Ebullated-bed process for feedstock containing dissolved hydrogen

摘要

An improved system and method for processing feedstocks in an ebullated-bed hydroprocessing reactor is provided in which hydrogen gas is dissolved in the fresh and recycled liquid feedstock by mixing and/or diffusion of an excess of hydrogen, followed by flashing of the undissolved hydrogen upstream of the reactor inlet, introduction of the feed containing dissolved hydrogen into the ebullated-bed hydroprocessing reactor whereby the dissolved hydrogen eliminates or minimizes the prior art problems of gas hold-up and reduced operational efficiency of the recycle pump due to the presence of excess gas in the recycle stream when hydrogen gas was introduced as a separate phase into the reactor.

主权项

1. A process for the conversion of a liquid hydrocarbon feedstock into lower molecular weight hydrocarbon compounds in an ebullated-bed catalytic hydroprocessing reactor, the reactor including a product outlet in fluid communication with a substantially catalyst-free region above the ebullated catalyst bed for transferring ebullated bed reactor effluents that include unreacted or partially reacted hydrocarbons, the process comprising:
mixing the liquid hydrocarbon feedstock with an excess of hydrogen gas in a mixing zone to dissolve a portion of the hydrogen gas in the liquid hydrocarbon feedstock to produce a hydrogen-enriched liquid hydrocarbon feedstock; conveying the hydrogen-enriched liquid hydrocarbon feedstock and undissolved hydrogen to a flashing zone in which at least a portion of undissolved hydrogen is flashed, whereby gas holdup in the ebullated-bed catalytic hydroprocessing reactor and recycle ebullating pump is reduced; passing the hydrogen-enriched liquid hydrocarbon feedstock from the flashing zone to the feed inlet of the ebullated-bed reactor for reaction that includes conversion of the feedstock into lower molecular weight hydrocarbons; recovering ebullated bed reactor effluents from the substantially catalyst-free region of the ebullated-bed reactor; passing the ebullated bed reactor effluents from the ebullated-bed reactor product outlet to an external recycle separation zone which includes an external separation unit or flash vessel inlet in fluid communication with the product outlet and an outlet in fluid communication with a recycle ebullating pump for passing the separation unit or flash vessel bottoms to the inlet of the ebullated-bed reactor; passing the external separation unit or flash vessel bottoms from which hydrogen and light gases have been removed to the recycle ebullating pump; and passing the separation unit or flash vessel bottoms from the recycle ebullating pump to an inlet of the ebullated-bed reactor.