Annealing furnace is not only a high temperature chemical reactor, but also a large and complex thermal equipment. In the production process, the heating adjustment and temperature control level of the annealing furnace have a direct restrictive effect on the production, the life of the furnace body and the main technical indicators of the whole plant. Therefore, the measurement and adjustment of the furnace body temperature and the pressure of each part of the annealing furnace has become an important, complex and technically demanding job in production. It is not only labor-intensive and polluting, but also requires a lot of manpower and material resources.
Improving the automation level of annealing production will be the key to solving the problem. Today, in the process of gradually expanding and deepening the industrial application, the computer automatic control technology of annealing furnace heating plays an important role in stabilizing heating, increasing heat consumption, improving the quality of steel products and labor productivity, improving the operating environment and prolonging the life of the annealing furnace.
With the development of advanced control systems such as industrial control machines, programmable controllers and distributed systems, the previous large-scale relays and analog instruments have been gradually replaced. Its software preparation is relatively simple. It can be programmed by itself without special programmers. Besides, it can not only be used independently, but also has strong communication ability, which is convenient for networking.
A variety of supplements have been made to the traditional negative feedback and single control system, so that the control performance is better. In previous control systems, the relationship between fuel and air was usually treated with ratio regulation. Due to the inconsistent response speed of the fuel and the air conditioning circuit, the instability of the calorific value of the fuel, and the change of the burner characteristics, it is difficult to guarantee this ratio relationship. Especially when the combustion load changes, the ratio cannot be maintained. To solve these problems, three cross-limiting methods for dealing with the air-fuel relationship have been developed: single-cross-limiting method, double-cross-limiting method, and improved double-cross-limiting method.
More and more control systems use modern control theory, control, adaptive control, self-correcting controller, self-tuning parameter controller, and some have been successfully applied in industry. For example, the microcomputer adaptive group control system of the bell annealing furnace uses the output tracking adaptive control technology in the modern control theory. In a word, the application of microcomputer creates conditions for the mathematical calculation of complex modern control theory.
In addition to the traditional closed-loop control at the on-site process level, the annealing furnace is also managed with host computer. The main functions of the host computer application program include monitoring interface, data storage, alarm recording, report generation, optimization control, etc. The expansion of the management system application not only greatly improves the application performance and practical value of the annealing furnace control system, but also improves the efficiency of the production process.