| 1. |
- Björkqvist, Olof, 1962-, et al.
(författare)
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Concepts of Steam Recovery from LC-Refining by Increase Temperature
- 2009
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Ingår i: Proceedings - 2009 International Mechanical Pulping Conference, IMPC 2009. ; , s. 190-194
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Konferensbidrag (refereegranskat)abstract
- In a mechanical pulping process, (TMP) wood is refined to pulp in a process with very high wood utilization. However, the power demand in the process is high. Thus efficient energy recovery, especially steam recov-ery, is very important. In high consistency (HC) refining the pulp wood is refined at high temperature (140°C) and pressure. The high temperature makes it possible to recover process heat with usable steam properties. One strategy to decrease the power consumption is to split the refining into two stages, one HC-stage and one low consistency (LC) refining stage. This kind of sys-tem is quite common today. One drawback with LC-refining is that it operates at a low temperature normally below 100°C. Hence, the steam recovery potential from conventional LC-refining is limited. In this project, we analyse three concepts of steam re-covery in LC-refining by increasing the temperature in the LC-stage. Two base cases: Conventional HC refin-ing only and conventional HC/LC refining is compared with three steam recovery cases: Pulp/Pulp heat ex-changing, Screw Press Dewatering combined with proc-ess water re-circulation and finally Pulp/Water Heat Exchanging. The study shows that it is possible to recover steam from the LC-stage and, hence, increase the energy effi-ciency of a combined HC/LC refining system. The screw press case has the highest steam recovery poten-tial of the HC/LC configurations. An initial economic estimate indicates that steam recovery in LC-refining is profitable compared to a conventional HC/LC-configuration.
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| 2. |
- Björkqvist, Olof, 1962-, et al.
(författare)
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Energiåtervinning vid LC-raffinering – Förstudie
- 2008
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Ökade energikostnader och råvarupriser innebär att effektiv energianvändning blir enviktig faktor för att skapa långsiktig konkurrenskraft och utvecklingsförmåga för massaochpappersindustrin. I detta projekt analyseras möjligheten att öka ångåtervinningenfrån en mekanisk massaprocess där raffinering vid hög massakoncentration (HCraffinering)kombineras med raffinering vid låg massakoncentration (LC-raffinering).Vid HC-raffinering finns sedan många år väl utvecklad teknik för att återvinna ånga.Vid konventionell LC-raffinering är det inte möjligt att återvinna ånga eftersom temperaturnivåernaär för låga, lägre än 100°C. Genom att värmeväxla producerad massa ellerpressat från processen kan man öka temperaturen i LC-steget så att det blir möjligt attåtervinna processånga med användbara ångdata, i detta fall 2,7 bar och 130°C.I projektet har tre alternativa konfigurationer för ångåtervinning analyserats(A) Ångåtervinning i kombination med massa/massa värmeväxling (B) Ångåtervinningi kombination med en trycksatt skruvpress och (C) Ångåtervinning i kombination medmassa/vatten värmeväxling.En inledande lönsamhetsberäkning visar att ångåtervinning från LC-steget kan ha enmycket god lönsamhet. Fall B, ångåtervinning i kombination med trycksatt skruvpressvisar bäst potential för fortsatta studier. Det beror på att värmeåtervinningen sker genominblandning av pressat i spädvattnet och värmeväxling av vatten med en konventionellvärmeväxlare. Det innebär att de tekniska riskerna i detta alternativ är låga.Utvecklingen av de värmeväxlare som ingår i fallen A och B och som kan hantera massamed 5% massakoncentration innebär en stor teknisk utmaning och associerad risk.Det finns idag inga sådana växlare på marknaden och det är osäkert om man kan konstrueraen växlare som kan hantera massa med hög viskositet och som har tillräckligthög temperaturverkningsgrad.Projektet har uppfyllt målet att visa att det teoretiskt är energitekniskt möjligt att modifieraen LC-process så att ånga kan återvinnas även från detta steg. Detta innebär enförbättring av den konventionella LC-processens energieffektivitet. Projektets resultatkan vara ett underlag för beslut om fortsatt forskning inom området energieffektiv LCraffinering.
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| 3. |
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| 4. |
- Björkqvist, Olof, 1962
(författare)
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Perspectives on Demand Side Energy Efficiency
- 1996
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This work treats recommendations based on energy systems engineering. The focus is on what can be learned by different methods about the roles that demand-side energy efficiency should play in the energy system. In the first part of the thesis, two case studies of local energy planning demonstrate the role of demand-side energy efficiency: energy systems engineering suggests a design in which energy efficiency improvements are aligned with the whole technical energy system. One result of the case studies is that the energy consumers invest in fewer energy efficiency measures than recommended by the methodologies applied. This indicates that there are important aspects of demand-side energy efficiency that are ignored by the methodologies used. In this work, the cause of the difference between the recommended and observed investments is addressed by an investigation of the customer's transaction cost for the energy efficiency investment. The second part is an application of the viable system model and focuses on the role of energy efficiency activities at a public energy utility. A case study demonstrates that most energy efficiency activities were run to support energy sales and, hence, were totally entwined with the traditional business. This role observed is compared with that suggested by the demand-side management methodology. The comparison shows that demand-side management is not capable of handling important aspects of interrelations between energy efficiency activities and energy sales. The work provides a language for further discussion of the role of energy efficiency activities at energy utilities.
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| 5. |
- Gebremedhin, Alemayehu, 1962-
(författare)
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The impact of a widened energy system boundary on cost effectiveness
- 2000
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This study describes the impact of widened system boundaries in the choice of heat generating plants, the total cost of the defined energy system and the use of combined heat and power (CHP) production plants. The economic and environmental benefits of co operation between public utilities and industries and the importance of enlarged system boundaries are shown in the different case-studies.The analysis was based on computer modelling of municipal and industrial energy systems. A user-friendly graphical interface program based on the linear programming model, MODEST, was developed as part of this study. The majority of the case-studies presented in this thesis were then performed with this application program.The various case-studies clearly indicate the cost reduction potential of co-operation. Both utilities and heat supplying industries benefit from this co-operation concerning heat supply. The cost saving potentials change from one case to another and depend on several factors.New plants within a sub-system appear to be attractive when this system is connected with other sub-systems within the extended system boundaries. In general, we can say that an extended system boundary leads normally to reduced total costs, more rational utilisation of plants, increased heat and electricity generation through the CHP plant and declining use of fossil fuels.The net present value of the maximum allowable investment cost for district-heating pipeline connections is roughly estimated when the cost for connection is not given or known. This cost can be used as a guideline to indicate whether connections should be considered or not.
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| 6. |
- Große, Christine, 1974-, et al.
(författare)
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Collaboration and Decision-making in Response Planning for Power Shortages : The Swedish Policy
- 2017
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Electricity is a key resource for the majority of societal functions and constitutes an important sector in the critical infrastructure of modern societies. Disturbances in power supply can have cascading effects on interdependent public sectors and ordinary citizens. However, it seems nearly impossible to completely prevent the occurrence of power shortages. Strategies to address temporary power losses are therefore essential. This paper aims to increase the understanding of national policies to manage the early consequences of power outages. Therefore, we critically review the Swedish national policy called Styrel as part of Swedish Crisis Management System. In the scientific literature, there are few examples similar to Styrel for handling emergencies in the electricity system. Particularly, we seek to discover related risks and benefits, conditions and constraints, as well as effects for specific stakeholders. We argue that the approach cannot yet be considered as fully developed. Three areas requiring improvement are identified. First, the scope and terms of the process must be specified. Second, (better) quality management seems necessary. Third, people responsible for identifying and prioritizing power consumers critical to local society need better decision aid. Improvements could facilitate risk-communication and collaboration among actors as well as decision-making and organisational learning.
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| 7. |
- Große, Christine, Fil.Dr, 1974-, et al.
(författare)
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Information-flawing Filters in Critical Infrastructure Protection : The deficient Information Basis in a Swedish Approach
- 2023
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Ingår i: International Journal of Critical Infrastructures. - 1475-3219 .- 1741-8038. ; 19:1
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Tidskriftsartikel (refereegranskat)abstract
- Various societal functions, such as healthcare, freight transports, water supplies and electricity, ensure the daily life, endurance and progress of modern societies. The protection of such critical functions requires comprehensive information processing. Based on evidence from documents on the Swedish planning process STYREL and interviews with entrusted decisionmakers at county administrative boards, municipalities and power grid operators, this study aims to crystallise information pathways and flaws to highlight information filtration and alteration. Analyses of the material reveal a set of information-flawing filters, such as information withholding or loss when sharing, information scarcity in criticality assessments and ad-hoc information creation due to scarcity. Because of these filters, the Swedish process causes an altering of information that affects the quality of decisions and the emergency response plan that relies on them. Thus, this study indicates deficiencies that relate to information sharing, information security and decision-making that pose risks to citizens and businesses.
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| 8. |
- Große, Christine, 1974-
(författare)
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Strategic Objectives in Complex Planning Environments : Insights from a Swedish Case for Critical Infrastructure Protection
- 2018
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Large-scale and long-term planning imposes extensive requirements on governance efforts regardless of whether it involves public organisations, private organisations, or both. The proportions of such planning entangle many actors and stakeholders as system components within and around a complex system. These system components and conditions in a complex planning environment introduce a diverse variety of strategic objectives into the planning. This study investigates how strategic objectives can affect the governance of complex planning systems, particularly in the context of national critical infrastructure protection. For this purpose, this thesis concentrates on a national planning procedure, STYREL, which Sweden has recently implemented for the case of power shortages. This case involves various actors from the national, regional and local levels who act on behalf of both public and private organisations in a planning process with four-year intervals, and it thus constitutes a relevant subject for this study. The investigation entailed the collection of evidence from documents and interviews. First, publicly available Swedish documents regarding the case provided an understanding of the planning. Second, interviews with decision-makers who are entrusted with this planning at municipalities and county administrative boards as well as with a few planners from power grid providers offered a deeper comprehension of both the proceedings in practice and the strategic objectives involved in this complex system for planning of critical infrastructure protection. Particularly, the findings resulted in several conceptual models that demonstrate these understandings in more detail. A soft system model visualises the problem situation and contains several elements, such as the system components, interrelations and conditions. Moreover, a multi-level planning model specifies sources of uncertainty in the planning and decision-making process that are associated with an insufficient alignment of strategic objectives in the STYREL case. These decompositions of the Swedish planning environment – both horizontal and vertical – further enabled this study to identify significant parameters of the systemic conditions and strategic objectives involved in such complex planning environments that challenge their governance. The findings of this study suggest that the Swedish process is not yet fully developed. The investigation particularly indicates that a better alignment of strategic objectives is necessary to ensure a selection of adequate goals and means that advances the future usability of the produced plan, which in turn would legitimate and strengthen this complex planning process for critical infrastructure protection.
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| 9. |
- Große, Christine, Fil.Lic, 1974-
(författare)
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Towards Systemic Governance of Critical Infrastructure Protection : State and Relevance of a Swedish Case
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The protection of infrastructure that is critical to society’s functionality, survival and progression has gained significance for both national security and research because of its large-scale and interdependent nature. Critical infrastructure can be viewed as a complex, socio-technical system-of-systems that imposes extensive requirements on governance efforts to foster critical infrastructure protection (CIP), regardless of whether it involves public organisations, private organisations or both.This dissertation investigates how systemic thinking can develop understandings of CIP and its governance. For this purpose, the dissertation presents research that was conducted in the context of an unexplored Swedish governance approach for CIP against power shortages.The dissertation consists of a three-part thesis and six peer-reviewed publications.Part A of this thesis presents the results of a substantial review of scientific literature on the concepts of systems, infrastructure and governance. Because of their recursive nature, the concepts encounter a common challenge in characterising their key elements, structures and processes. The multi-level character of CIP provokes governance to systemically address the behaviours of adaption, emergence and entropy which the complex system exhibits. Apart from contributing nuanced knowledge of systems, infrastructure and governance, Part A provides a novel frame of reference for research in the area in the form of a kaleidoscope for integrative system analysis – KISA.Part B presents the key results of a case study on the Swedish Styrel approach. The investigation is based on an examination of documents that relate to the case, interviews with 66 responsible experts and a survey among all 21 County Administrative Boards and 10 power grid operators that are responsible for stabilising the power grid during disturbances. The contri¬bution of Part B is threefold. First, it originates an extensive representation of an unexplored case of CIP governance. Second, it offers a new comprehen¬sion of practical challenges in CIP governance due to the complex nature of the system and the entangled processes. Third, it provides empirical evidence that indicates areas for development of CIP governance practices.Part C presents the results of the synthesis of theoretical and practical findings. It coalesces perspectives of critical infrastructure and system protection to elaborate on the concept of systemic governance. Fundamentally, systemic governance of CIP integrates the nexus of governance, management and leadership to address challenges regarding key properties of complex systems: entropy, emergence and adaption. Part C defines the theoretical contribution of this dissertation, namely the concept of systemic governance of CIP.
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| 10. |
- Hedlund, Alexander, et al.
(författare)
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A simulation-based method for evaluation of energy system cooperation between pulp and paper mills and a district heating system : A case study
- 2017
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Ingår i: 19 World academy of science, engineering and technology conference proceedings. ; , s. 1158-1164
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Konferensbidrag (refereegranskat)abstract
- A step towards reducing greenhouse gases and energy consumption is to collaborate with the energy system between several industries. This work is based on a case study on integration of pulp and paper mills with a district heating system in Sundsvall, Sweden. Present research shows that it is possible to make a significant reduction in the electricity demand in the mechanical pulping process. However, the profitability of the efficiency measures could be an issue, as the excess steam recovered from the refiners decreases with the electricity consumption. A consequence will be that the fuel demand for steam production will increase. If the fuel price is similar to the electricity price it would reduce the profit of such a project. If the paper mill can be integrated with a district heating system, it is possible to upgrade excess heat from a nearby kraft pulp mill to process steam via the district heating system in order to avoid the additional fuel need. The concept is investigated by using a simulation model describing both the mass and energy balance as well as the operating margin. Three scenarios were analyzed: reference, electricity reduction and energy substitution. The simulation show that the total input to the system is lowest in the Energy substitution scenario. Additionally, in the Energy substitution scenario the steam from the incineration boiler covers not only the steam shortage but also a part of the steam produced using the biofuel boiler, the cooling tower connected to the incineration boiler is no longer needed and the excess heat can cover the whole district heating load during the whole year. The study shows a substantial economic advantage if all stakeholders act together as one system. However, costs and benefits are unequally shared between the actors. This means that there is a need for new business models in order to share the system costs and benefits.
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