Mechanical seal lubricating cooling system with sealing fluid
Sep 24, 2022
1. When the pump transports clean liquid, the sealing liquid is drawn from the pump discharge port, and the multi-stage pump can be drawn from the middle stage, and is connected to the sealing liquid inlet at the sealing liquid ring through the connecting pipe.
2. If any of the following conditions are met, an external sealing fluid system should be provided:
1. The suction height of the pump exceeds 4.5m. At this time, a large amount of air that has not been filtered will enter the pump through the stuffing box, which will greatly affect the normal operation of the pump. The sealing fluid pressure is 70~172kPa.
2. The discharge pressure is lower than 0.07MPa. Because the discharge pressure is too low, it is impossible to provide sufficient sealing fluid pressure at the discharge port of the pump.
3. The conveying hot water exceeds 120 ℃, and there is not enough cooling (except for the boiler feed pump, because it cannot use a liquid sealing ring).
4. When conveying solid abrasive media, such as mortar water and sewage, in order to prolong the service life of packing, shaft or bushing and reduce abrasion, it is necessary to pass clean liquid into the sealing liquid. The cleaning liquid can be supplied from the outside, and the external sealing liquid pressure should be greater than the pressure inside the packing chamber by 70~172kPa, but in order to reduce the dilution of the sealed medium, two rings of packing should be set between the liquid sealing ring and the inner end of the packing chamber; The liquid is drawn from the discharge port of the pump, passes through the filter or centrifugal separator, and enters the liquid sealing ring. There is a rubber pad between the liquid sealing ring and the shaft shoulder to prevent the flow of cleaning liquid and mud water, as shown in Figure 1. The rubber pad needs to match the inner diameter of the stuffing box and the outer diameter of the shaft or bushing.
5. The heat well pump and condensate pump operate at 710mmHg vacuum.
6. When transporting non-aqueous media, such as acid, gasoline, honey or viscous liquid, the design of the sealed chamber has not given special consideration to the characteristics of these liquids.
3. When the suction pressure of the pump is lower than atmospheric pressure, such as a condensate pump, a throttle orifice should be added to the return line of the sealing liquid to the suction port, that is, the sealing liquid will be drawn from the pump discharge port into the stuffing box, and the water coming out of the stuffing box will be The sealing liquid passes through the orifice plate and then flows into the suction port of the pump to prevent air from leaking into the pump and control the flow of the sealing liquid.
4. When the pressure of the medium in the sealing chamber is lower than 103kPa and the temperature is lower than 90℃, if a sufficient amount of leakage liquid passes through the packing seal, cooling measures are not required.
5. When the pressure of the medium in the sealing chamber is lower than 345kPa and the temperature is lower than 118℃, the cooling liquid needs to be passed into the sealing ring. The coolant flow is 3.78L/min, and the pressure is 34kPa lower than the medium pressure.
6. When the pressure of the medium in the sealing chamber is lower than 690kPa and the temperature is lower than 131℃, the cooling liquid needs to be passed into the sealing ring. The coolant flow is 3.78L/min, the pressure is 34kP lower than the medium pressure, and jacket cooling is also required at the packing.
7. If the sealed medium is easy to solidify, the sealed chamber must be heated before the pump is started. Steam or resistance heat tracing can be used at the sealed chamber.
8. If the sealed solid is dissolved, it may also cause wear problems. It is therefore necessary to increase or decrease the temperature of the sealed chamber to ensure complete dissolution of the solids.
