Study on Key Techniques of Supercritical Carbon Dioxide Compressor

Carbon dioxide is one of gases that receive much attention and interest, not only because it is the largest contributor to the greenhouse effect, but also because it is widely used in some industries such as Petroleum and chemical industry, automobiles, ships, aviation, space for the specific properties and performance under specific conditions. Supercritical carbon dioxide is one of very good medium which have many unique properties and be used in the extraction process, refrigeration, etc.High pressure and special property of Supercritical carbon dioxide bring more uncertainty to the Supercritical carbon dioxide centrifugal compressor than other kind of normal centrifugal gas compressor, resulting in frequent occurrences of failures. Reasons that cause failures mainly includes two aspects:1) The residual axial force is so big that lead to the rotor thrust bearing bushing temperature too high or even burning out2) The air flow excitation causes rotor instability.Based on the reasons above, this paper’s main work and contributions are as follows:1) Establishing the whole full port model of a centrifugal compressor the model combines the compressor mainstream basin and flow field in the gap on the rotor and sealing. And then, calculation and analysis using CFD technology are carried out to have an insight into all the details of internal flow field in the compressor. Combination of primary flow and secondary flow analysis can be more realistic to situation. This method can help the design personnel have a direct observation of internal flow field of centrifugal compressor, and then can study the influence of the flow field caused by changes in the structure, so that they can make the design more accurate. 2) Researching the uncertainty of compressor axial thrust based on full port simulation technique by CFD, the whole of a centrifugal compressor stage axial thrust is studied. Analysis the axial thrust of centrifugal compressor rotor at different inlet pressure, seal clearance, and different work mass flow changes. Accurate grasp of thrust force can effectively avoid the centrifugal compressor failure caused by excessive axial thrust bearing, etc. And then, study the effect of air flow excitation to the performance based on this model at the different operating conditions,3) In view of the actual high pressure large flow rate of CO2compressor, analysis pneumatic performance and study the real gas the properties influence the to the compressor performance prediction and the axial thrust, etc.The research of this article is to explore a more accurate method for simulation of centrifugal compressor. And, research the influent factors of centrifugal compressor performance and parameter based on this method. The objective of the study is to provide theoretical basis for accurate predicting the performance of supercritical carbon dioxide compressor.