Separation system for C4 hydrotreater effluent having reduced hydrocarbon loss

摘要

A hydrotreating process uses a separation section that reduces the loss of C4 and higher hydrocarbons through the use of a low hydrogen to hydrocarbon ratio in the reactor and the adsorptive removal of a majority of hydrogen sulfide from a liquid phase hydrotreater effluent. Sulfurous hydrocarbon feed is admixed with hydrogen to maintain a hydrogen to hydrocarbon ratio of less than 50 SCFB. The hydrogen and hydrocarbons are passed through a hydrotreater reactor to convert sulfur compounds to H2S. The hydrotreater effluent is cooled and after flashing of any excess hydrogen or light ends the cooled effluent is contacted with an adsorbent material for the removal of H2S. A hydrotreated hydrocarbon product is withdrawn from the adsorption section. The low hydrogen to hydrocarbon ratio permits the process to be used without the recycle of hydrogen thereby eliminating the need for separators and compressors that were formly used to recycle hydrogen to the hydrotreater. The elimination of the recycle and the low hydrogen to hydrocarbon ratio simplifies the flowscheme which can use a simple separator to flash light ends, hydrogen and some H2S from the hydrotreater effluent. This process thus eliminates the need for a stripping section that was formerly needed to remove light ends and hydrogen sulfide from the hydrotreated product. The adsorptive removal of the H2S and the limited venting of hydrogen allows essentially all of the hydrotreated product to be preserved. In most flowschemes H2S removal can be carried out in the adsorbers that are usually present for drying of the hydrotreated feed.