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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Feasibility for Use of a Seabed Gallery Intake for the Shuqaiq-II SWRO Facility, Saudi Arabia

Mantilla Calderon, David 04 1900 (has links)
Shuqaiq-II IWP is a combined RO water desalination and power plant facility. It operates with an open intake that feeds the plant with 100,000 m3/h of raw water. The facility is located 140 km north of Jizan, in a small bay where the run-off discharges of two wadis converge. The run-off coming from the wadis are rich in alluvial sediments that dramatically decrease the raw water quality at the intake point, causing periodic shutdowns of the plant and increasing the operational cost due to membrane replacement. Subsurface water intakes are an alternative for improving raw water quality, as they provide natural filtering of the feed water as it flows through the systems. In this type of system water flow through the sediment matrix is induced and during the percolation, several physical, chemical and biological processes take place, cleaning the water from particulate matter, resulting in high quality feed water that can be directly sent to the RO process without any additional pretreatment. A full hydrogeological profile of the seabed needs to be performed in order to determine the applicability of one of these systems in each particular location. In this study, 1 km of beach area at Shuqaiq-II IWP was surveyed. Ninety-one (91) samples from the shore and offshore sediments were collected and analyzed for hydraulic conductivity, porosity and grain size distribution. The laboratory analysis showed that the construction of the seabed galleries was technically feasible, and the proposed intake system was design to meet the feed water requirements for the RO facility (530.000 m3/d). The preliminary design consists of 17 cells in total, 16 of which will be in constant operation, and 1 alternate for whenever maintenance is needed in one of the other cells. The seabed gallery design includes 5 layers of sands with a total depth of 5 m. A detailed underdrain design methodology is presented. The system would be operated at an infiltration rate of 10 m/d and an average hydraulic retention time of 7h. Each cell will have an area of 3.500 m2 that will supply 35.000 m3/d of feed water to each RO train.
42

High-efficiency chrome tanning using pre-treatments

Zhang, Yi, Buchanan, Jenna K., Holmes, Geoff, Prabakara, Sujay 26 June 2019 (has links)
Content: Pre-treatments are widely used during tanning processes as to improve the performance of the main tannage. Synchrotron small-angle X-ray scattering (SAXS) and differential scanning calorimetry (DSC) were used to study four common types of pre-treatments, viz. monodentate complexing agent (sodium formate, SF), chelating agent (disodium phthalate, DSP), covalent cross-linker (glutaraldehyde, GA) and nanoclay (sodium montmorillonite, MMT) about their effects on chromium-collagen cross-linking reaction during tanning. Based on the results, the performance of chromium-collagen cross-linking with and without pre-treatments was presented considering five aspects: cross-linking, the level of hydration, hydrothermal stability, uniformity through leather cross-section and the uptake of chrome. Comparing to the original ThruBlu chrome tanning, at the same chrome offers, leather pre-treated using SF, DSP and MMT showed improved hydrothermal stability, uniformity and the level of hydration, while GA showed decreased hydration. All of the pre-treatments reduce surface fixation by decreasing the reactivity of chromium with collagen. Changes in the reaction performance can influence the properties of the leather products as well as the efficiency of the leather manufacturing processes. Insights into the structural changes of collagen during tanning with varied reaction conditions can guide the design of novel, benign tanning processes to reduce environmental impact. Take-Away: 1. Uniformity of the hydrothermal stability through leather cross-section were improved by all of the studied pre-treatments. 2. Reactivity of chromium to cross-link with collagen was reduced as a result of the complexing, covalent cross-linking, or preferential adsorption. 3. Complexing agents and nanoclay pre-treatments tend to retain collagen bound water, while covalent cross-linker causing decrease in the level of hydration of collagen.
43

Evaluation of Cellruptor pre-treatment on biogas yield from various substrates

Thiruvenkadam, Selvakumar January 2011 (has links)
In this thesis work, Cellruptor pre-treatment was evaluated in order to increase biogas yield. Initially, the effects of residence time (30, 60, 90, 120 and 180 min) and substrate release (rapid/non-rapid) from the draining port of Cellruptor on biosludges were investigated to find the optimum operating conditions of Cellruptor. Under these optimum operating conditions, the effect of Cellruptor pre-treatment on batch reactors of various substrates and semi-continuous digester of biosludge were investigated at mesophil biosludge, dewatered sludge, digested sludge, fibre sludge, hay, maize silage, minced meat, orange peel, seaweed and yeast. From the initial study, 90 min residence time and rapid release of pre-treated substrate from draining port were found to be optimum operating conditions of Cellruptor. From the batch experiments, Cellruptor pretreatment showed maximum and minimum increase of methane yield in hay (32%) and dewatered sludge (2%) respectively. The semi-continuous digester experimental results showed increase in biogas production by 22.4% from Cellruptor pre-treatment of biosludge at HRT of 15 days and OLR of 2.0 g VS/L/day. With further studies, Cellruptor pre-treatment may be deployed in large-scale biogas plants to improve biogas yield.
44

Overcoming the Recalcitrance for the Conversion of Kenaf Pulp to Glucose via Microwave-Assisted Pre Treatment Processes

Ooi, Beng Guat, Rambo, Ashley L., Hurtado, Miguel A. 01 March 2011 (has links)
This study evaluates the pre-treatment of cellulose from kenaf plant to yield sugar precursors for the production of ethanol or butanol for use as biofuel additives. In order to convert the crystalline cellulosic form to the amorphous form that can undergo enzymatic hydrolysis of the glycosidic bond to yield sugars, kenaf pulp samples were subjected to two different pre-treatment processes. In the acid pre-treatment, the pulp samples were treated with 37.5% hydrochloric acid in the presence of FeCl 3 at 50 °C or 90 °C whereas in the alkaline method, the pulp samples were treated with 25% sodium hydroxide at room temperature and with 2% or 5% sodium hydroxide at 50 °C. Microwave-assisted NaOH-treatment of the cellulose was also investigated and demonstrated to be capable of producing high glucose yield without adverse environmental impact by circumventing the use of large amounts of concentrated acids i.e., 83-85% phosphoric acid employed in most digestion processes. The treated samples were digested with the cellulase enzyme from Trichoderma reesei. The amount of glucose produced was quantified using the QuantichromTMglucose bioassay for assessing the efficiency of glucose production for each of the treatment processes. The microwave-assisted alkaline pre-treatment processes conducted at 50 °C were found to be the most effective in the conversion of the crystalline cellulose to the amorphous form based on the significantly higher yields of sugar produced by enzymatic hydrolysis compared to the untreated sample.
45

Provozování dešťových vpustí / Operation of rain gutters

Chotová, Tereza January 2022 (has links)
The diploma thesis is divided into two parts. The first theoretical part focuses on rain gutters, their distribution, operation and cleaning. The pollution, pre-treatment of rainwater and rainwater management are alco described here. The second practical part includes testing of selected street rain gutters in the institute of municipal water management laboratories (VHO). Furthermore, these rain gutters are compared and evaluated according to these criteria: filter construction, amount of captured material and cleaning system.
46

Digestão anaeróbia de resíduo de caixa de gordura de laticínio e bagaço de cana de açúcar pré-tratado com CO2 sub e supercrítico / Anaerobic digestion of dairy grease trap residue and sugarcane bagasse pre-treated with sub and supercritical CO2

Rosero Henao, Jenny Carolina 07 June 2017 (has links)
A indústria de laticínios no Brasil gerou no 2014 em torno de 88,5 bilhões de litros de efluente, o resíduo gorduroso (RG) separado no tratamento deste efluente, atualmente carece de tratamento. A digestão anaeróbia (DA) é uma opção de tratamento a partir da qual é possível, entre outras coisas, obter biogás, fonte renovável de energia, que representa uma importante alternativa para compor a matriz energética do país. No entanto, resíduos lipídicos, além de gerar lodos de difícil manejo, descompõem-se em ácidos graxos de cadeia longa (AGCL) que inibem os microrganismos metanogênicos. Como estratégia para tratar efetivamente este resíduo, avaliou se um sistema de co-digestão anaeróbia empregando RG advindo da caixa de gordura de um laticínio, e, bagaço de cana de açúcar (BCA) pré-tratado em condições sub e supercríticas de CO2: (i) 40°C / 70 bar (ii) 60°C / 200 bar e (iii) 80°C / 200 bar, com e sem adição de NaOH, respectivamente. Dos pré-tratamentos avaliados, destaca-se o pré-tratamento com CO2 a 60°C e 200bar pelo qual foi possível remover 8,07% de lignina. A produção metanogênica advinda da digestão anaeróbia de bagaço de cana de açúcar foi aumentada em todos os casos nos quais o material foi pré-tratado com CO2 sub e supercrítico, com exceção do caso no qual se utilizou elevada temperatura e NaOH como modificador de polaridade. Os resíduos advindos da caixa de gordura apresentaram elevado potencial metanogênico na faixa de concentração de substrato estudada, sem que nenhuma inibição fosse verificada. A co-digestão de resíduos gordurosos e bagaço de cana, pré-tratados ou não, não apresentou vantagem com relação à mono-digestão dos materiais. / The dairy industry in Brazil generated in 2014 around 88.5 billion litters of effluent, the fatty residue, separated in the treatment of this effluent, currently lacks treatment. Anaerobic digestion is a treatment option from which it is possible, among other things, to obtain biogas, a renewable source of energy, which represents an important alternative to fix the country\'s energy matrix. However, lipid residues form sludges that are difficult to manage and decompose into long chain fatty acids (LCFAs) that are inhibitory to methanogenic microorganisms. As a strategy to effectively treat this residue, we evaluated an anaerobic co-digestion system employing fatty residues from a fat box of a dairy plant, and sugarcane bagasse pre-treated under sub and supercritical CO2 conditions: (i) 40°C / 70 bar (ii) 60°C / 200 bar and (iii) 80°C / 200 bar, with and without addition of NaOH respectively. Of this pre-treatments, stood out the one with CO2 at 60°C and 200 bar by which was achieved the removal of 8.07% of lignin. The methanogenic production from the anaerobic digestion of sugarcane bagasse was increased in all cases in which the material was pre-treated with sub and supercritical CO2, with the exception to the cases in which high temperatures and NaOH were combined. The residues from the dairy fat box showed high methanogenic potential in the concentration range evaluated and no inhibition was verified. The co-digestion of the greasy residues and the sugarcane bagasse with and without pre-treatment, did not present advantage in compare to the mono-digestion of the materials.
47

Novas perspectivas para uma biorrefinaria de cana-de-açúcar no Brasil / New perspectives for a sugarcane biorefinery in Brazil

Novo, Lísias Pereira 10 June 2016 (has links)
Nas últimas décadas observou-se tanto o crescimento das preocupações ambientais e de sustentabilidade. Neste contexto, surgiu o conceito de biorrefinaria. No Brasil, uma das principais lavouras agroindustriais é a produção de cana-de-açúcar. A indústria sucroalcooleira já atua como um modelo de biorrefinaria tendo a possibilidade de produção de açúcar de etanol e ainda de energia elétrica. Contudo, existe grande potencialidade de produtos de originários de biomassa vegetal. Alguns exemplos das potencialidades são: (i) a utilização dos açúcares da fração polissacarídica para produção de etanol; (ii) produção de polpa e papel; (iii) produção de nanomateriais entre outras. Assim, este trabalho se propõe a buscar e aplicar tecnologias e processos voltados a utilização da cana-de-açúcar para a obtenção de produtos variados. O primeiro processo utilizado é a separação das frações casca e miolo da cana-de-açúcar: na casca existe uma baixa quantidade de células de armazenamento de açúcar e uma maior proporção de fibras estruturais ademais, da epiderme extrai-se a cera; na fração miolo concentra-se a maior parte do caldo rico em sacarose, pela elevada quantidade de células de parênquima. Visando elevar a concentração de sacarídeos para a produção de etanol estudou-se a realização de um processo hidrotérmico usando o próprio suco da cana-de-açúcar para a extração de açúcares da fração de hemiceluloses. Observou-se que para a reação hidrotérmica em meio neutro na faixa de temperaturas estudada (110 a 130°C) cerca de 95% dos sacarídeos são conservados. Contudo, nestas condições reacionais a preservação de massa de hemiceluloses também se mantém nesta faixa, assim verificou-se que o uso de um catalizador ácido permitiria uma conservação de sacarídeos similar e aceleraria a reação de remoção de hemiceluloses. Usando processos similares aos usados na indústria de papel e celulose obteve-se dois materiais celulósicos das frações casca e miolo de cana-de-açúcar com características físico-mecânicas diferenciadas. Apesar do maior teor de células de parênquima no miolo original, observou-se que o papel desta fração apresentou resultados promissores com propriedades similares ao de papeis comerciais. A partir destas polpas, obteve-se dois materiais celulósicos nanofibrilados distintos, sendo o material da casca dúctil e o de miolo mais rígido (maior módulo de Young) e ao mesmo tempo mais frágil (menor alongamento para a ruptura). Verificou-se ainda que a partir dessas polpas celulósicas pode-se produzir nanocristais de celulose II usando um processo de hidrólise e solubilização com ácido sulfúrico seguido de reprecipitação. Desenvolveu-se o processo de produção de nanocristais de celulose I usando água subcrítica associado ou não a CO2. Este processo tem o potencial de substituir a atual produção de nanocristais de celulose visto que neste utiliza-se somente água (com ou sem CO2) para promover a hidrólise em oposição ao método clássico que usa elevadas concentrações de ácido sulfúrico permitindo uma economia financeira e produzindo menor volume de resíduos. / In the last decades environmental concerns and sustainability have grown. In this context, the biorefinery concept arose. In Brazil, one of the leading agro-industrial crops is the production of sugarcane. The sugar industry is already a model of a biorefinery because of the possibility of producing ethanol, sugar and even electricity. However, plant biomass still has a great potential to produce new materials and chemicals. Some of the capabilities are: (i) the use of the sugars from the polysaccharide fraction aiming the ethanol production; (ii) the production of pulp and paper; (iii) production of nanomaterials, among others. This work aims to seek and apply technologies and processes to obtain different products from sugarcane. The first used is the separation of the rind and core fractions of sugarcane: in the rind there is a low amount of sugar storage cells and a higher proportion of structural fibers, and also wax from the epidermis; the core fraction concentrates the majority of the sucrose rich broth as consequence of the high quantity of parenchyma cells. In order to increase the concentration of saccharides a hydrothermal process was studied using the own juice of sugar cane to extract sugars from the hemicellulose fraction. It was observed that for the hydrothermal reaction in neutral medium in the temperature range studied (110 to 130 °C) of about 95% saccharides are conserved. However, in these reaction conditions the hemicellulose preservation is also kept in this range, so it was found that the use of an acid catalyst allow similar saccharides recovery and accelerate the hemicellulose removal. Using similar procedures to those of the pulp and paper industry two cellulosic materials with differentiated physical and mechanical characteristics were obtained from the rind and core fractions of sugarcane. Although most parenchyma content in the original core material, it was observed that this fraction showed promising results with properties similar to commercial papers. From these pulps, two different nanofibrillated cellulosic materials were obtained, being the rind material a ductile material and the core a rigid (higher Young\'s modulus) and brittle (lower elongation at break) one. It was also found that from these pulps cellulose II nanocrystals can be produced using a process of hydrolysis and solubilization with sulfuric acid followed by a reprecipitation process. The production of cellulose I nanocrystals through processes using subcritical water with or without CO2 were developed. These processes have the potential to replace the current nanocrystals production since only water is used (with or without CO2) to promote the hydrolysis, compared to the traditional method, which uses high concentrations of sulfuric acid, thus enabling economical saves and producing less amount of wastes.
48

Dynamic Liquefied Natural Gas (LNG) Processing with Energy Storage Applications

Fazlollahi, Farhad 01 June 2016 (has links)
The cryogenic carbon capture™ (CCC) process provides energy- and cost-efficient carbon capture and can be configured to provide an energy storage system using an open-loop natural gas (NG) refrigeration system, which is called energy storing cryogenic carbon capture (CCC-ES™). This investigation focuses on the transient operation and especially on the dynamic response of this energy storage system and explores its efficiency, effectiveness, design, and operation. This investigation included four tasks.The first task explores the steady-state design of four different natural gas liquefaction processes simulated by Aspen HYSYS. These processes differ from traditional LNG process in that the CCC process vaporizes the LNG and the cold vapors return through the LNG heat exchangers, exchanging sensible heat with the incoming flows. The comparisons include costs and energy performance with individually optimized processes, each operating at three operating conditions: energy storage, energy recovery, and balanced operation. The second task examines steady-state and transient models and optimization of natural gas liquefaction using Aspen HYSYS. Steady-state exergy and heat exchanger efficiency analyses characterize the performance of several potential systems. Transient analyses of the optimal steady-state model produced most of the results discussed here. The third task explores transient Aspen HYSYS modeling and optimization of two natural gas liquefaction processes and identifies the rate-limiting process components during load variations. Novel flowrate variations included in this investigation drive transient responses of all units, especially compressors and heat exchangers. Model-predictive controls (MPC) effectively manages such heat exchangers and compares favorably with results using traditional controls. The last task shows how an unprocessed natural gas (NG) pretreatment system can remove more than 90% of the CO2 from NG with CCC technology using Aspen Plus simulations and experimental data. This task shows how CCC-based technology can treat NG streams to prepare them for LNG use. Data from an experimental bench-scale apparatus verify simulation results. Simulated results on carbon (CO2) capture qualitatively and quantitatively agree with experimental results as a function of feedstock properties.
49

Mechanical and chemical chip pre-treatment in mechanical pulp production

Sjölin, Malin January 2008 (has links)
The mechanical pulping industry has been developing throughout the years, due to competitive prices in the electricity market and good accessibility of wood. This has made it possible for such and “expensive” process to further develop. Today, with increasing electricity prizes, it is of great interest to reduce electrical consumption in mechanical pulping industry, since the process consumes large amounts of electricity. Braviken paper mill is starting up a new thermomechanical pulping line, scheduled for start-up in August 2008, which aims to reduce electrical consumption. The new line will include chip pre-treatment equipment such as an impregnator, an Andrtiz Impressafiner (Screw press), a high intensity primary stage refines double disc (DD), and a new low consistency refiner (LC), significantly bigger than those earlier available on the market. This master´s thesis is one out of three Master´s thesis made at Braviken paper mill during spring 2008. They all are connected, and are investigating the possibility to reduce electric energy consumption within TMP production. Master´s thesis concerning high consistency refining was done by Dino Muhic, “High consistency refining of mechanical pulps during varying refining conditions”, and low consistency refining written by Fredrik Johansson “Increased energy efficiency in low consistency refining”. Chip pre-treatment is to be used to reduce electrical consumption. Mechanical pre-treatment, such as using an Andrtiz Impressafiner demolishes the chips while also making it possible to impregnate the chips with chemicals, the later giving additional possibilities to reduce electricity consumption. Chemical chip pre-treatment decreases the lignin softening temperature, which benefits the refining process, yielding longer and less damaged fibers that will create a fibrous pulp with reduced electrical energy input.The goal for this study was to investigate the effect of alkaline-peroxide on chip pre-treatment by using a design of experiment method, in terms of electric energy consumption for the process, strength properties, opacity and ISO-brightness within the pulp/sheets. The trials were built up as a factorial experiment, with two factors, alkaline and peroxide, with two levels each (high and low). The high level for alkaline was 15 kg/t and 10 kg/t for the low level, and the high level for peroxide was 10 kg/t and 5 kg/t for the low level. This resulted in four trials with two zero-points, and two reference pulps, one normal TMP, thermomechanical pulp, and the other TMP with pressafiner and water. The trials showed that adding alkaline-peroxide clearly had an impact on pulp properties, such as increased strength properties, fiber length improvements and less shives could be found in the alkaline-peroxide treated pulps. The yield was highest for the normal TMP, about 99% and it decreased with increasing alkaline addition, the lowest value was achieved for the pulps containing the highest dose of alkaline, about 95%. The optical properties were more or less as expected. Opacity had the highest value for the pulps that had been made from chips with the highest total alkaline level. The ISO brightness was highest for pulps containing low level of alkaline. It could not be decided if the electricity demand had been reduced for the chemically treated pulps; it actually had the opposite effect as expected. The chemically treated pulps demanded a higher SEC, specific energy consumption, compared to the reference pulps. This result could have depended on the small pilot plant high consistency refiners at CTP, Centre technique du papier, Grenoble, France, due to the plate size and what kind of plats that were used. To do trials like this and to be able to draw correct conclusions relevant for a full scale plant, bigger refiners might give a more comparable result. It was clear that the fiber properties had improved, which could be the key to reduce electricity when LE- (low-energy) plates are used in the HC-refiner. A higher intensity could be used and electricity energy could be saved.
50

Mechanical and chemical chip pre-treatment in mechanical pulp production

Sjölin, Malin January 2008 (has links)
<p> </p><p><p>The mechanical pulping industry has been developing throughout the years, due to competitive prices in the electricity market and good accessibility of wood. This has made it possible for such and “expensive” process to further develop. Today, with increasing electricity prizes, it is of great interest to reduce electrical consumption in mechanical pulping industry, since the process consumes large amounts of electricity. Braviken paper mill is starting up a new thermomechanical pulping line, scheduled for start-up in August 2008, which aims to reduce electrical consumption. The new line will include chip pre-treatment equipment such as an impregnator, an Andrtiz Impressafiner (Screw press), a high intensity primary stage refines double disc (DD), and a new low consistency refiner (LC), significantly bigger than those earlier available on the market. This master´s thesis is one out of three Master´s thesis made at Braviken paper mill during spring 2008. They all are connected, and are investigating the possibility to reduce electric energy consumption within TMP production. Master´s thesis concerning high consistency refining was done by Dino Muhic, “<em>High consistency refining of mechanical pulps during varying refining conditions</em>”, and low consistency refining written by Fredrik Johansson “I<em>ncreased energy efficiency in low consistency refining</em>”.</p><p><p>Chip pre-treatment is to be used to reduce electrical consumption. Mechanical pre-treatment, such as using an Andrtiz Impressafiner demolishes the chips while also making it possible to impregnate the chips with chemicals, the later giving additional possibilities to reduce electricity consumption. Chemical chip pre-treatment decreases the lignin softening temperature, which benefits the refining process, yielding longer and less damaged fibers that will create a fibrous pulp with reduced electrical energy input.The goal for this study was to investigate the effect of alkaline-peroxide on chip pre-treatment by using a design of experiment method, in terms of electric energy consumption for the process, strength properties, opacity and ISO-brightness within the pulp/sheets. The trials were built up as a factorial experiment, with two factors, alkaline and peroxide, with two levels each (high and low). The high level for alkaline was 15 kg/t and 10 kg/t for the low level, and the high level for peroxide was 10 kg/t and 5 kg/t for the low level. This resulted in four trials with two zero-points, and two reference pulps, one normal TMP, thermomechanical pulp, and the other TMP with pressafiner and water.</p><p>The trials showed that adding alkaline-peroxide clearly had an impact on pulp properties, such as increased strength properties, fiber length improvements and less shives could be found in the alkaline-peroxide treated pulps. The yield was highest for the normal TMP, about 99% and it decreased with increasing alkaline addition, the lowest value was achieved for the pulps containing the highest dose of alkaline, about 95%. The optical properties were more or less as expected. Opacity had the highest value for the pulps that had been made from chips with the highest total alkaline level. The ISO brightness was highest for pulps containing low level of alkaline. It could not be decided if the electricity demand had been reduced for the chemically treated pulps; it actually had the opposite effect as expected. The chemically treated pulps demanded a higher SEC, specific energy consumption, compared to the reference pulps. This result could have depended on the small pilot plant high consistency refiners at CTP, Centre technique du papier, Grenoble, France, due to the plate size and what kind of plats that were used. To do trials like this and to be able to draw correct conclusions relevant for a full scale plant, bigger refiners might give a more comparable result. It was clear that the fiber properties had improved, which could be the key to reduce electricity when LE- (low-energy) plates are used in the HC-refiner. A higher intensity could be used and electricity energy could be saved.</p></p></p>

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