發(fā)布時(shí)間：2018-05-20 20:50

  本文選題：三效蒸發(fā)器 + 一效二次蒸汽流量�。� 參考：《廣西師范大學(xué)》2017年碩士論文

【摘要】：在食品、制藥及化工等工業(yè)生產(chǎn)中,以生蒸汽為熱源的蒸發(fā)器被廣泛應(yīng)用于原料液的濃縮工藝中。早期這種蒸發(fā)器通常為能耗較高、效率較低的單效蒸發(fā)器。近年能耗低、效率高的多效蒸發(fā)器逐漸替代了單效蒸發(fā)器,最為常見(jiàn)的是三效蒸發(fā)器。早期的三效蒸發(fā)器多為手動(dòng)控制使得其在生產(chǎn)過(guò)程中的能耗及效率不甚理想,為了提高三效蒸發(fā)器工作狀態(tài)的穩(wěn)定性,降低能耗、提高效率,研究三效蒸發(fā)器的自動(dòng)控制方法具有重要意義。本文是受廣西師范大學(xué)環(huán)資學(xué)院植物成分提取實(shí)驗(yàn)室的委托,對(duì)該實(shí)驗(yàn)室原有的設(shè)備一手動(dòng)控制的三效蒸發(fā)器所設(shè)計(jì)的技術(shù)改造方案,該設(shè)備主要用于羅漢果甜苷提取液的濃縮工藝中。針對(duì)該濃縮對(duì)象濃度較高時(shí)粘性大、流動(dòng)性差的特點(diǎn),確定改造后的蒸發(fā)器工作方式為逆流三效自循環(huán)方式,并根據(jù)其工藝流程設(shè)計(jì)一套自動(dòng)控制系統(tǒng),以求改造完成后能達(dá)到降低能耗、提高效率、操作便利的目的�？刂葡到y(tǒng)以PLC為控制核心,以安裝有MCGS工控軟件的PC和觸摸屏為上位機(jī)構(gòu)建。PC用作過(guò)程監(jiān)控,觸摸屏用于現(xiàn)場(chǎng)控制,具有自動(dòng)控制模式和手動(dòng)控制模式。對(duì)蒸發(fā)器的控制主要有以下幾個(gè)部分,生蒸汽壓力的控制、各效分離室及原料罐液位的控制、蒸發(fā)室真空度的控制、成品液濃度的控制、一效二次蒸汽流量的控制等。其中一效二次蒸汽流量的控制相關(guān)變量較多,簡(jiǎn)單的PID控制已無(wú)法滿(mǎn)足控制要求,在本文中采用前饋模糊PID算法實(shí)現(xiàn)一效二次蒸汽流量的控制。關(guān)鍵參數(shù)的控制,在編寫(xiě)相關(guān)PLC的控制程序前依據(jù)所確定的控制策略進(jìn)行Matlab仿真,確認(rèn)其合理性后,再通過(guò)編寫(xiě)PLC應(yīng)用程序予以實(shí)現(xiàn)�？刂葡到y(tǒng)設(shè)計(jì)完成后,在我院工控實(shí)驗(yàn)室進(jìn)行了現(xiàn)場(chǎng)應(yīng)用前的模擬調(diào)試,并對(duì)模擬調(diào)試中暴露的問(wèn)題進(jìn)行了改進(jìn)。模擬調(diào)試的結(jié)果表明控制系統(tǒng)對(duì)傳感器信號(hào)采集正常,控制動(dòng)作穩(wěn)定可靠,監(jiān)控界面工作正常。文中對(duì)所采用的改造方案及三效逆流蒸發(fā)器的工藝流程作了介紹,給出了技術(shù)改造所需器件的選型,控制系統(tǒng)原理圖,對(duì)所編寫(xiě)的PLC關(guān)鍵程序、PC機(jī)實(shí)時(shí)監(jiān)控界面的功能及組態(tài)方法和觸摸屏界面的控制功能作了介紹,并重點(diǎn)對(duì)一效二次蒸汽流量的控制策略的原理方法、Matlab仿真以及控制程序的編寫(xiě)作了重點(diǎn)闡述。
[Abstract]:In the industrial production of food, pharmacy and chemical industry, the evaporator with steam as the heat source is widely used in the concentration process of raw liquid. The early evaporators were usually single-effect evaporators with high energy consumption and low efficiency. In recent years, the multi-effect evaporator with low energy consumption and high efficiency has gradually replaced the single-effect evaporator, the most common of which is the three-effect evaporator. In order to improve the stability of the three-effect evaporator, reduce the energy consumption and improve the efficiency, the early three-effect evaporator is mostly controlled by hand, which makes the energy consumption and efficiency of the evaporator in the production process not ideal, so as to improve the stability of the three-effect evaporator. It is of great significance to study the automatic control method of three-effect evaporator. This paper is commissioned by the Plant composition extraction Laboratory of Huanzi College, Guangxi normal University, to design a technical transformation scheme for the original equipment of the laboratory, a manual controlled three-effect evaporator. The equipment is mainly used in the concentration process of the extract of the glucoside of Siraitia grosvenori. In view of the characteristics of viscosity and poor fluidity when the concentration of the condensed object is high, it is determined that the working mode of the revamped evaporator is the reverse flow three-effect self-circulation mode, and a set of automatic control system is designed according to its technological process. In order to achieve the purpose of reducing energy consumption, improving efficiency and convenient operation after the revamping. The control system uses PLC as the control core, PC with MCGS industrial control software and touch screen as the upper mechanism for process monitoring. The touch screen is used for field control, with automatic control mode and manual control mode. The control of evaporator mainly includes the following parts: the control of steam generating pressure, the control of liquid level in each separation chamber and feedstock tank, the control of vacuum degree in evaporation chamber, the control of the concentration of finished product liquid, the control of primary and secondary steam flow rate, etc. There are many variables related to the control of primary and secondary steam flow, and the simple PID control can no longer meet the control requirements. In this paper, the feedforward fuzzy PID algorithm is used to realize the control of primary and secondary steam flow. For the control of key parameters, the Matlab simulation is carried out according to the determined control strategy before writing the control program of the related PLC, and then realized by writing the PLC application program after confirming its reasonableness. After the design of the control system was completed, the simulation debugging was carried out in the industrial control laboratory of our hospital before application, and the problems exposed in the simulation debugging were improved. The results of simulation and debugging show that the control system can collect the sensor signal normally, the control action is stable and reliable, and the monitoring interface works normally. In this paper, the retrofit scheme and the process flow of the three-effect countercurrent evaporator are introduced, and the selection of the device and the schematic diagram of the control system are given. The functions and configuration methods of the PC real-time monitoring interface and the control function of the touch screen interface are introduced. The principle and method of the control strategy of primary and secondary steam flow are emphasized. The Matlab simulation and the programming of the control program are emphasized.
【學(xué)位授予單位】：廣西師范大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：TP273

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