【作者】 刘勇；

【导师】 曾志文；

【作者基本信息】 中南大学 ， 工程（专业学位）， 2022， 硕士

【摘要】 传统的粉体釉料熔制工艺采取的是空气燃烧或带蓄热体空气燃烧(空气预热)的方式,这种燃烧工艺燃料消耗量大,生产效率低,窑炉废气排放量大,因此熔制工艺成本非常高。随着能源价格的上涨,环保部门对废气排放量的控制要求日趋严格等因素,提高窑炉燃烧效率,降低能耗,控制废气排放已经成为了行业亟待解决的问题。因此,本文的主要工作以粉体釉料窑炉作为研究对象,采用“全氧燃烧”工艺替代原有的空气燃烧生产工艺。研究工作从“全氧燃烧”工艺原理入手,论证了新工艺在粉体釉料行业的可行性,提出了新的窑炉改造方法和工艺自动控制的方法。同时,结合工艺流程,安全要求等,系统采用了更便捷的现场供气模式、撬装调压装置等,为客户降低初始投资成本,实现节能减排的目标。本文首先对窑炉的现状进行了介绍,提出了窑炉技术改造目标。通过对窑炉的火焰空间数学建模及Fluent仿真分析,结果表明采用“全氧燃烧”工艺不会对窑炉造成损伤,加速缩短窑炉的使用周期,论证了“全氧燃烧”可适用于粉体釉料窑炉。同时,对新工艺采用自动控制方案并基于燃烧理论,计算出了窑炉热量与物料的关系,推算出了氧气与天然气的最佳燃烧比例,可减少废气排放量等经济性指标,并提出了工艺控制关键点。本文针对天然气及氧气流量波动等造成的潜在安全风险,采用双交叉的流量限幅控制方案,解决了流量自动跟随,上限控制的问题。同时,为防止流量计装置计量错误,系统创新性的引入了流量故障保护控制,流量速度根据阀门的Kv系数计算,自动判定临界流量,可有效地防止天然气带来的爆燃风险。在氧气燃气比控制问题上,提出了不同的控制解决方案并基于MATLAB仿真实验,论证了采用模糊预测控制能实现更稳定的“氧燃”比,进一步节约燃料成本。其次,在系统硬件选用及设计方面,基于工艺安全规程,硬件采用高精度的压力传感器,质量流量计,比例控制阀及成熟稳定的西门子PLC控制系统等,确保系统精准的执行。在软件设计上,采用西门子“博途V13”软件进行系统组态,设计人机界面窗口和编写程序控制语句。最后,通过系统调试、测试运行,窑炉“全氧燃烧”控制系统运行稳定,粉体釉料产品质量达标。经核算,实际的天然气吨单耗节约率为45%,燃烧效率提升了2.3倍,二氧化碳排放减少205吨/年,符合设计预期水平。图39幅,表16个,参考文件63篇更多还原

【Abstract】 The traditional powder glaze melting adopts air combustion or air combustion with regenerator(air preheating).This manufacturing process need high fuel consumption,inefficiency and made huge exhaust emissions,cost very high.With the rise of energy prices,environmental protection departments have made strictly requirements on the control of emissions,improving furnace combustion efficiency,reducing energy consumption and controlling waste gas emissions have become an urgent problem to be solved in the industry.Therefore,the main work of this paper takes the powder glaze kiln as the research object,and adopts the "all oxygen combustion" process to replace the original air combustion production process.The research work starts with the principle of "all oxygen combustion" process,demonstrates the feasibility of the new process in the powder glaze industry,and put forward new furnace transformation methods and process automatic control methods.At the same time,combined with the process flow and safety requirements,the system adopts a more convenient on-site gas supply mode,skid mounted pressure regulating device and etc.,to reduce the initial investment cost for customers and achieve the goal of energy conservation and emission reduction.This paper introduced the current situation of the kiln in the first and put forward the goal of technical transformation of the kiln.Through the mathematical modeling of the flame space of the kiln and by the “Fluent” simulation analysis,it is proved the "all oxygen combustion" process will not cause damage to the kiln and accelerate the shortening of the service life of the kiln.So,"all oxygen combustion" can be applied to powder glaze kiln.At the same time,the new process adopts the automatic control scheme and based on the combustion theory,calculates the relationship between furnace heat and materials,the optimal combustion ratio of oxygen and natural gas,reduced waste gas emissions and other economic indicators and puts forward the key points of process control.Aiming at the potential safety risks caused by the fluctuation of natural gas and oxygen flow,this paper adopts a double crossing flow limiting control scheme to solve the problems of automatic flow following and upper limit control,which can effectively prevent the deflagration risk caused by natural gas.At the same time,in order to prevent metering errors of the flowmeter device,the system innovatively introduces flow fault protection control.The flow rate is calculated according to the Kv coefficient of the valve,and the critical flow is automatically determined,which can effectively prevent the risk of deflagration caused by natural gas.To the problem of control oxygen fuel ratio,different control solutions are proposed and based on MATLAB simulation experiments,it is demonstrated that fuzzy predictive control can achieve more stable "oxygen fuel" ratio and further save fuel costs.Secondly,in terms of system hardware selection and design,based on process safety regulations,high-precision pressure sensors,mass flowmeters,proportional control valves and mature and stable Siemens PLC systems are used to ensure the accurate implementation of the system.For software designing,Siemens "Botu V13" software is used for system configuration,designing man-machine interface windows and editing program control statement.Finally,through system debugging and test running,the furnace control system runs stably,and the quality of powder glaze products reaches the standard.According to the calculation,the actual saving rate per ton of natural gas is 45%,the combustion efficiency is increased by2.3 times,and the carbon dioxide emission is reduced by 205 tons/year,which is meet the design expectation level.更多还原