Cooling water supply device for mechanical seal

Abstract

A mechanical seal cooling water supply device comprises a buffer tank, a water inlet and a water outlet are formed in the buffer tank, a floating ball valve and a double-floating-ball liquid level switch are arranged in the buffer tank, a ground discharging valve is arranged at the bottom of the buffer tank, and an overflow pipe is connected to the top of the buffer tank; a centrifugal pump is arranged below the buffer tank, a mechanical sealing device is arranged in the centrifugal pump, and the buffer tank is connected with a cooling water inlet of the mechanical sealing device through a water outlet pipe. The buffer tank supplies cooling water to the centrifugal pump through gravity, the floating ball valve is used for controlling the liquid level of the buffer tank, the supply pressure of the cooling water is constant, and stable operation of the pump is guaranteed. When the water pressure is too low, the PLC immediately sends out alarm information of'water shortage of mechanical seal cooling water 'and sends out a control signal to shut down centrifugal pump equipment at the same time, so that the mechanical seal device is prevented from being damaged due to water shortage.

Description

Technical Field

[0001] The utility model relates to the field of physics, in particular to a mechanical sealing device of a centrifugal pump, in particular to a mechanical sealing cooling water supply device. Background Art

[0002] A mechanical seal is used to seal the pump shaft and pump body of a centrifugal pump to prevent fluid leakage. The end faces of the dynamic ring and the static ring of the mechanical seal need to maintain a liquid film. Cooling water is introduced into the mechanical seal to form a liquid film, which plays a role in sealing, cooling and lubricating the surface. In the prior art, the water pressure of the factory's water supply main often fluctuates. If the water pressure is too low and the cooling water is cut off, the liquid film cannot be formed, which will cause dry grinding of the mechanical seal end face, aggravating the wear of the end face, generating a large amount of frictional heat, and raising the temperature, leading to damage to the mechanical seal. If the water pressure is too high, it will accelerate the wear of the mechanical seal, and at the same time, the water consumption will also increase, and the equipment operating cost will increase. Summary of the invention

[0003] The utility model aims to provide a mechanical seal cooling water supply device, which is intended to solve the technical problem in the prior art that the unstable cooling water pressure affects the normal use of the mechanical seal device.

[0004] The utility model discloses a mechanical seal cooling water supply device, comprising a buffer tank, the buffer tank is provided with a water inlet and a water outlet, a float valve and a double float liquid level switch are provided in the buffer tank, a drain valve is provided at the bottom of the buffer tank, and an overflow pipe is connected to the top of the buffer tank;

[0005] The double float liquid level switch comprises an upper float switch and a lower float switch, the upper float switch is located above the lower float switch, the overflow pipe is located above the upper float switch, the float valve is located between the upper float switch and the lower float switch, the water outlet of the buffer tank is located below the lower float switch, and the drain valve is located below the water outlet of the buffer tank;

[0006] The water inlet and the water outlet of the cache tank are respectively connected to a water inlet pipe and a water outlet pipe, one end of the water inlet pipe is connected to a water source, and the other end of the water inlet pipe is connected to the water inlet end of the float valve, and a manual valve, a filter, and a pneumatic angle seat valve are sequentially arranged on the water inlet pipe along the water flow direction, a centrifugal pump is arranged below the cache tank, and a mechanical sealing device is arranged in the centrifugal pump, the cache tank is connected to the cooling water inlet of the mechanical sealing device through the water outlet pipe, and a flow meter is arranged on the water outlet pipe;

[0007] The double-float liquid level switch, the signal output end of the flow meter, and the control end of the pneumatic angle seat valve are all connected to a controller.

[0008] Furthermore, the height difference between the water outlet of the cache tank and the cooling water inlet of the mechanical sealing device is less than or equal to 2m.

[0009] Furthermore, the flow meter is a vortex flow meter.

[0010] Furthermore, the pneumatic angle seat valve includes a mechanical limiting mechanism.

[0011] Furthermore, the manual valve is a ball valve.

[0012] Furthermore, the filter is a Y-type filter.

[0013] Furthermore, the controller is a PLC.

[0014] Compared with the prior art, the utility model has a positive and obvious effect. The utility model is a mechanical seal cooling water supply device. The buffer tank supplies cooling water to the centrifugal pump by gravity, and the float valve is used to control the liquid level of the buffer tank, so that the cooling water supply pressure is relatively constant, ensuring the stable operation of the pump. When the water pressure is too low, the PLC immediately sends an alarm message of "mechanical seal cooling water shortage", and at the same time sends a control signal to shut down the centrifugal pump equipment to prevent the mechanical seal device from being damaged due to lack of water. If the float valve fails, the liquid level can also be controlled by the double float liquid level switch and the start angle seat valve to ensure the stable operation of the pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The utility model is a schematic diagram of a mechanical seal cooling water supply device.

[0016] Figure 2 It is a schematic diagram of a buffer tank in a mechanical seal cooling water supply device of the utility model. DETAILED DESCRIPTION

[0017] The present invention is further described below in conjunction with an embodiment, but the present invention is not limited to the embodiment. Any similar structure and similar changes of the present invention should be included in the protection scope of the present invention. The use of directions such as up, down, front, back, left, and right in the present invention is only for the convenience of clear description and is not a limitation on the technical solution of the present invention.

[0018] like Figure 1 and Figure 2 As shown, a mechanical seal cooling water supply device of the utility model comprises a buffer tank 3, a water inlet 7 and a water outlet 8 are arranged on the buffer tank 3, a float valve 9 and a double float liquid level switch 10 are arranged in the buffer tank 3, a drain valve 11 is arranged at the bottom of the buffer tank 3, and an overflow pipe 12 is connected to the top of the buffer tank 3;

[0019] The double float liquid level switch 10 includes an upper float switch 101 and a lower float switch 102, the upper float switch 101 is located above the lower float switch 102, the overflow pipe 12 is located above the upper float switch 101, the float valve 9 is located between the upper float switch 101 and the lower float switch 102, the water outlet 8 of the buffer tank 3 is located below the lower float switch 102, and the drain valve 11 is located below the water outlet 8 of the buffer tank 3;

[0020] The water inlet 7 and the water outlet 8 of the cache tank 3 are respectively connected to the water inlet pipe 13 and the water outlet pipe 14, one end of the water inlet pipe 13 is connected to the water source, and the other end of the water inlet pipe 13 is connected to the water inlet end of the float valve 9, and the manual valve 6, the filter 5, and the pneumatic angle seat valve 4 are sequentially arranged on the water inlet pipe 13 along the water flow direction, and a centrifugal pump 1 is arranged below the cache tank 3, and a mechanical sealing device is arranged in the centrifugal pump 1. The cache tank 3 is connected to the cooling water inlet of the mechanical sealing device through the water outlet pipe 14, and a flow meter 2 is arranged on the water outlet pipe 14;

[0021] The double-float liquid level switch 10, the signal output end of the flow meter 2, and the control end of the pneumatic angle seat valve 4 are all connected to a controller.

[0022] Furthermore, the height difference 15 between the water outlet 8 of the cache tank 3 and the cooling water inlet of the mechanical seal device is less than or equal to 2 m, ensuring that the static pressure of the cooling water at the mechanical seal is less than 0.2 bar and the pressure is relatively stable.

[0023] Furthermore, the flow meter 2 is a vortex flow meter, which is used to measure and monitor the current water flow and the total water consumption.

[0024] Furthermore, the pneumatic angle seat valve 4 includes a mechanical limit mechanism, which can accurately control the maximum opening degree of the pneumatic angle seat valve 4, achieve soft and stable water inlet, and avoid excessive opening resulting in excessive flow or pressure fluctuations.

[0025] Furthermore, the manual valve 6 is a ball valve.

[0026] Furthermore, the filter 5 is a Y-type filter.

[0027] Furthermore, the controller is a PLC.

[0028] Specifically, the float valve 9, double float liquid level switch 10, drain valve 11, pneumatic angle seat valve 4, centrifugal pump 1, mechanical sealing device, controller, vortex flowmeter, mechanical limit mechanism, Y-type filter, PLC, etc. in this embodiment all adopt well-known solutions in the prior art, which are well understood by those skilled in the art and will not be described in detail here.

[0029] The working principle of this embodiment:

[0030] When using for the first time, the drain valve 11 of the buffer tank 3 needs to be opened several times to drain all the particulate impurities in the water. For subsequent use, the drain valve 11 needs to be opened regularly to clean out the impurities. The impurities trapped by the filter screen of the filter 5 on the upstream water supply line also need to be cleaned regularly.

[0031] The first liquid level line of the cache tank 3 from high to low is the upper float liquid level line of the double float liquid level switch 10, and the normal liquid level is lower than this liquid level line. The second liquid level line is the liquid level line of the float valve 9, which is the normal working liquid level line. When the float valve 9 is working normally, the liquid level of the cache tank 3 is maintained at the second liquid level line. The third liquid level line is the liquid level displayed by the lower float of the double float liquid level switch 10, which is located below the second liquid level line. When working normally, the lower float always outputs a liquid level signal.

[0032] Before the device is operated, open the manual valve 6. Under the control of the PLC, open the pneumatic angle seat valve 4, and let water in through the water inlet pipe 13 and the float valve 9. The solid particle impurities in the cooling water are filtered through the filter 5 and flow into the buffer tank 3 through the float valve 9. The liquid level gradually rises to the liquid level limit of the float valve 9. The cooling water in the buffer tank 3 flows by gravity through the outlet pipe 14 to the mechanical seal device of the centrifugal pump 1. The outlet 8 of the buffer tank 3 is higher than the sewage outlet at the bottom, which can ensure that the outlet 8 flows out clean and precipitated cooling water. The float valve 9 automatically adjusts the water inlet according to the liquid level of the buffer tank 3 to maintain the liquid level on the liquid level line of the float valve 9. When the liquid level of the buffer tank 3 is higher than the liquid level line of the float valve 9, the float valve 9 is closed and the water inlet stops. When the liquid level of the buffer tank 3 is lower than the liquid level line of the float valve 9, the float valve 9 is opened to allow water inlet. When the cache tank 3 operates normally, the liquid level is higher than the liquid level line of the lower float switch 102 and lower than the liquid level line of the upper float switch 101. At this time, the lower float switch 102 always outputs a signal to the PLC, and the upper float switch 101 has no output signal, indicating that the water level in the cache tank 3 is normal.

[0033] If the water pressure drops for some reason (such as a pipe rupture, water source interruption, etc.), the water level in the buffer tank 3 drops below the lower float switch 102, causing the signal of the lower float switch 102 to disappear, and the PLC immediately issues an alarm message of "mechanical seal cooling water shortage" and sends a control signal to shut down the centrifugal pump 1 to prevent the mechanical seal from being damaged due to lack of water.

[0034] On the other hand, if the water level in the cache tank 3 rises to the liquid level line position of the upper float switch 101, it indicates that the float valve 9 may have failed and cannot correctly adjust the water intake. At this time, the upper float switch 101 sends a signal. After receiving this signal, the PLC switches to the standby control mode. In the standby control mode, the PLC will control the high and low liquid levels of the cache tank 3 by controlling the switch of the pneumatic angle seat valve 4. Specifically, when the water level reaches the liquid level line of the upper float switch 101, the PLC will close the pneumatic angle seat valve 4 to prevent further water inflow; when the water level drops to the liquid level line of the lower float switch 102, the PLC will reopen the pneumatic angle seat valve 4 to allow water inflow. In this way, even if the float valve 9 fails, the water level in the cache tank 3 can be guaranteed to be within a safe range. At the same time, when the PLC switches to the standby control mode, it will issue an alarm message of "float valve 9 failure" to prompt the operator to check and repair the float valve 9. This ensures that even if the float valve 9 fails, the problem can still be discovered in time and corresponding measures can be taken to ensure the normal operation of the entire water supply device.

[0035] When the centrifugal pump 1 stops, the PLC closes the pneumatic angle seat valve 4 on the main water supply line. The tank body is made of stainless steel, with a small volume and easy installation. The overflow pipe 12 can relieve the pressure of the upstream water supply and is also used for ventilation inside and outside the buffer tank 3 when the liquid level rises and falls. The manual valve 6 is usually open and closed when the device needs maintenance.

Claims

1. A mechanical seal cooling water supply device, characterized in that: It includes a cache tank, which is provided with a water inlet and a water outlet, a float valve and a double float liquid level switch, a drain valve at the bottom of the cache tank, and an overflow pipe connected to the top of the cache tank; The double float liquid level switch comprises an upper float switch and a lower float switch, the upper float switch is located above the lower float switch, the overflow pipe is located above the upper float switch, the float valve is located between the upper float switch and the lower float switch, the water outlet of the buffer tank is located below the lower float switch, and the drain valve is located below the water outlet of the buffer tank; The water inlet and the water outlet of the cache tank are respectively connected to a water inlet pipe and a water outlet pipe, one end of the water inlet pipe is connected to a water source, and the other end of the water inlet pipe is connected to the water inlet end of the float valve, and a manual valve, a filter, and a pneumatic angle seat valve are sequentially arranged on the water inlet pipe along the water flow direction, a centrifugal pump is arranged below the cache tank, and a mechanical sealing device is arranged in the centrifugal pump, the cache tank is connected to the cooling water inlet of the mechanical sealing device through the water outlet pipe, and a flow meter is arranged on the water outlet pipe; The double-float liquid level switch, the signal output end of the flow meter, and the control end of the pneumatic angle seat valve are all connected to a controller.

2. A mechanical seal cooling water supply device according to claim 1, characterized in that: The height difference between the water outlet of the cache tank and the cooling water inlet of the mechanical sealing device is less than or equal to 2m.

3. The mechanical seal cooling water supply device according to claim 1, characterized in that: The flow meter is a vortex flow meter.

4. The mechanical seal cooling water supply device according to claim 1, characterized in that: The pneumatic angle seat valve includes a mechanical limiting mechanism.

5. The mechanical seal cooling water supply device according to claim 1, characterized in that: The manual valve is a ball valve.

6. The mechanical seal cooling water supply device according to claim 1, characterized in that: The filter is a Y-type filter.

7. The mechanical seal cooling water supply device according to claim 1, characterized in that: The controller is a PLC.

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