Two parallel operation scheme of air compressor

Two parallel operation scheme of air compressor the aim is to achieve stable gas supply, load balancing and energy-saving operation through the cooperative work of two air compressors. The core points are as follows:

core objectives of 1. parallel operation

1. stable gas supply: Two air compressors are operated with one operation and one standby or alternately to avoid interruption of gas supply caused by single failure and ensure production continuity.
2. load balancing: Dynamically adjust the operating status of the two air compressors according to the gas demand to avoid problems such as excessive exhaust temperature and accelerated component wear caused by long-term full-load operation of a single air compressor.
3. energy saving and consumption reduction: Reduce frequent start and stop of air compressor through intelligent control, reduce energy consumption and extend equipment life.

2. hardware configuration and installation requirements

1. equipment selection:
   • the two air compressors need to have the same pressure parameters (such as exhaust pressure, flow range) to ensure that the performance matches when working together.
   • The screw air compressor is preferred, which has stable operation and low maintenance cost, and is suitable for parallel operation.
2. Gas tank configuration:
   • A common air tank must be installed, and the capacity must be designed according to the total air consumption (such as 3m & sup3 in the factory case; the air tank meets the requirements of two air compressors).
   • The gas storage tank should be far away from the machine room (recommended distance of 12~15 meters, at least not less than 2 meters) to reduce the impact of vibration and noise.
3. Piping and Valves:
   • A check valve shall be installed between each air compressor and the air storage tank to prevent the compressed air from flowing backwards.
   • Gate valve shall be set on the exhaust pipe to facilitate maintenance and overhaul.
   • The outlet pipeline of the gas tank shall be equipped with a pressure regulating valve to stabilize the output pressure.

3. Control Logic and Automation Design

1. pressure switch grading control:
   • low voltage start: When the pressure of the air storage tank drops to the lower limit of the working pressure (such as 0.63MPa), start the working air compressor.
   • HV shutdown: When the pressure rises to the upper limit of the working pressure (such as 0.72MPa), the working air compressor stops.
   • Alternate startup: If the pressure continues to drop to the lower limit (such as 0.60MPa), start the standby air compressor; after the pressure is restored, the standby machine will stop.
   • Pressure alarm: When the pressure exceeds the upper limit or is lower than the alarm setting value (such as 0.50MPa), a fault signal is issued.
2. Intelligent rotation and load balancing:
   • through the PLC or centralized control system to achieve two air compressor automatic rotation operation, to avoid a single long-term operation.
   • Dynamically adjust the number of operating units according to the gas consumption (such as one for standby or two for simultaneous operation) to ensure load balance.
3. Delay and disable function:
   • after the standby machine is started, a time delay relay is set to avoid frequent start and stop.
   • It is forbidden to restart immediately after shutdown to prevent mechanical failure (such as restart when the rotor is not completely stationary).

4. maintenance and optimization measures

1. regular drainage and leakage prevention:
   • an electric drain valve is installed at the bottom of the gas tank to drain water regularly (for example, every 50 minutes and 2 minutes in rainy season).
   • Replace with zero-loss drainer to avoid waste of compressed air.
2. Air pressure monitoring and alarm:
   • air pressure alarm shall be installed at key positions in the workshop to monitor the pressure value in real time and give an alarm when it is lower than the set value (such as 0.50MPa).
3. Energy consumption optimization:
   • reduce the set value of air pressure (e. g. from 0.70MPa to 0.61MPa) and reduce air consumption (air pressure is reduced by 10% and air consumption is reduced by about 15%).
   • Use electric diaphragm pump instead of pneumatic diaphragm pump to improve energy efficiency.

5. case reference and effect verification

1. factory renovation case:
   • A factory runs two air compressors in parallel to meet the production demand (maximum air consumption 8.1m & sup3;/min, close to 45KW air compressor maximum displacement 8.6m & sup3;/min).
   • Air pressure stability is improved: the workshop air pressure is stabilized from 0.65MPa to 0.60MPa, and the shutdown accident caused by air pressure fluctuation is reduced to 0.
   • The energy-saving effect is remarkable: the 45KW air compressor only uses 70% of the flow, and the 37kw air compressor is on standby for a long time, saving electricity.
2. Application case of hydropower station:
   • two brake air compressor joint operation, through the pressure switch classification control, to achieve automatic start and stop and load balance, to ensure the stable operation of the braking system.