Difference in functions between the emergency oil pump and the high-level oil tank
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Some large-scale power units are equipped with high-level oil tanks, which serve to ensure lubrication for the unit in case of failures of the main and auxiliary oil pumps. Some units also have emergency oil pumps, which again are intended to provide lubrication to enable a safe shutdown of the unit when the main and auxiliary oil pumps fail. What is the difference between the functions of these two types of pumps? Are there any particular considerations?
The high-level oil tank and the emergency oil pump serve the same purpose. However, in terms of safety, the high-level oil tank is more reliable; in the event of a power outage, the emergency oil pump cannot ensure proper lubrication of the machinery, whereas the high-level oil tank can. I’ve never seen an emergency oil pump; it seems to have a self-starting procedure with specific requirements regarding the timing of startup. The high-position oil tank has requirements regarding its height, which is determined by the lubricating oil pressure; it also has requirements as regards its volume, which is determined based on the drainage time and the amount of oil required per unit time. In addition, upper and lower oil pipelines are provided.
The emergency oil pump is usually a DC pump; it starts up when there is a failure in the low-voltage AC power supply used by the main and auxiliary oil pumps, serving alongside the high-level oil tank to provide emergency oil supply
Generally, a high-mounted oil tank is more desirable after the unit is shut down; its volume and height are determined to meet the requirements for lubrication and cooling of the equipment during the coasting period. An emergency oil pump should be used in cases where the on-site space does not permit the installation of a high-mounted oil tank
The purpose in each case is to ensure emergency operation of the unit’s lubrication system; it’s just that the methods differ and so do the effects
The emergency oil pump comes into operation when problems occur with the regular oil pump, while the high-level oil tank is designed to protect the compressor unit in the event of a power outage across the entire plant
The purpose of this design is to provide a double safety mechanism. The accident oil pump is activated when both main oil pumps stop at the same time; its power supply comes from an emergency power source or UPS. This means that in the event of a power outage or similar incident, the safety of these large-scale units is **enhanced** thanks to this double safety mechanism. Additionally, the emergency oil pump can also be used during the automatic barring of the unit and when both main oil pumps are under maintenance, thereby saving energy.
Nothing can be 100% perfect, which is why there are high-level fuel tanks and emergency fuel pumps; their existence is aimed at achieving perfection, but that is an ideal state that can never be reached. That’s just a side note. The high-level fuel tank serves to ensure the continuity of the fuel system in the event of a sudden power outage; the same is true for the emergency fuel pump. But if the emergency fuel pump has no electricity, what provides the power for it? I haven’t seen this configuration, so I wouldn’t dare to speak rashly; there are also main oil pumps that are powered by steam.
The high-level oil tank and the emergency oil pump serve exactly the same purpose: to prevent sudden accidents and ensure that the equipment has oil for lubrication in short periods of time. The high-level oil tank requires specific installation space; in some cases, it needs to be installed 12 meters above the center axis of the equipment, which makes it quite troublesome. The power supply for the emergency oil pump is usually provided by a UPS. In my opinion, the high-position oil tank is more reliable, but it is more difficult to install. It is necessary to choose which one to use based on the specific conditions at the site; using both would be somewhat redundant.
Emergency oil pump: Starts in case of failure of the main and auxiliary oil pumps. To ensure the normal operation of the unit. At this time, the emergency oil pump can basically ensure normal oil supply ； High-level fuel tank: This is mainly to account for the situation where the equipment loses power and the fuel pumps cannot start. It serves to cool the host as it slows down at high speeds. The purpose is to use oil normally during this deceleration process. Therefore, the oil level, oil pressure, and volume of the high-position fuel tank are all calculated.
The high-level oil tank and the emergency oil pump serve the same purpose: to ensure proper lubrication at all lubrication points of the unit and prevent failures caused by lack of oil. The only difference is that the emergency oil pump also has a function related to regulating the oil system. The difference lies in the function of the high-position fuel tank, which is to ensure proper lubrication at all lubrication points during the shutdown period following a failure of the main engine ； The emergency oil pump is a pump that comes into action when various failures occur in the main oil pump during normal operation, serving a similar role to a backup pump by ensuring a steady supply of oil.