Combustion for the Production of Energy

Cianpiero Croppi, Cinzia Cristiani, Alessandra Beretta, and Pio Forzatti 

In recent decades, catalytic combustion has been explored as a primary control method for the production ofheat and energy with two main goals (i) to achieve ultra-low emissions of NO, CO and unburned hydrocarbons (UHCs) and (ii) to obtain stable combustion under conditions not allowed by conventional methods. 

Catalytic combustion has been commercially demonstrated to reduce NO.. emissions to below 3 ppm while keeping CO and UHC emissions below 10 ppm without the need for expensive exhaust clean-up systems. In addition, a catalytic combustor reduces typical DLN problems such as risk of blow-out and flame instability. Also, the economic advantage of primary methods including catalytic combustion as opposed to secondary clean-up measures (SCR and SCONOx) has recently been assessed [1]. 

The potential of catalytic combustion has been recognized for more than 30 years, but only recently has this technology been proven to be commercially viable and finally commercialized, although to a limited level. 

Catalysis for Sustainable Energy Production. Edited by P. Barbaro and C. Bianchini Copyright 2009 WILEY-VCH Verlag GmbH, Co. KGaA, Weinheim ISBN 978-3-527-32O95-O 

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Forzatti, P. and Groppi, G. Catalytic combustion for the production of energy. Gatal. Today 1999, 54, 165-180. 

Carbon dioxide is considered to be an inert molecule since, with water, it is the end product of any combustion process, including biological cellular oxidation reactions. Although it is produced by all living organisms, whether animal or vegetable (for example, an adult man emits about 0.9kg C02 per day), by far the main source of C02 is the combustion of fossil carbon (coal, oil, gas) used for the production of energy. 

The uranium is consumed in the fission reaction. Energy generation by burning fossil fuels consumes fossil fuel chemicals and converts them to harmful combustion products. Nuclear reactors "bum" uranium and convert it to harmful fission products. Unlike fossil fuel materials, uranium has little other use than for the production of energy, like fossil fuels, there is a finite supply of the minerals used to produce the uranium for the fuel cycle. The worldwide amount of potential energy available by use of the burner reactor cycle is similar to that available from oil. If used at a high level the supplies of burner reactor uranium could be depleted in the middle of the next century. 

The combustion of fossil fuels for the production of energy introduces numerous metals into the atmosphere and subsequently into sods, rivers, and oceans. Coal contains the degraded matter of fossil plants. Crude oil is a thermal product of the kerogen and lipid fraction in residues from microorganisms preserved in sediments. The latter is usually perfectly separated from the silicates of the host rocks whereas coal still contains a minor fraction of the interlayered sediments. 

Flame or Partial Combustion Processes. In the combustion or flame processes, the necessary energy is imparted to the feedstock by the partial combustion of the hydrocarbon feed (one-stage process), or by the combustion of residual gas, or any other suitable fuel, and subsequent injection of the cracking stock into the hot combustion gases (two-stage process). A detailed discussion of the kinetics for the pyrolysis of methane for the production of acetylene by partial oxidation, and some conclusions as to reaction mechanism have been given (12). 

When one considers the potential high-energy release on rupture of a carborane unit, together with the thermodynamic stability of combustion products, it is hardly surprising that there is a body of literature that reports on the use of carbo-ranes within propellant compositions. Their use in energetic applications is to be expected when the enthalpy of formation (AH/) data for the products of combustion for boron are compared to those of carbon. Thermodynamic data for the enthalpy of formation of o-carborane and of typical boron and carbon combustion products is shown in Table 4. Measurements of the standard enthalpy of combustion32 for crystalline samples of ortho-carborane show that complete combustion is a highly exothermic reaction, AH = — 8994 KJmol. ... 

However, all saturated hydrocarbons are attacked by oxygen at elevated temperatures and, if oxygen is in excess, complete combustion to carbon dioxide and water occurs. Vast quantities of hydrocarbons from petroleum are utilized as fuels for the production of heat and power by combustion, although it is becoming quite clear that few of the nations of the world are going to continue to satisfy their needs (or desires) for energy thiough use of petroleum the way it has been possible in the past. 

The enhanced, direct fixation of C02 into fast-growing biomasses might contribute towards reducing its accumulation in the atmosphere, under non-natural conditions. Such an approach could be used for the production of chemicals and energy (e.g., conversion into gaseous and liquid fuels, rather than direct combustion of the solid biomass), with beneficial effects on reducing C02 emissions and accumulation in the atmosphere. The potential of biomass as a possible substitute for fossil fuels in the USA is shown in Figure 1.7. 

A nuclear reactor is a device in which nuclear chain reactions are initiated, controlled, and sustained at a steady rate. Nuclear reactors are used for many purposes, but the most significant current uses are for the generation of electrical power and for the production of plutonium for use in nuclear weapons. Currently, all commercial nuclear reactors are based on nuclear fission. The amount of energy released by one kg 235U is equal to the energy from the combustion of 3000 tons of coal or the energy from an explosion of 20,000 tons of TNT (Trinitrotoluene, called commonly dynamite). 

The vigorous combustion of phosphine produces orthophosphoric acid. A combustion with the production of 85 per cent, of this acid gave +311 calories3 at constant pressure. Values calculated for the heat of formation of gaseous phosphine are -11-6 Cals.,4,5 -9-1 Cals.,6 and -5-8 Cals.7 The free energy of formation from solid phosphorus and hydrogen at 25° C. is -3-3 Cals.8... 

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