This invention relates to a process for the production of higher boiling hydrocarbons from lower boiling hydrocarbons in the presence of catalytic agents. Another aspect of the present invention relates to a process for the alkylation of isoparaffins such as isobutane with olefins in the presence of a hydrofluoric acid catalyst. Another aspect of this invention relates to the processing of HF alkylation hydrocarbon effluent initially with HF stripping so that subsequently recovered isobutane stripper overhead vapors will be HF-free and can then be compressed and used as additional heat exchange fluid prior to being recycled to the HF alkylation. This invention also relates to the use of HF-free, compressed isobutane stripper overhead vapors to reboil an HF separation zone such as an HF stripper. In another aspect, this invention relates to an alkylation process wherein compressed HF-free isobutane stripper overhead vapors are used to (1) reboil the HF stripper, (2) heat the inner heater on the isobutane stripper and (3) heat the depropanizer inner heater.
As is well known, hydrocarbon products may be produced by alkylation reactions involving the combination or condensation of two dissimilar hydrocarbon reactants in the presence of suitable catalytic agents. While various types of alkylate products may be obtained by employing various types of reactants, the alkylation of low boiling isoparaffins, such as isobutane and isopentane, with low boiling olefins, such as ethylene, propylene, the isomeric butenes, and the isomeric pentenes, for the production of various fuels has become of particular importance. Liquid hydrogen fluoride (hydrofluoric acid) has found favor as a catalyst in this type of reaction.
The alkylation of isobutane with olefins is representative of this type of reaction and has been commonly carried out by feeding isobutane and olefin feed stocks in the liquid state along with hydrofluoric acid to an alkylation reactor such as a riser reactor. The reaction product stream is then passed to various separation zones such as an HF stripper, an isobutane stripper and a propane stripper in order to recover the various components of the stream. The energy requirements for heating the various separation zones and streams are great and it would be desirable, due to the high cost of energy, to use an energy conserving alkylation process.
It is an object of this invention, therefore, to provide an improved alkylation process.
Another object of this invention is to utilize the available heat in an HF alkylation plant in a more efficient manner.
It is another object of this invention to cut down on the energy costs of an alkylation process.
Other aspects, objects, and advantages of the present invention will become apparent from a study of the disclosure, the appended claims, and the drawings.