水煤浆螺旋折流板预热器的流体力学和传热性能的数值模拟

Preheating of coal water slurry (CWS) before entering into gasifier can improve its gasification efficiency. Bingham model was used to calculate and compare flow and heat transfer performance of shell-and-tube heat exchangers with helical baffles (STHXsHB) and shell-and-tube heat exchangers with segmental baffles (STHXsSB) for CWS preheating. The feasibility of using STHXsHB to preheat CWS and effects of helical angle and overlapped degree on flow and heat transfer were studied. The results show that STHXsHB is more suitable for preheating CWS when the temperature difference per unit pressure drop is used as an evaluation criterion. Temperature difference has little variation with helical angle and overlapped degree, but pressure drop decreases significantly with the increase of helical angle or the decrease of overlapped degree for STHXsHB. STHXsHB shows better flow and heat transfer performance with larger helical angles and smaller overlapped degrees. The shell-and-tube heat exchanger with 40° helical angle and 0% overlapped degree is the best. The results can help to select type and structural parameters of CWS preheaters.