Propane

Propane is an energy-rich gas, C3H8. It is one of the liquefied petroleum gases(LP-Gas or LPGs) that are found mixed with natural gas and oil. Propane and other liquefied gases, including ethane and butane, are separated from natural gas at natural gas processing plants, or from petroleum at refineries. The amount of propane produced from natural gas and from oil is about equal.

Propane naturally occurs as a gas. However, at higher pressure or lower temperatures, it becomes a liquid. Because propane is 270 times more compact as a liquid than as a gas, it is transported and stored in its liquid state. Propane becomes a gas again when a valve is opened to release it from its pressurized container. When returned to normal pressure, propane becomes a gas so that we can use it

1. What is Propane and History of Propane

Propane is a kissing cousin of natural gas and petroleum. Propane is usually found mixed with natural gas and petroleum deposits in rocks deep underground. Propane is called a fossil fuel because it was formed millions of years ago from the remains of tiny sea animals and plants.
When the plants and animals died, they sank to the bottom of the oceans where they were buried by layers of sand and silt. Over the years, the layers became thousands of feet thick. The layers were subjected to enormous heat and pressure, changing the energy-rich remains into petroleum and natural gas deposits. Eventually, pockets of these fossil fuels became trapped in rock layers much as a wet household sponge holds water.
Propane is just one of the many fossil fuels that are included in the liquefied petroleum (LP) gas family. Because propane is the type of LP-gas most commonly used in the United States, "propane" and "LP-gas" are often used synonymously. The chemical formula for propane is C3H8.
Just as water can change its physical state and become a liquid or a gas (steam vapor), so can propane. Under normal atmospheric pressure and temperature, propane is a gas. Under moderate pressure and/or lower temperatures, however, propane changes into a liquid. And that's the beauty of it.
Propane is easily stored as a liquid in pressurized tanks. (Think of the small tanks you see attached to a gas barbecue grill, for example.)
Propane takes up much less space in its liquid form. It is 270 times more compact in its liquid state than it is as a gas. A thousand gallon tank holding gaseous propane would provide a family enough cooking fuel for one week. A thousand gallon tank holding liquid propane would provide enough cooking fuel for almost ten years! Liquid propane instantly vaporizes into a gas when it is released from its tank to fuel propane gas appliances and equipment. Propane has been nicknamed the "portable gas" because it is easier to store and transport than natural gas.
Like its close cousin natural gas, propane is colorless and odorless. An odorant is added to propane (as it is to natural gas) to serve as a warning agent for escaping gas. And like all the fossil fuels---coal, natural gas, and petroleum--propane is a nonrenewable energy source.

History of Propane

Propane does not have a long history. It wasn't discovered until 1912 when people were trying to find a way to store gasoline. The problem with gasoline was that it evaporated when stored under normal conditions.
Dr. Walter Snelling, directing a series of experiments for the U.S. Bureau of Mines, discovered that several evaporating gases could be changed into liquids and stored at moderate pressure. The most plentiful of these gases was propane. Dr. Snelling developed a way to "bottle" the wet (liquid) gas. One year later, the commercial propane industry began heating American homes.
2. Producing and Transporting Propane
Propane comes from natural gas and petroleum wells. Fifty-five percent of the propane used in the United States is extracted from raw natural gas. (Raw natural gas is natural gas that hasn't been cleaned and processed yet.) Raw natural gas contains about 90 percent methane, five percent propane, and five percent other gases. The propane is separated from the other gases at a natural gas processing plant.
The remaining 45 percent is extracted from petroleum. Petroleum is separated into its various parts at a processing plant called a refinery.

HOW PROPANE IS USED

Although propane accounts for about 2 percent of all energy used in the United States, it has some very important uses. Propane is the most common source of energy in rural areas that do not have natural gas service. It is used for heating homes, heating water, cooking and refrigerating food, drying clothes, and fueling gas fireplaces and barbecue grills.

On farms, it is used to dry corn and power farm equipment and irrigation pumps. Businesses and industry use propane to run their fork lifts and other equipment. About 44 percent of propane is used by the chemical industry as a raw material for making plastics, nylon, and other materials. While only a small fraction of propane is used for transportation, it is the largest alternative transportation fuel in use today. Instead of gasoline, propane is often used to fuel fleets of vehicles used by school districts, government agencies, and taxicab companies. In recreational pursuits, hot air balloons use propane to heat the air that makes them rise.

GETTING PROPANE TO USERS

How does propane get to the people who use it? Propane usually goes by underground pipeline to terminals across the country. Railroads, barges, trucks, and supertankers also ship the propane to bulk distributors.

Local propane dealers come to the distributor's bulk plant to fill up their small tank trucks. These tank trucks, called "bobtails", deliver propane to large storage tanks that are outside homes. The average residential propane tank holds between 500 - 1,000 gallons of liquid fuel, and is refilled several times a year. People who use just a little propane - for a backyard barbecue, for example - bring their tanks to hardware stores to be filled or to be exchanged for full ones.

MORE ABOUT LIQUEFIED PETROLEUM GASES

Liquefied petroleum gases (LP-gases or LPGs) are mixtures of propane, ethane, butane and other gases that are produced at natural gas processing plants and refineries. Other plants, called fractionation plants, separate the liquids from each other.
LP-gases were discovered in 1912 when an American scientist, Dr. Walter Snelling, discovered that these gases could be changed into liquids and stored under moderate pressure. The LP-gas industry got its start shortly before World War I when a problem in the natural gas distribution process popped up. A section of the pipeline in one natural gas field ran under a cold stream, and the coldness led to a lot of liquids building up in the pipeline, sometimes to the point of blocking the entire pipeline. Soon, engineers figured out a solution: facilities were built to cool and compress natural gas, and to separate the gases that could be turned into liquids (including propane and butane).

ENVIRONMENTAL ISSUES

Propane is a non-renewable fossil fuel, like the natural gas and oil it is produced from. Like natural gas (methane), propane is colorless and odorless. Although propane is nontoxic and odorless, foul-smelling mercaptan is added to it to make gas leaks easy to detect. Propane is a clean burning fossil fuel, which is why it is often chosen to fuel indoor equipment such as fork lifts. Its clean burning properties and its portability also make it popular as an alternative transportation fuel. Propane-fueled engines produce much fewer emissions of carbon monoxide and hydrocarbons compared to gasoline engines. Like all fossil fuels, propane emits water vapor and carbon dioxide, a greenhouse gas.

The Propane Molecule

A three-carbon alkane, propane is sometimes derived from other petroleum products during oil or natural gas processing.
Chemical Formula: C3H8
http://en.wikipedia.org/wiki/Lewis_Structure When commonly sold as fuel, it is also known as liquified petroleum gas (LPG or LP gas) and is a mixture of propane with smaller amounts of propylene, butane and butylene, plus an ethyl mercaptan odorant to allow the normally odorless propane to be smelled. It is used as fuel in cooking on many barbecues and portable stoves and in motor vehicles. Propane powers some buses, forklifts, and taxies and is used for heat and cooking in recreational vehicles and campers. In many rural areas of the US, propane is also used in furnaces, water heaters, laundry driers, and other heat-producing appliances. Delivery trucks fill up large tanks that are permanently installed on the property (sometimes called pigs) or exchange bottles of propane.

Propane is the liquid petroleum gas (LPG) used to fuel hot air balloons. When handled properly it is a safe and efficient fuel. It is sometimes supplied in a mixture with other gases such as butane, butylene and propylene.
General Properties of Propane
1. Propane is a colourless, odourless and non-toxic gas. It is supplied commercially with an added odorant to assist detection by smell.

2. Propane boils at -42 degrees Celsius. At 15 degrees Celsius it has a storage pressure of 635 kPa.

3. Propane is stored as a liquid under pressure and will expand approximately 270 times to a vapour at normal temperatures and pressure
when released.

4. When the propane changes to a vapour it is possible to see the initial leak by the cooling effect of the leak, which causes condensation, and even freezing of the water vapour in the air. Not being able to see the effects of the leak after a short distance does not mean that the gas is not present in a potentially explosive mixture.

5. Propane is heavier than air, and may flow along the ground or through drains and will sink to the lowest level of the surroundings.

6. The flammability range of the gas is 1.6% to 9.5% by volume in air. A small proportion of the gas can therefore give rise to a flammable mixture.

7. Propane and other LPG gases are excellent solvents of petroleum and rubber products.

8. Propane and other LPG gases are generally non-corrosive to steel and copper alloys. Precautions against corrosion may be necessary if aluminium or aluminium alloys are used.

Refuelling Rules
1. Vehicles should be pointed into the wind, and the refueller must ensure that they are not blocked in.
2. LPG, by its rapid vaporisation and consequent lowering of temperature can cause severe frost burns. Protective clothing such as gloves, goggles and a long sleeved shirt should be worn when there is any possibility of contact with liquid LPG.
3. Before filling commences, the area shall be checked to ensure that there are no sources of ignition, i.e. smoking, naked lights or flames, running car engines, or mobile phones within 10 metres of the connections at either end of the transfer hose.
4. A check should be made to ensure that the test stamp on the cylinder is within the required ten-year test period. A cylinder, which does not have a current test inspection stamp, must not be filled.
5. A check should also be made for apparent damage or corrosion to the cylinder, and all valves and / or controls checked to ensure that they are in good working order with no leakage.
6. Cylinders must not be tilted during refuelling.
7. It is very important that cylinders are not overfilled, and that a vapour space is left at the top of the cylinder. This is achieved by closing the cylinder valve immediately LPG flows from the bleeder valve. Leaks
· Shut off any electrical equipment and leave off until vapour hazard is removed.
· If available, use the outside "EMERGENCY STOP" handles or buttons.
· No smoking or naked lights within 70 metres.
· Move people away from the area. Move upwind.
· Stop leaks if possible.
· If possible, separate the leaking container and position so that only gas escapes.
· Spray water to disperse the gas cloud.
· Prevent spillage where practical from spreading or entering underground drains by banking with sand or earth.
· Do not start engines and / or operate electrical equipment in the area.
· Inform the fire brigade, police and gas supplier.