Abstract: An improved Mehra process utilizes at least one and, if necessary, up to three gas extracting steps for processing a nitrogen-rich gas stream which can vary in composition from 3 to 75 mol. % nitrogen, the remainder being hydrocarbons, and from entirely dry to water saturated and from sweet to sour. The improved Mehra process provides up to three products, namely: nitrogen gas product, C.sub.1 -rich gas product and C.sub.2 + liquid product. The process effectively utilizes a physical solvent for extracting and upgrading the BTU value of a nitrogen-rich natural gas stream.

Abstract: A process is disclosed in which a preferential physical solvent selectively extracts and strips desirable C.sub.2 + hydrocarbons from a raw hydrocarbon gas stream which is fed into the midsection of an Extractor-Stripper (ES) column, the rich solvent produced from the bottom thereof being regenerated in a distillation column which produces a hydrocarbon gas liquid stream as product and a lean physical solvent for recycling to the top of the ES column. When certain operating conditions and product specifications necessitate operating the ES column bottoms at a temperature high enough to become relatively energy inefficient, a single-stage intermediate flashing vessel is provided for effectively removing undesirable hydrocarbons at a pressure consistent with the operating pressure of the distillation column. The separated overhead vapor stream from the flashing vessel contains all of the undesirable components along with some desirable hydrocarbons.

Abstract: The Mehra process, for selectively extracting C.sub.2 + hydrocarbons from a raw natural gas stream to produce a residue gas stream meeting pipeline specifications and a natural gas liquid product, is improved by providing a process for purifying the liquid product. This improved process comprises injecting a stream of methanol into the stream of flashed gases from at least the final flashing stage. The injection preferably occurs prior to condensing the flashed gases and must occur prior to reaching the temperature of hydrate formation. The natural gas liquid product from the demethanizing (stripping) column is then allowed to separate into two phases in a surge vessel. The lower layer of methanol/water/physical solvent is removed, the methanol is recovered for recycling to the flashed gases. The upper layer is decanted as purified natural gas liquid product which meets specifications for gumming compounds if the raw natural gas stream is entirely sweet.

Abstract: A stream of natural gas, which is rich in C.sub.5 + hydrocarbons and may be wet or dry or sweet or sour, is extracted in two stages with a physical solvent. In the first stage, a major portion of the solvent, containing up to an equilibrium amount of C.sub.5 + hydrocarbons, removes substantially all of the water and the C.sub.2 + hydrocarbons. In the second stage, the partially stripped natural gas is countercurrently extracted with a lean-and-dry minor portion of the solvent which contains less than 1% by weight of water and less than 1% by volume of hydrocarbons. The residue natural gas, which is then sent to a pipeline, contains less than 7 pounds of water per million standard cubic feet. The rich solvent is flashed to atmospheric pressure in at least two stages, forming a methane-rich vapor portion which is suitably recycled to the first extraction, a methane-poor vapor portion, and a flashed solvent containing up to equilibrium amounts of C.sub.5 + hydrocarbons.

Abstract: A continuous process is described for treating a raw inlet natural gas stream to produce: (a) a liquid C.sub.2 + hydrocarbon product having a composition that is selectively adjustable to substantially any selected degree, as the market price for each individual hydrocarbon liquid falls below its fuel price, by selectively rejecting a consecutive molecular weight string of C.sub.2 -C.sub.4 components and then returning the desirable price component or components to the liquid products stream and (b) a sweet, dry residue natural gas stream of pipeline quality which includes the rejected C.sub.2, C.sub.3, and/or C.sub.4 hydrocarbon components.

Abstract: A continuous process for selective countercurrent extraction of C.sub.2 + hydrocarbons from a natural gas stream with a physical solvent while at pipeline pressures to produce a residue natural gas stream meeting pipeline specifications and a liquid hydrocarbon product having a composition which can be readily adjusted to any selected degree in accordance with market conditions so that profitability of the extraction operation can be maximized at all times. The rich solvent is let down in pressure through successive flashing stages to produce a liquid product, and the stripped solvent is recirculated to the extraction step. The versatility of the process is achieved by using the following steps, in order of importance: (1) selectively varying the flow rate of the solvent with respect to the flow rate of the natural gas stream; (2) selectively varying the flashing pressure for one or more successive flashing stages; (3) recycling the flashed C.sub.

Abstract: A sweet natural gas stream is stripped of water and hydrocarbon components heavier than methane to substantially any selected degree by countercurrent extraction with polyethylene glycol dimethyl ether while at pipeline pressures. The stripped natural gas meets pipeline specifications. The rich polyethylene glycol dimethyl ether is let down in pressure through selected successive stages which respectively isolate fractions that are rich in ethane, propane, butanes, and hydrocarbons heavier than butane. Lastly, waste water is removed from the solvent to regenerate the polyethylene glycol dimethyl ether. The separated gas streams of ethane, propane, butanes, and hydrocarbons heavier than butanes are individually compressed, combined, condensed and cooled to form a natural gas liquid stream, suitable for pipeline shipment.

Abstract: This invention provides a process for separating 1,3-butadiene from a C.sub.4 -hydrocarbon mixture which contains C.sub.4 -alkyne components.In one embodiment, the invention involves a first step hydrogenation procedure for selectively hydrogenating the C.sub.4 -alkyne components, and a second step extractive distillation procedure for separating out a 1,3-butadiene rich selective solvent extract phase.