Temperature of particles heated in a fluidized bed of inert material

Baskakov, A. P.; Filippovskii, N. F.; Munts, V. A.; Ашихмин, А. А.

doi:10.1007/bf00873312

Cited by 15 publications

(15 citation statements)

References 2 publications

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“…Table 3. The curves for NO x represent the results of calculations using expression (14), and the points are for experimental data. Modes: (1) 3, (2) 4, and (3) 5.…”

Section: Discussionmentioning

confidence: 99%

“…Since we are dealing with the kinetic characteristics of the nitrogen oxidation pro cess (and that of carbon k С ), we must take into account the superheating temperature T s of burning fuel particles (which was calculated from the correla tions presented in [14]) if we wish to calculate these characteristics accurately.…”

Section: Generation Of Nitrogen Oxides In Burning Coke Residuementioning

confidence: 99%

“…The first summand in expression (14) characterizes the decrease of the concentration of nitrogen oxides generated in the fluidized bed resulting from their reduction in the freeboard. The second summand describes simultaneous generation and reduction of nitrogen oxides in the flow.…”

Section: Generation Of Nitrogen Oxides During Combustion With a Shortagementioning

confidence: 99%

“…Calculations by formula (14) were carried out for the experimental conditions of firing Kuznetsk coal in a circulating fluidized bed (see Table 3 and Fig. 6) for moderate (mode 1) and intense (mode 2) circulation of coke particles and also for combustion of Estonian shale in CFB (Fig.…”

Section: Generation Of Nitrogen Oxides During Combustion With a Shortagementioning

confidence: 99%

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Generation and reduction of nitrogen oxides in firing different kinds of fuel in a circulating fluidized bed

Munts

Baskakov

et al. 2013

Therm. Eng.

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791The process through which nitrogen oxides are generated in a fluidized bed in the course of burning the particles of solid kinds of fuel was studied on an experimental setup made in the form of an electric fur nace fitted with a cylindrical heating chamber with an inner diameter of 50 mm and an air distribution hood welded into the bottom. During the experiments, we checked the temperature of fluidized bed composed of 460 μm fractions of fused alumina (or ash particles 2.5 mm in size) and air flowrate. In addition, the com position of combustion products was continuously measured using different types of gas analyzers (GIAM 5 for CO 2 , Bekman 951 A for NO x , GIAM 5M for CO, and DET V for О 2 ) and a computerized data acquisition and processing system. Brown coal from the Moscow region, Berezovo coal, Donetsk anthracite, Kuznetsk lean coal, undersized coke of Kuznetsk coal, Estonian shale, and Volga shale were used as fuel [1].For carrying out the experiments, we sieved fuel fractions with particles having medium sizes of 0.8, 1.5, 2.5, 4, 6, and 8.5 mm; small weight charges (0.5-2 g) were fired in the fluidized bed at different temper atures.Experiments involving preliminary blowing of flu idized bed with air at a temperature of 900°С showed that so called thermal nitrogen oxides (i.e., those gen erated from the molecular nitrogen contained in air according to Zeldovich' mechanism [2]) are not gen erated under the conditions of the experiment. In view of this, all generated nitrogen oxides were subse quently regarded as fuel ones, originated from the nitrogen contained in fuel.The data shown in Fig. 1 illustrate how nitrogen oxides and carbon dioxide are generated in firing small weight charges (0.5 g) composed of particles of coal from the Moscow region and anthracite. For all coals with a high content of volatiles, an interconnec tion between the changes of CO 2 and NO x concentra tions is observed: during the combustion of volatiles, a synchronous and very rapid growth of С NO and concentrations takes place, and during the combus tion of coke residue these concentrations decrease gradually to zero. If fuel with an insignificant content of volatiles is fired, the maximum of CO 2 and NO x concentrations is not so prominent: nitrogen and car bon oxides are generated more uniformly. For quanti tatively estimating the generation of CO 2 and NO x , we calculated their relative masses and that have released by a certain moment of time τ using the following expressions:where τ b o is the experimentally determined full time for which the fuel charge burns out.At the combustion stage, nitrogen oxides are gener ated more intensely than СО 2 . The relative fraction of nitrogen oxides released for the time of visible combustion of volatiles is a quantitative parameter using which this intensity can be estimated. Figure 2a shows this parameter as a function of the content of volatiles in the fuel.It should be noted that the authors of the majority of proposed calculation procedures [3][4][5] Federal University, ul. ...

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“…Table 3. The curves for NO x represent the results of calculations using expression (14), and the points are for experimental data. Modes: (1) 3, (2) 4, and (3) 5.…”

Section: Discussionmentioning

confidence: 99%

Section: Generation Of Nitrogen Oxides In Burning Coke Residuementioning

confidence: 99%

Section: Generation Of Nitrogen Oxides During Combustion With a Shortagementioning

confidence: 99%

Section: Generation Of Nitrogen Oxides During Combustion With a Shortagementioning

confidence: 99%

See 2 more Smart Citations

Generation and reduction of nitrogen oxides in firing different kinds of fuel in a circulating fluidized bed

Munts

Baskakov

et al. 2013

Therm. Eng.

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“…Physical experiments usually experience difficulty in quantifying the heat transfer mechanisms at a particle level identified many years ago (for example, Yagi & Kunii, 1957). To overcome this difficulty, in recent years, heat transfer behaviour in a fluidized bed at a microscopic, particle scale has been examined experimentally (Prins et al, 1985;Baskakov et al, 1987;Agarwal, 1991;Parmar & Hayhurst, 2002;Collier et al, 2004;Scott et al, 2004). In such a study, the transient temperature of a hot sphere immersed in the bed is measured using an attached thermocouple, and then its HTC can be determined.…”

Section: Introductionmentioning

confidence: 99%

Particle Scale Simulation of Heat Transfer in Fluid Bed Reactors

Zhou¹,

Hou²,

Yu³

2011

Heat Transfer - Mathematical Modelling, Numerical Methods and Information Technology

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Particle scale study of heat transfer in packed and bubbling fluidized beds

Zhou

Zulli³

2009

AIChE Journal

284

152

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in Wiley InterScience (www.interscience.wiley.com).The approach of combined discrete particle simulation (DPS) and computational fluid dynamics (CFD), which has been increasingly applied to the modeling of particle-fluid flow, is extended to study particle-particle and particle-fluid heat transfer in packed and bubbling fluidized beds at an individual particle scale. The development of this model is described first, involving three heat transfer mechanisms: fluid-particle convection, particle-particle conduction and particle radiation. The model is then validated by comparing the predicted results with those measured in the literature in terms of bed effective thermal conductivity and individual particle heat transfer characteristics. The contribution of each of the three heat transfer mechanisms is quantified and analyzed. The results confirm that under certain conditions, individual particle heat transfer coefficient (HTC) can be constant in a fluidized bed, independent of gas superficial velocities. However, the relationship between HTC and gas superficial velocity varies with flow conditions and material properties such as thermal conductivities. The effectiveness and possible limitation of the hot sphere approach recently used in the experimental studies of heat transfer in fluidized beds are discussed. The results show that the proposed model offers an effective method to elucidate the mechanisms governing the heat transfer in packed and bubbling fluidized beds at a particle scale. The need for further development in this area is also discussed.

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Temperature of particles heated in a fluidized bed of inert material

Cited by 15 publications

References 2 publications

Generation and reduction of nitrogen oxides in firing different kinds of fuel in a circulating fluidized bed

Generation and reduction of nitrogen oxides in firing different kinds of fuel in a circulating fluidized bed

Particle Scale Simulation of Heat Transfer in Fluid Bed Reactors

Particle scale study of heat transfer in packed and bubbling fluidized beds

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