High calorific value

The great advantage of LPGs is that they are stored as a liquid. However, they are usually used as a gas. One volume of liquid propane when released at STP gives 274 volumes (233 for butane) of high calorific value fuel gas. 

For SNG manufacture, it is necessary to reduce the residual hydrogen to a minimum in order to achieve a high calorific value. This is best realized if the synthesis gas, instead of having a stoichiometric composition, contains a surplus of C02 which can be utilized to reduce the H2 content by the C02 methanation reaction to less than 1% according to equilibrium conditions. The surplus C02 must be removed at the end of the process sequence. It is, of course, also possible to operate a methanation plant with synthesis gas of stoichiometric composition then there is no need for a final C02 removal system. The residual H2 content will be higher, and therefore the heating value will be lower (cf. the two long term runs in Table II). 

Other attempts to improve nitrodiglycol powders were based on the introduction of substances such as penthrite (German Nipolit Pulver) and cyclonite. In both cases a powder with a high calorific value was obtained. The manufacture of these powders never went beyond the pilot plant scale ... 

A hard type of coal with a high calorific value. 

The rotary kiln design allows for accepting a mix of high-chlorinated wastes (solvents, chlorinated tars, plastics). Such kilns are usually designed in relation to a specific optimal calorific value in the input. The input mix should be set in such a way that this optimal composition is approached (e.g., PVC waste and other waste streams with a lower calorific value). It is likely that a 100% input of PVC would lead to all kind of problems of temperature control due to its relatively high calorific value. Chlorine contents of over 50% can easily be accepted. A final demand is that the particle size should be 10 x 10 x 10 cm at maximum. This implies that sometimes waste has to be shredded before it can be put into the kiln. Other acceptance criteria have not been published in literature. 

Material recycling is the objective for every material, but at some point reuse or collection, separation and further recycling will no longer yield a useful product. The so-called plastic waste still contains a high calorific value which can be recovered to produce heat or electricity. Even better it may be possible to recover the chemical feedstock originally manufactured from oil. These two possibilities are reviewed. 

Mastral, A.M., Callen, M.S., Murillo, R., and Garcia, T., Combustion of high calorific value waste material Organic atmospheric pollution, Environment. Sci. TechnoL, 33, 4155, 1999. 

The pure carbon that occurs in coal is fixed carbon, and the higher the content, the greater the calorific value of the coal. Total carbon implies the fixed carbon plus the carbon present in the volatile matters (in CO, C02, CH4, and hydrocarbons). The total carbon content is thus always higher than the fixed carbon in any coal. A high total carbon-bearing coal will be characterized by a high calorific value. 

Of the 25% share of coal in world primary energy supply, hard coal makes up around 90% (BGR, 2007). Owing to its high calorific value, the main use of hard coal is for electricity generation (60% of world hard coal production), 16% is used for steel making, and the rest in other industries and households. While in the EU25 around one third of the electricity is produced by (hard) coal, this share amounts to 50% in the United States, 70% in India, 80% in China, 85% in Australia, 90% in South Africa and 93% in Poland. 

After firing, restoring the bomb pressure to atmospheric pressure too rapidly may result in the loss of oxides of sulfur and nitrogen. A correction must be made to the gross calorific value for the amounts of these acid-forming oxides produced in the bomb. Their loss results in a high calorific value. The pressure of the bomb must be restored very slowly to prevent this. 

Analytical data on the residues from five extractions are given in Table IV. The high calorific value of the extraction residues, combined with their significant volatile matter content and relatively low ash content, indicates that they should be attractive materials for combustion. 

Another approach receiving increased interest is direct reduction of iron ore. In this process, coal is added directly to the smelting vessel and is the source of the reducing gases and thermal energy. Thus, easily crushed and handled, inexpensive noncoking coals of high calorific value can be used. Particle size requirements are variable, but less than 1 mm is most often used and, in some cases, there is an effort to restrict moisture content to below 6 percent. 

Pyrolysis can be performed for many different reactors. The prodnct distribntion varies markedly between the different reactor types and the reaction conditions, snch as temper-atnre, bed materials or catalyst. The aim of the pyrolysis is the redaction of wastes for landfilling and the prodnction of fnels. Especially fuel oil with a high calorific value is an interesting product. Char can be used as a fuel, but is also seen as a precursor for other carboneous materials such as activated carbon. The best way to obtain these products is decarboxylation of the polymer. In this way carbon oxide-rich gas is produced. 

The High Calorific Value of the oil shales was determined by a "bomb" calorimeter on more than 90 composite samples from different deposits and on one-meter samples along borehole sections. The average value is lOOOKcal/Kg and the highest value measured was 1790Kcal/Kg. The correlation between organic matter content and the calorific value is more than significant (R=0.96). The equation for the Ef e deposit is ... 

Figure 5. Correlation between organic matter content and high calorific value (Ef e and...

Veba 01 (originally GMU), Riitgerswerk A.G. and Eisen und Metall A.G. collaborate in the development of a heated rotating drum furnace for the recovery of metals and oil from special wastes, such as tyres, cable wastes and acid tars with a high calorific value. The oil is separated into benzene, toluene, naphta-lene and heavier fractions by distillation [22,23,24,25] ... 

These consist primarily of material high in carbon content, which is practically odourless. Because of their high calorific values of more than 30.000 kJ/kg it is possible to use them as fuel or as raw material for gas generators. If properly treated, they can also be used as filler materials by the rubber industry or as fillers or dyes by the chemical industry (see table 3). In our case the pyrolysis of 1 ton of used tyres produced 365 kg of solid residues, most of which, namely 49.7 % had a grain size between 0.1 and 0. 5 mm. 

High calorific value combustible gas can be produced, since produced gas is not diluted by flue gas in the reactor. 

Gas. Gas has a high calorific value of more than 1+2,000 KJ/ NM. It is used as fuel for heating the pyrolysis kiln along with the recovered light oil. 

At the end what matters is to have a natural gas with a high calorific value. In Table 3, heating values for typical components in clean natural gas are provided ... 

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