| Reciprocating compressors are widely used in industry. It's really important to realize stepless capacity regulation for reciprocating compressor. The stepless capacity regulation method by depressing the suction valve makes the inhalational intake gas back to suction chamber during partial compression stroke, only the required gas is compressed. By this method, compressor capacity can be regulated steplessly in a range between 0-100%and the power consumption is saved proportionally with capacity. By now, the similar capacity regulation system of reciprocating cpmpressor developed by Hoerbiger has been widely used in the world, but it is difficult to be popularized in domestic industry for the high price and reliability limitation. It is still the major research interest for the other international compressor valve companies (eg. COOK) to study the stepless capacity regulation facility since relevant projects have been reported. Therefore, it is great need to develop the stepless capacity regulation system, which conforms national conditions of our country and has independent intellectual property rights.Based on the National Key Technology R&D Program "Key Technology Development Program for High Efficiency Compressor" (No.2008BAF34B13), and Doctoral Fund Project from Education Department "Research on Valve Dynamic in case of Reflow situation for Variable Mass Compressor System", the thermal cycle and valve dynamic in the case of stepless capacity regulation are deeply studied by theroy and experiment in this dissertation, the key techonolgy and equipment for the 10～100% capacity regulation system are also developed. The field tests show that this stepless capacity regulation equipement possesses smooth operation and significant energy savings.The main researche topics in this dissertation are as follows:1. A theoretical thermal cycle model in case of stepless capacity regulation has been developed. Capacity variation with the unloader crankangle has been calculated. The calculation result is in accordance with experiments.2. The valve dynamic model in case of stepless capacity regulation has been established. The valve dynamic differentical equations based on real gas state equation and ideal gas state equation respectively in stepless capacity regulation are derived in this dessisation. Valve plate dynamic motion in stepless capacity regulation has been revealed through computer calculation and experiment.3. Multiple freedrom motion model for compressor valve in the case of stepless capacity regulation has been developed. The valve plate motions under normal operating condition and stepless capacity regulation condition are calculated respectivly and compared. The calculation results show that the unloader in stepless capacity regulation makes valve plate incline impact velocity reduced obviously.4. A control system used in stepless capacity regulation system has been designed. A method to keep the rotating speed and phase synchronization between the compressor motor and hydraulic distributor has been proposed. System framework, which uses the upper computer to control the operation of reciprocating compressor and uses the lower computer to control the stepless capacity regulation system, is constructed. The multiple stage control strategy of reciprocating compressor in stepless capacity regulation has also been proposed in this dissertation.5. The stepless capacity regulation system, which is suitable for explosive gas zone has been developed, which has been successfully applied on large-scale industry reciprocating compressor in Zhenhai Refining & Chemical Company(ZRCC).6. By using the finite element analysis tool, the impact process between the unloader and valve plate has been demonstrated in the case of stepless capacity regulation situation. The influence factors for the maximum stress in the valve, which are generated by valve assemble errors, unloader material or unloader mass and so on have been evaluated.
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