Built-in differential pressure tapping device

Abstract

The utility model belongs to the technical field of flow measurement, and particularly relates to a built-in differential pressure tapping device which comprises a shell connected in series in a pipeline to be measured, a venturi tube is arranged in the shell, a ventilation channel is reserved between the shell and the venturi tube, the venturi tube comprises a contraction section, a throat diameter section and a diffusion section which are coaxially arranged, the shell is further provided with a positive pressure tapping pipe and a negative pressure tapping pipe which are used for transmitting pressure signals, one end of the positive pressure tapping pipe is communicated with an inner cavity of the shell, the other end of the positive pressure tapping pipe is communicated with the outside of the shell, and one end of the negative pressure tapping pipe is communicated with the throat diameter section while the other end of the negative pressure tapping pipe is communicated with the outside of the shell. The utility model has the advantages of large passing area, small resistance and low requirement on the output of the fan.

Description

Technical field:

[0001] The utility model belongs to the technical field of flow measurement, in particular to a built-in differential pressure taking device. Background technology:

[0002] A burner is a device that mixes fuel and air in a specific pattern for combustion. Air is usually introduced through a blower. To ensure a consistent fuel-air mixture, the fuel and air flow rates must be monitored and adjusted.

[0003] A Chinese invention patent (publication number CN108844673A, application date 2018.06.27, publication date 2018.11.20) discloses a rectifier-type venturi tube pressure differential measuring device, wherein the measuring device is connected in series in the process pipeline to be measured; an upstream straight pipe section, an inlet cylindrical section, a venturi tube, and a downstream straight pipe section are sequentially provided in the measuring device along the direction of fluid flow; a first body flange is welded to the front end of the upstream straight pipe section, and a conical rectifier element is built into the upstream straight pipe section, the conical top end of the conical rectifier element points to the opposite direction of fluid flow, and the tail end is fixed to the inner wall of the upstream straight pipe section through a bracket; a first outer protective sleeve is nested on the outside of the inlet cylindrical section; a first annular groove is formed at the relative positions of the middle of the outer wall of the inlet cylindrical section and the middle of the inner wall of the first outer protective sleeve, and four sampling holes of equal diameter that penetrate the wall of the inlet cylindrical section are formed on the first annular groove ; The first annular groove position of the first outer protective sleeve forms a through pressure taking hole and a drain hole, and the pressure taking hole is connected to a positive pressure taking short tube for transmitting pressure signals; the Venturi tube includes a contraction section, a throat diameter section, and a diffusion section with coinciding axes; the second outer protective sleeve is nested outside the Venturi tube; a second annular groove is formed at the relative positions of the middle of the outer wall of the throat diameter section and the middle of the inner wall of the second outer protective sleeve, and four equal-diameter sampling holes that penetrate the wall of the Venturi tube are formed on the second annular groove; a through pressure taking hole and a drain hole are formed at the second annular groove position of the second outer protective sleeve, and the pressure taking hole is connected to a negative pressure taking short tube for transmitting pressure signals; the drain holes are connected to drain pipes, and the drain pipes are provided with drain valves; the tail end of the downstream straight pipe section is connected to the second body flange; the measuring device is connected to the process pipeline to be measured through the first body flange and the second body flange.

[0004] The disadvantages of the above-mentioned pressure difference measuring device are: due to the contraction of the contraction section, the throat diameter section and the diffusion section, the fluid passing area is small, the resistance is large, and the fan output requirement is high. Summary of the invention:

[0005] The utility model aims to provide a built-in differential pressure taker, which has a large passing area, small resistance and low requirements on fan output.

[0006] The utility model is achieved in this way:

[0007] A built-in differential pressure taking device includes a shell connected in series in a pipeline to be tested, a Venturi tube is provided in the shell, and a ventilation channel is left between the shell and the Venturi tube. The Venturi tube includes a coaxially arranged contraction section, a throat diameter section and a diffusion section. The shell is also provided with a positive pressure taking tube and a negative pressure taking tube for transmitting pressure signals. One end of the positive pressure taking tube is connected to the inner cavity of the shell and the other end is connected to the outside of the shell. One end of the negative pressure taking tube is connected to the throat diameter section and the other end is connected to the outside of the shell.

[0008] In the above-mentioned built-in differential pressure taker, the housing and the venturi tube are both circular tubes and are coaxially arranged.

[0009] In the above-mentioned built-in differential pressure taker, the venturi tube is installed in the housing through a mounting frame, the mounting frame includes a mounting sleeve and a connecting rod, the mounting sleeve is sleeved outside the venturi tube, and the connecting rod connects the mounting sleeve and the housing.

[0010] In the above-mentioned built-in differential pressure taker, the mounting sleeve is fixedly connected to the venturi tube by screws, one end of the connecting rod is fixedly connected to the mounting sleeve by welding, and the other end is fixedly connected to the housing by welding.

[0011] In the above-mentioned built-in differential pressure taking device, there are more than two connecting rods evenly distributed around the circumference.

[0012] In the above-mentioned built-in differential pressure taker, the shell and the venturi tube are both circular tubes, and the inner diameter of the shell is 4 to 6 times the outer diameter of the venturi tube.

[0013] In the above-mentioned built-in differential pressure taker, flanges are provided at both ends of the shell, one end of the shell is connected to the air outlet of the fan through the flange, and the other end of the shell is connected to the pipeline to be measured through the flange.

[0014] The outstanding advantages of the utility model compared with the prior art are:

[0015] 1. The utility model sets the Venturi tube in the shell, and leaves a ventilation channel between the shell and the Venturi tube, so that only part of the wind flows through the Venturi tube with large resistance, and the other part of the wind flows through the ventilation channel with small resistance. The overall flow area is large, the resistance is small, and the output requirement of the fan is low. The utility model directly connects the shell in series with the pipeline to be tested, without digging holes in the pipeline to be tested, which is convenient for processing and installation.

[0016] 2. The venturi tube of the present invention is installed in the housing through a mounting frame. The mounting frame includes a mounting sleeve and a connecting rod. The mounting sleeve is sleeved outside the venturi tube, and the connecting rod connects the mounting sleeve and the housing. The structure is simple, easy to install, and the area of the ventilation channel is ensured as much as possible.

[0017] 3. The shell and the venturi tube of the utility model are both circular tubes. The inner diameter of the shell is 4 to 6 times the outer diameter of the venturi tube, and the resistance is small. Description of the drawings:

[0018] Figure 1 It is a three-dimensional diagram of the utility model without a positive pressure-taking tube;

[0019] Figure 2 It is a cross-sectional view of the present utility model.

[0020] Figure numerals: 1. outer shell; 2. Venturi tube; 21. contraction section; 22. throat diameter section; 23. diffusion section; 3. ventilation channel; 4. positive pressure pipe; 5. negative pressure pipe; 6. mounting frame; 61. mounting sleeve; 62. connecting rod; 7. flange. Specific implementation method:

[0021] The present invention is further described below with reference to specific embodiments. Figure 1 —2:

[0022] A built-in differential pressure device includes a shell 1 connected in series in a pipe to be measured, a Venturi tube 2 is provided in the shell 1, and a ventilation channel 3 is left between the shell 1 and the Venturi tube 2. The Venturi tube 2 includes a coaxially arranged contraction section 21, a throat diameter section 22 and a diffusion section 23. The shell 1 is also provided with a positive pressure tube 4 and a negative pressure tube 5 for transmitting pressure signals. One end of the positive pressure tube 4 is connected to the inner cavity of the shell 1 and the other end is connected to the outside of the shell 1. One end of the negative pressure tube 5 is connected to the throat diameter section 22 and the other end is connected to the outside of the shell 1.

[0023] The working principle of this utility model is as follows: Figure 1 、 2 As shown, air entering from one end of housing 1 partially flows through ventilation duct 3 and out the other end, while the remaining portion flows through Venturi tube 2 and out the other end. Measuring the pressure in positive pressure pipe 4 measures the pressure inside housing 1; measuring the pressure in negative pressure pipe 5 measures the pressure in throat diameter section 22. Given the cross-sectional area and pressure differential, the flow rate can be calculated based on the flow continuity equation (law of conservation of mass) and Bernoulli's equation (law of conservation of energy).

[0024] The utility model arranges the venturi tube 2 in the shell 1, and leaves a ventilation channel 3 between the shell 1 and the venturi tube 2, so that only a part of the wind flows through the venturi tube 2 with large resistance, and the other part of the wind flows through the ventilation channel 3 with small resistance. The overall passing area is large, the resistance is small, and the output requirement of the fan is low. The utility model directly connects the shell 1 in series to the pipeline to be measured, and there is no need to dig a hole in the pipeline to be measured, which is convenient for processing and installation.

[0025] In order to discharge air evenly, the housing 1 and the venturi tube 2 are both circular tubes and are coaxially arranged.

[0026] The installation structure of the venturi tube 2: Figure 1 As shown, the venturi tube 2 is mounted within the housing 1 via a mounting bracket 6. The mounting bracket 6 includes a mounting sleeve 61 and a connecting rod 62. The mounting sleeve 61 is mounted on the outside of the venturi tube 2, and the connecting rod 62 connects the mounting sleeve 61 and the housing 1. This structure is simple, easy to install, and the area of the ventilation channel 3 is maximized.

[0027] The mounting structure of the mounting frame 6: the mounting sleeve 61 is fixedly connected to the venturi tube 2 by screws, and one end of the connecting rod 62 is fixedly connected to the mounting sleeve 61 by welding, and the other end is fixedly connected to the housing 1 by welding.

[0028] In order to better fix the venturi tube 2, there are more than two connecting rods 62 evenly distributed around the circumference. In this embodiment, there are three connecting rods 62 evenly distributed around the circumference.

[0029] To reduce air flow resistance, the housing 1 and the venturi tube 2 are both circular tubes, and the inner diameter of the housing 1 is 4 to 6 times the outer diameter of the venturi tube 2. In this embodiment, the inner diameter of the housing 1 is 250 mm, and the outer diameter of the venturi tube 2 is 52 mm, so the inner diameter of the housing 1 is 4.8 times the outer diameter of the venturi tube 2.

[0030] In this embodiment, the actual wind passing area is more than 80% of the area of the entire housing 1, and the resistance is very small.

[0031] Installation structure of the housing 1: Flanges 7 are provided at both ends of the housing 1. One end of the housing 1 is connected to the air outlet of the fan through the flange 7, and the other end is connected to the pipeline to be tested through the flange 7.

[0032] The above embodiment is only one of the preferred embodiments of the present invention and is not intended to limit the scope of implementation of the present invention. Therefore, any equivalent changes made based on the shape, structure, and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A built-in differential pressure sensor, characterized by: The invention comprises a housing (1) connected in series in a pipe to be measured, a venturi tube (2) is provided in the housing (1), a ventilation channel (3) is left between the housing (1) and the venturi tube (2), the venturi tube (2) comprises a coaxially arranged contraction section (21), a throat diameter section (22) and a diffusion section (23), the housing (1) is further provided with a positive pressure-taking tube (4) and a negative pressure-taking tube (5) for transmitting a pressure signal, one end of the positive pressure-taking tube (4) is connected to the inner cavity of the housing (1) and the other end is connected to the outside of the housing (1), the one end of the negative pressure-taking tube (5) is connected to the throat diameter section (22) and the other end is connected to the outside of the housing (1), the The housing (1) and the venturi tube (2) are both circular tubes. The inner diameter of the housing (1) is 4 to 6 times the outer diameter of the venturi tube (2). The venturi tube (2) is installed in the housing (1) via a mounting frame (6). The mounting frame (6) comprises a mounting sleeve (61) and a connecting rod (62). The mounting sleeve (61) is sleeved outside the venturi tube (2). The connecting rod (62) connects the mounting sleeve (61) and the housing (1). The mounting sleeve (61) is fixedly connected to the venturi tube (2) via screws. One end of the connecting rod (62) is fixedly connected to the mounting sleeve (61) via welding, and the other end is fixedly connected to the housing (1) via welding.

2. The built-in differential pressure device according to claim 1, characterized in that: The housing (1) and the venturi tube (2) are both circular tubes and are coaxially arranged.

3. The built-in differential pressure device according to claim 1, characterized in that: Flanges (7) are respectively provided at both ends of the housing (1); one end of the housing (1) is connected to the air outlet of the fan via the flange (7), and the other end is connected to the pipeline to be tested via the flange (7).

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