What is Anti Surge System? Purpose, Types, Advantages, and Disadvantages
In a centrifugal compressor, to maintain its speed at required, there is a certain capacity below which the operation is unstable. This breakdown point is called “Surge”.
Surge is a term associated with low flow.
It is the phenomena, resulting from the inability of the turbo compressor impeller to produce the amount of required energy that the process system requires.
Surge is an inherent phenomenon in centrifugal compressors, which can damage the machine. The intensity of surge varies from application to application and proportional to the density of the fluid.
Surge is a high-speed phenomenon, surge flow reversals can occur in less than 150 milliseconds. Pressure rapidly fluctuates, noise is generated. Temperature increases can be very rapid and mechanical damage can occur.
The anti-surge control system is designed to determine the surge condition in the compressor and to operate the anti-surge control valve in an efficient and speedy manner to protect the centrifugal compressor from the surge.
The quickest way to eliminate surge is to rapidly reduce the pressure buildup by opening a blow-off or recycle valve in the discharge system to maintain the required flow.
Blow off causes waste of expensive process fluid, therefore, recycle is preferred and mostly carried out by through 4-20 mA electronic operated control valve which is termed as “Anti-surge Control Valve”.
The anti-surge control controller (UIC) provides the compressor against the surge by opening the recycle valve.
Opening the recycle valve lowers the resistance felt by the compressor.
The anti-surge controller imaginary operation protection line is Surge Control LIne.The anti-surge system has to control the operating (OP) point on the right of SCL. If OP is moving leftward toward SCL, your algorithm shall open Anti-Surge Valve (ASV).
In the advanced controller, the control action is split into two actions.
PI action is dealt with small and steady-state disturbances while recycling trip action will cope with sudden and quick process disturbances as shown in the below figure. Two lines are introduced right to SLL for this control algorithm.
Surge control line (SCL) and surge trip line as shown in the below figure.
PI action will be initiated when the operating point touches the SCL line and RTL action will be initiated when the output line touches the RTL line. RTL generates a step opening response until output returns to the safe area.
Total Response = PI Control response and Recycle Trip response.
Please note that the derivative action is separate from the derivative action of the normal PID controller as this D action is only concerned with the opening of the control valve, whereas in PID controller derivative action takes part in both opening and closing the valve.
Also Read: Types of Anti Surge Control based on Process
Electrical Drives control the motion of electric motors. Motion control is required in industrial and…
PLC ladder logic design to control 3 motors with toggle switch and explain the program…
VFD simulator download: Master the online tool from the Yaskawa V1000 & programming software for…
The conveyor sorting machine is widely used in the packing industries using the PLC program…
Learn the example of flip-flop PLC program for lamps application using the ladder logic to…
In this article, you will learn the STAR DELTA programming using PLC controller to start…
View Comments
Actually what is the reasons for surge what is the use of scrubber
1. To protect the compressor we recycle the part of discharge flow to suction to maintain the minimum suction requirement. It avoid the tripping of compressor and mechanical damage also.
2. The use of scrubber is to avoid the fluctuations in the fluid flow to the suction to compressor.