Optimization of interbed distributors

ARCO Products Company and Brown and Root teamed up to develop trickle bed reactor internals for improved mixing and redistribution performance. Initial application was in a five-bed hydrocracking reactor, in which several beds experienced radial temperature gradients as high as 30--70 F by end of run. Bed temperature response to changes in quench rate was also poor. The challenge was to develop interbed distributors which will provide good gas/liquid mixing as well as: provide fast and predictable quench response; minimize the radial temperature gradients in each bed; handle the various single and mixed phase flow regimes that the catalyst beds experience during an operating cycle; fit into the existing interbed space; operate within a pressure drop limit. The result of the design effort is a seven stage interbed distributor that meets all the above objectives and was recently awarded a patent. This new two-phase flow mixer/redistributor system, which is particularly effective in low liquid flow operating regimes, has been operating successfully for 33 months. Radial temperature gradients are less than 10 F, and bed temperatures respond predictably to quench changes. By reducing peak bed temperatures, operating cycle length is extended. More uniform temperatures result in improved liquid yields, less gasmore » and better operability, which has eliminated concerns about temperature runaway.« less