Capacity adjustment control method of multi-head screw compressor

Abstract

The invention provides a capacity adjusting control method of a multi-nose screw compressor. The capacity adjusting control method solves the problem that the existing multi-nose screw compressor unit in an operation mode is poor in lubrication. The capacity adjusting control method of the multi-nose screw compressor comprises the following steps of 1, starting up and judging whether loading is required; 2, detecting the running time of each compressor before the loading; 3, loading the compressor with the shortest running time; 4, loading the compressor with the second shortest running time; 5, loading gradually and sequentially till the load requirement is met; 6, judging whether unloading is required; 7, detecting the running time of each compressor before the unloading; 8, unloading the compressor with the longest running time; 9, unloading the compressor with the second shortest running time; and 10, unloading gradually and sequentially till the load requirement is met. According to the capacity adjusting control method, for a condition that poor lubrication can occur when the compressor runs in a partial load state for a long time, a controller controls each compressor to act sequentially and adjacently according to the running time, so that oil return of the compressor is good, and the operation quality of the compressor can be improved.

Description

technical field [0001] The invention relates to equipment with multiple compressor units, in particular to a method for adjusting and controlling the capacity of multi-head screw compressors. Background technique [0002] Most of the screw compressors used in the market are in the form of segmented capacity adjustment, that is, in addition to the start-up capacity level, there are three capacity levels available. In the use of multi-head screw units, in the process of changing the load, the compressor will run at 50% or 75% of the load during the loading or unloading process, which is the partial load maintenance area. [0003] At present, the energy adjustment control of most multi-head screw units is balanced start. First, the running time of the compressor is detected, and the compressor with the shortest running time is started, and the compressors are arranged in sequence. After all compressors start at 25% (starting capacity level), all compressors start at 50% (parti...

AI Technical Summary

Problems solved by technology

[0004] When the indoor load is small, it is bound to cause the compressor to run under partial load for a long time. If it stays in this state (partial load) for a long time, the exhaust volume will decrease, and the refrigerant flow into the evaporator will decrease. Correspondingly, the flow rate of the refrigerant under the suction effect of the compressor decreases, resulting in a decrease in the amount of refrigerant oil returned to the compressor along with the superheated gas of the refrigerant. Long-term operation will cause the internal lubricating oil level of the compressor to decrease, resulting in poor lubrication of the compressor.

And the running time of the compressor at 25% (starting capacity level) should not be too long, that is, generally within 30S, if the time is too long, the oil return of the above compressors will decrease and the lubrication will be poor

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