| The technology of Supercritical fluid extraction originated in the late seventy,it is a new physical separation refining technology,compared with traditional extraction methods, it has high extraction rate, no residue, can the composition according to the boiling point of order has been extracted,for the nonpolar and weak polar material,it has high extraction ability,it is good for heat transfer and energy conservation.This article first introduced the thesis research the source and the research significance, then introduces the present situation and trend of development of the supercritical fluid extraction technology in China and abroad.I made HA221-40-11 supercritical extraction device as the research object and analyses its characteristics and process control process,I summarize and study the influence of supercritical extraction agent conveying flow compensation control of many factors:temperature, pressure, feed rate, flow rate, the excess heat generated by pump, supercritical CO2 extraction solvent gasification, and so on.The characteristics of these parameters are nonlinear and time-varying,in order to achieve the purpose of improving extraction rate, puts forward higher requirements on flow compensation control system. According to control requirements, I make the temperature,pressure,flow rate control scheme,the mainly study is Flow compensation control system, the control object to establish mathematical model, extracting agent compensation system based on internal model control theory and the extracting agent flow compensation control requirements, design the feedforward and IMC controller, the controller to make use of MATLAB/SIMULINK simulation, according to the simulation results to determine the parameters of the low pass filter, then respectively for IMC controller and the feedforward-IMC controller are compared, and the simulation show that the controller can improve the control precision, then improve the extraction rate.Secondly,I make the experiments under the same experimental conditions with the supercritical fluid extraction equipment, I comparise the experiment data and without the transformation of equipment before extraction experiment data, the results showed that the modified experiments can markedly improved the extraction rate of equipment and to verify the effectiveness of the supercritical fluid extraction flow compensation control system control effect.Finally,I design the solvent extraction kettle conveying flow compensation based on PLC control system, the upper machine are computer and touch screen, the machine made by Siemens S7-300 series, execution unit and sensors, using the configuration software MCGS complete PC touch screen and PLC monitoring configuration, realize the monitoring such as flow, temperature, speed, pressure control and alarm function, parameter setting, certificate information add/query/printing, etc. The research results show that the supercritical extraction kettle solvent conveying flow compensation control system has high extraction rate, low energy consumption, high control precision, etc, has reached the design requirements, precise control and compensation for the solvent extraction kettle provides an effective method. |
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