空分装置纯化系统的节能控制系统的研究
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摘要
空分装置是石化工业中重要的生产设备之一,也是我国节能减排的重要目标对象之一。本文以空分装置中的分子筛纯化系统为研究对象,利用集散控制系统(DCS, Distributed Control System)对分子筛纯化系统切换控制进行改造,实现节能减排的目的。
在控制方案的选取上,原有分子筛纯化系统是一个按固定时间切换的开环控制系统,它的2台分子筛吸附器按固定时间交替工作,吸附水分和杂质,消耗了大量的污氮,减少了分子筛的使用寿命。而改造后的控制系统被设计为一个闭环控制系统,不但具有一定的抗干扰能力和自调节能力,而且能够通过系统反馈值(分子筛出口二氧化碳含量)与标准值比较决定是否切换分子筛,既节省了污氮冷吹量,又延长了分子筛的使用寿命。
在设备的改造上,采用具有极强抗干扰能力和通信功能的可编程控制器作为控制器。检测仪表采用红外线气体分析仪在线检测分子筛出口二氧化碳含量,通过集散控制系统实现空分装置分子筛纯化系统的自动控制。
在控制策略的更新上,由于过程之间存在着较强的相关性,故本文采用部分最小二乘PLS (Partial Least Square)回归法分析少量不相关的量,以达到对整个过程进行控制的目的。根据总的空气压力、空气温度和相关的湿度以及氧化铝和分子筛的厚度等计算氧化铝的最大循环时间和分子筛的最大循环时间,从分子筛纯化系统的历史数据中提炼出统计信息,利用部分最小二乘回归法建立分子筛纯化系统的统计模型,实现对分子筛纯化系统切换控制时间的预测。
经过实验和现场运行结果表明,本文所设计的空分装置纯化控制系统实现了分子筛切换的自动控制,有效地降低了能耗,满足了节能控制要求,实现了分子筛纯化系统节能减排的目标。
Air separation plant is an important part of petrochemical industry production equipment, is one of the important objectives of Chinese energy conservation and emission reduction. In this paper, the molecular sieve purification system of the air separation plant is researched, the distributed control system is designed to transform the research object and then conserve energy and reduce emission.
In selecting the control scheme, the original molecular sieve purification system is an open-loop control system that switching at regularly intervals, and the moisture and impurities are absorbed alternatively by two molecular sieve absorbers of this system, and a lot of waste nitrogen is used, and the life of molecular sieve is reduced. While the closed loop control system designed in this paper has the ability of anti-interference and self-adjust, besides it can decide whether to switch molecular sieve according to the feedback value (the carbon dioxide content at the outlet) and stander value of the system, the amount of waste nitrogen can be reduced and the life of molecular sieve can be extended.
In transforming the equipment, the Programmable Logic Controller with strong anti-interference ability and communication function is chosen. The carbon dioxide content at the outlet of molecular sieve is detected on-line by infrared gas analyzer, and molecular sieve is switched automatically according to the carbon dioxide content, so that the automatic control of molecular sieve purification system of air separation device can be implemented.
In updating control strategy, due to the close affinity among different processes, a small amount of irrelevant variables is analyzed using partial least-squares regression, in order to control the whole system. The maximum cycle time of alumina and molecular sieve according to the total air pressure, air temperature and relative humidity, besides the thickness of alumina and molecular sieve is computed, the statistic information is extracted from the history data of molecular sieve purification system, and the statistic model of molecular sieve purification system is built using partial least-squares regression, so that the carbon dioxide content at the outlet of molecular sieve purification system can be predicted, and then the switching time of molecular sieve purification system can be controlled.
The experiments and result of field operation shows, the automatic control of molecular sieve is realized by the purification system of air separation designed in this paper, the energy consumption is efficiently reduced, the demand for energy control is met, and the object of energy conservation and emission reduction of molecular sieve purification system is realized.
在控制方案的选取上,原有分子筛纯化系统是一个按固定时间切换的开环控制系统,它的2台分子筛吸附器按固定时间交替工作,吸附水分和杂质,消耗了大量的污氮,减少了分子筛的使用寿命。而改造后的控制系统被设计为一个闭环控制系统,不但具有一定的抗干扰能力和自调节能力,而且能够通过系统反馈值(分子筛出口二氧化碳含量)与标准值比较决定是否切换分子筛,既节省了污氮冷吹量,又延长了分子筛的使用寿命。
在设备的改造上,采用具有极强抗干扰能力和通信功能的可编程控制器作为控制器。检测仪表采用红外线气体分析仪在线检测分子筛出口二氧化碳含量,通过集散控制系统实现空分装置分子筛纯化系统的自动控制。
在控制策略的更新上,由于过程之间存在着较强的相关性,故本文采用部分最小二乘PLS (Partial Least Square)回归法分析少量不相关的量,以达到对整个过程进行控制的目的。根据总的空气压力、空气温度和相关的湿度以及氧化铝和分子筛的厚度等计算氧化铝的最大循环时间和分子筛的最大循环时间,从分子筛纯化系统的历史数据中提炼出统计信息,利用部分最小二乘回归法建立分子筛纯化系统的统计模型,实现对分子筛纯化系统切换控制时间的预测。
经过实验和现场运行结果表明,本文所设计的空分装置纯化控制系统实现了分子筛切换的自动控制,有效地降低了能耗,满足了节能控制要求,实现了分子筛纯化系统节能减排的目标。
Air separation plant is an important part of petrochemical industry production equipment, is one of the important objectives of Chinese energy conservation and emission reduction. In this paper, the molecular sieve purification system of the air separation plant is researched, the distributed control system is designed to transform the research object and then conserve energy and reduce emission.
In selecting the control scheme, the original molecular sieve purification system is an open-loop control system that switching at regularly intervals, and the moisture and impurities are absorbed alternatively by two molecular sieve absorbers of this system, and a lot of waste nitrogen is used, and the life of molecular sieve is reduced. While the closed loop control system designed in this paper has the ability of anti-interference and self-adjust, besides it can decide whether to switch molecular sieve according to the feedback value (the carbon dioxide content at the outlet) and stander value of the system, the amount of waste nitrogen can be reduced and the life of molecular sieve can be extended.
In transforming the equipment, the Programmable Logic Controller with strong anti-interference ability and communication function is chosen. The carbon dioxide content at the outlet of molecular sieve is detected on-line by infrared gas analyzer, and molecular sieve is switched automatically according to the carbon dioxide content, so that the automatic control of molecular sieve purification system of air separation device can be implemented.
In updating control strategy, due to the close affinity among different processes, a small amount of irrelevant variables is analyzed using partial least-squares regression, in order to control the whole system. The maximum cycle time of alumina and molecular sieve according to the total air pressure, air temperature and relative humidity, besides the thickness of alumina and molecular sieve is computed, the statistic information is extracted from the history data of molecular sieve purification system, and the statistic model of molecular sieve purification system is built using partial least-squares regression, so that the carbon dioxide content at the outlet of molecular sieve purification system can be predicted, and then the switching time of molecular sieve purification system can be controlled.
The experiments and result of field operation shows, the automatic control of molecular sieve is realized by the purification system of air separation designed in this paper, the energy consumption is efficiently reduced, the demand for energy control is met, and the object of energy conservation and emission reduction of molecular sieve purification system is realized.
引文
[1]Dr.Thomas Rathbone, Dr.Satish Chander Kler,戴炜臣.空气分离和过程综合展望[J],深冷技术,1995(5)：13～18.
[2]夏葵,姚艳霞,林韶宁等.空气低温分离技术的某些进展[J].深冷技术,2004(2)：P8-15.
[3]江楚标.低温法空气分离装置技术进展、差距和对策[J].深冷技术,1999(3)：1～12.
[4]廖治鹏.大型低温空分装置的技术现状及前景趋势[J].通用机械,2006(12)：16-20.
[5]肖家立.现代空分技术发展及其与工程设计的关系[J].深冷技术,2000(2)：7-9.
[6]陈龙,杨学峰,杨洪.分子筛纯化器再生活化过程的顺序控制[J].石油化工自动化,2006,6：48～49.
[7]王洪洋.鞍钢35000m3/h空分设备分子筛纯化系统的优化操作[J].深冷技术,2006(3)：46～48.
[8]周富俊,金梅华.浅议空分装置纯化系统的操作管理[J].甘肃科技,2008,24(9)：69～70.
[9]空分装置多尺度节能技术应用研究,国家科技部支撑计划项目(项目编号2007BAE17B03)任务书,2007.07.
[10]王丽丽,刘勃安等.空分技术读本[M].北京：化学工业出版社,2009.
[11]何其高.空分装置自动化[M].北京：机械工业出版社,1988.
[12]黄晓江.空分装置技术改造探讨[J].煤化工,2003(2)：20-23.
[13]施仁,刘文江.自动化仪表与过程控制[M].北京：电子工业出版社,1991.
[14]程国霞.空分装置纯化系统的自动控制系统[J].企业标准化,2008(9)
[15]刘翠玲,黄建兵.集散控制系统[M].北京：中国林业出版社,2006.
[16]白文峰,李宵燕.自动控制原理[M].长春：吉林科学技术出版社,2003年8月.
[17]金以慧.过程控制[M].北京：清华大学出版社,1993年4月.
[18]张振友.分子筛在空气纯化系统中的应用[J].杭氧科技,2006(3)：5-8.
[19]George E P, Gwilym M Jemkins(Eds), Time Series Analysis Forecasting and Control[M], San Francisco, Holdon-Day, CA,1970.
[20]郭旻,王煜武.分子筛吸附器单层床改造成双层床简介[J].深冷技术,1999(2)：32～33.
[21]李验.纯化系统自动控制与联锁保护系统[J].数字石油和化工,2006(11)：9-13.
[22]侯志林.过程控制与自动化仪表[M].北京：机械工业出版社,1999年11月.
[23]步彬,钱红军.空气净化系统循环时间的计算[J].冶金动力,2008,4：37～39.
[24]于微波,林晓梅,刘俊萍.微型计算机控制系统[M].长春：吉林人民出版社,2002年5月.
[25]李政.DCS在空分设备中的应用[J].机电工程,2000,17(3)：70-72.
[26]李政.DCS在空分设备变负荷控制中的应用研究[J].深冷技术,1998(3)：13～18.
[27]Richalet J, Model Predictive Heuristic Control application to Industrial Processes[J], Automatica,1978,14(1):413～428.
[28]于艳君.20000m3/h空分设备DCS控制系统的设计与应用[J].深冷技术,2005(4).
[29]Qin S J. Recursive PLS algorithms for adaptive data modeling. Computers Chem. Engng,1998,22(4/5):503～514.
[30]Buckley J, Sugeno Type Controllers are Universal Controllers[J], Fuzzy Sets and Systems,1993,53:299-303.
[31]潘立登,李大字,马俊英.软测量技术原理与应用[M].北京：中国电力出版社,2009.
[32]罗晓广,李晓梅.求解实对称带状矩阵特征值的一种分治算法[J],数值计算与计算机应用,1998,3：218～226.
[33]王惠文.部分最小二乘回归方法及其应用[M].北京：国防工业出版社,1999年4月.
[34]任若恩,王惠文.多元统计数据分析-理论,方法,实例[M].北京：科学出版社,1998年6月.
[35]胡国定,张润楚.多元统计分析方法[M].天津：南开大学出版社,1990.
[36]黄运成.应用线性回归分析[M].北京：中国人民大学出版社,1989.
[37]Bakshi, B.R. Multiscale PCA with application to multivariate statistical process monitoring. The American Institute of Chemical Engineering Journal,1998,44(7), 1596-1610.
[38]Wise, B.M., N. B. Gallagher, S. W. Bulter, D. D. white, G. G. Barna. A comparison of principal component analysis, multi-way principal component analysis, trilinear decomposition and parallel factor analysis for fault detection in a semiconductor etch process. Journal of Chemometris.1999,13(3～4):379-396.
[39]Wold, S., N. Kettaneh, and K. Tjessem. Hierarchical Multiblock PLS and PC Models for Easier Model Interpretation and as an Alternative to Variable Selection, J. Chemometrics,1996(10):463～482.
[40]李春富.基于数据的软测量建模方法及其应用的研究[D].清华大学工学位论文.2005.
[41]Trygg J, Wold S. Orthogonal projection to latent structures(O-PLS). J. Chemometrics, 2002(16):119～128.
[42]阎威武,朱宏栋,邵惠鹤.基于最小二乘支持向量机的软测量建模[J].系统仿真学报,2003,15(10)：1494～1496.
[43]郑小霞,钱锋.基于PCA和最小二乘支持向量机的软测量建模[J].系统仿真学报,2006,13(3)：739～741.
[44]杨秋霜.空气深冷分离装置的在线调优[D].北京：北京化工大学硕士学位论文,1991.
[45]刘银华,陈开瑞.可编程序控制器在分子筛吸附系统中的应用[J].化工自动化及仪表,2002,29(1)：56～58.
[46]陈新华.分子筛切换系统优化设计探讨[J].冶金动力,2001,5：38～41.
[47]薛定宇,陈阳泉.控制数学问题的MATLAB求解[M].北京：清华大学出版社,2005.
[48]廖常初,PLC编程及应用,机械工业出版社,2005.
[49]S7-200 CN可编程序控制器.
[50]S7-200中文系统手册,2004.
[2]夏葵,姚艳霞,林韶宁等.空气低温分离技术的某些进展[J].深冷技术,2004(2)：P8-15.
[3]江楚标.低温法空气分离装置技术进展、差距和对策[J].深冷技术,1999(3)：1～12.
[4]廖治鹏.大型低温空分装置的技术现状及前景趋势[J].通用机械,2006(12)：16-20.
[5]肖家立.现代空分技术发展及其与工程设计的关系[J].深冷技术,2000(2)：7-9.
[6]陈龙,杨学峰,杨洪.分子筛纯化器再生活化过程的顺序控制[J].石油化工自动化,2006,6：48～49.
[7]王洪洋.鞍钢35000m3/h空分设备分子筛纯化系统的优化操作[J].深冷技术,2006(3)：46～48.
[8]周富俊,金梅华.浅议空分装置纯化系统的操作管理[J].甘肃科技,2008,24(9)：69～70.
[9]空分装置多尺度节能技术应用研究,国家科技部支撑计划项目(项目编号2007BAE17B03)任务书,2007.07.
[10]王丽丽,刘勃安等.空分技术读本[M].北京：化学工业出版社,2009.
[11]何其高.空分装置自动化[M].北京：机械工业出版社,1988.
[12]黄晓江.空分装置技术改造探讨[J].煤化工,2003(2)：20-23.
[13]施仁,刘文江.自动化仪表与过程控制[M].北京：电子工业出版社,1991.
[14]程国霞.空分装置纯化系统的自动控制系统[J].企业标准化,2008(9)
[15]刘翠玲,黄建兵.集散控制系统[M].北京：中国林业出版社,2006.
[16]白文峰,李宵燕.自动控制原理[M].长春：吉林科学技术出版社,2003年8月.
[17]金以慧.过程控制[M].北京：清华大学出版社,1993年4月.
[18]张振友.分子筛在空气纯化系统中的应用[J].杭氧科技,2006(3)：5-8.
[19]George E P, Gwilym M Jemkins(Eds), Time Series Analysis Forecasting and Control[M], San Francisco, Holdon-Day, CA,1970.
[20]郭旻,王煜武.分子筛吸附器单层床改造成双层床简介[J].深冷技术,1999(2)：32～33.
[21]李验.纯化系统自动控制与联锁保护系统[J].数字石油和化工,2006(11)：9-13.
[22]侯志林.过程控制与自动化仪表[M].北京：机械工业出版社,1999年11月.
[23]步彬,钱红军.空气净化系统循环时间的计算[J].冶金动力,2008,4：37～39.
[24]于微波,林晓梅,刘俊萍.微型计算机控制系统[M].长春：吉林人民出版社,2002年5月.
[25]李政.DCS在空分设备中的应用[J].机电工程,2000,17(3)：70-72.
[26]李政.DCS在空分设备变负荷控制中的应用研究[J].深冷技术,1998(3)：13～18.
[27]Richalet J, Model Predictive Heuristic Control application to Industrial Processes[J], Automatica,1978,14(1):413～428.
[28]于艳君.20000m3/h空分设备DCS控制系统的设计与应用[J].深冷技术,2005(4).
[29]Qin S J. Recursive PLS algorithms for adaptive data modeling. Computers Chem. Engng,1998,22(4/5):503～514.
[30]Buckley J, Sugeno Type Controllers are Universal Controllers[J], Fuzzy Sets and Systems,1993,53:299-303.
[31]潘立登,李大字,马俊英.软测量技术原理与应用[M].北京：中国电力出版社,2009.
[32]罗晓广,李晓梅.求解实对称带状矩阵特征值的一种分治算法[J],数值计算与计算机应用,1998,3：218～226.
[33]王惠文.部分最小二乘回归方法及其应用[M].北京：国防工业出版社,1999年4月.
[34]任若恩,王惠文.多元统计数据分析-理论,方法,实例[M].北京：科学出版社,1998年6月.
[35]胡国定,张润楚.多元统计分析方法[M].天津：南开大学出版社,1990.
[36]黄运成.应用线性回归分析[M].北京：中国人民大学出版社,1989.
[37]Bakshi, B.R. Multiscale PCA with application to multivariate statistical process monitoring. The American Institute of Chemical Engineering Journal,1998,44(7), 1596-1610.
[38]Wise, B.M., N. B. Gallagher, S. W. Bulter, D. D. white, G. G. Barna. A comparison of principal component analysis, multi-way principal component analysis, trilinear decomposition and parallel factor analysis for fault detection in a semiconductor etch process. Journal of Chemometris.1999,13(3～4):379-396.
[39]Wold, S., N. Kettaneh, and K. Tjessem. Hierarchical Multiblock PLS and PC Models for Easier Model Interpretation and as an Alternative to Variable Selection, J. Chemometrics,1996(10):463～482.
[40]李春富.基于数据的软测量建模方法及其应用的研究[D].清华大学工学位论文.2005.
[41]Trygg J, Wold S. Orthogonal projection to latent structures(O-PLS). J. Chemometrics, 2002(16):119～128.
[42]阎威武,朱宏栋,邵惠鹤.基于最小二乘支持向量机的软测量建模[J].系统仿真学报,2003,15(10)：1494～1496.
[43]郑小霞,钱锋.基于PCA和最小二乘支持向量机的软测量建模[J].系统仿真学报,2006,13(3)：739～741.
[44]杨秋霜.空气深冷分离装置的在线调优[D].北京：北京化工大学硕士学位论文,1991.
[45]刘银华,陈开瑞.可编程序控制器在分子筛吸附系统中的应用[J].化工自动化及仪表,2002,29(1)：56～58.
[46]陈新华.分子筛切换系统优化设计探讨[J].冶金动力,2001,5：38～41.
[47]薛定宇,陈阳泉.控制数学问题的MATLAB求解[M].北京：清华大学出版社,2005.
[48]廖常初,PLC编程及应用,机械工业出版社,2005.
[49]S7-200 CN可编程序控制器.
[50]S7-200中文系统手册,2004.
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