How is propane, made and obtained and used?

Nadia Crauswell: Propane is produced as a by-product of two other processes, natural gas processing and petroleum refining. The processing of natural gas involves removal of butane, propane and large amounts of ethane from the raw gas, in order to prevent condensation of these volatiles in natural gas pipelines. Additionally, oil refineries produce some propane as a by-product of cracking petroleum into gasoline or heating oil. The supply of propane cannot easily be adjusted to meet increased demand, because of the by-product nature of propane production. About 90% of U.S. propane is domestically produced. The United States imports about 10% of the propane consumed each year, with about 70% of that coming from Canada via pipeline and rail. The remaining 30% of imported propane comes to the United States from other sources via ocean transport.Propane is nontoxic; however, when abused as an inhalant it poses a mild asphyxiation risk through oxygen deprivation. Commercial pr! oducts contain hydrocarbons beyond propane, which may increase risk. Commonly stored under pressure at room temperature, propane and its mixtures expand and cool when released and may cause mild frostbite.The advantage of propane in cars is its liquid state at a moderate pressure. This allows fast refill times, affordable fuel tank construction, and ranges comparable to (though still less than) gasoline. Meanwhile it is noticeably cleaner (both in handling, and in combustion), results in less engine wear (due to carbon deposits) without diluting engine oil (often extending oil-change intervals), and until recently was a relative bargain in North America. Octane rating of propane is relatively high at 110. In the United States the propane fueling infrastructure is the most developed of all alternative vehicle fuels. Many converted vehicles have provisions for topping off from "barbecue bottles". Purpose-built vehicles are often in commercially owned fleets, and have private ! fueling facilities. A further saving for propane fuel vehicle ! operators, especially in fleets, is that pilferage is much more difficult than with gasoline or diesel fuels. It must be noted that LPG in cars does contain a mixture of butane, where in domestic cylinders it doesn't.Propane is generally stored and transported in steel cylinders as a liquid with a vapor space above the liquid. The vapor pressure in the cylinder is a function of temperature. When gaseous propane is drawn at a high rate, the latent heat of vaporisation required to create the gas will cause the bottle to cool. (This is why water often condenses on the sides of the bottle and then freezes). In addition, the lightweight, high-octane compounds vaporize before the heavier, low-octane ones. Thus the ignition properties change as the tank empties. For these reasons, the liquid is often withdrawn using a dip tube. Propane is used as fuel in furnaces for heat, in cooking, as a energy source for water heaters, laundry dryers, barbecues, portable stoves, and motor vehic! les. Propane remains a popular choice for barbecues and portable stoves because its low boiling point of âˆ'42 °C (âˆ'44 °F) makes it vaporize as soon as it is released from its pressurized container. Therefore, no carburetor or other vaporizing device is required; a simple metering nozzle suffices. Propane powers some locomotives, buses, forklifts, taxis and ice resurfacing machines and is used for heat and cooking in recreational vehicles and campers.Propane use is growing rapidly in non-industrialized areas of the world. Propane is replacing wood and other traditional fuel sources in such places, where it is now sometimes called "cooking gas". North American barbecue grills powered by propane cannot be used overseas. The "propane" sold overseas is actually a mixture of propane and butane. The warmer the country, the higher the butane content, commonly 50/50 and sometimes reaching 75% butane. Usage is calibrated to the different-sized nozzles found in non-U.S. grills. A! mericans who take their grills overseas â€" such as military personnel ! â€" can find U.S.-specification propane at AAFES military post exchanges.North American industries using propane include glass makers, brick kilns, poultry farms and other industries that need portable heat.In rural areas of North America, as well as northern Australia and some parts of southern India propane is used to heat livestock facilities, in grain dryers, and other heat-producing appliances. When used for heating or grain drying it is usually stored in a large, permanently placed cylinder which is recharged by a propane-delivery truck. As of 2000, 6.9 million American households use propane as their primary heating fuel....Show more

Letitia Bigelow: Propane comes from natural gas and petroleum wells.Raw natural gas contains about 90 percent methane, five percent propane, and five percent other gases. The propane is separated from the raw natural gas and the other gases at a natural gas processing plant. It is a three-carbon alkane with the molecular! formula C3H8, normally a gas, but compressible to a transportable liquid. It is commonly used as a fuel for engines, oxy-gas torches, barbecues, portable stoves and residential central heating. A mixture of propane and butane, used mainly as vehicle fuel, is commonly known as liquefied petroleum gas (LPG or LP gas). It may also contain small amounts of propylene and/or butylene. An odorant such as ethanethiol or thiophene is added so that people can easily smell the gas in case of a leak....Show more

Miguel Koczela: How Is Propane Made