It is the objective of this thesis to take into account thermal balance of circulating fluidised bed combustors (CFBC), aiming at efficiency assessment, as regards standards, CSN 07 0302, and DIN 1942. It points to differences between calculations along these two different standards, concerning the solution of problems like different comparative temperatures, to which the calculation of physical losses is related to, varying calculation of mean thermal capacity, or problem of electrical motors input. This article is based on the project GA 617 50 11 solving - "Combine combustion of coal and biomass in fluid boilers"., Zdeněk Kadlec, Bohumir Čech and Jan Matoušek., and Obsahuje bibliografii
Most of natural materials contain traces of chlorine and it enters also to the combustion process. Chlorine products of combustions are usually inorganic hydrogen chloride vapors and chloride salts, nevertheless smaller amount of organic chlorine compounds are formed. Simpler of these organic compounds can act as greenhouse and ozone depleting gases; more complex compounds are directly dangerous for their mutagenity or extreme toxity like so called dioxines. Non-fossil natural materials and fuels derived of them can contain more chlorine than common coal. From the published research studies is evident that the formation of organochlorine compounds is limited to the temperature range 300-800 °C. At the higher temperatures, these compounds are destroyed. In the stage of flue gas cooling some chlorine may be by a "de novo" synthesis introduced to the organic form. Well-controlled combustion of alternative fuels need not contribute to the increase of amount of emissions of dangerous chlorine compounds. In our research were moreover studied the fuels with lower chlorine content. The experimental tests of the emissions from large-scale industrial fluid bed boiler indicated that substitution of large percentage of coal by alternative fuels had no significant effect., Kamil Wichterle, Jan Cieslar, Antonín Klečka, Zdeněk Klika and Václav Roubíček., and Obsahuje bibliografii
We describe behavior of the air-coal mixture using the Navier-Stokes equations for gas and particle phases, accompanied by a turbulence model. The undergoing chemical reactions are described by the Arrhenian kinetics (reaction rate proportional to exp(−ERT), where T is temperature). We also consider the heat transfer via conduction and radiation. Moreover we use improved turbulence-chemistry interactions for reaction terms. The system of PDEs is discretized using the finite volume method (FVM) and an advection upstream splitting method as the Riemann solver. The resulting ODEs are solved using the 4th-order Runge-Kutta method. Sample simulation results for typical power production levels are presented.
The replacement of fossil fuels with renewable sources for heating and drying of cereals nowadays generates a great deal of debate. The greatest representation in renewable fuel sources has biomass, particularly woodchips and straw. This paper presents the results of check measurement on a heat source for heating and warn water preparation. Selected dependences of production of carbon monoxide, carbon dioxide, nitrogen oxides, content of oxygen, of total organic carbon are presented. This knowledge implies requirements to abandon the idea of ecological harmlessness of heat production from biomass. As far as biomass substitutes fossil fuels, the environmental impact is more favourable. and Obsahuje seznam literatury