| 7941. |
- Iplik, Esin
(författare)
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Energy savings for petroleum processing : Using mathematical models, optimal control and diagnostics
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Petroleum products are widely used as an energy supply, and the total production capacity of petroleum refineries is quite high. In this thesis, an energy intensive refinery process, hydroprocessing, is selected and evaluated in terms of its energy loss contributors. Digital solutions are discussed and demonstrated to reduce losses. Both hydrotreatment and hydrocracking processes are included in the evaluation since both require elevated temperatures due to the relevant reactions. While the former is the removal of undesired atoms, the latter is the production of short chain hydrocarbons from heavy oil. Both these processes contribute to cleaner fuel production.When these processes are carried out in fixed bed reactors, the catalyst ages over time, slowing the reactions. Understanding the changes in system dynamics enables the control system to calculate the necessary temperature adjustments to facilitate stable product quality. The usual response is increasing the temperature, which adds to the heat load. If reaction rates are known, the temperature increase can be kept to a minimum. Obtaining real-time feed quality information can aid flexible feed processing refineries intensely. With real-time feed characterization, it is possible to use a feed forward model predictive control system to optimize reactor temperatures. Therefore, for varying crude oil quality, the control system can estimate the minimum temperature requirements for the product to be in the desired quality interval. Additional notice should be given to the temperature sensors as they supply data to the suggested control architecture. Wrong measurements threaten the optimality of the estimated control response. Faulty sensors should be detected and replaced to minimize the risk and collect correct data.Observations made in this thesis show the possible energy gain for hydroprocessing by understanding the aging catalyst, soft sensor installation, feed forward model predictive control, and sensor fault detection. Hydroprocessing is a relevant topic for biorefineries. Although the demonstrations in this work are only for petroleum refineries, the suggested methods can be used in biorefineries as well as integrated co-processing petroleum and biorefineries.
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| 7942. |
- Iplik, Esin, et al.
(författare)
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Feasibility study on the use of electrolyzers for short term energystorage
- 2021
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Ingår i: The First SIMS EUROSIM Conference on Modelling and Simulation, SIMS EUROSIM 2021, and 62nd International Conference of Scandinavian Simulation Society. - : Linköping University Electronic Press. - 9789179292195 ; , s. 234-240
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Konferensbidrag (refereegranskat)abstract
- Electricity grid flexibility is vital for renewable energy to be used effectively. Power-to-gas technologies are investigated to connect electricity grid to gas grid and to tackle capacity challenges. Grid management expenses consist of redispatch and feed-in management. These management procedures, next to being costly, cause a significantenergy loss. Proton-exchange membrane electrolyzer installations were studied to reduce these expenses and recover energy. The change in the levelized cost of hydrogen production with varying electrolyzer capacities was presented. The sensitivity of the levelized cost and net presentvalue with respect to installation costs, maintenance costs, and electricity prices were investigated. While the electricity prices have the most significant effect on the levelized cost of hydrogen production, the net present value was affected considerably by the hydrogen selling price. Possible energy savings were calculated between 2 – 23 GWh for 2, 5, 10, 20 MW installations. The annual gridmanagement expense savings were in the range of 0.2– 2.3 million Euros, increasing with the increasing electrolyzer capacity.
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| 7943. |
- Iplik, Esin, et al.
(författare)
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Hydrocracking: A Perspective towards Digitalization
- 2020
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Ingår i: Sustainability. - : MDPI AG. - 2071-1050. ; 12:17
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Tidskriftsartikel (refereegranskat)abstract
- In a world of fast technological advancements, it is increasingly important to see how hydrocracking applications can benefit from and adapt to digitalization. A review of hydrocracking processes from the perspective of modeling and characterization methods is presented next to an investigation on digitalization trends. Both physics-based and data-based models are discussed according to their scope of use, needs, and capabilities based on open literature. Discrete and continuous lumping, structure-oriented lumping, and single event micro-kinetic models are reported as well as artificial neural networks, convolutional neural networks, and surrogate models. Infrared, near-infrared, ultra-violet and Raman spectroscopic methods are given with their examples for the characterization of feed or product streams of hydrocracking processes regarding boiling point curve, API, SARA, sulfur, nitrogen and metal content. The critical points to consider while modeling the system and the soft sensor are reported as well as the problems to be addressed. Optimization, control, and diagnostics applications are presented together with suggested future directions of interdisciplinary studies. The links required between the models, soft sensors, optimization, control, and diagnostics are suggested to achieve the automation goals and, therefore, a sustainable operation.
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| 7944. |
- Iplik, Esin, et al.
(författare)
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Parameter estimation and sensitivity analysis for a diesel hydro-processing model
- 2021
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Ingår i: Computer Aided Chemical Engineering. - : Elsevier B.V.. ; 50, s. 573-578
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Tidskriftsartikel (refereegranskat)abstract
- Model-based approaches are essential for the operation, optimization, and control of applications in the process industry. Different structures are often investigated to build representative and robust models, and a set of parameters with the same attributes are required to utilize them effectively. Parameter estimation gets arduous with the increasing complexity of the process, the model, and the size of the parameter space. In this work, a parameter-estimation problem based on a steady-state model of diesel hydrodesulfurization is investigated using gradient-based and gradient-free optimizers. The optimal parameter sets obtained are then assessed in terms of performance and computational time for the different optimizers. Furthermore, the sensitivity of the various parameters is also investigated. Due to the catalytic reactions in this process, some parameters have to be updated depending on the catalyst activity. In addition to the initial estimation, the updated parameters are also studied, and instead of a time-based one, a tolerance-based recalculation schedule is suggested. Finally, the robustness of the final model is analyzed by giving different operating conditions and feed characteristics. The adaptive parameter approach proved better data fitting capabilities by improving the coefficient of determination for temperature predictions.
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| 7945. |
- Iplik, Esin, et al.
(författare)
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Sensor fault detection with Bayesian networks
- 2020
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Ingår i: Proceedings of The 61st SIMS Conference on Simulation and Modelling, SIMS 2020. - : Linköping University Electronic Press. ; , s. 373-378
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Konferensbidrag (refereegranskat)abstract
- Several sensors are installed in the majority of chemical reactors and storage tanks to monitor temperature profiles for safety and decision-making processes such as heat demand or flow rate calculations. These sensors fail occasionally and generate erroneous measurement data that need to be detected and excluded from the calculations. However, due to the high number of process variables displayed in the chemical plants, this task is not trivial. In this work, a Bayesian network approach to detect faulty temperature sensors is proposed. By comparing the sensor measurements with each other, the faulty sensor is detected. A modular approach is preferred, and networks are created for 10 K temperature intervals to increase flexibility and sensitivity. Created networks can be adjusted for the operating temperature ranges; hence, they can be used for any catalyst and entire life cycle. The developed method is demonstrated on an industrial scale hydrocracker unit with 92 sensor couples installed in a series of reactors. From the investigated sensors, 16 of them showed a greater difference than the 2 K threshold chosen for the fault. In addition to that, 13 sensors showed an increasing temperature difference that may lead to a fault. Two scenarios were created to calculate the energy loss due to a faulty measurement, and a 5.5 K offset error was found to cause a 5.79 TJ energy loss every year for a small scale hydrocracker.
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| 7946. |
- Iqbal, Zahid, et al.
(författare)
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Analyzing the Efficiency of Sporadic Reservations on Ethernet with FTT-SE
- 2017
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Ingår i: International Conference on Emerging Technologies And Factory Automation ETFA'17. - 9781509065059
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Konferensbidrag (refereegranskat)abstract
- Ethernet is a promising candidate for networking real-time embedded systems such as automobiles, and it is already used in several embedded scopes, such as airplanes and trains. Moreover, its higher bandwidth enables applications made of dispersed embedded systems that exchange large amounts of data through the so-called Internet-of-Things, such as wide-area video sensing. In this realm, network reservations are an important design element that favor composability in the time domain thereby supporting the design of complex systems. However, reservations may impact negatively on the network bandwidth efficiency due to over-specification, particularly when they are designed to meet worst-case delay constraints. In this work, we use a specific Ethernet protocol that provides real-time reservations, namely FTT-SE, and we assess through extensive simulations the efficiency of a worst-case network delay analysis for sporadic reservations associated to asynchronous messages. Essentially, we compare the analytical worst-case delay with the one observed in the simulations using two data sets comprising up to 20000 and 100000 message sets, respectively, and we change the system configuration, namely properties of the message sets and network and protocol configuration parameters. We find that the analysis is accurate, i.e. matches observations, for a significant percentage of messages in the message sets (up to 60% on average). Conversely, we found that a small percentage of message sets (below 6%) generated rather pessimistic analytic estimates exceeding the observations by 6 times, thus with a negative impact on efficiency. The results we present in the paper, particularly their distributions, inform system designers of how to tune their designs to improve network bandwidth efficiency under strict timing constraints.
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| 7947. |
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| 7948. |
- Iqbal, Zahid, et al.
(författare)
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Implementing Hierarchical Scheduling on COTS Ethernet Switches Using a Master/Slave Approach
- 2012
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Ingår i: 7th IEEE International Symposium on Industrial Embedded Systems (SIES'12), Conference proceedings. - 9781467326834 - 9781467326858 ; , s. 76-84
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Konferensbidrag (refereegranskat)abstract
- Hierarchical scheduling is instrumental to efficiently deploy component-based designs and achieve composability. It allows partitioning resources into multiple levels, hiding the complexity within each partition behind its respective interface. In this paper we focus on the network resource, particularly on Ethernet using ordinary COTS switches, and we show how hierarchical scheduling can be efficiently deployed using a master/slave approach that enforces the temporal properties of the partitions. We use the FTT-SE protocol for being open source and a bandwidth efficient master/slave alternative currently available for real-time communication over Ethernet. We present a response-time analysis for the traffic submitted within each partition and we validate it using experimental results obtained from a prototype implementation. In particular, the results highlight the strong partitioning capabilities of our approach, with full temporal isolation across partitions in different branches of the hierarchy.
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| 7949. |
- Iqbal, Zahid, et al.
(författare)
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Implementing Virtual Channels in Ethernet using Hierarchical Sporadic Servers
- 2013
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Ingår i: Proc <em>International Workshop on Real-Time Networks</em>. - Paris, France.
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Konferensbidrag (refereegranskat)abstract
- Composability is an important property to build complex applications. One important technique to achieve composability, particularly in the time domain, is multi-level hierarchical server-based design. However, composability must not only be supported among components sharing computing resources but also in their interactions. In this paper we implement hierarchical server-based traffic scheduling within the Flexible Time-Triggered Switched Ethernet (FTT-SE) protocol. The novelty in this work is the use of hierarchical sporadic servers in such setting. We report an efficient usage of the network bandwidth, short reponse times and the temporal isolation across servers.
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| 7950. |
- Irisdotter Aldenmyr, Sara, et al.
(författare)
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Worries and possibilities in active citizenship : Three Swedish educational contexts
- 2012
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Ingår i: Education, Citizenship and Social Justice. - : Sage Publications. - 1746-1979 .- 1746-1987. ; 7:3, s. 255-270
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Tidskriftsartikel (refereegranskat)abstract
- This article examines how the concept of active citizenship has been given a neo-liberal character by examining practice in three different educational contexts in Sweden. The concept of active citizenship has become influential in educational policy and practice throughout the European Union. The aim of this article is to highlight concerns at how this concept has come to be re-shaped by neo-liberal principles in Swedish education. The analysis highlights three themes, based on voice, ethical awareness and complexity and mutuality of lived experience, and argues that they provide the basis for a shift away from the present neo-liberal colouring of the concept.
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