Radiant tube

Type: W type, 200 mm Ø, 8 mm thickness

Structure: centrifugal cast heat resistant steel (straight section) and statically cast heat resistant steel (elbow part)

Material: pipes 1 and 225Cr35NiWStNr: 1.4857,

The remaining 25Cr20Ni WStNr: 1.4848

Due to the high temperature of the first and second pipes, the more temperature resistant material is used, while the rest of the material is lower grade, so as to save the cost of materials, so that each part plays the maximum efficiency. And the formulation of the specific material, from which the radiation tube heating radiation power or surface load to determine.

As can be seen from the above table, the material of the radiation tube has a great relationship on its life, working temperature and equipment potential.

Slow cooling and fast cooling section

functional characteristics

The function of the cooling section, as the name suggests, is to cool down the strip steel, but it is far from so simple. The cooling rate is greatly related to the chemical composition of the plate and the mechanical properties of the plate, which can be explained from metallolithography and metal heat treatment. High cooling rate can reduce the content of some alloy elements in the steel species, without the loss of their mechanical properties, that is, through physical means to achieve the purpose previously achieved by chemical means. Therefore, some steel types have certain requirements for the cooling rate, and there are several ways to increase the cooling rate: reduce the cooling length, improve the unit speed, increase the cooling capacity of the cooling medium, and sometimes by reducing the number of cooling units has not reached the requirements, it is necessary to increase the content of hydrogen.

In the fast cooling section, depending on the number of cooling zones used, the cooling system can obtain the following cooling rates for some specific products:

cooling-rate curves

For example, when cooling zone 1 & 2 operates, the yield can reach 81 tph with a cooling rate of 99.6°C / s for a strip of 0.7mm thickness.

For some products requiring high cooling rates, such as BH, DP and TRIP, for strip steel approximately 1.5 mm thick, cooling will be performed at high hydrogen in the cooling section, as shown in the figure below.

cooling-rate curves

For example, when the cooling zone 1 & 2 operates, the yield can reach 90 tph, and the cooling rate can reach 115°C / s for the strip steel of 0.7mm thickness.

For the steel type produced, the cooling rate of the fast cooling section is as follows:

Cooling rate table

a. The cooling rate is calculated at the effective length of the cooling section, and the strip temperature is calculated at the inlet and outlet of the fast cooling section.

Performance parameters of the fans in the slow and fast cooling sections

Note: All the fans are driven by a variable-speed motor.

Performance parameters of heat exchanger in slow cold section and fast cold section

3 units through the aging furnace chamber,

The operating temperature range is 300 to 400 °C in 12 zones. The arrangement of heating element is snake shape, with external air tightness connection, heating element type is resistance band, the material is 80Ni20Cr, silicon control control. The power is:

-Furnace 1 4 x 270 kW

-Furnace room 2 4 x 270 kW

-Furnace room 3 4 x 270 kW

Installation position of the rectifying roller