Integrated Fin Tube Machine Tool Φ32-Φ51

Xinxiang Songjin Machinery Co., Ltd. is dedicated to the field of high-efficiency and energy-saving heat exchange tubes. The integrally formed finned tubes developed by the company are at the world's leading level. The integrally formed spiral finned steel tubes use No. 20 steel pipes compliant with the GB/T3087-2008 standard for seamless steel tubes for low and medium-pressure boilers, or 20G steel pipes compliant with the GB/T5310-2017 standard for seamless steel tubes for high-pressure boilers as the base tubes. These are processed through hot-rolled fin tube machines via rolling and pressing to form spiral finned heat exchange tubes with an integrated structure of fins and base tubes.   

Integrally formed spiral finned tubes are primarily used as next-generation heat exchange components in medium and high-pressure boiler economizers and air preheaters. They offer advantages such as "high efficiency, energy savings, cost-effectiveness, resistance to ash accumulation, wear resistance, long service life, and strong environmental adaptability." Compared to conventional bare tubes or high-frequency welded spiral finned tubes, the integrally formed spiral finned tubes produced by our company have the following technical advantages: 1. No welding required, longer service life. Integrally formed spiral finned tubes eliminate the need for welding, completely removing contact thermal resistance between the fins and the base tube and preventing fin loosening. They exhibit high efficiency, stability, and reliable heat transfer performance, with a longer service life, making them particularly suitable for harsh environments, such as economizers in circulating fluidized bed boilers with high flue gas velocity and hard particles. The weld adhesion rate of welded finned tubes is difficult to achieve at 100% and is challenging to inspect. Welding creates contact thermal resistance and requires post-weld thermal stress treatment. Long-term use can lead to weld cracking, causing fins to detach from the tubes and further increasing contact thermal resistance, which reduces heat transfer efficiency and necessitates tube replacement.

If a crack gap is 0.1 mm, with air's thermal conductivity at 0.021 kcal/(m²·h·°C), the thermal resistance reaches 0.0045 m²·h·°C/kcal, equivalent to the thermal resistance of a 180 mm thick steel plate. Integrally formed finned tubes do not suffer from the issues associated with welded fins. Their service life matches that of the base tube material and is 3-4 times longer than that of high-frequency welded or brazed spiral finned tubes. Higher heat transfer efficiency. Taking economizers as an example, the total heat transfer coefficient on the flue gas side is generally no more than 100 kcal/(m²·h·°C), while the heat transfer coefficient on the water side inside the tubes is as high as 5000~10000 kcal/(m²·h·°C). Thus, the flue gas side plays a dominant role in the heat transfer process. According to the heat transfer formula Q = kFΔt, increasing the heat transfer area enhances heat transfer. Experimental test reports from the State Key Laboratory of Multiphase Flow at Xi'an Jiaotong University indicate that the heat transfer coefficient of integrally formed spiral finned tubes is 6~7 times that of bare tubes. Thermal performance test reports on finned tube bundles also show that the Nusselt number (Nu) of integrally formed spiral finned tube bundles is about 4 times that of bare tubes, with a significantly higher heat transfer coefficient and improved heat transfer performance. In contrast, research literature on welded spiral finned tubes indicates that their heat transfer coefficient generally does not exceed that of bare tubes by a significant margin, and the Nusselt number (Nu) of their tube bundles is about 4 times that of bare tubes. Additionally, integrally formed finned tubes do not suffer from the inherent contact thermal resistance and weld adhesion issues of welded tubes. The fin roots feature a small R smooth transition, and the fin cross-section has a trapezoidal structure. These characteristics make the heat transfer performance of integrally formed finned tubes significantly superior to that of high-frequency resistance welded and brazed spiral finned tubes. Reduced tendency for ash accumulation, slagging, and clogging. Removing ash, slag, and fouling from heat transfer surfaces is a critical maintenance task for heat exchange equipment such as economizers.

Since the thermal conductivity of the ash and slag layer on the flue gas side of economizers is very low, even a thin fouling layer can create significant thermal resistance. Each millimeter of ash and slag layer is equivalent to a 400 mm thick steel wall. The presence of fouling thermal resistance not only reduces heat transfer but also significantly increases the tube wall temperature, leading to overheating and potential tube failure, which can cause accidents. The integrally formed finned tubes feature a small R smooth transition between the fin roots and the base tube, with a smooth surface that eliminates the ash accumulation, slagging, and clogging issues common in welded finned tubes due to folded and uneven fin roots. Even if some ash accumulates, it is easily blown off, ensuring effective heat transfer and improving operational economy. Higher tensile strength, pressure resistance, and wear resistance. Integrally formed finned tubes are produced by extruding and rolling thick-walled tubes, effectively subjecting the tubes to an additional high-temperature rolling process.

Safety performance evaluation reports from the China Special Equipment Inspection and Research Center and comprehensive technical inspection reports from the National Steel Product Quality Inspection Center indicate that the integrally formed spiral finned tubes produced by our company exhibit higher longitudinal tensile strength, yield strength, and hardness compared to the base tubes, i.e., the national standard boiler steel tubes 20 and 20G, though with a reduction in elongation. The increased hardness enhances the wear resistance of the integrally formed finned tubes, particularly the improved hardness of the fins, which is beneficial for resisting erosion by flue gas dust. This addresses the severe wear issue in fluidized bed boilers caused by high flue gas velocity and hard particles. The reduction in elongation, i.e., decreased plasticity, does not affect the use of the finned tubes, as manufacturing economizers with these tubes does not require tube bending (only end welding), and high plasticity is not a critical requirement. In summary, integrally formed finned tubes represent a new manufacturing method for spiral finned tubes and can be considered, within certain applications, as the next-generation product replacing high-frequency welded and brazed spiral finned tubes. The integrally formed finned tubes produced by our company have undergone comprehensive technical testing and evaluation by multiple national relevant agencies, meeting or exceeding the relevant standards for steel tubes used in the boiler industry. In terms of the quality assurance system, the company strictly adheres to the established "Integrally Formed Spiral Finned Steel Tube Production Process Operating Procedures," which cover specifications for processing machinery and equipment, operational procedures, raw material procurement, and product inspection.