Mechanism Study of Waste Heat Recovery from Slurry by Surface Scraped Heat Exchanger

摘要

Waste-heat recovery from discharged slurries can improve the net raw biogas production in bio-methane process in order to meet the demand of a new generation of anaerobic digestion. In order to achieve a high efficient waste-heat recovery, in this work, a mathematical model of waste-heat recovery process with surface scraped heat exchanger (SSHE) was proposed with the consideration of the shear rate and temperature-dependent rheological behaviour. The convective heat transfer performance of SSHE was calculated numerically where slurry was considered. The contribution of waste heat recovery from the slurry to biogas production by SSHE and general shell-and-tube heat exchanger (STHE) were firstly calculated quantitatively, and the increase of net raw biogas production could be over 13.5% by SSHE with need of heat exchange area less than a quarter of STHE's, which showed a great potential to increase the net raw biogas production in bio-methane process with low equipment investments and more compactible structure.