Differential pressure flowmeter based on multi-point sampling measurement structure

Abstract

The utility model discloses a differential pressure flow meter based on a multipoint sampling measurement structure type. The differential pressure flow meter comprises a total pressure sampler, a total pressure pipe and a static pressure pipe, the total-pressure sampler is L-shaped, an inlet of the total-pressure sampler faces the incoming flow direction and is connected with the total-pressure pipe through the total-pressure sampler communicating pipe, the back face of the total-pressure pipe is the static pressure pipe, and the static pressure holes of the static pressure pipe correspond to the total-pressure sampler communicating pipe in a one-to-one mode. According to the L-shaped total pressure sampler, impurities and condensed water can be discharged in time, ash blocking is not prone to occurring, and stable and accurate operation of online flow monitoring can be achieved.

Description

Technical Field

[0001] The utility model belongs to the technical field of coal-fired power generation, and particularly relates to a differential pressure flowmeter based on a multi-point sampling measurement structure type. Background Technique

[0002] The induced draft fan of a coal-fired power plant is one of the key devices to ensure the normal combustion of a boiler or other combustion equipment. By online monitoring the flow rate of the induced draft fan, its working state can be adjusted in real time, the combustion efficiency can be improved, the fuel consumption can be reduced, and the operation efficiency of the whole power plant can be enhanced. With the increasingly strict environmental protection regulations, power plants need to monitor and report the pollutants they emit more strictly. The online monitoring of the induced draft fan flow rate, as part of the whole monitoring system, can ensure that the power plant can accurately and timely report its flue gas emission situation and meet the relevant regulatory requirements. At the same time, the online monitoring of the induced draft fan flow rate can accurately control the emission volume and emission speed of flue gas, help to adjust the combustion parameters, reduce the generation and emission of pollutants, ensure that the flue gas emission of the power plant meets the national or local environmental protection standards, and reduce the environmental protection risk.

[0003] The induced draft fan of a coal-fired power plant is usually arranged in the high-temperature and high-dust environment of the boiler tail flue. Such harsh environmental conditions pose severe challenges to the stability and reliability of the flow measurement device. In order to improve the accuracy of the online monitoring data of the flow rate and reduce the degree of easy blockage, the utility model optimizes the structure type of the flow measurement device to improve the accuracy of the flow rate test.

[0004] The essence of flue gas flow measurement is velocity measurement, and the actual flue gas flow is obtained based on the average velocity and cross-sectional area of the flue duct section. Among them, the average velocity of the flue duct section is obtained by averaging the velocities at representative points or representative lines and then making reasonable corrections according to theoretical analysis and on-site calibration. Currently, the commonly used measurement methods include the differential pressure method and the ultrasonic method. The differential pressure method belongs to the representative point measurement method, mainly using a Pitot tube, and the S-type Pitot tube has relatively high accuracy, and is arranged in a single-point or multi-point manner according to the flow field distribution; the ultrasonic method belongs to the representative line measurement, and calculates the flue gas velocity on the measurement line by using the time difference between the ultrasonic wave propagating along the flow and against the flow. Content of the Utility Model

[0005] Taking into comprehensive consideration factors such as the types of flue gas media, the size of the on-site flue duct, and the flue gas velocity in a coal-fired power plant, the utility model proposes a differential pressure flowmeter based on a multi-point sampling measurement structure type. The designed L-type total pressure sampler can timely discharge impurities and condensate water, is not easy to be blocked by ash, and can realize stable and accurate operation of online flow monitoring.

[0006] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0007] A differential pressure flowmeter based on a multi-point sampling measurement structure type, comprising a total pressure sampler, a total pressure pipe, and a static pressure pipe;

[0008] The total pressure sampler is in an L shape, the inlet of the total pressure sampler faces the oncoming flow direction, the total pressure pipe is connected through the total pressure sampler connecting pipe, the back of the total pressure pipe is the static pressure pipe, and the positions of the static pressure holes of the static pressure pipe correspond one by one to the total pressure sampler connecting pipes.

[0009] A further improvement of the present utility model lies in that the aperture R2 of the total pressure sampler is not less than 10 mm.

[0010] A further improvement of the present utility model lies in that if the dust content in the raw flue gas is lower than 30 mg / Nm during more than half of the operation time of the power plant 3 then R2 = 10 mm, otherwise R2 = 15 mm.

[0011] A further improvement of the present utility model lies in that the inlet of the total pressure sampler faces the oncoming flow direction, wherein the length L1 of the oncoming flow pipe = 2R2.

[0012] A further improvement of the present utility model lies in that the turning radius R1 of the total pressure sampler = 1.5R2, and the length L2 of the outlet pipe section of the total pressure sampler = 1.5R2.

[0013] A further improvement of the present utility model lies in that the length L3 of the total pressure sampler connecting pipe = R2.

[0014] A further improvement of the present utility model lies in that the static pressure pipe and the total pressure pipe are arranged side by side, and the radii R3 = R4 = 1.5R2 of the static pressure pipe and the total pressure pipe.

[0015] A further improvement of the present utility model lies in that two total pressure pipes and two static pressure pipes in the horizontal and vertical directions are respectively arranged on a single flue gas pipeline cross-section, and the number n of total pressure samplers is set according to the flue size L in each direction.

[0016] A further improvement of the present utility model lies in that when the flue size L ≥ 1000 mm, the number n of total pressure samplers = L / 25R2, and 3 ≤ n ≤ 8.

[0017] A further improvement of the present utility model lies in that when the flue size L ≤ 1000 mm, the number n of total pressure samplers = 3.

[0018] The present utility model has at least the following beneficial technical effects:

[0019] The differential pressure flowmeter based on the multi-point sampling measurement structure type provided by the present utility model sets an appropriate number of total pressure samplers according to the pipeline size to achieve multi-point sampling and reduce errors. At the same time, the present utility model sets the total pressure sampler as an L shape and sets a total pressure sampler connecting pipe. On the one hand, it realizes the sampling of the total pressure, and on the other hand, it can discharge dust, water vapor, etc. in the flue gas through the outlet of the L-shaped total pressure sampler, and can solve the blockage problem. Brief Description of the Drawings

[0020] Figure 1 It is a schematic structural diagram of the differential pressure flowmeter based on the multi-point sampling measurement structure type of the present utility model;

[0021] Figure 2 It is a schematic structural size diagram of the differential pressure flowmeter based on the multi-point sampling measurement structure type of the present utility model.

[0022] Description of the Reference Numerals in the Drawings:

[0023] 1. Total pressure sampler; 2. Total pressure pipe; 3. Static pressure pipe; 4. Total pressure sampler inlet; 5. Total pressure sampler outlet; 6. Total pressure sampler connecting pipe. Specific Embodiments

[0024] In the following, only some exemplary embodiments are simply described. As those skilled in the art can recognize, the described embodiments can be modified in various different ways without departing from the spirit or scope of the present utility model. Therefore, the drawings and the description are considered to be exemplary in nature rather than restrictive.

[0025] In the description of the present utility model, 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", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation of the present utility model.

[0026] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present utility model, "a plurality" means two or more unless otherwise specifically defined.

[0027] In the present utility model, unless otherwise clearly stipulated and defined, terms such as "installation", "connection", "linkage", "fixation" shall 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 a communication connection; it can be a direct connection, or an indirect connection through an intermediate medium, and can be the communication inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0028] In the present utility model, unless otherwise clearly stipulated and defined, the first feature being "above" or "below" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through other features therebetween. Moreover, the first feature being "above", "over" and "on the top of" the second feature includes that the first feature is directly above and obliquely above the second feature, or merely indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "beneath" and "under the bottom of" the second feature includes that the first feature is directly below and obliquely below the second feature, or merely indicates that the horizontal height of the first feature is lower than that of the second feature.

[0029] It should also be understood that the terms used in the description of the present utility model are only for the purpose of describing specific embodiments and are not intended to limit the present utility model. As used in the description of the present utility model and the appended claims, unless otherwise clearly indicated by the context, the singular forms of "a", "an" and "the" are intended to include the plural forms.

[0030] It should be further understood that the term " / and" used in the description of the present utility model and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0031] Structural schematic diagrams according to the disclosed embodiments of the present utility model are shown in the drawings. These figures are not drawn to scale, where for the purpose of clear expression, some details are enlarged and some details may be omitted. The shapes of various regions and layers shown in the figures and their relative sizes and positional relationships are only exemplary, and may actually deviate due to manufacturing tolerances or technical limitations, and those skilled in the art can design regions / layers with different shapes, sizes and relative positions according to actual needs.

[0032] The embodiments of the present utility model will be described in detail below with reference to the drawings.

[0033] Embodiment 1

[0034] As Figure 1As shown in the figure, a differential pressure flowmeter based on a multi-point sampling measurement structure type provided in this embodiment is characterized by including a total pressure sampler 1, a total pressure pipe 2, and a static pressure pipe 3;

[0035] The total pressure sampler 1 is in an L shape. The total pressure sampler inlet 4 faces the oncoming flow direction and is connected to the total pressure pipe 2 through a total pressure sampler connecting pipe 6. The back of the total pressure pipe 2 is the static pressure pipe 3, and the positions of the static pressure holes of the static pressure pipe 3 correspond one-to-one with the total pressure sampler connecting pipe 6.

[0036] Embodiment 2

[0037] As Figure 1 shown in the figure, a differential pressure flowmeter based on a multi-point sampling measurement structure type provided in this embodiment includes a total pressure sampler 1, a total pressure pipe 2, and a static pressure pipe 3; the total pressure sampler 1 is designed in an L shape; the total pressure sampler inlet 4 faces the oncoming flow direction and is connected to the total pressure pipe 2 through a total pressure sampler connecting pipe 6 to collect total pressure data, and the direction of the total pressure sampler outlet 5 is the same as that of the total pressure pipe 2; part of the flue gas carries flue gas impurities and water vapor and flows out through the total pressure sampler outlet 5; the back of the total pressure pipe 2 is the static pressure pipe 3, and the positions of the static pressure holes correspond one-to-one with the total pressure sampler connecting pipe 6.

[0038] In this embodiment, the value of R2 is determined according to the dust content of the raw flue gas. Considering factors such as installation space, the smaller the sampling measurement structure, the better, but considering problems such as blockage, the size of R2 cannot be too small. Therefore, if the dust content of the raw flue gas is less than 30 mg / Nm during more than half of the operation time of the power plant 3 then R2 = 10 mm, otherwise R2 = 15 mm.

[0039] In this embodiment, the structural parameters of the total pressure sampler 1 are as follows: the total pressure sampler inlet 4 faces the oncoming flow direction, the length of the oncoming flow pipe L1 = 2R2, the turning radius of the total pressure sampler 1 R1 = 1.5R, the length of the total pressure sampler outlet pipe section L2 = 1.5R2, and the length of the total pressure sampler connecting pipe 6 L3 = R2.

[0040] In this embodiment, the static pressure pipe 3 and the total pressure pipe 2 are arranged in parallel, and the radii of the static pressure pipe 3 and the total pressure pipe 2 R3 = R4 = 1.5R2.

[0041] In this embodiment, two total pressure pipes 2 and static pressure pipes 3 in the horizontal and vertical directions are respectively arranged on the cross-section of a single flue gas pipeline, and the number n of total pressure samplers 1 is set according to the flue duct size L in each direction. When the flue duct size L ≥ 1000 mm, the number n of total pressure samplers 1 = L / 25R2, and n ≤ 8; when the flue duct size L ≤ 1000 mm, the number n of total pressure samplers 1 = 3.

[0042] In this embodiment, further, the flue gas flow rate can be calculated according to the total pressure and static pressure data of the measurement surface where the total pressure sampler 1 is located, and the formula is as follows.

[0043]

[0044] Wherein:

[0045] Q represents the flow rate;

[0046] C is the flow coefficient, which needs to be calibrated in advance;

[0047] A is the cross-sectional area of the throttling device;

[0048] △P is the differential pressure between the upstream and downstream of the throttling device;

[0049] ρ is the density of the fluid.

[0050] It should be noted that this calculation part does not fall within the scope of protection of the present utility model and is only provided for reference.

[0051] Embodiment 3

[0052] For a 1000MW unit in China, the air and flue gas system is equipped with two induced draft fans, with a rated speed of 990 r / min. Stall phenomena often occur during high-load operation, and it is necessary to conduct on-line monitoring of its operating parameters to assist in judging the operating state of the fans.

[0053] The flow parameter monitoring adopts a differential pressure flowmeter based on a multi-point sampling measurement structure type provided by the present utility model, which is installed at the diffuser position of the induced draft fan outlet. No problems such as blockage or large data errors have occurred during the half-year operation, and good results have been achieved.

[0054] The above shows and describes the basic principles, main features and advantages of the present utility model. For those skilled in the art, it is obvious that the present utility model is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or basic features of the present utility model. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present utility model is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present utility model. Any reference signs in the claims should not be regarded as limiting the claimed rights.

[0055] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art. The above content is only to illustrate the technical idea of the present invention, and the protection scope of the present invention cannot be limited thereby. Any modification made on the basis of the technical solution according to the technical idea proposed by the present invention falls within the protection scope of the claims of the present invention.

Claims

1. A differential pressure flowmeter based on a multi-point sampling measurement structure type, characterized in that, It includes a total pressure sampler (1), a total pressure pipe (2) and a static pressure pipe (3); The total pressure sampler (1) is L-shaped. The total pressure sampler inlet (4) faces the oncoming flow direction. The total pressure pipe (2) is connected through the total pressure sampler connecting pipe (6). The back of the total pressure pipe (2) is the static pressure pipe (3), and the positions of the static pressure holes of the static pressure pipe (3) correspond one by one to the total pressure sampler connecting pipe (6).

2. The differential pressure flowmeter according to claim 1, which is based on a multi-point sampling measurement structure type, is characterized in that, The aperture R2 of the total pressure sampler (1) is not less than 10 mm.

3. The differential pressure flowmeter based on the multi-point sampling measurement structure type according to claim 2, wherein, If the dust content in the raw flue gas is lower than 30 mg / Nm during more than half of the operating time of the power plant 3 then R2 = 10 mm; otherwise, R2 = 15 mm.

4. The differential pressure flowmeter based on the multi-point sampling measurement structure type according to claim 2, characterized in that, The total pressure sampler inlet (4) faces the oncoming flow direction, where the length L1 of the oncoming flow pipe = 2R2.

5. The differential pressure flowmeter according to claim 2, characterized in that, The turning radius R1 of the total pressure sampler (1) = 1.5R2, and the length L2 of the outlet pipe section of the total pressure sampler = 1.5R2.

6. A differential pressure flowmeter based on a multi-point sampling measurement structure type according to claim 2, characterized in that, The length L3 of the total pressure sampler connecting pipe (6) = R2.

7. The differential pressure flowmeter based on the multi-point sampling measurement structure type according to claim 2, wherein The static pressure pipe (3) and the total pressure pipe (2) are arranged side by side, and the radii R3 = R4 of the static pressure pipe (3) and the total pressure pipe (2) = 1.5R2.

8. A differential pressure flowmeter based on a multi-point sampling measurement structure type according to claim 2, characterized in that, Two total pressure pipes (2) and static pressure pipes (3) in the horizontal and vertical directions are respectively arranged on the cross-section of a single flue gas pipe. The number n of total pressure samplers (1) is set according to the flue size L in each direction.

9. A differential pressure flowmeter based on a multi-point sampling measurement structure type according to claim 8, characterized in that, When the flue size L ≥ 1000 mm, the number n of total pressure samplers (1) = L / 25R2, and 3 ≤ n ≤ 8.

10. The differential pressure flowmeter based on the multi-point sampling measurement structure type according to claim 8, characterized in that, When the flue size L ≤ 1000 mm, the number n of total pressure samplers (1) = 3.

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