Work in Progress: Flexibility and Professional Preparation via a Multidisciplinary Engineering Curriculum

This paper reports on one institution’s work-in-progress to build innovation and creativity into a flexible, ABET accredited undergraduate Engineering B.S. degree that provides a variety of choices to undergraduate engineering students. The new Engineering Plus degree has a core set of required foundational courses in engineering, a multi-year design sequence, and allows for self-defined pathways. The new curriculum also offers three defined degree pathways that have been chosen based on an examination of student “fate” data: secondary education, pre-medical, and environmental studies, with additional pathways planned for the near future. The fate analysis examined the paths of students who were enrolled in an engineering or STEM major in one year and samples their major choice in the following year. This analysis maps the flow of students into and out of the major with demographic slicers to more closely understand these inmigration and out-migration choices. This paper will detail the development of the program and its related research inquiry which includes a qualitative comparison of the students who are drawn to this new approach to engineering

Fundamentals of Mercury Oxidation in Flue Gas

The objective of this project is to understand the importance of and the contribution of gas-phase and solid-phase coal constituents in the mercury oxidation reactions. The project involves both experimental and modeling efforts. The team is comprised of the University of Utah, Reaction Engineering International, and the University of Connecticut. The objective is to determine the experimental parameters of importance in the homogeneous and heterogeneous oxidation reactions; validate models; and, improve existing models. Parameters to be studied include HCl, NO{sub x}, and SO{sub 2} concentrations, ash constituents, and temperature. This report summarizes Year 3 results for the experimental and modeling tasks. Experiments have been completed on the effects of chlorine. However, the experiments with sulfur dioxide and NO, in the presence of water, suggest that the wet-chemistry analysis system, namely the impingers, is possibly giving erroneous results. Future work will investigate this further and determine the role of reactions in the impingers on the oxidation results. The solid-phase experiments have not been completed and it is anticipated that only preliminary work will be accomplished during this study

Chemical Looping with Oxygen Uncoupling (CLOU) Studies at the University of Utah

Chemical-looping with oxygen uncoupling (CLOU) is one of the emergent fuel combustion technologies being currently investigated which has the potential to assist with CO2 capture from coal-fired power plants. CLOU involves the combustion of fuel in the presence of gaseous-phase oxygen released from the decomposition of an "oxygen carrier" (OC) metal oxide (e.g. CuO). Compared to Chemical-looping Combustion (CLC), the CLOU process has the promise of reducing the fuel reactor volume and the OC inventory.. The CLC process requires slower pre-gasification reaction of the solid fuel into synthesis gas, which is eventually oxidized by the circulating oxygen carrier. The presentation discusses components of the program at the University of Utah including laboratory-scale fluidized bed experiments, process modelling, and construction of a new 100-200 kW process development unit (PDU). The goal of the laboratory-scale experiments is to derive kinetics for the reduction and oxidation of the OCs. The process model is being used to explore material and energy balance scenarios. These scenarios are looking at the amount of OC circulated and, given the kinetics, OC inventories needed. The process model also shows potential heat recovery. Finally, the PDU design considerations are discussed and updates on the construction given

Fundamentals of Hazardous Solid Waste Incineration in a Rotary Kiln Environment

With landfill costs increasing and regulations on landfilling becoming more stringent, alternatives to conventional hazardous waste treatment strategies are becoming more desirable. Incineration is presently a pennanent, proven solution for the disposal of most organic contaminants, but also a costly one, especially in the case of solids which require some auxiliary fuel. The goal of this research is to develop an understanding of the phenomena associated with the evolution of contaminants from solids in the primary combustor of an incineration system. A three fold approach has been used. First, a bench-scale Particle Characterization Reactor was developed to study the transport phenomena on a particle basis, where the controlling processes are mainly intrapanicle. Second, a Bed Characterization Reactor was built to examine the controlling transport phenomena within a bed of panicles, where the processes are primarily interparticle. The results of these studies can be applied to any primary combustor. Finally a pilot-scale rotary kiln was developed to study the evolution of contaminants from solids within a realistic temperature and rotation environment. This paper describes results obtained in a study using a commercial sorbent contaminated with toluene. The data are from the Particle Characterization Reactor and the Rotary-Kiln Simulator. The results show that the method of contamination and charge size do not have a large effect on desorption, while temperature and contaminant concentration are imponant parameters in the evolution of contaminants in a rotary kiln. Preliminary modeling efforts for the kiln are also discussed

Effects of Fuel Components and Combustion Particle Physicochemical Properties on Toxicological Responses of Lung Cells

The physicochemical properties of combustion particles that promote lung toxicity are not fully understood, hindered by the fact that combustion particles vary based on the fuel and combustion conditions. Real-world combustion-particle properties also continually change as new fuels are implemented, engines age, and engine technologies evolve. This work used laboratory-generated particles produced under controlled combustion conditions in an effort to understand the relationship between different particle properties and the activation of established toxicological outcomes in human lung cells (H441 and THP-1). Particles were generated from controlled combustion of two simple biofuel/diesel surrogates (methyl decanoate and dodecane/biofuel-blended diesel (BD), and butanol and dodecane/alcohol-blended diesel (AD)) and compared to a widely studied reference diesel (RD) particle (NIST SRM2975/RD). BD, AD, and RD particles exhibited differences in size, surface area, extractable chemical mass, and the content of individual polycyclic aromatic hydrocarbons (PAHs). Some of these differences were directly associated with different effects on biological responses. BD particles had the greatest surface area, amount of extractable material, and oxidizing potential. These particles and extracts induced cytochrome P450 1A1 and 1B1 enzyme mRNA in lung cells. AD particles and extracts had the greatest total PAH content and also caused CYP1A1 and 1B1 mRNA induction. The RD extract contained the highest relative concentration of 2-ring PAHs and stimulated the greatest level of interleukin-8 (IL-8) and tumor necrosis factor-alpha (TNFα) cytokine secretion. Finally, AD and RD were more potent activators of TRPA1 than BD, and while neither the TRPA1 antagonist HC-030031 nor the antioxidant N-acetylcysteine (NAC) affected CYP1A1 or 1B1 mRNA induction, both inhibitors reduced IL-8 secretion and mRNA induction. These results highlight that differences in fuel and combustion conditions affect the physicochemical properties of particles, and these differences, in turn, affect commonly studied biological/toxicological responses

Ash Particulate Formation from Pulverized Coal under Oxy-Fuel Combustion Conditions

Aerosol particulates are generated by coal combustion. The amount and properties of aerosol particulates, specifically size distribution and composition, can be affected by combustion conditions. Understanding the formation of these particles is important for predicting emissions and understanding potential deposition. Oxy-fuel combustion conditions utilize an oxygen-enriched gas environment with CO₂. The high concentration of CO₂ is a result of recycle flue gas which is used to maintain temperature. A hypothesis is that high CO₂ concentration reduces the vaporization of refractory oxides from combustion. A high-temperature drop-tube furnace was used under different oxygen concentrations and CO₂ versus N₂ to study the effects of furnace temperature, coal type, and gas phase conditions on particulate formation. A scanning mobility particle sizer (SMPS) and aerodynamic particle sizer (APS) were utilized for particle size distributions ranging from 14.3 nm to 20 μm. In addition, particles were collected on a Berner low pressure impactor (BLPI) for elemental analysis using scanning electron microscopy and energy dispersive spectroscopy. Three particle size modes were seen: ultrafine (below 0.1 μm), fine (0.1 to 1.0 μm), and coarse (above 1 μm). Ultrafine mass concentrations were directly related to estimated particle temperature, increasing with increasing temperature. For high silicon and calcium coals, Utah Skyline and PRB, there was a secondary effect due to CO₂ and the hypothesized reaction. Illinois #6, a high sulfur coal, had the highest amount of ultrafine mass and most of the sulfur was concentrated in the ultrafine and fine modes. Fine and coarse mode mass concentrations did not show a temperature or CO₂ relationship. (The table of contents graphic and abstract graphic are adapted from ref 27.

A Simulation-Based Parametric Study of CLOU Chemical Looping Reactor Performance

Chemical looping with oxygen uncoupling (CLOU) is a variant on chemical looping combustion in which the oxygen carrier releases gaseous O2 in the fuel reactor, making it well-suited for solid fuels, since the released gaseous O2 readily reacts with solid char. This study presents several computational fluid dynamic (CFD) simulations of copper-based CLOU in a dual fluidized bed system, each with different operating conditions. The modeling predicted that coal particle sizes as large as 1000 μm did not significantly affect performance. Increased oxygen carrier copper loading resulted in an excess of gaseous oxygen in the product gas stream. Decreasing the oxygen carrier bed mass as well as reducing the air reactor fluidizing velocity did not supply enough oxygen to the fuel reactor to complete combustion of the coal. This generated a failure state in which the temperature continued to decrease in the fuel reactor from the lack of combustion, which in turn reduced the O2 equilibrium partial pressure, further lowering the amount of combustion possible. Sufficient O2 can be maintained in the fuel reactor by ensuring a high enough air reactor velocity and a large enough supply of oxygen carrier inventory to handle the chosen coal feed rate

Design of a Gas-Solid-Solid Separator to Remove Ash from Circulating Fluidized Bed Reactors

Cyclones are one of the most common types of gas-solid separators used in circulating fluidized bed boilers. However, cyclones typically do not allow ash to leave the system through the cyclone exit, causing ash to build up in the fluidized bed and necessitating additional systems to remove ash that builds up in the bed. In this study, an alternative “disengager” gas-solid separator is proposed as a way of inherently separating small and large solids, resulting in a gas-solid-solid separation system where ash is allowed to leave the system along with gas while the desired fluidized bed material is retained. Unlike cyclones, which rely on centrifugal force to separate solids and gas, the disengager separates based on entrainment velocity of the particles. Upwards-flowing gas and particles strike a deflection plate and enter the disengaging chamber where particles with low terminal velocity such as ash fines flow with the gas, while larger particles such as sand fall to the bottom of the separator and are returned to the fluidized bed. In this study, several different proposed disengager configurations are simulated and compared to a typical cyclone using computational fluid dynamic (CFD) simulations. It was found that separation efficiency in the disengager is strongly influenced by the size of the deflection plate, rather than by the size of the unit itself. The predicted separation efficiency showed that compared to a cyclone, the disengager design allows significantly more ash to exit the system but retains a similar amount of desirable material. Additionally, the disengager was predicted to not suffer significantly more erosion that a cyclone

Fundamentals of Mercury Oxidation in Flue Gas Annual Report

The objective of this project is to understand the importance of and the contribution of gas-phase and solid-phase coal constituents in the mercury oxidation reactions. The project involves two experimental scales and a modeling effort. The team is comprised of University of Utah, Reaction Engineering International, and University of Connecticut. The objective is to determine the experimental parameters of importance in the homogeneous and heterogeneous oxidation reactions; validate models; and, improve existing models. Parameters to be studies include HCl, NOx, and SO{sub 2} concentrations, ash constituents, and temperature. This report summarizes Year 1 results for the experimental and modeling tasks. Experiments in the drop tube are just beginning and a new, speciated mercury analyzer is up and running. A preliminary assessment has been made for the drop tube experiments using the existing model of gas-phase kinetics