Jim Swithenbank | The University of Sheffield (original) (raw)
Papers by Jim Swithenbank
A convenient and rapid technique based on a collimated laser beam, Fourier transform lens, and ph... more A convenient and rapid technique based on a collimated laser beam, Fourier transform lens, and photographic plate or concentric ring photodetector is proposed for measuring the size distribution of droplets and particles from diffracted light energy measurements. The major advantage of this technique is that the diffraction pattern is independent of particle and droplet motion. Analysis of fuel sprays by
Energy Conversion and Management, 2014
ABSTRACT Reducing carbon emissions from buildings is vital to achieve goals for avoiding dangerou... more ABSTRACT Reducing carbon emissions from buildings is vital to achieve goals for avoiding dangerous climate change, and supplying them with low-carbon heat is essential. In the UK, the development of heat networks for supplying low-carbon heat is being encouraged for urban areas where there is high heat demand density. This paper investigates heat demand variability, the role of heat networks and combined heat and power (CHP) in satisfying this demand, and finally the advantages of using heat storage in the system. Building heat demands from 50 buildings were analysed at a half-hour resolution with modelling to determine CHP operation patterns with and without heat storage. Daily total heat demand was found to vary from 25% of the full-year average in summer months up to 235% of the average on the coldest days in winter. The heat demand was shown to correlate to outdoor temperatures measured with the degree-day parameter, except for approximately 100 days during the warmest part of the year falling outside the heating season. Sharp spikes in heat demand were seen at the half-hourly time scale coinciding with the switching on of heating systems in some buildings with consequences for building energy supply options. It was shown that for an annual heat demand of 40,000 MW h, the use of thermal storage can significantly increase the running time of a CHP energy centre with 4 MW capacity designed to supply this demand. The cost savings resulting from increased on-site heat and electricity production resulted in a payback period for heat storage investment of under four years with further benefits if it can assist other heat sources on the heat network. Environmental advantages of using heat storage included further carbon dioxide emission reductions of 1000–1500 tonnes per year depending upon the CHP configuration.
Process Safety and Environmental Protection, 2001
Waste Management, 1991
... The temperature contours for this design are shown in Fig. 10. ... leaving the boiler are red... more ... The temperature contours for this design are shown in Fig. 10. ... leaving the boiler are reduced by nearly 200 K by the heat transfer effects of the water-cooled baffle ... The temperature dis-tribution throughout the boiler convective tube bank and the boiler exit are found to be nearly ...
Environmental Progress, 1998
... to give clinkerproblem and affect the sintering process offlwsii. ... A key aspect of this wo... more ... to give clinkerproblem and affect the sintering process offlwsii. ... A key aspect of this work is the technique used to ensure the energy efficiency of the ... However, all the municipal waste combustionprocess effluents, including stack emission, solid residues, and waste water must be ...
Progress in Computational Fluid Dynamics, 2006
Sheffield University Waste Incineration Centre (SUWIC), Department of Chemical and Process Engine... more Sheffield University Waste Incineration Centre (SUWIC), Department of Chemical and Process Engineering, Sheffield University, Mappin Street, Sheffield, S1 3JD, UK Fax: 0044-114-2227501 E-mail: ybyang@shef.ac.uk E-mail: j.goodfellow@shef.ac.uk E-mail: vnsharifi@shef.ac.uk ...
Journal of Analytical Atomic Spectrometry, 2005
ABSTRACT A mobile continuous emissions monitoring laboratory, based on ICP-OES technology, was us... more ABSTRACT A mobile continuous emissions monitoring laboratory, based on ICP-OES technology, was used to study temporal variations in metal concentrations in the flue gas of a waste-to-energy plant. The concentrations of over 30 elements were monitored prior to flue gas clean-up. Despite harsh analytical conditions, with high particulate loading, variable gas matrix and high concentrations of numerous elements, semi-quantitative measurements were made. Realistic detection limits in the range 0.007–0.06 mg m−3 were achieved. For many volatile metals, significant variations (4–18 mg m−3 for Na, 0–0.18 mg m−3 for Cd) were observed, and were linked to properties of the metal in question, to incinerator operating conditions, and to variations in the waste feed charge. The concentrations of some metals were attributable to specific sources in the waste. It was concluded that better waste segregation could significantly reduce the concentration of toxic metals in the incinerator residues, and where concentration spikes were detected, accurate real-time metal concentration measurements had the potential to provide feedback to clean-up systems, thereby minimising the overall environmental effect.
Environmental Progress, 1994
International Journal of Environmental Analytical Chemistry, 2002
The potential of using tree bark as a passive sampling medium for detection of Polychlorinated di... more The potential of using tree bark as a passive sampling medium for detection of Polychlorinated dibenzo- p -dioxins and furans (PCDD/F) in an urban environment has been investigated. Bark samples (∼ 30 g) were extracted with toluene using accelerated solvent extraction. Extracts were then cleaned up via a multi-bed silica column and a Florisil column followed by GC-MS/MS analysis. It
Environmental Progress, 2002
ABSTRACT A major problem in the operation of incinerators is the build-up of slag on the walls in... more ABSTRACT A major problem in the operation of incinerators is the build-up of slag on the walls in the throat region of the plant between the furnace chamber and the radiation shaft. This slag can accumulate to a thickness of about one meter, with a weight of several tonnes. This accumulation reduces the availability of the plant, and poses a safety problem, since injury can occur when the material is removed by pneumatic drills during maintenance operations. The excessive downtime, labor, and other economic costs of the slag removal can be minimized by developing a novel, no-moving-part jet deflector that can prevent or minimize the accumulation of slag around the jets. The jet deflector was developed and designed by understanding the fundamental principles of the fluid and particle dynamics around the high-speed jet.Two small-scale laboratory rigs were constructed for this study. The first rig was a wind tunnel specially designed to minimize the turbulent intensity at the main flow inlet. The second was a combustion rig fitted with an ash/burner injection system, a mobile phone networked particle monitor, and a removable refractory panel onto which the jet and deflector were fitted. An extensive series of laboratory experiments were carried out on both rigs. In parallel with the laboratory investigation, computational fluid dynamic (CFD) analysis of the flow field around the jet and deflector under the same experimental conditions were also conducted. Optimization work on the deflector design was also carried out. Fully optimized jet deflectors were then manufactured and tested in a UK municipal waste incinerator plant. Visual inspections of the jets before and after the deflectors were fitted showed a very significant reduction in the slag formation.
Waste Management, 2002
The rising popularity of incineration of municipal solid waste (MSW) calls for detailed mathemati... more The rising popularity of incineration of municipal solid waste (MSW) calls for detailed mathematical modelling and understanding of the incineration process. In this paper, governing equations for mass, momentum and heat transfer for both solid and gaseous phases in a moving bed in a solid-waste incineration furnace are described and relevant sub-models are presented. The burning rates of volatile hydrocarbons in the moving bed of solids are limited not only by the reaction kinetics but also the mixing of the volatile fuels with the under-fire air. The mixing rate is averaged across a computation cell and correlated to a number of parameters including local void fraction of the bed, gas velocity and a length scale comparable to the particle size in the bed. A correlation equation is also included to calculate the mixing in the freeboard area immediately next to the bed surface. A small-scale fixed bed waste incinerator was built and test runs were made in which total mass loss from the bed, temperature and gas composition at different locations along the bed height were measured. A 2-D bed-modelling program (FLIC) was developed which incorporates the various sub-process models and solves the governing equations for both gases and solids. Thermal and chemical processes are mainly confined within a layer about 5-9 times in thickness of the averaged particle size in the burning bed. For a large part of the burning process, the total mass loss rate was constant until the solid waste was totally dried out and a period of highly rising CO emission followed. The maximum bed temperature was around 1200 K. The whole burning process ended within 60 min. Big fluctuations in species concentration were observed due to channelling and subsequent 'catastrophic' changes in the local bed conditions. Reasonably good agreement between modelling and measurements has been achieved. Yet the modelling work is complicated by the channelling phenomenon in the bed. Numerical simulations without consideration of the channelling effect produced very good agreement with experiments concerning the total mass loss, but significant discrepancy exists for temperature and gas composition profiles. Transient phenomena such as the breaking of waste particles and the "catastrophic" creation of new burning channels occurring during waste incineration is a vital area requiring further investigation at the fundamental level. The underlying theory of bed behaviour must be extended to include these transient events.
Progress in Computational Fluid Dynamics, An International Journal, 2007
Department of Chemical and Process Engineering, Sheffield University Waste Incineration Centre (S... more Department of Chemical and Process Engineering, Sheffield University Waste Incineration Centre (SUWIC), Sheffield University, Mappin Street, Sheffield, S1 3JD, UK Fax: 0044 -114-2227501 E-mail: ybyang@shef.ac.uk E-mail: vnyang@shef.ac.uk E-mail: j.swithenbank@shef.ac.uk ...
Progress in Computational Fluid Dynamics, An International Journal, 2007
... In order to be used for the reactor design, chemical reaction kinetics and transport phenomen... more ... In order to be used for the reactor design, chemical reaction kinetics and transport phenomena has been coupled to model conventional gasifiers (Groeneveld and van Swaaij, 1980; Manurung and Beenackers, 1994; Reed and Markson, 1985), but these works were still based ...
Progress in Computational Fluid Dynamics, An International Journal, 2007
Department of Chemical and Process Engineering, Sheffield University Waste Incineration Centre (S... more Department of Chemical and Process Engineering, Sheffield University Waste Incineration Centre (SUWIC), Sheffield University, Mappin Street, Sheffield, S1 3JD, UK Fax: 0044 -114-2227501 E-mail: ybyang@Sheffield.ac.uk E-mail: vnsharifi@shef.ac.uk E-mail: ...
Process Safety and Environmental Protection, 2005
Process Safety and Environmental Protection, 2000
A convenient and rapid technique based on a collimated laser beam, Fourier transform lens, and ph... more A convenient and rapid technique based on a collimated laser beam, Fourier transform lens, and photographic plate or concentric ring photodetector is proposed for measuring the size distribution of droplets and particles from diffracted light energy measurements. The major advantage of this technique is that the diffraction pattern is independent of particle and droplet motion. Analysis of fuel sprays by
Energy Conversion and Management, 2014
ABSTRACT Reducing carbon emissions from buildings is vital to achieve goals for avoiding dangerou... more ABSTRACT Reducing carbon emissions from buildings is vital to achieve goals for avoiding dangerous climate change, and supplying them with low-carbon heat is essential. In the UK, the development of heat networks for supplying low-carbon heat is being encouraged for urban areas where there is high heat demand density. This paper investigates heat demand variability, the role of heat networks and combined heat and power (CHP) in satisfying this demand, and finally the advantages of using heat storage in the system. Building heat demands from 50 buildings were analysed at a half-hour resolution with modelling to determine CHP operation patterns with and without heat storage. Daily total heat demand was found to vary from 25% of the full-year average in summer months up to 235% of the average on the coldest days in winter. The heat demand was shown to correlate to outdoor temperatures measured with the degree-day parameter, except for approximately 100 days during the warmest part of the year falling outside the heating season. Sharp spikes in heat demand were seen at the half-hourly time scale coinciding with the switching on of heating systems in some buildings with consequences for building energy supply options. It was shown that for an annual heat demand of 40,000 MW h, the use of thermal storage can significantly increase the running time of a CHP energy centre with 4 MW capacity designed to supply this demand. The cost savings resulting from increased on-site heat and electricity production resulted in a payback period for heat storage investment of under four years with further benefits if it can assist other heat sources on the heat network. Environmental advantages of using heat storage included further carbon dioxide emission reductions of 1000–1500 tonnes per year depending upon the CHP configuration.
Process Safety and Environmental Protection, 2001
Waste Management, 1991
... The temperature contours for this design are shown in Fig. 10. ... leaving the boiler are red... more ... The temperature contours for this design are shown in Fig. 10. ... leaving the boiler are reduced by nearly 200 K by the heat transfer effects of the water-cooled baffle ... The temperature dis-tribution throughout the boiler convective tube bank and the boiler exit are found to be nearly ...
Environmental Progress, 1998
... to give clinkerproblem and affect the sintering process offlwsii. ... A key aspect of this wo... more ... to give clinkerproblem and affect the sintering process offlwsii. ... A key aspect of this work is the technique used to ensure the energy efficiency of the ... However, all the municipal waste combustionprocess effluents, including stack emission, solid residues, and waste water must be ...
Progress in Computational Fluid Dynamics, 2006
Sheffield University Waste Incineration Centre (SUWIC), Department of Chemical and Process Engine... more Sheffield University Waste Incineration Centre (SUWIC), Department of Chemical and Process Engineering, Sheffield University, Mappin Street, Sheffield, S1 3JD, UK Fax: 0044-114-2227501 E-mail: ybyang@shef.ac.uk E-mail: j.goodfellow@shef.ac.uk E-mail: vnsharifi@shef.ac.uk ...
Journal of Analytical Atomic Spectrometry, 2005
ABSTRACT A mobile continuous emissions monitoring laboratory, based on ICP-OES technology, was us... more ABSTRACT A mobile continuous emissions monitoring laboratory, based on ICP-OES technology, was used to study temporal variations in metal concentrations in the flue gas of a waste-to-energy plant. The concentrations of over 30 elements were monitored prior to flue gas clean-up. Despite harsh analytical conditions, with high particulate loading, variable gas matrix and high concentrations of numerous elements, semi-quantitative measurements were made. Realistic detection limits in the range 0.007–0.06 mg m−3 were achieved. For many volatile metals, significant variations (4–18 mg m−3 for Na, 0–0.18 mg m−3 for Cd) were observed, and were linked to properties of the metal in question, to incinerator operating conditions, and to variations in the waste feed charge. The concentrations of some metals were attributable to specific sources in the waste. It was concluded that better waste segregation could significantly reduce the concentration of toxic metals in the incinerator residues, and where concentration spikes were detected, accurate real-time metal concentration measurements had the potential to provide feedback to clean-up systems, thereby minimising the overall environmental effect.
Environmental Progress, 1994
International Journal of Environmental Analytical Chemistry, 2002
The potential of using tree bark as a passive sampling medium for detection of Polychlorinated di... more The potential of using tree bark as a passive sampling medium for detection of Polychlorinated dibenzo- p -dioxins and furans (PCDD/F) in an urban environment has been investigated. Bark samples (∼ 30 g) were extracted with toluene using accelerated solvent extraction. Extracts were then cleaned up via a multi-bed silica column and a Florisil column followed by GC-MS/MS analysis. It
Environmental Progress, 2002
ABSTRACT A major problem in the operation of incinerators is the build-up of slag on the walls in... more ABSTRACT A major problem in the operation of incinerators is the build-up of slag on the walls in the throat region of the plant between the furnace chamber and the radiation shaft. This slag can accumulate to a thickness of about one meter, with a weight of several tonnes. This accumulation reduces the availability of the plant, and poses a safety problem, since injury can occur when the material is removed by pneumatic drills during maintenance operations. The excessive downtime, labor, and other economic costs of the slag removal can be minimized by developing a novel, no-moving-part jet deflector that can prevent or minimize the accumulation of slag around the jets. The jet deflector was developed and designed by understanding the fundamental principles of the fluid and particle dynamics around the high-speed jet.Two small-scale laboratory rigs were constructed for this study. The first rig was a wind tunnel specially designed to minimize the turbulent intensity at the main flow inlet. The second was a combustion rig fitted with an ash/burner injection system, a mobile phone networked particle monitor, and a removable refractory panel onto which the jet and deflector were fitted. An extensive series of laboratory experiments were carried out on both rigs. In parallel with the laboratory investigation, computational fluid dynamic (CFD) analysis of the flow field around the jet and deflector under the same experimental conditions were also conducted. Optimization work on the deflector design was also carried out. Fully optimized jet deflectors were then manufactured and tested in a UK municipal waste incinerator plant. Visual inspections of the jets before and after the deflectors were fitted showed a very significant reduction in the slag formation.
Waste Management, 2002
The rising popularity of incineration of municipal solid waste (MSW) calls for detailed mathemati... more The rising popularity of incineration of municipal solid waste (MSW) calls for detailed mathematical modelling and understanding of the incineration process. In this paper, governing equations for mass, momentum and heat transfer for both solid and gaseous phases in a moving bed in a solid-waste incineration furnace are described and relevant sub-models are presented. The burning rates of volatile hydrocarbons in the moving bed of solids are limited not only by the reaction kinetics but also the mixing of the volatile fuels with the under-fire air. The mixing rate is averaged across a computation cell and correlated to a number of parameters including local void fraction of the bed, gas velocity and a length scale comparable to the particle size in the bed. A correlation equation is also included to calculate the mixing in the freeboard area immediately next to the bed surface. A small-scale fixed bed waste incinerator was built and test runs were made in which total mass loss from the bed, temperature and gas composition at different locations along the bed height were measured. A 2-D bed-modelling program (FLIC) was developed which incorporates the various sub-process models and solves the governing equations for both gases and solids. Thermal and chemical processes are mainly confined within a layer about 5-9 times in thickness of the averaged particle size in the burning bed. For a large part of the burning process, the total mass loss rate was constant until the solid waste was totally dried out and a period of highly rising CO emission followed. The maximum bed temperature was around 1200 K. The whole burning process ended within 60 min. Big fluctuations in species concentration were observed due to channelling and subsequent 'catastrophic' changes in the local bed conditions. Reasonably good agreement between modelling and measurements has been achieved. Yet the modelling work is complicated by the channelling phenomenon in the bed. Numerical simulations without consideration of the channelling effect produced very good agreement with experiments concerning the total mass loss, but significant discrepancy exists for temperature and gas composition profiles. Transient phenomena such as the breaking of waste particles and the "catastrophic" creation of new burning channels occurring during waste incineration is a vital area requiring further investigation at the fundamental level. The underlying theory of bed behaviour must be extended to include these transient events.
Progress in Computational Fluid Dynamics, An International Journal, 2007
Department of Chemical and Process Engineering, Sheffield University Waste Incineration Centre (S... more Department of Chemical and Process Engineering, Sheffield University Waste Incineration Centre (SUWIC), Sheffield University, Mappin Street, Sheffield, S1 3JD, UK Fax: 0044 -114-2227501 E-mail: ybyang@shef.ac.uk E-mail: vnyang@shef.ac.uk E-mail: j.swithenbank@shef.ac.uk ...
Progress in Computational Fluid Dynamics, An International Journal, 2007
... In order to be used for the reactor design, chemical reaction kinetics and transport phenomen... more ... In order to be used for the reactor design, chemical reaction kinetics and transport phenomena has been coupled to model conventional gasifiers (Groeneveld and van Swaaij, 1980; Manurung and Beenackers, 1994; Reed and Markson, 1985), but these works were still based ...
Progress in Computational Fluid Dynamics, An International Journal, 2007
Department of Chemical and Process Engineering, Sheffield University Waste Incineration Centre (S... more Department of Chemical and Process Engineering, Sheffield University Waste Incineration Centre (SUWIC), Sheffield University, Mappin Street, Sheffield, S1 3JD, UK Fax: 0044 -114-2227501 E-mail: ybyang@Sheffield.ac.uk E-mail: vnsharifi@shef.ac.uk E-mail: ...
Process Safety and Environmental Protection, 2005
Process Safety and Environmental Protection, 2000