German ALLWEILER seals ALLWEILER models ALLWEILER prices

ALLWEILER seals are sealing devices installed to prevent leakage between the pump shaft and the casing. Common types of shaft seals include packing seals, mechanical seals, and dynamic seals. The shaft seal of a reciprocating pump is usually a packing seal. When transporting media where leakage is not permitted, a diaphragm reciprocating pump can be used. The shaft seals of rotary pumps (including vane pumps, rotor pumps, etc.) mainly include packing seals, mechanical seals, and dynamic seals. The shaft seal of a reciprocating pump is usually a packing seal. When transporting media where leakage is not permitted, a diaphragm reciprocating pump can be used. The shaft seals of rotary pumps (including vane pumps, rotor pumps, etc.) mainly include packing seals, mechanical seals, and dynamic seals.

Function of ALLWEILER seals

Prevent high-pressure liquid from leaking out of the pump and prevent air from entering the pump. Although the shaft seal occupies a small space in the pump, the normal operation of the pump is closely related to the shaft seal. If the shaft seal is improperly selected, it will not only require frequent maintenance during operation and cause significant loss of the transported liquid, but may also cause fires, explosions, and poisoning accidents due to the leakage of flammable, explosive, and toxic liquids, with unimaginable consequences. Therefore, the shaft seal structure must be reasonably selected to ensure the safe operation of the pump. 1) Since the pressure inside the cylinder is not equal to the external atmospheric pressure, steam inside the cylinder or air outside the cylinder will inevitably leak out or in along the radial gap between the main shaft and the cylinder, causing working fluid loss, deteriorating the operating environment, and heating the shaft journal or allowing steam to enter the bearing chamber, causing oil quality deterioration. Leaking air also destroys the vacuum, thereby increasing the exhaust load, which will reduce the unit efficiency. For this reason, shaft seals are installed at both ends of the cylinder where the rotor passes through. This type of shaft seal is called an end shaft seal, abbreviated as shaft seal. High-pressure shaft seals are used to prevent steam from leaking out of the cylinder, and low-pressure shaft seals are used to prevent air from leaking into the cylinder. 2) During turbine operation, a portion of steam will inevitably leak from the shaft end to the atmosphere, causing loss of working fluid and heat, and also affecting the working environment of the turbogenerator. If the adjustment is improper and the steam leakage is excessive, it will also cause the temperature of the bearings near the shaft seal to rise or cause water to enter the bearing oil. For this reason, shaft seal heaters are installed in various units to recover and utilize the shaft seal leakage steam of the turbine. 3) Prevent steam inside the cylinder and valve stem leakage from leaking outward, polluting the turbine room environment and bearing lubricating oil quality. Prevent high-temperature steam from flowing over the turbine main shaft during normal unit operation, causing it to heat up, thereby causing bearing overheating. Prevent air from leaking into the vacuum part of the cylinder. Ensure the vacuum effect and degree of the condenser during unit startup. Recover shaft seal and valve stem leakage to reduce working fluid and energy losses. 4) During turbine tripping shutdown and the entire hot shutdown process where the condenser needs to maintain a vacuum, prevent air from leaking into the turbine, accelerating internal cooling of the turbine, causing main shaft bending.

ALLWEILER seal replacement steps

1) Remove the main pulley (belt drive) and remove the key pin; 2) Use a pin puller to remove the locating pins of the shaft seal end cover; 3) Remove the fixing screws of the shaft seal end cover; 4) Use a circular external puller to remove the shaft sleeve (if no puller is available, cut a groove on the shaft sleeve with a cutting machine and knock it down with a chisel; note to block sand with something to prevent it from getting into the screw rod); 5) Remove the old shaft seal; 6) Clean the shaft seal end cover and bearing positions, then clean with 755; 7) Apply 638 adhesive to the shaft seal installation position, then carefully install the shaft seal; note not to damage the rubber lip; you can apply some oil or high-temperature grease to the rubber surface of the shaft seal; 8) After cleaning the shaft sleeve position, reinstall and fix the end cover securely (you can wrap a layer of thick glossy paper around the shaft to prevent the shaft seal lip from accidentally touching the keyway during end cover installation); 9) Clean the new shaft sleeve and installation position, apply fixing adhesive 638 to the inner circle of the shaft sleeve. Cold fit: Use a force bar to evenly knock the shaft sleeve in; pad the outside of the new shaft sleeve with an outer ring of the same size to knock it in to avoid damaging the shaft sleeve. Hot fit: Clean the inside of the shaft sleeve thoroughly, ensuring no oil. Apply a ring of 638 adhesive to the shaft journal before the shaft seal, heat the shaft sleeve to 110 degrees, and install it. (Note: Push the shaft sleeve to the edge of the shaft seal, pause briefly. Wait for the temperature to drop before pushing it to the shaft seal position; 10) Install the pulley or coupling, correct parallelism or centerline, and manually reverse the machine head to allow lubricating oil to return to the front bearing and shaft seal.

ALLWEILER seal maintenance

1) Control of shaft seal pressure: High shaft seal pressure can easily cause steam emission from the shaft seal, easily leading to water ingress into the oil and deterioration of turbine oil quality. Excessively high shaft seal pressure will cause the equalizing box safety valve to actuate, wasting working fluid and damaging equipment. Too low shaft seal pressure may cause a decrease in unit vacuum, allowing cold air to enter the shaft seal or even the cylinder, causing cooling of the shaft seal section or inside the cylinder, seriously threatening equipment safety. 2) Impact of abnormal shaft seal temperature on the unit: When the shaft seal temperature is too high, especially before unit startup, if the temperature is too high, it will cause intense heating at the shaft end shaft seal and rotor shaft seal section, producing local stress concentration phenomena, thereby causing certain deformation, which may change the gap between the rotor and cylinder, increase shaft seal steam leakage, increase expansion difference, and in severe cases, may cause static and dynamic friction. When the shaft seal temperature is too low, it will cause cooling of the shaft end shaft seal and rotor shaft seal section; similarly, it will also produce local stress concentration phenomena, changing the gap between the cylinder and rotor, increasing shaft end leakage, and decreasing expansion difference. When the shaft seal temperature is too low, the shaft seal supply steam may carry water, causing water hammer in the shaft seal supply pipeline. In severe cases, it may cause water ingress into the turbine.

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