大型空分装置先进控制与优化策略研究

【作者】 刘震；

【导师】 唐雪飞； 孙平；

【作者基本信息】 电子科技大学 ， 软件工程， 2010， 硕士

【摘要】 空气分离是生产高纯度氧气、氮气、氩气和其它工业气体的重要工业生产过程。空分装置是钢铁、化工等企业的关键设备,随着空分设备的大型化,减少无功生产、降低氧气放散率,使供需保持平衡,并在低负荷时控制设备的总能耗以保持经济运行越来越受到空分用户的关注。目前大多数空分装置均采用了DCS控制系统,因此在原有的DCS控制系统的基础上增加上位管理计算机并配置符合生产操作原理和实际运行的优化控制软件,以实现自动变负荷生产操作是当前空分用户切实可行的措施,也是进一步提高空分装置自动化水平,实现节能降耗的迫切要求。由于空分设备耗电量大,因此如何将氧气放散率控制在5%以内是各钢铁企业重点研究和控制的目标。通过空分设施控制系统的升级改造,实现整空分设备负荷的在线调整,使之尽可能与生产匹配,是减少氧气放散率比较理想的方案。论文以天津钢铁公司2×28000Nm3/h空分装置为工业背景,进行先进控制优化,并在该装置横河CS-3000DCS综合控制基础上,实现对原有空分装置控制优化,实现自动变负荷先进控制技术。重点研究了如下的控制问题,通过对分子筛吸附特性的研究,把传统的“定时切换”再生控制改为自动改变切换时间的“适应控制”模式,使切换时间可以根据负荷大小及实际吸附情况自动修改,充分发挥吸附器作用,从而降低了能耗;实现进口空压机、增压机、氮压机的“裸机”控制,在DCS上开发了整套控制软件,替代了这些设备厂家的自带PLC控制系统,即所谓“黑匣子”,实现了升压快、启动电流小的节能型自动加载和自动卸载功能以及双参数防喘振控制功能;在以上先进控制优化基础上,串联整个空分流程,实现对空分设备的自动变负荷控制,以达到增强设备抗干扰能力、提高关键工艺参数的平稳性,改善产品质量一致性,并在产品合格的前提下,卡边操作,提高目的产品收率,实现节能降耗目的,同时优化工艺设备操作条件、减少劳动强度,实现装置处理能力最大化。更多还原

【Abstract】 Air separation is important productive process in industry to produce high-purity oxygen, nitrogen, argon and other industrial gases.Air separation unit is key equipment of iron&steel and chemical enterprises. Along with megatrends of air separating equipment, air separation customers increasingly concern on reduction of reactive power production, lower oxygen blow-off rate, balancing supply&demand, controling total energy consumption of equipment at underload to keep low cost operation. At present, most of air separateion equipments use DCS control system. So, currently it’s feasible method for air separation customers that increasing upper management computer based on initial DCS control system and configuring optimized control software which accord with production operating principle and actual working to achieve auto-varying load productive process, and it’s pressing request that further improving automatization level of air separation equipment to realize saving energy & reducing consumption.How to keep oxygen blow-off rate less than 5% is the target of control and key study points for all of iron&steel enterprises as air separation equipments are high power-consupmtion. It’s ideal scheme of reducing oxygen blow-off rate to achieve adjusting load of air separation equipment on line by upgrading & reforming the equipment’s control system and make it as match as possible with production.The thesis has its industrial background of the air separation equipment 2x28000Nm3/h of Tianjin Iron & Steel Group Co. to do advanced control optimization, achieve initial air separateion equipment optimization on the basis of multiple control of the equipment HENGHE CS-3000DCS to carry out auto-varying load advanced control technology. Mainly reserch the following control problems: By reserching adsorption characteristic of molecular sieve, change traditonal“time to switchover”regenerated control to automatically alter switchover time“Adaptive Control”mode,this makes switchover time can be adjusted automatically according to load size and actual adsorption status, give full play to adsorption function to cut down energy consumption. Achieve bare machine control of imported air compressor, supercharger, Nitrogen Compressor, developed full set of control software on DCS to replace the equipment manufacturer’s own PLC control systems i.e. so-called“Black Box”, this will realize functions of the quick step-up&small starting current energy-efficient auto-loading & auto-unloading as well as two-parameter anti-surge control. On the basis of above advanced controlling optimization, series connecting the whole air separation process to achieve auto-varying load controlling of the air separation equipments in order to enhance equipment’s ability to resist disturbance, raise stability of key technological parameter, improve consistence of products quality. Under precondition of making qualified products to improving yield co-efficiency of the object products to realize the goal of energy saving and consumption reducing, in the meantime optimize operating conditon of the processing equipment and decrease intensity of labor to maximize processing ability of the equipments.更多还原