Chemical apparatus and process disinfecting – deodorizing – preser – Chemical reactor – Including solid – extended surface – fluid contact reaction...
Patent
1995-07-21
2000-02-01
Tran, Hien
Chemical apparatus and process disinfecting, deodorizing, preser
Chemical reactor
Including solid, extended surface, fluid contact reaction...
422177, 422180, 422211, 50252719, 50252721, B01J 3504, B01J 1932
Patent
active
060199512
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a reactor for reacting catalytically therein at least one gas and at least one liquid.
The invention particularly relates to such reactor for treating oil products, such as for instance the desulfurization of heavy oil by means of hydrogen gas, for which reason the invention will be explained hereinafter with reference to this practical example, but it is emphasized that the invention is not limited to this use.
In practice, desulfurization of heavy oil by means of hydrogen gas takes place in a reactor filled with granular catalyst material, which is state of the art for such reactor. Accordingly, each separate catalyst element has the shape of a granule and can for instance have the shape of a sphere, an elongate cylinder or a flat cylinder (pill) The catalyst granules are dumped in a random manner, and the mutually supporting catalyst granules define a capricious pattern of passageways therebetween. The heavy oil and the hydrogen gas are pressed through these passageways and react with each other, the material of the granules playing a catalyzing part.
This involves various problems.
A first problem concerns the size of the separate catalyst granules. The greater the granules are chosen to be, the smaller the available exterior catalyst surface area in proportion to the catalyst volume or catalyst weight. If the catalyst material consists of a porous support including the active catalyst, this means that in the case of greater granules it becomes increasingly difficult to allow the active catalyst located in the interior of the catalyst granules to contribute efficiently to the reaction (diffusion limitation) to be catalyzed. Hence, a greater dimension of the catalyst granules is accompanied by a reduced efficiency.
However, the smaller the granules are chosen to be, the greater the flow resistance of the catalyst bed. Given the same yield, this means a greater pressure drop over the catalyst, which is synonymous with a greater loss of energy, and for forcing the substances to be reacted a greater power is needed.
A second problem concerns the manner in which the substances to be reacted can flow through the catalyst material. Due to the relatively great pressure drop over the catalyst material, it is practically impossible, at least for large-scale use, to allow the gas and the liquid to flow countercurrently. A method wherein the oil is allowed to drip from the top downwards through the catalyst bed and wherein the hydrogen gas is blown from the bottom upwards, is commercially pointless because of the slight maximum speed that can be used.
Therefore, it is known to present the oil and the hydrogen gas under a relatively high pressure to the reactor and to have them flow through the catalyst bed in the same direction. However, a number of important drawbacks are attached to the operation in such co-current mode, in particular when a gaseous reaction product is formed in the reaction to be catalyzed, such as is the case in the desulfurization of heavy oil by means of hydrogen gas, wherein in fact H.sub.2 S is formed. The further the liquid progresses in the reactor, the more it is polluted with that gaseous reaction product, which counteracts the reaction to be catalyzed. Further, the liquid, as it progresses further in the catalyst bed, will increase or decrease in temperature more and more, depending on whether the reaction to be catalyzed is exothermic or endothermic, so that in a commercial reactor provisions have to be made for maintaining the temperature within certain limits.
The object of the invention is to overcome the above-mentioned drawbacks.
In particular, a first object of the invention is to provide a reactor having catalyst elements whose active catalyst can be used highly efficiently, while yet these catalyst elements have only a relatively slight flow resistance.
A further object of the invention is to provide a reactor which is in particular suitable for being driven in a countercurrent mode.
To this end, according to the invention, the reactor of the above-me
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Cybulski Andrzej
Moulijn Jacob
Sie Swan Tiong
Michaelson Peter L.
Technische Universiteit Delft
Tran Hien
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