939 research outputs found
Study of hydrogen liquefaction process through modelling and simulation
No full textHydrogen is viewed as a promising alternative energy source to reduce dependence on conventional fuels, helping to tackle issues such as environmental challenges (climate changes) coming especially from the energy sector. Storing and delivering hydrogen efficiently can be achieved by converting it into its cryogenic liquid form. However, producing liquid hydrogen in industrial settings is both energy-intensive and costly. Current industrial hydrogen liquefaction plants are built for relatively small-scale operations that require a substantial amount of energy to liquefy hydrogen. As the future demand for hydrogen as an energy carrier grows, there will be a need for large-capacity hydrogen liquefaction plants to meet this demand. To deliver liquid hydrogen as an energy carrier, effective and viable hydrogen liquefaction processes are required. In this view, the thesis presents a study of hydrogen liquefaction process through modelling and simulation. A thorough technical review paper was developed to evaluate the past, current, and future of hydrogen liquefaction, followed by a technical paper on the evaluation of the significance of ortho-para-hydrogen conversion in the hydrogen liquefaction process leading to the development of a novel approach. All studied process concepts were modelled and simulated in Aspen Plus, a comprehensive process simulator, under a steady-state condition. To evaluate the viability, a detailed energy and exergy estimation for the hydrogen liquefaction process (including process subsystems and the process equipment) was implemented. The implemented hydrogen liquefaction process simulation and model estimations were used for the efficient determination of the hydrogen liquefaction process for both specific energy consumption (SEC), exergy efficiency, and coefficient of performance (COP). Finally, a 100 TPD capacity of hydrogen liquefaction process was developed which adopted a Claude Cycle of high-pressure hydrogen with Joule-Brayton and Mixed-refrigerant precooling. The hydrogen liquefaction process developed reduces the SEC of an average developed hydrogen liquefaction model (like that of Linde AG Plant) by nearly 70% to about 3.263 kWh/kgLH2, increases the exergy efficiency to 95.85%, and produces a COP of 0.3878. The results presented in this work are anticipated to substantially lead to reducing the cost of hydrogen liquefaction and enable hydrogen as the fuel of the future
Study of hydrogen liquefaction process through modelling and simulation
No full textHydrogen is viewed as a promising alternative energy source to reduce dependence on conventional fuels, helping to tackle issues such as environmental challenges (climate changes) coming especially from the energy sector. Storing and delivering hydrogen efficiently can be achieved by converting it into its cryogenic liquid form. However, producing liquid hydrogen in industrial settings is both energy-intensive and costly. Current industrial hydrogen liquefaction plants are built for relatively small-scale operations that require a substantial amount of energy to liquefy hydrogen. As the future demand for hydrogen as an energy carrier grows, there will be a need for large-capacity hydrogen liquefaction plants to meet this demand. To deliver liquid hydrogen as an energy carrier, effective and viable hydrogen liquefaction processes are required. In this view, the thesis presents a study of hydrogen liquefaction process through modelling and simulation. A thorough technical review paper was developed to evaluate the past, current, and future of hydrogen liquefaction, followed by a technical paper on the evaluation of the significance of ortho-para-hydrogen conversion in the hydrogen liquefaction process leading to the development of a novel approach. All studied process concepts were modelled and simulated in Aspen Plus, a comprehensive process simulator, under a steady-state condition. To evaluate the viability, a detailed energy and exergy estimation for the hydrogen liquefaction process (including process subsystems and the process equipment) was implemented. The implemented hydrogen liquefaction process simulation and model estimations were used for the efficient determination of the hydrogen liquefaction process for both specific energy consumption (SEC), exergy efficiency, and coefficient of performance (COP). Finally, a 100 TPD capacity of hydrogen liquefaction process was developed which adopted a Claude Cycle of high-pressure hydrogen with Joule-Brayton and Mixed-refrigerant precooling. The hydrogen liquefaction process developed reduces the SEC of an average developed hydrogen liquefaction model (like that of Linde AG Plant) by nearly 70% to about 3.263 kWh/kgLH2, increases the exergy efficiency to 95.85%, and produces a COP of 0.3878. The results presented in this work are anticipated to substantially lead to reducing the cost of hydrogen liquefaction and enable hydrogen as the fuel of the future
Study of power plant, carbon capture and transport network through dynamic modelling and simulation
No full textThe unfavourable role of CO₂ in stimulating climate change has generated concerns as CO₂ levels in the atmosphere continue to increase. As a result, it has been recommended that coal-fired power plants which are major CO₂ emitters should be operated with a carbon capture and storage (CCS) system to reduce CO₂ emission levels from the plant. Studies on CCS chain have been limited except a few high profile projects. Majority of previous studies focused on individual components of the CCS chain which are insufficient to understand how the components of the CCS chain interact dynamically during operation. In this thesis, model-based study of the CCS chain including coal-fired subcritical power plant, post-combustion CO₂ capture (PCC) and pipeline transport components is presented. The component models of the CCS chain are dynamic and were derived from first principles. A separate model involving only the drum-boiler of a typical coal-fired subcritical power plant was also developed using neural networks.The power plant model was validated at steady state conditions for different load levels (70-100%). Analysis with the power plant model show that load change by ramping cause less disturbance than step changes. Rate-based PCC model obtained from Lawal et al. (2010) was used in this thesis. The PCC model was subsequently simplified to reduce the CPU time requirement. The CPU time was reduced by about 60% after simplification and the predictions compared to the detailed model had less than 5% relative difference. The results show that the numerous non-linear algebraic equations and external property calls in the detailed model are the reason for the high CPU time requirement of the detailed PCC model. The pipeline model is distributed and includes elevation profile and heat transfer with the environment. The pipeline model was used to assess the planned Yorkshire and Humber CO₂ pipeline network.Analysis with the CCS chain model indicates that actual changes in CO₂ flowrate entering the pipeline transport system in response to small load changes (about 10%) is very small (<5%). It is therefore concluded that small changes in load will have minimal impact on the transport component of the CCS chain when the capture plant is PCC
Study of power plant, carbon capture and transport network through dynamic modelling and simulation
No full textThe unfavourable role of CO₂ in stimulating climate change has generated concerns as CO₂ levels in the atmosphere continue to increase. As a result, it has been recommended that coal-fired power plants which are major CO₂ emitters should be operated with a carbon capture and storage (CCS) system to reduce CO₂ emission levels from the plant. Studies on CCS chain have been limited except a few high profile projects. Majority of previous studies focused on individual components of the CCS chain which are insufficient to understand how the components of the CCS chain interact dynamically during operation. In this thesis, model-based study of the CCS chain including coal-fired subcritical power plant, post-combustion CO₂ capture (PCC) and pipeline transport components is presented. The component models of the CCS chain are dynamic and were derived from first principles. A separate model involving only the drum-boiler of a typical coal-fired subcritical power plant was also developed using neural networks.The power plant model was validated at steady state conditions for different load levels (70-100%). Analysis with the power plant model show that load change by ramping cause less disturbance than step changes. Rate-based PCC model obtained from Lawal et al. (2010) was used in this thesis. The PCC model was subsequently simplified to reduce the CPU time requirement. The CPU time was reduced by about 60% after simplification and the predictions compared to the detailed model had less than 5% relative difference. The results show that the numerous non-linear algebraic equations and external property calls in the detailed model are the reason for the high CPU time requirement of the detailed PCC model. The pipeline model is distributed and includes elevation profile and heat transfer with the environment. The pipeline model was used to assess the planned Yorkshire and Humber CO₂ pipeline network.Analysis with the CCS chain model indicates that actual changes in CO₂ flowrate entering the pipeline transport system in response to small load changes (about 10%) is very small (<5%). It is therefore concluded that small changes in load will have minimal impact on the transport component of the CCS chain when the capture plant is PCC
In the light of Franco-Nigerian Literature: a conversation with Ramonu Sanusi, author of “Un nègre a violé une blonde à Dallas” (2016)
No full textAuthor of Un nègre a violé une blonde à Dallas (2016)
Dynamic modelling, validation and analysis of coal-fired subcritical power plant
No full textCoal-fired power plants are the main source of global electricity. As environmental regulations tighten, there is need to improve the design, operation and control of existing or new built coal-fired power plants. Modelling and simulation is identified as an economic, safe and reliable approach to reach this objective. In this study, a detailed dynamic model of a 500 MWe coal-fired subcritical power plant was developed using gPROMS based on first principles. Model validations were performed against actual plant measurements and the relative error was less than 5%. The model is able to predict plant performance reasonably from 70% load level to full load. Our analysis showed that implementing load changes through ramping introduces less process disturbances than step change. The model can be useful for providing operator training and for process troubleshooting among others
On "perskie oko" ("Persian eye") and on what is really Persian in Polish phrasemes
No full textPoza kobiercem i tkaninami, które rzeczywiście sprowadzano z Persji lub wytwarzano w naszych persjarniach, pozostałe rzeczowniki występujące w polskich konstrukcjach frazeologicznych z przymiotnikiem „perski” mają z Persją niewiele wspólnego. Podobnie jest z perskim kotem, który wcześniej był znany w Europie jako kot angorski (ankarski) i którego sprowadzano do Europy także z Turcji i Damaszku (kot damasceński). Tak samo perski proszek był w istocie pochodzenia kaukaskiego, karakuły wywodzą się z Azji Środkowej (miejscowość Karakul w Uzbekistanie), zaś perskie oko było francuskim kalamburem: l’œil perçant ‘oko bystre, przenikliwe’ wymawiane tak samo jak l’œil persan ‘perskie oko’The subject of the article are certain idiomatic expressions constructed with the adjective perski (‘Persian’) in Polish: perskie oko (‘Persian eye’), perski dywan (‘Persian carpet’), perski proszek (‘Persian powder’) etc. Moreover, the author attempts to answer the question: What do we have that is really perski (‘Persian’) in Polish? Are these phrases really related to Persia or Persians, or are they just a word game (homophones)? So far the origin of the most popular one, i.e. perskie oko (‘Persian eye’) has not been established even though a lively discussion on this subject was held on the pages of the Język Polski 90 years ago. It was started by Stanisław Szober who in his book Life of words, explained the origin of the phrase perskie oko for the first time, indicating that it is a semantic borrowing from French, and its basis is l’oeil perçant ‘piercing eye’. In response, Józef Birkenmajer claimed this popular phrase comes from Krakow, relating it – quite incredibly – to a Persian man on the label of the popular Zacherlin insecticide powder called perski proszek (‘Persian powder’). It turns out that the source of this expression was a French anecdote by Alphonse Karr from the late nineteenth century based precisely on the word game
Special issue on carbon capture in the context of carbon capture, utilisation and storage (CCUS)
No full textTechnical and Economic Analysis of Ionic Liquid-Based Post-combustion CO2 Capture Process
No full textInternational audiencePost-combustion CO2 capture (PCC) is considered the most feasible and viable process for CO2 abatement in the power sector. Aqueous monoethanolamine (MEA) solvent, traditionally used in this process, brings along challenges, namely, huge energy requirement for solvent regeneration, huge solvent flow rate leading to large equipment sizes, and chemical and thermal degradability, among others. In this study, the prospects of replacing aqueous MEA solvent with a blend of ionic liquid (IL) and MEA are explored. IL is generally chemically and thermally stable among other encouraging properties but is however expensive. A blend of IL and MEA is predicted to have shared qualities of MEA and IL and therefore could hypothetically contribute to meaningful reduction in overall cost of the process. This hypothesis is investigated in this study by performing a technical and economic analysis of the process using aqueous blend of IL ([Bpy][BF4]) and MEA as solvent. A rate-based model of the process developed in Aspen Plus was used to perform the technical and economic studies. Technical and economic analysis of PCC with aqueous blend of IL and MEA as solvent have not been covered in existing studies. Also, reported models are derived using equilibrium-based approach. From the analysis, it is found that with about 5, wt% IL concentration, total solvent cost approximates closely to typical solvent cost for the MEA only process; higher IL concentration leads to significant increase in solvent cost. Also, the simulation results showed that the rate-based [Bpy][BF4]-MEA process can save about 7–9% regeneration heat duty and reduce the solvent flow rate by about 11.5–27% compared to the conventional MEA only process
Laboratory Analysis of Flow Around Body
No full textU ovom završnom radu prikazani su rezultati laboratorijske analize strujanja zraka oko određenog
objekta, kvadra. Dobivene su vrijednosti odstupanja prikupljenih podataka putem PLC – a i
direktno preko transmitera za Average Pitot i Hot Wire. U radu su istaknute i regresijske krivulje
koje su dobivene na temelju razlike očitanja između PLC – a i transmitera te se mogu koristit
ubuduće za različite normirane brzine vrtnje ventilatora kako bi se došlo do točnih podataka i preko
PLC – a. Provedena su i mjerenja koja omogućuju analizu utjecaja zida na uniformnost strujanja
zraka te mjerenja kojima se opisuje turbulentno područje iza kvadra. Također, u ovom završnom
radu objašnjeni su pojmovi vezani za aerodinamičnost objekata, vrste i dijelovi zračnih tunela,
senzorika koja se primjenjuje prilikom mjerenja te problemi koji se pojavljuju prilikom strujanja
fluida oko određenog tijela.This undergradute thesis presents the results of a laboratory analysis of airflow around a specific
object, a cube. Deviation values were obtained from data collected via PLC and directly through
the Average Pitot and Hot Wire transmitters. The work highlights regression curves derived from
the differences between PLC and transmitter readings, which can be used in the future for various
standardized fan rotation speeds to obtain accurate data through the PLC. Measurements were also
conducted to analyze the influence of a wall on airflow uniformity and to describe the turbulent
region behind the cube. Additionally, this undergraduate thesis explains concepts related to object
aerodynamics, types and components of wind tunnels, the sensing technology used in
measurements, and challenges arising during fluid flow around a particular body
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