Study And Design On The Gas Supply System In The Launch Area

The gas supply system in the launch area offers compressed air,high-purity nitrogen and high-purity helium for carrier rocket,spacecraft test,fueling and satellite launch, which is an important part of the ground service support system in the launch area. At present, the gas supply system is easily operated and controlled but not convenient for fault diagnosis and problem solving, and also not in favor of improving the reliability and safety of launch control because of lacking the working status and data from the automatic record equipment. Realizing automatic control and centralized monitor & control of the gas supply system will not only solve all kinds of problems and disadvantages under manual control at present, but also can be transplanted and extended to the monitor & control system of the equipment in other ground service support systems such as: low-voltage power distribution,cable arms,platform and air conditioning , which will finally become a part of the centralized monitor & control and telemetering launch system of the ground equipment.On the basis of analyzing the present situation and existing problems of the gas supply system in launch area, the thesis describes the general technical principles and parameters in the system designing and analyses the basic control functions the system should realize. And the thesis also shows the statistics of reference points in air,nitrogen and helium systems and related circuit diagram and pipe diagram. Then the thesis introduces the definition,functions and characteristics of programmable controller and the main factors which should be considered while choosing programmable controller. The thesis also gives an introduction about the general situation and technical essentials of PROFIBUS and the general situation of the use of AS-i master series connection between sensor and actuator.After the introduction of the selected elements, the thesis gives out a design which includes a front control center based on SIEMENS S7300 PLC,a line connection of the master PROFIBUS and the distributed intelligent I/O ET200M system,a real-time display system of pressure sensors and a gas supply system with stop valve and electric actuator. To the point of pressure sampling and control in the gases storage, considering the wide range of the distribution of gas vessels is not fit for parallel wiring, the design adopts the AS-i interface to realize series connection, and put which as a subnet of PROFIBUS. The telecontrol computers can connect optical fiberwith PLC through a special communication card, which could meet the needs of telecontrol in launch area.On the basis of general introduction of the definitions of reliability and reliable project and the basic method of reliability analysis of elements and system, the thesis analyses and calculates the reliability of the end gas distribution desk under both manual control and automatic control. The result proves that the automatic transform can actually improve the system reliability. After the analysis of the result, the thesis also gets an effective method to improve the reliability of the present gas supply system: using parallel output valve at the key point and reducing the use of stop valves at other points as far as possible to reduce the complexity and improve the reliability of the system. The method above also proves that the method of using too many parallel vessels and valves under manual control at present is not scientific. In a word, the research and realization of this thesis will fulfill the blank in the field of gas supply control system of domestic launch complexes and offer a practicable reference plan for the telemetry and telecontrol of the present equipment in the ground service support systems.