Improving Biomass Fuels Through Water Washing Pre-Treatment
Paper instructions:
1 PROJECT TITLE
Improving Biomass Fuels Through Water Washing Pre-Treatment
2 INDUSTRY COLLABORATION
No industrial collaboration
3 SYNOPSIS
3.1 Introduction (mainly the goals of the analysis)
Biomass is increasingly being considered for the production of renewable energy. One of the key challenges with utilising biomass for direct or co-combustion arises from the large amount of alkali metal content inherently present in these fuels. Potassium and sodium, along with sulphur and chlorine, influence ash chemistry and the behaviour of the fuel in terms of its tendency to corrode equipment and cause slagging and fouling. The main causes of these undesirable slagging effects are attributed to the reactions of alkali metals with silica to form alkali silicates, which melt or soften at temperatures as low as 700 °C, and the reactions of alkali metals with sulphur, which form alkali sulphates on heat transfer and combustor surfaces. Demineralisation of the fuel, by water washing is a simple and effective method for removing a large fraction of the fuel mineral content, thereby reducing the above-mentioned ash problems.
This project will focus on optimising a demineralisation water washing regime to improve a woody biomass fuel.
3.2 Research questions
This project will attempt to answer the following questions:
• What is the relationship between washing time and amount of metals removed?
• What is the optimum volume of water to fuel?
• What is the relationship between agitation and mineral removal?
• Can water be re-circulated while still achieving acceptable demineralisation?
3.3 Suggested reading to start off the project
[1] D. L. Klass, Biomass for renewable energy, fuels, and chemicals . San Diego: Academic Press, 1998.
[2] A. Saddawi, J. M. Jones, A. Williams, and C. Le Coeur, “Commodity Fuels from Biomass through Pretreatment and Torrefaction: Effects of Mineral Content on Torrefied Fuel Characteristics and Quality,” Energy & Fuels, vol. 26, no. 11, pp. 6466–6474, Jan. 2012.
[3] D. Vamvuka and S. Sfakiotakis, “Effects of heating rate and water leaching of perennial energy crops on pyrolysis characteristics and kinetics,” Renewable Energy, vol. xx in-pres, 2011.
3.4 Methodology
The student will perform a series of washing treatments of a biomass wood-chip fuel in a beaker with an over-head stirrer. Deionised water will be used and the leachate will be tested for mineral content with liquid chromatography. Thermogravimetric analysis of the washed fuels will also be performed to determine effects of washing on combustion kinetics.
3.5 Expected results
Some expected results will include tables and plots of concentrations of metals removed from each method of washing along with some thermogravimetric analysis comparisons such as:
3.6 Research outcomes
Some of the research outcomes will include a case study or background research for other student projects.
4 PROJECT ELEMENTS
4.1 Where the raw data comes from?
The data will be experimentally derived by the student.
4.2 Types of measurement required?
Thermogravimetric analysis, Liquid chromatography of leachate.
4.3 Types of experiments or design?
Water washing of fuels, filtering and combustion, solid fuels milling and sieving.
4.4 Does the student need supervising during measurement/experiment?
The student will be trained to use the TGA machine and supervised whiles being trained. The student will also be trained to use other lab equipment such as shredder, ball mill, sieve shaker etc.
4.5 Tools/equipment required?
Thermogravimetric analyser, balance, sample storage bottles and bags, spatulas etc. Size reduction equipment (mortar and pestle), ball mill, sieve shaker, over-head stirrer. Sieves. Compressed air and nitrogen. Water syringe pump. Access to Excel for post run data analysis. Gloves and PPE and consumables.
4.6 Do you need a laboratory?
New Biofuels laboratory will be utilised.
4.7 Do you need other resources/equipment/software not in the school?
No other equipment necessary.