Application of Spiral Finned Tube
In the boiler and other heat transfer equipment, the heat transfer coefficient of the two sides of the heat transfer wall is often very uneven. Such as the coal burner, the pipe outside the pipe is the forced convection of the water in the water. In this case, the heat transfer in the tube space needs to be enhanced. One of the most effective method is to use the fin (fin) to expand the tube surface area and promote the media turbulence, so as to strengthen the convection heat transfer between the gas and the tube wall. Tube fin type many, but develops in the annular fin base of spiral finned tube is the most widely used a basic tube type.
The main advantages of the use of spiral finned tubes are as follows:
To increase the heat exchange area and improve the heat transfer effect.
Reducing the space occupied by the heat, reduce the volume, especially suitable for boiler.
The stiffness of the fin tube is increased and the seismic capacity is improved.
The manufacturing method of spiral finned tube, which is commonly used in welded fin tube (high frequency welding, brazing), and the new type of fin and tube. The heat transfer performance of the finned tubes of different processes is different, and the contact resistance is the main factor. The welded fin tube is in the heat of the fin and tube, regardless of the high frequency resistance heating of the melted pressure welding, or the solder melts and diffusion welding. Integral fin tube without welding, completely eliminate the contact thermal resistance.
Spiral finned tube in the power, chemical, HVAC thermal energy and air conditioning and refrigeration field, especially coal economizer of boiler, superheater, the air preheater has been widely used.
The material of the boiler, the material of the boiler is generally high quality carbon structural steel, the national standard and the main specifications are:
1) by GB3087-1999 "for low and medium pressure boiler with seamless steel tube" standard of 20 steel pipe, main specifications (diameter x wall thick): Phi 32X3, Phi 38x (3 to 3.5), Phi 42~45 x (3 to 3.5), phi (50 to 58) x (3.5 to 4).
2) "by GB3510-1995 for high pressure boiler seamless steel pipe standard" 20G steel tube, main specifications: diameter (32~51) x (3.5~8) etc..