Pilot study on ascension-pipe heat exchanger used for waste heat recovery of coke oven gas

Abstract

Coke oven gas (COG) is syngas with abundant waste heat generated from coke-making process. Waste heat recovery of COG can be a useful solution to address issues of energy shortage and environmental protection. Empirical approaches to recover waster heat from COG are to re-combust residual heat, purify hydrogen and synthesize methane for energy generation. However, sensible heat of COG cannot be recovered in efficient manner. Ascension-pipe heat exchanger (APHE) as one of heat pipe heat changer is considered to mitigate such issues. However, few studies were implemented to analyze the thermal performance of APHE for waste heat recovery of COG. It might restrict the development of APHE used in coke oven plant. As a result, this pilot study aims to evaluate the overall heat transfer coefficient with different mass flow rate of working fluid and effectiveness of APHE in one period of coke-making process. The findings showed that overall heat transfer coefficient rises with the increase of mass flow rate of working fluid. The average effective of APHE in one period can reach around 69%. These can demonstrate that APHE is a promising choice to recover the sensible heat from COG. In addition, the temperature variation of COG during entire coke-making process needs to be concerned for accurate thermal performance evaluation of APHE.