Air Compressor Control System
Air Compressor Control System
Compressed Air is essential tool that are used in a variety of industries. Some of these industries include the oil industry, the chemical processing plants, the pharmaceuticals industry, and the heavy industries. It is critical that these compressors operate at a high level of efficiency without any breakdowns, which is why a reliable and efficient control system is required.
Depending upon the types of compressors & compressor components there can be different type of control that can be used for a compressors including but not limited to auto dual or dual control, modulation or inlet valve modulation, constant speed, timer based, variable displacement etc.
Sensors and electrical components make up the control system. These components can all be controlled from one central point. The versatility and functionality of controllers have been enhanced by improvements in sensor technology and microprocessors.
Computerized control systems are more common in large compressors. They can perform several automatic functions.
We can break down the eight critical functions of compressor control systems, regardless of the technology used.
1. Starting and stopping the system in a safe manner
The operator performs preliminary preparations and checks during start-up. The valves are checked, auxiliary equipment is checked, and if necessary, purging is done. All stabilizers such as lubricants and coolants must be in good shape for the compressor to run smoothly.
A compressor and all its auxiliaries are monitored by sensors.
As it warms up, the compressor runs at a low speed while being carefully monitored. Gradually, the speed increases until the ramp speed is reached, which is the speed at which compression is the minimum. When the compressor reaches full speed, it performs at its peak.
Likewise, shutting down requires a lot of work. As its inlet supply is gradually reduced, the compressor slowly slows down. As the deceleration continues, the inlet supply is totally shut off. After a while, the compressor completely stops.
The compressor controls vary the speed of the compressor during these two processes. This ensures a safe and successful start-up and shutdown. Often, intelligent control systems can seamlessly implement these tasks by themselves or with little assistance from a human.
2. Provide information about the system
Sensor information can be used to determine the compressor’s status in real time. A low oil level, for instance, could indicate an oil leak. Insufficient lubrication or worn parts may cause high temperatures.
Among the most important sensors are:
Compressor control systems include sensor systems on auxiliary components. These sensors monitor environmental conditions outside the compressor. This information is essential to the compressor’s operation.
It is important to note that every compressor is rated for a specific working condition. Compressor efficiency can be reduced if certain variables are off from the optimum level. This results in a shorter lifecycle of the compressor and more energy consumption.
Using collected data, it is possible for the compressor’s parts to be observed for their wear rate. This can be used to prepare maintenance procedures and schedules.
3. Motor Control (Driver Control)
Electric motors are usually used to drive compressors. They are efficient, clean, and produce high torque. Motor controls are however required for electric motors. With motor controls, the motor is protected and its operational variables are controlled.
Pilot devices typically control motors. They are made up of switches and indicators. This allows the operator to operate the motor.
Devices such as these are typically used as part of a control system, automated process, or a control panel to provide information on the condition and control monitoring of different types of processes, machinery, and equipment.
A pushbutton controls the closure and reopening of contacts manually. The contact blocks of these devices are either normally closed, normally open, or a combination of both.
Pilot lights – These devices give visual feedback about the status of a circuit. Their primary purpose is to indicate ON/OFF, changing conditions, and alarm signaling.
Short circuits, surges, overloads, and surge protection are all provided by circuit breakers.
MCBs are used to handle currents below 100 amps.
Relays are controlled switches that respond to external signals. High-power circuits are controlled by relays.
Monitoring and adjusting the power output of the motor is done with intelligent devices. Motor variables such as torque and speed are automatically adjusted to match the load. As a result, there is low power consumption, low noise, low vibration, and little radiant heat.
PLCs are used for automating these processes. A Human-Machine Interface (HMI) provides communication between the motor and control devices and the operator.
HMI stands for human-machine interface. Intelligent motor controls allow the operator to interact with the motor.
Power and speed of the compressor are controlled by the driver. The speed can be varied with some compressors. Compression is most effective within this range.
It is possible to vary the pressure or gas output in such a case by altering the speed of the driver. Positive displacement rotary compressors have a direct correlation between the rotation speed of the input shaft and the displacement of the compressor.
Variations in the speed of the driver affect the compressor’s output. If the compressor output must fluctuate frequently, this feature is useful. A VSD compressor i.e rotary screw compressor with variable speed drive is used as one of the popular method of compressor capacity control method in the industry.
Reduced drive speed, however, decreases compressor efficiency. It is necessary to change other variables along with the drive speed. This maintains efficiency within reasonable bounds.
Driver output can be adjusted by the air compressor control systems. In addition, the motor’s load and temperature are adjusted to ensure that it does not become overloaded or overheated. For efficient operation, the motor controller balances the torque, power, and speed outputs of the motor.
4. Maintain stable compressor operation
Stability with compressors refers to the RPM, gas input, and output being optimal and stable. Choke and surge are two of the most common undesirable conditions experienced by compressor controls. When they occur, the compressor becomes unstable.
During a surge, the input gas supply is below its optimal level. The drive motor becomes overloaded. During this process, the compressor seeks to pull in more gas while pushing out more.
As a result, output fluctuates, power usage is irregular, and vibration and noise are increased. Many compressors automatically offload when their inlet capacity drops below 40%.
Occasionally, the reduced gas intake cannot be matched by adjusting the driver’s speed. In such cases, the surge control must stabilize the compressor. Most compressors are equipped with surge control. An automatic valve controls this gas path. It links the inlet system with the output system.
Whenever a drop in gas supply is noted, the valve connecting the outlet pipe to the inlet pipe is opened. As part of the process of increasing the input volume, some of the output gas is injected into the inlet. The valve closes once normal gas flow is restored from the original gas source. Operation returns to normal.
By reversing the flow, the problem of surges is solved. However, the overall compressor throughput is decreased as well.
The opposite of surge is choking. It is caused by a very high input flow rate at the input of a compressor operating at a low discharge pressure.
As a result of choking, the compressor’s performance is drastically reduced. Pressure and flow cannot be delivered at optimal levels by the compressor.
Inlet controls automatically restrict the system by closing a portion of the inlet valve. If gas is compressed or accelerated at the inlet, this limits the capacity and efficiency. In such a case, choke controls can divert excess gas into low-pressure buffer storage so that the gas does not reach the inlet.
5. Manage Process Variables to Desired Values
Controlling the requirements of the compressor is the responsibility of the compressor control system. A lot more goes into executing and adhering to the commands than what appears to be a simple matter of flipping switches or interacting with an HMI.
Compressor output must meet expectations. It is the controller’s responsibility to ensure this is always the case.
The control system can modulate the inlet valve in addition to adjusting the drive speed to control the flow rate and displacement of a compressor. Gas intake is throttled by modulating the intake valve to maintain a certain pressure.
When the incoming gas capacity decreases, the pressure and amount of gas at the output also decreases. The compressor draws a vacuum at the inlet if the inlet supply is cut off at full speed. This may result in motor overload and overheating.
Using the modulating controls, the motor controls are adjusted to prevent this. The inlet pressure is reduced as well.
Compressors operate with a partial load most of the time. Because of this, displacement can be adjusted without engaging the driver controls.
7. Auto-shutdown in unsafe conditions
Compressors have low fault tolerance for the majority of their components. Sensors monitor the status of key components. It is possible to prevent damage if anything goes wrong by taking drastic measures in advance.
An automatic shutdown can be initiated by compressor control systems. It usually occurs when a vital component fails or if unsafe working conditions exist. Uncontrolled surges and chokes, or overloads of the electrical systems, are hazardous conditions.
8. Multiple controls for compressors
Controls are linked together to form network controls in industries that need more than one compressor. One compressor assumes the role of the master and the others take on the functions of subordinates. The whole system is controlled by a master controller rather than individual compressor controls to control full load & part load operations.
Data and commands are shared among sophisticated networked controls. The entire system is controlled by one central processor acting as master control emplying various control strategies. Performance and output variables are maintained as desired in tight pressure band thus controlling pressure drops due to leaks.
Utilizing Compressor Control
Compressor variables are controlled by air compressor controls systems. By keeping them in good working order, the compressor will perform at its best. The purpose of these components is to ensure efficiency, energy savings, increased system performance and safety.
There are various type of compressor. They are available in a wide range of models, sizes, and performance levels. They are all, however, incomplete without dependable controls.
We at Turbo Airtech do more than just work with OEM control panels. We also design and manufacture essential control systems with PLCs and SCADAs.