Axial and vertical coordinates of the compressor anti-surge curve

The horizontal and vertical axes represent pressure and throat clearance, as well as pressure and flow rate; the surge curve is determined based on the unit pressure values

The horizontal axis represents the pressure ratio of the outlet to the inlet, while the vertical axis represents the flow rate

a. Pd refers to the compressor outlet pressure, PS refers to the compressor inlet pressure, and h refers to the percentage of the compressor inlet flow rate. The surge condition of the unit is predicted based on the measured outlet pressure, inlet pressure, and inlet flow rate. b. When the operating point is to the right of the control line, there is a fixed difference between the setpoint of the surge controller and the current flow rate. When the operating point moves toward the surge region at a faster speed than the tracking point moves, the proportional output quickly opens the reverse flow valve, causing the setpoint to decrease at the same rate, until the reverse flow valve opens and a new operating point is established. c. Surge prevention: If surge occurs in the unit, the surge controller activates the anti-surge control valve to open rapidly until the surge is eliminated, after which it closes slowly; this valve features rapid opening and slow closing. d. Proportional output: The system features a pure proportional control function that forces the counter-rotation valve to open, regardless of the action of the controller at that time ； As the operating point moves toward the surge region and reaches a certain set range, the anti-surge valve begins to open; when the operating point reaches the surge line, the anti-surge valve opens 100%. That is: as the operating point moves to the left, the backflow valve is opened in proportion to the movement. e. During normal operation, the output of the anti-surge valve controller and the proportional output are compared; the anti-surge valve follows the signal from the one with the higher value. f. Under normal operation, it is set in semi-manual mode; both the semi-manual controller and manual control can be used to adjust the anti-surge valve, though manual adjustment cannot result in a value lower than that set by the controller. With manual control, the operator adjusts the anti-surge valve manually based on the operating point. The automatic mode is generally not recommended due to issues with instrument reliability. g. Each time surge occurs, the anti-surge control line and the margin line shift to the right by 2% each time; each such shift results in an accumulation of the amount by which they have moved. At the same time, record the surge count and the change in color of the surge indicator ； By pressing the reset button, the anti-surge control line and the margin line return to their state before surge occurred.

Could you explain what a reverse flow valve is?

First, understand what \"flying motion\" means – it is the same as surge; in the past it was more often referred to as flying motion, but these days it is generally called surge. Counter-flying motion is used to prevent surge – this can be achieved through venting for surge prevention or backflow for surge prevention~~

How should I understand the hs/ps parameter? It makes sense that a lower flow rate results in a value that is closer to the curve. But when the inlet pressure is high, this ratio also decreases, causing the value to be closer to the curve as well. At the same flow rate, will the compressor experience surge if the inlet pressure is too high?