There is a trend towards harvesting tidal energy in shallow water. This study examined how tidal ... more There is a trend towards harvesting tidal energy in shallow water. This study examined how tidal energy can be harvested using a device of oscillating cylinders inspired by the roots of mangroves. A specific focus was placed on optimising the configuration of these devices, informed by the computational fluid dynamics (CFD) analysis of wake interference in the von Kármán vortex street of the cylinders. A maximum efficiency of 13.54% was achieved at a peak voltage of 16 mV, corresponding to an electrical power output of 0.0199 mW (13.5% of the hydrokinetic energy of the water) and a power density of 7.2 mW/m2 for a flow velocity of 0.04 m/s (Re=239). The configuration of upstream cylinders proved to have a significant impact on the power generation capacity, corroborated further in CFD simulations. The effect of wake interference was non-trivial on the magnitude and quality of power, with tandem arrangements showing the largest impact followed by staggered arrangements. Though with c...
Ventilation Air Methane (VAM) refers to the release of fugitive methane (CH4) emissions into the ... more Ventilation Air Methane (VAM) refers to the release of fugitive methane (CH4) emissions into the atmosphere during underground coal mining operations. Growing concerns regarding the greenhouse effects of CH4 have led to a worldwide effort in developing efficient and cost-effective methods of capturing CH4. Among these, absorption-based processes, particularly those using Ionic Liquids (ILs) are appealing due to their advantages over conventional methods. In this study, the solubility of CH4 in various ILs, expressed by Henry’s law constant, is first reviewed by examining a wide range of experimental techniques. This is followed by a review of thermodynamic modelling tools such as the extended Henry’s law model, extended Pitzer’s model, Peng–Robinson (PR) equation of state, and Krichevsky−Kasarnovsky (KK) equation of state as well as computational (Artificial Neural Network) modelling approaches. The comprehensive analysis presented in this paper aims to provide a deeper understandin...
Accidental flame initiation to propagation in pipes carrying flammable gases is a significant saf... more Accidental flame initiation to propagation in pipes carrying flammable gases is a significant safety concern that can potentially result in loss of life and substantial damage to property. The understanding of flame propagation characteristics caused by methane–air mixtures within various extractive and associated process industries such as coal mining is critical in developing effective and safe fire prevention and mitigation countermeasures. The aim of this study is to investigate and visualise the fire and explosion properties of a methane–air mixture in a straight pipe with and without obstacles. The experimental setup included modular starting pipes, an array of sensors (flame, temperature, and pressure), a gas injection system, a gas analyser, data acquisition and a control system. The resulting observations indicated that the presence of obstacles within a straight pipe eventuated an increase in flame propagation speed and deflagration overpressure as well as a reduction in t...
Ventilation air methane is low concentration methane (below 1 vol. %) emitted from an underground... more Ventilation air methane is low concentration methane (below 1 vol. %) emitted from an underground coal mine. High ventilation air volumes circulated through the mine, ensure that the methane remains at a safe concentration. In 2016, the Australian Government reported fugitive emissions of methane from underground coal mines at approximately 19.0 million tonnes (CO 2-equivalent) which was about 4.0% of Australia's national greenhouse gas emissions. Therefore, an optimised process of heat recovery from a fluidised-bed VAM abatement reactor, to produce power and cooling was studied. For a ventilation flow rate of 20 m 3 /s, the minimum methane concentration for a direct gas turbine was 0.45 vol. % at a reactor temperature of 630°C and compressor pressure of 1.5 bar. An indirect gas turbine process operated with a minimum methane concentration was 0.4 vol. % at a reactor temperature of 630°C, compressor pressure of 4.0 bar and turbine flow rate of 2.2 kg/s.
Rapid suppression is a must in the mitigation of ventilation air methane (VAM) explosions. Flame ... more Rapid suppression is a must in the mitigation of ventilation air methane (VAM) explosions. Flame suppression proves to be much more challenging than prevention of flame initiation due to the small physics timescale (~1 s). This study numerically investigates the effect of spherical obstructions on flame propagation dynamics in a tube closed at one end. Obstructions with an inflating geometry, installed at different locations, were examined. Noticeably, in the presence of a single or multiple obstructions that partially block the tube, flame and pressure waves propagate faster upstream than in an empty tube; this phenomenon is more pronounced when the obstruction is located further away from the ignition point. In scenarios of a full blockage of the tube, the high pressure builds up inside the blocked region, e.g., surging up to 7.5 bar in less than 0.1 s at a location 10 m away from the ignition point (tube diameter: 0.456 m). Obstructions located closer to the ignition point experi...
The ventilation air–methane (VAM) released from underground mines is often transported into regen... more The ventilation air–methane (VAM) released from underground mines is often transported into regenerative thermal oxidizer (RTO) devices and burnt into heat energy. This study numerically investigates the scenarios where explosion occurs inside the RTO and the flame and pressure waves propagate back quickly towards the VAM discharge duct. Possibilities of secondary explosion in the discharge duct, hence in the downstream underground mines, are examined. The results critically showed that when the methane concentration accumulated in the RTO reached 7.5% or above, the flame generated from the explosion jumped to the evasé of the discharge section (over a distance of 29.4 m) and could induce explosions in underground mines.
2020 10th International Conference on Cloud Computing, Data Science & Engineering (Confluence), 2020
Authenticity is a substantial matter and a current concern of the organic food industry. Organic ... more Authenticity is a substantial matter and a current concern of the organic food industry. Organic foods are appreciated by customers because of their benefits to health and friendliness to the environment. However, currently, the most common way for customers to confirm that the organic food they are buying are organic is by certificates and label information, which can be fraudulent. Furthermore, it is interesting to gain insight into organic food composition and visualize which mineral components are fundamental in the differentiation of organic from conventional food. This work addresses these problems using data mining concepts and techniques in a comparative study of organic and conventional food focusing on grape juice, but the proposed methodology can be adapted and employed for analysis of other types of organic food. This article presents a data mining analysis of the elemental composition of 37 grape juice samples collected from different locations in Brazil. The elemental composition of grape juice samples was determined by inductively-coupled plasma-mass spectrometry (ICP-MS). Forty-four elements were determined in the two types of samples, namely organic and conventional grape juice. Special effort was devoted to selecting the variables (elements) that best described each type of grape juice. Predictive models based on support vector machines, neural networks and decision trees were developed to successfully differentiate organic from conventional grape juice samples. We found that, according to the F-score, Chisquare and Random Forest Importance variable selection measures, the components Na, Sn, P, K, Sm and Nd are among the most important variables in the differentiation of organic and conventional grape juice samples. Particularly, the components Na, Sn and K received first, second or third position according to at least two methods. On the other hand, all variable selection methods considered indicated that Ag, Zn, Cr, Be and Pd were among the least important variables for the differentiation of organic and conventional grape juices. SVM yielded an accuracy of 89.18%, both CART and MLP achieved an accuracy of 86.48%.
Thisarticle provides an understanding on the theoretical modelling of gas explosions. Several com... more Thisarticle provides an understanding on the theoretical modelling of gas explosions. Several commercial software are available; however, it is important to know how they work and their limitations. A theoretical modelling of gas explosion is the integration of several sub-models including chemical reaction, fluid dynamics and thermodynamic models. Once these sub-models are known, it is important to determine how accurate is sufficiently accurate. This understanding determines the level of computational expense required to conduct the targeted theoretical modelling of gas explosions. This article provides the readers an understanding on the requirements in the development of computational modelling of gas explosion.
Heat recovery from a fluidised-bed ventilation air methane abatement reactor and conversion into ... more Heat recovery from a fluidised-bed ventilation air methane abatement reactor and conversion into power using a Rankine cycle based steam turbine and cooling via an absorption chiller was simulated using the process simulation package Aspen Plus. The primary aim of the simulation was to determine the minimum methane concentration for self-sustaining operation, both in terms of maintaining the oxidation process at high temperature and to generate sufficient power to operate the plant. For a ventilation air flow rate of 20 m 3 /s (equivalent to a single abatement module), the minimum methane concentration was found to be 0.46 vol% at a reactor temperature of 650°C and ambient pressure. The Rankine cycle operated with a steam pressure of 7.0 bar and steam flow rate of 0.4 kg/s. At the minimum methane concentration the process was self-sustained with zero net power being produced. The cooling produced at 0.46 vol% was 680 kW R using an indirect-fired absorption chiller while 780 kW R was produced via a direct-fired absorption chiller. Assuming a total ventilation air flow rate of 300 m 3 /s, fifteen 20 m 3 /s modules would be required, producing a total of up to 11,700 kW R of cooling. The net power produced was zero between reactor temperatures of 500 and 700°C at the investigated steam pressures (2.0-7.0 bar). Excess net power was produced at reactor temperatures greater than 700°C due to the restriction of the inlet VAM temperature to 600°C (to prevent auto-ignition of the methane upstream of the reactor). At low reactor temperatures the steam flow rate decreased with both reactor temperature and steam pressure but remained constant at reactor temperatures of 750 and 800°C. The methane abatement plant would be able to operate without an external power supply through the utilisation of the process heat. The plant would produce adequate cooling for a typical gassy underground coal mine in Australia. Such mines are located in the Bowen Basin of Queensland; a region characterised by high virgin rock temperatures with cooling requirements of up to 7000 kW R .
Journal of Loss Prevention in the Process Industries, 2016
Deflagration explosions of coal dust clouds and flammable gases are a major safety concern in coa... more Deflagration explosions of coal dust clouds and flammable gases are a major safety concern in coal mining industry. Accidental fire and explosion caused by coal dust cloud can impose substantial losses and damages to people and properties in underground coal mines. Hybrid mixtures of methane and coal dust have the potential to reduce the minimum activation energy of a combustion reaction. In this study the Minimum Explosion Concentration (MEC), Over Pressure Rise (OPR), deflagration index for gas and dust hybrid mixtures (K st) and explosive region of hybrid fuel mixtures present in Ventilation Air Methane (VAM) were investigated. Experiments were carried out according to the ASTM E1226-12 guideline utilising a 20 L spherical shape apparatus specifically designed for this purpose. Results: obtained from this study have shown that the presence of methane significantly affects explosion characteristics of coal dust clouds. Dilute concentrations of methane, 0.75e1.25%, resulted in coal dust clouds OPR increasing from 0.3 bar to 2.2 bar and boosting the K st value from 10 bar m s À1 to 25 bar m s À1. The explosion characteristics were also affected by the ignitors' energy; for instance, for a coal dust cloud concentration of 50 g m À3 the OPR recorded was 0.09 bar when a 1 kJ chemical ignitor was used, while, 0.75 bar (OPR) was recorded when a 10 kJ chemical ignitor was used. For the first time, new explosion regions were identified for diluted methane-coal dust cloud mixtures when using 1, 5 and 10 kJ ignitors. Finally, the Le-Chatelier mixing rule was modified to predict the lower explosion limit of methane-coal dust cloud hybrid mixtures considering the energy of the ignitors.
Journal of Loss Prevention in the Process Industries, 2016
The fires and explosions caused by flammable hydrocarbon air mixtures are a major safety concern ... more The fires and explosions caused by flammable hydrocarbon air mixtures are a major safety concern in the chemical and processing industries. The thermo-physical and chemical properties of the flammable fuels in a hybrid form appear to have a significant impact on the combustion process. This usually occurs due to substantial changes in the flammability concentration regimes. The aim of this study is to investigate the fire and explosive properties of hybrid fuels in the chemical and process industries. In addition, it examines the impact of the ignition energy and vessel geometry on the magnitude of the pressure rise and flame propagation velocity. The experimental work was conducted on a cylindrically shaped explosion chamber constructed as part of this study at The University of Newcastle, Australia. The chamber was made of mild steel and was 30 m in length and 0.5 in diameter. It included a series of high resolution pressure transducers, a pyrometer, as well as a high speed video camera. Methane and coal dust were used as fuels and chemical igniters with a known energy were used to ignite the fuels. The results obtained from this study showed that both the ignition energy and the diluted combustible fuel dust have significant impacts on the Over Pressure Rise (OPR) in an explosion chamber. The significant findings included that the OPR doubled when 30 g m À3 of coal dust was added to a 6% methane/ air mixture, and it increased by 60% when 10 kJ was used instead of a 1 kJ ignition source. The initial ignition energy was observed to considerably enhance the speed of both the pressure wave and the flame front, where the pressure wave speed doubled when using a 5 kJ instead of a 1 kJ ignition source. However, the pressure wave speed increased by five times when a 10 kJ was used instead of a 1 kJ ignition source. Additionally, the maximum flame front velocity observed for the ignition source with 5 kJ energy was twice the flame front velocity for the 1 kJ ignition source. Finally, it was observed that the time needed for the initial methane ignition was reduced by about 50% when using a 10 kJ instead of a 1 kJ ignition source.
This paper is concerned about a detailed techno-economic assessment of a hypothetical 500 MWe coa... more This paper is concerned about a detailed techno-economic assessment of a hypothetical 500 MWe coal-fired power plant in New South Wales, Australia, for oxy-fuel conversion using integrated chemical looping air separation (ICLAS) technology and cryogenic air separation unit (CASU). The key objectives of this study are to (i) investigate and compare the detailed integration options for oxy-fuel conversion using ICLAS and CASU and (ii) determine the technical merits of the above integration options and the conditions at which the technologies become economically feasible. The study produced scientific evidence that confirms the viability of the CLAS process from both technical and economic points of view under certain conditions. The detailed technical analysis revealed that ICLAS with natural gas integration is energy-efficient compared to CASU running on parasitic load. This is primarily due to the fact that ICLAS needs less auxiliary power compared to CASU. Despite the fact that ICLAS natural gas integrat...
Coal tailings are a waste product of the coal mining process and consist primarily of gangue mine... more Coal tailings are a waste product of the coal mining process and consist primarily of gangue mineral matter and fine coal particles. In this study, coal tailings sourced from two Australian coal mines (Mine A and Mine B) were subjected to a slow pyrolysis process at temperatures of 400−800°C to create char hereafter known as "chailings". Chailings were originally conceptualized based on the concept of biochar and are a novel waste management strategy for coal tailings. Several methods were used to characterize chailings and quantify the effect of different pyrolysis conditions. X-ray diffraction (XRD) and X-ray fluorescence (XRF) techniques identified the primary mineral constituents as silica (i.e., quartz) and aluminosilicates (i.e., kaolinite or illite). Clear morphologic changes were observed via optical and scanning electron microscopy (SEM) for increasing pyrolysis temperature, with evidence of swelling and devolatilization apparent at high temperatures (>600°C). Proximate analyses indicated near complete devolatilization was apparent at 800°C for both mines, with thermogravimetric analysis (TGA) revealing that peak devolatilization occurred at 455°C for Mine A and 467°C for Mine B. A substantial increase in surface area with increasing pyrolysis temperature was observed for Mine A chailings from 2.7 m 2 /g at 400°C to 75.3 m 2 /g at 800°C, because of the presence of microporosity, while Mine B chailings decreased from 2.4 m 2 /g at 400°C to 1.2 m 2 /g at 800°C, which was attributed to macroporosity and aggregation of particles. Properties of high-temperature (>600°C) chailings, namely, surface area, porosity, and pH offer promise for future investigations regarding the application of chailings to soil.
h i g h l i g h t s " Thermodynamic process simulations were carried out in this paper. " Several... more h i g h l i g h t s " Thermodynamic process simulations were carried out in this paper. " Several integration options have been derived for integrating ICLAS with oxy-fuel. " Effect of key operating parameters and heat sourcing options have been examined. " Oxygen concentrations in the product stream have been calculated. " Results indicate that ICLAS can produce O 2 at much lower costs compared to CASU.
This paper summarizes the results of an experimental investigation into sorbent chemical looping ... more This paper summarizes the results of an experimental investigation into sorbent chemical looping gasification (SCLG) of biomass for the production of high-purity hydrogen and in situ capture of the resulting CO 2. The key innovation was the use of concrete and demolition waste (CDW) as the source of CO 2 sorbent. A comprehensive series of thermogravimetric analysis (TGA) experiments was carried out over a range of temperatures between 650 and 900°C and pressures up to 20 atm to benchmark the CO 2 capture efficiency of CDW against conventional lime-based sorbents [e.g., calcined limestone (CL) and hydrated Portland cement (HPC)]. Effects of controlling parameters, such as the Ca/C ratio, steam/carbon (S/C) ratio, steam partial pressure, and total pressure, on the gas yield, gas composition, and CO 2 capture efficiency were thoroughly examined. Experimental results confirmed that CO 2 capture efficiencies as high as 56.4% and high-grade hydrogen production can be achieved when CDW is used as a sorbent. These results combined with the high mechanical strength, durability, and low cost make CDW an attractive sorbent for chemical looping gasification of carbonaceous solid fuels, particularly biomass.
There is a trend towards harvesting tidal energy in shallow water. This study examined how tidal ... more There is a trend towards harvesting tidal energy in shallow water. This study examined how tidal energy can be harvested using a device of oscillating cylinders inspired by the roots of mangroves. A specific focus was placed on optimising the configuration of these devices, informed by the computational fluid dynamics (CFD) analysis of wake interference in the von Kármán vortex street of the cylinders. A maximum efficiency of 13.54% was achieved at a peak voltage of 16 mV, corresponding to an electrical power output of 0.0199 mW (13.5% of the hydrokinetic energy of the water) and a power density of 7.2 mW/m2 for a flow velocity of 0.04 m/s (Re=239). The configuration of upstream cylinders proved to have a significant impact on the power generation capacity, corroborated further in CFD simulations. The effect of wake interference was non-trivial on the magnitude and quality of power, with tandem arrangements showing the largest impact followed by staggered arrangements. Though with c...
Ventilation Air Methane (VAM) refers to the release of fugitive methane (CH4) emissions into the ... more Ventilation Air Methane (VAM) refers to the release of fugitive methane (CH4) emissions into the atmosphere during underground coal mining operations. Growing concerns regarding the greenhouse effects of CH4 have led to a worldwide effort in developing efficient and cost-effective methods of capturing CH4. Among these, absorption-based processes, particularly those using Ionic Liquids (ILs) are appealing due to their advantages over conventional methods. In this study, the solubility of CH4 in various ILs, expressed by Henry’s law constant, is first reviewed by examining a wide range of experimental techniques. This is followed by a review of thermodynamic modelling tools such as the extended Henry’s law model, extended Pitzer’s model, Peng–Robinson (PR) equation of state, and Krichevsky−Kasarnovsky (KK) equation of state as well as computational (Artificial Neural Network) modelling approaches. The comprehensive analysis presented in this paper aims to provide a deeper understandin...
Accidental flame initiation to propagation in pipes carrying flammable gases is a significant saf... more Accidental flame initiation to propagation in pipes carrying flammable gases is a significant safety concern that can potentially result in loss of life and substantial damage to property. The understanding of flame propagation characteristics caused by methane–air mixtures within various extractive and associated process industries such as coal mining is critical in developing effective and safe fire prevention and mitigation countermeasures. The aim of this study is to investigate and visualise the fire and explosion properties of a methane–air mixture in a straight pipe with and without obstacles. The experimental setup included modular starting pipes, an array of sensors (flame, temperature, and pressure), a gas injection system, a gas analyser, data acquisition and a control system. The resulting observations indicated that the presence of obstacles within a straight pipe eventuated an increase in flame propagation speed and deflagration overpressure as well as a reduction in t...
Ventilation air methane is low concentration methane (below 1 vol. %) emitted from an underground... more Ventilation air methane is low concentration methane (below 1 vol. %) emitted from an underground coal mine. High ventilation air volumes circulated through the mine, ensure that the methane remains at a safe concentration. In 2016, the Australian Government reported fugitive emissions of methane from underground coal mines at approximately 19.0 million tonnes (CO 2-equivalent) which was about 4.0% of Australia's national greenhouse gas emissions. Therefore, an optimised process of heat recovery from a fluidised-bed VAM abatement reactor, to produce power and cooling was studied. For a ventilation flow rate of 20 m 3 /s, the minimum methane concentration for a direct gas turbine was 0.45 vol. % at a reactor temperature of 630°C and compressor pressure of 1.5 bar. An indirect gas turbine process operated with a minimum methane concentration was 0.4 vol. % at a reactor temperature of 630°C, compressor pressure of 4.0 bar and turbine flow rate of 2.2 kg/s.
Rapid suppression is a must in the mitigation of ventilation air methane (VAM) explosions. Flame ... more Rapid suppression is a must in the mitigation of ventilation air methane (VAM) explosions. Flame suppression proves to be much more challenging than prevention of flame initiation due to the small physics timescale (~1 s). This study numerically investigates the effect of spherical obstructions on flame propagation dynamics in a tube closed at one end. Obstructions with an inflating geometry, installed at different locations, were examined. Noticeably, in the presence of a single or multiple obstructions that partially block the tube, flame and pressure waves propagate faster upstream than in an empty tube; this phenomenon is more pronounced when the obstruction is located further away from the ignition point. In scenarios of a full blockage of the tube, the high pressure builds up inside the blocked region, e.g., surging up to 7.5 bar in less than 0.1 s at a location 10 m away from the ignition point (tube diameter: 0.456 m). Obstructions located closer to the ignition point experi...
The ventilation air–methane (VAM) released from underground mines is often transported into regen... more The ventilation air–methane (VAM) released from underground mines is often transported into regenerative thermal oxidizer (RTO) devices and burnt into heat energy. This study numerically investigates the scenarios where explosion occurs inside the RTO and the flame and pressure waves propagate back quickly towards the VAM discharge duct. Possibilities of secondary explosion in the discharge duct, hence in the downstream underground mines, are examined. The results critically showed that when the methane concentration accumulated in the RTO reached 7.5% or above, the flame generated from the explosion jumped to the evasé of the discharge section (over a distance of 29.4 m) and could induce explosions in underground mines.
2020 10th International Conference on Cloud Computing, Data Science & Engineering (Confluence), 2020
Authenticity is a substantial matter and a current concern of the organic food industry. Organic ... more Authenticity is a substantial matter and a current concern of the organic food industry. Organic foods are appreciated by customers because of their benefits to health and friendliness to the environment. However, currently, the most common way for customers to confirm that the organic food they are buying are organic is by certificates and label information, which can be fraudulent. Furthermore, it is interesting to gain insight into organic food composition and visualize which mineral components are fundamental in the differentiation of organic from conventional food. This work addresses these problems using data mining concepts and techniques in a comparative study of organic and conventional food focusing on grape juice, but the proposed methodology can be adapted and employed for analysis of other types of organic food. This article presents a data mining analysis of the elemental composition of 37 grape juice samples collected from different locations in Brazil. The elemental composition of grape juice samples was determined by inductively-coupled plasma-mass spectrometry (ICP-MS). Forty-four elements were determined in the two types of samples, namely organic and conventional grape juice. Special effort was devoted to selecting the variables (elements) that best described each type of grape juice. Predictive models based on support vector machines, neural networks and decision trees were developed to successfully differentiate organic from conventional grape juice samples. We found that, according to the F-score, Chisquare and Random Forest Importance variable selection measures, the components Na, Sn, P, K, Sm and Nd are among the most important variables in the differentiation of organic and conventional grape juice samples. Particularly, the components Na, Sn and K received first, second or third position according to at least two methods. On the other hand, all variable selection methods considered indicated that Ag, Zn, Cr, Be and Pd were among the least important variables for the differentiation of organic and conventional grape juices. SVM yielded an accuracy of 89.18%, both CART and MLP achieved an accuracy of 86.48%.
Thisarticle provides an understanding on the theoretical modelling of gas explosions. Several com... more Thisarticle provides an understanding on the theoretical modelling of gas explosions. Several commercial software are available; however, it is important to know how they work and their limitations. A theoretical modelling of gas explosion is the integration of several sub-models including chemical reaction, fluid dynamics and thermodynamic models. Once these sub-models are known, it is important to determine how accurate is sufficiently accurate. This understanding determines the level of computational expense required to conduct the targeted theoretical modelling of gas explosions. This article provides the readers an understanding on the requirements in the development of computational modelling of gas explosion.
Heat recovery from a fluidised-bed ventilation air methane abatement reactor and conversion into ... more Heat recovery from a fluidised-bed ventilation air methane abatement reactor and conversion into power using a Rankine cycle based steam turbine and cooling via an absorption chiller was simulated using the process simulation package Aspen Plus. The primary aim of the simulation was to determine the minimum methane concentration for self-sustaining operation, both in terms of maintaining the oxidation process at high temperature and to generate sufficient power to operate the plant. For a ventilation air flow rate of 20 m 3 /s (equivalent to a single abatement module), the minimum methane concentration was found to be 0.46 vol% at a reactor temperature of 650°C and ambient pressure. The Rankine cycle operated with a steam pressure of 7.0 bar and steam flow rate of 0.4 kg/s. At the minimum methane concentration the process was self-sustained with zero net power being produced. The cooling produced at 0.46 vol% was 680 kW R using an indirect-fired absorption chiller while 780 kW R was produced via a direct-fired absorption chiller. Assuming a total ventilation air flow rate of 300 m 3 /s, fifteen 20 m 3 /s modules would be required, producing a total of up to 11,700 kW R of cooling. The net power produced was zero between reactor temperatures of 500 and 700°C at the investigated steam pressures (2.0-7.0 bar). Excess net power was produced at reactor temperatures greater than 700°C due to the restriction of the inlet VAM temperature to 600°C (to prevent auto-ignition of the methane upstream of the reactor). At low reactor temperatures the steam flow rate decreased with both reactor temperature and steam pressure but remained constant at reactor temperatures of 750 and 800°C. The methane abatement plant would be able to operate without an external power supply through the utilisation of the process heat. The plant would produce adequate cooling for a typical gassy underground coal mine in Australia. Such mines are located in the Bowen Basin of Queensland; a region characterised by high virgin rock temperatures with cooling requirements of up to 7000 kW R .
Journal of Loss Prevention in the Process Industries, 2016
Deflagration explosions of coal dust clouds and flammable gases are a major safety concern in coa... more Deflagration explosions of coal dust clouds and flammable gases are a major safety concern in coal mining industry. Accidental fire and explosion caused by coal dust cloud can impose substantial losses and damages to people and properties in underground coal mines. Hybrid mixtures of methane and coal dust have the potential to reduce the minimum activation energy of a combustion reaction. In this study the Minimum Explosion Concentration (MEC), Over Pressure Rise (OPR), deflagration index for gas and dust hybrid mixtures (K st) and explosive region of hybrid fuel mixtures present in Ventilation Air Methane (VAM) were investigated. Experiments were carried out according to the ASTM E1226-12 guideline utilising a 20 L spherical shape apparatus specifically designed for this purpose. Results: obtained from this study have shown that the presence of methane significantly affects explosion characteristics of coal dust clouds. Dilute concentrations of methane, 0.75e1.25%, resulted in coal dust clouds OPR increasing from 0.3 bar to 2.2 bar and boosting the K st value from 10 bar m s À1 to 25 bar m s À1. The explosion characteristics were also affected by the ignitors' energy; for instance, for a coal dust cloud concentration of 50 g m À3 the OPR recorded was 0.09 bar when a 1 kJ chemical ignitor was used, while, 0.75 bar (OPR) was recorded when a 10 kJ chemical ignitor was used. For the first time, new explosion regions were identified for diluted methane-coal dust cloud mixtures when using 1, 5 and 10 kJ ignitors. Finally, the Le-Chatelier mixing rule was modified to predict the lower explosion limit of methane-coal dust cloud hybrid mixtures considering the energy of the ignitors.
Journal of Loss Prevention in the Process Industries, 2016
The fires and explosions caused by flammable hydrocarbon air mixtures are a major safety concern ... more The fires and explosions caused by flammable hydrocarbon air mixtures are a major safety concern in the chemical and processing industries. The thermo-physical and chemical properties of the flammable fuels in a hybrid form appear to have a significant impact on the combustion process. This usually occurs due to substantial changes in the flammability concentration regimes. The aim of this study is to investigate the fire and explosive properties of hybrid fuels in the chemical and process industries. In addition, it examines the impact of the ignition energy and vessel geometry on the magnitude of the pressure rise and flame propagation velocity. The experimental work was conducted on a cylindrically shaped explosion chamber constructed as part of this study at The University of Newcastle, Australia. The chamber was made of mild steel and was 30 m in length and 0.5 in diameter. It included a series of high resolution pressure transducers, a pyrometer, as well as a high speed video camera. Methane and coal dust were used as fuels and chemical igniters with a known energy were used to ignite the fuels. The results obtained from this study showed that both the ignition energy and the diluted combustible fuel dust have significant impacts on the Over Pressure Rise (OPR) in an explosion chamber. The significant findings included that the OPR doubled when 30 g m À3 of coal dust was added to a 6% methane/ air mixture, and it increased by 60% when 10 kJ was used instead of a 1 kJ ignition source. The initial ignition energy was observed to considerably enhance the speed of both the pressure wave and the flame front, where the pressure wave speed doubled when using a 5 kJ instead of a 1 kJ ignition source. However, the pressure wave speed increased by five times when a 10 kJ was used instead of a 1 kJ ignition source. Additionally, the maximum flame front velocity observed for the ignition source with 5 kJ energy was twice the flame front velocity for the 1 kJ ignition source. Finally, it was observed that the time needed for the initial methane ignition was reduced by about 50% when using a 10 kJ instead of a 1 kJ ignition source.
This paper is concerned about a detailed techno-economic assessment of a hypothetical 500 MWe coa... more This paper is concerned about a detailed techno-economic assessment of a hypothetical 500 MWe coal-fired power plant in New South Wales, Australia, for oxy-fuel conversion using integrated chemical looping air separation (ICLAS) technology and cryogenic air separation unit (CASU). The key objectives of this study are to (i) investigate and compare the detailed integration options for oxy-fuel conversion using ICLAS and CASU and (ii) determine the technical merits of the above integration options and the conditions at which the technologies become economically feasible. The study produced scientific evidence that confirms the viability of the CLAS process from both technical and economic points of view under certain conditions. The detailed technical analysis revealed that ICLAS with natural gas integration is energy-efficient compared to CASU running on parasitic load. This is primarily due to the fact that ICLAS needs less auxiliary power compared to CASU. Despite the fact that ICLAS natural gas integrat...
Coal tailings are a waste product of the coal mining process and consist primarily of gangue mine... more Coal tailings are a waste product of the coal mining process and consist primarily of gangue mineral matter and fine coal particles. In this study, coal tailings sourced from two Australian coal mines (Mine A and Mine B) were subjected to a slow pyrolysis process at temperatures of 400−800°C to create char hereafter known as "chailings". Chailings were originally conceptualized based on the concept of biochar and are a novel waste management strategy for coal tailings. Several methods were used to characterize chailings and quantify the effect of different pyrolysis conditions. X-ray diffraction (XRD) and X-ray fluorescence (XRF) techniques identified the primary mineral constituents as silica (i.e., quartz) and aluminosilicates (i.e., kaolinite or illite). Clear morphologic changes were observed via optical and scanning electron microscopy (SEM) for increasing pyrolysis temperature, with evidence of swelling and devolatilization apparent at high temperatures (>600°C). Proximate analyses indicated near complete devolatilization was apparent at 800°C for both mines, with thermogravimetric analysis (TGA) revealing that peak devolatilization occurred at 455°C for Mine A and 467°C for Mine B. A substantial increase in surface area with increasing pyrolysis temperature was observed for Mine A chailings from 2.7 m 2 /g at 400°C to 75.3 m 2 /g at 800°C, because of the presence of microporosity, while Mine B chailings decreased from 2.4 m 2 /g at 400°C to 1.2 m 2 /g at 800°C, which was attributed to macroporosity and aggregation of particles. Properties of high-temperature (>600°C) chailings, namely, surface area, porosity, and pH offer promise for future investigations regarding the application of chailings to soil.
h i g h l i g h t s " Thermodynamic process simulations were carried out in this paper. " Several... more h i g h l i g h t s " Thermodynamic process simulations were carried out in this paper. " Several integration options have been derived for integrating ICLAS with oxy-fuel. " Effect of key operating parameters and heat sourcing options have been examined. " Oxygen concentrations in the product stream have been calculated. " Results indicate that ICLAS can produce O 2 at much lower costs compared to CASU.
This paper summarizes the results of an experimental investigation into sorbent chemical looping ... more This paper summarizes the results of an experimental investigation into sorbent chemical looping gasification (SCLG) of biomass for the production of high-purity hydrogen and in situ capture of the resulting CO 2. The key innovation was the use of concrete and demolition waste (CDW) as the source of CO 2 sorbent. A comprehensive series of thermogravimetric analysis (TGA) experiments was carried out over a range of temperatures between 650 and 900°C and pressures up to 20 atm to benchmark the CO 2 capture efficiency of CDW against conventional lime-based sorbents [e.g., calcined limestone (CL) and hydrated Portland cement (HPC)]. Effects of controlling parameters, such as the Ca/C ratio, steam/carbon (S/C) ratio, steam partial pressure, and total pressure, on the gas yield, gas composition, and CO 2 capture efficiency were thoroughly examined. Experimental results confirmed that CO 2 capture efficiencies as high as 56.4% and high-grade hydrogen production can be achieved when CDW is used as a sorbent. These results combined with the high mechanical strength, durability, and low cost make CDW an attractive sorbent for chemical looping gasification of carbonaceous solid fuels, particularly biomass.
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Papers by Jafar Zanganeh