基于S7-400 PLC的置换蒸煮控制系统的应用研究

发布时间：2018-05-04 18:03

本文选题：置换蒸煮系统 + 温度一致性控制　；参考：《陕西科技大学》2017年硕士论文

【摘要】：造纸工业是我国的重要基础原料产业,但它的发展一直被高能耗、大污染和不合理的原料结构等问题所困扰。制浆是造纸工业的重要组成部分,当前仍沿用常规间歇式蒸煮工艺,能耗高、得率低,且后续漂白工段只能采用三段漂或四段漂,对环境的污染较大。而置换蒸煮技术,通过在蒸煮锅之外设置温黑液、热黑液、热白液等槽罐,将蒸煮工艺分为多个步骤进行,从而实现黑液里面的热能和化学品的回收再利用,后续浆料也可以采用新近研发出来的无元素氯漂或全无氯漂等先进漂白工艺,是一项节能环保的新型间歇式制浆技术,在美国、加拿大等造纸技术发达的国家已经被研发成熟并得以广泛应用。虽然我国已经成功引进了置换蒸煮技术,但是由于其蒸煮机理复杂、蒸煮流程繁冗且内部联锁复杂,因此国内目前仍没有一套功能完善且拥有自主知识产权的置换蒸煮全集成控制系统,所采用的置换蒸煮控制系统都是由ABB、Honeywell、SIEMENS等国外公司提供,成本昂贵,只有实力比较雄厚的大浆厂才有能力采购,因此实现置换蒸煮控制系统的国产化有利于置换蒸煮技术在我国的推广应用。基于上述原因,本硕士论文在科技部国家国际合作项目“节能环保型置换蒸煮关键技术与设备的合作研究”的资助下,以广西马山和发强纸业有限公司置换蒸煮DCS项目为依托,结合国合项目引进的技术资料对置换蒸煮生产溶解浆和化学浆的控制过程进行详细剖析,并从控制难点的研究与解决策略、控制方案设计、上位机程序设计与实现三个方面展开应用技术研究,具体研究内容如下:(1)控制难点的研究与解决策略以国合项目引进的GLV技术资料为依据,对置换蒸煮工艺过程控制进行详细剖析,在此基础之上解决置换蒸煮系统应用过程中的三个难点问题。其中针对蒸煮锅温差问题,设计了神经网络串级解耦PID控制算法,解决了温差控制的时滞性、时变性和非线性等难点;针对偏流问题,通过分析设计了通道的检测和破坏方案,保证蒸煮过程中药液以近活塞流的方式流动;针对卸料泵汽蚀问题,通过控制卸料浓度并结合变速卸料、补偿有效汽蚀余量的方法,保证在整个卸料过程中NPSHa大于NPSHr。(2)置换蒸煮控制方案的设计研究针对置换蒸煮工艺过程,提出了主顺序和子顺序相结合的控制方案,实现工艺过程的自动化;通过建模分析得到了基于物料平衡的槽区液位控制策略,使槽区液位始终保持在10%~90%之间,满足了置换蒸煮系统正常生产的要求;设计了冗余、联锁、诊断等方案,保证控制系统安全有效地运行,并通过OPC接口技术使MATLAB和PLC相结合,便于高级控制算法在置换蒸煮系统中的应用。(3)基于S7-400 PLC的控制系统的设计与实现以西门子S7-400 PLC为主体控制硬件,PCS7为软件开发工具,根据所提出的难点问题解决策略以及各控制方案,进行了DCS控制系统硬件、软件设计,使得所提出的解决策略和控制方案可应用于实际生产。本硕士论文剖析了GLV公司的置换蒸煮工艺,在此基础之上对置换蒸煮系统应用过程中的三个难点问题进行了分析和解决,并设计出了工艺自动化等控制方案,根据所提出的各难点解决策略及工艺自动化等控制方案,完成了DCS硬件、软件设计,在广西马山和发强纸业有限公司的实际应用结果表明,本硕士论文所研究设计的控制系统,可以很好地满足工业生产的实际需求。
[Abstract]:The paper industry is an important basic raw material industry in China, but its development has been plagued by high energy consumption, large pollution and unreasonable raw material structure. Pulping is an important part of the paper industry. At present, the conventional batch cooking process is still used, with high energy consumption and low yield, and only three or four stage bleaching can be used in the subsequent bleaching section. The pollution of the environment is great, and the replacement steaming technology can be divided into several steps by setting the hot black liquid, hot black liquid and hot white liquid outside the cooking pot, so as to realize the heat and chemical recycling in the black liquor, and the following slurry can also be used newly developed without chlorine bleaching or all chlorine bleaching. Advanced bleaching technology, which is a new type of intermittent pulping technology with energy saving and environmental protection, has been developed and widely used in the developed countries such as the United States and Canada. Although the replacement cooking technology has been successfully introduced in our country, the cooking process is complicated and the internal interlocking is complex because of its complicated cooking mechanism. At present, there is still not a complete set of complete integrated control system with complete function and independent intellectual property right. The replacement steaming control system is provided by foreign companies such as ABB, Honeywell, SIEMENS and so on. It is expensive, only the large pulp factory with strong strength has the ability to purchase, so the replacement cooking control system is realized. Based on the above reasons, the master's thesis, supported by the cooperation of the national international cooperation project of the Ministry of science and technology, "the cooperation of the key technology and equipment of the energy saving and environmental replacement steaming", is supported by the replacement of the DCS project of the Guangxi Mashan and the development of the paper industry Co., Ltd. The technical data introduced by the project are analyzed in detail for the control process of dissolving pulp and chemical pulp produced by replacement steaming, and the application technology is researched from three aspects: the research and solution strategy of the control difficulties, the design of control scheme, the program design and implementation of the upper computer, and the specific research is as follows: (1) the research and solution strategy of the control difficulty Based on the GLV technical data introduced by the national project, the control of the replacement steaming process is analyzed in detail. On this basis, three difficult problems in the application process of the replacement cooking system are solved. In view of the problem of the temperature difference of the cooking pot, a cascade decoupling PID control algorithm is designed to solve the time delay of the temperature difference control. By analyzing and designing the detection and failure scheme of the channel in order to ensure the flow of the near piston flow in the cooking process, the method of controlling the discharge concentration and compensating the effective cavitation allowance to ensure the NPSH in the whole unloading process is guaranteed. The design of a more than NPSHr. (2) replacement steaming control scheme is designed for the replacement steaming process. The control scheme combining the main sequence and the subsequence is proposed to realize the automation of the process. The liquid level control strategy based on the material balance is obtained by modeling and analysis, so that the liquid level of the slot area is kept between the 10%~90% and the liquid level. The requirements of normal production of replacement cooking system; design redundancy, interlocking, diagnosis and so on to ensure the safe and effective operation of the control system, and combine MATLAB and PLC through OPC interface technology to facilitate the application of the advanced control algorithm in the replacement cooking system. (3) the design and implementation of the control system based on S7-400 PLC based on the SIEMENS S7-400 PL C is the main control hardware, and PCS7 is a software development tool. According to the difficult problem solving strategy and the control scheme, the hardware of the DCS control system and the software are designed. The proposed solution strategy and control scheme can be applied to the actual production. The master's thesis analyses the replacement steaming technology of GLV company, on this basis The three difficult problems in the application process of the replacement cooking system are analyzed and solved, and a process automation control scheme is designed. According to the difficulty solutions and process automation control schemes, the DCS hardware and software design are completed, and the actual application results of the Guangxi Mashan and the hair strong Paper Co., Ltd. are completed. It shows that the control system designed by this master thesis can well meet the actual needs of industrial production.

【学位授予单位】：陕西科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TS733.2

【参考文献】