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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.
201

Integrating Chemical Looping Gasification for Hydrogen Generation and CO2 Capture in Pulp Mills / Integrering av Chemical Looping Gasification för Generering av Vätgas samt CO2 Infångning på Massabruk

Palmér, Matilda January 2022 (has links)
Utsläpp av CO2 till atmosfären bidrar till ökningen av globala temperaturer. Industrisektorn står för 20 % av utsläppen och utav dessa kommer 6 % från pappers- och massaindustrin. För att lyckas minska den globala temperaturhöjningen till under 1,5 °C hjälper det inte bara att minska utsläppen. Även negativa utsläpp måste genereras. Syftet med denna studie är att undersöka implementeringen av CLG för att separera CO2 på ett energieffektivt sätt och samtidigt generera H2 och elektricitet. Processanalyser genomfördes för att undersöka möjligheten att implementera CLG-processen till ett typiskt massabruk. Processmodeller togs fram for att undersöka CLG, värmeåtervinning samt elektricitetsgenerering. Processmodellerna utvecklades med hjälp av Aspen Plus och Aspen HYSYS. De framtagna modellerna analyserades sedan med avseende på olika designparametrar inom CLG-processen. På ett typiskt massabruk som producerar 800 000 adt varje år kan 375 kg CO2/adt separeras och då uppnå negativa utsläpp, genom att byta ut multi-fuel forsrännaren med en CLG process. Den framtagna processmodellen skulle också kunna generera 360-504 kWh/adt av H2 beroende på de designparametrar som används för CLG-processen. Enligt modellen kan värme som återvinns från processen användas för att fånga upp ytterligare 13 % av CO2 från andra delar av bruket. Processanalys för olika designparametrar inom CLG systemet så som temperatur, luftflöde och flödet av syrgasbärare har presenterats. Nyckeltalen som undersöktes var den mängd CO2 som kunde fångas upp, mängd H2 genererad samt överskottet av elektricitet som produceras när multi-fuel förbränningen byts ut mot en CLG-process på ett typiskt massa bruk. / Emissions of CO2 to the atmosphere are contributing to the global temperature rise. The industrial sector contributed to 20 % of the emissions and out of that, 6 % are generated from the pulp and paper industry. To limit the temperature increase below 1,5 °C, the emissions not only need to be reduced but also negative emissions should be generated from different sectors. The purpose of this study is to realize the implementation of Chemical Looping Gasification (CLG) to separate CO2 (for permanent storage) in an energy-efficient way while co-generating H2 as well as electricity. Process analysis was carried out to investigate the possibility of substituting the multifuel boiler in a typical pulp mill with a CLG process. Process models for the CLG, heat recovery and electricity generation process were developed using AspenPlus and Aspen HYSYS. The process was analysed for different design conditions (temperature, autothermal condition, air flow, oxygen carrier flow) in the CLG process. It was found that in a typical pulp mill producing 800 000 adt per year, 375 kg- CO2/adt (14 % of total emissions from the process) can be inherently separated for storage to achieve negative emissions, if the multi-fuel boiler is replaced with a CLG unit. This process will also be able to generate 360-504 kWh/adt H2 depending on the design conditions in the CLG process. Heat recovered from the CLG unit can be utilized in capturing approximately 13 % additional CO2 from other sources in the pulp mill. Process analysis for different design conditions in CLG (temperature, airflow, oxygen carrier flow) have been presented. The key performance indicators were CO2 capture rates, H2 generated and net electrical output from the process.
202

Process and techno-economic analysis of a compact CO2 capture technology / Process och tekno-ekonomisk analys av ett kompakt CO2 infångningsteknik

Salvador Palacios, Nestor January 2023 (has links)
Den stora oron för de ökade växthusutsläppen och klimatförändringas effekter har uppmuntrat utvecklingen av åtgärder för att motverka de negativa konsekvenserna. En av de tekniker som har uppmärksammats under de senaste decennierna är kolavskiljningstekniken. Men nuförtiden är kolavskiljning en teknik som är relaterad till höga kostnader där både kapital- och driftskostnaderna är höga. Därför utfördes i detta projekt ett försök att minska kostnaden genom att ersätta den absorptionspackade kolonnen med ett nytt kompakt system. I detta fall atomiserade det kompakta systemet lösningsmedlet till droppar för att öka massöverföringen av koldioxidabsorptionen. Syftet med detta projekt var att utföra en jämförande teknisk-ekonomisk utvärdering av den konventionella kemiska absorptionsprocessen med packade kolonner mot en process med ett kompakt system. En processmodell för den konventionella processen etablerades i Aspen Plus. Dessutom manipulerades den berikade lösningen i samma processmodell för att simulera den förbättrade absorptionen på grund av atomatiseringen av lösningsmedlet. Det resulterade i att implementeringen av det kompakta systemet kunde generera tekniska förbättringar som ett minskat användande av lösningsmedel och en lägre återkokningsbelastning i regenereringskolonnen. Det var dock ingen betydande minskning av den totala fångstkostnaden. I det här fallet var de främsta bidragande faktorerna till fångstkostnaden var kompressorkostnaden och det höga elpriset. Känslighetsanalysen visade dock i huvudsak att fångstkostnaden skulle kunna sänkas när elpriset är lägre. Man kan dra slutsatsen att kompakta system är en lovande teknik som skulle kunna bidra till utvecklingen av kolavskiljningstekniken. Framtida undersökningar av processdesignen krävs dock för att sänka fångstkostnaden ännu mer. / The great concern regarding the increased greenhouse emissions and the effects of the climate change has encouraged the development of solution in order to counteract the negative consequences. One of the technologies that has gained attention during the last decades has been the carbon capture technology. However, nowadays the carbon capture has been a technology that has been related to high capture costs where both capital and operational costs usually has been high. Therefore, in this project, an attempt was realized to reduce the capture cost by replacing the absorption packed column with a novel compact system. In this case, the compact system atomized the solvent into droplets in order to enhance the mass transfer of the carbon dioxide absorption. The aim of this project was to perform a comparative techno-economical evaluation of the conventional chemical absorption process with packed columns to a process with a compact system. A process model for the conventional process was established in Aspen Plus. Furthermore, the rich loading was varied in the same process model in order to simulate the enhanced absorption due to the atomization of the solvent. It resulted that the implementation of the compact system could generate technical benefits such as a reduced solvent utilization and a lower reboiler duty in the stripper column. However, there was no significant reduction regarding the total capture cost. In this case, the main contributors to the capture cost were the compressor cost and the high electricity price. Nevertheless, the sensitivity analysis showed principally that the capture cost could be reduced if the power required in the flue gas compressor can be reduced. It could be concluded that the compact system is a promising technology that could contribute to a further development of the carbon capture technology. However, future investigations regarding the process design are required in order reduce the capture cost even more.
203

Carbon capture using aerosol technology / Koldioxidavskiljning med hjälp av aerosolteknik

Meus, Pierre January 2023 (has links)
Utveckling av en innovativ teknologi för koldioxidavskiljning med användning av aerosoldroppar av en kaliumkarbonatlösning. Laboratorieexperiment för att studera koldioxidabsorptionsprocessen under olika driftsförhållanden (temperatur, K2CO3- och CO2-koncentration, mängd genererad aerosol) / Development of an innovative technology for carbon capture using aerosol droplets of a potassium carbonate solution. Laboratory experiments to study CO2 absorption process with various operating conditions (temperature, K2CO3 and CO2 concentration, amount of aerosol generated)
204

Chemical Manufacturing in Developing Markets: Analysis and Cost Estimations

Wasiu Peter Oladipupo (8669685) 28 July 2023 (has links)
<p>Developed countries have built wealth and prosperity on the strength of their manufacturing sectors, with China’s success story of lifting 800 million people out of extreme poverty in 30 years a sterling and most recent example of how manufacturing-led industrialization can foster economic development. Sub-Saharan Africa, unfortunately, find itself today in a similar situation as China did in 1990, with over 50% of the world’s desperately poor 719 million people living in the region. But unlike China, Sub-Saharan Africa is faced with the additional challenge of overcoming poverty in a world with stricter constraints to global trade and climate change limitations to modern-day industrialization. Compounding the challenges further is the region's limited know-how and human capital — a consequence of years of underdevelopment, creating a classic chicken and egg dilemma where the lack of industrialization perpetuates the dearth of know-how and human capital, and vice versa.</p><p>Considering these challenges, we investigate how chemical manufacturing and what chemical manufacturing approaches can be leveraged to effectively drive industrialization and economic development in Sub-Saharan Africa. We propose chemicals manufacturing using prefabricated modules – which are constructed offsite in places with available human capital and transported to be assembled in places where they are needed – as a flexible and needed approach. However, Economy of Scale, which generally favors large-scale chemical manufacturing, poses as a major constraint to such modularization approach, especially given the presently small serviceable market sizes in Sub-Saharan Africa due to low purchasing power parity. We thus utilize mathematical modeling techniques to determine and establish scenarios for economic viability of the proposed approach, providing modeling frameworks and introducing measures for further studies in the process. We also provide and analyze exemplary flowsheets synthesized for a net-zero carbon emissions chemical manufacturing paradigm in the region.</p><p>This work concludes with a prefeasibility study of a chemical manufacturing project in Nigeria, as part of the author’s quest to build prefabricated modular plants across Africa. <i>Modular plants are attractive as they can be tuned to market demand of a developing market and region that needs them, putting less capital at risk.</i></p><p>This thesis is intended to be a vanguard of potential solutions to the complex challenges to industrialization in Sub-Saharan Africa. It endeavors to pave the way for addressing these issues through chemical manufacturing, offering valuable insights for sustainable progress.</p>
205

Measurement and Analysis of Gas Composition in a Staged and Unstaged Oxy-Fired Pulverized Coal Reactor with Warm Flue Gas Recycle

Chamberlain, Skyler Charles 05 July 2012 (has links) (PDF)
Nearly half of the electrical power produced in the United States is generated with coal. Coal power is inexpensive and reliable, but coal combustion releases harmful pollutants including NOx and SOx into the atmosphere if not controlled. CO2, a greenhouse gas, is also released during coal combustion and may contribute to global warming. A promising technology enabling carbon capture is oxy-coal combustion. During oxy-combustion, coal is burned in an atmosphere of O2 and recycled flue gas to eliminate nitrogen which makes up the majority of air-combustion flue gas. Oxy-combustion flue gas is mainly composed of CO2 and H2O. H2O can be condensed out of the gas, and the CO2 can then be captured and permanently stored relatively easily. The composition of the gas inside an oxy-fired boiler will be different due to the absence of nitrogen and the recycling of flue gas. Corrosive sulfur and chlorine gas species concentrations will be higher, and CO and NOx concentrations will be effected. An understanding of the differences in gas concentrations is critical to oxy-combustion boiler design. Four different pulverized coals were combusted in a reactor under staged and unstaged oxy-combustion conditions with warm recycled flue gas (420°F) to simulate conditions in an oxy-fired coal boiler. The gas composition was measured in the reducing and oxidizing zones for staged combustion, and in the same locations, 57 cm and 216 cm from the burner, for unstaged combustion. The results were compared to the results from similar staged air-combustion experiments using the same coals and burner. CO concentrations were higher for staged oxy-combustion compared to air-combustion, and the increase was more substantial for lower rank coals. H2S concentrations in the reducing regions were also higher, and the fraction of gas phase sulfur measured as H2S was higher for oxy-combustion. SO2 concentrations were 2.9 to 3.8 times as high as air-combustion concentrations. The measured conversion of coal sulfur to SO3 was lower for oxy-combustion, and ranged from 0.61% to 0.98%. The average fraction of coal sulfur measured in the gas phase was 84%, 80%, and 85% for staged oxy-combustion, unstaged oxy-combustion, and staged air-combustion respectively. HCl concentrations were 2.8 to 3.1 times higher in the staged oxy-combustion oxidizing zone, and a smaller fraction of coal chlorine was measured in the reducing zone. On average 70.8%, 79.5%, and 71.1% of the coal chlorine was measured as HCl for staged oxy-combustion, unstaged oxy-combustion, and staged air-combustion respectively. The fractions of coal chlorine and sulfur measured in the gas phase for staged combustion were not significantly affected by combustion media. Some staged oxy-combustion NO concentrations were lower than air-combustion concentrations while others were slightly higher, and NO emission rates were much lower due to recycling NO through the burner.
206

Engineering Properties, Hydration Kinetics, and Carbon Capture in Sustainable Construction Materials

Tran, Thien Quoc 20 December 2023 (has links)
Concrete, the second most consumed material on earth after water, is a source of environmental problems due to global urbanization. The production of this construction material requires a large amount of natural resources, and portland cement (PC) is responsible for around 8 % of planet-warming CO2 emissions. Producing 1 ton of PC will release roughly 1 ton of CO2 into the atmosphere. In 2021, around 92 million metric tons of PC were produced in the U.S., and a total of 4.4 billion tons were manufactured worldwide. While there was a yearly increase of around 1.5 % in the direct CO2 intensity of cement production from 2015 to 2021, urgent annual declines of 3 % until 2030 are necessary to be in line with the Net Zero Emissions by 2050 Scenario. This dissertation presents different approaches and technologies to offset the CO2 footprint of the production of cement clinker, concrete, and cementitious materials in general. First, this dissertation investigated the possibility of using end-of-life tire (ELT) rubber powder and its zinc-recovered residual (treated ELT rubber) to partially replace fine aggregates of different construction and infrastructure materials including stabilized soft soil (0 %, 10 %, 30 %, and 50 % ELT rubber added by clay volume), portland cement concrete (0 %, 10 %, 20 %, and 30 % ELT rubber added by sand volume), and asphalt concrete (20 % ELT rubber added by sand volume). This work was discussed through aspects of engineering properties and environmental impacts. The results reveal that the ELT rubber had both negative and positive effects on the engineering properties of the three materials while this waste posed a huge leachability of zinc and total organic carbon (TOC) content when being subjected to aqueous environments. However, the findings indicate that all three materials' matrices could effectively immobilize most leachable zinc from the ELT rubber by more than 90 %. Meanwhile, only stabilized soft soil and asphalt concrete could effectively deal with leachable TOC content from ELT rubber, and portland cement concrete needed the addition of silica fume to reduce TOC concentration in its leachate. Second, while previous studies have shown that steel furnace slag (SFS) can stabilize clay soils, the evidence is not clear if the stabilization mechanism is chemical and/or mechanical. This dissertation used isothermal calorimetry (IC) to quantify the heat of hydration of the mixture to assess the chemical aspects of the stabilization. Specifically, kaolin and bentonite clays were each blended with 40 % SFS by mass at water-to-binder ratios ranging from 1.0 to 1.5. The hydration properties of stabilized mixtures using lime or PC were also tested for comparison at the same experimental conditions. The obtained thermal power and total heat curves of stabilized mixtures confirmed that, for the specific SFS in this study, there is a hydration process taking place in clay stabilized by SFS. Relative to lime and PC, the SFS performed similarly in terms of heat of hydration behavior. When blended into clays, SFS provided a more significant heat of hydration behavior than cement, but that was much milder than lime. X-ray diffraction (XRD) and thermogravimetric analysis (TGA) were also employed to qualitatively analyze the mineralogy of the stabilized mixtures. Finally, this dissertation adopted a Digestion-Titration Method (DTM) for the determination of CO2 content in cementitious materials that has been mineralized in the form of calcium carbonate (CaCO3). This method was modified based on tests that were originally developed in the early 1900s. The method uses hydrochloric acid to digest CaCO3 under vacuum conditions. The CO2 released is captured by a barium hydroxide solution, which is then titrated to quantify the amount of CO2 absorbed. A design of experiments approach was used to optimize the experimental conditions. Samples of known CaCO3 content were first evaluated to establish the baseline test performance, and additional tests were performed on portland cement and various rock samples. The results were also compared to TGA, including a discussion to compare the two test methods. The data suggest that the new test method is feasibly applicable to chemically determine the CO2 captured in cementitious materials, and it can be an alternative method for TGA with lower experimental cost and easier access. Overall, it is evident that cement, concrete, and construction materials are essential to the functionality of civilization. Dealing with CO2 emissions and natural resource depletion induced by the production of these construction materials is urgent for sustainable development. Attempts toward construction materials with lower embodied CO2 by using low-carbon aggregates (e.g., waste aggregates, recycled aggregates) and alternative cementitious binders while controlling the environmental effects of the utilized waste materials are currently viable sustainable approaches. In addition, tools or new test methods that can support measuring the effectiveness of these reduced carbon cementitious materials are necessary. This dissertation investigates the feasibility of the use of ELT rubber waste in construction materials to reduce the exploitation of natural resources considering engineering properties and environmental impacts. It also provides a deeper understanding of the hydration behavior of stabilized soil using SFS which is expected to partially or fully replace PC in the material. Experimentally, it develops a chemical test model as an alternative method for TGA with lower experimental cost, less interference, and easier access to determine the CO2 captured in cementitious materials. / Doctor of Philosophy / Concrete, the second most consumed material on earth after water, is a source of environmental problems due to global urbanization. The production of this construction material requires a large amount of natural resources, and portland cement (PC) is responsible for around 8 % of planet-warming CO2 emissions. This dissertation presents different approaches and technologies to offset the CO2 footprint of the production of construction materials (i.e., cement clinker, concrete, and general cementitious materials). First, this dissertation investigated the possibility of using end-of-life tire (ELT) rubber powder in different construction materials including stabilized soft soil, portland cement concrete, and asphalt concrete. This work was discussed through aspects of engineering properties and environmental impacts. The results reveal that the ELT rubber had both negative and positive effects on the engineering properties of the three materials. In return, all three materials' matrices could effectively immobilize most leachable zinc and total organic carbon (TOC) from the ELT rubber, which are detrimental to aquatic animals, plants, and humans. Second, this dissertation used isothermal calorimetry (IC) for the first time to study the heat of hydration of soil stabilized by steel furnace slag (SFS) to assess the chemical aspects of the stabilization. The work compared the hydration behavior of SFS in clayey soil with traditional stabilizers such as lime or portland cement. The results demonstrated that there were chemical reactions taking place during the hydration of stabilized soil using SFS, explaining the improvement in engineering properties of the stabilized soil. Moreover, this dissertation adopted a Digestion-Titration Method (DTM) for the determination of mineralized CO2 content in cementitious materials. The method uses hydrochloric acid to digest CaCO3 under vacuum conditions. The CO2 released is captured by a barium hydroxide solution, which is then titrated to quantify the amount of CO2 absorbed. The data suggest that the new test method is feasibly applicable to chemically determine the CO2 mineralized in cementitious materials, and it can be an alternative method for thermogravimetric analysis with lower experimental cost and easier access. Overall, it is evident that cement, concrete, and construction materials are essential to the functionality of civilization. Dealing with CO2 emissions and natural resource depletion induced by the production of these construction materials is urgent for sustainable development. This dissertation is expected to fill the knowledge gap in carbon neutral construction materials research, including increasing the use of low-carbon aggregates (e.g., waste aggregates, recycled aggregates) and alternative cementitious binders as well as developing new test methods that can support measuring the effectiveness of these reduced carbon cementitious materials.
207

Comparative Techno-Economic Analysis of Carbon Capture Processes: Pre-Combustion, Post-Combustion, and Oxy-Fuel Combustion Operations

Kheirinik, M., Ahmed, Shaab, Rahmanian, Nejat 13 December 2021 (has links)
Yes / Evaluation of economic aspects is one of the main milestones that affect taking rapid actions in dealing with GHGs mitigation; in particular, avoiding CO2 emissions from large source points, such as power plants. In the present study, three kinds of capturing solutions for coal power plants as the most common source of electricity generation have been studied from technical and economic standpoints. Aspen HYSYS (ver.11) has been used to simulate the overall processes, calculate the battery limit, and assess required equipment. The Taylor scoring method has been utilized to calculate the costliness indexes, assessing the capital and investment costs of a 230 MW power plant using anthracite coal with and without post-combustion, pre-combustion, and oxy-fuel combustion CO2 capture technologies. Comparing the costs and the levelized cost of electricity, it was found that pre-combustion is more costly, to the extent that the total investment for it is approximately 1.6 times higher than the oxy-fuel process. Finally, post-combustion, in terms of maturity and cost-effectiveness, seems to be more attractive, since the capital cost and indirect costs are less. Most importantly, this can be applied to the existing plants without major disruption to the current operation of the plants.
208

Toward the Industrial Application of a Solid-Oxide Fuel Cell Power Plant with Compressed Air Energy Storage / Design, Simulation, Optimization, Techno-Economic Analyses and Life-Cycle Analyses of Solid-Oxide Fuel Cell Power Plants

Nease, Jacob January 2016 (has links)
The global electricity generation industry is very reliant on the use of fossil fuels, particularly natural gas and coal. However, it is quickly becoming a reality that the over-consumption of these resources will continue to lead to significant global damage via global warming, ecosystem destruction, and the depletion of these so-called non-renewable re-sources. To combat this issue, renewable sources such as wind, biofuels and solar are be-coming much more prevalent in the power generation industry, but significant economic, reliability and availability barriers to entry will prevent these sources from being major contributors to the power industry for decades. To this end, this thesis focuses on the design, operation, optimization and life cycle analysis of an integrated solid-oxide fuel (SOFC) cell power plant integrated with com-pressed air energy storage (CAES). This plant, fueled by either natural gas or coal, can make much more efficient use of their limited non-renewable fuel sources, and are capable of achieving nearly 100% carbon capture at the plant boundary. This plant is intended to serve as a more efficient and environmentally responsible alternative to current power generation methods while still exploiting remaining fossil fuels to their fullest extent. This thesis details the design, sizing and simulation of integrated SOFC/CAES plants in Aspen Plus so that full feasibility and techno-economic analyses may be performed, the results of which are then compared to the current state-of-the-art (SOTA) options. In order to compare the plants on an environmental level, full cradle-to-grave life-cycle analyses using the ReCiPe 2008 method are completed for each SOFC-based plant and all comparable SOTA options under a wide range of assumptions and plant configurations, such as the use of carbon capture strategies. Furthermore, detailed reduced-order dynamic models of the integrated SOFC/CAES plants are developed and simulated with a newly developed rolling-horizon optimization method to assess the load-following capabilities of the integrated plant. Real scaled demand data for the market of Ontario, Canada for the years 2013 and 2014 are used as the demand data for the simulations. This thesis takes strides in proving the feasibility of an integrated SOFC/CAES power plant for providing clean, efficient, reliable and cost-effective power using fossil fuels. The next steps for this project involve the development of a lab-scale pilot plant, which would be used to validate simulation results and provide an opportunity for the real-time application and assessment of the potential of this plant design. / Thesis / Doctor of Philosophy (PhD)
209

Control of carbon dioxide capture from biomass CHP plants : Designing a suitable control system to realize the flexible operation of the CO2 capture system

Rout, Tanmmay January 2023 (has links)
This degree project studies the integration of carbon capture system into biomass fired combined heat and power (bio-CHP) plants. The key disturbances from bio-CHP plants include flue gas flow rate, carbon dioxide (CO2) concentration and available heat for the reboiler because the use of versatile biomass and the dynamic operation of CHP plants results in large fluctuations in the properties of flue gas and the heat input for CO2 capture. To clearly understand the impacts of these disturbances on the performance of CO2 capture, a dynamic CO2 capture model is developed in Aspen Plus Dynamics by using monoethanolamine (MEA) based chemical absorption. Proportional-Integral (PI) feedback controllers are then implemented to further study and compare the performance of the CO2 capture process under different control strategies, the performance with general control settings and fine-tuned controllers are obtained and compared, including both the control performance and system performance. The control performance includes the maximum deviation and settling time, which could reflect only the performance of the controllers.  The system performance includes Captured CO2, reboiler duty and Energy penalty per unit CO2 captured, which could reflect CO2 capture system performance. An equilibrium stage steady state model is first developed for the key components in the CO2 capture plant in Aspen Plus, consisting of the absorber, the stripper, and lean-rich heat exchanger. By sizing the components and employing the pressure driven mode, the steady state model is enabled to be a dynamic model. The disturbances about flue gas and reboiler heat are taken from a real bio-CHP plant in Sweden. Considering the higher flue gas flowrate, the model has been scaled up to meet the requirement of this bio-CHP plant. The addition of controllers are done for the flexible operation of the CO2 capture system and the controlled variables considered in this study are the percentage of CO2 absorbed in the absorber column, reboiler temperature and rich solvent flow in the stripper column. The results show the effects of fluctuations in the key influencing factors on the control performance and the system performance . The fine-tuned controller implemented system showcases better performance when the quantity of CO2 captured is compared with that of the system in the absence of controllers, where a 1.1% increase in the amount of captured CO2 is observed when the flue gas flow rate is increased by 30%. The system also maintains a 1.8% higher capture rate when controllers are implemented. This showcases better system performance when controllers are implemented in the system. To further analyse the effects of control strategies two different control strategies are compared where controllers with general settings are compared to the controllers which are fine-tuning achieved by implementing tuning parameters which were obtained through Internal Model control (IMC) based on the system requirements. The fine tuning of the controllers results in improved system performance where the amount of captured CO2 increases by 1.4% when the reboiler duty is increased by 30% and a 1.7% decrease in the energy penalty per unit CO2 captured. Additionally, the results show that the settling time and maximum deviation are different for the two controllers where the controller which underwent fine tuning maintained the steady set point whereas the controller with general controller tuning showcases deviation before it attained stability. Therefore, the fine-tuned controller is more efficient to enable the flexible operation of CO2 capture when facing disturbance. It is studied that the tuning parameters implemented in the controllers affect the transient operation of the plant and improved the dynamic performance of the capture system. The tuned controllers offered more stability to the capture system while attaining their respective set points in a shorter time frame. It is also found that there exists a big difference between the system’s performance without controllers and that with finely tuned controllers. The difference in captured CO2 amount is approximately 26 ton/h when flue gas flow rate increases by 30%. The percentage difference is 1.1%, 7.7% and  5.9% for Captured CO2, reboiler duty and Energy penalty per unit CO2 captured respectively. In conclusion the control of the transient operation of the CO2 capture system needs the control system implemented and requires fine tuning parameters to achieve the desirable performance.
210

Techno-economic Assessment of Carbon Capture from Low Concentration Streams

Joshi, Prithvi Kiran January 2023 (has links)
Investments in carbon capture from industrial emissions have been on the rise in recent years, having reached over $200 million in 2021 as compared to 2015’s $13 million. The Paris Agreement, signed by 196 parties globally in 2015, is purported to be the primary driver for this, with its ambitious goal of limiting global surface temperature rise to 1.5°C by the year 2100 as compared to the pre-industrial era. Achievement of a carbon-neutral future for industries has been sought by experts in more than a few ways, which include attempts directed towards re-designing current manufacturing processes to produce inherently low CO2 emissions. Although eventual elimination of carbon emissions forms the ultimate goal, complete avoidance of CO2 production does not seem probable for all industrial sectors. Emissions from industries in the medium to long term are thus foreseen to be composed between 0.5% and 7% of CO2 by moles (roughly between 1% and 10% by mass), depending on the level of dilution occurring during the various flue gas treatment procedures between their source and the capture unit. An assessment of the capabilities of two popular and one prospective carbon capture technologies in capturing CO2 from such emissions of the future has been made in this work to aid investors make informed decisions about a suitable technology. The monoethanolamine-based (MEA) absorption system, one of the most popular choices today, was found to be well capable of treating emissions composed of CO2 in proportions as low as 0.6% by mole (or ∼1% by mass) with capture rates well over 95%. Its thermal energy intensity ranged between 3.59 MJth/kgCO2 captured and 10.23 MJth/kgCO2 captured with an associated levelised cost of capture ranging between €20.36/tonneCO2 captured and €141.97/tonneCO2 captured going from the 10% concentrated to the 1% concentrated stream by mass. In comparison, the benfield system was found to effect much lower CO2 capture rates ranging between 35% and 88%, making it unsuitable for treatment of low CO2 concentrated streams. Even with such poor performance at high pressures of operation, its energy demand ranged between 3.9 MJth/kgCO2 captured and 11.07 MJth/kgCO2 captured with an associated levelised cost of capture between €174.28/tonneCO2 captured and €4209.06/tonneCO2 captured. The immobilised amine-based system, in what is considered to be a non-optimised configuration yet, was found to capture nearly 100% of the entering CO2 with energy consumption ranging between 3.71MJth/kgCO2 captured and 11.8 MJth/kgCO2 captured for extremely high, but improvable levelised costs of capture ranging between €674.31/tonneCO2 captured and €3488.42/tonneCO2 captured. Exhibiting comparable energy performance to the mature MEA-based absorption system’s even in its non-optimised configuration, the immobilised amine-based adsorption system was found to possess potential to be the carbon capture technology of the future for treatment of low CO2-concentrated effluent streams. / Investeringar i koldioxidavskiljning från industriella utsläpp har ökat de senaste åren och nått över 200 miljoner USD 2021 jämfört med 2015 års 13 miljoner USD. Parisavtalet, som undertecknades av 196 parter globalt 2015, påstås vara den främsta drivkraften för detta, med det ambitiösa målet att begränsa den globala yttemperaturökningen till 1,5°C till år 2100 jämfört med den förindustriella eran. Att uppnå en koldioxidneutral framtid för industrier har eftersträvats av experter på mer än ett fåtal sätt, vilket inkluderar försök inriktade på att omdesigna nuvarande tillverkningsprocesser för att producera låga CO2-utsläpp. Även om fullständig eliminering av koldioxidutsläpp utgör det ideala målet, är det inte troligt att CO2-produktion kan undvikas helt för att alla industrisektorer. Utsläppen från industrier på medellång till lång sikt förväntas därför utgöra mellan 0,5 % och 7 % av CO2 per mol (ungefär mellan 1 % och 10 % i massa), beroende på nivån av utspädning som inträffar under de olika rökgasbehandlingsprocedurerna mellan utsläppskällan och fångstenheten. I det här arbetet har två traditionella och en potentiellt blivande koldioxidavskiljningsteknik jämförts och en bedömning av deras förmåga att fånga in CO2 från framtida utsläpp har gjorts i syfte att hjälpa investerare att göra ett klokt val. Det monoetanolaminbaserade (MEA) absorptionssystemet, ett av de mest populära valen idag, visade sig vara väl kapabelt att behandla utsläpp med CO2-koncentrationer så låga som 0,6 molprocent (eller 1 massprocent) med fångsthastigheter långt över 95 %. Dess termiska energiintensitet varierade mellan 3,59 MJth/kgCO2 captured och 10,23 MJth/kgCO2 captured med en tillhörande utjämnad kostnad för fångst mellan €20,36/tonCO2 captured och €141,97/tonCO2 captured från 10 % koncentrerad till 1 % koncentrerad ström i massa. Som jämförelse visade sig benfield-systemet ge mycket lägre CO2-avskiljningshastigheter på mellan 35 % och 88 %, vilket gör metodenolämplig för behandling av gasströmmar med låg CO2-koncentration. Den dåliga prestandan uppvisades trots höga drifttryck och metoden medförde en energiintensitet mellan 3,9MJth/kgCO2 captured till 11,07MJth/kgCO2 captured samt en snittkostnad mellan €174/tonCO2 captured till €4209,06/tonCO2 captured. Det immobiliserade aminbaserade systemet anses vara en icke-optimerad konfiguration men visade sig trots det fånga upp nästan 100 % av inkommande CO2 med en energiförbrukning på mellan 3,71 MJth/kgCO2 captured och 11,8 MJth/kgCO2 captured. De extremt höga, men dock förbättringsbara, snittkostnaderna för infångningen sträcker sig mellan €674/tonCO2 captured och €3488,42/tonCO2 captured. Det immobiliserade aminbaserade adsorptionssystemet uppvisar jämförbar energiprestanda som det mogna MEA-baserade absorptionssystemet även i sin icke-optimerade konfiguration.

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