Differences in starting up turbine-driven centrifugal compressor units and motor-driven centrifugal compressor units
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Turbine-type centrifugal compressor units are more frequently used in practice, and their startup is more complicated, mainly due to the turbine component； Motor-driven systems are relatively rare; I’ve hardly come across them. In my opinion, for the purpose of protecting against starting currents, guide vanes are usually installed at the compressor inlet. During startup, these inlet guide vanes are closed to a small degree, but the motor starts up very quickly. How are these guide vanes operated? Let’s discuss it together.
The usual inlet guide vane angle is around 10 to 15 degrees. It is mainly to reduce the impact of the motor’s starting current on the power grid.
Reply to 2# Power Center: Um, thank you. However, I have a question: after the motor starts working properly and loading begins, there should be a relatively smooth process, otherwise the shaft displacement of the compressor might change significantly. Other factors include bearing temperature and vibration; compared to turbocentrifugal compressors, these aspects are much simpler to deal with, as there is no issue of transcritical conditions.
Reply to 3# julius6054 to see what model you have. Compressed air, carbon dioxide units. It’s more or less the same. Start up normally by gradually opening the inlet guide vanes, and monitor the current and pressure.
Domestic compressors generally start under light load, after which the guide vanes are gradually adjusted to help the unit move past the surge line. At this time, it is important to monitor changes in vibration, shaft temperature, as well as oil pressure and oil temperature; in particular, the oil temperature needs to be regulated smoothly and promptly. It is best to run a cold chiller unit for a while before loading it, as this is beneficial for the machine.
Motor-driven compressors, including synchronous motors and asynchronous motors； Generally, starting a motor driven by an asynchronous motor is much simpler
Reply to 6# Universe’s Dawn: I’m not very familiar with synchronous motors and asynchronous motors. Could we discuss this in more detail?
I’m not very familiar with compressors driven by motors, but I feel that there are significant differences between those driven by turbines and those driven by motors, especially in terms of the speed at which they accelerate during operation, the startup procedures, and energy consumption
There are also many motor-driven ones that do not have guide vanes, while there are many turbine-driven ones that do have guide vanes. In fact, as a driving mechanism, if the motor is equipped with other speed control mechanisms, it is not easier to operate than a turbine. Some speed control mechanisms have very strict requirements regarding acceleration performance.
Reply to 4# Power Center: They are all air compressors, with a pressure head of 45 kilograms and a flow rate of 230,000 standard cubic meters per hour.
Reply to 5# Universe’s Dawn: For air compressors, the common anti-surge design involves simply venting air. What puzzles me is this: once the motor starts, its speed reaches the operating speed in a short time. Apart from paying close attention to the motor’s starting current at the moment of startup, does monitoring the compressor – especially axis displacement – require careful handling?