Combustion of natural gas

Natural gas is attractive as a fuel ia many appHcatioas because of its relatively clean burning characteristics and low air pollution (qv) potential compared to other fossil fuels. Combustion of natural gas iavolves mixing with air or oxygen and igniting the mixture. The overall combustion process does not iavolve particulate combustion or the vaporization of Hquid droplets. With proper burner design and operation, the combustion of natural gas is essentially complete. No unbumed hydrocarbon or carbon monoxide is present ia the products of combustioa. 

Products of Combustion For lean mixtures, the products of combustion (POC) of a sulfur-free fuel consist of carbon dioxide, water vapor, nitrogen, oxygen, and possible small amounts of carbon monoxide and unburned hydrocarbon species. Figure 27-12 shows the effect of fuel-air ratio on the flue gas composition resulting from the combustion of natural gas. In the case of solid and liquid fuels, the... 

Combustion of natural gas is a ehemieal reaetion that oeeurs between earbon, or hydrogen, and oxygen. Heat is given off as the reaetion takes plaee. The produets of eombustion are earbon dioxide and water. The reaetion is... 

Traditionally, the steam reforming reactor has a tubular design in which vertical tubes, loaded with catalyst, are surrounded by furnaces to supply the heat required for the strongly endothermic process, see Fig. 8.2. Combustion of natural gas supplies the heat to the tubes. 

Heat Release Rate From Fuel Gas. The fuel gas used in these tests was a mixture of natural gas supplied by the local gas company. This gas mixture contains approximately 90 percent methane and small fractions of ethane, propane, butane, C02, and nitrogen, as analyzed by Brenden and Chamberlain (6). Although composition of the gas changes with time, the changes were small in our case. A statistical sample of gross heat of combustion of fuel gas over several months showed a coefficient of variation of 0.7 percent. Also, the gross heat of combustion of natural gas reported by the gas company on the day of the test did not vary significantly from test to test. Thus, we assumed that the net heat of combustion was constant. 

Thermatomic An early process for making carbon black by the incomplete combustion of natural gas. Operated in the 1920s and 1930s by the Thermatomic Carbon Company, Pittsburgh. 

Carbon black (soot). It is obtained by the incomplete combustion of natural gas or liquid hydrocarbons. The particle size of carbon black is very small its applications are mainly in rubber industry (to strengthen and reinforce rubber) and also as a pigment in the preparation of inks, etc. 

Observe the combustion of natural gas in a Bunsen burner. Adjust the colour of the flame by varying the quantity of oxygen admitted to the burner. How does the colour depend on the quantity of oxygen ... 

Acenaphthene was detected in a diesel-powered medium duty truck exhaust at an emission rate of 19.3 pg/km (Schauer et ah, 1999) and is a component in cigarette smoke. Acenaphthene was detected In soot generated from underventilated combustion of natural gas doped with 3 mole % toluene (Tolocka and Miller, 1995). 

Fluorene was detected in soot generated from underventilated combustion of natural gas doped with toluene (3 mole %) (Tolocka and Miller, 1995). 

Production of ammonia (NH ) Anhydrous (dry) ammonia is the fifth most produced industrial compound. The Haber-Bosch process uses steam on hot coke, which is mostly used in South Africa. In the United States, it is mostly produced from partial combustion of natural gas (methane) or by combining several gases using steam. Other methods use coke-oven gas, refinery gas (mostly methane), or even solar energy. Ammonia is toxic if inhaled and has a high pH value when mixed with water (hydration) to form ammonium hydroxide (NH OH), which has many uses, including as a household cleaner. Ammonia forms many compounds, including ammonium nitrate in fertilizer, rocket fuel, and explosives. Ammonia is also explosive when mixed with mercury or silver or when mixed as part of nitrocellulose. 

Recent studies have addressed the combustion of natural gas with pure oxygen, highly diluted with exhaust gases (CO2 and H2O) in order to mitigate both NO and CO2 emissions from power plants. The so-called oxy-fuel combustion includes an air separation unit, which delivers O2 to the catalytic stage, where it is mixed with natural gas and the exhaust recycle stream. An example is the Advanced Zero Emission GT, first jointly studied by Norsk Hydro and ABB Alstom Power [28-31]. 

CO2 also is derived from synthesis gas which is a mixture of CO, CO2, H2 and N2 from air obtained by steam reforming. Carbon dioxide also is obtained by combustion of natural gas ... 

The combustion of natural gas, methane, to produce heat can be summarized in the following reaction ... 

The combustion of natural gas (mainly CH4) in air is a spontaneous, exothermic reaction. 

We caution the reader that applying Carnot s analysis is based on the assumptions that the heat is available at temperature T and that the heat reservoir is infinite. This means that if we use the adiabatic flame temperature for T, we will end up with a maximum attainable efficiency, since the exchange of heat will inevitably lead to a reduction in the temperature of the reservoir. From our analysis, it is not clear whether we used an adiabatic flame temperature [11]. Note that the adiabatic temperature is the highest temperature that can be reached by the system if all the heat generated is used to elevate the flame temperature. However, we can safely state that at least 30% of the maximum work potential has been lost. We will return to this subtle point at a later stage, when we examine the combustion of natural gas. 

Currently, global hydrogen production is 48% from natural gas, 30% from oil, and 18% from coal water electrolysis accounts for only 4%. The distribution of production reflects the effects of thermodynamic constraints on economic choices of the four processes for obtaining hydrogen, partial combustion of natural gas in a natural gas combined cycle power plant offers the most efficient chemical pathway and the greatest off-take of usable heat... 

Carbon black. This material is also nearly pure carbon and is produced by the incomplete combustion of natural gas. This process is exceedingly wasteful. Although burning 1000 ft3 of natural gas should theoretically yield 30 lb of carbon black, a yield of only about 1.5 lb is ordinarily obtained. This finely divided variety of carbon is used in very large quantities as a filler in the manufacture of automobile tires and other rubber goods. Carbon black is also used in the manufacture of printing inks and certain types of lacquers. 

Partial combustion of natural gas or oil with pure oxygen ... 

Continental dust flux is the main natural source of chromium in the atmosphere volcanic dust and gas flux are minor natural sources of chromium in the atmosphere (Fishbein 1981). Chromium is released into the atmosphere mainly by anthropogenic stationary point sources, including industrial, commercial, and residential fuel combustion, via the combustion of natural gas, oil, and coal. Other important anthropogenic stationary point sources of chromium emission to the atmosphere are metal industries. It... 

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