Analysis on the welding technology of the honeycomb jacket heat exchange plate

1. Overview of the structure of the honeycomb jacketed heat exchange plate

On the outside of the tank, various shapes of steel structures are installed by welding or flange connection to form a closed space with the outer surface of the cylinder, and heat exchange is conducted in this space The medium, heating or cooling the material, maintains the temperature of the material within a predetermined range, this kind of steel structure is collectively called a jacket. The honeycomb jacket is based on the overall jacket and adopts certain strengthening measures to strengthen the external pressure stability of the tank body, so as to save materials and improve the pressure bearing capacity of the jacket and the inner cylinder.

2. Manufacturing process of molded honeycomb jacket heat exchange plate

The honeycomb jacket plate is made by pressing a special mold on a stainless steel plate, and the material is generally stainless steel. The jacket has a thin wall, large diameter, many solder joints (the largest container has more than 10,000 honeycomb points), and large welding deformation. Therefore, effective anti-deformation measures must be adopted in the forming, teaming, and welding manufacturing process. The honeycomb hole welding process adopts GTAW welding, and the welding sequence can adopt the method of gradually unwelding each hole along a circle. After welding one hole, jump to another hole in a low temperature state for welding, that is, jump welding. There are two types of welding joints: plug welding and fillet welding.

3. Manufacturing process of laser welding honeycomb jacket heat exchange plate

The laser welding honeycomb jacket is formed by pressure bulging after laser welding. The specific process is shown in the following schematic diagram.

Generally, the surfaces of the thin stainless steel plate and the thick stainless steel plate are wiped clean before welding, the two plates are closely attached, and the honeycomb rings of the two plates are welded by laser deep penetration. If the welded honeycomb panel is used as a cylinder, it needs to be rolled into a cylinder, and then a certain pressure is used to swell the thin plate, so that there is a combination of the cylinder and the honeycomb jacket. If it is used as a regular head, such as a conical head, it needs to be rolled into a cone shape and then bulged. Finally, the bulging and forming components are connected by welding or flanges to form a honeycomb jacket device.

4. Comparison of advantages and disadvantages of molded and laser welded honeycomb jacketed heat exchange plates

(1) The laser welded honeycomb jacket has high strength. It can be seen from the above-mentioned molded and laser-welded manufacturing process that the laser-welded honeycomb jacket has a significant structural advantage compared with the molded honeycomb jacket: the honeycomb points are not open. Qualitative analysis from a mechanical point of view, the openings of the plate structure are often places where stress is concentrated, which weakens the load-bearing capacity of the entire structure. Therefore, the structural strength of the laser-welded honeycomb jacket should be better than that of the molded honeycomb jacket. This is also reflected in the same design conditions, the thickness of the laser welded honeycomb jacket is smaller than that of the molded honeycomb jacket. Take the honeycomb jacket used in the fermentation tank as an example, compare the empirical thickness values u200bu200bof the jacket when 25% alcohol water, steam, and liquid ammonia are used as the heat exchange medium.

(2) The laser welded honeycomb jacket has good heat transfer. The honeycomb jacket has a disturbing effect on the fluid due to the distribution of honeycomb points, and has a large heat transfer coefficient and a good heat exchange effect. The channel height h of the laser welded honeycomb jacket is smaller than the molded one. For example, the honeycomb jacket of liquid ammonia medium has a laser welded channel height of 3~4mm and a molded channel height of 8mm under a design pressure of 1.3MPa. The height of the channel is small, the fluid flow speed is fast, and because of the disturbing effect of the honeycomb points on the fluid, the heat exchange effect of the laser welded honeycomb jacket is better than that of the molded type.

(3) The laser welding honeycomb jacket has high efficiency and high quality stability. Compared with the widely used manufacturing process of pressing the honeycomb jacket first and then welding the assembly, the manufacturing process of the laser welding honeycomb jacket is much simpler and more convenient. The large-scale automatic CNC laser welding machine can weld honeycomb panels with a length of 14 meters and a width of 2 meters at one time, with high work efficiency. In comparison, the honeycomb with truncated truncated pits is press-formed, all (or part) of the honeycomb is punched with round holes at the bottom of the honeycomb, and the jacket is welded to the cylinder at the round hole. The entire jacket has tens of thousands of honeycomb holes. This welding The work is very cumbersome, and the welding quality control is also troublesome. Because the laser is directional, energy-intensive, welding distortion is small, and the welding seam surface is smooth and beautiful; and the welding process is automatically controlled by the CNC numerical control system, the processing accuracy is high, the mass welding quality is stable and reliable, and the human factor during manual welding is eliminated. In addition, through professional automatic programming software control, the welding pattern can be easily changed to meet the needs of different refrigerants, pressure resistance and heat exchange.