| 1. |
- Algehed, Jessica, 1971, et al.
(författare)
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Energieffektiv indunstning i framtidens massabruk
- 2001
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Ingår i: Fiberlinjekonferensen 01, Stockholm 2001. - 1404-7098.
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Konferensbidrag (refereegranskat)abstract
- Det arbete som presenteras i denna artikel har gjorts inom KAM-programmets energipotentialprojekt. KAM står för Kretsloppsanpassad massafabrik och är ett MISTRA-finansierat forskningsprogram, vars vision är en kretsloppsanpassad massafabrik som tillverkar högkvalitativa produkter och samtidigt utnyttjar vedråvaran så effektivt som möjligt. Förenklat kan man säga att avsikten med energipotentialprojektet är att finna effektiva energisystem för framtidens massa- och pappersbruk, som är tekniskt och ekonomiskt möjliga.För att spara energi i en fabrik måste processerna i sig göras mer effektiva, vilket naturligtvis sker i och med den ständiga teknikutveckling som pågår, men de måste även värmeintegreras bättre med varandra. Exempel på värmeintegration som redan sker är sekundärvärmesystem där värme från olika processdelar återanvänds och integrerade stripprar, som ”lånar” ånga från indunstningsanläggningen istället för att använda färskånga. Pinchtekniken är ett vanligt hjälpmedel för att finna vilka delar i en fabrik som bör värmeintegreras med varandra och vilket minimalt värme- och kylbehov man har när alla delar av fabriken är integrerade på ”rätt” sätt. Flera tidigare pinchstudier har visat att man i ett sulfatmassabruk uppnår störst ångbesparingar när man värmeintegrerar indunstningen med den övriga processen. Anledningen till detta är att indunstningen är en av de största ånganvändarna och samtidigt en av de mest flexibla processerna i ett sulfatmassabruk. I princip kan indunstningen värmeintegreras med den övriga processen på två sätt, antingen genom att indunstningen till viss del utnyttjar spillvärme från den övriga processen vid relativt låga temperaturer, dvs under 100°C, eller att indunstningen drivs vid så hög temperatur att den delvis kan leverera lågtrycksånga till den övriga processen. Dessa båda sätt att värmeintegrera indunstningen på har studerats vid Institutionen för värmeteknik och maskinlära och i denna artikel sammanfattas resultat från två vetenskapliga artiklar , , som handlar just om spillvärmedriven indunstning och indunstning driven med mellantrycksånga.
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| 2. |
- Algehed, Jessica, 1971
(författare)
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Energy Efficient Evaporation in Future Kraft Pulp Mills
- 2002
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the future, the technical and economic conditions for energy savings in the pulp and paper industry will change. More excess heat will be available in future mills above 80°C than in existing mills, increasing the potential for process integration, and governmental actions for reducing CO2 emissions and the deregulation of electricity markets will change the economic conditions for investments aimed at saving energy. Evaporation plants are some of the largest energy consumers in the pulp and paper industry, but also some of the most flexible unit operations. The objective of this thesis has therefore been to study the possibilities to save energy in future kraft pulp mills by integrating the evaporation plant with the rest of the process. The emphasis has been on quantifying the energy savings possible and understanding how they are influenced by different parameters on several system levels. Conventionally designed evaporation plants as well as evaporation plants that use excess heat and/or deliver low-pressure steam to the steam network have been simulated for different model mills. Using the simulation results, the energy efficiency and economics for the different designs have been compared at a wide range of conditions. The reductions in CO2 emissions have also been calculated. The work presented in this thesis has been performed within a Swedish research program called the Eco-cyclic Pulp Mill. The simulation results show that the live steam demand in the evaporation plant can be lowered by 22-93% in the model mills evaluated if the evaporation plant is process integrated. They also show that the greatest reductions are achieved if the evaporation plant is designed to use both MP steam and excess heat. In general, the results from the economic parameter studies show that the process integrated evaporation designs also are interesting from an economic perspective. They are also favored by a low electricity price (unless condensing power is produced) and a high fuel price, since this increases the benefit of saving fuel. It is further concluded that all process integrated designs reduce CO2 emissions; the size of the reduction, however, depends on how the saved fuel is used and how the marginal electricity production in society is generated.
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| 3. |
- Algehed, Jessica, 1971, et al.
(författare)
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Energy efficient evaporation in future pulp and paper mills
- 2002
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Ingår i: 7th Conference on New Available Technologies, SPCI 2002, Stockholm 2002. - 1404-7098.
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Konferensbidrag (refereegranskat)abstract
- In this paper ways to design energy efficientevaporation plants in future pulp and paper mills arediscussed. There is more than 1 GJ/ADMT excessheat in the model mills studied that can be madeavailable for use in other parts of the mill. If thisheat is used for evaporation and/or if the evaporationplant is designed to use MP steam and deliver LPsteam to the steam network, large amounts of steamcan be saved. It is shown that these savings lead toreductions in CO2 emissions; the largest reductionare achieved if assuming that oil can be saved or ifbiomass fuel is exported from the mill and used toreplace oil elsewhere. It is also shown that theeconomic incentive for redesigning the evaporationplant depends on how the saved live steam is usedand the economic conditions assumed. The largestsavings are obtained if the live steam savings lead todecreased oil consumption. If producing condensingpower or excess bark that can be sold, the savingsare smaller, but in most cases still considerable in size.
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| 4. |
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| 5. |
- Algehed, Jessica, 1971, et al.
(författare)
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Evaporation of black liquor and wastewater using medium-pressure steam : Simulation and economic evaluation of novel designs
- 2003
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Ingår i: ScienceDirect. - 1404-7098. ; 23:4, s. 481-495
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, novel evaporation plant designs that use medium-pressure steam and deliver low-pressure(LP) steam to the steam network as well as conventionally designed plants are simulated and evaluatedfrom a technical and economic point of view. Both evaporation of black liquor only and combinedevaporation of black liquor and wastewater are analyzed.The results show that the novel designs suggested in this work all have large potential to save live steamand that an additional 8 m3 of wastewater/ADMT (air dry metric ton) can be evaporated without increasingthe mill´s total live steam demand. They also indicate that the demand for LP steam in the rest ofthe process is less important for the savings in live steam. The total cost for the novel designs and the relationship between that cost and the cost for conventional designs depend on the economic conditions assumed. If the investment in a more energy efficient evaporation plant is considered from a strategic point of view using an annuity factor of 0.1 and if the cost of thesaved fuel is rather high in comparison to the electricity price, the total cost for the novel designs will have alower total cost than the traditional designs.
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| 6. |
- Algehed, Jessica, 1971, et al.
(författare)
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Modelling energy efficiency and carbon dioxide emissions in energy-intensive industry under stringent CO2 policies: Comparison of top-down and bottom-up approaches and evaluation of usefulness to policy makers
- 2009
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Ingår i: Proceedings of eceee 2009 summer study. - 9789163344541 ; , s. 1181-1191
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Konferensbidrag (refereegranskat)abstract
- The question of how different climate policies will influence carbon dioxide (CO2) emissions in the energy-intensive industry is complex. It is not obvious that increased costs for emitting CO2 will lead to investments in new, low-emission technologies, since the energy-intensive industry is very capital intensive, and reduced CO2 emissions beyond a certain point require large investments and possibly also radical process changes. Traditionally, either top-down or bottom-up models have been used to analyze the influence of specific policies on energy efficiency and CO2 emissions in industry. Bottom-up models describe technologies in detail, but are not realistic in their characterization of corporate decision-making, e.g., how businesses select technologies and make investments, and fail to depict macro-economic equilibrium feedbacks. Top-down models, in contrast, address these deficiencies by representing macro-economic feedbacks and by estimating parameters of technological change from observations of aggregate market responsiveness to cost changes. However, since top-down models lack technological detail, they are weak in assessing the use of new, low-emission technology. Because of these methodological differences, top-down and bottom-up models often make divergent cost predictions, and consequently suggest different policies, for meeting climate targets. This methodological divide has stimulated exploration of hybrid approaches that integrate the technological explicitness of bottom-up models with the micro-economic realism and macro-economic feedbacks of top-down models. To better understand the dynamics and policy responses of industry, such methods and models need to be further developed and applied. In this paper we analyse and compare top-down, bottom-up, and integrated (hybrid) approaches that have been used for evaluating potentials for CO2 emissions reductions and CO2 policy analysis in energy-intensive industry. We also evaluate the usefulness of these approaches and models to policy and decision makers.
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| 7. |
- Algehed, Jessica, 1971, et al.
(författare)
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Opportunities for process integrated evaporation in kraft pulp mills
- 2000
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Ingår i: TAPPI Engineering Conference. ; , s. 841-849
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Konferensbidrag (refereegranskat)abstract
- This paper discusses how medium high temperature excess heat made available through process integration can be used for evaporation of black liquor and different types of wastewater. The amount of medium high temperature excess heat varies considerably in different mills, and apart from a reference mill two other mills are simulated-one that uses a new dryer combined with non-conventional evaporation design and one minimum effluent pulp mill. Several new evaporation plant designs are technically and economically analyzed. The total number of evaporators, amount and temperature of black liquor and wastewater to be evaporated, as well as temperature and amount of excess heat available are varied. The economic value of the total energy savings due to the new evaporation design is shown, and the investment opportunity to make different amounts of excess heat available is stated. This work shows that the total live steam demand for today's and future kraft pulp mills can be reduced by at least 20% with a non-conventional evaporation design. The results also show that there is a relatively large investment opportunity to make excess heat available for evaporation.
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| 8. |
- Berntsson, Thore, 1947, et al.
(författare)
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Towards Sustainabel Oil Refinery - Pre-study for larger co-operation project
- 2008
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In this report, the Chalmers EnergiCentrum (CEC) presents the results of a pre-study commissioned by Preem relating to the effective production of future vehicle fuels.This pre-study was made up of three studies focusing on energy streamlining, the utilisation of waste heat and carbon-dioxide separation and biorefinement relating to the gasification and hydration of vegetable oils. One of the common starting points for these studies was the current situation at the Preem refineries in Göteborg and Lysekil from where the measurement data were obtained and analysed. The report summarises the knowledge situation based on current research in the individual technical fields. The results present some interesting future opportunities for developing the sustainable production of future vehicle fuels. The sections vary, as the areas that have been examined differ and the sections have been written by different people. The reports ends with some joint conclusions and a number of questions which could be included and answered in a more extensive future main study, as part of a developed research partnership between Preem and the Chalmers University of Technology. The preliminary results of this work were analysed with the client at workshops on 1 October and 29 November 2007. The report is written in English combined with an extensive summary in Swedish including a proposal on a future main study. The study was conducted by the Chalmers EnergiCentrum (CEC), in collaboration with a number of researchers in the CEC’s network. They included Thore Berntsson, Jessica Algehed, Erik Hektor and Lennart Persson Elmeroth, all from Heat and Power Technology, Börje Gevert, Chemical and Biological Engineering, Tobias Richards, Forest Products and Chemical Engineering, Filip Johnsson and Anders Lyngfelt, Energy Technology, and Per-Åke Franck and Anders Åsblad, CIT Industriell Energianalys AB. The client, Preem, was represented by Bengt Ahlén, Sören Eriksson, Johan Jervehed, Bertil Karlsson, Gunnar Olsson, Ulf Kuylenstierna, Stefan Nyström, Martin Sjöberg and Thomas Ögren. Tobias Richards was responsible for compiling the report and Bertil Pettersson was the project manager.
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| 9. |
- 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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| 10. |
- Jönsson, Johanna, 1981, et al.
(författare)
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A systematic approach for assessing steam balances for kraft pulp mills-model development and case study
- 2009
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Ingår i: 22nd International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, ECOS 2009; Foz du Iguacu, Parana; Brazil; 30 August 2009 through 3 September 2009. ; , 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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