Calorific value, estimation

Comprehensive reviews of energy sources are pubflshed by the World Energy Conference, formerly the World Power Conference at six-year intervals (83). The 1986 survey includes reserves and also gives total resources. In 1986 the total proven reserves of recoverable soHd fuels were given as 6 X 10 metric tons. One metric ton is defined as 29.2 x 10 MJ (27.7 x 10 Btu) to provide for the variation of calorific value in different coals. The total estimated additional reserves recoverable and total estimated additional amount in place are 2.2 x 10 and 7.7 x 10 metric tons, respectively. These figures are about double the 1913 estimates, primarily because significantly increased reserves have been indicated for Russia. 

On a uniform calorific value basis, coal constitutes 69% of the total estimated recoverable resources of fossil fuel in the United States. Petroleum and natural gas are about 7% and oil in oil shale, which is not as of this writing used as a fuel, is about 23%. The 1989 total recoverable reserves of coal are about 500 times the 1989 aimual production (2), whereas the reserves of oil and gas are smaller, the production and consumption rate of oil and gas in the United States is three times that of coal. 

The reactor is a pipe reactor heated with fuel gas, gross calorific value 33.5 MJ/m3. Estimate the quantity of fuel gas required. 

Make a rough estimate of the cost of steam per ton, produced from a packaged boiler. 10,000 kg per hour of steam are required at 15 bar. Natural gas will be used as the fuel, calorific value 39 MJ/m3. Take the boiler efficiency as 80 per cent. No condensate will be returned to the boiler. 

In this paper, we demonstrate how mean maximum reflectance of vitrinite in oil (hereafter referred to as R ) can be used in place of conventional chemical-rank parameters (volatile matter and fixed carbon) to estimate the relative yields of carbonization products, specific properties of gas produced by carbonization, and chemical properties of coal such as calorific value and free swelling index (FS1). Further, we illustrate that measured R can be used to detect coal oxidation, to categorize coals for certain combustion uses, and to help classify coals by rank. 

This investigation shows that the average reflectance of vitrinite in coal (Ro) can be used to estimate carbonization product yields, by-product gas properties, chemical properties, oxidation effects, and combustion behavior. Moreover, R along with calorific value and volatile matter content might be employed to classify accurately and consistently coals of all ranks. 

Inherent or equilibrium moisture is used for calculating moist, mineral-matter-free calorific values for the rank classification of high-volatile bituminous coals. It is also used for estimating free or surface moisture, since total moisture is equal to the sum of the inherent moisture and the free moisture and is considered the inherent moisture of the coal as it occurs in the unexposed seam, where the relative humidity is probably near 100%. However, due to physical limitations, equilibrium moisture determinations are made at 96 to 97% relative humidity and used as inherent moisture values. 

If a coal does not have a measured calorific value, it is possible to make a close estimation of the calorific value (CV) by means of various formulas, the most popular of which are (Selvig, 1945) ... 

Let us consider that a mixed waste contains different components, each being characterized by its water content W, volatile matter VM and ash content A (the last two being on a dry basis). Assuming that each component behaves independently and using the hypothesis of additivity, it is possible to estimate the product yields after carbonization. Moreover, this model takes into account the different carbonization yields for each component (according their physical and chemical properties). From the C, H, O analysis of each component (easier than that for the rough mixture), it is possible to estimate the net calorific value of the char and the gases from the waste pyrolysis. 

In order to satisfy energy balance requirements, the combustion heat output (Qgaspraiucts) foi" ideal case should equal the net calorific value (Q J of a biomass fuel. Using this relationship, the combustion temperature (T) can be estimated by approximation as shown in Eqn 7. Predicted combustion temperatures for the biomass fuels tested and derived by this method are shown in Table 4. 

Cell concentration in the medium was estimated as diy cell weight. The harvested cells were collected by centrifugation (12,000 x g, 4 C for 15 min) and washed with distilled water. The cells dried under reduced pressure were subjected to chemical analysis. The calorific value of the cells was measured using an automatic bomb calorimeter (CA-3, Shimadzu, Japan). Elemental composition of the cells was measuredusing an automatic elemental analyzer (EA1108, Fisons Instruments Co., Italy). 

An alternate method of calculation of the calorific value, when an experimental determination is not available or cannot be made conveniently, involves an estimate of this property (ASTM D-6446). In this test method, the net heat of combustion is calculated from the density and sulfur and hydrogen content, but this calculation is justifiable only when the fuel belongs to a well-defined class for which a relationship between these quantities has been derived from accurate experimental measurements on representative samples. Thus the hydrogen content (ASTM D-1018, ASTM D-1217, ASTM D-1298, ASTM D-3701, ASTM D-4052, ASTM D-4808, ASTM D-5291, IP 160, IP 365), density (ASTM D-129, ASTM D-1250, ASTM D-1266, ASTM D-2622, ASTM D-3120, IP 61, IP 107), and sulfur content (ASTM D-2622, ASTM D-3120, ASTM D-3246, ASTM D-4294, ASTM D-5453, ASTM D-5623, IP 336, IP 373) of the sample are determined by experimental test methods, and the net heat of combustion is calculated with the values obtained by these test methods based on reported correlations. 

The volatile matter in coke affects the density of coke particles and can affect artifacts produced from further processing of the coke. The volatile matter can be used in estimating the calorific value of coke. 

Similar to the case of oil shale, DSC analyses may be carried out under conditions wherein the organic matter in coal undergoes combustion to yield its calorific value. Such estimates are... 

Combustible The net heat of combustion and the calorific value help to estimate the potential energy which can be recovered from burning used solvents. In addition, the composition of the combustion products is considered to evaluate potential corrosiveness and the effect on the environment. 

ASTM D 1405-95a. Standard test method for estimation of net heat of combustion of aviation fuels. ASTM D 5468-95. Standard test method for gross calorific value of waste materials. 

Hv(Tb) and dy both can be estimated at combustion reference conditions using DIN 51857 1997-03 Gaseous fuels and other gases - Calculation of calorific value, density, relative density and Wobbe index of pure gases and gas mixtures [11], It is normal to give a Wobbe Index without units avoid any possible confusion with the volumetric heating value of the gas [12]. 

Use of cheap and inexhaustible U and Th fuel, whose calorific value is 3 million times greater than that of coal, may open a new era in human history. With the average U and Th content in the Earth crust estimated at 4 x 10 t and 10 t, respectively, their reserves of 10 t in the strata down to 2 km are so great that even a thousandth part of them will last for... 

Duarte and Maugeri (2014) studied lipid production by Candida sp. LEB-M3 cultivated in pure and raw glycerol. The feasibility of biodiesel production by the yeast Candida sp. LEB-M3 was indicated by predicting FAME properties for pure and raw glycerol respectively, including cetane number (56—53), heat of combustion (37—39 kJ/g), oxidative stability (8.58 h), kinematic viscosity (3.82—3.79 mm /s), density (807—872 kg/m ), and iodine index (74—115.5 gE/lOOg). Leiva-Candia et al. (2015) estimated biodiesel properties produced from SCO derived from Rhodosporidium toruloides, Lipomyces starkey, and Cryptococcus curvatus cultivated on biodiesel by-product streams. More specifically, cetane number (62.39—69.74), lower calorific value (37,393.49—37,561.68 kJ/kg), cold-filter plugging point (4.29—9.58°C), flash point (158.73—170.34°C), and kinematic viscosity (4.6—34.87 mm /sat 40°C) were determined. 

Deposits of coal are dispersed across all large land-masses. Estimates of total accessible reserves indicate that the amounts are sufficient to meet projected needs during the next three to five centuries. The uncertainty in this estimate arises in forecasting the ease of extraction because many seams are thin, necessitating the removal of large amounts of rock. The economic value of coal also depends on location, calorific value and concentrations of undesirable impurities (including sulfur). 

In 1991, the total coal reserves were estimated to be about five times greater than the equivalent petroleum reserves and six times greater than the reserves of natural gas (based on calorific value). Petroleum and natural gas reserves combined have been projected to be capable of supplying energy demands for about 50 years. 

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