Reasons for the temperature rise of steam turbine thrust bearings
Thread Content
I have a question about the relationship between the steam turbine thrust bearing temperature and the turbine exhaust pressure. The steam turbine thrust bearing temperature in our workshop generally runs at 74°C and slowly rises to 90°C. If it reaches 115°C, the interlocking steam turbine will trip. Currently, the steam turbine load and air cooler load are controlled. If the thrust bearing temperature is lowered to below 90°C, the exhaust pressure will increase significantly, causing the turbine speed control valve to open wide and the amount of cleaning to increase? Can anyone explain the relationship between the thrust bearing temperature and exhaust pressure of a Yiha steam turbine?
Generally speaking, as the load increases, the bearing capacity will also increase, and the bearing temperature may increase, but generally it will not increase so much. I see that your thrust bearing has two temperature measurement points. One point is higher, but the other one is still quite good. The vibration value of the bearing bush is not large. It is recommended to judge whether the displayed value is accurate first. If conditions permit (unlock the chain at this point), invert the lines on both sides to see if there is a change in temperature. You can also check the return oil temperature. If the bearing temperature vibration is high, the return oil temperature will also increase.
How long has the turbine been running? The temperature of the auxiliary thrust bearing shows 48 degrees, which is close to the inlet temperature of the lubricating oil. The thrust bearing gap may be large. In addition, the temperature difference between the two tiles on the support side bearing is relatively large. The temperature measurement point on the joint side is not displayed. There are also some abnormalities in the bearing temperature of the compressor. Find time to stop and check!
Axial force and flow are related
Judging from the data in the figure, one side is too high and the working conditions are stable. How much does the data fluctuate up and down at this point? If the fluctuation is larger than others, it should be an instrument failure. Let the instrument see if the existing point is loose. You can also swap the corresponding temperature point to see if there is any problem with the channel. We had a similar phenomenon before. It was an installation problem with the instrument probe. The single point was too high. Everything else was normal.,,
If you are afraid of interlocking tripping due to temperature rise, you can modify the interlocking logic to a two-out-of-two method, because this is safer and can avoid unnecessary interlocking tripping due to instrument point problems, causing economic losses.
High exhaust steam temperature increases axial thrust.
Your point with a high temperature is probably the point of the secondary push point. One of the two points is high and the other is normal. First check whether this measuring point is normal. In addition, whether the temperature change is accompanied by a change in shaft displacement, a spectral analysis of the lubricating oil return is performed to determine whether the bearing bush is worn. As the amount of steam increases, the axial force will increase in the direction of positive displacement.
You first check whether the displacement of the turbine changes when the temperature rises, then exchange the two measuring points to see which one is higher, and also check whether the resistance of this high value is normal. If everything is normal, it means it is really high. If the temperature at this measuring point slowly rises, in this case there should be scale on the tile. Don't worry too much about changing the chain to 2 out of 2, it will probably be fine once the temperature gets close to 100. Always control the oil temperature.