On-line diagnosis and selective control method and device for abnormal working conditions of heat exchanger leakage

Abstract

The invention discloses an online diagnosis and selective control method and device for leakage current unusual service conditions of a heat exchanger. The online diagnosis method for leakage current unusual service conditions of the heat exchanger comprises the following steps: establishing a dynamic mathematical model of the leakage current unusual service conditions of the heat exchanger; identifying the model gain of the dynamic mathematical model on line by adopting a least squares recursive algorithm; and performing online diagnosis on the leakage current unusual service conditions of the heat exchanger according to the symbol change of the model gain. The selective control method for leakage current unusual service conditions of the heat exchanger comprises the following steps: respectively establishing a normal controller which operates under normal service conditions of the heat exchanger and an abnormal controller which operates under leakage current unusual service conditions of the heat exchanger according to the dynamic mathematical model; setting a selector between the normal controller and the abnormal controller, wherein the selector is switched between the normal controller and the abnormal controller according to the diagnosis result of the online diagnosis method. The method is high in calculation real-time property, small in time delay, convenient to implement and low in total cost.

Description

technical field [0001] The invention relates to the system engineering field of petrochemical industry, in particular to a method and device for on-line diagnosis and selective control of abnormal working conditions of heat exchanger leakage. Background technique [0002] The heat exchanger is a very important energy recovery system in the petrochemical process. The operation and control of the heat exchanger will directly affect the total cost of the system, product quality and even production safety. In the process of petrochemical industry, the heat exchanger is often loaded with strong corrosion, high temperature, high pressure and other fluids. Due to the inconsistent degree of thermal expansion and contraction of various parts and the fluid-induced vibration and other factors, the heat exchanger is often damaged and sometimes damaged. Abnormal leakage occurs. On the other hand, the abnormal condition of heat exchanger leakage is often hidden and difficult to monitor a...

AI Technical Summary

Problems solved by technology

Once there is one or more heat exchanger leakage in the heat exchange network, there are many disadvantages in using simple PID control: (1) If the flow rate of the leakage stream is the manipulated variable, when leakage occurs due to the simple PID control It will further increase the flow rate of the leakage stream, resulting in an increase in the leakage flow rate while the controlled temperature still deviates from the given value; (2) Due to the existence of the control deviation, according to the PID control algorithm, the flow rate of the leakage stream will continue to increase, resulting in Energy and quality loss and even pollution to the environment and materials, causing production hazards

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