Study On Technical Economic Analysis Of CNG Refueling Station And Valve's Work Pocess In A Secondary Refueling Station's Compressor

With the rapid development of natural gas industry and the enhancement of urban environmental protection, natural gas vehicles, which are driven by natural gas other than gasoline and diesel oil, not only have preferable environment benefit, but also have some advantages such as abundant resource, better economy and run smoothly, etc. Therefore, natural gas vehicles are greatly developed in these years. On the other hand, the construction of compressed natural gas refueling station, as a key step of natural gas vehicles' industrialization, has been a hot focus. In this thesis, the natural gas vehicles refueling stations are analyzed from the technical and economic aspects. At the same time, the work characteristics of the secondary refueling station compressor's valve at a changed conditions and proper choice of the electromotor worked at short periodic time are also discussed. Various natural gas refueling stations are introduced in the thesis, and the makeup and work flow of standard refueling station are illustrated in detail.Moreover, various secondary refueling station and quick-fill system are analyzed, which provide groundwork to diversified development of refueling station. The primary design of refueling station is analyzed, and the volume choice of gas storage and compressor is introduced to a standard refueling station which offers ten thousand cubic meet per day. Moreover, the working principle of three-cascade filling system on above designed refueling station is analyzed by numerical simulation, and the influence to utilization ratio of gas cylinder group is discussed at different scale gas cylinder group and switch pressure difference between gas cylinder groups. The thesis also simulates the working process of refueling station in one day under the condition of having compressor direct-fill or not, and analyzes their traits. According to computation method of the flux in gas transporting pipeline, the formula of flux computation through the natural gas dispenser is derived, and the filling time of natural gas vehicles is computed primarily. The influence to filling time of pipe diameter and pipe length at forth and back of main airstreams valve is discussed, which provides the possibility that enhances the filling flux by choosing proper pipe diameter and length. After compared CNG standard refueling station with secondary refueling station from economic aspect, the economic area of CNG refueling station and secondary refueling station is obtained, and some factors affecting their economy are discussed such as the distance between secondary refueling station and primary refueling station, the volume of gas storage, etc. Furthermore, a new type of secondary refueling station is put forward, which works by use of the pressure difference between gas cylinder groups and vehicle cylinder instead of compressor, and is compared with typical secondary refueling station from economic facet. Farther, the possibility of practical use is analyzed. According to the work characteristics of secondary refueling station's compressor, the motion rule of the valve in high pressure stage is simulated by use of mathematical model. At the same time, the bounce velocity between valve plate and valve seat, the bounce velocity between valve plate and lift restrictor, the bounce between valve plate and spring are studied at different suction pressure. Based on these studies, it shows that the work characteristic of compressor valve will keep well under the change of suction pressure when the choice of valve parameter is reasonable, and advises that increasing the rigidity coefficient or decreasing lift properly will probably eliminate the delay-close phenomenon of the exhaust valve.