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Title: A CFD model for biomass combustion in a packed bed furnace

Abstract

Climate change has now become an important issue which is affecting environment and people around the world. Global warming is the main reason of climate change which is increasing day by day due to the growing demand of energy in developed countries. Use of renewable energy is now an established technique to decrease the adverse effect of global warming. Biomass is a widely accessible renewable energy source which reduces CO{sub 2} emissions for producing thermal energy or electricity. But the combustion of biomass is complex due its large variations and physical structures. Packed bed or fixed bed combustion is the most common method for the energy conversion of biomass. Experimental investigation of packed bed biomass combustion is difficult as the data collection inside the bed is challenging. CFD simulation of these combustion systems can be helpful to investigate different operational conditions and to evaluate the local values inside the investigation area. Available CFD codes can model the gas phase combustion but it can’t model the solid phase of biomass conversion. In this work, a complete three-dimensional CFD model is presented for numerical investigation of packed bed biomass combustion. The model describes the solid phase along with the interface between solidmore » and gas phase. It also includes the bed shrinkage due to the continuous movement of the bed during solid fuel combustion. Several variables are employed to represent different parameters of solid mass. Packed bed is considered as a porous bed and User Defined Functions (UDFs) platform is used to introduce solid phase user defined variables in the CFD. Modified standard discrete transfer radiation method (DTRM) is applied to model the radiation heat transfer. Preliminary results of gas phase velocity and pressure drop over packed bed have been shown. The model can be useful for investigation of movement of the packed bed during solid fuel combustion.« less

Authors:
 [1];  [2];  [3];  [1]
  1. Faculty of Science, Engineering and Technology, Swinburne University of Technology, VIC 3122 (Australia)
  2. (Bangladesh)
  3. Department of Mechanical & Chemical Engineering, Islamic University of Technology, Gazipur 1704 (Bangladesh)
Publication Date:
OSTI Identifier:
22608559
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1754; Journal Issue: 1; Conference: ICME 2015: 11. international conference on mechanical engineering, Dhaka (Bangladesh), 18-20 Dec 2015; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
09 BIOMASS FUELS; BIOMASS; CARBON DIOXIDE; CLIMATES; COMBUSTION; DEMAND; ELECTRICITY; EMISSION; ENERGY CONVERSION; GREENHOUSE EFFECT; HEAT TRANSFER; INTERFACES; MASS; PACKED BEDS; PHASE VELOCITY; POROUS MATERIALS; PRESSURE DROP; SIMULATION; SOLID FUELS; SOLIDS; THREE-DIMENSIONAL CALCULATIONS

Citation Formats

Karim, Md. Rezwanul, Department of Mechanical & Chemical Engineering, Islamic University of Technology, Gazipur 1704, Ovi, Ifat Rabbil Qudrat, and Naser, Jamal, E-mail: jnaser@swin.edu.au. A CFD model for biomass combustion in a packed bed furnace. United States: N. p., 2016. Web. doi:10.1063/1.4958417.
Karim, Md. Rezwanul, Department of Mechanical & Chemical Engineering, Islamic University of Technology, Gazipur 1704, Ovi, Ifat Rabbil Qudrat, & Naser, Jamal, E-mail: jnaser@swin.edu.au. A CFD model for biomass combustion in a packed bed furnace. United States. doi:10.1063/1.4958417.
Karim, Md. Rezwanul, Department of Mechanical & Chemical Engineering, Islamic University of Technology, Gazipur 1704, Ovi, Ifat Rabbil Qudrat, and Naser, Jamal, E-mail: jnaser@swin.edu.au. 2016. "A CFD model for biomass combustion in a packed bed furnace". United States. doi:10.1063/1.4958417.
@article{osti_22608559,
title = {A CFD model for biomass combustion in a packed bed furnace},
author = {Karim, Md. Rezwanul and Department of Mechanical & Chemical Engineering, Islamic University of Technology, Gazipur 1704 and Ovi, Ifat Rabbil Qudrat and Naser, Jamal, E-mail: jnaser@swin.edu.au},
abstractNote = {Climate change has now become an important issue which is affecting environment and people around the world. Global warming is the main reason of climate change which is increasing day by day due to the growing demand of energy in developed countries. Use of renewable energy is now an established technique to decrease the adverse effect of global warming. Biomass is a widely accessible renewable energy source which reduces CO{sub 2} emissions for producing thermal energy or electricity. But the combustion of biomass is complex due its large variations and physical structures. Packed bed or fixed bed combustion is the most common method for the energy conversion of biomass. Experimental investigation of packed bed biomass combustion is difficult as the data collection inside the bed is challenging. CFD simulation of these combustion systems can be helpful to investigate different operational conditions and to evaluate the local values inside the investigation area. Available CFD codes can model the gas phase combustion but it can’t model the solid phase of biomass conversion. In this work, a complete three-dimensional CFD model is presented for numerical investigation of packed bed biomass combustion. The model describes the solid phase along with the interface between solid and gas phase. It also includes the bed shrinkage due to the continuous movement of the bed during solid fuel combustion. Several variables are employed to represent different parameters of solid mass. Packed bed is considered as a porous bed and User Defined Functions (UDFs) platform is used to introduce solid phase user defined variables in the CFD. Modified standard discrete transfer radiation method (DTRM) is applied to model the radiation heat transfer. Preliminary results of gas phase velocity and pressure drop over packed bed have been shown. The model can be useful for investigation of movement of the packed bed during solid fuel combustion.},
doi = {10.1063/1.4958417},
journal = {AIP Conference Proceedings},
number = 1,
volume = 1754,
place = {United States},
year = 2016,
month = 7
}
  • A prototype concentric vortex biomass furnace and ram bale feeder were designed and tested. A clear stack was maintained over a turndown ratio of 2:1 and excess air range of 50 to 250%. Stack temperatures ranged up to 700/sup 0/C. Average conversion efficiency was 64%. Maximum heat release was 0.4 MJ/hr.
  • A prototype concentric vortex biomass furnace and ram bale feeder were designed and tested. A clear stack was maintained over a turndown ratio of 2:1 and excess air range of 50 to 250%. Stack temperature ranged up to 700 degrees C. Average conversion efficiency was 64%. Maximum heat release was 0.4 MJ/hr.
  • The authors mathematically simulate the first three levels of the physicochemical processes taking place in a fluidized-bed combustor during the combustion of coal and establish links between these levels. The first of the levels includes the phenomena of heterogeneous and homogeneous kinetics and volatilization occurring at the ionic and molecular level. The second level accounts for the growth and motion of bubbles and for mass and heat transfer between phases in the layer and with the heating surface. The third level includes processes initiated by fields of both external and internal forces such as the hydrodynamics of the bed, circulationmore » of the solid and gas phases, and particle distribution and entrainment. The model makes it possible to calculate coal combustion efficiency and mechanical underfiring. An important difference between this model and existing models is the expanded description of combustion kinetics.« less
  • A numerical model has been developed and validated for the investigation of coal combustion phenomena under blast furnace operating conditions. The model is fully three-dimensional, with a broad capacity to analyze significant operational and equipment design changes. The model was used in a number of studies, including: Effect of cooling gas type in coaxial lance arrangements. It was found that oxygen cooling improves coal burnout by 7% compared with natural gas cooling under conditions that have the same amount of oxygen enrichment in the hot blast. Effect of coal particle size distribution. It was found that during two similar periodsmore » of operation at Port Kembla's BF6, a difference in PCI capability could be attributed to the difference in coal size distribution. Effect of longer tuyeres. Longer tuyeres were installed at Port Kembla's BF5, leading to its reline scheduled for March 2009. The model predicted an increase in blast velocity at the tuyere nose due to the combustion of volatiles within the tuyere, with implications for tuyere pressure drop and PCI capability. Effect of lance tip geometry. A number of alternate designs were studied, with the best-performing designs promoting the dispersion of the coal particles. It was also found that the base case design promoted size segregation of the coal particles, forcing smaller coal particles to one side of the plume, leaving larger coal particles on the other side. 11 refs., 15 figs., 4 tabs.« less
  • The aim of the present paper is to study the gasification and combustion of biomass and waste materials. A model for the analysis of the chemical kinetics of gasification and combustion processes was developed with the main objective of calculating the gas composition at different operating conditions. The model was validated with experimental data for sawdust gasification. After having set the main kinetic parameters, the model was tested with other types of biomass, whose syngas composition is known. A sensitivity analysis was also performed to evaluate the influence of the main parameters, such as temperature, pressure, and air-fuel ratio onmore » the composition of the exit gas. Both oxygen and air (i.e., a mixture of oxygen and nitrogen) gasification processes were simulated.« less