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What are the problems exposed in the use of single-end bellows mechanical seal system? -
by：Lepu Seal
2021-06-01
What are the problems exposed in the use of single-end bellows mechanical seal system?
2020-05-08
What are the problems exposed in the use of single-end face bellows mechanical seal system:
The statistical results show that the service life of the high temperature oil pump mechanical seal can reach more than one year under the condition of ensuring the normal operation of the auxiliary system and the stable operation of the pump. However, with the continuous improvement of energy saving and emission reduction requirements in modern industrial production, the use of single-end bellows-type mechanical seals and auxiliary systems can no longer meet the requirements. The main problems exposed are:
①Using the existing mechanical seal and its auxiliary system, during the operation of the high-temperature oil pump, variable working conditions may occur from time to time. Pump evacuation, misoperation, artificial flow adjustment, etc. all make the mechanical seal under variable working conditions. .When the pressure of the sealed medium fluctuates drastically, it can cause the mutual impact of the friction pair, causing end face damage, thereby affecting the sealing effect; if the operating pressure of the sealed cavity fluctuates and becomes negative pressure instantly, the bellows shrinks and cannot be restored in time, and the movement , The oil film seal formed between the static ring friction pair is destroyed, causing sudden leakage failure.
②The temperature of the working medium is very high, coupled with the frictional heat of the end face of the seal friction pair, once the flushing system fails, the end face temperature will rise sharply, causing the end face liquid film to vaporize and cause dry friction, which can cause the seal to fail in a short time ; Secondly, high temperature can also reduce the performance of the graphite ring, and in severe cases, the impregnant can be melted; thirdly, when the moving and static ring materials are paired with tungsten carbide and graphite, the high temperature can also cause rings on the surface of the graphite ring (stationary ring). The tungsten carbide (moving ring) is also easy to fall off because of the grooves; finally, the friction pair has a large thermal deformation at high temperature, which changes the friction state of the end face, leading to premature failure of the sealing system.
③High operating cost and large energy consumption. For the atmospheric and vacuum tower bottom residual oil pump, the external flushing scheme 32 is adopted, and the flushing liquid directly enters the process medium, which causes a large consumption and a high production cost. For example, there are two reducing bottom pumps in a factory's atmospheric and vacuum equipment, and one pump has more than 20 tons of wax oil injected into the heavy oil rendering system every day. If the difference between heavy oil and wax oil is 1000 yuan/ton, the daily economic loss is estimated to be 20x1000 u003d 20,000 yuan. The annual loss is 20,000 yuan X360 u003d 7.2 million yuan. Using the self-flushing scheme 21 to cool the high-temperature medium before injecting it into the pump will inevitably consume a lot of heat and reduce the efficiency of the pump. At the same time, the amount of cooling water consumed is also quite large.
④ In both scheme 21 and scheme 32, the back of the mechanical seal static ring must be cooled by rapid cold water. Its function is to cool the friction pair of the dynamic and static ring, thereby reducing the friction between the bellows and the friction pair to a certain extent. The temperature provides a suitable operating environment for the mechanical seal to prevent high temperature deformation or failure of mechanical seal components, so as to achieve the purpose of improving the sealing effect and prolonging the service life. However, because the cooling water scales on the high-temperature parts, and the scale is located between the dynamic and static ring friction pairs and the shaft sleeves that are close to them and the wave plate of the corrugated tube, the corrugated tube loses its elasticity and fails. 1133.html,
What are the bellows mechanical seal solutions for high temperature hot oil pumps? What are the main forms of seal failure caused by the bellows mechanical seal and its auxiliary system currently used?
2020-05-08
What are the problems exposed in the use of single-end face bellows mechanical seal system:
The statistical results show that the service life of the high temperature oil pump mechanical seal can reach more than one year under the condition of ensuring the normal operation of the auxiliary system and the stable operation of the pump. However, with the continuous improvement of energy saving and emission reduction requirements in modern industrial production, the use of single-end bellows-type mechanical seals and auxiliary systems can no longer meet the requirements. The main problems exposed are:
①Using the existing mechanical seal and its auxiliary system, during the operation of the high-temperature oil pump, variable working conditions may occur from time to time. Pump evacuation, misoperation, artificial flow adjustment, etc. all make the mechanical seal under variable working conditions. .When the pressure of the sealed medium fluctuates drastically, it can cause the mutual impact of the friction pair, causing end face damage, thereby affecting the sealing effect; if the operating pressure of the sealed cavity fluctuates and becomes negative pressure instantly, the bellows shrinks and cannot be restored in time, and the movement , The oil film seal formed between the static ring friction pair is destroyed, causing sudden leakage failure.
②The temperature of the working medium is very high, coupled with the frictional heat of the end face of the seal friction pair, once the flushing system fails, the end face temperature will rise sharply, causing the end face liquid film to vaporize and cause dry friction, which can cause the seal to fail in a short time ; Secondly, high temperature can also reduce the performance of the graphite ring, and in severe cases, the impregnant can be melted; thirdly, when the moving and static ring materials are paired with tungsten carbide and graphite, the high temperature can also cause rings on the surface of the graphite ring (stationary ring). The tungsten carbide (moving ring) is also easy to fall off because of the grooves; finally, the friction pair has a large thermal deformation at high temperature, which changes the friction state of the end face, leading to premature failure of the sealing system.
③High operating cost and large energy consumption. For the atmospheric and vacuum tower bottom residual oil pump, the external flushing scheme 32 is adopted, and the flushing liquid directly enters the process medium, which causes a large consumption and a high production cost. For example, there are two reducing bottom pumps in a factory's atmospheric and vacuum equipment, and one pump has more than 20 tons of wax oil injected into the heavy oil rendering system every day. If the difference between heavy oil and wax oil is 1000 yuan/ton, the daily economic loss is estimated to be 20x1000 u003d 20,000 yuan. The annual loss is 20,000 yuan X360 u003d 7.2 million yuan. Using the self-flushing scheme 21 to cool the high-temperature medium before injecting it into the pump will inevitably consume a lot of heat and reduce the efficiency of the pump. At the same time, the amount of cooling water consumed is also quite large.
④ In both scheme 21 and scheme 32, the back of the mechanical seal static ring must be cooled by rapid cold water. Its function is to cool the friction pair of the dynamic and static ring, thereby reducing the friction between the bellows and the friction pair to a certain extent. The temperature provides a suitable operating environment for the mechanical seal to prevent high temperature deformation or failure of mechanical seal components, so as to achieve the purpose of improving the sealing effect and prolonging the service life. However, because the cooling water scales on the high-temperature parts, and the scale is located between the dynamic and static ring friction pairs and the shaft sleeves that are close to them and the wave plate of the corrugated tube, the corrugated tube loses its elasticity and fails. 1133.html,
What are the bellows mechanical seal solutions for high temperature hot oil pumps? What are the main forms of seal failure caused by the bellows mechanical seal and its auxiliary system currently used?
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