Pulverised coal combustion

L. D. Smoot and D. T. Pratt, eds.. Pulverised Coal Combustion and Gassification, Plenum Press, New York, 1979. 

However, the question whether the combustion of oxidised or weathered pulverised coal would maintain a self-sustaining flame in a full-size industrial boiler at maximum load cannot be addressed within the present study. The inhibition of volatile matter release, due to the promotion of char condensation reactions during coal pyrolysis, suggests that this may not be the case, a point pertaining especially to the more severely oxidised coals (i.e. 373 K for 112 days). Clearly there is need for ture work within this area of pulverised coal combustion. 

Martinez-Tarazona, M. R. Spears, D. A. 1996. The fate of trace elements and bulk minerals in pulverised coal combustion in a power station. Fuel Processing Technology, 47, 79-92. 

The virtual test approach of pulverised coal combustion was based on the works of Lockwood and colleagues... 

Addition of limestone has been used to reduce slag viscosity in wet bottom coal fired plant and pulverised coal combustion, to facilitate slag and deposit removal. 

P. Flament, M. Morgan, Fundamental and Technical Aspects of SO2 Capture by Ca-based Sorbents in Pulverised Coal Combustion , International Flame Research Foundation, Doc. No. F 138/a/8,1987. 

Griest, W. H. L. A. Harris, 1985. Microscopic identification of carbonaceous particles in stack ash from pulverised-coal combustion. Fuel. 64 821-826. 

Despite the problems discussed above, LIPS has been successfully applied in a number of process analysis applications. In some cases, the LIPS system has been used off-line as in the application described by Ottesen in which air cooled metallic substrates were used to collect fly ash deposits from a pulverised coal combustion for subsequent analysis off-line [70]. Calibration standards were prepared by spraying aqueous solutions onto heated substrates using an air brush and the method was found to work well provided that the deposits were sufficiently thin to permit complete ablation. Other workers have proposed on-line LIPS systems for process control. An example is the apparatus proposed by Sabsabi [71] for in situ analysis of pre-selected components of homogeneous solid compositions. In particular, the author proposed that the system could be used for measurement of the concentration of active ingredients (e.g. drugs) in pharmaceutical products such as tablets, by monitoring an element present in the active component (e.g. 

Wall, T. F. (1992). Mineral matter transformations and ash deposition in pulverised coal combustion, In Twenty-Fourth Symposium (International) on Combustion, Combustion Institute, Pittsburgh, PA. Willeke, K., and Baron, P. A. (eds.). (1993). Aerosol Measurement ... 

Wall, T Liu, G., Wu, H Roberts, D Benfell, K Gupta, S., Lucas, J and Harris, D. (2002) The effects of pressure on coal reactions during pulverised coal combustion and gasification. Progress in Energy and Combustion Science, 28 (5), 405-433. 

Combustion of coal may take place in conventional fixed beds using lump coal and in which temperatures up to 1 300°C may be reached by entrained flow in which pulverised coal is injected into the combustion zone with the air, reaching temperatures up to 1 500°C or in the more recently developed systems of fluidised-bed combustion, again using pulverised coal but with... 

The overall objective of this study is to investigate the effect of oxidation at 373 K, using static air, and weathering, under atmospheric conditions, upon the pyrolysis and combustion of pulverised coal feedstock using laboratory-based equipment. More specifically ... 

L.S. Pedersen, P. Glarborg, K. Dam-Johansen, P.W. Hepburn, and G. Hesselmann. A Chemical Engineering Model for Predicting NO Emissions from Pulverised Coal Flames. Combust. Sci. Techn., 132 251-314,1998. 

M. A. Field and co-workers, Combustion of Pulverised Coal, British Coal Utilisation Research Association, Leatherhead, Surrey, U.K, 1967. 

D. B. Antony, J. B. Howard, H. C. Hottel and H. P. Meissner, Rapid devolatilization of pulverised coal, I5th Sym. (International) on Combustion, Tokyo, Japan, 25-31 August 1974. 

The simulation program AIOLOS is developed for the numerical calculation of three-dimensional, stationary, turbulent and reacting flows in pulverised coal-fired utility boilers. AIOLOS contains submodels treating fluid flow, turbulence, combustion and heat transfer. In these submodels equations for calculating the conservation of mass, momentum and energy are solved, presupposing high Reynolds-numbers and steady-state flow conditions. It is assumed that the flow field is weakly compressible which means that the density depends only on temperature and fluid composition but not on pressure. 

At present EPON is studying the feeding of wood particles directly into the pulverised coal transport lines after the pulverisers, since the injection with the separate wood burners was subject to some problems, such as the occurrence of large pieces of unbumed wood in the bottom ash. The first experiences with this method of feeding observed no negative implications. Recently, the power plant applied for a permit to expand the wood co-combustion activities from 3 to 10 per cent of the coal input, to be done with the direct feeding of pulverised wood into the pulverised coal transport lines. 

UNA is investigating the installation of pyrolysis units from Pyrovac, with a total capacity of 120 kton/a at the Hemweg power plant. With this so-called Pyrocycling process the main objectives are to produce char and oil, which can be co-combusted directly with the pulverised coal or, if desired, be stored and co-combusted later at Hemweg or at another power plant. 

Beekes M.L. et al (1998). Co-combustion of biomass in pulverised coal-fired boilers in the Netherlands... 

A further inq)rovement for the conc.-COa-methanol path is the COa-recovery upstream the combustion after CO shift in an IGCC-plant with the selexol absorption process. This technology has a better COa balance than the pulverised coal fired plant with MEA-process technology due to the less decrease in IGCC efSciency from 42% (reference efSciency) to 36% only (after COa capture) [4] but it should be mentioned, that this technology is not state-of-the-art today. The efficiency of the air-COa-methanol vector was calculated to be 38.1%. With more advanced technologies (e.g. high temperature processes), the efSciency can be improved to more than 44% [6]. 

Williams, A. Pourkashanian, M. Jones, J.M. Combustion of pulverised coal and biomass. Prog. Energy Combust. Sci. 2001, 27, 587-610. 

The certification of a range of trace elements has been certified in a reference material of fly ash obtained from the combustion of pulverised coal (CRM 038) in 1982 [15,16]. Following requests made by the coal industry and control laboratories, this material has been additionally certified for its content of F and Cl in 1994, following two intercomparisons which involved 14 laboratories (dealing with fluorine solutions with increasing concentrations) [17]. 

Additives may be solid or solutions, or suspensions in a suitable solvent, or liquid. Where solids are employed their particle size is usually of the order of 20 -30 fjtn with direct injection into the combustion space in the vicinity of the burner where pulverised coal or liquid fiiels are employed. For solid fuel combustion on a grate, the additive may be mixed with the fuel prior to combustion or injected in some way to the flame region. Mbdng with the fuel may present difficulties of producing a uniform distribution, particularly for solid fuels. The additive is usually separately applied to avoid these problems. 

In pulverised coal firing the coal is reduced in size to provide about 90% below 75 /jm [Highley and Kaye 1983] mixed with air in suitable burners firing into the combustion space (as generally illustrated in Fig. 16.14). Secondary air may be admitted to ensure complete combustion is achieved. 

A modification of the pulverised coal plant has a combustion chamber in the form of a cyclone. Molten slag is collected on the walls of the chamber and flows downwards and out of the bottom through a specially designed port. The design is generally known as a "slagging combustor" or "cyclone combustor". 

Although the rate of rise of temperature in the test is carefully controlled, the rate of heating in industrial equipment will be quite different, and will vary between different combustion techniques, e.g. chain grate, pulverised coal and fluidised bed combustion. Furthermore in an industrial process the ash is... 

Preheated air can improve combustion of pulverised coal in thermal power plants. It can minimise carryover of unburnt droplets of liquid sulphur in a sulphuric acid plant. 

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