Gaseous fuels in common use are liquefied petroleum gases LPG Natural gas

Gaseous fuels in common use are liquefied petroleum

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Gaseous fuels in common use are liquefied petroleum gases (LPG), Natural gas, producer gas, blast furnace gas, coke oven gas etc. The calorific value of gaseous fuel is expressed in Kilocalories per normal cubic meter (kCal/Nm 3 ) i.e. at normal temperature (20°C) and pressure (760 mm Hg). Calorific Value Since most gas combustion appliances cannot utlilize the heat content of the water vapour, gross calorific value is of little interest. Fuel should be compared based on the net calorific value. This is especially true for natural gas, since increased hydrogen content results in high water forma- tion during combustion. Lignite Bituminous Bituminous Coal Indonesian Coal coal (Sample I) (Sample II) Moisture (%) 50 5.98 4.39 9.43 Ash (%) 10.41* 38.65 47.86 13.99 Volatile matter (%) 47.76* 20.70 17.97 29.79 Fixed carbon (%) 41.83* 34.69 29.78 46.79 TABLE 1.10 PROXIMATE ANALYSIS OF TYPICAL COAL *Dry Basis
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Typical physical and chemical properties of various gaseous fuels are given in Table 1.12. 1. Fuels and Combustion 13 Bureau of Energy Efficiency TABLE 1.12 TYPICAL PHYSICAL AND CHEMICAL PROPERTIES OF VARIOUS GASEOUS FUELS. Fuel Gas Relative Higher Heating Air/Fuel ratio- Flame Temp. Flame Density Value kCal/Nm 3 m 3 of air to °C Speed m/s m 3 of Fuel Natural Gas 0.6 9350 10 1954 0.290 Propane 1.52 22200 25 1967 0.460 Butane 1.96 28500 32 1973 0.870 LPG LPG is a predominant mixture of propane and Butane with a small percentage of unsaturates (Propylene and Butylene) and some lighter C 2 as well as heavier C 5 fractions. Included in the LPG range are propane (C 3 H 8 ), Propylene(C 3 H 6 ), normal and iso-butane (C 4 H 10 ) and Butylene(C 4 H 8 ). LPG may be defined as those hydrocarbons, which are gaseous at normal atmospheric pressure, but may be condensed to the liquid state at normal temperature, by the application of moderate pressures. Although they are normally used as gases, they are stored and transported as liquids under pressure for convenience and ease of handling. Liquid LPG evaporates to produce about 250 times volume of gas. LPG vapour is denser than air: butane is about twice as heavy as air and propane about one and a half times as heavy as air. Consequently, the vapour may flow along the ground and into drains sinking to the lowest level of the surroundings and be ignited at a considerable distance from the source of leakage. In still air vapour will disperse slowly. Escape of even small quan- tities of the liquefied gas can give rise to large volumes of vapour / air mixture and thus cause considerable hazard. To aid in the detection of atmospheric leaks, all LPG’s are required to be odorized. There should be adequate ground level ventilation where LPG is stored. For this very reason LPG cylinders should not be stored in cellars or basements, which have no ventilation at ground level. Natural Gas Methane is the main constituent of Natural gas and accounting for about 95% of the total vol- ume. Other components are: Ethane, Propane, Butane, Pentane, Nitrogen, Carbon Dioxide, and traces of other gases. Very small amounts of sulphur compounds are also present. Since
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