What are the standards for determining the height of the high-level oil sump in a turbine-compressor unit?
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I checked online and found the following view: the pressure difference between the high-level oil tank and the pressure point used for the unit’s low oil pressure shutdown protection (converted to pressure) must be lower than the value corresponding to the unit’s low oil pressure shutdown threshold. Otherwise, after the oil pump stops, the pressure generated due to the high location of the oil tank may exceed the shutdown pressure, causing the unit to continue operating – and the consequences of this would be severe. Is this standard correct?
No. The high-level fuel tank can supply fuel for 8 minutes. Ensure lubricant supply during the coasting time to prevent dry friction.
For accident tanks, API has standards. The height from the main machine’s centerline is 5 to 7 meters.
I think it’s correct; there is such a consideration because if the position is too high, it will result in excessive pressure, preventing the system from reaching the shutdown value, and thus the high-position tank will not achieve its intended function.
By considering the emergency fuel supply pressure on one hand, and the fuel supply volume (duration) on the other, it is possible to determine its height and volume fairly accurately~~
Currently, the lubricating oil pressure at the unit inlet and its duration are generally determined by the aperture of the orifice plate at the lubricating oil inlet; of course, it is also related to the height of the oil reservoir, although the height difference is not significant, so its impact should be minimal.
API is the standard of the American Petroleum Institute. General designs are based on this.
The function of the high-level oil tank is to supply lubricating oil to the machinery in case of a sudden power outage or damage to the oil pump. By utilizing the gravitational potential energy resulting from the height difference, sufficient oil is provided to the bearing shells, ensuring that the turbine and centrifuge can stop urgently without the bearings suffering from dry friction due to a lack of oil. This helps to provide lubrication and cooling. To prevent the shaft bearings from being damaged, it provides lubrication for the equipment bearings during the period when the unit is running at idle speed, thereby protecting the shafts and bearings after the low lubricating oil pressure interlock is activated. Under normal conditions, the lubricating oil enters the high-level oil tank through a flow-limiting orifice plate, and then returns to the tank via a high-level overflow pipe, thereby ensuring the renewal of the lubricating oil in the high-level oil tank. In an emergency situation, the lubricating oil in the upper oil tank flows back to the bearings through check valves to lubricate them. Generally, the oil storage capacity of the upper oil tank should be sufficient to last for about 5 to 8 minutes.
This situation generally does not occur, unless the design is not followed and construction is not carried out according to the design.