Limiting orifice plate for backflow pipeline of nuclear power plant

Abstract

The utility model discloses a flow-limiting orifice plate for a backflow pipeline of a nuclear power plant, relates to the technical field of transportation of fluid in a pipeline, and is used for solving the problems of violent vibration and noise of the pipeline caused by cavitation of an existing flow-limiting orifice plate for a pipeline of a safety facility system. The restriction orifice plate comprises an orifice plate and a handle arranged above the orifice plate, the pore plate is round, the thickness of the pore plate is 1 / 10-1 / 4 of the inner diameter of the pipeline where the pore plate is located, a round hole is formed in the middle of the pore plate, and a chamfer is arranged on one side of the round hole; the size of the chamfer is 1 / 2-2 / 3 of the thickness of the pore plate; and the flow-limiting orifice plate is mounted in the pipeline through an ASME standard flange. The flow state behind the pore plate can be improved by adopting the oblique-angle flow limiting pore plate, the pipe nozzle jet flow of the right-angle pore plate is changed into orifice diffusion flow, the lowest pressure P2 behind the pore plate can be further increased, the cavitation phenomenon behind the pore plate is weakened, and the cavitation performance of the pore plate is improved.

Description

Technical Field

[0001] This utility model patent belongs to the field of pipeline fluid transportation technology, specifically relating to a flow-limiting orifice plate for a nuclear power plant return pipeline. Background Technology

[0002] Nuclear power plants typically have dedicated safety systems with reflux lines. During periodic system testing or major overhauls, the system and equipment functionality is tested and verified by opening the reflux line shut-off valve. To ensure the safety of the system and equipment during testing, flow-limiting orifice plates are usually installed on the reflux line to reduce pressure and limit flow.

[0003] Currently, the system's return pipeline is typically equipped with a single-stage circular orifice plate. When the liquid flows through the orifice, the velocity increases and the pressure decreases. At a certain position after the orifice, the pressure drops to a minimum pressure P2. When the minimum pressure P2 is less than the local saturated vapor pressure P... v At this time, cavitation will occur after the orifice plate. As the downstream liquid pressure rises, the vaporized bubbles will collapse under the action of the downstream liquid pressure, generating micro-jet with instantaneous pressure of tens or hundreds of megapascals. The micro-jet will hit the pipe wall, causing serious vibration and noise problems, which will endanger the safe operation of the system. Utility Model Content

[0004] The purpose of this utility model is to provide a flow-limiting orifice plate for nuclear power plant return pipelines, which solves the problem of severe pipeline vibration and noise caused by cavitation of existing safety facility system pipeline flow-limiting orifice plates, reduces or eliminates the cavitation phenomenon of the orifice plate, and reduces vibration and noise problems during system operation.

[0005] The technical solution adopted by this utility model to solve its technical problem is: a flow-limiting orifice plate for a nuclear power plant return pipeline, including an orifice plate and a handle disposed above the orifice plate; the orifice plate is circular, and the thickness of the orifice plate is between 1 / 10 and 1 / 4 of the inner diameter of the pipeline in which it is located, with a circular hole in the middle, and a chamfer on one side of the circular hole; the size of the chamfer is between 1 / 2 and 2 / 3 of the thickness of the orifice plate; the flow-limiting orifice plate is installed in the pipeline through an ASME standard flange.

[0006] The above-mentioned flow-limiting orifice plate for a nuclear power plant return pipeline is wherein the orifice plate and the handle are connected by welding, and both are typically made of carbon steel or stainless steel.

[0007] The above-mentioned flow-limiting orifice plate for a nuclear power plant return pipeline has a chamfer on the outflow side of the liquid in the pipeline, and the orifice diameter on the inflow side is smaller than the orifice diameter on the outflow side.

[0008] The above-mentioned flow-limiting orifice plate for a nuclear power plant return pipeline has sharp edges on both sides of the orifice diameter.

[0009] The above-mentioned flow-limiting orifice plate for a nuclear power plant return pipeline is installed between two symmetrical ASME standard flanges, and is fixed by studs passing through the through holes on the upper and lower parts of the ASME standard flanges, and then by nuts and washers.

[0010] The above-mentioned flow-limiting orifice plate for a nuclear power plant return pipeline is wherein the flow-limiting orifice plate and the ASME standard flange are sealed with a gasket.

[0011] The above-mentioned flow-limiting orifice plate for a nuclear power plant return pipeline is wherein the ASME standard flange on which the flow-limiting orifice plate is installed is welded in the pipeline. When the flow-limiting orifice plate needs to be replaced, it is replaced by removing the studs.

[0012] Compared with the prior art, the beneficial effects of this utility model are: the flow limiting orifice plate for nuclear power plant return pipeline provided by this utility model adopts an angled flow limiting orifice plate, which can improve the flow state after the orifice plate. It changes the jet flow of the nozzle of the right angle orifice plate to the diffusion flow of the orifice, which can further increase the minimum pressure P2, reduce the cavitation phenomenon after the orifice plate, and improve the cavitation performance of the orifice plate. Attached Figure Description

[0013] Figure 1 The image shown is a front view of a flow-limiting orifice plate for a nuclear power plant return pipeline according to the present invention.

[0014] Figure 2 The image shown is a side view of a flow-limiting orifice plate for a nuclear power plant return pipeline according to the present invention.

[0015] Figure 3 The diagram shows the installation of a flow-limiting orifice plate for a nuclear power plant return pipeline according to the present invention.

[0016] The following are the labels in the attached diagram: 1. Handle; 2. Orifice plate; 3. ASME standard flange; 4. Flow restrictor plate; 5. Sealing gasket; 6. Nut; 7. Washer; 8. Stud. Detailed Implementation

[0017] To address the severe vibration and noise issues caused by cavitation in existing safety facility systems' orifice plates, this utility model provides an orifice plate for nuclear power plant return pipelines. For example... Figures 1-3 As shown, the flow-limiting orifice plate 4 includes: an orifice plate 2 and a handle 1 disposed above the orifice plate; the orifice plate 2 and the handle 1 are connected by welding to facilitate the installation and disassembly of the flow-limiting orifice plate 4. Both are typically made of carbon steel or stainless steel. The handle 1 is usually a thin sheet structure, formed by stamping, while the orifice plate 2 is a rotating structure, usually machined.

[0018] Orifice plate 2 is circular, and its thickness is between 1 / 10 and 1 / 4 of the inner diameter of the pipe it is in. It has a circular hole in the center, and one side of the hole has a chamfer; the size of the chamfer is between 1 / 2 and 2 / 3 of the thickness of orifice plate 2. Flow-limiting orifice plate 4 is installed in the pipe via an ASME standard flange 3. The chamfer of flow-limiting orifice plate 4 is located on the outflow side of the liquid in the pipe, and the orifice diameter on the inflow side is smaller than that on the outflow side. Both sides of the orifice diameter of flow-limiting orifice plate 4 retain sharp edges, and burrs should be removed after the entire orifice plate is machined.

[0019] The flow-limiting orifice plate 4 is installed between two symmetrical ASME standard flanges 3, and the two are sealed with a gasket 5. The studs 8 are passed through the through holes at the top and bottom of the ASME standard flanges 3, and then the studs 8 are tightened at both ends with nuts 6 and washers 7.

[0020] The ASME standard flange 3 for installing the flow restrictor 4 is welded into the pipeline. When the flow restrictor 4 needs to be replaced, it is replaced by removing the stud 8.

[0021] It should be noted that the combination of the technical features in the embodiments of this utility model is not limited to the combination methods recorded in the embodiments of this utility model or the combination methods recorded in specific embodiments. All technical features recorded in this utility model can be freely combined or combined in any way, unless there is a contradiction between them.

[0022] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications or equivalent substitutions made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A flow-limiting orifice plate for a nuclear power plant return pipeline, characterized in that, The flow-limiting orifice plate (4) includes: an orifice plate (2) and a handle (1) disposed above the orifice plate; the orifice plate (2) is circular, and the thickness of the orifice plate (2) is between 1 / 10 and 1 / 4 of the inner diameter of the pipe in which it is located. A circular hole is provided in the middle, and a chamfer is provided on one side of the circular hole; the size of the chamfer is between 1 / 2 and 2 / 3 of the thickness of the orifice plate (2); the flow-limiting orifice plate (4) is installed in the pipe through an ASME standard flange (3).

2. The flow-limiting orifice plate for a nuclear power plant return pipeline according to claim 1, characterized in that, The orifice plate (2) and the handle (1) are connected by welding, and both are usually made of carbon steel or stainless steel.

3. The flow-limiting orifice plate for a nuclear power plant return pipeline according to claim 1, characterized in that, The chamfer of the flow-limiting orifice plate (4) is set on the outflow side of the liquid in the pipe, and the orifice diameter on the inflow side is smaller than that on the outflow side.

4. A flow-limiting orifice plate for a nuclear power plant return pipeline according to claim 1, characterized in that, The flow-limiting orifice plate (4) has sharp edges on both sides of its aperture.

5. A flow-limiting orifice plate for a nuclear power plant return pipeline according to claim 1, characterized in that, The flow-limiting orifice plate (4) is installed between two symmetrical ASME standard flanges (3), and is fixed by studs (8) passing through the through holes on the upper and lower parts of the ASME standard flanges (3) and nuts (6) and washers (7).

6. A flow-limiting orifice plate for a nuclear power plant return pipeline according to claim 5, characterized in that, The flow-limiting orifice plate (4) and the ASME standard flange (3) are sealed with a gasket (5).

7. A flow-limiting orifice plate for a nuclear power plant return pipeline according to claim 1, characterized in that, The ASME standard flange (3) for installing the flow restrictor plate (4) is welded in the pipeline. When the flow restrictor plate (4) needs to be replaced, it is replaced by removing the stud (8).

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