiliary extraction pipeline, 19. Third auxiliary extraction pipeline, 20. Containerized needle valve, 21. High-temperature two-way valve. DETAILED DESCRIPTION

[0034] The preferred embodiments of the present invention will be described below in conjunction with the accompanying drawings to more clearly and completely illustrate the technical solutions of the present invention.

[0035] like Figure 1 As shown, the conventional sample gas dilution module comprises a sampling tube 1, a filter assembly 2, and a dilution assembly 3 which are connected in sequence. The filter assembly 2 is connected with a standard gas pipe 6 and a backflush pipe 7. The dilution assembly 3 has a relatively arranged zero gas interface 4 and a mixed sample gas interface 5. If the conventional dilution module is used to extract sample gas from the flue, the sample gas replacement in the sampling pipeline is very slow, which will cause a great delay in the measurement result.

[0036] like Figure 2 As shown, in order to accelerate the flow of flue gas and improve the sample gas replacement speed of dilution sampling, many will be connected to the traditional dilution module with an external jet pump 8 to accelerate the flow speed of the sample gas flowing through the dilution unit cavity by using the drainage of the jet pump 8. However, when this external jet pump is used for flue gas sampling at the SCR outlet, it is easy to cause sodium bisulfate to block and corrode the pipeline, and greatly increase the difficulty of system heating.

[0037] like Figure 3-4 As shown, based on the technical problems existing in the above-mentioned traditional sample gas dilution module plus an external auxiliary extraction jet pump, the present invention provides an integrated sample gas auxiliary extraction dilution module, including a shell 9 and a filter 10 integrated in the shell 9, an integrated jet pump 11, and a dilution unit 12 (arranged on the top of the filter 10). The shell 9 is provided with a sample gas inlet 13, a standard gas and backblowing interface 14, a zero gas inlet 15, and a mixed sample gas outlet 16. The sample gas inlet 13 is connected to the dilution unit 12 through the filter 10, and the zero gas inlet 15 and the mixed sample gas outlet 16 are both connected to the dilution unit 12. The sample gas inlet 13 is connected to the integrated jet pump 11 through a number of auxiliary extraction pipelines.

[0038] Furthermore, the shell 9 itself is a heat conductor, and a heating component is arranged around the shell 9. In this embodiment, the heating component can be a hollowed-out aluminum block and a heating element, that is, the shell is placed in a hollowed-out aluminum block, and then a heating element (including a heating plate, a heating rod, etc.) is arranged in the aluminum block to conduct heat to the shell. In other embodiments, the heating component can also be a customized heating tank (a cast aluminum part with a heating pipe inside), etc.

[0039] In this embodiment, the auxiliary suction pipeline includes a first auxiliary suction pipeline 17, a second auxiliary suction pipeline 18, and a third auxiliary suction pipeline 19. The first auxiliary suction pipeline 17 is connected between the filter 10 and the third auxiliary suction pipeline 19, the second auxiliary suction pipeline 18 is connected between the sample gas inlet 13 and the third auxiliary suction pipeline 19, and the third auxiliary suction pipeline 19 is connected to the jet pump 11.

[0040] Furthermore, a flow limiting pipe or a containerized needle valve 20 is provided on the first auxiliary pumping pipeline 17 to achieve the function of limiting or controlling the flow; a high-temperature two-way valve 21 is provided on the second auxiliary pumping pipeline 18 to achieve the function of opening / closing the pipeline.

[0041] In this embodiment, the filter 10 is a tubular filter structure with sealed ends (unfiltered sample gas flows in the middle of the filter, and the outer layer of the filter is filtered sample gas), the second auxiliary extraction pipeline 18, the standard gas and back-blowing interface 14 are connected to the same end of the filter inner hole, the sample gas inlet 13 is connected to the other end of the filter inner hole, and the dilution unit 12 and the first auxiliary extraction pipeline 17 are respectively connected to the outer layer of the filter. In this way, the dilution unit and the small auxiliary extraction pipeline share a filter, and the full internal pipeline design is realized while greatly reducing the volume of the dilution module.

[0042] Furthermore, the dilution unit 12 includes a microporous tube (also called a flow limiting tube, a sonic tube) and a jet pump. The air inlet of the jet pump is connected to the zero gas inlet 15. One end of the microporous tube is connected to the outer layer of the filter element, and the other end is connected to the air outlet of the jet pump and the mixed sample gas outlet 16. In this way, a pressure difference is generated at both ends of the microporous tube to achieve proportional dilution.

[0043] Furthermore, the jet pump 11 adopts an integrated jet pump 11 to meet the integrated design requirements.

[0044] Based on the working method of the above-mentioned integrated sample gas assisted extraction and dilution module, there are two working modes:

[0045] a. Low flow rate pumping: Figure 5 As shown, the high-temperature two-way valve 21 is closed, and the sample gas enters from the sample gas inlet 13. After being filtered by the filter 10, a part of it is diluted in equal proportion by the dilution unit 12 and then transported to the instrument from the mixed sample gas outlet 16 for measurement, and the other part is pumped to the integrated jet pump 11 through the first auxiliary pumping pipeline 17 (small auxiliary pumping pipeline) and the third auxiliary pumping pipeline 19;

[0046] b. Large flow rate pumping: Figure 6 As shown, the high-temperature two-way valve 21 is opened, and the sample gas enters from the sample gas inlet 13. One part is directly pumped to the integrated jet pump 11 through the second auxiliary pumping pipeline 18 (large auxiliary pumping pipeline) and the third auxiliary pumping pipeline 19, and the other part is filtered through the filter 10 and respectively passed into the dilution unit 12 and the first auxiliary pumping pipeline 17. The sample gas passed into the dilution unit 12 is diluted in equal proportion and then transported from the mixed sample gas outlet 16 to the instrument for measurement. The sample gas passed into the first auxiliary pumping pipeline 17 is pumped to the integrated jet pump 11 through the third auxiliary pumping pipeline 19.

[0047] The large flow auxiliary extraction can ensure that the sample gas of each channel is replaced simultaneously during mixed measurement in the partition measurement system. At the same time, after each patrol measurement, the sample gas in all partition sample gas pipelines is quickly replaced with the sample gas required for the next patrol measurement.

[0048] The partition measurement system realizes synchronous sampling and asynchronous measurement by patrolling the sample gas locked in the front-end pipeline of each partition, thereby realizing real-time measurement. Considering the contamination of the front and back ends and the replacement of the sample gas in the internal cavity of the instrument, we need to accurately control the flow rate of the sample gas during single-partition measurement, so we need to use a smaller flow rate for drainage.

[0049] The above-mentioned integrated sample gas assisted extraction and dilution module has two assisted extraction channels, a high-temperature two-way valve is set in the large flow channel, and a flow limiting tube or needle valve is set in the small flow channel, so as to finally realize the assisted extraction demand of two controllable flow rates. In other embodiments, more than two channels of sample gas assisted extraction and more than two flow rates of sample gas assisted extraction can be realized according to the idea of ​​this design.

[0050] The above specific implementations are only descriptions of the preferred implementations of the present invention, and do not limit the protection scope of the present invention. Without departing from the design concept and spirit of the present invention, various modifications, substitutions and improvements made by ordinary technicians in this field to the technical solution of the present invention based on the text description and drawings provided by the present invention should all fall within the protection scope of the present invention.

Claims

1. An integrated sample gas assisted extraction and dilution module, characterized in that: It includes a shell and a filter, a jet pump and a dilution unit integrated in the shell. The shell is provided with a sample gas inlet, a standard gas and back-blowing interface, a zero gas inlet and a mixed sample gas outlet. The sample gas inlet is connected to the dilution unit through the filter, the zero gas inlet and the mixed sample gas outlet are both connected to the dilution unit, the sample gas inlet is connected to the jet pump through a plurality of auxiliary extraction pipelines, and the sample gas inlet and the standard gas and back-blowing interface are connected; the shell itself is a heat conductor, and a heating component is arranged around the shell; The auxiliary pumping pipeline includes a first auxiliary pumping pipeline and a second auxiliary pumping pipeline, the first auxiliary pumping pipeline is connected between the filter and the jet pump, a flow limiting pipe or a containerized needle valve is arranged on the first auxiliary pumping pipeline, the second auxiliary pumping pipeline is connected between the sample gas inlet and the jet pump, and a high-temperature two-way valve is arranged on the second auxiliary pumping pipeline; The filter is a tubular filter element structure with sealed ends; the second auxiliary extraction pipeline, the standard gas and the back-blowing interface are connected to the same end of the filter element inner hole; the sample gas inlet is connected to the other end of the filter element inner hole; the dilution unit and the first auxiliary extraction pipeline are respectively connected to the outer layer of the filter element.

2. The integrated sample gas assisted extraction and dilution module according to claim 1, characterized in that: The jet pump adopts an integrated jet pump.

3. A working method based on the integrated sample gas assisted extraction and dilution module according to claim 1, characterized in that: include: The sample gas enters from the sample gas inlet, part of it is filtered through the filter and then passes into the dilution unit, and then is output from the mixed sample gas outlet after being diluted in equal proportion, and the other part is assisted by the extraction pipeline to the jet pump.

4. A working method based on the integrated sample gas assisted extraction and dilution module according to claim 1, characterized in that: include: The sample gas enters from the sample gas inlet, is filtered by the filter, a part of it is diluted in equal proportion by the dilution unit and then output from the mixed sample gas outlet, and the other part is limited by the first auxiliary pumping pipeline and then pumped to the jet pump.

5. A working method based on the integrated sample gas assisted extraction and dilution module according to claim 1, characterized in that: The following working modes are included: a. Low flow rate auxiliary pumping: The high temperature two-way valve is closed, and the sample gas enters from the sample gas inlet. After being filtered by the filter, a part of it is diluted in equal proportion by the dilution unit and then output from the mixed sample gas outlet. The other part is limited by the flow of the first auxiliary pumping pipeline and then pumped to the jet pump; b. Large flow rate auxiliary pumping: The high-temperature two-way valve is opened, and the sample gas enters from the sample gas inlet. A part of it is directly pumped to the jet pump through the second auxiliary pumping pipeline, and the other part is filtered through the filter and then passed into the dilution unit and the first auxiliary pumping pipeline respectively. The sample gas passed into the dilution unit is diluted in equal proportion and then output from the mixed sample gas outlet. The sample gas passed into the first auxiliary pumping pipeline is pumped to the jet pump after flow limiting.

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