| 21. |
- Axelsson, Erik Marcus Kristian, 1974, et al.
(författare)
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Heat integration opportunities in average Scandinavian kraft pulp mills: Pinch analyses of model mills
- 2006
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Ingår i: Nordic Pulp and Paper Research Journal. ; 21:4, s. 466-475
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Tidskriftsartikel (refereegranskat)abstract
- Within the FRAM programme, two models of average Scandinavian mills producing bleached market pulp have been analysed from an energy perspective. The aim was to explore the opportunities for heat integration in order to create a steam surplus. The steam surplus gives opportunities for increased power generation or lignin extraction. The technical and economic consequences of using the steam surplus in this way are explored in a continuation of this project.Two different approaches for creating a steam surplus havebeen investigated: 1) conventional measures and 2) processintegrated evaporation (PIvap). The former approach includes improved heat integration and new equipment. The latter approach means that excess heat from the mill is used for evaporation to partly replace live steam.The two model mills created within FRAM both produce 1000 ADt/d softwood pulp. The mills differ in the level of waterusage, since it is expected that the amount of excess heat for PIvap will increase with decreasing water usage.By investing 11 M€ in conventional measures it is possible to create a steam surplus of 53 MW (about 26% of the total consumption), independent of the level of water usage. For the PIvap approach, the level of water usage matters, since there is more excess heat for PIvap in the mill with lower water usage.As a result, the total steam surplus with the PIvap approach differs in the two mills: up to 52 and 56 MW, respectively. Hence, the steam savings for the PIvap approach are similar to those in the approach with conventional measures; and so are the investments needed (10-12 M€). Even though the two approachesgive approximately the same savings with the same investment, the PIvap approach might be easier to implement in an existing mill.
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| 22. |
- Axelsson, Erik Marcus Kristian, 1974, et al.
(författare)
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Increased capacity in kraft pulp mills: Lignin separation and reduced steam demand compared with recovery boiler upgrade
- 2006
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Ingår i: Nordic Pulp and Paper Research Journal. - 2000-0669 .- 0283-2631. ; 21:4, s. 485-492
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Tidskriftsartikel (refereegranskat)abstract
- For increased production in pulp mills, the recoveryboiler is often a bottleneck. Two different approaches todebottleneck the recovery boiler have been investigated in twomodel mills that represent typical Scandinavian pulp mills. As areference approach, the recovery boiler was upgraded. Inconnection with this, the turbine system was also upgraded toenable increased electricity production. As an alternative to thisconventional approach, the load of the boiler was kept constantby extracting lignin from the black liquor in proportion to theproduction increase. To keep the steam balance, the specificsteam consumption at the mill was reduced through steamsavingmeasures to such an extent that the amount of steamproduced from burning the lignin-lean black liquor was sufficient.Consequently, the extracted lignin was not needed in-houseand could be sold as a biofuel. The net profit of implementinglignin separation was calculated for different conditions. Theresult was that, depending on the conditions, the lignin pricehad to be 2-17 /MWh for lignin separation to be equallyprofitable as boiler upgrade. With an assumed lignin price ofabout 15 /MWh, the conclusion is that lignin separationshould be an economically attractive alternative for debottleneckingthe recovery boiler. With a high power price and along-term investment strategy, however, upgrading the recoveryboiler and the turbine system can be more profitable.
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| 23. |
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| 24. |
- Axelsson, Erik Marcus Kristian, 1974, et al.
(författare)
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Opportunities for Process Integrated Evaporation in a Eucalyptus Pulp Mill and Comparison with a Softwood Mill Study
- 2007
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Ingår i: Conference PRES 07, Ischia Island, Italy. ; , s. 727-732
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Konferensbidrag (refereegranskat)abstract
- Significant energy savings can be made in the pulp and paper industry by implementing process-integrated evaporation (PIvap). The concept of PIvap has been evaluated for a Eucalyptus mill producing bleached kraft market pulp in Portugal and the results were compared to the ones from an earlier model mill study of a soft wood mill. In the eucalyptus mill there were, theoretically, 0.86 GJ/ADt of excess heat suitable for a PIvap besides the 2.6 GJ/ADt of pinch violations. The pinch violations could be transferred to excess heat, but some pinch violations were cost effective to solve. A suggestion where 1.1 GJ/ADt of pinch violations are solved and 1.6 GJ/ADt of excess heat are extracted is presented. If the excess heat is used in a 7 effect PIvap with integrated stripper and increased dry solids content, steam savings of 2.7 GJ/ADt could be made in the evaporation plant. Together with the pinch violations and opportunities for improved soot blowing, the total steam savings from the suggested measures were 4.5 GJ/ADt or 35%. The amount of steam savings and associated costs were similar to the ones in the soft-wood model-mill. Hence, no significant differences could be found for the opportunities to implement PIvap in the hardwood mill compared to in the soft wood mill. The existence of a pre-evaporation plant, however, showed to hinder introduction of PIvap, since a pre-evaporation plant uses excess heat, and uses it ineffectively compared to a PIvap. Hence, the pre-evaporation has been removed in the suggestion for integration presented here.
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| 25. |
- Axelsson, Erik Marcus Kristian, 1974, et al.
(författare)
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Opportunities for process-integrated evaporation in a hardwood pulp mill and comparison with a softwood model mill study
- 2008
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Ingår i: Applied Thermal Engineering. - : Elsevier BV. - 1359-4311. ; 28:16, s. 2100-2107
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Tidskriftsartikel (refereegranskat)abstract
- Significant energy savings can be made in the pulp and paper industry by implementing process-integrated evaporation (PIvap). The aim of this paper was to evaluate the concept of PIvap for a existing hardwood mill producing kraft pulp and compare the results with the ones from an earlier study of a softwood model mill. Using pinch tools, we found a solution where 1.3 GJ/ADt of pinch violations are solved and 1.1 GJ/ADt of excess heat is extracted. If the excess heat is used in an efficient PIvap, steam savings of 2.7 GJ/ADt could be made in the evaporation plant. Together with the pinch violations and improved soot blowing, the total steam savings were 4.6 GJ/ADt or 36% for an investment cost of 6.6 M€. Compared with the softwood model mill, the configuration of the hardwood mill offered about the same savings with 2.7 M€ lower investment cost, making PIvap more interesting in the hardwood mill. As an alternative to implementing PIvap, more pinch violations can be solved. The PIvap approach gives more steam savings to approximately the same specific cost.
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| 26. |
- Axelsson, Erik Marcus Kristian, 1974, et al.
(författare)
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Pinch analysis of a model mill: Economic and environmental gains from thermal process-integration in a state-of-the-art magazine paper mill
- 2005
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Ingår i: Nordic Pulp and Paper Research Journal. ; 20:3, s. 308-315
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Tidskriftsartikel (refereegranskat)abstract
- A model of a modern magazine paper mill has been investigated from an energy perspective. The mills refining process has a power demand of 100 MW (3050 kWh/ADt pulp), and 86 MW of this is recovered as steam. Since the steam demand of the mill is low, there is a steam surplus of 21.5 MW. The steam surplus could be increased by 41 % through thermal process-integration. Simultaneously the cooling demand decreased by 13.2 MW or 49 %, resulting in reduced cooling costs and decreased thermal pollution. The financial evaluation, for which a grass-root situation was assumed, shows promising economy if the mill can sell the surplus heat (e.g. to a district heating system): the marginal payback period for increasing the steam surplus would be less than a year, even with low energy prices. If the surplus steam has to be used on site, power generation in a condensing steam turbine is an option. The financials for increasing the power generation are very dependent on the power price, but with current Swedish power prices the marginal payback period would be 3 to 4 years. Energy exports, whether heat or power, would presumably replace fossil fuel. Consequently, the greenhouse gas emissions in society would decrease by thousands of tons per year. In the future it might be possible to decrease the power consumption in the refining process, resulting in a decrease of the steam surplus. With process integration, the power input can be decreased by 30 % before there is a steam deficit. This option offers a good opportunity for profit as well as decreased environmental impact.
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| 27. |
- Axelsson, Erik Marcus Kristian, 1974, et al.
(författare)
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Profitability and off-site CO2-emission reduction from energy savings in the pulp and paper industry in different future energy markets
- 2012
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Ingår i: International Journal of Energy Research. - : Hindawi Limited. - 1099-114X .- 0363-907X. ; 36:9, s. 975-986
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Tidskriftsartikel (refereegranskat)abstract
- Previous studies by the authors have shown that energy savings in pulp and paper mills offer opportunities forincreased electricity production on-site or wood fuel export. The energy export implies reductions in CO2 emissions off-site, where fossil fuel or fossil-fuel-based electricity is replaced. To assess this potential and the related profitability for a future situation, four energy market scenarios were used. For a typical Scandinavian mill, the potential for CO2-emission reductions was 15–140 kton year-1 depending on the scenario and the form of energy export. Extrapolated to all relevant mills in Sweden, the potential was 0.4–3.1 Mton year-1, which is in the order of percent of the Swedish CO2 emissions. Wood fuel export implies larger reduction in CO2 emissions in most scenarios. In contrast, electricity export showed better economy in most of the cases studied; with annual earnings of 5–6Mh, this is an economically robust option. In the market pulp mill investigated, the wood fuel export was in the form of lignin. Lignin could possibly be valued as oil, regarding both price and potential for CO2-emissionreduction, making lignin separation an option with good profitability and large reductions of CO2 emissions.
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| 28. |
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| 29. |
- Axelsson, Helén, 1971, et al.
(författare)
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A New Methodology for Greenhouse Gas Reduction in Industry through Improved Heat Exchanging and/or Integration of Combined Heat and Power
- 1999
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Ingår i: Applied Thermal Engineering. ; 19/1999, Issue 7, s. 707-731
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a method that identi®es economically optimal combinations of enhanced heat recovery, integration of combined heat and power (CHP), and fuel switching, in an existing industrial energy system at various emission levels. Novel types of composite curves based on pinch technology, representing the existing temperature levels for supplying heat and the possible ones that may be attained after retro®tting, are used as tools for estimating the opportunities for CHP and the trade-off between improved heat exchangin
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| 30. |
- Axelsson, Helén, 1971, et al.
(författare)
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Potential for Greenhouse Gas Reduction in Industry through Increased Heat Recovery and/or Integration of Combined Heat and Power
- 2003
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Ingår i: Applied Thermal Engineering. - 1404-7098. ; 23:1, s. 65-87
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Tidskriftsartikel (refereegranskat)abstract
- The potential for greenhouse gas (GHG) reduction in industry through process integration measures depends to a great extent on prevailing technical and economic conditions. A step-wise methodology developed at the author's department based on pinch technology was used to analyse how various parameters influence the cost-optimal configuration for the plant's energy system, and the opportunities for costeffective GHG emissions reduction compared to this solution. The potential for reduction of GHG emissions from a given plant depends primarily on the design of the industrial process and its energy system (internal factors) and on the electricity-to-fuel price ratio and the specific GHG emissions from the national power generation system (external factors).
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