RU2208767C2 - Pressure transducer for flowmeter - Google Patents

Abstract

FIELD: instrumentation engineering. SUBSTANCE: proposed expansion-type pressure transducer is designed for measuring rates of single-phase and multiple-phase flows of liquid media in pipelines of different application with diameter from 10 to 2500 mm. Diffuser-contraction channel of pressure transducer is formed by diffuser insert and contraction insert placed inside cylindrical housing between inlet and outlet branch pipes, said insert being butt joined in maximum section. Inlet branch pipe is furnished with flange hermetically screwed into housing. Outlet branch pipe is provided with flange hermetically connected with housing. EFFECT: enlarged functional capabilities of device. 5 cl, 6 dwg

Description

 The invention relates to measuring equipment and can be used to measure the flow of liquid, gas and steam in pressure pipelines.

 Typically, pressure sensors for expansion type flowmeters comprise a diffuser-confuser type measuring channel with a maximum cross section that is greater than the total cross section of the pipeline in which the flow meter is installed. Due to this, high measurement accuracy is achieved at small pressure drops, therefore, the associated energy loss is reduced; reliability increases due to the absence of abrasive wear in flow conditions with solid or abrasive particles; there is no risk of cavitation in liquids; there is a small likelihood of clogging of the pressure sampling holes in suspended fluid. In addition, an important advantage of expansion type flowmeters is that the measurement error can be determined in them by calculation without laborious and expensive bench tests, and their periodic calibration is carried out by instrumental measurements of the geometric parameters of the measuring channel, such as the diameters of the inlet and outlet nozzles with full transverse sections and the diameter of the maximum section.

 The pressure sensor for the expanding type flowmeter [1], selected as a prototype, is made in the form of a body built into the pipeline containing a cylindrical inlet pipe with a normal cross section, a housing inside which a diffuser-confuser channel with a maximum cross section is made, and a cylinder outlet pipe with normal cross section. In normal sections of the inlet and outlet nozzles, as well as in the maximum section of the housing, holes for pressure selection are made, surrounded by averaging collectors, to which secondary devices are connected, for example, via fittings.

 To protect the measuring channel from mechanical damage by fluid streams with large and solid inclusions, a cylindrical safety insert is provided that passes a fluid stream without inclusions to the pressure sampling holes. The known sensor for a flowmeter of an expanding type has all the advantages described above inherent in devices of this type, as well as such an additional advantage as the ability to measure the flow rate of contaminated fluids with high accuracy. However, in the known device, calibration of the measuring channel, especially its maximum cross section, is difficult. In addition, the manufacturing process of the diffuser-confuser case is very time-consuming. The operating costs are also large and the service life of the flowmeter assembly is small, for example, in conditions of intensive wear of the internal surfaces of the measuring channel. All this taken together constitutes the disadvantages of the known prototype design.

 The aim of the present invention is to eliminate the above-mentioned disadvantages of the known design of the prototype.

 According to the invention, the goal is achieved due to the fact that the pressure sensor for the flow meter is made in the form of a tubular body embedded in the pipeline containing a cylindrical inlet pipe with a transverse normal section, a housing with a diffuser-confuser channel with a transverse maximum section and a cylindrical outlet pipe with a transverse normal section, moreover, in normal sections of the inlet and outlet nozzles and in the maximum section of the housing, holes for pressure selection are made, surrounded by manifolds configured to attach secondary devices to them, characterized in that the diffuser-confuser channel is formed by a diffuser-liner and a confuser-liner arranged inside the cylindrical body between the inlet and outlet nozzles, joined in the maximum section, and the inlet nozzle is tightly screwed into the housing is a flange, and the outlet pipe is provided with a rigidly fixed flange sealed to the housing.

The invention is illustrated in detail by drawings, on which:
figure 1 - pressure sensor, side view, half section;
figure 2 is a section along the line (1-1) in figure 1;
figure 3 is a section along the line (2-2) in figure 1;
figure 4 is a section along the line (3-3) in figure 1;
5 is a section along the line (4-4) in figure 1;
6 is a section along the line (5-5) in figure 1.

 The flow of fluid moves in an arrow from left to right.

 The pressure sensor for the flow meter is made in the form of a tubular body embedded in the pipeline and contains an inlet pipe (1) with a transverse normal section (2), a housing (3) with a diffuser-confuser channel (4) having a maximum cross section (5), an outlet pipe (6) with a transverse normal section (7). In the normal section (2), holes (8) for pressure collection are made, surrounded by averaging manifold (9), in the maximum section (5) holes (10) for pressure collection are made, surrounded by averaging collector (11), and finally, in a normal section (7) openings (12) for pressure removal are made, surrounded by an averaging collector (13). The diffuser-confuser channel (4) is formed by the diffuser insert (14) and the confuser insert (15), joined in the maximum section (5). The inlet pipe (1) is provided with a flange (16) tightly screwed into the body (3), and the outlet pipe (6) is equipped with a rigidly mounted flange (17), hermetically connected to the body (3), for example, by means of a weld.

 The channels of the averaging collectors (9) and (13) are L-shaped. In this case, the averaging collector (9) is located between the end (18) and outer (19) surfaces of the diffuser insert on one side and the inner wall (20) of the flange (16) and the inner wall (21) of the housing (3) on the opposite side. The averaging collector (13) is located between the end (36) and the outer (37) surfaces of the confuser insert on one side and the inner wall (38) of the flange (17) and the inner wall (21) of the housing (3) on the opposite side. The averaging collector channel (11) is made in the form of a concentric ring and is located symmetrically with respect to the junction of the diffuser insert and the confuser insert in the maximum section.

The diffuser insert (14) and the confuser insert (15) are joined from the condition: L _D ≥L _K ; α _D ≤α _K , where L _D and α _D are the axial length and diffuser angle of the diffuser insert, respectively; L _K and α _K are the axial length and confuser angle of the confuser insert, respectively.

 In order to avoid fluid flow in the landing planes (22) and (23), respectively, of the diffuser insert (14) and the confuser insert (15), as well as in the corresponding planes of their contacts (24) and (25) with the inner surface (21) housing (3) are located sealing elements (26).

 For more reliable fixation in the given dimensions, the diffuser insert (14) and the confuser insert (15) are made with the corresponding ledges (27) and (28) abutting against the inner end surfaces, respectively (29) and (30), flush with the inner walls ( 31) and (32) of the inlet (1) and outlet (6) pipes, respectively.

 Averaging collectors (9), (11) and (13) are connected to the corresponding holes (33), (34) and (35) made in the housing (3) for connecting secondary indicating or recording instruments such as differential pressure gauges or secondary electronic calculating devices .

The principle of operation of the described pressure sensor is as follows. The fluid flow passes through the inlet pipe (1), where the pressure (P ₁ ) is recorded, the diffuser-confuser channel (4), in the maximum cross-section (5) of which the maximum pressure (P ₂ )> (P ₁ ) is recorded, and then passes outlet pipe (6), where pressure (P ₃ ) <(P ₂ ) is recorded. Then, by the values of the pressure drops (P ₂ -P ₁ ) or (P ₂ -P ₃ ), the flow rate of the fluid is determined, and the pressure drop (P ₁ -P ₂ ) determines the pressure loss in the sensor. When periodic calibrations of the pressure sensor are carried out using instrumental methods, the inlet flange (1) is screwed up and the diffuser insert (14) and the confuser insert (15) are sequentially pulled out and all their geometric parameters are measured. If, according to the results of verification, a mismatch between the geometric characteristics of the measuring channel and the requirements of the standard is revealed, for example, due to wear on the internal surfaces, then only worn out liners can be replaced with new ones without any difficulty. This reduces operating costs and increases the life of the flowmeter assembly as a whole.

The proposed pressure sensor can be used in pressure pipelines for various purposes with a diameter of 10 to 2500 mm for measuring the flow rate of both single-phase and multiphase fluid flows. Especially promising is the use of the sensor in gas-hydraulic systems for commercial metering of the flow of liquid, gas or steam, as well as in systems with suspended or contaminated fluid flows. Among the possible areas of use of the pressure sensor are the following:
- water supply and sanitation of populated areas and industrial enterprises;
- chemical and petrochemical industry;
- hydrotransport systems for mortars and mixtures;
- gas-hydraulic systems in the energy sector;
- gas-hydraulic technologies in the food industry and agriculture.

Claims (5)

 1. The pressure sensor for the flow meter, made in the form of a tubular body embedded in the pipeline, containing cylindrical inlet and outlet nozzles and a housing with a diffuser-confuser channel with a transverse maximum section, and holes for selection are made in the sections of the inlet and outlet nozzles and in the maximum section of the housing pressure surrounded by averaging collectors with holes for measuring the differential pressure by secondary devices, characterized in that the diffuser-confuser channel is formed placed internally When the cylindrical body between the inlet and outlet cone and a liner insert-confuser, docked in the maximum-section, the inlet is provided with a flange is screwed into the housing, and the outlet is provided with a sealingly connected to the housing flange.  2. The pressure sensor for the flow meter according to claim 1, characterized in that the channels of the averaging collectors of the input and output nozzles are L-shaped and are located between the end and outer surfaces of the diffuser insert and the confuser insert, on the one hand, and the inner walls of the flanges and the case on the opposite side, and the channel of the averaging collector in the maximum section is made in the form of a concentric ring and is located symmetrically relative to the junction of the insert-diffuser and the insert-confuser in the maximum section. 3. The pressure sensor for the flow meter according to claim 1, characterized in that the coupling of the diffuser insert and the confuser insert is made from the condition L _D ≥L _K ; α _D ≤α _K , where L _D and α _D are the axial length and diffuser angle of the diffuser insert, respectively; L _K and α _K are the axial length and confuser angle of the confuser insert, respectively.  4. The pressure sensor for the flow meter according to claim 1, characterized in that in the planes of landing of the liner-diffuser and liner-confuser, as well as in the planes of their contacts with the inner generatrix of the housing are sealing elements.  5. The pressure sensor for the flow meter according to claim 1, characterized in that the diffuser insert and the confuser insert are made with ledges abutting against the inner end surfaces of the inlet and outlet pipes, respectively, flush with their inner walls.

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