Air volume measuring system for primary air duct at inlet of coal mill of coal-fired power generation unit

Abstract

The utility model provides an air volume measuring system of a primary air duct at an inlet of a coal mill of a coal-fired generating set. Comprising a hot air volume measuring sensor and a hot air flow computer connected with the hot air volume measuring sensor, wherein the hot air volume measuring sensor is arranged on at least one data average air speed point position in a cross section of a primary hot air duct except a primary hot air isolating gate and a primary hot air adjusting damper before communication with the primary cold air duct; a cold air quantity measuring sensor and a cold air flow computer connected with the cold air quantity measuring sensor are respectively or integrally arranged at at least one data average air speed point position in one cross section of the primary cold air duct except the position of the primary cold air adjusting air door; and the flow accumulation computer is used for gathering the output flows of the hot air flow computer and the cold air flow computer. After being accumulated by the flow accumulation computer, the data are sent to the unit control system; the problem of inaccurate air volume measurement of the primary air duct at the inlet of the coal mill is solved. The temperature controllability of the coal mill is improved, the fire occurrence probability is reduced, and the unit operation safety, flexibility and energy-saving and environment-friendly performance are improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of air volume measurement, relates to an air volume measurement system, and particularly relates to an air volume measurement system for a primary air duct at an inlet of a coal mill of a coal-fired generator set. Background Art

[0002] like Figure 1 As shown in the figure, it is a schematic diagram of the air volume measurement sensor setting of the primary air duct at the inlet of a coal mill of a 330MW coal-fired power generation unit. The primary hot air (temperature 230℃, pressure 5kPa) comes out from the primary hot air square main air duct 001 (primary hot air main duct), passes through the upper horizontal straight pipe section 003 (square cross-section, width 1500mmX height 1200mm) and the primary hot air isolation gate door 002 in series, passes through the downward upper right-angle elbow 004, enters the primary hot air regulating damper 005 (three-leaf door), and then passes through the vertical straight pipe section 006 with a length of about 2D, and at the same time, the circular air duct 009 (DN600, called the primary cold air straight pipe section) vertically connected thereto enters the cold air (temperature 20℃, pressure 10kPa), passes through the lower right-angle elbow 007 and the lower horizontal straight pipe section 008 to be mixed with the hot air and then enters the coal mill. Since the existing air volume measurement sensor is located in the lower horizontal straight pipe section 008 before the coal mill inlet after the primary hot air and the primary cold air are mixed: 1) the primary hot air duct diameter change, upper right-angle elbow 004, lower right-angle elbow 007, shorter straight pipe sections (upper horizontal straight pipe section 003, vertical straight pipe section 006, lower horizontal straight pipe section 008), primary hot air regulating damper 005, primary hot air isolation gate door 002 and other factors in the primary air duct interfere too much, resulting in very uneven temperature and wind fields; 2) the primary cold air vertically enters the primary hot air duct, resulting in serious wind and temperature fields of the mixed air after mixing. There is no regularity at all; 3) The existing air volume measurement sensor is installed in the lower horizontal straight pipe section 008 behind the lower right-angle elbow 007 of the primary mixing air duct. The serious interference of the primary cold air to the primary hot air in the measurement of wind speed, temperature and pressure has not disappeared. The lower right-angle elbow 007 makes the primary mixed air turn, making it more difficult to accurately measure the air volume; therefore, there is serious turbulence in the wind field of this section of the duct, the mixing temperature is uneven, and the wind speed, temperature and pressure are all unstable. The existing measurement technology cannot solve the problem of accurate air volume measurement. This is a problem existing in the air volume measurement of the primary air duct at the inlet of the pulverizer of all coal-fired power generation units. Summary of the invention

[0003] In order to solve the problem of inaccurate measurement of the air volume in the primary air duct at the inlet of the coal-fired generator set, the utility model provides an air volume measurement system capable of accurately measuring the air volume in the primary air duct at the inlet of the coal-fired generator set, wherein the primary air duct at the inlet of the coal-fired generator set comprises a primary hot air duct connected to the primary hot air main duct with a variable diameter, a primary cold air duct and a primary mixing air duct connected to the coal-fired generator set coal pulverizer; the primary hot air duct comprises a primary hot air isolation damper door and a primary hot air regulating damper, the primary cold air duct comprises a primary cold air regulating damper, the primary air mixing duct inlet and the primary cold air duct outlet are respectively connected to the primary hot air duct outlet; the air volume measurement system comprises: a hot air volume measurement sensor is respectively or integrally arranged at at least one data average wind speed point in a cross section of the primary hot air duct except the positions of the primary hot air isolation damper door and the primary hot air regulating damper before being connected to the primary cold air duct, and a hot air flow computer connected thereto;

[0004] A cold air volume measurement sensor and a cold air flow computer connected thereto are respectively or integrally arranged at at least one data average wind speed point in a cross section of the primary cold air duct except the position of the primary cold air regulating damper;

[0005] and a flow accumulation computer for summarizing the output flows of the hot air and cold air flow computers.

[0006] Preferably, a hot air volume measurement sensor is separately or integrally arranged at a position of a cross section of a primary hot air duct having at least one data average wind speed point: in the primary hot air duct in front of a primary hot air regulating damper.

[0007] Preferably, the hot air volume measurement sensor is separately or integrally arranged at a position of a cross section of a primary hot air duct having at least one data average wind speed point: in the primary hot air duct between a primary hot air regulating damper and a primary hot air isolation gate door.

[0008] Preferably, the primary hot air duct between the primary hot air regulating damper and the primary hot air isolation gate door also includes a hot air straight pipe section; a hot air volume measurement sensor is separately or integrally arranged at a position of a cross section of the primary hot air duct having at least one data average wind speed point: in the hot air straight pipe section.

[0009] Preferably, the cold air volume measurement sensor is separately or integrally arranged at a position of a cross section of a primary cold air duct having at least one data average wind speed point: in the primary cold air duct in front of a primary cold air regulating damper.

[0010] Preferably, the primary cold air duct in front of the primary cold air regulating damper also includes a cold air straight pipe section; the cold air volume measurement sensor is separately or integrally arranged at a position of a cross section of the primary cold air duct having at least one data average wind speed point: in the cold air straight pipe section.

[0011] Preferably, the hot air volume measurement sensor or the cold air volume measurement sensor respectively set up is a Pitot tube type air volume measurement sensor or a Venturi type air volume measurement sensor or an unpowered fan air volume measurement sensor; the hot air volume measurement sensor or the cold air volume measurement sensor set up as a whole is a non-uniformly distributed Basque type air volume measurement sensor.

[0012] Preferably, the Pitot tube type air volume measurement sensor or the Venturi type air volume measurement sensor or the non-uniformly distributed Venturi type air volume measurement sensor is provided with a back-purge device.

[0013] Preferably, the Venturi-type air volume measurement sensor is a single-throat diameter tube air volume measurement sensor, a double-throat diameter tube air volume flow sensor or a multi-throat diameter tube air volume measurement sensor.

[0014] Preferably, the unpowered fan air volume measurement sensor includes an unpowered fan and a rotation speed measurement unit for monitoring the unpowered fan; the unpowered fans may be of the same specifications or different specifications.

[0015] The utility model respectively sets or overall sets a hot air volume measuring sensor at at least one data average wind speed point in a cross section of the primary hot air duct except the primary hot air isolation damper door and the primary hot air regulating damper position before being connected with the primary cold air duct, and respectively sets or overall sets a cold air volume measuring sensor at at least one data average wind speed point in a cross section of the primary cold air duct except the primary cold air regulating damper position; the flow is accumulated by a flow accumulation computer and then sent to the unit control system, thereby greatly improving the accuracy of the air volume measurement of the primary air duct entering the coal mill inlet; in this way, not only the temperature controllability of the coal mill is improved and the probability of fire is reduced, but also the overall operation safety, flexibility, energy saving and environmental protection of the coal-fired power generation unit are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the structure of the air volume measurement sensor at the primary air duct at the inlet of a coal mill of a 330MW coal-fired power generation unit.

[0017] Figure 2 Embodiment 1 provides a schematic diagram of the overall structure of an air volume measurement sensor arranged in a primary air duct at an inlet of a coal mill of a coal-fired power generation unit;

[0018] Figure 3 yes Figure 2The schematic diagram of the structure of the air volume measurement sensor installation position in a cross section of a primary hot air duct is shown;

[0019] Figure 4 yes Figure 2 The schematic diagram of the structure of the air volume measurement sensor installation position in a cross section of a primary cold air duct is shown;

[0020] Figure 5 yes Figure 3 Or the schematic diagram of the cross-sectional structure of the non-uniformly distributed type air volume measurement sensor body shown in 4;

[0021] Figure 6 yes Figure 2 A schematic diagram of the structure of an air volume measurement system is shown;

[0022] Figure 7 It is a corresponding curve diagram of the given flow rate of the simulated air duct and the opening of the primary hot air regulating damper;

[0023] Figure 8 It is a graph of the flow rate measured by the hot air uneven distribution type air volume measurement sensor and the opening of the primary hot air regulating damper.

[0024] Description of the numbers in the figure:

[0025] 001. primary hot air square main air duct, 002. primary hot air isolation gate, 003. upper horizontal straight pipe section, 004. upper right-angle elbow, 005. primary hot air regulating damper, 006. vertical straight pipe section, 007. lower right-angle elbow, 008. lower horizontal straight pipe section, 009. primary cold air straight pipe section, 010. primary cold air regulating damper; 1. hot air non-uniform distribution type air volume measurement sensor, 2. cold air non-uniform distribution type air volume measurement sensor, 3. primary hot air duct wall, 4. primary cold air duct wall; 01. rectifier grille, 02. negative pressure sampling hole, 03. negative pressure cavity, 04. positive pressure sampling hole, 05. positive pressure cavity. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with the accompanying drawings and specific implementations; it should be understood that the following specific implementations are only used to illustrate the present invention and are not used to limit the scope of the present invention. Example 1

[0027] like Figure 2 , 3, 4 and 5 are schematic diagrams of the structure of an air volume measurement system for a primary air duct at the inlet of a coal mill of a 330MW coal-fired power generation unit provided in this embodiment; the primary air duct at the inlet of the coal mill of the coal-fired power generation unit includes a primary hot air duct, a primary cold air duct and a primary mixing duct connected to a primary hot air square main air duct 001 with a diameter change; the primary hot air duct includes an upper horizontal straight pipe section 003 and a primary hot air isolation gate 002, an upper right-angle elbow 004, a primary hot air regulating damper 005, and a vertical straight pipe section 006 in series along the hot air flow direction; the primary cold air duct branch is connected to the lower end side of the vertical straight pipe section 006, including a primary cold air straight pipe section 009 and a primary cold air regulating damper 010 connected in series therein; the primary mixing air duct includes a lower right-angle elbow 007 and a lower horizontal straight pipe section 008 connected to the lower port of the vertical straight pipe section.

[0028] The air volume measurement system comprises:

[0029] A hot air volume measuring sensor is respectively arranged at at least one data average wind speed point in a certain cross section of the upper horizontal straight pipe section after the primary hot air regulating damper 005 (that is, a hot air non-uniformly distributed air volume measuring sensor 1 (probe) is arranged at the two or three data average wind speed points, and the two or three data average wind speed points are respectively arranged at the corresponding positions of the hot air non-uniformly distributed air volume measuring sensor 1.), and a hot air flow computer connected thereto; a cold air volume measuring sensor is respectively arranged at at least one data average wind speed point in a certain cross section of the primary cold air straight pipe section 009 before the primary cold air regulating damper 010 (a cold air non-uniformly distributed air volume measuring sensor 2 (probe) is jointly arranged at the two or three data average wind speed points, and the two or three data average wind speed points are respectively arranged at the corresponding positions of the cold air non-uniformly distributed air volume measuring sensor 2), and a cold air flow computer connected thereto; and a flow accumulation computer that summarizes the output flows of the hot and cold air flow computers.

[0030] like Figure 5As shown, it is a schematic diagram of the main cross-sectional structure of the hot air or cold air uneven distribution type air volume measurement sensor 1 or 2; its upper end pipe is a negative pressure pipe with a shuttle-shaped appearance, which includes a negative pressure chamber 03 and a negative pressure sampling hole 02 arranged on its inner rear cavity wall; its lower end pipe is a positive pressure pipe with a shuttle-shaped appearance that is mirror-symmetrical to the upper end pipe, which includes a positive pressure chamber 05 and a positive pressure sampling hole 04 arranged on its inner front cavity wall; the upper and lower end pipes are connected together by a number of rectifying grid pieces 01, and in the middle of them is a fluid flow channel consisting of a large hole for fluid inlet-a small hole in the middle-a large hole for fluid outlet. At least one data average wind speed value point is set at a close position between two adjacent rectifying grid pieces on the hot air or cold air non-uniformly distributed air volume measurement sensor 1 or 2; when two or three data average wind speed value points are set, it is only necessary to set the two or three data average wind speed value points at a close position between two adjacent rectifying grid pieces on the hot air or cold air non-uniformly distributed air volume measurement sensor 1 or 2 as much as possible.

[0031] According to Figure 1 The simulated wind tunnel is established based on the arrangement of the primary air duct structure equipment shown in the figure, and the simulation experiment process is as follows (the method for determining the data average wind speed value point set in the cross section is based on the method for determining the data average wind speed value point in the cross section of the air duct in a non-uniformly distributed wind field according to Chinese patent CN2022112805951):

[0032] A wind tunnel simulated real flow calibration test was carried out on the cross section where the existing air volume measurement sensor is installed (i.e., the lower horizontal straight pipe section 008). Under different wind speed (load) conditions, no common data average wind speed point at all different wind speeds with industrial measurement accuracy was found in this cross section, which also proves that it is unscientific to install the existing air volume measurement sensor in this cross section, and also explains that the primary air volume measurement structure of the prior art is inaccurate. In addition, since the primary cold air enters the primary hot air duct at 90°, it has a great influence on the air volume measurement. Therefore, the existing air volume measurement sensor installation position (lower horizontal straight pipe section 008) is not suitable for the installation of the air volume measurement device.

[0033] The determination of the specific cross-sectional location of the hot or cold air uneven distribution type air volume measurement sensor is carried out through simulation. Figure 1The experiment on the primary air duct has drawn the only basic feasible conclusion: the primary hot air and the primary cold air are measured and calculated separately, and then added together to achieve accurate measurement of the mixed air volume; 1) Since the straight pipe section in front of the primary cold air regulating damper 010 in the primary cold air straight pipe section 009 is long and has little turbulence, the cold air volume measurement sensor (i.e., the cold air non-uniformly distributed bar-type air volume measurement sensor) is directly installed in the air duct area in front of the primary cold air regulating damper, and is connected to a cold air flow computer for measurement and calculation; 2) There are two optional positions for the hot air volume measurement sensor (i.e., the hot air non-uniformly distributed bar-type air volume measurement sensor) in the air duct area: one is after the primary hot air regulating damper and before the cold air enters the entrance of the primary hot air duct; the other is on the upper horizontal straight pipe section 003 behind the primary hot air isolation gate door 002.

[0034] The specific installation position of the hot air volume measurement sensor needs to be determined by a wind tunnel simulation test: according to the method of determining the average wind speed value point in the cross section of the wind duct in a non-uniformly distributed wind field according to Chinese patent CN2022112805951:

[0035] (1) The hot air volume measurement sensor is installed in the vertical straight pipe section 006 before the cold air enters the entrance of the primary hot air duct after the primary hot air regulating damper. The simulation experiment verifies the following: According to the big data measurement and analysis calculation results, according to the loads of 100%, 85%, 70%, 55%, 40% and 25% of the opening of the primary hot air regulating damper, the average wind speed of the data of 396 points sampled under each load is calculated. The results show that the average wind speed of the data is not linearly related to the opening of the primary hot air regulating damper, and there is an inverse trend phenomenon, indicating that the deflected flow caused by the turning of the primary hot air regulating damper makes it impossible for the hot air volume measurement sensor to measure accurately, and the hot air regulating damper interferes with its accurate measurement. Therefore, the vertical straight pipe section 006 before the cold air enters the entrance of the primary hot air duct after the primary hot air regulating damper, although its length is very long, is not suitable for installing the hot air volume measurement sensor (it is not the best position).

[0036] (2) The hot air volume measurement sensor is installed in the upper horizontal straight pipe section 003 behind the primary hot air isolation gate 002. The simulation experiment verifies as follows:

[0037]

[0038] Note: The detected wind speed values ​​in the table are calculated based on the differential pressure values ​​measured by the non-uniformly distributed air volume measurement sensor combined with factors such as hot air temperature, differential pressure and pressure.

[0039] The corresponding curve between the given flow rate of the simulated air duct and the opening of the hot air regulating damper is as follows: Figure 7 shown.

[0040] The curve of the hot air uneven distribution air flow measurement sensor measuring the flow rate and the opening of the primary hot air regulating damper, such as Figure 8 shown.

[0041] Since the primary hot air regulating damper has a sealing protruding surface, it affects the measured value when it is fully open; therefore, according to the above simulation experiment results, the hot air volume measurement sensor is installed at the upper horizontal straight pipe section 003 between the primary hot air isolation gate door 002 and the upper right-angle elbow 004.

[0042] Of course, the hot air or cold air volume measurement sensor described in this embodiment can use the above-mentioned non-uniformly distributed Venturi type air volume measurement sensor; such as single-throat tube, double-throat tube, multi-throat tube and other air volume measurement sensors; Pitot tube type air volume measurement sensor can also be used.

[0043] Since the hot air volume measurement sensor in this embodiment is installed in the dust air duct, a back-purge device for measuring gas pipelines in Chinese patent CN111520611A can be used to solve the problem of inaccurate duct volume measurement caused by dust blocking the air volume measurement sensor. Example 2

[0044] The air volume measurement system for the primary air duct at the inlet of the coal mill of a coal-fired power generation unit provided in this embodiment is an improvement on the embodiment 1. The difference between the embodiment 1 and the embodiment 1 is as follows:

[0045] A hot air non-powered fan air volume measurement sensor is respectively set at at least one data average wind speed point in a certain cross-section of the upper horizontal straight pipe section after the primary hot air regulating damper 005; a cold air non-powered fan air volume measurement sensor is respectively set at at least one data average wind speed point in a certain cross-section of the primary cold air straight pipe section before the primary cold air regulating damper; and hot and cold air flow computers and flow accumulation computers which respectively monitor the hot air and cold air non-powered fan air volume measurement sensors.

[0046] The hot air or cold air unpowered fan air volume measurement sensor includes an unpowered fan and a speed measurement unit for monitoring the fan, such as the German Testo (TESTO) TESTO410-1 mini anemometer;

[0047] According to the wind speed of the data average wind speed point, the unpowered fans can be selected with the same specifications or different specifications. In addition, the air volume measurement system of the primary air duct at the inlet of the coal mill of the coal-fired power generation unit provided in this embodiment does not have the problem of dust blockage, so there is no need to set a back-purge device for measuring the gas pipeline in Chinese patent CN111520611A. The rest of the parts and their working principles are basically similar to those of Example 1.

[0048] The heat air volume measurement sensor is set at the optimal measurement position. Figure 2As shown, in principle, a hot air volume measurement sensor can be set in any cross section of a primary hot air duct as long as at least one data average wind speed point can be obtained within the allowable range of industrial air volume measurement error, such as setting it in the primary hot air duct except for the primary hot air regulating damper and the primary hot air isolation gate door before the primary cold air enters the primary hot air duct, or setting it in the primary hot air duct except for the primary hot air isolation gate door before the primary hot air regulating damper, or setting it in the primary hot air duct except for the primary hot air isolation gate door before the upper right-angle elbow except for the primary hot air isolation gate door. Similarly, the setting position of the cold air volume measurement sensor in the present invention is the optimal measurement position, such as Figure 2 As shown, in principle, a cold air volume measurement sensor can be set in any cross-section of the primary cold air duct as long as at least one data average wind speed point can be obtained within the allowable range of industrial air volume measurement error, such as setting it in the primary cold air straight pipe section except the primary cold air regulating damper position, or setting it in the primary cold air straight pipe section in front of the primary cold air regulating damper.

[0049] Although the above embodiment is based on the actual specific structure of the primary air duct at the inlet of the coal mill of a specific 330MW coal-fired power generation unit in a power plant as an example to illustrate the present invention, it should be understood that the invention point of the utility model is: before being connected with the primary cold air duct, at least one data average wind speed point in a cross section of the primary hot air duct except the position of the primary hot air isolation gate and the primary hot air regulating damper is respectively set or as a whole to set a hot air volume measurement sensor, and a hot air flow computer connected thereto; at least one data average wind speed point in a cross section of the primary cold air duct except the position of the primary cold air regulating damper is respectively set or as a whole to set a cold air volume measurement sensor, and a cold air flow computer connected thereto. Flow computer; the hot air or cold air flow computer measures the air volume value in real time and sends it to the DCS control system of the coal-fired generator set after accumulation through the flow accumulation computer; its function is to solve the problem of inaccurate air volume measurement in the primary air duct at the inlet of the coal mill of the coal-fired generator set, and greatly improve the accuracy of the air volume measurement in the air duct entering the coal mill; in this way, not only the temperature controllability of the coal mill is improved, the probability of fire is reduced, but also the overall operation safety, flexibility, energy saving and environmental protection of the coal-fired generator set are improved; those skilled in the art may make changes or improvements to the present invention without departing from the essential spirit and scope of the above-mentioned inventive points of the present invention, but they should all fall within the protection scope of the technical solution of the present invention.

Claims

1. A system for measuring the air volume of a primary air duct at the inlet of a coal-fired power generation unit coal mill, wherein the primary air duct at the inlet of the coal-fired power generation unit coal mill comprises a primary hot air duct connected to a primary hot air main duct with a variable diameter, a primary cold air duct and a primary mixing duct connected to the coal-fired power generation unit coal mill; the primary hot air duct comprises a primary hot air isolation damper door and a primary hot air regulating damper, the primary cold air duct comprises a primary cold air regulating damper, the primary air mixing duct inlet and the primary cold air duct outlet are respectively connected to the primary hot air duct outlet; characterized in that, The air volume measurement system comprises: A hot air volume measurement sensor is separately or integrally arranged at at least one data average wind speed point in a cross section of the primary hot air duct except for the primary hot air isolation damper door and the primary hot air regulating damper before being connected with the primary cold air duct, and a hot air flow computer connected thereto is also arranged; A cold air volume measurement sensor and a cold air flow computer connected thereto are respectively or integrally arranged at at least one data average wind speed point in a cross section of the primary cold air duct except the position of the primary cold air regulating damper; and a flow accumulation computer for summarizing the output flows of the hot air and cold air flow computers.

2. The air volume measurement system according to claim 1, characterized in that: The hot air volume measurement sensor is separately or integrally arranged at a position of a cross section of a primary hot air duct having at least one data average wind speed point: in the primary hot air duct in front of a primary hot air regulating damper.

3. The air volume measurement system according to claim 2, characterized in that: The hot air volume measurement sensor is separately or integrally arranged at a position of a cross section of a primary hot air duct having at least one data average wind speed point: in the primary hot air duct between the primary hot air regulating damper and the primary hot air isolation gate door.

4. The air volume measurement system according to claim 3, characterized in that: The primary hot air duct between the primary hot air regulating damper and the primary hot air isolation gate also includes a hot air straight pipe section; a hot air volume measurement sensor is separately or integrally arranged at a position of a cross section of the primary hot air duct having at least one data average wind speed point: in the hot air straight pipe section.

5. The wind volume measurement system according to claim 1, 2, 3 or 4, characterized in that: The cold air volume measurement sensor is separately or integrally arranged at a position of a cross section of the primary cold air duct having at least one data average wind speed point: in the primary cold air duct in front of the primary cold air regulating damper.

6. The air volume measurement system according to claim 5, characterized in that: The primary cold air duct in front of the primary cold air adjustment door also includes a cold air straight pipe section; a cold air volume measurement sensor is separately or integrally arranged at a position of a cross section of the primary cold air duct having at least one data average wind speed point: in the cold air straight pipe section.

7. The wind volume measurement system according to claim 1 or 2 or 3 or 4 or 6, characterized in that: The hot air volume measurement sensor or the cold air volume measurement sensor respectively set up may be a Pitot tube type air volume measurement sensor, a Venturi type air volume measurement sensor or a non-powered fan air volume measurement sensor; the hot air volume measurement sensor or the cold air volume measurement sensor set up as a whole may be a non-uniformly distributed Ba-type air volume measurement sensor.

8. The air volume measurement system according to claim 7, characterized in that: The Pitot tube type air volume measurement sensor or the Venturi type air volume measurement sensor or the non-uniform distribution type air volume measurement sensor is provided with a back-purge device.

9. The air volume measurement system according to claim 7, characterized in that: The Venturi type air volume measurement sensor is a single-throat diameter tube air volume measurement sensor, a double-throat diameter tube air volume flow sensor or a multi-throat diameter tube air volume measurement sensor.

10. The air volume measurement system according to claim 5, characterized in that: The hot air volume measurement sensor or the cold air volume measurement sensor respectively set up may be a Pitot tube type air volume measurement sensor, a Venturi type air volume measurement sensor or a non-powered fan air volume measurement sensor; the hot air volume measurement sensor or the cold air volume measurement sensor set up as a whole may be a non-uniformly distributed Ba-type air volume measurement sensor.

11. The air volume measurement system according to claim 10, characterized in that: The Pitot tube type air volume measurement sensor or the Venturi type air volume measurement sensor or the non-uniform distribution type air volume measurement sensor is provided with a back-purge device.

12. The air volume measurement system according to claim 10, characterized in that: The Venturi type air volume measurement sensor is a single-throat diameter tube air volume measurement sensor, a double-throat diameter tube air volume flow sensor or a multi-throat diameter tube air volume measurement sensor.

13. The air volume measurement system according to claim 7, characterized in that: The unpowered fan air volume measurement sensor comprises an unpowered fan and a rotation speed measurement unit for monitoring the unpowered fan; the unpowered fans can be of the same specification or different specifications.

14. The air volume measurement system according to claim 10, characterized in that: The unpowered fan air volume measurement sensor comprises an unpowered fan and a rotation speed measurement unit for monitoring the unpowered fan; the unpowered fans can be of the same specification or different specifications.

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