A kind of automatic variable load control method for air separation unit

Abstract

The invention discloses an automatic load change control method used for an air separation plant. The automatic load change control method comprises following steps that firstly, PFD data of key process parameters under various stations of flow design of the air separation plant are obtained; secondly, the variable serving as the final product flow is determined and serves as the target value set in the load change process of a flow operator; thirdly, the key middle variable is determined and is used for calculating the set point of a final PID controller; fourthly, the PID controller participating in the automatic load change is determined; fifthly, through fitting, a fitting function between the parameters in the second step and the third step, with the variable in the third step as the dependent variable and the variable in the second step as the independent variable is obtained; sixthly, through fitting, a fitting function between the parameters in the third step and the fourth step, with the variable in the fourth step as the dependent variable and the variable in the third step as the independent variable is obtained; seventhly, according to work point data of one process parameter under different stations, through the polynomial function, all work point models are subject to interpolation, and the load change liner change track of the process parameter is obtained; eighthly, starting and stopping of the automatic load change need to meet a certain condition; ninthly, according to the difference of the flow, the above parameters can be increased or decreased.

Description

technical field [0001] The invention relates to an automatic variable load control method of an air separation unit in the air separation production process, and belongs to the technical field of automatic control engineering of the air separation unit. Background technique [0002] In the process flow of the air separation unit, the raw air enters the lower tower after a series of operating links such as filtration, compression, pre-cooling, purification, pressurization, expansion and heat exchange. After the air is preliminarily rectified by the lower tower, oxygen-enriched liquid air is obtained at the bottom of the lower tower, and pure liquid nitrogen is obtained at the top of the lower tower, which is supercooled by the subcooler and then throttled into the upper tower; The liquid oxygen is obtained from the bottom of the tower, and after being compressed by the liquid oxygen pump, it enters the main heat exchanger, and after reheating, it exits the cold box as a gas-o...

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to overcome the deficiencies in the prior art, and provide a solution to the problems of mutual decoupling of energy and materials, easy overshoot and oscillation, etc. in the process of changing the load of the air separation unit, and ensure the stability of the air separation unit and product quality. Under the premise of realizing smooth and fast transition between different working conditions, the automatic variable load control method for air separation unit