Radiant tube heating combustion process
Radiant tube is widely used in heating furnace and is the main heating element of heating furnace. The radiant tubes currently used by radiant tube manufacturers are mainly divided into gas radiant tubes and electric heating radiant tubes. Among them, the thermal efficiency of gas radiant tube is about twice that of electric radiant tube. Therefore, gas radiant tube is the development trend of radiant tube in the future. Under the condition of modern market economy, the competition of radiant tube enterprises is becoming more and more fierce. In order to increase market share, all enterprises continue to improve radiant tubes. However, technological innovation is very difficult. In order to reduce the R & D cost of radiant tubes, enterprise R & D personnel should accurately predict the development trend of products and adopt theoretical methods and tools to realize product innovation and rapid design. Under the guidance of innovation theory, innovation practice will get twice the result with half the effort.
The development of products and their technologies always follows certain objective laws. The same law is often repeatedly applied to different product technology fields, that is, there are laws to follow in the process of product improvement and technological change in any field, and the creation and upgrading of all technologies develop powerful functions. TRIZ technology evolution theory is specialized in the evolution of technology system. It has experienced three stages: the traditional TRIZ evolution theory, the development of TRIZ evolution theory and direct evolution theory, including technology evolution theory (ET), technology evolution guidance theory (GTE) and direct evolution theory (DE). TRIZ technology evolution theory is specialized in the evolution of technology system. The theory of technological evolution reflects the important, stable and repeated interaction of technological systems, components, systems and environments in the process of evolution. Each evolutionary rule contains a different number of specific evolutionary routes and patterns. Using TRIZ's technology evolution theory, this paper analyzes the evolution process of the main performance of the radiant tube, summarizes and summarizes its evolution route, predicts its future development direction, and provides reference for the innovation and development of relevant products of enterprises.
Radiant tube heating and combustion process: in order to ensure the uniformity of heating temperature of strip steel, all continuous exit heating sections adopt radiant tube flame indirect heating. The high-temperature flue gas formed by the mixed combustion of fuel and combustion air flows, exchanges heat and discharges in the radiant tube. The heat is transferred to the radiant tube wall through radiation and convection, and then to the strip steel through radiation. This indirect heating shields the effects of high temperature area of gas combustion flame, air flow impact and atmospheric corrosion on the surface and properties of thin strip steel. The goal of the combustion process is to control the temperature uniformity of the radiant tube wall and ensure the product quality. 1. Continuous furnace withdrawal radiant tube heating combustion process radiant tube is used as the combustion space of continuous furnace withdrawal fuel. A burner is installed at one end of the radiant tube to organize fuel and combustion air to enter the radiant tube cavity for mixed combustion to form high-temperature flue gas. The high-temperature flue gas passes through the whole length of the radiant tube and is then discharged from the other end of the radiant tube. In the whole process of heat transfer between flue gas and radiant tube wall, two objectives need to be achieved: one is to improve the heat exchange efficiency between flue gas and radiant tube and increase the radiant tube wall temperature; The second is to ensure the uniform temperature of the radiant tube wall. At present, the advanced combustion process of annealing furnace: peroxide combustion process and flue gas reflux technology are adopted. 1.1 adjust the combustion control system of annealing furnace according to the production load. When the production load is high, the amount of gas required is large, the amount of flue gas formed after gas combustion is large, and the air flow fullness in the radiant tube is high, so that the heat transfer efficiency of the radiant tube wall is high and uniform; The production load is low, the amount of gas required is small, the amount of flue gas formed after combustion is small, and the space fullness of the same radiant tube is insufficient, which is easy to lead to uneven temperature of the radiant tube wall. In order to adapt to the production characteristics of annealing furnace, peroxide combustion process and dynamic air combustion ratio control are adopted, that is, when the production load is low, the amount of combustion air is increased, and there is still too much oxygen in the flue gas after combustion. Due to the peroxide combustion, the increase of flue gas volume can improve the flue gas fullness in the radiant tube and the uniformity of radiant tube wall temperature. At the same time, due to the increase of flue gas flow, the flue gas flow is accelerated, the flame is prolonged, and the temperature difference in the length direction of the radiant tube is reduced.
1.2 flue gas reflux technology introduces part of the flue gas discharged from the radiant tube into the end of the burner in a certain way at the tail of the radiant tube, and then circulates into the radiant tube. The waste heat of flue gas is directly utilized to greatly improve the thermal efficiency of radiant tube. At the same time, the flue gas flows back to the combustion part of the radiant tube, dilutes the temperature of the high-temperature area of the flame, improves the temperature uniformity of the wall and reduces the non generation. It is an effective energy-saving and emission reduction technology for radiant tube combustion Z. Flue gas reflux circulation mode is divided into: forced circulation, natural circulation, external circulation and internal circulation.