Process and apparatus for processing a hydrocarbon gas stream

#The present invention is directed to a process and apparatus for processing a mixed hydrocarbon gas stream such as natural gas, refinery gas, and synthetic gas streams. More particularly, the present process and apparatus provide an enhanced and sharper separation of hydrocarbon mid-components (i.e., C3 and/or C4 hydrocarbons) from a mixed hydrocarbon gas stream. The present invention further provides the capability to direct a desired portion of the mid-components to either a gaseous product comprising the majority of C1, C2, hydrocarbons or a liquid product comprising the majority of C5 and C6+ hydrocarbons, or a chosen amount to both gas and liquid products in order to maximize profitability at any time.

#Raw or mixed hydrocarbon gas consists primarily of methane (CH4) but also includes heavier gaseous hydrocarbons such as ethane (C2H6), propane (C3H8), butanes (C4H10), pentanes (C5H12), higher molecular weight hydrocarbons (C6+), and other hydrocarbon species and non-hydrocarbons associated with the raw gas source.

#The relative amount of the heavier gaseous hydrocarbons, or richness, can be expressed in terms of gallons per mcf (thousand cubic feet), abbreviated as GPM. In this embodiment, GPM includes all hydrocarbon components heavier than methane and represents the total volume, in liquid gallons, contained in one thousand cubic feet of a particular gas at standard conditions.

#Referring to the drawings wherein like reference numerals indicate similar parts throughout the several views, several aspects of the present invention are illustrated by way of example, and not by way of limitation, in detail in the following figures. It is understood that the drawings provided herein are for illustration purposes only and are not necessarily drawn to scale.

#FIG. 1 is a schematic depiction of a conventional refrigeration process and apparatus of the prior art.

#FIG. 2 is a schematic depiction of one embodiment of the process and apparatus of the present invention.

#The detailed description set forth below in connection with the appended drawings is intended as a description of various embodiments of the present invention and is not intended to represent the only embodiments contemplated by the inventor. The detailed description includes specific details for the purpose of providing a comprehensive understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without these specific details.

#The purpose of gas processing such as natural gas processing is to convert raw natural gas into sales gas and HGL which can be delivered to end user markets, In other words, gas processing conditions gas to commercial specifications, e.g., hydrocarbon dew point (HCDP), water content, heating value, and other qualities as specified by a particular gas transmission or distribution company. Further, gas processing allows for the recovery of higher value liquefied products such as C2, C3, C4, and C5+ hydrocarbons, processed by one or more fractionation steps to meet commercial specifications such as hydrocarbon component content, vapor pressure, and density. As used herein “rich gas” means a gas which contains heavier hydrocarbons and is typically between temperatures of 30° F. and 120° F., and is typically provided at pressures between 200 Psig and 1000 Psig.

#FIG. 2 shows one embodiment of a hydrocarbon gas processing plant of the present invention. In particular, rich gas feed 210 is combined with recycle gas (stream 227) to produce stream 211, which stream 211 can be further processed in at least one heat exchanger. In the embodiment shown in FIG. 2, stream 211 is only fed to a single heat exchanger as stream 212. Stream 212 is fed into a gas/gas heat exchanger 202 and is cooled in heat exchanger 202 by heat exchange with cool stream 218. It is understood, however, that stream 212 can be cooled in one or more of any cooling device, for example, such as a cooling tower, evaporative cooler, water chiller, gas chiller, waste heat exchanger, Joule-Thompson expansion valve, and the like.