Calorific value biomass

Operationally the testing has proven successful. Cofiring has occurred at loads from 106 MW (net) to 188 MWe (net) without conq)romising boiler capacity. Cyclone feeder speeds have increased as a consequence of cofiring a modest calorific value biomass fuel with a typical heat content of 11.14 - 11.60 MJAcg (4800 - 5000 Btu/lb) with a high calorific value coal with a typical heat content of about 29.0 MJ/kg (12,500 Btufib). 

Table 2.2 Elemental analyses (wt.%) and calorific values (FIFIV, MJ/kg) of biomass samples...

Coal is a rich source of carbon and has been a valuable source of fuel for centuries. It is classified by both coal type and coal rank. Coal type is determined by the nature of the original biomass that led to the formation of the coal. Coal rank signifies the degree of maturation or chemical change in coal and usually determines coal quality. The calorific value, moisture content, elemental analysis, volatile matter, ash, and fixed carbon content are important qualities of coal. 

Although Jerusalem artichoke tops need extensive drying, they can be a useful source of biomass for direct combustion. Trials in Lithuania have confirmed Jerusalem artichoke s suitability as an energy crop. The bulk density of tops harvested in autumn was 78 kgm3, compared to 65 kgm3 in the spring, while the average net calorific value of dry biomass harvested in autumn was 18.0... 

Possum, M., Beyer, R.V., (1998) Co-Combustion of natural gas and low calorific value gas from biomass. SINTEF Energy Research, Report prepared for lEA Biomass Gasification Activity, Trondheim. 

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. 

Thermal conversion of biomass/waste streams in oses demands on the fuel quality. The basic physical properties of the biomass and waste streams, such as moisture content, ash content and melting temperature, particle size (distribution), density and calorific value are irrqioitant properties, which determine the design specifications of a new installation to a large extent, The fact that biomass and waste Streams are usually til defined, leads to a significant spread in physical and chemical data. 

Andrics J. Hoppestcyn P. D. J. (1997) Pressurized combustion of biomass-derived low calorific value, fuel gas. In Biomass, Gasification and Pyrolysis, (Ed. by M. Kaltschmitt A. V. Bridgwater), pp. 1282-291. 

Berger, R., and Wiinning, J. G. "Burners for the Process Integrated Combustion and Utilisation of Biomass or Waste Derived Low Calorific Value Gases." Eighth European Conference on Industrial Furnaces and Boilers, Vilamoura, Portugal, 2008. 

Successful implementation of an opportunity fuel prc ram must accomplish technical, environmental, an or economic in rovements. These can be increases in boiler capacity or efficiency, either through the use of a high calorific value fuel (petroleum coke, TDF) or by the design of the system used to introduce the fuel into the boiler (e.g., separate injection of biomass into a PC boiler can overcome pulverizer limitations on capacity). There can be reductions in emissions of SO2, NO CO and hydrocarbons, and mercury and other trace metals associated with the use of opportunity fuels. TDF fired with medium sulfur bituminous coal can have a significant benefit with respect to SO2 emissions. In roperly used, however, opportunity fuels can increase certain emissions including opacity. 

Most authors also recognize that woody biomass fuels, while low in sulfur and possibly low in nitrogen and ash, are also modest in calorific value. Further, they can be high in moisture content and they can contain extraneous materials from harvesting or processing. With few exceptions, these fuels are highly reactive with significant volatility. 

The use of tire-derived fuel as a cofiring feedstock in power generation has many advantages. Hrst, because of the high calorific value of TDF, particularly the wire-free TDF, the cost of TDF in GJ (ot /10 Btu) is lower than that of any fossil fuel - with the possible exception of Powder River Basin coal delivered locally or to a mine-mouth plant - and is competitive with even the lowest cost biomass fuels. This, combined with the lower ash content of TDF (without steel) makes it a viable blending fuel. In addition, the sulfur content of TDF is less than most eastern bituminous coals and conq>arable to medium-sulfur coals throughout the world. 

The result of a comprehensive literature review by Behrendt consistently confirmed that the hydrothermal treatment of biomass coals by dehydration and decarboxylation yields a product with calorific value of about 30 MJ/kg whose elemental composition is similar to that of lignite [10]. The carbon content and the properties of such cokes strongly depend on the starting materials and the process paramters applied, namely temperature and residence times of 4—14h. The coke yields can reach values of up to 70% (g/g) and even higher values if catalysts such as citric acid are used. Those products have an increased calorific value of 15-20%, relative to the dry weight. About 80-85% of the carbon remains in the coke, about 10-15% remains in the aqueous phase in the form of organic acids and other... 

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