Continuous sampling device and method for flue gas of thermal power plant

Abstract

The invention provides a continuous sampling device and method for flue gas of a thermal power plant, and the device comprises a sampling assembly which comprises a plurality of sampling main pipes which are detachably connected and a heat tracing assembly which is wound on the plurality of sampling main pipes; a filter head is arranged on each sampling main pipe and is used for filtering flue gas step by step; the annular gas chamber is communicated with the connecting end of the sampling assembly; the intelligent anti-blocking and pulse back-blowing system comprises a control unit, a high-speed airflow guide pipe and a plurality of nozzles, the high-speed airflow guide pipe is communicated with the annular air chamber, and the nozzles are communicated with the annular air chamber and the connecting end of the sampling assembly. In the implementation mode, the control unit responds to too high pressure of the sampling main pipe and controls the high-speed airflow guide pipe to provide high-pressure gas to be reversely blown towards the sampling assembly through the multiple nozzles. A multi-stage filtering structure is adopted, smoke can be filtered stage by stage, and the burden of the filtering head is greatly relieved; the intelligent anti-blocking and pulse blowback system realizes'on-demand blowback ', and ensures the continuity of data acquisition to the greatest extent.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of flue gas sampling, in particular to a continuous sampling device and method for flue gas of a thermal power plant. BACKGROUND

[0002] With the increasing global concern about climate change and the proposal of China's double-carbon goal of "carbon peak and carbon neutrality", it is crucial to accurately and continuously monitor the CO2 emissions of industrial fixed sources, especially thermal power plants as the main body of carbon emissions. Accurate CO2 concentration data is not only the basis for evaluating the total emissions of power plants and accounting for carbon tax / carbon trading quotas, but also a key parameter for optimizing combustion efficiency, evaluating and controlling the performance of carbon capture, utilization and storage systems.

[0003] Currently, the mainstream technology for online monitoring of flue gas components in thermal power plants is the extraction type continuous emission monitoring system. The working principle of this system is to extract a representative part of the flue gas sample through a sampling probe inserted into the flue, and after pre-treatment (such as dust removal, moisture removal, cooling, etc.), it is sent to the back-end analysis instrument for analysis, thereby obtaining CO2 concentration data.

[0004] The sampling probe, as the "first pass" of the entire monitoring system, directly determines the representativeness of the obtained flue gas sample and the accuracy of the subsequent analysis results. The flue gas environment in thermal power plants is extremely harsh, usually with high temperature, high humidity, and high dust. Therefore, how to obtain flue gas samples in a harsh environment for a long time, stably and reliably is one of the core problems that need to be solved in flue gas online monitoring technology.

[0005] The related sampling probe has the following defects, which leads to poor effect in actual application, which is specifically shown in: (1) Most of the related sampling probes adopt a single-stage filtering structure, i.e. only a filter element is arranged at the front end of the probe. This design faces a dilemma: if the filter element aperture is large, the filtering precision is insufficient, and fine dust will penetrate the filter element, polluting and clogging the subsequent slender sampling pipeline and analysis instrument; if the filter element aperture is small, although the filtering precision can be improved, the surface will be quickly covered and killed by large-particle fly ash in a high-dust environment, leading to more frequent clogging.

[0006] (2) Insufficient anti-condensation measures, root problem not solved: the condensation of water vapor and acidic substances in flue gas is the root cause of "wet clogging" and equipment corrosion. The heating measures in existing technologies are often local and incomplete. For example, some probes only heat the front-end filtering part, ignoring the sampling main pipe inside the probe. When the flue gas passes through the hot filter element, it still undergoes temperature drop and condensation when entering the sampling main pipe with relatively low temperature.

[0007] (3) The reverse blowing mode is inefficient and not intelligent: The traditional reverse blowing system usually adopts a simple mode of direct reverse blowing from the center of the sampling pipe. The coverage of a single gas flow is limited, and it is easy to form "blowout dead angles" on the filter element, which cannot uniformly and comprehensively clean the entire filter surface. For sticky "wet mud-like" deposits formed due to condensation, this reverse blowing mode is even more inadequate. Fixed time periods are mostly used for reverse blowing, which cannot respond to the actual clogging of the probe. This leads to unnecessary reverse blowing when the smoke density is low, interrupting effective data collection and wasting energy, and lacking an intelligent prediction mechanism based on real-time conditions such as pipeline pressure difference.

[0008] Therefore, the prior art has obvious deficiencies in filter structure, anti-condensation design, reverse blowing cleaning efficiency and intelligence, and there is an urgent need for a highly integrated design that integrates staged filtration, full-range temperature control and efficient intelligent reverse blowing, to fundamentally solve the technical problems of easy clogging, difficult maintenance and inaccurate data of the CO2 sampling probe for flue gas in thermal power plants. SUMMARY

[0009] The summary part of the present application is used to introduce the concepts in a simple form, which will be described in detail in the specific embodiments part. The summary part of the present application is not intended to identify key features or essential features of the claimed technical solution, nor is it intended to limit the scope of the claimed technical solution.

[0010] Some embodiments of the present application provide a continuous sampling device and method for flue gas in thermal power plants to solve the technical problems mentioned in the background part.

[0011] In a first aspect, some embodiments of the present application provide a continuous sampling device for flue gas in thermal power plants, comprising: A sampling assembly comprising a plurality of sampling main pipes connected detachably and a heat tracing assembly wound on the plurality of sampling main pipes; each sampling main pipe is provided with a filter head, and the pore sizes of the plurality of filter heads gradually decrease in the direction away from the open end of the sampling assembly for step-by-step filtration of flue gas; An annular air chamber in communication with the connection end of the sampling assembly; An intelligent anti-clogging and pulse reverse blowing system comprising a control unit, a high-speed airflow conduit and a plurality of nozzles; the high-speed airflow conduit is in communication with the annular air chamber, and the plurality of nozzles are in communication with the annular air chamber and the connection end of the sampling assembly; the control unit controls the high-speed airflow conduit to provide high-pressure gas for reverse blowing from the plurality of nozzles towards the sampling assembly.

[0012] In a second aspect, some embodiments of the present application provide a continuous sampling method for flue gas in thermal power plants, comprising: The control unit controls the high-speed airflow guide pipe to provide high-pressure gas for back blowing operation for a preset time length in response to the pressure value of the sampling main pipe exceeding the preset pressure value. If the pressure value of the sampling main pipe still exceeds the preset pressure value, the back blowing operation is repeated until the pressure value of the sampling main pipe is lower than the preset pressure value. The flue gas is sampled by the sampling assembly.

[0013] The above embodiments of the present application have the following beneficial effects: 1. The multistage filtering structure can filter large particles and fine particles step by step, greatly reducing the burden of the filter head. This hierarchical cooperative working mode not only ensures the cleanliness of the final output flue gas and protects the rear-end analysis instrument, but more importantly, significantly improves the overall pollution carrying capacity and anti-blocking performance of the device, thereby greatly prolonging the working life and manual maintenance period of the device.

[0014] 2. The constant temperature control of the multiple sampling main pipes is realized by the heating assembly, effectively preventing the formation of condensate with high viscosity and strong corrosion, and further improving the anti-blocking performance of the device.

[0015] 3. The intelligent anti-blocking and pulse back blowing system realizes "on-demand back blowing" according to the pressure of the sampling main pipe, thereby saving energy and maximizing the continuity of data acquisition. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings needed to be used in the specific embodiments or prior art description. Obviously, the drawings described below are some embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without creative labor.

[0017] Figure 1 is a structural schematic view of an embodiment of the continuous sampling device for flue gas of a thermal power plant of the present application; Figure 2 is a sectional view of an embodiment of the nozzle of the present application; Figure 3 is a structural schematic view of an embodiment of multiple nozzles of the present application; Figure 4 is a flowchart of some embodiments of the continuous sampling method for flue gas of a thermal power plant according to the present disclosure.

[0018] Explanation of reference signs: 1, primary filter head; 2, primary sampling main; 3, heating assembly; 4, air pressure sensor; 5, secondary filter head; 6, connecting sleeve; 7, secondary sampling main; 8, nozzle; 9, annular air chamber; 10, high-speed air flow conduit. DETAILED DESCRIPTION

[0019] The technical solutions of the present application will be described in detail below with reference to the embodiments. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0020] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0021] In addition, the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, "a plurality of" means two or more, unless otherwise explicitly specified. In addition, the terms "mounting", "connecting", "connecting" should be broadly understood, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be the communication between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0022] The present disclosure will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0023] First, please refer to Figures 1 to 3 The continuous sampling device for flue gas of a thermal power plant of the present application comprises a sampling assembly, an annular air chamber 9, and an intelligent anti-blocking and pulse backwashing system.

[0024] The above-mentioned sampling assembly comprises a primary sampling main 2 and a secondary sampling main 7 connected together, and the open end of the primary sampling main 2 is connected to the inlet of the annular air chamber 9. Figure 1The first-stage filter head 1 is arranged at the right end of the sampling assembly, and the second-stage filter head 5 is arranged between the first-stage sampling main pipe 2 and the second-stage sampling main pipe 7. Specifically, the first-stage sampling main pipe 2 and the second-stage sampling main pipe 7 are connected by the connecting sleeve 6, and the second-stage filter head 5 is arranged in the connecting sleeve 6.

[0025] The connecting sleeve 6 is used to connect the first-stage sampling main pipe 2 and the second-stage sampling main pipe 7, which can reduce the maintenance cost. Specifically, when the first-stage sampling main pipe 2 needs to be replaced, the connecting sleeve 6 is only needed to be disassembled, and only the first-stage sampling main pipe 2 needs to be replaced, without the need to replace the entire sampling assembly.

[0026] The second-stage filter head 5 is arranged in the connecting sleeve 6, and when the second-stage filter head 5 needs to be replaced, the connecting sleeve 6 is only needed to be disassembled, and the operation can be performed. Therefore, the efficiency and convenience of maintenance are improved.

[0027] When sampling the flue gas, the first-stage filter head 1 directly contacts the high-temperature flue gas of the thermal power plant, and the first-stage filter head 1 is made of a high-temperature-resistant and corrosion-resistant material. The first-stage filter head 1 performs rough filtration on the entering flue gas, so as to block the large-particle fly ash and dust in the flue gas outside the first-stage filter head 1. The pore size of the first-stage filter head 1 can be determined according to the particle size of the large-particle matter in the flue gas of the thermal power plant.

[0028] Next, the flue gas that has undergone rough filtration carries fine particles and passes through the first-stage sampling main pipe 2 and the second-stage filter head 5. The second-stage filter head 5 performs fine filtration on the flue gas, so as to efficiently capture and filter out the fine particles. In this way, the flue gas is treated into clean gas that meets the analysis standard. The pore size of the second-stage filter head 5 is smaller than that of the first-stage filter head 1, and the pore size of the second-stage filter head 5 can be determined by repeated experiments by those skilled in the art.

[0029] The above technical solution adopts a two-stage filtration structure of rough filtration and fine filtration, respectively intercepts large-particle matter and captures fine particles, so as to optimize the filtration efficiency and pollution capacity, reduce the risk of blockage, and prolong the maintenance period. The cooperation of the first-stage filter head 1 and the second-stage filter head 5 ensures the cleanliness of the flue gas, reduces the load of the second-stage filter head 5, and improves the reliability of the device.

[0030] Although the above and Figure 1 Although the above and

[0031] A heat tracing component 3 is uniformly wound along the length of the sampling component. This heat tracing component 3 continuously heats the sampling component, ensuring that its internal temperature is consistently maintained above the water dew point and acid dew point of the flue gas. This fundamentally eliminates the possibility of condensation of the flue gas inside the sampling component, effectively preventing the formation of corrosive and highly viscous condensates from water vapor and acidic gases such as SO2 due to cooling. As an example, the heat tracing component 3 can be an electrically heated heating tape, with temperature controlled by a connected external temperature control system. As another example, the heat tracing component 3 can also be a steam heating pipe; those skilled in the art can choose according to the actual situation.

[0032] The connection end of the above-mentioned secondary sampling main pipe 7 ( Figure 1 The left end (the exhaust end) is connected to the annular chamber 9, into which clean gas enters. The exhaust end of the annular chamber 9 is connected to the analytical instrument, and an electrically controlled valve can be installed on this exhaust end. When the electrically controlled valve opens, clean gas is discharged from the annular chamber 9 and enters the analytical instrument, thereby obtaining the concentration data of gases such as CO2.

[0033] To promptly detect blockages in the sampling components and perform backflushing operations, the device also includes an intelligent anti-blocking and pulse backflushing system. This system comprises multiple nozzles 8, a high-speed airflow duct 10, two pressure sensors 4, and a control unit.

[0034] Multiple nozzles 8 are connected to the connection end of the secondary sampling main pipe 7 and the annular gas chamber 9, and the high-speed airflow duct 10 is connected to the annular gas chamber 9. A pressure sensor 4 is installed on both the primary sampling main pipe 2 and the secondary sampling main pipe 7, and this pressure sensor 4 is communicatively connected to the control unit. The aforementioned high-speed airflow duct 10 is also equipped with a solenoid valve that is communicatively connected to the control unit.

[0035] As an example, the control unit mentioned above can be an MCU (Microcontroller Unit), a PLC (Programmable Logic Controller), a DSP (Digital Signal Processor), etc.

[0036] In operation, the two pressure sensors 4 collect the pressure values ​​of their respective sampling main pipes and transmit them to the control unit. The control unit compares these pressure values ​​with preset pressure values. When the pressure value exceeds the preset pressure value, it indicates that either the primary sampling main pipe 2 or the secondary sampling main pipe 7 is blocked. Next, the control unit closes the electrically controlled valve of the annular chamber 9 and opens the solenoid valve. High-pressure, high-speed, dry, and clean gas supplied by the gas tank rushes into the annular chamber 9 and is sprayed into the sampling main pipes through multiple nozzles 8. This backflushing operation cleans the dust adhering to the primary sampling main pipe 2, the secondary sampling main pipe 7, the primary filter head 1, and the secondary filter head 5.

[0037] Furthermore, each nozzle 8 can be configured as a venturi tube. When gas enters each nozzle 8, the throat in the middle of the nozzle 8 can further increase the gas flow rate. In this way, a negative pressure zone can be formed around the gas when it is ejected, further enhancing the suction and stripping effect on the attached dust and strengthening the cleaning ability.

[0038] The cross-sections of the aforementioned multiple nozzles 8 can be arranged in a honeycomb pattern, thereby converting the gas into multiple high-speed pulse jets of kinetic energy, which are concentrated and sprayed toward the sampling main pipe, thus achieving the cleaning effect on the sampling main pipe.

[0039] Finally, after the aforementioned backflushing operation has reached the preset time, the control unit closes the solenoid valve and continues sampling of the flue gas. The preset time can be a relatively short period, which can be determined by those skilled in the art based on the actual situation.

[0040] The aforementioned intelligent anti-clogging and pulse backflushing system monitors the pressure value of the sampling pipeline in real time through the air pressure sensor 4, and only performs backflushing when the pressure value exceeds the preset pressure value, realizing backflushing on demand. Compared with the traditional timed backflushing operation, it is more targeted and intelligent, can save energy, and maximizes the continuity of data acquisition.

[0041] The pulse jet formed by the instantaneously released high-pressure gas has powerful impact kinetic energy, providing excellent removal of sticky and hard deposits formed by condensation and crystallization. Furthermore, the nozzle 8, based on the Venturi principle, enhances cleaning capabilities through negative pressure suction, ensuring efficient and thorough backflushing.

[0042] This application also provides a continuous sampling method for flue gas from thermal power plants, which can be used with the sampling devices described in the above embodiments. For example... Figure 4 The diagram shows a flowchart 400 of an embodiment of the continuous sampling method for flue gas in a thermal power plant provided by the present invention. The method may include the following steps: Step 401: In response to the pressure value of the sampling main pipe exceeding the preset pressure value, the control unit controls the high-speed airflow duct 10 to provide high-pressure gas for a preset duration of backflushing operation.

[0043] In some embodiments, the execution entity of this method is a control unit, such as a PLC. Taking 1 as an example, the pressure sensor 4 installed on the primary sampling main pipe 2 and the secondary sampling main pipe 7 collects pressure values ​​and transmits them to the control unit.

[0044] The control unit compares the pressure value with the preset pressure value. When the pressure value is greater than the preset pressure value, it indicates that the primary sampling main pipe 2 or the secondary sampling main pipe 7 is blocked.

[0045] Next, the control unit closes the electrically controlled valve of the annular chamber 9 and opens the solenoid valve. High-pressure, high-speed, dry, and clean gas supplied by the gas tank rushes into the annular chamber 9 and is sprayed into the sampling main pipe through multiple nozzles 8, which can perform a backflushing operation on the sampling components. This cleans the dust adhering to the primary sampling main pipe 2, the secondary sampling main pipe 7, the primary filter head 1, and the secondary filter head 5.

[0046] Finally, after the aforementioned backflushing operation has reached the preset time, the control unit closes the solenoid valve and continues sampling of the flue gas. The preset time can be a relatively short period, which can be determined by those skilled in the art based on the actual situation.

[0047] Step 402: If the pressure value of the sampling tube still exceeds the preset pressure value, repeat the backflushing operation until the pressure value of the sampling tube is lower than the preset pressure value.

[0048] In some embodiments, after the backflushing operation is completed, the sampling component continues to sample the flue gas, and the aforementioned pressure sensor 4 continues to collect pressure values ​​and transmit them to the control unit. If the collected pressure value still exceeds the preset pressure value, the backflushing operation is repeated until the pressure value of the sampling main pipe is lower than the preset pressure value.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A continuous sampling device for flue gas in thermal power plants, characterized in that, include: The sampling assembly includes multiple detachably connected sampling main pipes and a heat tracing assembly wound around the multiple sampling main pipes; each sampling main pipe is provided with a filter head, and the aperture of the multiple filter heads gradually decreases along the direction away from the open end of the sampling assembly, for filtering flue gas in stages. An annular gas chamber is connected to the sampling component's connection end; The intelligent anti-clogging and pulse backflush system includes a control unit, a high-speed airflow duct, and multiple nozzles; the high-speed airflow duct is connected to an annular air chamber, and the multiple nozzles are connected to the annular air chamber and the connection end of the sampling component; in response to excessive pressure in the sampling main pipe, the control unit controls the high-speed airflow duct to provide high-pressure gas for backflush towards the sampling component from the multiple nozzles.

2. The continuous sampling device for flue gas in thermal power plants according to claim 1, characterized in that, Multiple sampling heads, including a primary sampling head and a secondary sampling head, are provided, and a primary filter head is provided at the open end of the sampling component. A secondary filter head is provided between the primary sampling head and the secondary sampling head.

3. The continuous sampling device for flue gas in thermal power plants according to claim 1, characterized in that, The two adjacent sampling tubes are detachably connected by a connecting sleeve.

4. The continuous sampling device for flue gas in thermal power plants according to claim 3, characterized in that, The filter head is installed inside the connecting sleeve.

5. The continuous sampling device for flue gas in thermal power plants according to claim 1, characterized in that, The heating assembly is used to continuously heat the sampling main pipe, so that its internal temperature is maintained above the water dew point and acid dew point of the flue gas.

6. The continuous sampling device for flue gas in thermal power plants according to claim 1, characterized in that, Each nozzle is configured with a venturi tube structure; the cross-section of multiple nozzles is honeycomb-shaped.

7. The continuous sampling device for flue gas in thermal power plants according to claim 1, characterized in that, Each sampling tube is equipped with a pressure sensor that communicates with the aforementioned control unit.

8. The continuous sampling device for flue gas in thermal power plants according to claim 7, characterized in that, The high-speed airflow duct is equipped with a solenoid valve that is communicatively connected to the control unit.

9. The continuous sampling device for flue gas in thermal power plants according to claim 8, characterized in that, When the pressure value collected by the pressure sensor exceeds the preset pressure value, the control unit opens the solenoid valve, causing high-pressure gas to backflush from multiple nozzles toward the sampling component.

10. A method for using the continuous sampling device for flue gas from a thermal power plant as described in any one of claims 1-9, characterized in that, The method includes: The control unit responds when the pressure value of the sampling main pipe exceeds the preset pressure value, and controls the high-speed airflow duct to provide high-pressure gas for a preset backflushing operation; If the pressure value of the sampling tube still exceeds the preset pressure value, repeat the backflushing operation until the pressure value of the sampling tube is lower than the preset pressure value.

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