关键词: 外取热器, 传热系数, 折流板, 流化催化裂化（FCC）

Abstract: A new type of baffle catalyst cooler was proposed to solve the problem of low cooling capacity in fluid catalytic cracking (FCC) external catalyst cooler through installing several baffles at the downflow catalyst cooler in current commercial design. A large scale cold model experimental device was built to measure heat transfer coefficients in both dense and dilute regions of the two coolers. Experimental results show that heat transfer coefficients in the baffle catalyst cooler are higher than those in the downflow catalyst cooler, either in dense or dilute regions. Heat transfer coefficients relatively increase 26.9%-267.9% and 31.6%-152.5% in dense and dilute region, respectively. In dense region, the intensification effect mainly results to more particle radial movement, enhance particle axial mixture and smaller bubble size. In dilute region, particles from top inlet flow along the baffle and this could extend particle flow path. Especially, the pores in baffles distribute particles more uniformly in the bed, thus could increase the particle contact time fraction with tube surface. Mathematical correlations are proposed to predict heat transfer coefficients in dense regions of the two coolers with relative errors less than 20%.

Key words: external catalyst cooler, heat-transfer coefficient, baffle, fluid catalytic cracking(FCC)