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The solid waste generated from the apple juice industry (apple bagasse (AB)) was characterized as a fuel, and the potential for its utilization as an alternative energy source was assessed through its combustion in a pilot scale cyclone combustor. A comparative evaluation of the AB and sawdust (SD) properties, as well as of the emissions during the combustion tests, was performed. The high energy content of AB (lower heating value (LHV) equal to 21.09 MJ kg−1), dry and ash-free (daf) basis, which is 26.9% higher than the LHV of SD (16.62 MJ kg−1, daf), and combined with the high volatile matter content (85.36 wt %, daf) improve the ignition and burning of the solids. The emissions of CO, SO2, and NOx and the total organic carbon (TOC) were compared with guideline limits established by Brazilian and international legislation. AB generated much lower CO than sawdust in spite of almost half of excess air levels (13% compared with 26%) and met even the stringent limit of the German regulation for waste incineration. The unburned carbon percentages found in the ash resulted from SD and AB combustion tests were 0.24% and 0.96% in weight, respectively. The absence of sulfur in AB composition represents an advantage with nondetectable SO2. The average level of NOx emission with SD combustion was 242 mg N m−3 and met all the regulation limits. The average NOx emission with AB combustion though was 642 mg N m−3 and met the U.S. EPA regulation but was marginally higher than the Brazilian norm by 15%. TOC concentrations remained below the limits considered even though the TOC level was higher in the AB combustion test. Polycyclic aromatic hydrocarbons (PAH) were not detected or were under the quantification limit of the equipment used in their analysis. Comparing the properties, the burning profiles of SD and AB, and the emissions from their combustion tests, it can be stated that the waste originating from the apple juice industry is suitable for direct combustion, constituting a renewable energy source for this industrial sector.

Flotation sludge from the meat processing industry can be applied as biofuel in already existing plant-scale boilers. This biosolid is rich in oil and grease and has higher energetic content on a dry ash-free basis (22.74 and 27.71 MJ kg −1 ) than the wood-based fuel (16.62 and 16.16 MJ kg −1 ). Co-combustion trials were performed at a pilot-scale cyclonic combustor (100 kg h −1 ) and at an industrial flamotubular rotatory grate-fired system (6000 kg h −1 ), co-firing pre-dried and centrifuged flotation sludges (respectively) and wood at a mass ratio of 1:3. At a moisture content of 60.13 wt%, the lower heating value of the centrifuged sludge was 10.24% lower compared to wood, thus reducing it to at least 40 wt% would be advisable to obtain energy gains in the industrial plant when operating the co-combustion. The emissions were evaluated and compared to emission standards, including the characterization of polycyclic aromatic hydrocarbons and polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (given as Toxicity Equivalent Factors at O 2ref = 7%), which have not yet been reported. The 16 target polycyclic aromatic hydrocarbons were identified at pilot and plant scales (0.582 ± 0.143 μg Nm −3 and 0.602 ± 0.506 μg Nm −3 , respectively) being lower than the Danish reference standard (5.0 μg Nm −3 ). The polychlorinated dibenzop-dioxins and polychlorinated dibenzofurans concentrations were 0.0004 ± 0.0001 ng Nm −3 at pilot scale and 0.3617 ± 0.1310 ng Nm −3 at plant scale, both below the Brazilian and American standards but differed greatly between the scales, requiring further investigation since their formation can occur due to combustion and postcombustion conditions.

The effect of thermal efficiency on the individual items of nuclear power cost is considered. NOTICEThis document contains information of a preliminary nature and was prepared primarily for internal use at the Oak Ridge National Laboratory. It is subject to revision or correction and therefore does not represent a final report.

The thermal conversion of biomass fuels using different combustion technologies has increased worldwidely in the latest years due to the energetic exploitation potential of wastes as well as to the strong increase of environmental consciousness in the industrial sector. In this work the bagasse obtained from the apple juice industry (AB) was characterized and the gaseous emissions resulting from its combustion in a pilot scale cyclone combustor were measured and compared to limits imposed by Brazilian and international current legislations. Wood and wood-based materials are extensively used as fuel for thermal energy generation particularly in the Brazilian food industry, which demands large amounts of steam. Considering that, sawdust (SD) was also characterized, burned in the same conditions and the gaseous emissions analyzed for comparison purposes. Sampling for the volatile organic compounds benzene, toluene, ethyl-benzene and xylene (BTEX, expressed as total organic carbon, TOC) and polycyclic aromatic hydrocarbons (PAH) were performed and the samples analyzed by gaseous chromatography-mass spectrometry (GC-MS). Chemical properties showed that the volatile matter value of AB is high (85.36 wt%, daf) what indicates that the solid burn rapidly. The absence of sulfur in its composition represents an advantage in relation to fossil fuels because its combustion does not release sulfur derived compounds. The lower heating value is 21.09 MJ.kg−1 (daf), 26.9% higher than the heating value of SD (16.62 MJ.kg−1). The effect of the N fuel content found in AB composition was clearly noticed through the high NOx concentration in the flue gas resulted from its burning. Comparing the properties and the burning profiles of SD and AB, it can be stated that this industrial waste obtained from the apple juice industry is suitable for direct combustion, constituting a renewable energy source for this industrial sector, however, measures as air staging and staged addition of fuel, or flue gas cleaning technologies would be required for reducing the NOx emission. Concerning the presence of toxic compounds as PAH, they were not detected once the operation conditions applied resulted in controlled gaseous emissions and temperature profile. Also, TOC concentrations remained below the regulations limits considered.