Processing of Natural Gas

CIM Bulletin, 1958

The economical processing of wet and sour natural gas presents a problem due to the seasonal demand for natural gas. The plants must be sized to handle the peak loads but may only operate at half capacity on the average, in which case the sales value of sulphur and hydrocarbon liquid by-products cannot support the operating and capital costs of the plant. This must result in an increased price for the gas. This problem was solved by Pacific Petroleums and Westcoast Transmission in the design of their pipeline and plant facilities now operating in the Peace River area, where there are both wet and dry gas fields. By .building a plant to process sufficient wet gas to provide the base load requirement, and by drawing on the dry gas fields for peak loads, an optimum economic operation was possible. The sulphur, L.P.G., and gasoline produced not only are able to support the operating and capital costs of the processing plant, but were instrumental in the sharp drop in retail prices of these commodities in the area. The sour gas and condensate is gathered from the fields in the area and transmitted in a two-phase gathering system to the gas processing plant at Taylor, B.C. The condensate is knocked out in inlet scrubbers. Hydrogen sulphide and carbon di ox 'de are removed in an amine scrubbing unit. The hydrogen sulphide is stripped from the amine and is sent to the Jefferson Lake Sulphur Company's plant; which produces sulphur by the partial oxidati on of the hydrogen sulphide. The natural gas, now sweet, is processed in an absorption unit to recover additional liquids, before being dehydrated to remove water. It is then sent to Westcoast's main c8mpression station. The condensate recovered in the inlet scrubber s and the liquid recovered in the absorption unit are fractionated to remove fuel gas, used in the plant, and to produce propane, butane, and naphtha. The propane and butane are scrubbed with caustic soda to remove hydrogen sulphide. The naphtha is treated with hydrogen in a unifier unit to remove sulphur compounds completely, and is split into a light and heavy naphtha. The heavy naphtha is .catalytically reformed to produce a highoctane blending- component. These fractions are blended with components produced from crude oil at the Dawson Creek refinery to produce a high-quality balanced gasoline with special attention being paid to volatility for ease of starting, warm up, and engine cleanliness, and octane for power and performance.
Keywords: amine, butane, hydrogen sulphide, naphtha, natural gas, sour gas, Hydrocarbons, hydrogen sulphide, Natural gas, Pipeline, Pipelines, Plants, Processing, Scrubbers, sulphur