About Natural Gas in Brief
Natural gas is natural mixture of hydrocarbons and other gases and is very often
obtainable in porous formations of the earth's crust together with crude oil. It is
composed mainly of methane and other hydrocarbons and smaller contents of chemical
elements and compounds such as N2, CO2, H2S, Hg, O and H2O.
The commercial natural gas is mainly composed of 80-95% of methane and that is why it is
often called methane, the chemical formula of which is CH4.
Free natural gas is obtained from gas and gas-oil deposits by drilling into the earth's
crust to depths of more than 1000 meters where the deposits old for hundred thousands of
years are situated.
Natural Gas Quality According to Regulations
After natural gas has been pumped to the earth surface, it is cleaned from admixtures such
as water, other gases, oil rests and mechanical impurities in order to be within the
limits of the quality prescribed.
After cleaning, natural gas is transported through gas pipelines of high diameters, which
comprise compressor stations, storage facilities, metering and regulation stations, to the
take-over stations, and then through gas distribution network to the end users.
The cleaned natural gas is lighter than air, without color, odor and taste. For the safety
reasons, natural gas is odorized in the distribution system before it reaches the end
users. The odorization means that some admixture having a recognizable odor is added to
natural gas.
Combustion of Natural Gas
Approximately 2 m3 of oxygen are needed for complete combustion of 1 m3 of natural gas.
Natural gas is burnt without smoke and soot and no ash is produced. Further, there are
neither sulfur dioxide nor carbon monoxide in the combustion gases so that combustion does
not pollute the air.
Basic Thermo energetic Characteristics of Natural Gas
Depending on the natural gas quality, the basic thermo energetic characteristics of
natural gas range within the following limits:
| Wobbe´s index |
 |
W = 44.6 to 54.0 MJ/m3 |
| High calorific value: |
|
Hg = 30.2 to 47.2 MJ/ m3 |
| Low calorific value: |
|
Hd = 27.2 do 42.5 MJ/ m3 |
| Relative density: |
|
d = 0.55 to 0.75 kg/N m3 |
| Flash point: |
|
T = 595 to 640 oC |
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