本文選題：三效蒸發器 + 一效二次蒸汽流量　； 參考：《廣西師范大學》2017年碩士論文

【摘要】：在食品、制藥及化工等工業生產中,以生蒸汽為熱源的蒸發器被廣泛應用于原料液的濃縮工藝中。早期這種蒸發器通常為能耗較高、效率較低的單效蒸發器。近年能耗低、效率高的多效蒸發器逐漸替代了單效蒸發器,最為常見的是三效蒸發器。早期的三效蒸發器多為手動控制使得其在生產過程中的能耗及效率不甚理想,為了提高三效蒸發器工作狀態的穩定性,降低能耗、提高效率,研究三效蒸發器的自動控制方法具有重要意義。本文是受廣西師范大學環資學院植物成分提取實驗室的委托,對該實驗室原有的設備一手動控制的三效蒸發器所設計的技術改造方案,該設備主要用于羅漢果甜苷提取液的濃縮工藝中。針對該濃縮對象濃度較高時粘性大、流動性差的特點,確定改造后的蒸發器工作方式為逆流三效自循環方式,并根據其工藝流程設計一套自動控制系統,以求改造完成后能達到降低能耗、提高效率、操作便利的目的。控制系統以PLC為控制核心,以安裝有MCGS工控軟件的PC和觸摸屏為上位機構建。PC用作過程監控,觸摸屏用于現場控制,具有自動控制模式和手動控制模式。對蒸發器的控制主要有以下幾個部分,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變量較多,簡單的PID控制已無法滿足控制要求,在本文中采用前饋模糊PID算法實現一效二次蒸汽流量的控制。關鍵參數的控制,在編寫相關PLC的控制程序前依據所確定的控制策略進行Matlab仿真,確認其合理性后,再通過編寫PLC應用程序予以實現。控制系統設計完成后,在我院工控實驗室進行了現場應用前的模擬調試,并對模擬調試中暴露的問題進行了改進。模擬調試的結果表明控制系統對傳感器信號采集正常,控制動作穩定可靠,監控界面工作正常。文中對所采用的改造方案及三效逆流蒸發器的工藝流程作了介紹,給出了技術改造所需器件的選型,控制系統原理圖,對所編寫的PLC關鍵程序、PC機實時監控界面的功能及組態方法和觸摸屏界面的控制功能作了介紹,并重點對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作了重點闡述。
[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.
【學位授予單位】：廣西師范大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TP273

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