CS237044B1 - Sensing element for rate of flow measuring for piping with diameter less than 5mm - Google Patents

Abstract

A liquid flow sensor, especially for pipes with a diameter of less than 50 millimeters, addresses a new shape of the orifice and a new way of storing it and sealing it in the chamber. The essence of the solution consists in the fact that a screen (1) fitted with an edge shape (1a) is fitted into the shoulder (2b) of the rear body (2) and the rear body (2) is fitted with an outer cylindrical surface (2a). in the recess (3a) of the front body (3) of the chamber (4), the conical portion (2c) of the rear body (2) and the chamfer portion (3b) of the front body (3) forming a bevel for the final weld (9) and the size of the slots (8) ) entering the pulse tubes (5) in front of and behind the diaphragm (1) is defined by the length of the inflow conduit (6) embedded in the front body (3) and the outflow conduit (7) fitted into the rear body (2) welded to the chamber (4) welds (11, 12). The sensor can be used for measuring the flow of liquids through pipes, especially in nuclear power plants.

Description

(54) Sensor for measuring the flow of liquids, in particular for pipes with an inside diameter of less than 50 mm

A sensor for measuring the flow of liquids, especially for pipes with a diameter of less than 50 millimeters, solves a new shape of the orifice and a new way of its storage and sealing in the chamber bodies.

The principle of the solution consists in that in the shoulder (2b) of the rear body (2) of the chamber (4) is fitted a flap (1) with a modified shape of the edge (1a) and the rear body (2) is fitted with an outer cylindrical surface (2a). in the recess (3a) of the front body (3) of the chamber (4), wherein the conical portion (2c) of the rear body (2) and the tapered portion (3b) of the front body (3) form a bevel for the final weld (9) and slits (8) ) leading to the impulse piping (5) before and after the orifice (1) is defined by the length of the inlet piping (6) fitted in the front body (3) and the outlet piping (7) fitted in the rear body (2) welded with the chamber (4) ) welds (11, 12).

The sensor finds its application in measuring the flow of liquids through pipelines, especially in nuclear power plants.

BACKGROUND OF THE INVENTION The present invention relates to a sensor for measuring the flow of liquids, in particular for a pipe having an inside diameter of less than 50 mm, and to a novel orifice shape and a new method of its placement and sealing in chamber bodies.

The liquid flow sensors proposed and used so far are based on changing the momentum of the liquid flow, which is achieved by incorporating an orifice or nozzle into the flow line.

For the operation of nuclear power plants, a perfect sealing of all transmission channels is required by welding the elements that form the energy transmission paths. This also applies to liquid flow sensors.

Therefore, the existing sensor design is designed such that the orifice or nozzle is welded to its chamber bodies on its periphery. The resulting chamber with built-in orifice plate is then connected by two welds to the inlet and outlet piping. The legitimacy of such a design and manufacture must be compared with the requirements contained in ČSN, which must be met in order to apply the conditions for using this method of measuring the flow of liquid.

For the construction of the orifice or nozzle, the prescribed geometric similarity of the dimensions of the sensor elements applies to the orifice plate thickness E <0.05 D, the width of the cylindrical part of the orifice through hole e = 0.01 to 0.02D and the width of the <<0.03 D. Another condition for the measurement is to keep the length of the inlet pipe 50 D and the outlet pipe 10 D and the alignment of the orifice aperture with the flow pipe.

For flow ducts where the diameter D <50 millimeters is the thickness of the orifice plate Ε = 1 to 2 mm and the width of the cylindrical part of the orifice orifice e = 0.2 mm to 0.4 mm. Welding of these thin orifices with chamber bodies causes permanent deformation of the orifice disc, which results in a change of geometric shapes, failure to observe the production width of the slots of pressure signals and coaxiality of the orifice of the orifice plate with the flow line. Since the orifice with the chamber bodies forms a separate unit after welding and the inlet and outlet piping is then connected by welds, is it not possible to ensure that the prescribed straight pipe length is maintained before and after the orifice coaxial with the chamber axis? ry. These drawbacks are overcome by the liquid flow sensor according to the invention, characterized in that an aperture of a modified edge shape is fitted into the rear chamber body and the rear body is fitted with an outer cylindrical surface in the recess of the front chamber body, and the bevel portion of the front body forms a bevel for the final weld, and the size of the slots opening into the pulse ducts before and after the orifice is limited by the length of the inflow duct flush with the rear body welded to the chamber by two welds.

Advantages of the sensor according to the invention are that it complies with ČSN regulations in terms of the required accuracy of all elements. The fitting of the orifice plate by the modified shape of its edge in both newly designed chamber bodies ensures sealing of the orifice plate and execution of the final weld of both chamber bodies outside the orifice plate so that it does not deform. The fit of the inlet pipe in the front body and the outlet pipe in the rear body and their welding directly to the peripheral weld bodies ensures the width of the pressure signal slots, the alignment of the orifice cylindrical aperture with the flow pipe and coaxial with the chamber axis. Another advantage of the design of the chamber bodies is the possibility of clamping both chamber bodies with flanges with screws and nuts to verify the geometric design of the sensor. Sensor production is simpler, more accurate and more economical.

In the accompanying drawings, an exemplary embodiment of a sensor according to the invention is shown in partial cross-section, in which Fig. 1 shows the individual parts of the sensor prior to assembly; and Fig. 2 shows a composite sensor clamped by a test fixture.

The sensor consists of a front chamber 3, an orifice 1 and a rear chamber 2. The orifice 1 is formed of a circular plate and consists of a modified edge 1a, a wall 1c and a cylindrical opening 1b. The rear body 2 is formed by a rotary body with an outer cylindrical surface 2a, a conical part 2c, a shoulder 2b, an opening for the flush fit of the outlet pipe 7 and an opening for receiving the impulse piping S. The front body 3 is also formed by a rotary body with recess 3a. After welding the inlet pipe 6 and the outlet pipe 7 with the chamber bodies 4, slots 8 are formed between the pipe faces and the chamber bodies 4 leading into the impulse pipes 5 before and after aperture 1.

The aperture 1, with its adapted edge 1a, fits into the shoulder 2b of the rear body 2. The rear body 2 with the outer cylindrical part 2a fits into the recesses 3a of the front body 3.

The inlet duct 6 and the outlet duct 7 are fitted flush with the chamber bodies 4 and welded by circumferential welds 11, 12. A pulse duct 5 is inserted into the opening 3 of the front body 3 in front of the orifice 1. Then rotate the rear body 2 until the openings 3c and 2d . A pulse line 5 is inserted into the common opening of the front body 3 and the rear body 2 behind the orifice plate 1, which secures the position of the assembled parts of the sensor. The chamber 4 thus assembled is clamped by means of flanges 10 with bolts and nuts to perform a verification measurement. After evaluating the experimental results and determining the magnitude and accuracy of the flow coefficient and, in the case of favorable results, the chamber 4 is welded with a final weld 9.

The invention will find application in the measurement of fluid flow through pipelines, particularly in nuclear power plants.

Claims (2)

SUBJECT A sensor for measuring the flow of liquids, in particular for a pipe having an inside diameter of less than 50 mm, comprising an inlet and outlet pipe, orifice and a chamber with pulse pipes, characterized in that in the shoulder (2b) of the rear body (2) of the chamber (4) an aperture (1) fitted with an adapted edge shape (1aj and rear body (2J) is fitted with an outer cylindrical surface (2a) in a recess (3a) of the front body (3) of the chamber (4), the tapered portion (2c) of the rear body ( 2) and the tapered portion (3b) of the front body (3) forms a bevel for the final weld (9) and inventions the size of the slots (8) opening into the impulse ducts (5) before and after the orifice (1) is limited by the length of the inflow duct (6) fitted to the front body (3) and the drain pipe (7) fitted to the rear body (2) welded to the chamber (4) by welding (11, 12). Liquid flow sensor according to claim 1, characterized in that the opening (3c) of the front body (3) and the opening (2d) of the rear body (2) form a common opening for receiving the impulse line (5) behind the orifice (1j).