Seeking help: high bearing temperature in KSB heat transfer oil high-temperature pump
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Our company has a KSB high-temperature heat transfer oil pump, model SYT125-200. The temperature of the heat transfer oil is 270 degrees, and the pump has been in use for 6 years. It has received regular maintenance up to now. Recently, it was repaired due to leakage from the mechanical seal. After the pump was reassembled, preheated, and aligned, it was started up, but the following issues occurred: 1. The temperature of the graphite sliding bearing at the impeller end of the bearing housing was as high as 220 degrees, while the normal value should be around 150 degrees. 2. The temperature of the rolling bearing at the motor drive end was as high as 140 degrees, whereas it should be below 100 degrees under normal conditions. 3. The impeller shows no signs of wear, and the ring seals are in good condition; all the replacement parts used were original manufacturer parts. The pump rotates smoothly both when cold and when hot. I wonder if anyone with experience has dealt with this issue – could you please offer some advice? Question 1: I suspect that the high temperature is caused by either an excessive or insufficient clearance between the graphite sliding bearing and the pump shaft, which leads to a large amount of hot heat transfer oil entering the bearing housing area. The technical specifications for this pump indicate that the appropriate clearance should be between 0.08 and 0.13. I measured the actual clearance when the pump was cold, and it was around 0.1. I think that an insufficient clearance may be causing inadequate lubrication of the pump. However, since the pump was disassembled before, the graphite bearings showed no signs of wear. Would increasing the clearance between the graphite bearing and the shaft by 0.1 improve the pump’s performance? ? ? 、
Send over the pump’s structure diagram and parameters for a look
Please contact the KSB agent at phone number 13801677549; spare parts for standard models are in stock!
Question 1: I suspect that the high temperature is caused by an excessive or insufficient clearance between the end of the graphite sliding bearing and the pump shaft, which leads to a large amount of heat transfer oil entering the bearing housing. There should also be a packing seal; otherwise, the heat transfer oil would directly enter the bearing housing
We are using KSB ETNY 125-100-250 ETANORM SYT pumps; there are 5 pumps in total, and one of them also has high bearing temperature at the DE end.
My personal views are as follows: 1. Is there another shaft sleeve between the impeller and the graphite sleeve? What is the clearance between this shaft sleeve and the pump’s cover? It is recommended to check this clearance; the graphite sleeve shows no signs of wear, but the high temperature is likely caused by an excessive amount of fluid flowing past the back side of the impeller. 2. A high temperature in the motor bearings is likely related to the axial positioning of the rotor; it is recommended to recheck the positioning dimensions. 3. The shaft sleeve should have cooling water; it is recommended to check the cooling condition
Is the problem solved? Please share it in a timely manner
I also feel like it’s the temperature of the heat transfer oil that’s causing this issue. Could it be that the mechanical seal wasn’t adjusted properly during reassembly, resulting in some leakage? With this model of unit, mechanical seal leakage often occurs after reassembly or when the machine is restarted after being shut down
Look at the picture above – who knows what kind of pump it is?