發(fā)布時間：2018-05-05 04:14

  本文選題：超臨界萃取 + 流量補償　； 參考：《長春工業(yè)大學》2015年碩士論文

【摘要】：超臨界萃取技術(shù)起源于七十年代末,是一種物質(zhì)分離精制的新技術(shù),它與傳統(tǒng)的萃取方式相比有萃取率高,無殘留,可以根據(jù)沸點高低的順序把成分先后萃取出來等優(yōu)點。還可以萃取很多具有特殊化學特性的物質(zhì),是一種綠色環(huán)保的萃取手段。本文以HA221-40-11型超臨界萃取裝置為研究對象,萃取釜內(nèi)的壓力和溫度決定著萃取過程是否處于超臨界狀態(tài),因而萃取壓力和溫度的動靜態(tài)性能指標直接決定著萃取率的高低,所以有必要精確的控制萃取壓力。在注入二氧化碳時,增壓泵全速運轉(zhuǎn),會造成壓力的超調(diào),由于本實驗設(shè)備的超調(diào)是不可逆的,所以我們需要引入流量控制,使萃取壓力性能指標時刻處于最優(yōu)狀態(tài),為此有必要引入流量控制內(nèi)環(huán)。通過分析其特點以及工藝控制流程特點,總結(jié)并研究了影響超臨界萃取劑輸送流量補償控制的諸多因素：溫度,壓力,進料量,流量,泵產(chǎn)生的多余熱量等等。這些參數(shù)都具有非線性和時變性等特點,為了達到提高萃取率的目的,對流量補償控制系統(tǒng)提出了更高的要求。根據(jù)控制要求,制定了溫度、壓力、流量的控制方案,重點研究了流量補償控制系統(tǒng),對萃取劑補償系統(tǒng)控制對象建立數(shù)學模型,根據(jù)萃取劑流量補償?shù)目刂埔?應用內(nèi)�？刂评碚撛O(shè)計了前饋—IMC控制器,利用MATLAB/SIMULINK對前饋—工MC控制器進行仿真驗證。接著分別對前饋—工MC控制器和IMC控制器進行仿真,對比二者的仿真曲線,證明了前饋—IMC控制器可以提高控制精度,提高萃取率。其次,本文應用改造后的超臨界萃取設(shè)備進行萃取實驗,在同樣的實驗條件下,將得到的實驗數(shù)據(jù)與之前未經(jīng)改造的設(shè)備萃取實驗的數(shù)據(jù)進行對比,結(jié)果表明,經(jīng)改造后的實驗設(shè)備的萃取率有了較大的提高,驗證了超臨界萃取流量補償控制系統(tǒng)的控制效果。最后,設(shè)計了基于PLC的萃取釜溶劑輸送流量補償控制系統(tǒng),上位機由研華工控機以及觸摸屏組成,下位機由西門子S7-300系列,執(zhí)行單元以及傳感器組成,利用組態(tài)軟件MCGS完成上位機觸摸屏和PLC的監(jiān)控組態(tài)的設(shè)計,實現(xiàn)了監(jiān)控流量、溫度、轉(zhuǎn)速、壓力等控制和參數(shù)設(shè)置、證書信息添加、查詢,打印等功能。研究結(jié)果表明,該超臨界萃取釜溶劑輸送流量補償控制系統(tǒng)具有萃取率高、能耗低、控制精度高等特點,達到了設(shè)計要求,為萃取釜溶劑流量的精確控制和補償提供了一種有效的方法。
[Abstract]:Supercritical extraction (SFE), which originated in the late 1970s, is a new technique for separation and purification of substances. Compared with the traditional extraction method, it has the advantages of high extraction rate and no residue, and it can be extracted successively according to the order of boiling point. It can also extract many substances with special chemical properties. It is a green extraction method. In this paper, HA221-40-11 supercritical extraction device is used as the research object. The pressure and temperature in the autoclave determine whether the extraction process is in the supercritical state or not, so the dynamic and dynamic performance indexes of the extraction pressure and temperature directly determine the extraction rate. Therefore, it is necessary to accurately control the extraction pressure. When carbon dioxide is injected, the pressure overshoot will be caused by the full speed operation of the booster pump. Since the overshoot of the experimental equipment is irreversible, we need to introduce flow control to make the extraction pressure performance index in the optimal state at all times. Therefore, it is necessary to introduce the inner loop of flow control. Based on the analysis of its characteristics and the characteristics of the process control process, the factors affecting the flow compensation control of supercritical extractant transportation are summarized and studied, such as temperature, pressure, feed volume, flow rate, excess heat produced by pump, and so on. These parameters are nonlinear and time-varying. In order to improve the extraction rate, a higher demand is put forward for the flow compensation control system. According to the control requirements, the control scheme of temperature, pressure and flow rate is formulated. The flow compensation control system is studied emphatically. The mathematical model of the control object of the extractant compensation system is established, and according to the control requirements of the extractant flow compensation, The feedforward-IMC controller is designed by using the theory of internal model control. The simulation of the feedforward MC controller is carried out by using MATLAB/SIMULINK. Then the feedforward MC controller and IMC controller are simulated, and the simulation curves are compared. It is proved that the feedforward controller can improve the control precision and the extraction rate. Secondly, the experiment was carried out by using the modified supercritical extraction equipment. Under the same experimental conditions, the obtained experimental data were compared with those of the previous unmodified equipment. The results show that, After modification, the extraction rate of the experimental equipment has been greatly improved, which verifies the control effect of the supercritical extraction flow compensation control system. Finally, a solvent conveying flow compensation control system based on PLC is designed. The upper computer is composed of the industrial control computer and touch screen, and the lower computer is composed of Siemens S7-300 series, executive unit and sensor. The configuration software MCGS is used to design the monitoring configuration of the upper computer touch screen and PLC. The functions of monitoring flow, temperature, speed, pressure and parameter setting, certificate information adding, query, printing and so on are realized. The research results show that the system has the characteristics of high extraction rate, low energy consumption and high control precision, and meets the design requirements. It provides an effective method for accurate control and compensation of solvent flow in extractor.
【學位授予單位】：長春工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TQ028.32;TP273

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