economically, more elaborate techniques are being developed. For in situ mining, the steam can be injected into the drill holes to heat up the sands and fluidize the oil. Other processes involve controlled ignition of the tar sands and air pressure to drive the freed oil toward the production holes.
Table 3.3 Primary distillation fractions from crude petroleum
Fraction Boiling point range (C) Composition Uses
Gas up to 25 C1C4 Petrochemical fuel
Petroleum ether 25–60 C5C7 Solvent
Gasoline 0–17 C6C11 Fuel for ICE
Kerosene 17–220 C11C13 Jet fuel
Heating oil 220–250 C13C16 Fuel oil
Lubricating oils 350–400 C16C20 Lubricants and grease
Paraffins 400–500 C20+ Candles
Asphalts >500 C30+ Road surfaces
Table 3.4 Consumption of petroleum products in Canada (in thousands m3/day, IEA 2006)
Name 1983 1990 1994 2005
Motor gasoline 91.0 103.5 109.1 111.5
Aviation turbo fuel 10.7 15.7 13.0 19.0
Diesel fuel 38.4 46.2 49.8 9.3
Light fuel oil 23.5 17.6 15.5 86.4
Heavy fuel oil 25.2 29.1 19.8 –
Lubricating oil 2.6 2.5 2.4 –
Lubricating grease 0.10 0.083 .062 –
Total domestic demand 236.1 267.3 267.3 372.3
Fig. 3.5 Distillation, the first step in oil refining, separates crude oil into a number of products. First, the crude oil is heated by being pumped through pipes in a furnace. The resulting mixture of vapors and liquid goes to a tower where the vapors rise, condense on trays, and are drawn off through pipes as products. The part of the crude that does not boil in the first distillation step is reheated and distilled in a vacuum. Again, vapors rise, condense, and are drawn off as products. Some of the very heavy oil, which does not boil even under the reduced pressure, is used in factories and ships or made into asphalt
and diesel fuels are discussed in Chap.4, and lubrication oils and greases are discussed in Chap.8.
Aviation fuel has not changed much since its early use in the jet engine. The stability of the fuel has improved, and specific corrosion inhibitors, antioxidants, and antistatic additives have been included in formulations. Combustion in a gas turbine is continuous in contrast to the intermittent combustion of the ICE, and thus, the “antiknock” quality of the fuel is not important. The thrust of the engine is generated by the energy released during the combustion process which takes place at constant pressure.
The heat generated thus causes an increase in volume and gas flow to the turbine blades. An important restriction is the material of construction which must withstand the high temperatures developed.
The jet fuel must have a low tendency to deposit carbon which can lead to high thermal radiation causing damage to the engine components. Likewise, sulfur in fuel must be very low since it enhances carbon deposition and corrosion. These factors and the physical properties require the fuel to have a low freezing point and be free of wax which, at low temperatures, can precipitate out and clog fuel lines. At high altitudes, temperatures as low as 50C are normal, and 60C is the specified maximum freezing point for aviation fuel. Similarly water must be absent. Anti-icing additives are present in the fuel to ensure that at low temperatures, any water which does come out of the fuel will not form large ice crystals which can clog the fuel lines.
Aviation fuel (avogas), which is designed for use in piston engines, still contains lead [0.53 mL of tetraethyl lead (TEL) per liter of fuel]. One hazard, tolerable on the ground but deadly in the air, is the vapor lock, and special care is taken to ensure that this does not happen. Hence, automotive fuel, though often equivalent to avogas but half the cost, cannot be used as a substitute.
Oil seepages on the surface were the early sources of crude oil. Kerosene was initially used primarily for lamps. Today, it is generally used for heating as space heaters, where a catalytic surface maintains a hot radiating source of heat. In countries where electricity is expensive, e.g., Japan and Israel, it is not uncommon to see such appliance heaters in homes and offices. Such open flames are sufficiently hot to produce NOxas well as some hydrocarbon products which are readily detected by their odor. The main characteristics of a domestic grade of kerosene, which burns on a catalytic surface, are low sulfur and controlled smoke point and volatility.
Coal for heating was replaced by oil during the 1940s, and oil was replaced by natural gas soon after. The natural gas pipeline, however, cannot reach every home, and as a result, fuel oil as well as bottled gas (propane) is still used in many locations. The fuel oil differs only slightly from diesel fuel, and because its ignition property is not important, it usually contains more aromatics and olefins than diesel fuel. The most important property of fuel oil is its storage stability, and additives prevent sludge formation. Viscosity is another controlled characteristic of the fuel because the size of the droplets in the burning spray is critical for efficient combustion.
World production of petroleum wax is about 2 Mt/year. The major product is candles (about 25%), replacing beeswax and tallow used a century ago. The present applications include coating on cartons for juice, milk, and other food products and for waterproofing and preserving freshness. The major concern with the use of wax or any petroleum product for food and edibles is the need to have it completely free of the polynuclear aromatic hydrocarbons (PAH). Trace amounts have been detected in liquid petroleum used for oral consumption. However, our daily diet usually contains much more PAH than what is in a spoonful of liquid petroleum taken occasionally. Bitumen or asphalt is the black or dark brown solid residues from the distillation of crude oil. Naturally occurring bitumen is found in the USA, Europe, and other parts of the world. Commercial bitumen comes in various degrees of hardness and softens at a temperature of 25–135C. When air is blown into molten bitumen, oxidation or dehydrogenation occurs, and the material becomes rubbery and more penetrating than the regular grades. Bitumens can be applied as a melt, emulsion, or from a solution.
The application of bitumen to roads usually involves the inclusion of sand and gravel, and in North America, this is normally referred to as asphalt.
48 3 Crude Oil
The inclusion of other aggregates which have been tested and added for various road systems includes sulfur, shredded discarded tires, limestone (<200 mesh), and crushed concrete. Other applications of bitumen are in roofing, flooring, and as an anticorrosion coating on surfaces exposed to corrosive atmosphere, aggressive soils, and chemicals. The main advantage of bitumen, in many of its applications, is that it is cheaper than alternative materials. The world production of bitumen in 1993 was about 17 Mt.
The reserves of oil are limited, and its uses as a fuel for its heat value may eventually become a luxury which few will be able to afford. The petrochemical industry supplies the plastics and resins we use daily, the synthetic fiber for our clothes, and the detergents for our soaps and washings, as well as the chemicals and solvents for industrial use. World petrochemicals amount to about 1/7 of total steel production and about seven times the aluminum produced by weight.