| 1. |
- Lindberg, Carl-Fredrik, et al.
(författare)
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Key performance indicators improve industrial performance
- 2015
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Ingår i: CLEAN, EFFICIENT AND AFFORDABLE ENERGY FOR A SUSTAINABLE FUTURE. - : Elsevier. ; 75, s. 1785-1790
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Konferensbidrag (refereegranskat)abstract
- Key Performance Indicators (KPIs) are important for monitoring the performance in the industry. They can be used to identify poor performance and the improvement potential. KPIs can be defined for individual equipment, sub-processes, and whole plants. Different types of performances can be measured by KPIs, for example energy, raw-material, control & operation, maintenance, etc. Benchmarking KPIs with KPIs from similar equipment and plants is one method of identifying poor performing areas and estimating improvement potential. Actions for performance improvements can then be developed, prioritized and implemented based on the KPIs and the benchmarking results. An alternative to benchmarking, which is described in this paper, is to identify the process signals that are strongest correlated with the KPI and then change these process signals in the direction that improves the KPI. This method has been applied to data from a combined heat and power plant and a suggestion are given on how to improve boiler efficiency. (C) 2015 The Authors. Published by Elsevier Ltd.
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| 2. |
- Han, Song, 1978-, et al.
(författare)
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Influence of drying process on the biomass-based polygeneration system of bioethanol, power and heat
- 2012
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 90:1, s. 32-37
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Tidskriftsartikel (refereegranskat)abstract
- One of the by-products from bioethanol production using woody materials is lignin solids, which can be utilized as feedstock for combined heat and power (CHP) production. In this paper, the influence of integrating a drying process into a biomass-based polygeneration system is studied, where the exhaust flue gas is used to dry the lignin solids instead of direct condensation in the flue gas condenser (FGC). The evaporated water vapor from the lignin solids is mixed with the drying medium for consequent condensation. Thus, the exhaust flue gas after the drying still has enough humidity to produce roughly the same amount of condensation heat as direct condensation in the existing configuration. The influence of a drying process and how it interacts with the FGC in CHP production as a part of the polygeneration system is analyzed and evaluated. If a drying process is integrated with the polygeneration system, overall energy efficiency is only increased by 3.1% for CHP plant, though the power output can be increased by 5.5% compared with the simulated system using only FGC.
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| 3. |
- Hermansson, K., et al.
(författare)
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An Automated Approach to Building and Simulating Dynamic District Heating Networks
- 2018
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Ingår i: IFAC-PapersOnLine. - : Elsevier B.V.. - 2405-8963. ; 51:2, s. 855-860
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Tidskriftsartikel (refereegranskat)abstract
- In Nordic countries, district heating accounts for a large share of the consumers’ heat demand. In Sweden, roughly 50% of the total heat demand is attributed to district heating. Which, over the past few years, is equivalent to around 50 TWh, and imposes a difficult balance between supply and demand for the suppliers of district heating. For large networks the propagation of heat from supplier to end-user can vary several hours. Further complexities of large networks, which can consist of multiple overlapping rings, is that during transient conditions the flow can actually change direction. A dynamic modeling library has been developed in Modelica using OpenModelica for district heating networks. Methods for modeling, handling data, simulating and the visualization of results has been developed using Matlab. The model has been validated using data from Mälarenergi AB, a local provider of district heating in Västerås, Sweden. The model provides to an acceptable degree in predicting the heat propagation and temperature distribution in a localized case study. Adding a higher level of robustness, the model has the capacity to handle bi-directional and reversing flows in complex ring structures. Through this work, the combination of OpenModelica and Matlab, a framework for automating the building and simulation of district heating networks is obtainable. The implications of automating network modeling from computer-aided design drawings allows for a quick robust overview of how the network is working and how prospective additions to the network could impact the end-users. Furthermore, incorporating visual aspects for heat propagation in a network contributes to a higher understanding of complex network structures.
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| 4. |
- Leduc, Sylvain, et al.
(författare)
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Optimal location of lignocellulosic ethanol refineries with polygeneration in Sweden
- 2010
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Ingår i: Energy. - : Elsevier. - 0360-5442 .- 1873-6785. ; 35:6, s. 2709-2716
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Tidskriftsartikel (refereegranskat)abstract
- The integration of ethanol production with combined heat and power plants is considered in this paper. An energy balance process model has been used to generate data for the production of ethanol, electricity, heat and biogas. The geographical position of such plants becomes of importance when using local biomass and delivering transportation fuel and heat. An optimization model has thus been used to determine the optimal locations for such plants in Sweden. The entire energy supply and demand chain from biomass outtake to gas stations filling is included in the optimization. Input parameters have been studied for their influence on both the final ethanol cost and the optimal locations of the plants. The results show that the biomass cost, biomass availability and district heating price are crucial for the positioning of the plant and the ethanol to be competitive against imported ethanol. The optimal location to set up polygeneration plants is demonstrated to be in areas where the biomass cost is competitive and in the vicinity of small to medium size cities. Carbon tax does not influence the ethanol cost, but solicits the production of ethanol in Sweden, and changes thus the geography of the plant locations.
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| 5. |
- Ma, Zhanyu, et al.
(författare)
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Dynamic Prediction of the Heat Demand for Buildings in District Heating Systems
- 2013
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Ingår i: Proceedings of the 5th International Conference on Applied Energy.
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Konferensbidrag (refereegranskat)abstract
- Heat demand is a key parameter for optimizing district heating (DH) systems. A mathematical model employing the Gaussian mixture model (GMM) was developed in order to predict the heat demand in DH systems on the consumer side. Prediction of heat demands needs to consider outdoor temperature and people’s social behaviors. In order to precisely consider the effects of social behaviors, the buildings in DH systems were classified into three types: commercial buildings, office buildings and apartment buildings. The model was trained and validated based on the water flow rate and the temperatures of supply and return water in the DH system. The results showed that the model can predict the heat demand in DH systems with an uncertainty between 4-9%. According to the heat demand predicted by the developed model, the potentials of energy saving in the DH system were analyzed.
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| 6. |
- Ma, Z., et al.
(författare)
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Statistical analysis of energy consumption patterns on the heat demand of buildings in district heating systems
- 2014
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Ingår i: Energy and Buildings. - : Elsevier BV. - 0378-7788 .- 1872-6178. ; 85, s. 664-672
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Tidskriftsartikel (refereegranskat)abstract
- Precise prediction of heat demand is crucial for optimising district heating (DH) systems. Energy consumption patterns (ECPs) represent a key parameter in developing a good mathematical model to predict heat demand. This study quantitatively investigated the impacts of ECPs on heat consumption. Two key factors, namely, time and type of buildings, were used to reflect various ECPs in DH systems, and a Gaussian mixture model (GMM) was developed to examine their impacts on heat consumption. The model was trained and validated using the measured data from a real DH system. Results show that the factor of time does not represent a good reflection of ECP. In contrast, categorising buildings according to their function is an effective way to reflect ECPs. Based on the defined building types, i.e., commercial, apartment and office, the average absolute deviation of the predicted heat load was about 4-8%.
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| 7. |
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| 8. |
- Starfelt, Fredrik, et al.
(författare)
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Case study of energy systems with gas turbine cogeneration technology for an eco-industrial park
- 2008
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Ingår i: International Journal of Energy Research. - : Hindawi Limited. - 0363-907X .- 1099-114X. ; 32:12, s. 1128-1135
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Tidskriftsartikel (refereegranskat)abstract
- Eco-industrial parks (EIP) are clusters of industry corporations that collaborate with reusing waste and energy-efficient use of resources with no or minor impact on the environment. This paper presents a case study that examines the feasibility of using gas turbine technology in one industrial park, located in the Dongguan city of the Guangdong province in China. A model of a gas turbine-based combined heat and power (CHP) plant with a heat recovery steam generator for absorption cooling was developed and simulated. A steam-injected gas turbine has been selected in the system to increase electricity production and to generate steam. The study includes performance analysis of the cogeneration plant in terms of thermal efficiency, cost estimation, and greenhouse gas emission. The gas turbine-based cogeneration system has been compared with a baseline reference case that is defined as if all the energy to the industrial park is supplied from the local electricity grid. The results show that the gas turbine-based cogeneration system can reach a total efficiency of 58% and reduce CO, emissions with 12 700 tons per year. A sensitivity analysis on the costs of the system has also been made based on fuel costs and the interest rate, which shows that the investigated system is economically profitable at natural gas prices below 4.4 RMB m(-3) with fixed electricity prices and at electricity prices above 736 RMB MWh(-1) with fixed natural gas prices. The sensitivity analysis based on the interest rate showed that the proposed system is economically feasible with interest rates up to 16%.
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| 9. |
- Starfelt, Fredrik, et al.
(författare)
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Case Study of Energy Systems with Gas Turbine Cogeneration Technology for an Eco-Industrial Park
- 2007
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Ingår i: 3rd International Green Energy Conference. - 9789185485536 ; , s. 509-515
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Konferensbidrag (refereegranskat)abstract
- Eco-industrial parks (EIP) are clusters of industry corporations that collaborate with reusing waste and energyefficient use of resources with no or minor impact on the environment. This paper presents a case study that examines the feasibility of using gas turbine technology in one industrial park, located in Dongguan city of Guangdong province in China.A model of a gas turbine based combined heat and power (CHP) plant with a heat recovery steam generator (HRSG) for absorption cooling was developed and simulated. A steam-injected gas turbine (STIG) has been selected in the system to increase electricity production while generating steam. The study includes performance analysis of the cogeneration plant in terms of thermal efficiency, cost estimation, and greenhouse gas emission. The gas turbine based cogeneration system has been compared to a baseline reference case that is defined as if all energy to the industrial park is supplied from the local electricity grid. The results show that the gas turbine based cogeneration system can reach a thermal efficiency of 58 % and reduce the CO2 emissions with 12,700 tons per year. A sensitivity analysis on the costs of the system has also been made based on fuel costs and interest rate which shows that the investigated system is economically profitable at natural gas prices below 4.4yuan/m³ with fixed electricity prices and at electricity prices above 736 yuan/kWh with fixed natural gas prices. The sensitivity analysis based on interest rate showed that the proposed system is economically feasible with interest rates up to 16 %.
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| 10. |
- Starfelt, Fredrik
(författare)
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From Combined Heat and Power to Polygeneration
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In order to reach targets on reducing greenhouse gas emissions from fossil resources it is necessary to reduce energy losses in production processes. In polygeneration, several processes are combined to complement each other to avoid sub-optimization of the standalone processes. This thesis addresses polygeneration with focus on Combined Heat and Power (CHP) production integrated with other processes. Biomass-fired CHP plants are commonly dimensioned to have surplus heat production capacity during periods with lower heat demand. At the same time, production of biomass based vehicle fuels and fuel upgrading are heat demanding processes. The opportunity to combine CHP with ethanol production from lignocellulosic feedstock and torrefaction with the aim of replacing fossil fuels are used as cases during the evaluation of polygeneration. Simulation models are used to investigate the performance of CHP integrated with production of ethanol and torrefaction. Measured data from commercial CHP plants have been used to reflect the operation boundaries. The findings show that polygeneration can compete with stand-alone production in both energy and economic performance. Polygeneration offers a wider operating range where reduced minimum load gives increased annual operating time. Therefore, under limited heat demand more renewable electricity production is possible due to increased operating hours and steam extraction from the turbine during part-load operation. Resource availability and fluctuations in fuel price have the largest impact on the profit of polygeneration. Other aspects that have substantial effects on the economy in polygeneration are the electricity spot price and subsidies. Furthermore, it has been proven that the yield of each product in a multiproduct process plant, the size of the plant and the heat demand have a large impact on the economy. Polygeneration turns by-products into buy-products.
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