there is no premix due to the high-level O 2 (>90%), which is extremely reactive. By
this type of enrichment, an overall improvement in the combustion process is
achieved, despite the higher operating costs (Baukal 2013).
3.3 Fuel Supply
Most industrial combustion processes require large amounts of energy, which is
commonly generated by the burning of fossil fuels. These fuels are composed of
hydrocarbons and sulfur, which readily combine with oxygen to produce a particular compound, and release a rather large amount of heat (Cengel 2003). Table 2
shows the main fuels (solids, liquids, and gaseous) with different heating value,
oxygen supply, and estimated CO 2 emissions. For burning of 1 kg of natural gas,
for example, one of the most commonly used gaseous fuels in combustion, it is
necessary to provide about 2.11 kg of oxygen, which emits an average of 2.63 kg
of CO 2 and presents potential energy of about 47 MJ/kg. The oxygen supply ranges
from 2.00 to 3.73 kg; i.e., the required amount of O 2 can be almost 4 times the
amount of fuel burned.
On the other hand, the use of oxygen-enrichment systems, besides improving the
combustion efficiency, reduces energy loss and also increases fuel economy,
depending on the exhaust gas temperature and the percentage of oxygen in the
combustion air (ITP 2005). According to the US Department of Energy and
the Industrial Heating Equipment Association (IHEA), the conversion to
oxygen-enriched combustion is followed by an increase in furnace temperature and
Fig. 1 Scheme of oxygen-enrichment methods in oxycombustion systems. a premix enrichment
with air; b air/fuel flame (O 2 lancing); c air/oxygen/fuel combustion; and d oxyfuel combustion
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this type of enrichment, an overall improvement in the combustion process is
achieved, despite the higher operating costs (Baukal 2013).
3.3 Fuel Supply
Most industrial combustion processes require large amounts of energy, which is
commonly generated by the burning of fossil fuels. These fuels are composed of
hydrocarbons and sulfur, which readily combine with oxygen to produce a particular compound, and release a rather large amount of heat (Cengel 2003). Table 2
shows the main fuels (solids, liquids, and gaseous) with different heating value,
oxygen supply, and estimated CO 2 emissions. For burning of 1 kg of natural gas,
for example, one of the most commonly used gaseous fuels in combustion, it is
necessary to provide about 2.11 kg of oxygen, which emits an average of 2.63 kg
of CO 2 and presents potential energy of about 47 MJ/kg. The oxygen supply ranges
from 2.00 to 3.73 kg; i.e., the required amount of O 2 can be almost 4 times the
amount of fuel burned.
On the other hand, the use of oxygen-enrichment systems, besides improving the
combustion efficiency, reduces energy loss and also increases fuel economy,
depending on the exhaust gas temperature and the percentage of oxygen in the
combustion air (ITP 2005). According to the US Department of Energy and
the Industrial Heating Equipment Association (IHEA), the conversion to
oxygen-enriched combustion is followed by an increase in furnace temperature and
Fig. 1 Scheme of oxygen-enrichment methods in oxycombustion systems. a premix enrichment
with air; b air/fuel flame (O 2 lancing); c air/oxygen/fuel combustion; and d oxyfuel combustion
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277