Master of Science

thesisA booster fan is an underground ventilation device installed in series with a main surface fan and is used to boost the pressure of air of the current passing through it. Currently, federal regulations in the U.S. do not permit the use of booster fans in underground bituminous and lignite coal mines. Considering that a booster fan is an active device with moving parts, it is imperative to install it with an efficient and reliable monitoring and control system. The important aspects of booster fans and monitoring systems that are discussed in this thesis are environmental monitoring, condition monitoring, design and installation principles, guidelines for safe operation of booster fans, fan interlocking, and risk assessment. The environmental status of underground mining operations with large booster fans is critical to the health and safety of the miners. Mining operations, especially in large deep coal mines, rely greatly upon the monitoring systems to create safe and healthy work conditions by monitoring carbon monoxide, methane, carbon dioxide, oxygen, nitrogen oxides, and smoke. Condition monitoring is the process of measuring the fan operating factors to evaluate and predict the health of mining machinery. In coal mine ventilation, condition monitoring includes the measurement and evaluation of the following factors: vibration, barometric pressure, noise, input power, motor and bearing temperatures, differential pressures, and air flow rate. The monitoring system network in a mine could become extremely complex if the monitors are not located at the right place. Recommendations are given for calculating the appropriate siting and spacing of monitors. Booster fans are assembled and installed to operate under harsh conditions; they are subject to wear and tear and malfunction. Installation principles are discussed in detail and recommendations are made for the safe operation of booster fans. Interlocking is one method of preventing the occurrence of unsafe conditions due to electrical or mechanical failures. It is described in detail, and the best practices used in other coal mining countries are summarized. To ensure the safe operation of booster fans and monitoring systems underground, a risk assessment was done, critical hazards were identified, and mitigation controls are outlined

Design and Development of a Multi-Nodal Methane Detection System for Longwall Coal Mining

Methane (CH4) explosions pose significant dangers in longwall mining that may lead to injuries and fatalities. Safety is improved through diligent monitoring of CH4 concentration. Currently, regulations require a CH4 monitor be placed on the shearer, downwind of the cutting head. Portable monitor measurements must be taken at various times and locations. If any CH4 monitor measures a concentration greater than 1%, a warning signal must be given. Based on previous research and the location of the CH4 monitor mounted on the shearer (closest monitor to the face), if 1% methane is measured, the concentration at the face may be already be at the lower explosive limit (5%). If any monitor measures a concentration greater than 2%, production is halted. However, there are spatial and temporal gaps in measurements where a dangerous CH4-air mixture may develop and go undetected. This poses a risk of shearers or other work activity igniting these dangerous mixtures. Through funding provided by The Alpha Foundation for the Improvement of Mine Safety and Health, Inc., a multi-nodal Methane Watchdog System (MWS) was developed to improve CH4 monitoring by decreasing the spatial and temporal measurement gaps. The prototype consisted of 10 sampling nodes distributed along the longwall. Each node had a sampling location near the face and gob. The nodes were connected in series and communicated with a central processing hub. Each node consisted of a sealed box which housed sensors and other components. Two CH4 sensors (metal-oxide and infrared) were mounted in a custom sampling block with climate sensors. Two tubes transported gas samples from relevant locations to the sampling block at the node. The units could sample continuously, alternating between each location. The MWS nodes were powered by low voltage DC power common among shields. In addition, a custom water powered ejector was designed to provide the motive sampling force and represented a critical system component. The ejector was designed to provide sampling for a single unit at flowrate of 2 SLPM. Pressurized water, already powering spray nozzles, would provide an inherently explosion proof motive energy source for active sampling. Ideally, water consumption should be minimized while maintaining enough suction force to draw the sample through the unit at the desired flowrate. An initial ejector design was 3D printed and tested to access its performance. During experimental testing, the ejector demonstrated two distinct operational curves (“High” and “Low” pressure), between which it was believed a flow regime transition from bubble to jet flow occurred. Based on a significant increase in performance post-transition, it was recommended that the ejector operate on the “Low” pressure curve. However, this mode did not meet the flowrate requirement. Thus, a multi-nozzle design was developed and tested, demonstrating the same flow transition. The multi-nozzle ejector was also modelled using a computational fluid dynamics (CFD) software. Experimental points were used to verify the CFD model to predict that a scaled version of the multi-nozzle design met the flowrate and suction force requirements with reduced water consumption

Reactor Designs for Safe and Intensified Hydrogenations and Oxidations: From Micro- to Membrane Reactors

The current and pressing environmental challenges are leading towards an important paradigm shift within the chemical industry. Green chemistry can be performed by using selective catalysts, and renewable and environment-friendly feedstock. For this reason, it is essential to provide scientists with platform tools that can allow safe and reliable catalyst testing, screening and studies. At the same time, as the use of green feedstock, such as oxygen and hydrogen, can pose new hazards, the design of intensified reactors can represent an unmissable opportunity to drive this green shift within the safe and scalable production of valuable molecules. This thesis reports reactor design solutions of different scale that have been devised to guarantee safe and intensified catalytic hydrogenations and oxidations for catalyst testing and continuous production purposes. Starting with the aim of studying a catalyst under realistic operating conditions, a silicon microfabricated reactor was designed and tested for the gas phase combustion of methane and carbon monoxide over palladium and platinum catalysts. Owing to its small volume and to its isothermal temperature profile, this microreactor proved to be a safe and effective tool for performing information-rich experiments, while exhibiting a plug-flow behaviour with negligible external and internal mass transfer resistances. Reactions were performed in combination with X-ray absorption and IR spectroscopy, allowed by the detailed microfabrication reactor design, to investigate the catalyst structure-activity relationships in steady-state and transient experiments. Boosting the catalyst activity can be achieved using catalytic nanoparticles, which offer an increased surface area compared to their bulk equivalents and hence an improved reaction rate. However, accessibility of the reactants to supported nanoparticles can be limited by the diffusion phenomena occurring around and inside a catalyst support. A recent trend of supporting nanoparticles onto surfaces modified using polyelectrolyte assemblies has attracted attention owing to the low temperature, ease and environmentally friendly preparation process. Finely tuned ex situ synthesised palladium nanoparticles were adsorbed on the inner surface of a tubular Teflon AF-2400 membrane, which was modified with polyelectrolytes in a layer-by-layer configuration. The membrane was used as a tubular reactor inside an outer tube with pressurised hydrogen, and nanoparticles of different size and shape were tested in the continuous hydrogenation of nitrobenzene to aniline. The observed reactivity depended on the different nanoparticle size and on the palladium oxidation state. The use of a tube-in-tube membrane reactor ensured process safety owing to the small volume of gas stored in the tube annular section and to the continuous processing. Alcohol oxidations using molecular oxygen can be dangerous due to the risk of creating explosive mixtures with the organic substrate. Two slurry loop reactors were developed using the same Teflon AF-2400 membrane in different configurations: a tube-in-tube and a flat membrane configuration for scalable reactions. These were designed and tested to carry out safe aerobic oxidation of alcohols. The membrane separated the oxygen from the organic phase and allowed a controlled dosing of the gaseous reactant. In order to boost the turnover frequency, the catalyst was used in the form of a slurry which was recirculated in a loop where it contacted the membrane saturator and a crossflow filter. This allowed the withdrawal of the liquid products from the loop. The reactors could be operated continuously, and provided improved process safety and comparable catalyst turnover frequency to conventional batch processes. When scaling up reactors, inadequate mixing can occur impacting on process safety and product quality. A Taylor-vortex membrane reactor is presented for the first time, combining the benefits of a flexible baffle structure inside a Taylor-vortex system that can hinder axial dispersion, and a supported tubular membrane for safe gas-liquid reactions. Stable conversion and product selectivity were achieved in the homogeneously catalysed continuous aerobic oxidation of benzyl alcohol. No pervaporation of organics through the membrane was detected during reaction, making this reactor a safe and a scalable tool for continuous gas-liquid reactions

Porous Ceramic Sensors: Hydrocarbon Gas Leaks Detection

According to the American National Standards Institute (ANSI), a sensor is a device which provides a usable output in response to a specified measurement of a physical quantity converted into a signal suitable for processing (e.g., optical, electrical, or mechanical signals). On the other hand, porous ceramic materials play an important role as sensor materials, because by selecting a suitable base ceramic material for the intended use and then adjusting their overall porosity, pore size distribution, and pore shape, they can cover different applications such as liquid-gas filters, insulators, catalytic supports, mixed of gases separators and sensors, among others. In addition, they have controlled permeability, high melting point, high superficial area, high corrosion and wear resistance, low expansion coefficient, tailored electronic properties, etc. Currently, a few niche areas demand sensors for compact electronic device design, e.g., leak inspections for oil and gas dispositive, flammable and/or toxic gas detection in waste storage areas and confined spaces, hydrocarbons and their associated gas detection at low temperatures and high humidity conditions, among others. In this chapter, the advances in porous ceramic production for hydrocarbons and associated gas detection will be presented and discussed

Biomass for Energy Country Specific Show Case Studies

In many domestic and industrial processes, vast percentages of primary energy are produced by the combustion of fossil fuels. Apart from diminishing the source of fossil fuels and the increasing risk of higher costs and energy security, the impact on the environment is worsening continually. Renewables are becoming very popular, but are, at present, more expensive than fossil fuels, especially photovoltaics and hydropower. Biomass is one of the most established and common sources of fuel known to mankind, and has been in continuous use for domestic heating and cooking over the years, especially in poorer communities. The use of biomass to produce electricity is interesting and is gaining ground. There are several ways to produce electricity from biomass. Steam and gas turbine technology is well established but requires temperatures in excess of 250 °C to work effectively. The organic Rankine cycle (ORC), where low-boiling-point organic solutions can be used to tailor the appropriate solution, is particularly successful for relatively low temperature heat sources, such as waste heat from coal, gas and biomass burners. Other relatively recent technologies have become more visible, such as the Stirling engine and thermo-electric generators are particularly useful for small power production. However, the uptake of renewables in general, and biomass in particular, is still considered somewhat risky due to the lack of best practice examples to demonstrate how efficient the technology is today. Hence, the call for this Special Issue, focusing on country files, so that different nations’ experiences can be shared and best practices can be published, is warranted. This is realistic, as it seems that some nations have different attitudes to biomass, perhaps due to resource availability, or the technology needed to utilize biomass. Therefore, I suggest that we go forward with this theme, and encourage scientists and engineers who are researching in this field to present case studies related to different countries. I certainly have one case study for the UK to present

Hydrogen, nitrogen and syngas enriched diesel combustion

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel UniversityOn-board hydrogen and syngas production is considered as a transition solution from fossil fuel to hydrogen powered vehicles until problems associated with hydrogen infrastructure, distribution and storage are resolved. A hydrogen- or syngas-rich stream, which substitutes part of the main hydrocarbon fuel, can be produced by supplying diesel fuel in a fuel-reforming reactor, integrated within the exhaust pipe of a diesel engine. The primary aim of this project was to investigate the effects of intake air enrichment with product gas on the performance, combustion and emissions of a diesel engine. The novelty of this study was the utilisation of the dilution effect of the reformate, combined with replacement of part of the hydrocarbon fuel in the engine cylinder by either hydrogen or syngas. The experiments were performed using a fully instrumented, prototype 2.0 litre Ford HSDI diesel engine. The engine was tested in four different operating conditions, representative for light- and medium-duty diesel engines. The product gas was simulated by bottled gases, the composition of which resembled that of typical diesel reformer product gas. In each operating condition, the percentage of the bottled gases and the start of diesel injection were varied in order to find the optimum operating points. The results showed that when the intake air was enriched with hydrogen, smoke and CO emissions decreased at the expense of NOx. Supply of nitrogen-rich combustion air into the engine resulted in a reduction in NOx emissions; nevertheless, this technique had a detrimental effect on smoke and CO emissions. Under low-speed low-load operation, enrichment of the intake air with a mixture of hydrogen and nitrogen led to simultaneous reductions in NOx, smoke and CO emissions. Introduction of a mixture of syngas and nitrogen into the engine resulted in simultaneous reductions in NOx and smoke emissions over a wide range of the engine operating window. Admission of bottled gases into the engine had a negative impact on brake thermal efficiency. Although there are many papers in the literature dealing with the effects of intake air enrichment with separate hydrogen, syngas and nitrogen, no studies were found examining how a mixture composed of hydrogen and nitrogen or syngas and nitrogen would affect a diesel engine. Apart from making a significant contribution to existing knowledge, it is 3 believed that this research work will benefit the development of an engine-reformer system since the product gas is mainly composed of either a mixture of hydrogen and nitrogen or a mixture of syngas and nitrogen.UK Engineering and Physical Science Research Counci

Valorization of Material Wastes for Environmental, Energetic and Biomedical Applications

The development of materials from industrial wastes has attracted the attention of the research community for years. A material's physico-chemical characteristics have specific impacts its properties and their application in environmental, energetic, and biomedical areas, such as in pollutant removal; CO2 capture; energy storage; catalytic oxidation and reduction processes; the conversion of biomass to biofuels; and drug delivery. Examples of such materials are activated carbons, clays, and zeolites, among others. The aim of this Special Issue is to collect the recent advances and progresses developed in this field considering valorised materials from industrial wastes and their applications in environmental, energetic, and biomedical areas

Nanoenergetic Materials

This highly informative and carefully presented book discusses the preparation, processing, characterization and applications of different types of nanoenergetic materials, as well as the tailoring of their properties. It gives an overview of recent advances of outstanding classes of energetic materials applied in the fields of physics, chemistry, aerospace, defense, and materials science, among others. The content of this book is relevant to researchers in academia and industry professionals working on the development of advanced nanoenergetic materials and their applications