On Biomass Milling for Power Generation
On Biomass Milling for Power Generation
Biomass and Fossil Fuel Research Alliance (BF2RA), with main supervision from Mr Stephen Lormor from EDF Energy plc
The research provided extensive novel characterisation on densified biomass before and after milling. The study analysed 9 densified biomasses, 2 non-densified biomasses, and a sample coal in five different mills; planetary ball mill, Hardgrove Grindability Index testing mill, Bond Work Index ball mill, hammer mill, and a ring-roller mill.
It was found that milling had little impact on particle shape even when an order of magnitude difference was seen in the particle size. Particle shape is inherent to particles which comprise a pellet, and is determined by the pre-densified comminution processes. Milling had little impact on herbaceous or wood pellets compositional particles. Olive cake had the most spherical of all the materials and thermal pre-treatments of woody biomass not only see a significant improvement in grindability in all mills, but also enhanced shape factors.The Hardgrove Grindability Index is a poor indicator of the grindability of biomass in a vertical spindle mill. The Bond Work Index can be used to analyse the choking potential of biomass pellets prior to full scale mill trials. To optimise milling in a coal mills, biomass pellets should be composed of particles close to the required size so that only the pellet comminution stage occurs. A novel study of the milling behaviour of densified biomass in a laboratory scale ring-roller mill with dynamic classification was conducted. The milling studies showed that knowledge of a materials critical particle size for comminution through compression is essential to understand its milling behaviour in different mills.
The results not only provide new insight and addresses significant gaps in knowledge, they also provide useful and practical guidance for addressing operational issues and ways to optimise biomass comminution in laboratory and full scale mills.
Student attractions of the EngD Centre
The EngD centre has provided me with a unique and fantastic opportunity to become one of the world leading researchers in the power generation sector. The projects are industrially focused, which means they are addressing real and current challenges facing power generators. The close links with industry throughout the project have allowed me to apply my laboratory results to full scale applications and provide helpful results with an academic and industrial perspective. The diverse group of students, academics and industrialists involved in the centre means that expertise in all areas can be called on throughout the project. The structured training provided throughout the programme gives students a holistic overview of the power generating sector in terms of political, policy, societal, economical perspectives in addition to technical knowledge. The centre also engages in public engagement with schools and the wider community, which allows students to develop the essential communication skills which engineers need to effectively communicate the benefits of new technologies to the general public. Finally, the centre has encouraged and facilitated extensive opportunities to communicate my research to my peers through academic and industrial conferences across the word and publish my work in prestigious peer reviewed journals.
Prizes and awards
- Winner of Best Poster for Research Impact at the University of Nottingham Faculty of Engineering Research Showcase May 2014
- Winner of the Student Award at the 22nd EU Biomass Conference & Exhibition for excellent research work in the field of biomass in June 2015
- Winner of the University of Nottingham Dean Moore Research Scholarship 2015
- Winner of the British Flame Research Committee award for best presentation at the BF2RA Student Research Project Session of the 64th Energy Science Lecture – October 2015
Travel grants awarded
- Midlands Energy Graduate School (MEGS) Travel Grant July 2013- £500
- University of Nottingham Science, Technology & Society (STS) Priority Group Travel Bursary July 2014 - £500
- Coal Research Forum (CRF) Travel Bursary November 2014 -£140
- University of Nottingham Graduate School Travel Bursary April 2015 - £600
- Society of Chemical Industry (SCI) Richardson Travel Bursary May 2015 - £850
As concerns regarding the impact of climate change intensify, legislation is increasingly targeting the highest producers of emissions. Biomass combustion in coal fired power stations offers a low cost way to both extend the life of coal fired power stations and reduce emissions. Existing coal power plants want to use their existing equipment – but they are designed for coal, which is a hard brittle material. Biomass is an impact absorbent material and doesn’t mill in the same way, which leads to mill blockages, reduced thermal output, fires and explosions. By working with a consortium of power generators through the Biomass and Fossil Fuel Research Alliance (BF2RA), I have been investigating the milling behaviour of biomass in mills used in the power sector. A wide range of biomasses, from straws, wood, agricultural wastes, to pre-treated biomasses, were analysed in several mills at lab scale and full scale. The aim of this project is to gain a greater understanding of milling behaviour of different biomasses in different mills. The project outcomes will help power generators make more informed decisions on biomass selection, as well as identify potential operational and maintenance issues, and ultimately reduce carbon emissions from coal fired power stations.
Conference proceedings and Publications
- Williams, O., Eastwick, C., Lester, E., Giddings, D., & Lormor, S. (2015). The Mechanical Response of Biomass Pellets in Standard Coal Grindability Tests. In: ICCS&T/ACSE 2015
- Williams, O., Eastwick, C., Lester, E., Giddings, D., & Lormor, S. (2015). Paper Number 152180910: Impact of Mill Type on Biomass Mill Behavior. In:2015 ASABE Annual International Meeting.
- Williams O, Eastwick C, Lester E, Giddings D, Byrne N. 2014 Bond Index & Hardgrove Grindability Index Tests For Biomass & Coal 10th ECCRIA (European Conference on Coal Research and its Applications) 49
- Williams O, Eastwick C, Lester E, Giddings D, Byrne N. 2014 The impact of moisture on the milling behaviour of different biomasses. In: 22nd European Biomass Conference and Exhibition. 467–71.
- Williams, O., Eastwick, C., Graham, S., Cooper, A., 2013. The Impact of Storage on the Optimisation of Milling of Biomasses used in Power Generation. In: 3rd IEA CCC Workshop on Co-firing Biomass with Coal
- Williams, O., Eastwick, C., Lester, E., Giddings, D., Byrne, N., 2013. Optimisation of Biomass Milling for Conveyance and Combustion. In: 21st European Biomass Conference and Exhibition. 1164 – 1166
- Williams, O., Eastwick, C., Kingman, S., Giddings, D., Lormor, S., & Lester, E. Investigation into the applicability of Bond Work Index (BWI) and Hardgrove Grindability Index (HGI) tests for several biomasses compared to Colombian La Loma coal. Fuel. 158. (2015): 379-387 (Impact Factor 3.520)
- Dawson, Robert, Lee A. Stevens, Orla SA Williams, Weixing Wang, Benjamin O. Carter, Sam Sutton, Trevor C. Drage, Frédéric Blanc, Dave J. Adams, and Andrew I. Cooper. ‘Dry bases’: carbon dioxide capture using alkaline dry water. Energy & Environmental Science 7, no. 5 (2014): 1786-1791. (Impact Factor 20.523)
Oral and poster presentations
Presentation title: Utilisation of Fossil fuel and Biomass – Fuel Preparation and Transportation at the EPSRC Engineering Doctoral Centre Summer School, Shanghai, China. July 2012
Presentation title: The Impact of Storage on the Optimisation of Milling of Biomasses used in Power Generation at the IEA Clean Coal Centre 3rd Workshop on Co-firing Biomass with Coal, Groningen, Netherlands. June 2013
Presentation title: Biomass and the Carbon Neutral Economy Conference: Women’s Engineering Society Annual Conference ‘Harnessing the Energy’, Institution of Mechanical Engineers (IMechE) Head Quarters, London, UK. September 2013
Presentation title: Factors Influencing Biomass Milling Optimisation at the Midlands Energy Graduate School (MEGS) IV Christmas Conference, University of Birmingham, UK. December 2013
Presentation title: The impact of moisture on the milling behaviour of different biomasses at the 22nd European Biomass Conference and Exhibition, Hamburg, German. June 2014
Presentation title: Bond Index & Hardgrove Grindability Index Tests For Biomass & Coal at the 10th ECCRIA (European Conference on Coal Research and its Applications), University of Hull, UK. September 2014
Presentation title: Impact of Mill Type on Biomass Mill Behavior at the American Society of Agricultural & Biological Engineers (ASABE) Annual International Meeting, New Orleans, Louisiana, USA. June 2015
Presentation title: On Biomass Milling for Power Generation at the BF2RA Student Research Project Session of the 64th Energy Science Lecture, Chartered Institute of Accountants, London, UK. October 2015
Presented in Absentia by Prof Ed Lester:
Presentation title: The Mechanical Response of Biomass Pellets in Standard Coal Grindability TestsConference: International Conference on Coal Science & Technology 2015 (ICCS&T 2015), Melbourne, Australia. September 2015
Poster title: Optimisation of Biomass Milling for Conveyance and Combustion at the 21st European Biomass Conference and Exhibition, Copenhagen, Denmark, June 2013
Poster title: Optimisation of Biomass Milling for Conveyance and Combustion at the IEA GHG 7th International CCS Summer School, University of Nottingham, UK, July 2013
Poster title: Optimisation of Biomass Milling for Conveyance and Combustion at the Energy CDT Network @ Energy Futures Student Research Conference, Imperial College, London, UK. September 2013
Poster title: Impact of Moisture on the Milling Behaviour of Spanish Olive Cake at the International Bioenergy Conference 2014, Manchester, UK. March 2014
Poster title: Optimisation of Biomass Milling for the Power Sector at the University of Nottingham Faculty of Engineering Research Showcase. May 2014
Poster title: Biomass or Bust? at the University of Nottingham Research Showcase. June 2014
International conferences attended
- IEA Clean Coal Centre 2nd Workshop on Co-firing Biomass with Coal, Copenhagen, Denmark, March 2012
- Applied Energy Expert Forum, Ningbo, China, July 2012
- 21st European Biomass Conference and Exhibition, Copenhagen, Denmark, 3-7th June 2013
- IEA Clean Coal Centre 3rd Workshop on Co-firing Biomass with Coal, Groningen, Netherlands, June 2013
- 22nd European Biomass Conference and Exhibition, Hamburg, Germany, June 2014
- American Society of Agricultural & Biological Engineers (ASABE) Annual International Meeting, New Orleans, Louisiana, USA, June 2015
I am starting a post-doctoral research position with the Microwave Process Engineering Group in the Division of Energy and Sustainability at the University of Nottingham.