Experimental investigation of wood combustion and combustion profiles in a cylindrical combustion chamber

This study presents the results of an experimental investigation of wood combustion. Variables chosen for investigation were fuel feed rate, fuel moisture content, fuel particle size, excess air, fraction and temperature of under-fire air. Data recorded during the experiments included the composition and temperature of the combustion products in the combustion chamber, particulate emissions and combustible fraction of the particulate. Most mathematical models describing the combustion of wood particles require numerical solutions. For this investigation, an alternative model was used to generate closed form solutions for the determination of the burning times for wood particles in the combustion chamber. The model results were in good agreement with the experimental findings. The temperature profiles of combustion products within the combustion chamber were closely estimated, using an analytical model developed for this investigation. The composition profiles within the combustion chamber were estimated with the use of a chemical equilibrium model. These models were in good agreement with the experimental results for the estimation of the oxygen and carbon dioxide contents of the combustion products. The chemical equilibrium model proved to be inadequate for the determination of the NO[subscript x] and CO contents of the combustion products. Based upon the experimental data, a linear regression model was developed to investigate the variables affecting the combustion process. A computer model was used to calculate the temperature and composition of the combustion products under adiabatic conditions. Over the range of the variables considered, it was concluded that combustion efficiency and particulate emissions were most influenced by the factors that increased the volume and velocity of combustion products in the chamber. Moreover, it was also concluded that the part-load operation of the combustion unit resulted in higher particulate emissions and lower combustion efficiency

Analysis of wood combustion and combustion systems for a combined cycle wood-fired power plant

This report presents the study of wood combustion and combustion systems for a combined cycle wood-fired power plant. The power plant consists of a twin air cycle and a single steam cycle. The fuel for this power plant is wood and wood waste with particle size in the range of three inch minus and a moisture content of 35 to 60 percent wet basis. The distinguishing features of this power plant are: direct combustion of wood, indirect-fired gas turbine, and combined cycle with a gas turbine cycle and a Rankine steam cycle. The three alternative designs of this power plant were considered. System 2 is designed for dry fuel combustion, with a dryer utilized. System 5 is designed for wet fuel combustion; therefore, the dryer of system 2 is not used. In system 7, which is designed for wet fuel combustion, a trimburner is used to increase the inlet temperature of the gas turbine from 1450 F to 1612 F. The wood fuels have a wide range of particle size and moisture content which affect the combustion of the fuel. In this report the combustion of wood and the effects of variables such as moisture content, particle size, and excess air on combustion of wood have been analyzed, and the results of the analysis are presented. Because of the variety of wood combustion systems available, in this work several combustion systems have been reviewed with the purpose of recommending a combus tion system for the use in this power plant. An evaluation of wood combustion based on the principles of conservation of mass, the first law of thermodynamics, the second law of thermodynamics and a prescribed extent of completion is presented. A computer program based on this evaluation is provided. The results of analysis based on this model and the computer simulation of the power plant are presented. Recommendations for improved operating conditions of the combustor, selection of the combustion system, and improvements in power plant design and operation are made. Based on the analysis presented in this work, it is concluded that system 7 is the most efficient system among the three systems considered

pH-Responsive Hybrid Hydrogels as Antibacterial and Drug Delivery Systems

This study describes the design and synthesis of organic–inorganic hybrid hydrogels based on an interpenetrating polymer network (IPN) composed of polyaspartic acid crosslinked by graphene nanosheets as the primary network and poly(acrylamide-co-acrylic acid) as the secondary network. Silver, copper oxide, and zinc oxide nanoparticles were formed within the gel matrix, and the obtained hydrogel was applied to a load and controlled release of curcumin. The loading of curcumin and the release of this drug from the gels depended on the nanoparticle’s (NP’s) content of hydrogels as well as the pH of the medium. The synthesized hydrogels showed antibacterial activity against E. coli and S. aureus bacteria. The ability of the synthesized hydrogels to incapacitate bacteria and their loading capacity and controlled release of curcumin qualify them for future therapies such as wound-dressing applications