Trickle flow catalyst utilization

Trickle Bed Reactors (2). A trickle bed reactor utilizes a fixed bed over which liquid flows without filling the void spaces between particles. The liquid usually flows downward under the influence of gravity, while the gas flows upward or downward through the void spaces amid the catalyst pellets and the liquid holdup. Generally cocurrent downward flow of liquid and gas is preferred because it facilitates... 

Under trickle-flow conditions, determinations of the reactor conditions (i.e., gas and liquid flow rates, packing size, liquid properties, etc.) when all catalyst particles are effectively wetted and the catalyst surface is 100 percent utilized. 

Determination of the Extent of Catalyst Utilization in a Trickle Flow Reactor... 

In this study a trickle flow reactor is considered to be obtaining maximum catalyst utilization if it is operating in plug flow with the catalyst fully contacted and there are no interphase mass transfer limitations external to the catalyst particles. An illustrative conversion (desulfurization) for a fully contacted plug flow reactor with no mass transfer limitations is plotted as a function of LHSV in Figure 1. ... 

A modified process development unit apparatus has been utilized in this study in which, for the same 200 cm packed bed of catalyst, normal once-through trickle flow operation can be compared to liquid-full batch operation. In the latter, the possibilities of incomplete catalyst wetting, axial dispersion, and interphase mass transfer limitations are not present and thus, maximum catalyst utilization is obtained. Comparison of the results of the two modes of operation for the specific system of interest leads to the following conclusions ... 

Diluted bed heavy oil hydrogenation trickle flow process development units at least 60 cm long obtain maximum catalyst utilization at up to 90 percent desulfurization at LHSV as low as 0.75 hr Maximum catalyst utilization for denltrogenatlon and hydrogen uptake at these conditions is also obtained. 

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