Performance comparison of inline and staggered integrally-molded spiral finned tubes for low-carbon emissions

Abstract

The combined flue gas cooler with integrally-molded spiral finned (IMSF) tubes, which combines in-line and staggered tube bundles to leverage the performance advantages of different arrangement modes, has been proposed in this paper to simultaneously achieve heat transfer enhancement, ash deposition prevention, and wear resistance. The comprehensive performance including thermal–hydraulic, ash deposition, and wear performance of in-line and staggered IMSF tubes has not been reported and has been investigated with a multi-field coupled numerical model in this paper. Results show that for inline tubes, increasing the transverse pitch (PT) can reduce ash deposition and wear with slightly decrease in the thermal–hydraulic performance and increasing the longitudinal pitch (PL) can improve the thermal–hydraulic performance, with a significant increase in ash deposition when PL reaches to120mm, while for staggered tubes, decreasing the PT can enhance the thermal–hydraulic performance and reduce wear, with a sharp deterioration in ash deposition when the PT reaches 80 mm, and increasing the PL can decrease wear and has a minor impact on the thermal–hydraulic and ash deposition performance. Also, in the design of combined flue gas coolers, inline tubes should be placed at the front and two rows of dummy tubes placed before the inline tubes, and a larger PT and a moderate PL should be adopted to effectively reduces the overall tubes' wear and ash deposition; staggered tubes should be placed at the rear with an appropriate PT and a larger PL, enabling the full utilization of their excellent thermal–hydraulic performance while avoiding severe wear. This work can provide theoretical guidance and reference for the design and optimization of combined flue gas coolers to promote low-carbon emissions.