Heating furnace sales
Heating furnace sales
This article will give you a better understanding of our professionalism Heating furnace sales. The title of this chapter is somewhat inaccurate, because it is the temperature of the charge (workpiece) that needs to be controlled, not the temperature of the furnace. Despite this inaccurate title, it is retained in its current form because it has been widely used. According to the requirements of metallurgists, the goal is to bring the surface of the charge to a given temperature and maintain this temperature until a specified temperature uniformity is achieved in the charge, or to change the temperature of the charge according to a specified heating and cooling cycle. In both cases, the uniformity of the charge temperature is required for all parts of the furnace. The interior of the charge should reach a given temperature without exceeding this temperature. The reason is very simple. For each specific process (rolling, forging, bending, extrusion, annealing, heat treatment) and for each specific material, there is a minimum temperature that must be reached for the process to proceed smoothly. Temperatures that exceed the required value by a large amount are not only a waste of heat, but also often have undesirable consequences, such as excessive oxide scale, decarburization and operating difficulties. Temperature control at various locations in the furnace
If each exposed surface of the charge receives an equal amount of heat per unit time, then
temperature uniformity is achieved for all locations in the furnace. This statement applies to intermittent furnaces. In continuous furnaces, the temperature distribution along the width of the furnace must be uniform.
It should also be pointed out here that for some processes, uniformity of temperature in the furnace does not produce the best results. There is an example to prove the correctness of this statement. On the expansion machine, all parts of a long tube should arrive at the rolling mill at the same temperature.
This steel tube must be hotter at the rear than at the front when it comes out of the furnace. The steel tube is rolled out from the furnace surface.
It is difficult to achieve true uniformity of charge at all locations in the furnace by automatic control alone.
It is the result of a good furnace design and good operation.
The following factors affect the uniformity of temperature in the furnace: the arrangement of the electric heating elements or radiant tubes, the uniformity of the temperature of each radiant tube, the arrangement of the burners, the type of burners (bright flame or transparent flame), the speed and direction of the combustion products causing the circulation, forced circulation, the height of the burners and the furnace roof above the charge (in high-temperature furnaces), the arrangement of the heating ducts, the exhaust ports, and the muffle walls. The operating factors are: the placement of the charge, the adjustment of the burners, and the closing of some burners during the heating process.
In some heating processes that do not require a furnace, temperature uniformity is easily obtained.
If the current is passed through a bar of constant cross-section, the temperature rise is the same along the length of the bar except at the ends of the bar. The same effect can be obtained if the current is generated by the induction of alternating current in a coil around the bar.
Most of the design factors that contribute to uniform temperature in the furnace have been discussed in the sections “Capacity of the Muffle Furnace” and “Gas Movement” in the previous volume. Other factors are discussed in Chapter 2 of this book. Some other factors will be discussed below.
In a high temperature furnace, if the burners are located higher above the furnace floor, the heat flow to the charge will be more uniform than if the burners are located closer to the charge. In a high temperature furnace, it is seldom effective to install only one high position burner.
In a furnace with bottom heating, the combustion chamber is below the furnace floor and is usually a manifold with several outlets. The outlets for the combustion products on the manifold are called burners. The burners can be made very large, and their correct size is determined by bricks or special shapes.