The Research Of Aotumatic Regulatory System In The Lng Copious Cooling Process

Natural gas was a kind of important energy material,and it was a kind of important chemical materials as well.Because of Natural gas was abundant,low price,high calorific value,and burning cleaner,so it gradually replaced coal,oil,etc.The purpose of this subject was to introduce automatic control system to the production of cryogenic gas process.PDI has the characteristics of system structure,simple algorithm and strong controllability.It can improve the dynamic characteristics and steady-state characteristics of the system.The PID algorithm is simple in principle,the physical meaning of the parameters is clear,and the theoretical analysis system is complete.It is very suitable for the natural gas industry automatic control.The purpose of this project is to introduce the automatic regulation system into the natural gas cryogenic process production process.For the natural gas cryogenic process,the rectification tower side heat exchanger outlet temperature control,the natural gas pressure control link and the compressor active surge control link will be The natural gas cryogenic process is linked with the automatic regulation system.Through the practical application of the automatic adjustment system to the actual work production,good results have been obtained.The paper is divided into four parts:The first part mainly introduces the principle,process and production equipment of natural gas cryogenic process,and analyzes the possibility of applying PID control system to natural gas cryogenic process.The natural gas cryogenic process is carried out through three processes of compression,fractionation and compression.The whole production process is extremely cumbersome.The device is complicated,the situation is high,and the temperature of the liquefied natural gas is below minus 100 °C,which is flammable and explosive.In the event of a problem the natural gas cryogenic device can cause a significant safety incident.So a combination of natural gas cryogenic processes and intelligent control are necessary.Usually in chemical production,general control systems use conventional PID control.For these simpler systems,the model is easy to set up,and a regular PID with a simple algorithm can be used.It has complexities and many uncertainties,so it is difficult to apply conventional PID controllers for control.The fuzzy controller adjustment of the PID parameters can be performed.The second part,intelligent control method was made in-depth discussions.It was the core of intelligent control system.how to design and development and to simulate human intelligence machine was suitable for more complex objects,and achieve higher performance and goals.Intelligent control method was made of neural network and fuzzy control.Artificial intelligence(AI)was a man who was used to simulate the thinking of knowledge processing system,with memory,learning,information processing,form language,inspired by reasoning,and other functions.Automatic control(AC)described the dynamics characteristics of the system,it was a kind of dynamic feedback.The third part,to accurately control the rectification tower side natural gas heat exchanger system and the outlet temperature,PDI system was used.In the natural gas cryogenic process,precise temperature control of the natural gas heat exchanger system on the side of the distillation column is desirable.The temperature control of the heat exchanger directly affects the liquid level of the column and the purity of the distillate components.The stability and the yield of the product have an impact.This chapter designs a PID controller for heat exchanger outlet temperature control.We propose a PID controller with optimization algorithm and simulate it.It proves that the increase of sampling time increases the stability time of the system under various working conditions.The forth part,the traditional linear PID and fuzzy control are combined to control the pressure control of the natural gas cryogenic process and the active surge of the compressor.The wide application of fuzzy theory in the field of control is completely determined by the characteristics of fuzzy control itself.Conventional PID control has simple algorithm.PID control and fuzzy control have their own advantages and limitations.If traditional linear PID and fuzzy control are combined,It is a very practical control method to improve the control performance of the system.This chapter combines fuzzy control with PID and applies it to some links and systems in the deep cryogenic process of natural gas,achieving good results.