| 1. |
- Heyne, Stefan, 1979, et al.
(författare)
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Production of synthetic natural gas from biomass - Process integrated drying
- 2009
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Ingår i: 22nd International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems. - 2175-5426. ; , s. 1877-1886
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Konferensbidrag (refereegranskat)abstract
- Opportunities for process integrated feedstock drying in connection with the production of synthetic natural gas (SNG) from wet biomass via indirect gasification are investigated in this study. Drying is a very energy-intensive process step – corresponding to about 10% of the dry fuel lower heating value for woody biomass. Process integrated drying offers opportunities for reducing the external energy supply necessary for drying, thereby improving the overall process efficiency. Simulation models for three drying technology options – air, steam and flue gas drying – have been developed using the flowsheeting software tool ASPEN Plus. The influence of basic operation parameters on the performance of the different drying configurations is investigated using sensitivity analysis. Based on a proposed SNG production process that is built as an extension of a fluidized bed boiler for a combined heat and power plant, the potential for heat integrated drying is assessed using pinch analysis in combination with the developed drying models. The biomass – 100 MWth input for both combustion and gasification, respectively - needs to be dried from 50 to 10 weight-% moisture content prior to combustion/gasification. It is shown that it is not possible to cover all feedstock drying needs for the process by internal heat recovery. Steam drying offers the highest potential for heat integration with the proposed SNG process, making it possible to cover 47.7 % of the necessary total dry fuel supply to both combustion and gasification. However, not all process heat used in the steam dryer can be recovered, increasing the external heat need to the SNG process at a lower temperature level. Nevertheless, substantial savings are possible making use of integrated drying within the SNG production process compared to stand-alone drying.
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| 2. |
- Jönsson, Johanna, 1981, et al.
(författare)
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A systematic approach for assessing potentials for energy efficiency at chemical pulp mills
- 2009
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Ingår i: Proceedings of 22nd Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems. - 2175-5426. ; :Paper 0924, s. 1559-1568
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Konferensbidrag (refereegranskat)abstract
- When estimating aggregated potential for energy efficiency and the introduction of new, efficient, technology solutions within the pulp and paper industry it is important to consider the existing energy system of the individual mills, since the present energy situation at each mill has a significant effect on the potential for future changes. Recognising the need to assess the existing system, one main problem is that detailed steam data is not publicly available or easily accessible, neither on the mill level nor the national level. In the study presented in this paper, a model is proposed for assessing the steam balance of a kraft pulp mill, assuming only a limited amount of public and easily accessible data. The model was developed and validated using detailed data from both model mills and real mills. From the validation of the model it was concluded that the model provides a good estimate of the total steam production and consumption, with an accuracy of +/- 8%, and a fair estimate of the steam use at different pressure levels. The model was also applied in a benchmark study of the Swedish kraft pulp industry. In the benchmark study the potential for increased electricity production was analysed, assuming the steam balance for each mill given by the model. The results showed that all the kraft pulp mills in Sweden could increase their power production substantially by investing purely in new, larger, back-pressure turbines to avoid throttling any steam. If at the same time the mills invest in steam-saving measures, saving LP steam, and a condensing turbine, electricity production could increase even further, making all mills self-sufficient, and most mills even net exporters, of electric power. However, to analyse the potential for steam-saving measures further as well as the introduction of technology solutions other than increased electricity production, such as black liquor gasification, the model needs to be developed further.
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| 3. |
- Svensson, Inger-Lise, 1979-, et al.
(författare)
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Socio-Techincal Aspects of Potential Future Use of Excess Heat from Kraft Pulp Mills
- 2009
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Ingår i: 22nd International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems. ; :Paper 0612, s. 995-1004
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The pulp and paper industry is one of the largest energy users in Sweden and in 2007 2.2 TWh of heat was delivered from pulp mills, mainly to district heating systems. In this study, two market kraft pulp mills and two energycompanies (ECOs) have been interviewed about their views on excess heat, energy efficiency and energy strategies.The interviews have been brought together with results from previous optimization studies concerning kraft pulp millexcess heat by the authors and results from other related work in a socio-technical synthesis that aims to provide amore comprehensive view on the factors that influence the utilization of kraft pulp mill excess heat than achieved inprevious studies. The results show that the kraft pulp mills are more positive towards sales of excess heat than theECOs, which can be related to the fact that the ECOs take a greater risk when entering a heat cooperation. Anotherbarrier to co-operations is the already existing utilities in the ECOs that compete with excess heat for the position asbase load in the district heating systems. Both internal and external use of excess heat can benefit from policymeasures. Other important factors are the view on energy-related investments in the mill, the level of communicationbetween the parties, and the goodwill qualities obtained through energy-efficient solutions.
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