Dissertation > Excellent graduate degree dissertation topics show

Numerical Simulation of Biomass Direct Reburning

Author: LiXiaoLi
Tutor: WuShaoHua
School: Harbin Institute of Technology
Course: Thermal Power Engineering
Keywords: Numerical simulation Biomass Combustion Reburning Direct reburning
CLC: TK16
Type: Master's thesis
Year: 2008
Downloads: 131
Quote: 0
Read: Download Dissertation

Abstract


In this paper a mathematical model of biomass combustion and reburning was developed based on the experimental results of biomass pyrolysis. Numerical simulation of biomass direct reburning based on the built model was performed in CFD program Fluent6.3 by taking a one dimensional drop-tube furnace (DTF) as research object. Combustion and reburning characteristics of biomass rice husk and straw were studied on different stoichiometric ratio and reburning fuel percent, and NO reductions by biomass volatile and char were investigated.The biomass combustion model includes sub-model of moisture evaporation, devolatilization, volatile combustion and char combustion. Diffusion process was used for calculating evaporation, one-step pyrolysis model was used for biomass devolatilization, diffusion-kinetic control model was used for volatile combustion, and multiple-surface reaction model was used for char combustion. Voatile nitrogen and thermal nitrogen produce NO, and volatile and char remove NO were considered.Biomass combustion and NO reduction model were verified experimentally by comparing predicted and experimental results of temperature profile, main volatile compositions profile and NO profile. The compared results show that the developed models can reconstruct biomass combustion and reburning process.Later the effect of reburning zone stoichiometric ratio and reburning fuel percent on biomass combustion and reburning were studied. The results show that burning-out efficiency increases with the increase of reburning zone stoichiometric ratio while NO reduction efficiency decreases when reburning fuel rate is kept constant. The temperature and CO, CO2, CH4 and H2 content along the axial of the furnace increases with the increase of reburning fuel percent when stoichiometric ratio is kept constant. And the same trend happens to NO reduction efficiency.NO removal by volatile is more sensitive to oxygen level, whereas NO removal by carbon on the surface of char is less sensitive to oxygen availability. And NO reduction by homogeneous reaction predominates.The comparisons of reburning characteristics between rice husk and straw indicate that NO reduction efficiency by straw is higher than that by rice husk. Contributors of straw char to the total NO reduction increase when reburning zone stoichiometric ratio increases, while that of straw volatile decrease. When stoichiometric ratio reaches 0.9, contributor of straw char reaches to 46% of the total NO reduction. However the opposite trend happens to rice husk.The studies of characteristics of biomass direct combustion and reburning performed in this paper can provide some suggestions and guides on further explore of biomass clean and efficient combustion and further development of biomass use patterns.

Related Dissertations

  1. The Setting Bases of Working Pressure in LNG Systems and Orthogonal Experiment Design of Heat Exchangers,TQ051.5
  2. Study on Springback of High-Strength Steel Stamping,TG386
  3. Numerical Simulation and Experiment on Hydroforming of Cups with Controllable Radial Pressure,TG386
  4. Research on Technology and Mechanism of Joining Cemented Carbide to Carbon Steel,TG454
  5. Experimental Study on Pyrolysis and Combustion Characteristics of Paint and Tar Based Single Hazardous Wastes,X705
  6. Experimental Research on Influence of Coal Reburning Reaction Conditions on NO_x Reduction by Non-Catalytic Reduction of Ammonia,X701
  7. Pattern Classification of Combustion Modes in Scramjet,V235
  8. Numerical Simulation of Film Cooling in Turbine Cascade with Non-Axisymmetric Endwall Method,V231.3
  9. High Speed Aerodynamic Convection and Coupled Heat Transfer of Complicated Bodies,V215.4
  10. The Analysis on Characteris of Vibration Source about Vertical Vibration of Surrounding Environment Induced by Rail Transit,U211.3
  11. Study on the Heat Transfer Characteristics of Particle Cluster in Circulating Fluidized Bed,TK124
  12. Experimental Study on Combustion Characteristics of Corn Straw in a Fixed Bed,TK16
  13. Numerical Simulation of SNCR Process of a 600MW Utility Boiler,TK222
  14. Numerical Simulation on Pulverized Coal Combustion Process in a 670T/H Tangential Firing Furnace,TK224.11
  15. Experimentation Research for Deoxidize Reaction Process of NO_X Adopt Different Reburnning Fuels,TK227.1
  16. Numerical Simulation on the Combustion Process in the Furnace of a 1000MW Lignite-Fired USC Boiler,TK224.11
  17. Study on Gas-Solid Two-Phase Flow in Spouted Beds,TK173
  18. Experimental Study and Numerical Simulation on Aerodynamic Field of Tangential Bias Swirl Burner,TK223.23
  19. Characteristic Study of Combustion in Central Reverse Flame Chamber,TK223.21
  20. Numerical Simulation and Contrastive Analysis of Labyrinth Seals and Leaf Seals,TK263.2

CLC: > Industrial Technology > Energy and Power Engineering > Thermal engineering, heat > Fuel and combustion
© 2012 www.DissertationTopic.Net  Mobile