What are the advantages of inlet guide vane control in turbines?
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I’ve noticed that in many turbine cases, the flow rate is controlled using guide vanes. What are the advantages of this approach? Is it stability and ease of adjustment? Then, is it possible to use ordinary self-regulating valves instead of guide vanes? What are the disadvantages of using self-regulating valves? Hope to help answer it
Reply 1# lizhenpeng: The vanes are installed near the inlet of compressors and fans, and they are generally used in units with low pressure, high flow rates, and large diameters. Their adjustment features high precision, a wide range of operation, low resistance, fast response, and minimal space requirement. Ordinary control valves do not possess these functions.
To be more specific, since the operating point is the intersection of the system resistance line and the compressor performance curve, there are roughly two main methods for adjusting the compressor’s flow rate: one is to adjust the system resistance line, and the other is to adjust the compressor performance curve. Throttling at both the inlet and outlet valves falls under the category of adjusting the system resistance, resulting in high power losses across the valves, which is uneconomical. Additionally, the operating point shifts away from the efficient point, and in severe cases, this can lead to surge. Both speed regulation and inlet vane adjustment are methods for shaping the performance curve of a compressor. It is important to note that inlet vane adjustment does not constitute throttling; rather, it changes the angle and speed at which the gas enters the impeller. The advantages of inlet vane adjustment include low energy loss and flexibility, as well as the ability to keep the operating point near the efficient range. However, its drawback is that in multi-stage compressors, it only affects the first impeller, and it is commonly used in axial flow compressors and modular compressors