Automatic load-variable multi-variable control method for air separation device

Abstract

The invention discloses an automatic load-variable multi-variable control method for an air separation device. According to the method, a module 1, namely a gain scheduling module, a module 2, namely a dynamic multi-variable model prediction control module, and a module 3, namely a process real-time optimization module are involved. The method comprises the following steps that: the module 3 calculates the optimal steady state value of a process variable related to load change according to the load-variable requirement of the device and sends the optimal steady state value to the module 2; the module 1 determines a prediction model adopted by a controller of the module 2 at the moment according to the current value of a scheduling variable; and the module 2 gradually pushes the device to the optimal steady state working point which is calculated by the module 3 on the premise of ensuring product quality and not going against equipment constraints. By the method, the problems of mutual decoupling of energy and a material, nonlinear control and the like in the wide-range load-variable process of the air separation device can be radically solved, smooth and quick transition among different working conditions is realized, and the load-variable operation quality and speed of the air separation device are ensured.

Description

technical field [0001] The invention belongs to the technical field of air separation control engineering, and in particular relates to an optimal control method for automatically changing loads in the air separation production process. Background technique [0002] In the internal compression process of the air separation unit, such as figure 1 As shown, the raw material air enters the lower tower after a series of operations such as compression, purification, pressurization, expansion and heat exchange, and performs preliminary fractionation operation in the lower tower to obtain oxygen-enriched liquid air, and further fractionation will convert oxygen-enriched liquid air It is sent to the upper tower to complete; through the rectification of the upper tower, the products liquid oxygen, liquid nitrogen and nitrogen will be obtained. The extraction of liquid argon is to extract a certain amount of argon fraction from the middle and lower parts of the upper tower, and pass t...

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Problems solved by technology

These factors increase the difficulty of air separation load variable operation, so that in the process of variable load, each unit of the device cannot be adjusted independently, so the conventional PID control is difficult to control the air separation variable load

[0005] Secondly, the large-scale variable load of the air separation unit will cause the nonlinear control requirements of the process

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