Technical Research On In-situ Detection For Deep-sea Hydrothermal Fluid And Its Integration Of Prototype System

The dissertation has carried out the research on in-situ detections of temperature and pH value for deep-sea hydrothermal fluid, and therefore an in-situ multipoint temperature measurement system and a long-term in-situ pH value detection system for deep-sea hydrothermal fluid have been developed respectively. In-situ multipoint temperature measurement system has nine temperature measurement channels, which can acquire the temperature parameter during the form of hydrothermal chimney; long-term in-situ pH value detection system has self-calibration function of pH detection electrode, which can implement long-term in-situ pH value detection for deep-sea hydrothermal fluid. Owing to pH detection electrode can not implement long-time pH value detection in deep-sea hydrothermal fluid environment, the technical measures of implementing self-calibration of pH detection electrode using deep-sea fluid control technology has been put forward in the dissertation. In order to solve high pressure-resisting problem in deep-sea fluid control technology, a kind of fluid control system which could adapt the pressure variety in deep-sea high pressure environment was designed using pressure compensation method, thus, a firm technical support has been offered for implementing long-term in-situ pH value detection for deep-sea hydrothermal fluid. For the implement process of two in-situ detection systems for deep-sea hydrothermal fluid, technologies of mechatronic integration about two systems have been studied comprehensively, in which, the detector development of pH value detection for deep-sea hydrothermal fluid has solved the fluid change problem in the process of self-calibration of pH detection electrode. In order to validate the reliability of two in-situ detection systems, finally, sea tirals of two systems have been introduced.The main content of this dissertation is divided into six chapters:The first chapter has introduced several detection ways about deep-sea hydrothermal fluid activities by means of introducing the general research situation on hydrothermal mineralization, hydrothermal plumes and hydrothermal communities on the basis of lots of domestic and foreign literatures and references, in which, characteristic, content, present state and key technology about in-situ detection for deep-sea hydrothermal fluid have been especially introduced. Finally, the purpose, significance and main content of the research have been put forward.The second chapter has analyzed the detection principles of in-situ multipoint temperature measurement system and long-term in-situ pH value detection system for deep-sea hydrothermal fluid, and the cold-junction compensation principle of thermocouple and self-calibration principle of pH detection electrode have been introduced emphatically, and on the basis, the technical measures of implementing self-calibration of pH detection electrode using deep-sea fluid control technology has been put forward.The third chapter has studied in theory and experiment the fluid control technologies of long-term in-situ pH value detection system for deep-sea hydrothermal fluid. A kind of fluid control system which could adapt the pressure variety in deep-sea high pressure environment was designed using pressure compensation method, and it solves the high pressure-resisting problem in deep-sea fluid control technology. Considering the actual process during falling and rising in seawater, the fluid control system was protected by check valves. In order to know the dynamic performance of the fluid control system, using the method of power bond graph, the mathematic model was built and the simulation was done, and the simulation results indicate as following: the fluid control system can not be applied infinitely in high pressure environment even if the pressure equilibrium can be built through the way of pressure compensation, moreover, the system will vibrate when draining. In order to validate the reliability of pressure compensation of the fluid control system, the qualitative pressure experiments of the fluid control system were performed from easiness to complexity, and the experiment results indicate that the fluid control system can be applied in high pressure environment, in addition, the protect means of check valve is reliable.The fourth chapter has comprehensively studied the technologies of mechatronic integration about two in-situ detection systems for deep-sea hydrothermal fluid, including energy supply technology, control technology, encapsulation technology, detector technology, and data acquisition technology and so on. In the energy supply technology, a kind of energy supply equipment which was composed of seventy batteries was developed, and its discharge capacity was tested, and the test result indicates the equipment can supply more two months energy for the system. In control technology, the main control circuit and corresponding software of in-situ pH value detection system for deep-sea hydrothermal fluid were developed, and the combination experiment was performed, and the experiment results manifest that the main control system can implement prospective functions. In encapsulation technology, some common problems about encapsulation technology of deep-sea mechatronic equipment were discussed, and the design regulation about deep-sea high pressure vessel was presented. In detector technology, in order to solve the fluid change problem in the process of self-calibration of pH detection electrode, the pH detection chamber of long-term in-situ pH value detection system for deep-sea hydrothermal fluid was designed by means of structure parameter simulation, and the fluid change effect was tested, and the test results show that the pH detection chamber has very good fluid change effect, thus, some valuable experiences can be offered for the detector development of involving the fluid change process in deep-sea hydrothermal fluid detection. In data acquisition technology, the forward measurement channels for pH and temperature detection were discussed.The fifth chapter has introduced firstly the sea trial experiment of in-situ multipoint temperature measurement system for deep-sea hydrothermal, and the experiment results indicate that the technologies of mechatronic integration of the system are reliable. Plenty of temperature data are acquired in the sea trial, which provide original data for further scientific research. Secondly, the chapter has introduced in detail the pressure experiment of in-situ pH value detection system for deep-sea hydrothermal fluid, and the results show that the deep-sea fluid control system developed in the dissertation and all technologies of mechatronic integration adopted in the system go through the high pressure test, and this provides a firm basis for sea trial of the system. Finally, the chapter has introduced the sea trial experiment of long-term in-situ pH value detection system for deep-sea hydrothermal fluid, and plenty of valuable data are also acquired in the sea trial, and this indicates again the system has higher reliability.The sixth chapter has summarized the content of the dissertation, and puts forward some advices for further research.