Does anyone know how to calculate the oil level maintenance time for large mechanical equipment (compressors, high-pressure pumps)?
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The high-level oil tank of large rotating equipment (compressors, high-pressure pumps) allows the stored oil to be used to bring the unit to a safe stop in the event of an interlocked shutdown; but how is the height of this high-level oil tank and the duration for which it can provide support determined?
It is calculated based on the product of the unit’s instantaneous oil consumption and the duration it needs to be maintained. Most have empirical formulas from various manufacturers.
It ranges from 5 to 10 minutes; the larger the fuel tank, the longer the time required, of course
I just want to know this empirical formula – how exactly are these two values calculated?
I checked the relevant sections of 4.9 in Chapter 2 of API 618, version 2008, and found the following useful information for reference: 1. High-level oil tanks can be divided into two types; one of them is called a high-level sealed oil tank； A lubricating oil tank for parking use ； 2. For tanks used for high-position sealing, it is generally specified that there should be enough oil to maintain the supporting condition for 2 minutes above the low liquid level alarm limit. Below the alarm limit and above the very low liquid level, there should be a flow rate of 10 minutes (plus sufficient time). The provisions for special circumstances can also refer to the remaining part of this clause ； 2. For lubrication oil tanks used for parking, when installed separately, they shall supply the lubricating oil required for the idling time specified by the buyer (Note 1); the tank specifications shall be designed to ensure a normal lubricating oil flow rate of at least 3 minutes. Note 1: The buyer here refers to the equipment integrator, as opposed to the lubricant skid – it is not the design institute. For example, Sulzer needs to purchase a lubricating oil system for the system, which includes a lubricating oil tank for use during shutdowns; Sulzer determines the idling time based on the characteristics of the system. For more information, it is recommended to read API 618 directly. We can discuss any unclear points together.
The inert time of the high-level fuel tank is 6 minutes
The fuel supply duration from the high-level tank must be longer than the idling time of the unit.
Generally, the maintenance time is set at 30 minutes, and the tank height and capacity must be calculated based on the unit’s requirements.
Could you give an example to illustrate the calculation process and formulas? What I want to know is this; it’s okay even if the data isn’t accurate
Hehe, there’s a shortcut here: you can check the parameters of the lubricant pump, namely the flow rate; just multiply that flow rate by the time
Personal opinion: First, you need to know the idling time of your machine; you can refer to the vibration trend when the machine is shut down – the time it takes for the vibration to drop back to zero is the machine’s idling time. The size of the high-level oil tank is determined by the amount of oil in the main oil pump multiplied by the idling time, and its height is 5 meters higher than the highest oil inlet point of the compressor.