A comparative optimisation study of activated carbon production from hazelnut shells by thermal and microwave heating methods

This research has studied the optimisation of activated carbon production from waste hazelnut shells, using both conventional and microwave heating techniques. A comparative study was conducted on the results obtained from both production methods to provide information on the characteristics, advantages and disadvantages of each production technique from a physical and chemical perspective. The study of the conventional production method was carried out using a comprehensive two- stage Response Surface Methodology (RSM). The microwave production method was studied using a combination of RSM and the traditional single-factor-at-a-time experimental design. The comparison of the two production methods showed that at a similar degrees of carbon burn- off, much lower pore volume and internal surface area was achieved for the microwave produced samples. The highest BET surface area produced with the conventional production method was 1777 m2/g, obtained from the activation of carbonised char with 0.67 ml/min water for 4 hours at 900°C. This value was nearly 2.5 times larger than the maximum BET surface area achieved from the microwave production method (715 m2/g) (50 min at 1000W). Similar results were also obtained for the aqueous phase adsorption of phenol and methylene blue; 2.2x and 2.3x larger adsorption capacity for thermal sample, respectively. In general, the microwave production method was found to be less effective in the production of highly microporous carbon. While the rate of micropore development with carbon burn-off in microwave heating was much lower than the conventional method, mesopore volume was found to be close and even comparable with that achieved with the conventional method. Considering that the microwave heating resulted in lower energy consumption per unit carbon burn-off, this heating system can be energy efficient in the production of mesoporous adsorbents. The energy efficiency could be of great importance when a two step carbonisation- activation is to be employed, since it could considerably reduce the heating time to the final activation temperature.Open Acces

A comparative optimisation study of activated carbon production from hazelnut shells by thermal and microwave heating methods

This research has studied the optimisation of activated carbon production from waste hazelnut shells, using both conventional and microwave heating techniques. A comparative study was conducted on the results obtained from both production methods to provide information on the characteristics, advantages and disadvantages of each production technique from a physical and chemical perspective. The study of the conventional production method was carried out using a comprehensive two- stage Response Surface Methodology (RSM). The microwave production method was studied using a combination of RSM and the traditional single-factor-at-a-time experimental design. The comparison of the two production methods showed that at a similar degrees of carbon burn- off, much lower pore volume and internal surface area was achieved for the microwave produced samples. The highest BET surface area produced with the conventional production method was 1777 m2/g, obtained from the activation of carbonised char with 0.67 ml/min water for 4 hours at 900°C. This value was nearly 2.5 times larger than the maximum BET surface area achieved from the microwave production method (715 m2/g) (50 min at 1000W). Similar results were also obtained for the aqueous phase adsorption of phenol and methylene blue; 2.2x and 2.3x larger adsorption capacity for thermal sample, respectively. In general, the microwave production method was found to be less effective in the production of highly microporous carbon. While the rate of micropore development with carbon burn-off in microwave heating was much lower than the conventional method, mesopore volume was found to be close and even comparable with that achieved with the conventional method. Considering that the microwave heating resulted in lower energy consumption per unit carbon burn-off, this heating system can be energy efficient in the production of mesoporous adsorbents. The energy efficiency could be of great importance when a two step carbonisation- activation is to be employed, since it could considerably reduce the heating time to the final activation temperature.Open Acces

Industry/University Collaboration at the University of Michigan-Dearborn: A Focus on Relevant Technology

https://deepblue.lib.umich.edu/bitstream/2027.42/154106/1/kampfner1998.pd

Rice straw fiber polymer composites: thermal and mechanical performance

Rice straw fiber can be considered as important potential reinforcing filler for thermoplastic composite because of its lignocellulosic characteristics. It is thus of practical significance to understand and predict the thermal decomposition process of rice straw fibers. A method proposed by Málek, Šesták, and co-workers was used to investigate and model thermal decomposition process of common natural fibers with detailed analysis on rice straw system. Assuming a global model occurring within the entire degradation of natural fibers with consideration of fiber as one pseudo-component, model can be used to describe both isothermal and non-isothermal degradation process of most selected fibers within acceptable error limits of 3 and 5%, respectively. The parameters of kinetic model were given in this dissertation. The model obtained has practical significance for introducing straw fiber into some engineering plastics with comparatively lower melting temperature. Influences of different rice straw components, and compatibilizers on various properties of rice-straw based polymer composites were also investigated. Rice straw fibers can work well with both VHDPE and RHDPE as reinforcing filler. Also, different components of rice straw had no significant influence on mechanical properties of composites. The PE-g-MA/EPR ratio affected mechanical properties of composites modified by combined compatibilizers. The optimum PE-g-MA/EPR ratio was considered to be 2:1 and 1:1 for PE-g-MA/uEPR and PE-g-MA/EPR-g-MA modified composites, respectively. At the optimum ratio, composites modified by combined compatibilizers showed better strength and impact toughness, and acceptable modulus compared to those modified by either EPR or EPR-g-MA. It was found that 13% weight loss seemed to be the limit for rice straw to maintain its strength in a composite system. High-temperature one-step extrusion was feasible for manufacturing HDPE/nylon-6/rice-straw composites without significant strength loss caused by thermal degradation of fiber. The two-step method failed to exhibit better performance than the one-step method

Fission product diffusion in ig-110 graphite

The threat of global climate change and resultant disasters has never been higher. The promises made by many countries of carbon neutrality by 2050 will be impossible to achieve without nuclear technology. Global public support for nuclear energy is at its highest level in modern history but is still severely hampered by perceptions of safety and issues involving nuclear waste and proliferation. The Fukushima disaster of 2011 and the attack on Ukraine by the Russian Federation in 2022 only served to highlight the dangers of older reactor technology and the potential for large releases of radioactivity either by accident or intentional sabotage. For these reasons most countries have a keen interest in improved reactor technologies, particularly in regards to safety, as they plan to build, or continue building, their nuclear fleets. Generation-IV reactors are characterized by improved safety, economics, and proliferation resistance compared to current light water reactor designs. The hightemperature gas-cooled reactor (HTGR) exemplifies these characteristics with the additional benefit of process heat production capabilities. Past and current demonstration reactors have proved the technical feasibility of the design and several future reactors are set to enter demonstration phases as early as the late 2020s. Despite strong performance in past and present reactors, there remains several unknown variables, particularly in regards to fission product behavior and transport under differing reactor conditions. Due to the robust nature of the tristructural isotropic fuel particles used in HTGRs, as well as the large amount of graphite comprising the core, there is little risk of a reactor meltdown. Instead, the primary safety consideration of HTGRs is the release of radioactive materials from the core, either during normal operation or an off-normal event. Most fission and activation products will be completely retained in either the fuel particle or the surrounding matrix graphite; a few, however, have a demonstrated ability to migrate through all core structures and deposit onto cooling system components. This poses a danger to reactor workers and, if the closed coolant circuit were to be compromised, the public. With that in mind, it is essential to fully understand the transport parameters of these select radionuclides in every component of the reactor core, including the core structural graphite. This work has measured effective diffusion coefficients of Sr, Ag, Pd, Eu, and Cs in IG-110 structural graphite. A time-release method was utilized to measure these diffusion coefficients at temperatures up to 1973 K using an inductively-coupled plasma mass spectrometer. The effective diffusion coefficients here reported can be used to aid predictive fission product transport programs.Includes bibliographical references

Modelling and simulation of biomass fast pyrolysis process: Kinetics, reactor, and condenser systems

The research focuses on understanding implementation of multi-scale modeling and simulation of biomass fast pyrolysis process. Lumped and detailed pyrolysis kinetic models are proposed based on experimental and literature data validation. The detailed kinetics is coupled with an engineering model of bubbling fluidized bed reactor to predict pyrolysis gas and bio-oil composition. A simulation strategy to fractionally condense major pyrolysis components into distinct chemical families is proposed using ASPENPlus

Microwave Acoustic SAW Resonators for Stable High-temperature Harsh-Environment Static and Dynamic Strain Sensing Applications

High-temperature, harsh-environment static and dynamic strain sensors are needed for industrial process monitoring and control, fault detection, structural health monitoring in power plant environments, steel and refractory material manufacturing, aerospace, and defense applications. Sensor operation in the aforementioned extreme environments require robust devices capable of sustaining the targeted high temperatures, while maintaining a stable sensor response. Current technologies face challenges regarding device or system size, complexity, operational temperature, or stability. Surface acoustic wave (SAW) sensor technology using high temperature capable piezoelectric substrates and thin film technology has favorable properties such as robustness; miniature size; capability of mass production; reduced installation costs; battery-free operation; maintenance-free; and offer the potential for wireless, multi-sensor interrogation. These characteristics are very attractive for static and dynamic strain sensors targeted to operate in high-temperature harsh-environment conditions. The investigation of harsh-environment static and dynamic SAW strain sensors requires addressing the issues of: (i) sensor platform endurance and stability; (ii) development of durable packaging and attachment techniques; (iii) temperature compensation techniques, to mitigate temperature cross-sensing; and (iv) methods of sensor interrogation and calibration at high temperatures. In this work, langasite-based SAW resonator (SAWR) sensors have been investigated. A stable sensor platform was verified for two types of thin-film electrode configurations, namely: co-deposited Pt/Al2O3 (up to 750oC) and multilayered PtNi|PtZr (up to 1000oC). High-temperature sensor attachment solutions for strain sensor applications were developed for temperatures up to 500oC. The developed SAWR sensors were tested and calibrated for both static and dynamic strain up to 400oC. A temperature compensation technique and a novel finite element analysis was used to perform high-temperature static strain calibration. A high-temperature dynamic strain test rig using a constant stress beam was designed, implemented and used to characterize the SAWR strain sensor performance in measuring dynamic strain. Using the in-phase and quadrature strain sensor signal analysis technique proposed and developed in this study, the existence of both amplitude and frequency modulations of the SAWR RF signal by the dynamic strain signal was confirmed, and the two types of modulations separated and quantified

Framework for operability assessment of production facilities: an application to a primary unit of a crude oil refinery

This work focuses on the development of a methodology for the optimization, control and operability of both existing and new production facilities through an integrated environment of different technologies like process simulation, optimization and control systems. Such an integrated environment not only creates opportunities for op¬erational decision making but also serves as training tool for the novice engineers. It enables them to apply engineering expertise to solve challenges unique to the process industries in a safe and virtual environment and also assist them to get familiarize with the existing control systems and to understand the fundamentals of the plant operation. The model-based methodology proposed in this work, starts with the implementation of first principle models for the process units on consideration. The process model is the core of the methodology. The state of art simulation technologies have been used to model the plant for both steady state and dynamic state conditions. The models are validated against the plant operating data to evaluate the reliability of the models. Then it is followed by rigorously posing a multi-optimization problem. In addition to the basic economic variables such as raw materials and operating costs, the so-called “triple-bottom-line” variables related with sustainable and environmental costs are incorporated into the objective function. The methodologies of Life Cycle Assessment (LCA) and Environmental Damage Assessment (EDA) are applied within the optimization problem. Subsequently the controllability of the plant for the optimum state of conditions is evaluated using the dynamic state simulations. Advanced supervisory control strategies like the Model Predictive Control (MPC) are also implemented above the basic regulatory control. Finally, the methodology is extended further to develop training simulator by integrating the simulation case study to the existing Distributed Control System (DCS). To demonstrate the effectiveness of the proposed methodology, an industrial case study of the primary unit of the crude oil refinery and a laboratory scale packed distillation unit is thoroughly investigated. The presented methodology is a promising approach for the operability study and optimization of production facilities and can be extended further for an intelligent and fully-supportable decision making