【作者】 刘峰；

【导师】 张齐生；

【作者基本信息】 燕山大学 ， 机械电子工程（专业学位）， 2017， 硕士

【摘要】 地球上有70.8%的面积被水所覆盖,但其中97.5%的水是海水,不能被直接利用,并且在其余2.5%的淡水中,能够被利用的淡水资源仅占地球总的水量的0.26%。因此,大力发展海水淡化技术,已经成为现代社会的当务之急。本论文就是基于能量回收的核心技术,应用电液比例换向阀通过双作用单活塞杆液压缸来对海水缸输出的海水进行压力闭环控制,同时,对未通过渗透膜的高压浓海水中的能量进行回收利用。由于海水中成分相当的复杂,所以渗透膜前的压力控制就会出现参数时变性、非线性等问题,而实际要求渗透膜前压力一定要稳定在7MPa,来保证渗透膜的使用寿命。因此,改善系统的性能,保证渗透膜前压力平稳成为本课题的主要研究目标。首先,分析了研究海水淡化液压系统的结构以及工作原理,它是通过压力传感器来检测反渗透膜前的海水压力,并将其信号反馈给比例换向阀,用电流信号控制阀芯的移动来保证液压缸输出稳定力,进而使海水缸输出压力稳定。随后,对液压系统中的各个环节进行数学建模,从而应用MATLAB软件进行系统的分析研究。其次,通过对系统的研究分析发现,控制系统需要控制器来调节系统,文中根据系统输出仿真曲线,建立了PID控制器和模糊PID控制器,比较发现模糊PID控制器具有更好的控制效果。然后,在实际的应用现场,通过电气系统及液压系统的安装调试,对实际的海水输出压力进行数据采集分析,表明本套海水淡化系统具有较好的控制效果,完全满足实际工艺的要求。最后,对论文及研究成果进行总结,并提出进一步的工作设想以及工作展望。更多还原

【Abstract】 There are 70.8% of the area of the earth is covered by water,but 97.5% of the water is seawater and can not be used directly,and in the remaining 2.5% of the fresh water,the amount of fresh water that can be used is only 0.26% of the total amount of t he earth’s water.Therefore,developing desalination technology has become a top priority of modern society.The core technology of this paper is based on the principle of energy recovery.And the electro-hydraulic proportional control technology is applied in the system.To control sea water cylinder output pressure,the double-acting single piston rod hydraulic cylinder is applied to pressure closed-loop control,at the same time,the high pressure concentrated seawater not penetrate the reverse osmosis membrane is recovered.Because the sea of composition is very complex,so the problem of membrane pressure control will appear the time-varying parameters,external load disturbance and nonlinearity etc.Base on the process requirements the pressure before the membrane must be stable,so as to ensure the life of desalination equipment.Therefore,improve the performance of the system,to ensure the smooth membrane pressure has become the main goal of this study.Firstly,the structure and working principle of the hydraulic system of seawater desalination are analyzed and studied.The pressure sensor is used to detect the seawater pressure before the reverse osmosis membrane to control the displacement of the valve core of electro hydraulic proportional directional valve,so as to make the hydraulic cylinder output force is stable.Then,the mathematical modeling of each link in the hydraulic system is carried out,and the MATLAB software is used to analyze the system.Secondly,through the analysis of the system analysis found that the control system requires a controller to adjust the system.In this paper,PID controller and fuzzy PID controller are established according to the system output simulation curve and It is found that the fuzzy PID controller has better control effect.Then,in the actual application site,through the electrical system and hydraulic system installation and commissioning,the actual seawater output pressure data acquisition and analysis,indicating that this set of desalination system has a good control effect,ful y meet the actual process requirements.At last,summary the paper and research results,and puts forward the further work ideas and work prospects.更多还原