Method of flushing and flushing system for mechanical seals

Abstract

The present application relates to the technical field of fluid machinery seal, and provides a flushing method and a flushing system for mechanical seal, the flushing method comprising: circulating the spacer fluid in the spacer fluid circulation loop to flush the mechanical seal; making the cooling fluid flow through the heat exchange mechanism to exchange heat with the spacer fluid; connecting the cooling fluid source to the spacer fluid circulation loop through the pressure compensation pipeline, and providing a one-way valve on the pressure compensation pipeline, so that the cooling fluid is one-way supplemented into the spacer fluid circulation loop through the one-way valve when the pressure is lower than the preset pressure, and the one-way valve prevents the spacer fluid from flowing reversely into the cooling fluid source; and making the cooling fluid flow through the cooling fluid circuit provided with a flow indicator and a resistance element, observing the flow state through the flow indicator, and detecting the seal leakage based on the inlet and outlet flow difference, so that the closed circulation of the spacer fluid is realized, the inlet and outlet flow difference is directly displayed through the flow indicator, and the instant visual monitoring of the internal leakage of the mechanical seal is realized.

Description

Technical Field

[0001] This invention relates to the field of fluid mechanical seal technology, and more specifically to a flushing method and flushing system for mechanical seals. Background Technology

[0002] In fluid transport equipment such as chemical pumps, the reliability of mechanical seals is crucial. The PLAN54 scheme in the API 682 standard is a commonly used pressurized double-end face seal flushing scheme. It uses an external cleaning fluid (isolation fluid) to enter the sealing cavity for flushing and cooling, and the pressure of the isolation fluid is higher than the pressure of the sealed medium to prevent the leakage of harmful media.

[0003] However, existing PLAN54 solutions typically employ an open-loop system, where the isolation fluid (usually clean water) is directly discharged as wastewater after passing through the mechanical seal, resulting in significant waste of clean water and increased wastewater treatment costs. Furthermore, when internal leakage occurs in the mechanical seal (i.e., the isolation fluid leaks into the process medium), the process medium does not leak out because the isolation fluid pressure is higher than the medium pressure. This leads to no significant change in external system pressure and level, making it difficult for operators to detect the fault promptly using conventional instruments. The problem is often only discovered when the downstream process medium is diluted or contaminated, by which time substantial production losses have often already occurred. Therefore, how to achieve the recycling of flushing water and how to promptly detect internal leakage in mechanical seals are pressing technical problems that need to be solved. Summary of the Invention

[0004] To address the problems of high flushing fluid consumption, inability to recycle, and difficulty in timely detection of internal leakage in mechanical seals in existing technologies, this application proposes a flushing method and system for mechanical seals. By utilizing a cooling fluid circuit, it simultaneously achieves cooling of the isolation fluid, system pressurization, and visual monitoring of leakage, realizing closed-loop recycling of the flushing fluid and significantly improving the timeliness of fault detection.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A flushing method for a mechanical seal includes: circulating a release fluid in a release fluid circulation loop to flush the mechanical seal; allowing a cooling fluid to flow through a heat exchange mechanism to exchange heat between the release fluid and the cooling fluid; when the pressure of the release fluid circulation loop is lower than a preset pressure, the cooling fluid is unidirectionally replenished into the release fluid circulation loop via a one-way valve on the cooling fluid loop, the one-way valve preventing the release fluid from flowing back out; and allowing the cooling fluid to flow through the cooling fluid loop, the cooling fluid loop being provided with a flow indicator, through which the flow state of the cooling fluid is observed to detect seal leakage based on the flow difference between the inlet and outlet of the cooling fluid loop.

[0006] In the above scheme, the isolation fluid is circulated in a closed loop and exchanges heat with the cooling fluid through a heat exchange mechanism, thus achieving circulating cooling of the isolation fluid and avoiding waste from discharge. One-way pressure replenishment is achieved by setting a check valve on the cooling fluid loop. When the isolation fluid system pressure is insufficient, cooling fluid is automatically added to maintain positive pressure and effectively prevents backflow of the isolation fluid. By setting flow indicators at the inlet and outlet of the cooling fluid loop, the difference in inlet and outlet flow rates caused by the increase in cooling fluid replenishment when the seal leaks is realized, enabling visual monitoring of the leak.

[0007] Preferably, the flow indicator includes a first indicator disposed on the cooling fluid inlet pipe and a second indicator disposed on the cooling fluid outlet pipe.

[0008] By installing indicators at the inlet and outlet, operators can visually compare the differences in inflow and outflow to determine if a leak exists.

[0009] Preferably, the flow indicator is a flow sight glass.

[0010] The flow sight glass has a simple structure and low cost, and can intuitively display the fluid flow state and velocity changes.

[0011] Preferably, the one-way valve is disposed on the cooling fluid circuit, and the outlet of the one-way valve is connected to the gas phase space of the isolation liquid container.

[0012] By introducing the outlet of the check valve into the gas phase space, it is ensured that the outlet of the check valve never comes into contact with the isolation fluid, forming a physical barrier and eliminating the risk of backflow of the isolation fluid.

[0013] Furthermore, the present invention also provides a mechanical seal flushing system, comprising: a sealing cavity configured to accommodate a mechanical seal assembly; a separating fluid container configured to accommodate a separating fluid, the separating fluid container being in communication with the sealing cavity; a heat exchange mechanism configured to allow the separating fluid to exchange heat with a cooling fluid; a one-way valve disposed on a cooling fluid circuit, the outlet end of the one-way valve being connected to the gas phase space of the separating fluid container; and a cooling fluid circuit including a cooling fluid inlet pipe and a cooling fluid outlet pipe, wherein flow indicators are respectively provided on the cooling fluid inlet pipe and the cooling fluid outlet pipe.

[0014] In the above system, the components are connected by pipelines to form a complete flushing system. The sealed cavity is connected to the isolation fluid container to form a closed circulation loop of the isolation fluid. The heat exchange mechanism realizes the heat exchange between the isolation fluid and the cooling fluid. The one-way valve automatically replenishes the cooling fluid to maintain positive pressure and prevent backflow when the isolation fluid system pressure is insufficient. The flow indicator on the cooling fluid loop realizes the visual monitoring of leakage.

[0015] Preferably, the one-way valve is disposed at the top of the isolation liquid container, and the outlet end of the one-way valve extends into the gas phase space of the isolation liquid container.

[0016] This structure ensures that the outlet of the one-way valve is always in the gas phase, and even if the level of the isolation fluid fluctuates, it can absolutely prevent the isolation fluid from flowing back into the cooling fluid system, thus ensuring the safety of the system.

[0017] Preferably, the one-way valve is a constant pressure one-way valve, which is configured to open automatically when the pressure of the isolation liquid container is lower than a preset pressure.

[0018] The constant pressure check valve can automatically maintain the system pressure stability without manual intervention, thus improving the system's automation level.

[0019] Preferably, the heat exchange mechanism is a coil heat exchanger disposed in the isolation liquid container, and the cooling fluid flows within the coil heat exchanger.

[0020] Integrating the heat exchanger inside the container reduces external piping connections, making the system structure more compact and reducing potential leak points. Beneficial effects

[0021] The technical solution provided by this invention has the following beneficial effects: 1. It achieves closed-loop recycling of the isolation fluid, removes heat through the heat exchange mechanism, avoids direct discharge of clean water, significantly saves water resources and sewage treatment costs, and meets energy conservation and environmental protection requirements.

[0022] 2. Real-time visual monitoring of internal leakage of mechanical seals is realized. By setting flow indicators at the inlet and outlet of the cooling fluid circuit, when the seal fails, a large amount of cooling fluid is replenished through the check valve, causing an imbalance in the inlet and outlet flow. Operators can visually detect the abnormality through the flow sight glass, avoiding the expansion of the fault and the contamination of the process medium.

[0023] 3. The system has high safety. By setting the outlet of the one-way valve in the gas phase space, the risk of backflow of the isolation liquid into the cooling water system is completely eliminated, and the cross-contamination hazards when multiple pumps share the flushing source in the existing technology are solved.

[0024] 4. The structure is compact and utilizes the cooling fluid circuit to simultaneously achieve the triple functions of heat exchange, pressure replenishment and leakage indication, realizing the "one source, three uses" of cooling fluid, reducing system complexity and manufacturing costs. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the mechanical seal flushing system according to an embodiment of the present invention.

[0026] Among them, 1-sealed cavity, 2-isolation fluid container, 3-heat exchange mechanism, 4-pressure replenishment pipeline, 5-one-way valve, 6-cooling fluid inlet pipeline, 7-cooling fluid outlet pipeline, and 8-flow indicator. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0029] like Figure 1 As shown, this embodiment provides a flushing method for a mechanical seal and a flushing system for implementing the method.

[0030] First, the operation process of the flushing method is explained. During operation, the isolation fluid circulates in the isolation fluid circulation loop to flush the mechanical seal. Simultaneously, cooling fluid flows through the heat exchange mechanism 3, allowing heat exchange between the isolation fluid and the cooling fluid, carrying away the frictional heat from the mechanical seal and the heat conducted by the process medium absorbed by the isolation fluid during circulation. When the pressure in the isolation fluid circulation loop is lower than the preset pressure, cooling fluid is replenished into the isolation fluid circulation loop through the one-way valve 5 on the cooling fluid loop, preventing the isolation fluid from flowing back out. The cooling fluid flows through the cooling fluid loop, which is equipped with a flow indicator 8. The flow state of the cooling fluid is observed through the flow indicator 8 to detect seal leakage based on the flow difference between the inlet and outlet of the cooling fluid loop.

[0031] The specific structure of the flushing system for implementing the above flushing method is described below. The flushing system mainly includes a sealed cavity 1, an isolation liquid container 2, a heat exchange mechanism 3, a one-way valve 5, and a cooling fluid circuit.

[0032] Sealing chamber 1 is configured to house the mechanical seal assembly, and its interior is filled with a release fluid for sealing and lubricating the pump shaft. Release fluid container 2 is configured to hold the release fluid and is connected to sealing chamber 1 via a pipeline, forming a closed-loop circulation loop for the release fluid. Unlike the direct discharge of the release fluid in the existing PLAN54 scheme, the release fluid in this embodiment is circulated within the system, significantly saving water resources and reducing wastewater treatment costs. Heat exchange mechanism 3 is configured to facilitate heat exchange between the release fluid and the cooling fluid, ensuring stable viscosity and lubrication performance of the release fluid.

[0033] A one-way valve 5 is installed in the cooling fluid circuit to replenish the cooling fluid in the isolation fluid container 2 when the pressure of the isolation fluid system is insufficient, thereby maintaining the positive pressure state of the isolation fluid system. The outlet end of the one-way valve 5 is connected to the gas phase space of the isolation fluid container 2. In this embodiment, the "gas phase space" refers to the gas space located above the liquid surface of the isolation fluid inside the isolation fluid container 2. By placing the outlet end of the one-way valve 5 in the gas phase space, regardless of the fluctuation of the liquid level in the isolation fluid container 2, the outlet of the one-way valve 5 never comes into contact with the isolation fluid, thus forming a physical barrier. This completely eliminates the risk of backflow of the isolation fluid through the one-way valve 5 when the pressure is abnormal, and solves the potential cross-contamination hazard when multiple pumps share a flushing source.

[0034] Furthermore, a one-way valve 5 is positioned at the top of the isolation liquid container 2, with its outlet extending into the gas phase space of the isolation liquid container 2. This structural design is crucial for preventing backflow of the isolation liquid. In actual operation, the liquid level in the isolation liquid container 2 fluctuates due to temperature changes or minor losses. By physically extending the outlet of the one-way valve 5 into the gas phase space, regardless of liquid level fluctuations, the outlet is always located in the gas region above the liquid surface, avoiding direct contact with the isolation liquid. This constructs a reliable physical barrier, completely eliminating the possibility of backflow of the isolation liquid through the one-way valve 5 during system shutdown or abnormal pressure.

[0035] Furthermore, the one-way valve 5 is preferably a constant-pressure one-way valve, configured to automatically open when the pressure in the isolation fluid container 2 is lower than a preset pressure. In this embodiment, the preset pressure is typically set to a value slightly higher than the pressure of the sealed medium to ensure that the pressure of the isolation fluid in the sealing chamber 1 is always higher than the process medium pressure, preventing medium leakage. When a minor leak occurs in the mechanical seal, leading to isolation fluid loss, or when the temperature decreases, causing the isolation fluid volume to shrink, the pressure in the isolation fluid container 2 will drop. Once the pressure falls below the set value of the constant-pressure one-way valve, the valve automatically opens, and the cooling fluid in the cooling fluid circuit replenishes the gas phase space, maintaining stable system pressure; when the pressure recovers, the valve automatically closes. This automatic pressure replenishment mechanism requires no manual intervention or additional pumping equipment, simplifying the system structure.

[0036] The cooling fluid circuit includes a cooling fluid inlet pipe 6 and a cooling fluid outlet pipe 7, each equipped with a flow indicator 8. The flow indicator 8 visually displays the flow state of the fluid within the pipes. Under normal operating conditions, the cooling fluid enters the heat exchange mechanism 3 via the inlet pipe 6, exchanges heat with the isolation fluid, and then flows out via the outlet pipe 7. At this time, the inlet and outlet flow rates are essentially balanced, and the flow rates displayed by the flow indicator 8 are consistent. When internal leakage occurs in the mechanical seal, the pressure inside the isolation fluid container 2 decreases, the one-way valve 5 opens, and a large amount of cooling fluid is replenished into the isolation fluid container 2 through the one-way valve 5, causing the flow rate in the cooling fluid inlet pipe 6 to be significantly greater than the flow rate in the cooling fluid outlet pipe 7. By comparing the flow rate difference between the two flow indicators 8, operators can visually determine that internal leakage has occurred in the seal, thus achieving real-time visual monitoring of the fault.

[0037] Specifically, the flow indicator 8 includes a first indicator installed on the cooling fluid inlet pipe 6 and a second indicator installed on the cooling fluid outlet pipe 7. By installing indicators on the inlet and outlet pipes respectively, operators can easily observe and compare the fluid flow status in the two pipes. In this embodiment, the flow indicator 8 is preferably a flow sight glass. A flow sight glass is a transparent observation window that can intuitively display whether fluid is present in the pipe, its flow rate, and whether the fluid is clean. It has the advantages of simple structure, low cost, and intuitive observation. It should be understood that in other embodiments, the flow indicator 8 can also be a flow meter or a flow velocity sensor, or other instrument that can reflect changes in flow rate, as long as flow velocity comparison can be achieved.

[0038] Regarding the heat exchange mechanism 3, in this embodiment, the heat exchange mechanism 3 is a coil-type heat exchanger installed inside the isolation liquid container 2, with the cooling fluid flowing within the coil-type heat exchanger. This built-in design integrates the heat exchange function inside the isolation liquid container 2. The cooling fluid flows inside the coil (tube side), and the isolation liquid flows in the container space outside the coil (shell side), exchanging heat through the coil wall. Compared to an external heat exchanger, this structure reduces external piping connection points, lowers the risk of external leakage, and makes the overall system structure more compact and occupies less space. It should be understood that the coil-type heat exchanger is only a preferred embodiment in this embodiment. In other embodiments, the heat exchange mechanism 3 can also be a plate heat exchanger or a shell-and-tube heat exchanger, as long as heat exchange between the isolation liquid and the cooling fluid can be achieved.

[0039] It should be understood that the cooling fluid in this embodiment can be clean water, ethylene glycol solution, or other suitable cooling media. Through the above structural design, this embodiment achieves closed-loop recycling of the isolation fluid, automatic pressure replenishment and contamination prevention, and visual alarm for leakage, and has the beneficial effects of compact structure, high safety, environmental protection and energy saving.

[0040] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention, such as replacing the flow sight glass with other types of flow indicators, or replacing the coil heat exchanger with other equivalent heat exchange structures, as long as these variations or substitutions do not depart from the technical concept of the present invention of simultaneously achieving cooling, pressure replenishment, and leakage monitoring using a cooling fluid circuit, should be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A flushing method for a mechanical seal, characterized in that, include: The separatory fluid circulates in the separatory fluid circulation loop to flush the mechanical seal; The cooling fluid flows through the heat exchange mechanism (3) to exchange heat between the isolation liquid and the cooling fluid; When the pressure of the isolation fluid circulation loop is lower than the preset pressure, the cooling fluid is replenished into the isolation fluid circulation loop in one direction through the one-way valve (5) on the cooling fluid loop, and the one-way valve (5) prevents the isolation fluid from flowing out in reverse; and The cooling fluid is made to flow through the cooling fluid circuit, and the cooling fluid circuit is provided with a flow indicator (8). The flow state of the cooling fluid is observed through the flow indicator (8) to detect sealing leaks based on the flow difference between the inlet and outlet of the cooling fluid circuit. The flow indicator (8) includes a first indicator installed on the cooling fluid inlet pipe (6) and a second indicator installed on the cooling fluid outlet pipe (7); The one-way valve (5) is installed on the cooling fluid circuit, and the outlet of the one-way valve (5) is connected to the gas phase space of the isolation liquid container (2).

2. The flushing method for the mechanical seal according to claim 1, characterized in that, The flow indicator (8) is a flow sight.

3. A mechanical seal flushing system, characterized in that, include: A sealed cavity (1) is configured to accommodate a mechanical seal assembly; A separating liquid container (2) is configured to contain a separating liquid, and the separating liquid container (2) is in communication with the sealing cavity (1); The heat exchange mechanism (3) is configured to allow the isolation fluid to exchange heat with the cooling fluid; A one-way valve (5) is installed in the cooling fluid circuit, and the outlet end of the one-way valve (5) is connected to the gas phase space of the isolation liquid container (2); the one-way valve (5) is a constant pressure one-way valve, which is configured to automatically open when the pressure of the isolation liquid container (2) is lower than a preset pressure; and The cooling fluid circuit includes a cooling fluid inlet pipe (6) and a cooling fluid outlet pipe (7), and flow indicators (8) are respectively provided on the cooling fluid inlet pipe (6) and the cooling fluid outlet pipe (7).

4. The mechanical seal flushing system according to claim 3, characterized in that, The one-way valve (5) is located on the top of the isolation liquid container (2), and the outlet end of the one-way valve (5) extends into the gas phase space of the isolation liquid container (2).

5. The mechanical seal flushing system according to claim 3, characterized in that, The heat exchange mechanism (3) is a coil heat exchanger installed in the isolation liquid container (2), and the cooling fluid flows in the coil heat exchanger.

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