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Using exergy and optimization models to improve industrial energy systems towards sustainability
Linköping University, Department of Mechanical Engineering, Energy Systems. Linköping University, The Institute of Technology.
2004 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

With finite natural resources and large energy demands in the world, a sustainable development approach becomes increasingly important in the improvement of energy systems. The concept of sustainability is examined with relation to exergy flows on the earth. The present industrial society is obviously not sustainable. The main aim of this study is to analyze and improve industrial energy systems towards an increased sustainability.

Exergy analysis is used for evaluating energy systems and for guiding efficiency-improvement efforts. An existing optimization method is improved and applied to an energy system in order to maximize its economic feasibility and profitability. Life cycle analysis based on exergy is applied in order to further guide towards sustainable development. This thesis offers tools to better evaluate energy systems with regard to physical resource use, economy and environment. These tools are particularly useful for decision-making in long-term plarming.

The concepts and methods presented are useful in the design and optimization of more sustainable energy systems, particularly in industrial processes. A typical Swedish industry, a pulp and board mill, is examined using an improved optimization method together with the exergy method. The main cause of the low exergy efficiency in the mill is irreversibility of combustion and of heat transfer in the steam generator. The change in the price of electricity has a greater effect on the energy cost than the change in the price of fuel, which means a unified European electricity market has large impact on the Swedish industry. Increasing efficiency of processes usually minimizes environmental damage and maximizes economic benefits. In spite of increasing the exergy loss switching from fossil fuel to bio-fuels can decrease the net CO2 emission as well as the energy cost, and is a step towards increased sustainability. The investments in an oil-bark boiler, evaporation plant and recovery boiler give a good supply of sustainable resources, a reduction of environmental impact, and both energy and economical saving. In addition, with replacing the present evaporation plant with the non-conventional one, even more benefits could be achieved. Still, there are more potential for further improvement in the mill.

Place, publisher, year, edition, pages
Linköping: Linköpings universitet , 2004. , 86 p.
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 868
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:liu:diva-22859Local ID: 2200ISBN: 91-7373-933-2 (print)OAI: oai:DiVA.org:liu-22859DiVA: diva2:243172
Public defence
2004-04-23, Kvalitetstekniks seminarierum, Hus A, Linköpings Universitet, Linköping, 10:15 (Swedish)
Opponent
Available from: 2009-10-07 Created: 2009-10-07 Last updated: 2013-01-08
List of papers
1. On exergy and sustainable development - Part 1: conditions and concepts
Open this publication in new window or tab >>On exergy and sustainable development - Part 1: conditions and concepts
2001 (English)In: Exergy: An International Journal, ISSN 1634-7803, E-ISSN 1164-0235, Vol. 1, no 3, 128-145 p.Article in journal (Refereed) Published
Abstract [en]

The future of life on our planet is a matter of great concern. This paper is based on a vision of sustainable development. It is divided into two parts. The first part introduces conditions and concepts that are of importance for sustainable development. Environmental conditions in terms of causes and effects of emissions, the concept of exergy as a physical measure of difference or contrast and a number of different exergy forms common in nature are presented. Emissions and pollutants are differences in the environment, thus effecting the environment. Exergy is a suitable measure of these differences. The concept of sustainability is examined with relation to exergy flows on the earth. Part 2 of this paper introduces methods based on presented concepts and applies these to real systems. Exergy is applied to emissions to the environment by case studies in order to describe and evaluate its values and limitations as an ecological indicator. Exergy is considered as a useful ecological indicator by reference to the literature in the field.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-86944 (URN)10.1016/S1164-0235(01)00020-6 (DOI)
Available from: 2013-01-08 Created: 2013-01-08 Last updated: 2017-12-06
2. On exergy and sustainable development - Part 2: indicators and methods
Open this publication in new window or tab >>On exergy and sustainable development - Part 2: indicators and methods
2001 (English)In: Exergy: An International Journal, ISSN 1634-7803, E-ISSN 1164-0235, Vol. 1, no 4, 217-233 p.Article in journal (Refereed) Published
Abstract [en]

This second part is the continuation of Wall and Gong [Exergy Internat. J. 1 (3) (2001), in press]. This part is an overview of a number of different methods based on concepts presented in the first part and applies these to real systems. A number of ecological indicators will be presented and the concept of sustainable development will be further clarified. The method of Life Cycle Exergy Analysis will be presented. Exergy will be applied to emissions into the environment by case studies in order to describe and evaluate its values and limitation as an ecological indicator. Exergy is concluded to be a suitable ecological indicator and future research in this area is strongly recommended.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-86945 (URN)10.1016/S1164-0235(01)00030-9 (DOI)
Available from: 2013-01-08 Created: 2013-01-08 Last updated: 2017-12-06
3. Industry and the energy market - optimal choice of measures using the MIND method
Open this publication in new window or tab >>Industry and the energy market - optimal choice of measures using the MIND method
2002 (English)In: CRIS Conference on Power Systems and Communications Infrastructures for the future, 2002, China: CRIS, International Institute for Critical Infrastructures , 2002Conference paper, Published paper (Refereed)
Abstract [en]

No abstract available.

Place, publisher, year, edition, pages
China: CRIS, International Institute for Critical Infrastructures, 2002
Keyword
MIND, Industrial energy systems
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-39960 (URN)51866 (Local ID)51866 (Archive number)51866 (OAI)
Conference
Power Systems and Communication Systems Infrastructures for the Future International Conference (CRIS'2002) September 23-27, 2002, Beijing, China
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2013-02-11
4. Optimization of industrial energy systems by incorporating feedback loops into the MIND method
Open this publication in new window or tab >>Optimization of industrial energy systems by incorporating feedback loops into the MIND method
2003 (English)In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 28, no 15, 1655-1669 p.Article in journal (Refereed) Published
Abstract [en]

The MIND (Method for analysis of INDustrial energy system) method has been developed for multi-period cost optimization of industrial energy systems. Existing industrial processes can be represented at the desired level of accuracy, i.e. one modeling unit may represent a part of the production process or the whole plant. The optimization method includes both energy and material flows. Nonlinear relations, energy conversion efficiencies and investment costs are linearized by mixed-integer linear programming. A flexible time-scale facilitates the performance of long- and short-term analyses. In order to meet the requirements with regard to sustainable development, the recycling of energy and material flows is becoming more common in many industrial processes. The recycling or reuse of energy and material is managed by feedback loops, which are incorporated into the original MIND method to improve the model and reduce the calculation time. The improved MIND/F method (MIND method with feedback loops) model is applied to a pulp and paper mill in Sweden. A comparison between the original MIND method with manual handling of the feedback loops and the MIND/F method gives highly satisfactory results. Cost optimization using the improved MIND method is well within the given accuracy and computer time and manual calculation time are both reduced considerably. The reuse of energy and material resources is not only an economic advantage, but also implies a reduction of the environmental impact.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-46367 (URN)10.1016/S0360-5442(03)00170-1 (DOI)
Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2017-12-13
5. Exergy analysis of a pulp and paper mill
Open this publication in new window or tab >>Exergy analysis of a pulp and paper mill
2005 (English)In: International journal of energy research (Print), ISSN 0363-907X, E-ISSN 1099-114X, Vol. 29, no 1, 79-93 p.Article in journal (Refereed) Published
Abstract [en]

Different energy and exergy concepts and methods are presented and applied to a Swedish pulp and paper mill. Flow diagrams show that the exergy content is mostly much less than the energy content of the flows. The largest exergy losses appear in the boilers. Heating processes are highly exergy inefficient. A limited Life Cycle Exergy Analysis (LCEA) shows that the exergy output amounts to over 3 times the spent exergy as non-sustainable resources. By replacing the present use of non-sustainable resources, mostly fuel oil, the mill could move towards a truly sustainable process.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-29317 (URN)10.1002/er.1041 (DOI)14614 (Local ID)14614 (Archive number)14614 (OAI)
Available from: 2009-10-09 Created: 2009-10-09 Last updated: 2017-12-13
6. Coordination of exergy analysis and the MIND method - applied to a pulp and board mill
Open this publication in new window or tab >>Coordination of exergy analysis and the MIND method - applied to a pulp and board mill
2004 (English)In: International Journal of Exergy, ISSN 1742-8297, E-ISSN 1742-8300, Vol. 1, no 3, 289-302 p.Article in journal (Refereed) Published
Abstract [en]

The MIND (Method for analysis of INDustrial energy systems) method has been developed for cost optimisation of industrial energy systems, mainly with regard to quantities of energy. Exergy analysis reveals losses, efficiencies and possible improvements. These methods can be combined in order to improve industrial energy systems. In this paper, a Swedish pulp and board mill is used as a case study. The efficiencies of the processes in the mill are evaluated using exergy analysis. The most exergy inefficient processes are indicated and some improvements are suggested. This case study shows that it is the boilers and the evaporation plant that are the most inefficient processes, with efficiencies down to 29%. Different investment alternatives for these processes are studied and cost optimisation is achieved using the MIND method. The study shows that the energy costs can be reduced by up to 15 million Euros per year while the exergy efficiency can be improved by up to 14%. The combined approach shows that the energy cost-efficient alternatives are also usually exergy efficient.

Keyword
efficiency; energy; exergy; industrial energy system; optimisation; pulp and paper
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-22918 (URN)10.1504/IJEX.2004.005558 (DOI)2273 (Local ID)2273 (Archive number)2273 (OAI)
Available from: 2009-10-07 Created: 2009-10-07 Last updated: 2017-12-13

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