Control principle of the compressor inlet guide vane valve

The inlet guide vane (IGV) located before the first-stage impeller not only expands the operating range of the compressor but also optimizes its performance under conditions other than those for which it was designed. The zero position of the guide vanes is when they are parallel to the direction of gas flow, and the guide vanes can achieve both positive and negative pre-rotation. The automatic control device of the IGV enables the compressor to operate under constant outlet pressure, regardless of different air flow requirements. The expected performance curve of a certain centrifuge is shown in the figure. The horizontal axis represents the flow rate of the unit, while the vertical axis typically indicates the pressure at the fan outlet or the pressure ratio (exit pressure to inlet pressure). The curve depicts the performance at different opening degrees of the IGV; a negative pre-swirl value corresponds to the maximum flow rate.

I have used Atlas turbo compressors; the vanes are controlled by control valves, and they are similar to airplane propellers – the control valves regulate the angle of the vanes in order to adjust the amount of air intake

Currently, the guide vanes available on the market usually come in five or eight pieces. The control mechanisms are of either pneumatic or electric type, and both types include positioners and adjustment functions; Fisher products are the most common