Study on the gas–solid flow and heat transfer characteristics of evaporating recycle valve

Conventional recycle valve employed in the external circulation loop of CFB boiler was modified in the study for adapting the combustion and heat transfer characteristics of the small scale industrial CFB boiler. The evaporating immersed tubes were proposed to be set in the modified recycle valve which was treated as an evaporating recycle valve with integrated functions of solids recycle and heat transfer. The gas–solid flow and heat-transfer characteristics of the evaporating recycle valve were systematically investigated on a cold test rig and an industrial CFB boiler respectively. Based on the results, the low load performance of the industrial CFB boiler was discussed.