External bed materials for the oxy-fuel combustion of biomass in a bubbling fluidized bed

A study on the heating of inert bed solids in a bubbling fluidized bed by means of an over-bed start-up oil burner is presented in this paper. Experiments carried out in a 160 mm diameter bed shows that the bed heats up nonlinearly with time. The rate of heating and the peak temperature reached by the bed solids depend on the bed depth, the mean particle size, and the superficial velocity through the bed. It was further noted that premixing a certain amount of biomass with the inert bed solids accelerates the rate of heating, as well as increase the peak temperature attained. The internal heat generation in the biomass is found to start at temperatures as low as 200°C. Thus, premixing some biomass with inert bed materials could reduce the combustion start-up time of a fluidized bed boiler, reducing at the same time the start-up cost by saving on consumption of expensive fuel oil in the burner. Experimental data in the present laboratory-scale unit shows good agreement with those obtained earlier in an industrial fluidized bed tested with waste-coal.

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Study of bed materials agglomeration in a heated bubbling fluidized bed (BFB) using silica sand as the bed material and KOH to simulate molten ash

Powder Technology ◽

10.1016/j.powtec.2015.12.030 ◽

2016 ◽

Vol 291 ◽

pp. 178-185 ◽

Cited By ~ 8

Author(s):

Alejandro Montes ◽

Ehsan Ghiasi ◽

Honghi Tran ◽

Chunbao (Charles) Xu

Keyword(s):

Fluidized Bed ◽

Silica Sand ◽

Bubbling Fluidized Bed ◽

Bed Materials ◽

Bed Material

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Feature Selection and Uncertainty Analysis for Bubbling Fluidized Bed Oxy-Fuel Combustion Data

Processes ◽

10.3390/pr9101757 ◽

2021 ◽

Vol 9 (10) ◽

pp. 1757

Author(s):

Katerina Marzova ◽

Ivo Bukovsky

Keyword(s):

Feature Selection ◽

Fluidized Bed ◽

Sampling Period ◽

Fuel Combustion ◽

Selection Algorithm ◽

Data Set ◽

Feature Vectors ◽

Combustion Emissions ◽

Bubbling Fluidized Bed ◽

Validation Technique

This paper presents a novel feature extraction and validation technique for data-driven prediction of oxy-fuel combustion emissions in a bubbling fluidized bed experimental facility. The experimental data were analyzed and preprocessed to minimize the size of the data set while preserving patterns and variance and to find an optimal configuration of the feature vector. The Boruta Feature Selection Algorithm (BFSA) finds feature vector’s configuration and the Multiscale False Neighbours Analysis (MSFNA) is newly extended and proposed to validate the BFSA’s design for emission prediction to assure minimal uncertainty in mapping between feature vectors and corresponding outputs. The finding is that the standalone BFSA does not reflect various sampling period setups that appeared significantly influencing the false neighborhood in the design of feature vectors for possible emission prediction, and MSFNA resolves that.

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Combustion characteristics of straw stored with CaCO3 in bubbling fluidized bed using quartz and olivine as bed materials

Applied Energy ◽

10.1016/j.apenergy.2017.12.112 ◽

2018 ◽

Vol 212 ◽

pp. 1400-1408 ◽

Cited By ~ 9

Author(s):

Marjan Bozaghian ◽

Anders Rebbling ◽

Sylvia H. Larsson ◽

Mikael Thyrel ◽

Shaojun Xiong ◽

...

Keyword(s):

Fluidized Bed ◽

Combustion Characteristics ◽

Bubbling Fluidized Bed ◽

Bed Materials

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Two-dimensional mathematical model of liquid fuel combustion in bubbling fluidized bed applied for a fluidized furnace numerical simulation

Thermal Science ◽

10.2298/tsci170922307n ◽

2018 ◽

Vol 22 (2) ◽

pp. 1121-1135

Author(s):

Stevan Nemoda ◽

Milijana Paprika ◽

Milica Mladenovic ◽

Ana Marinkovic ◽

Goran Zivkovic

Keyword(s):

Numerical Simulation ◽

Mathematical Model ◽

Fluidized Bed ◽

Liquid Fuel ◽

Numerical Procedure ◽

Fuel Combustion ◽

Temperature Fields ◽

Field Calculation ◽

Bubbling Fluidized Bed ◽

Three Phases

Lately, experimental methods and numerical simulations are equally employed for the purpose of developing incineration bubbling fluidized bed (BFB) facilities. The paper presents the results of the 2-D CFD model of liquid fuel combustion in BFB, applied for numerical simulation of a fluidized bed furnace. The numerical procedure is based on the two-fluid Euler-Euler approach, where the velocity field of the gas and particles are modeled in analogy to the kinetic gas theory. The proposed numerical model comprises energy equations for all three phases (gas, inert fluidized particles, and liquid fuel), as well as the transport equations of chemical components that are participating in the reactions of combustion and devolatilization. The model equations are solved applying a commercial CFD package, whereby the user submodels were developed for heterogenic fluidized bed combustion of liquid fuels and for interphase drag forces for all three phases. The results of temperature field calculation were compared with the experiments, carried out in-house, on a BFB pilot facility. The numerical experiments, based on the proposed mathematical model, have been used for the purposes of analyzing the impacts of various fuel flow rates, and fluidization numbers, on the combustion efficiency and on the temperature fields in the combustion zone.

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