Pressure fluctuation properties in combustion of mixture of anthracite and bituminous coal in a fluidized bed

Jang, Hyun Tae; Kim, Sang Bum; Seog, Wang; Hong, Sung Chang; Doh, Dong Sup

doi:10.1007/bf02697199

Cited by 6 publications

(3 citation statements)

References 4 publications

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“…However, both these investigations were concerned with bubbling beds and furthermore, the expected correlations were not found in any of these works. Jang et al (2003) observed that the properties of pressure fluctuations, such as mean pressure and standard deviation, varied depending on the composition of the fuel, but those quantities were not connected to fluctuations in gas concentration.…”

Section: Introductionmentioning

confidence: 93%

Dynamics of furnace processes in a CFB boiler

Johansson

Johnsson

Niklasson

et al. 2007

Chemical Engineering Science

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With the aim of understanding the dynamics of combustion, this work examines simultaneous fluctuations in fluid dynamic parameters and gas composition measured in a CFB furnace operated with coal as a fuel. The fluid dynamic parameters investigated are pressure and air flow entering the furnace. Gas composition was recorded by a zirconia-cell probe and a gas suction probe connected to a mass spectrometer having a high time resolution (10 Hz). The principal fluctuations detected are around 1 Hz and below 0.3 Hz. The fluctuations below 0.3 Hz mostly originate from variations in the fuel-feed rate. These variations create periods of reducing conditions caused by a momentarily high fuel input accompanied by a pressure rise in the furnace and a reduction of the air feed, which occurs concurrent with the release of an enhanced quantity of volatiles. Modelled pressure fluctuations based on the relation between volatile release and pressure in the furnace give similar pressure fluctuations as the measured pressure fluctuations, with respect to amplitude and characteristic time scale of the fluctuations. There is also a correlation between reducing conditions and the concentration of hydrocarbons. ᭧

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Section: Introductionmentioning

confidence: 93%

Dynamics of furnace processes in a CFB boiler

Johansson

Johnsson

Niklasson

et al. 2007

Chemical Engineering Science

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“…The hydrodynamics of BMS in a dual interconnected CFB are yet to be investigated extensively. Specifically, the effects of parameters including particle size and density, mixture composition, total solids inventory (TSI) on the pressure profile, solids holdup and solid circulation rate have not been adequately examined [2,[25][26][27][28][29][30]. In particular, studies concerning the role of the riser in determining the solid circulation rate, solids holdup and the stability of these CFBs, are very limited.In addition, to investigate the hydrodynamics of CFB, time-series analysis of pressure fluctuation (gauge or differential pressure) or other signals such as solids holdup can also be used to describe the flow regimes [25,26,29,30].…”

mentioning

confidence: 99%

“…Lue and Wu (2000) used the sum of the SD of pressure fluctuation of each species to determine the SD of the binary mixture by multiplying the fraction of each species in the mixture to its corresponding individual SD under the same operating conditions [31]. Pressure fluctuation analysis has also been used to determine the combustion region in a fluidized bed reactor by studying the SD of the pressure fluctuation, and it was found that the combustion region was related to the regions that have high SD values [27]. In addition, the dominant power spectral density (PSD) is also helpful information for investigating the hydrodynamics in a fluidized bed with the method of fast Fourier transform (FFT).…”

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confidence: 99%

Systematic Study of Pressure Fluctuation in the Riser of a Dual Inter-Connected Circulating Fluidized Bed: Using Single and Binary Particle Species

Alghamdi

Peng

Luo³

et al. 2019

Processes

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This study systematically investigates the pressure fluctuation in the riser of a dual interconnected circulating fluidized bed (CFB) representing a 10 kW th cold-flow model (CFM) of a chemical-looping combustion (CLC) system. Specifically, a single-species system (SSS) and a binary-mixtures system (BMS) of particles with different sizes and densities were utilized. The pressure fluctuation was analyzed using the fast Fourier transform (FFT) method. The effect of introducing a second particle, changing the inventory, composition (i.e., 5, 10 to 20 wt.%), particle size ratio, and fluidization velocity were investigated. For typical SSS experiments, the results were similar to those scarcely reported in the literature, where the pressure fluctuation intensity was influenced by varying the initial operating conditions. The pressure fluctuations of BMS were investigated in detail and compared with those obtained from SSS experiments. BMS exhibited different behaviour; it had intense pressure fluctuation in the air reactor and in the riser when compared to SSS experiments. The standard deviation (SD) of the pressure fluctuation was found to be influenced by the fluidization regime and initial operating conditions, while the power spectrum density (PSD) values were more sensitive to the presence of the particles with the higher terminal velocity in the binary mixture.Processes 2019, 7, 890 2 of 25 beds are complex, primarily determined by the combined effects of solids' behaviour and bubbles' characteristics in terms of development, movement, and burst. The application of chemical-looping combustion (CLC) lies between these two points, i.e., it is both part of the chemical engineering application and in energy conversion and steam production.It has been well documented that utilizing a mixture of metal oxides significantly improves the oxygen storage capacity of oxygen carrier particles in CLC systems that consist of dual interconnected circulating fluidized bed (CFB) [3,4]. This mixture of oxygen carrier was used as a single particles carrier containing both ingredients. However, other systems utilize a binary-mixture system (BMS) as two separate species that differ in sizes and/or densities in bubbling fluidized beds [5][6][7][8][9][10][11][12][13][14][15][16], and in a single-column fluidized bed [17][18][19][20][21]. Utilizing a BMS that differs in size and/or density will raise a number of operational uncertainties associated with the mixing/segregation of particles and the hydrodynamics of these complex systems. Mixing and segregation of binary solids that differ in both size and density have been investigated previously, where an operating map was developed to avoid any type of segregation (i.e., local or components segregation) in CLC systems [22][23][24]. The hydrodynamics of BMS in a dual interconnected CFB are yet to be investigated extensively. Specifically, the effects of parameters including particle size and density, mixture composition, total solids inventory (TSI) on the pressure profile, solids holdup...

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Influence of hydrodynamic parameters on particle attrition during fluidization at high temperature

Lin

Wey

2005

Korean J. Chem. Eng.

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In a fluidized bed, attrition both increases the number of particles and reduces particle size, which may affect reactor performance; fluidizing properties, operating stability and operating costs. Most fluidized applications are conducted at high temperature, but in the past most attrition correlations were performed at room temperature, so the attrition rate at high temperature could not be predicted. In contrast, this study investigates the attrition rate of fluidized materials at high temperature. Silica sand was used as the bed material; the operating parameters included temperature, particle size, static bed height and gas velocity to assess the attrition rate. Then an appropriate correlation was developed by regression analysis to predict attrition rate at high temperature. Experimental results indicated that the attrition rate increases with increasing temperature. In addition, the particle attrition increased as average particle size decreased because the probability of collision increases with surface area. The attrition rate increased with increasing gas velocity because of increased kinetic stress of particle movement. The actual density and viscosity of air at specific fluidization temperature were modified and an Ar number was introduced to fit our experimental data. The experimental correction agrees with the experimental results, which can predict particle attrition rate at high temperatures

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Pressure fluctuation properties in combustion of mixture of anthracite and bituminous coal in a fluidized bed

Cited by 6 publications

References 4 publications

Dynamics of furnace processes in a CFB boiler

Dynamics of furnace processes in a CFB boiler

Systematic Study of Pressure Fluctuation in the Riser of a Dual Inter-Connected Circulating Fluidized Bed: Using Single and Binary Particle Species

Influence of hydrodynamic parameters on particle attrition during fluidization at high temperature

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