| Steam is one of the most useful and clean sources of energy for the modern industry, providing strong power for production facilities. However, the water drop in the wet steam may at the same time corrode the facilities, threatening the security of operation and affecting the efficiency and proceeds. Due to these reasons, researches on Wetness On-line Measurement technology for wet steam have great importance and significance.In order to satisfy the demand of high precision and real time, I propose and design an online measurement system based on de Laval nozzle, which is a creative breakthrough in steam humidity measurement.I give a detailed explanation of the theory in the thesis and design and construct an online steam humidity measurement system. Given the steam with standard humidity, I build the marking unit to mark the experiment result and increase the system precision. In addition, I applied the Fuzzy PID Control Technique to design and optimize the system control, ensuring the system operation on the right track.The thesis is divided into four parts:Part1, I summarize the significance of steam humidity online measurement and the international research progress, conclude the theory, feature and limitation of the traditional measurement methods and put forward the online measurement system based on de Laval nozzle.Part2, I interpret the theory of my designed system, whose formula is deducted by a mass of other formulas based on the Law of conservation of mass. I also give the method to measure the velocity of sound in two mixed gases. I design and construct the online measurement system(trial version) based on de Laval nozzle, including de Laval nozzle, condenser, metering pump and data collection and process module. Through Fluent, I prove that under experiment condition, de Laval nozzle can be in the working status. I also complete the device selection, structure designation and system debugging to realize basic function. I briefly introduce the importance of the highly effective control method in online steam humidity measurement system. I also do research on how to implement the PID Control Technique as well as the implementation of PWM pulse-duration modulation technology in DC electro-motor’s speed governing system Part3, I design a standard equipment on marking experiment of steam humidity online measurement system, attached with the equipment theory, component structure and the construction and interpret the high-dispersion nozzle including the fog-making principle and marking equipment usage. I conduct a marking experiment of steam humidity online measurement system and do the factor analysis which proves the correctness of my system.Part4,I bundle the research work and put forward the future research direction and goal. |
