The Application & Study Of Advanced Process Control In FCCU

It is fair to say that the catalytic cracking of hydrocarbons(FCC)is one of the most important processes in the oil refining industry.Many industries purchased the advanced process control software package(APCSP)for FCCU to improve economicsof FCCU.The unit had a good performance by using those packages in early days,but the APCSP can't be used for a long time running on FCCU in china.By analyzing this reason,we found that the robust of the APCSP is not strong,and its maintenance is complicated.The unit model have changed with the long time running,but the usedmodel of those APCSP can't be updated on time or it is difficult to be updated.As the result is the APCSP is stopped using in factory. To deal with the shortcoming of the APCSP,this paper proposes a novel solutionThe solution comes from this idea,if we want to optimize a plant operation,the first thing we should do is optimizing every control loop of the plant.Based on this idea,the article acquires data and Add test signals by using OPC technique,and selects suitable database system and the technology of access database to save the acquired data.Using NLJ search procedure to optimize the control loops of FCCU plant by selecting PID parameters based on IMC control principle and step response data.Exploiting the new computation method of close—loop transfer function to get easily the PID loop's close—loop transfer function.Finding out the model parameters identification by having the same step response between two different models to solve the problem of getting PID con'troller from IMC controller.To deal with the problem of PID tuning on the large disturbance processes and large dead—time processes of practical industrial processes control,a novel method of parameter identification with initial s,tate identification at the same time(sot)were putted forward。Developing the new method of PID tuning using SOl and PRBS test signal。Application of the FCCU lumping model on the plant has been talked in this paper,and verified the validity of getting the lumping Rate Constants using NLJ search method.At last the feasibility of using PRBS test signal and SOl to identify the multivariable objects。 Based on the above theories and methods,a novel advanced process control software package of FCCU is developed,and the software package geeing a successfulapplication on FCCU process of Refinery Karamay PetroChina Co.Ltd。Practical application shows that the APCSP based on NLJ,IMC and S01 is advantageous ofbeing simple,practicable,economical and easy to realize for the PID optimization of the complex process system like FCCU.