An overview of the chemical composition of biomass

Modeling chemical and physical processes of wood and biomass pyrolysis

Biomass combustion in fluidized bed boilers: Potential problems and remedies

Biomass is considered to have potential to be used as an alternative energy source. High carbon content present in biomass converts it into high energy biochar on thermochemical treatment. Among few well established thermochemical technologies for the treatment of biomass and biogenic waste to produce high energy char along with oil and gaseous yield, pyrolysis is the most studied and discussed technique in the recent past. A comparison between the existing techniques is established in the present work. Production of char from the biomass and biogenic wastes is reviewed and it was found that yield of the biochar depends upon the biomass composition like moisture content and presence of cellulose or lignin. Pyrolysis product distribution and their quality strongly depend upon the process parameters. Different biomasses which can be used as raw material in pyrolysis are also reviewed and categorized depending upon their source. Pyrolysis process parameters such as temperature, heating rate, residence time etc. also influence the biochar yield. This study discusses the effect of these process parameters on the production of biochar through pyrolysis of biomass.

Effect of process parameters on production of biochar from biomass waste through pyrolysis: A review

INTRODUCTION Background Fluidized Bed Equipment Features of Fluidized Beds Fluidized Bed and Other Clean Coal Options HYDRODYNAMICS Regimes of Fluidization Fast Fluidized Bed Hydrodynamic Regimes in a CFB Hydrodynamic Structure of Fast Beds Gas-Solid Mixing Scale-Up FLUIDIZED BED GASIFICATION Types of Gasifiers Theory Effect of Operating Parameters on Gasification Effect of Feed Properties on Gasification Fluidized Bed Gasification Examples of Some Fluidized Bed Gasifiers Gas Cleaning Design Methods Modeling of Fluidized Bed Gasification Appendix 3A: Estimating Equilibrium Gas Composition Appendix 3B: An Example of a Fluidized Bed Biomass Gasifier COMBUSTION Stages of Combustion Factors Affecting Combustion Efficiency Combustion in Bubbling Fluidized Bed Boilers Combustion in Circulating Fluidized Bed Boilers Biomass Combustion EMISSIONS Air Pollution Sulfur Dioxide Emission Nitrogen Oxide Emission Nitrous Oxide Emission Mercury Emission Carbon Monoxide Emission Carbon Dioxide Emission Emission of Trace Organics Particulate Emission HEAT TRANSFER Gas-to-Particle Heat Transfer Heat Transfer in Circulating Fluidized Beds Heat Transfer in Bubbling Fluidized Bed Freeboard Heat Transfer in Bubbling Fluidized Beds Heat Transfer in Commercial-Size CFB Boilers BUBBLING FLUIDIZED BED BOILER Description of a BFB Boiler Features of BFB Boilers Thermal Design of Bubbling Fluidized Bed Boilers Combustion in Bubbling Fluidized Bed Furnace Design Start-Up Procedure and Control Some Operational Problems and Remedies Design of Feed Systems for BFB Bed Boiler CIRCULATING FLUIDIZED BED BOILER General Arrangement Types of CFB Boilers Non-CFB Solid Circulation Boilers Combustion in a Circulating Fluidized Bed Furnace Design of CFB Boilers Furnace Design Design of Heating Surfaces Auxiliary Power Consumption Control of CFB Boilers Supercritical CFB Boiler MATERIAL ISSUES Material Selection Criteria Erosion Potential Corrosion Potentials Steels Used in Fluidized Bed Boilers Refractory and Insulations Expansion Joints SOLID HANDLING SYSTEMS FOR FLUIDIZED BEDS Solid Handling Systems Biomass Handling Systems Feed System for Bubbling Beds Feed System for Circulating Fluidized Beds Design of Pneumatic Transport Lines for Solids AIR DISTRIBUTION GRATE Distributor Plates Operation of Distributors Design Methods Practical Considerations GAS-SOLID SEPARATORS Cyclones Impact Separator Inertial Separators SOLID RECYCLE SYSTEMS Types of Non-mechanical Valves Principles of Operation Design of Loop-Seal Design of L-Valve Practical Considerations Nomenclature References APPENDIX 1: CHARACTERISTICS OF SOLID PARTICLES APPENDIX 2: STOICHIOMETRIC CALCULATIONS APPENDIX 3: SIMPLIFIED MODEL FOR SULFUR CAPTURE APPENDIX 4: TABLES OF DESIGN DATA

Combustion and gasification in fluidized beds

Combustion of agricultural residues

Combustion of coffee husks

19% of the sewage sludge produced in Germany is presently incinerated. The emissions from sludge combustion in Germany are regulated by the 17th Regulation of the Federal Immission Protection Law. These emission limits can only be met, however, with a large technical effort. To fulfill the mercury emission limit of 0.05 mg/m3 (dry, standard conditions) in particular, special measures are necessary. This paper presents an overview on the various measures for emission control which are used at German sludge incineration plants. Furthermore, future trends of thermochemical sludge treatment in Germany, including co-combustion in power stations and gasification processes, are discussed.

Emissions from Sewage Sludge Combustion in Germany - Status and Future Trends -

The fluidized bed sewage sludge incineration plant of the city of Hamburg started its operation in May 1997. In cooperation with Hamburger Stadtentwaesserung the Technical University Hamburg-Harburg undertook an experimental program to measure the mass balance of mercury across this plant. During the first months of full operation the mercury concentrations in the flue gas and in the solid residues were measured. The measurements show that the concentration in the raw flue gas is between 500 to 950 {micro}g/m{sup 3} and part of the elemental mercury depends on the chlorine content of the fuel. The concentration of the mercury in the flue gas is reduced over the first scrubber to 35--460 {micro}m/m{sup 3}. Some 77% of the mercury input are found in the sediment separated from the liquid of the acid scrubber. It is remarkable that the concentration of the elemental mercury increases while the gas passes through the scrubber. The concentration of mercury in the cleaned stack gas is less than 40 {micro}g/m{sup 3}. Since it is generally known that it is not easy to meet the limit of 50 {micro}g mercury per m{sup 3} (standard conditions, dry basis) of flue gas which is set by the German regulationsmore » for waste incineration, the measurements provide a comprehensive picture of the fate of mercury in a fluidized bed sludge incineration plant.« less

M. Saenger

Papers

Combustion of agricultural residues

Combustion of coffee husks

Emissions from Sewage Sludge Combustion in Germany - Status and Future Trends -

Concentrations and mass balance of mercury in a fluidized bed sewage sludge incineration plant