Technical requirements for convection plate of bell type annealing furnace

The convection plate of the bell type annealing furnace requires a reasonable structure, increasing air flow as much as possible, high strength, non deformability, and low price. This can be considered from both material selection and design structure. The middle and top convection plates should be Q235. The bottom convection plate is heavy and not frequently replaced. It is best to use heat resistant steel structures. However, due to width limitations, heat resistant steel plates are not easy to buy. Therefore, 20g or Q235 steel structural members can be used instead. There have been more than one attempts at heat-resistant steel castings, but they have all failed due to crack damage.

The geometric dimensions of the convection plate in the bell type annealing furnace depend on the geometric dimensions of the steel coil. For example, if the maximum outer diameter of the steel coil is 2000 mm and the inner diameter is 610 mm, the outer diameter of the convection plate should be 2000 mm and the inner hole should be 580 mm. The greater the thickness of the convection plate, the greater the stiffness and ventilation, and the better the heat exchange effect. However, it increases the charging height and consumes more gas during the annealing process. The general thickness is 55-92mm.

The bell type annealing furnace production line, Cibao New Sheet Metal (Jiangsu) Co., Ltd. currently has 90 sets of high-temperature bell type annealing furnaces with an annual output of 60000 tons

Bell type annealing furnace - Bell type annealing refers to the annealing of cold rolled sheets and strips in the form of stacking in a bell type annealing furnace.

Bell type annealing furnace - Bell type annealing refers to the annealing of cold rolled sheets and strips in the form of stacking in a bell type annealing furnace.

The coils are stacked in the middle of the hood type annealing furnace, with convection plates spaced between the coils of the same stack. Each stack is typically placed with four coils, covered with a heat resistant inner cover.

Bell type annealing furnace - There are two types of bell type annealing: single stack type and multiple stack type. The multi stack type can place 2 to 8 stacks of tape coils on a rectangular hearth, with separate inner covers fastened on each stack. The two inner covers on each hearth share a common outer cover. A circulating fan is installed at the lower part of the inner cover of the bell type annealing furnace to strengthen the control of the atmosphere and promote the convection heating of the coils. There are two types of coil annealing: tight coil annealing and loose coil annealing. Tight coil annealing is the most widely used; Unwinding annealing requires a unwinding unit, which is only used for heat treatment with special requirements.

Bell type annealing furnace heating is divided into radiant tube heating and direct flame heating (direct heating type). The direct heating type is most commonly used. The cooling process of bell type annealing furnace often adopts the internal cooling method of full flow cooling and split flow cooling, and the cooling hood is used for forced external cooling.

Bell type annealing furnace - The bell type annealing process system is mainly determined based on factors such as the chemical composition of steel, product quality and technical standards, plate and strip size, coil weight, and is also directly related to the furnace type structure used.

Bell type annealing furnace - The development trend of bell type annealing is to increase the charging capacity; Improve heating and cooling efficiency; Adopt strong convection to enhance heating capacity; Adopt fast cooling devices inside and outside the furnace to shorten cooling time; Improve sealing to ensure bright surface of strip steel; The entire annealing process is controlled by a computer.