The variable frequency air compressor realizes the dynamic matching of gas production and gas demand by intelligently adjusting the motor speed, and its unloading frequency reflects the operating efficiency of the system and the health state of the equipment. The following describes the criteria for determining the unloading cycle in terms of technical principles, influencing factors and optimization recommendations:
the Essence and Determination of 1. Unloading State
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unload Definition
when the gas consumption is lower than the minimum output of the equipment, the compressor enters the unloading state by closing the intake valve and maintaining low-speed operation, so as to avoid the impact of frequent start and stop on the power grid and equipment. -
Normal Unload Characteristics
- periodicity: In a continuous production scenario, the proportion of unloading time should be ≤ 30%, that is, the unloading time shall not exceed 3 minutes during every 10 minutes of operation.
- Instantaneous: The duration of a single unloading is usually 10-30 seconds, which is used to balance the pressure fluctuation of the pipe network.
2. Core Factors Affecting Offload Frequency
- fluctuation of gas consumption
- when the fluctuation range is more than 30%, the frequency conversion system needs to adjust the speed frequently, resulting in an increase in the number of unloading.
- Typical scene: due to the change of production rhythm in the welding workshop of the automobile factory, the gas consumption fluctuates periodically, and the unloading frequency can reach 15 times per hour.
- Matching degree of equipment selection
- when the rated gas production exceeds the maximum gas consumption by more than 20%, the equipment is in a low load state for a long time, and the unloading time accounts for> 40%.
- Selection suggestion: the maximum gas consumption should be controlled in the range of 70%-90% of the rated flow of the equipment.
- Gas tank volume configuration
- insufficient volume will lead to increased pressure fluctuations, forcing the compressor to start and stop frequently.
- Configuration standard: The volume of the gas storage tank shall be ≥ 50% of the total gas consumption per minute of all gas-using equipment.
Criteria for Abnormal Unloading of 3.
| Exception Type | phenomenon description | potential causes | disposal recommendations |
|---|---|---|---|
| frequent Uninstall | unload> 20 times per hour, single <10 seconds | leakage of used gas pipeline and too narrow pressure band setting | leak detection, broaden the pressure setting range |
| long-term unloading | continuous unloading> 5 minutes, loading time < 30% | excessive equipment selection and sharp reduction of gas consumption | add gas equipment and replace low-power models |
| unable to Unload | exhaust temperature due to continuous loading> 90℃ | control program failure, stuck solenoid valve | check PLC logic and replace faulty valve |
4. operation optimization strategy
- intelligent joint control system
- deploy the Internet of Things controller, realize the linkage scheduling of multiple compressors, automatically start and stop the equipment according to the gas demand, and reduce the unloading frequency by more than 40%.
- Pressure belt optimization
- widen the conventional 0.05MPa pressure band to 0. 1MPa reduce the number of unloading triggered by pressure fluctuations.
- Leak Management
- regularly conduct pipe network pressure holding test and repair> 0.5bar /min leakage point, can reduce the basic gas consumption by 10% -15%.
5. Maintenance Cycle Recommendations
| inspection Items | cycle | operation content |
|---|---|---|
| pressure sensor | quarterly | calibration accuracy, error> 1% to be replaced |
| solenoid valve | every half year | test response time,>0.5 seconds to be cleaned or replaced |
| PLC program | annually | optimize control logic and adapt to process changes |
the unloading period of the variable frequency air compressor shall be comprehensively determined in combination with the specific working conditions. Enterprises should establish a database of equipment operation, record key parameters such as unloading frequency and gas consumption, and identify abnormal conditions in advance through data analysis. For equipment with abnormal unloading frequency, it is recommended to entrust a professional team to carry out system diagnosis and formulate a targeted optimization plan.
