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02500 The potential for energy savings when reducing the water consumption in a Kraft pulp mill
17 Energy conversion and recycling
17
E N E R G Y CONVERSION A N D RECYCLING
06/02496 Analysis of using gasification and incineration for thermal processing of wastes B6bar, L. et al. Applied Thermal Engineering, 2005, 25, (7), 1045 1055. The contribution discusses the possibility of utilizing gasification as the first part of a two-stage waste thermal treatment technology. The application of gasification brings a number of improvements over the conventional oxidizing approach. These include, for example, the fact that the primary thermal waste decomposition is performed under temperatures below the melting point of the ash material and that substantial savings of the auxiliary fuel in the after-burner chamber are achieved by exploiting the heat value of the gasification products. In experiments gasification specifications and composition of products are studied. The gasification was carried out within the temperature range 800-860°C and in the presence of air entering at stoichiometric ratios between 0.15 and 0.25. The waste was mostly a mixture of shredded textiles and rubber, with a heat value of 33 MJ/kg. The model equipment could treat maximum 40 kg of waste per hour. Based on the results of the waste gasification testing, heat and mass balances of the incineration plant with capacity of 10 kt/year of industrial waste were evaluated and the results compared with conditions required in an incineration plant operating under an oxidation regime.
06/02497
Carbon dioxide - new uses for an old refrigerant
Pearson, A. International Journal of Refrigeration, 2005, 28, (8), 1140 1148. Carbon dioxide has been used as a refrigerant in vapour compression systems of many types for over 130 years, but it is only in the last decade that inventive minds and modern techniques have found new ways to exploit the uniquely beneficial properties of this remarkable substance. This paper traces the development of the old carbon dioxide systems, considers the technical, commercial and social reasons for their slow development and subsequent decline and examines the recent renaissance across a surprisingly broad range of applications, from trans-critical car air conditioners to low temperature industrial freezer plants. The paper then concentrates on industrial refrigeration systems, which were the basis of early developments in the period 1865-1885, but which have been somewhat overlooked in the current renaissance. The paper concludes with a review of possible future developments, indicating the areas of research and product development required to maximize the potential of the only non-toxic, nonflammable, non-ozone-depleting, non-global-warming refrigerant available for Rankine cycle vapour compression systems in the 21st century.
06/02498 Comparative analysis of different extraction methods for hydrocarbons present in industrial waste waters Santa, J.-R. et al. Ciencia Tecnologia y Futuro, 2002, 2, (3), 49-60. A comparison among four extraction techniques such as: liquid-liquid (LLE), solid phase extraction (SPE), solid phase microextraction (SPME) and static headspace (S-HS) was carried out. The main purpose of this research was to determine the highest recovery effieiencies and how reproducible the tests are while varying parameters such as time, extraction technique, type of solvents and others. Chromatographic parameters were optimized in order to carry out the analyses. Quantification of residual waters in the hydrocarbons was achieved by using a high-resolution gas chromatography with a gas flame ionization detector (HRGC-FID). Validation of the method was carried out by analysing real samples taken in different sampling places of the residual waters treatment plant of Ecopetrol-Barrancabermeja. The use of extraction methods that require large quantities of solvent and involve long periods of time for analysis are losing validity day by day. Techniques such as the HS-SPME and static HS, are offered as alternatives for quantifying hydrocarbons. They require a total lack of solvents, provide high sensibility, selectivity and the techniques are reproducible. Solid phase microextration (SPME) and static headspace (static HS) techniques were chosen as the extraction techniques to
376
Fuel and Energy Abstracts September 2006
validate the method in real samples. Both techniques showed similar results for the determination of total hydrocarbons (in the gasoline range).
06/02499 Heat recovery and floating condensing in supermarkets Arias, J. and Lundqvist, P. Energy and Buildings, 2006, 38, (2), 73-81. Supermarkets are great energy users in many countries, The potential for increased energy efficiency is large. One option is to utilize heat recovery (or heat reclaim) from condensers to heat the premises. Obviously this option is only interesting in relatively cold areas such as northern Europe, Canada, etc. An alternative to heat recovery is floating condensing pressure, which improves the coefficient of performance and decreases the energy consumption of the refrigeration system at lower outdoor temperature. Both heat recovery and floating condensing pressure can be utilized interchangeably depending on the heat requirements of the premises. A computer model that calculates the energy consumption in a supermarket with the possibility to simulate different system solutions for the refrigeration system has been developed at the Royal Institute of Technology, Department of Energy Technology. The software 'CyberMart' is used in the present study to compare the potential of heat recovery and floating condensing in Swedish supermarkets. Measurements of different parameters such as temperatures, relative humidity and compressor power have been carried out in different supermarkets with heat recovery to validate the theoretical calculations. The present study shows that heating requirements can be covered completely by heat reclaim from the condenser. However, practical experiences show that installations are less efficient due to poor system solutions and/or control strategies. According to the results from CyberMart, the highest potential of energy saving is obtained from using a systems solution with both heat recovery and floating condensing.
06/02500 The potential for energy savings when reducing the water consumption in a Kraft pulp mill Wising, U. et al. Applied Thermal Engineering, 2005, 25, (7), 1057 1066. An existing pulp and paper mill has been studied regarding the reduction of water consumption, and the resulting increased potential for energy integration. When the mill's hot water consumption is decreased, the live steam demand for the mill also decreases. Also when decreasing the hot water consumption, the quantity and temperature of available excess heat increases. This excess heat can be used for evaporation, thereby reducing the live steam demand further by up to 1.5 GJ/t. A pinch analysis was performed and it was found that when removing pinch violations the hot water consumption is not an important factor any more. Removing all the pinch violations and using the remaining excess heat for evaporation yields a significantly larger energy savings for the mill (4.0 G J/t). From an economic optimum perspective it is probably most profitable to do a combination of reducing water consumption, removing pinch violations, and use the remaining excess heat for evaporation.
06/02501 Waste heat recovery in the production of furnacegrade phosphoric acid Liu, B. Q. and Jiang, J. L. Journal oJ'the Energy Institute, 2006, 79, (1), 59 64. In order to improve energy conservation and environmental protection, an improved process for the production of furnace-grade phosphoric acid and new phosphoric furnace with heat recovery is proposed. This process succeeds in recovering and utilizing thermal energy released by the combustion of elemental phosphorous. As a result, the special steam boiler and plate heat exchanger used in the conventional process are not required. The combustion chamber, consisting of a vertical tube bundle, itself provides a heat exchange surface and the cooling water is circulated in a system consisting of a drum, downtakes, lower manifold, ascending tubes, upper manifold and collecting tubes. An energy and exergy analysis of the overall process reveals the energy and exergy distribution in the preparation of furnace-grade phosphoric acid and illustrates the effect on energy conservation. Some structural shortcomings of the new phosphoric furnace to be overcome are also analysed and corresponding recommendations are proposed.
17
E N E R G Y CONVERSION A N D RECYCLING
06/02496 Analysis of using gasification and incineration for thermal processing of wastes B6bar, L. et al. Applied Thermal Engineering, 2005, 25, (7), 1045 1055. The contribution discusses the possibility of utilizing gasification as the first part of a two-stage waste thermal treatment technology. The application of gasification brings a number of improvements over the conventional oxidizing approach. These include, for example, the fact that the primary thermal waste decomposition is performed under temperatures below the melting point of the ash material and that substantial savings of the auxiliary fuel in the after-burner chamber are achieved by exploiting the heat value of the gasification products. In experiments gasification specifications and composition of products are studied. The gasification was carried out within the temperature range 800-860°C and in the presence of air entering at stoichiometric ratios between 0.15 and 0.25. The waste was mostly a mixture of shredded textiles and rubber, with a heat value of 33 MJ/kg. The model equipment could treat maximum 40 kg of waste per hour. Based on the results of the waste gasification testing, heat and mass balances of the incineration plant with capacity of 10 kt/year of industrial waste were evaluated and the results compared with conditions required in an incineration plant operating under an oxidation regime.
06/02497
Carbon dioxide - new uses for an old refrigerant
Pearson, A. International Journal of Refrigeration, 2005, 28, (8), 1140 1148. Carbon dioxide has been used as a refrigerant in vapour compression systems of many types for over 130 years, but it is only in the last decade that inventive minds and modern techniques have found new ways to exploit the uniquely beneficial properties of this remarkable substance. This paper traces the development of the old carbon dioxide systems, considers the technical, commercial and social reasons for their slow development and subsequent decline and examines the recent renaissance across a surprisingly broad range of applications, from trans-critical car air conditioners to low temperature industrial freezer plants. The paper then concentrates on industrial refrigeration systems, which were the basis of early developments in the period 1865-1885, but which have been somewhat overlooked in the current renaissance. The paper concludes with a review of possible future developments, indicating the areas of research and product development required to maximize the potential of the only non-toxic, nonflammable, non-ozone-depleting, non-global-warming refrigerant available for Rankine cycle vapour compression systems in the 21st century.
06/02498 Comparative analysis of different extraction methods for hydrocarbons present in industrial waste waters Santa, J.-R. et al. Ciencia Tecnologia y Futuro, 2002, 2, (3), 49-60. A comparison among four extraction techniques such as: liquid-liquid (LLE), solid phase extraction (SPE), solid phase microextraction (SPME) and static headspace (S-HS) was carried out. The main purpose of this research was to determine the highest recovery effieiencies and how reproducible the tests are while varying parameters such as time, extraction technique, type of solvents and others. Chromatographic parameters were optimized in order to carry out the analyses. Quantification of residual waters in the hydrocarbons was achieved by using a high-resolution gas chromatography with a gas flame ionization detector (HRGC-FID). Validation of the method was carried out by analysing real samples taken in different sampling places of the residual waters treatment plant of Ecopetrol-Barrancabermeja. The use of extraction methods that require large quantities of solvent and involve long periods of time for analysis are losing validity day by day. Techniques such as the HS-SPME and static HS, are offered as alternatives for quantifying hydrocarbons. They require a total lack of solvents, provide high sensibility, selectivity and the techniques are reproducible. Solid phase microextration (SPME) and static headspace (static HS) techniques were chosen as the extraction techniques to
376
Fuel and Energy Abstracts September 2006
validate the method in real samples. Both techniques showed similar results for the determination of total hydrocarbons (in the gasoline range).
06/02499 Heat recovery and floating condensing in supermarkets Arias, J. and Lundqvist, P. Energy and Buildings, 2006, 38, (2), 73-81. Supermarkets are great energy users in many countries, The potential for increased energy efficiency is large. One option is to utilize heat recovery (or heat reclaim) from condensers to heat the premises. Obviously this option is only interesting in relatively cold areas such as northern Europe, Canada, etc. An alternative to heat recovery is floating condensing pressure, which improves the coefficient of performance and decreases the energy consumption of the refrigeration system at lower outdoor temperature. Both heat recovery and floating condensing pressure can be utilized interchangeably depending on the heat requirements of the premises. A computer model that calculates the energy consumption in a supermarket with the possibility to simulate different system solutions for the refrigeration system has been developed at the Royal Institute of Technology, Department of Energy Technology. The software 'CyberMart' is used in the present study to compare the potential of heat recovery and floating condensing in Swedish supermarkets. Measurements of different parameters such as temperatures, relative humidity and compressor power have been carried out in different supermarkets with heat recovery to validate the theoretical calculations. The present study shows that heating requirements can be covered completely by heat reclaim from the condenser. However, practical experiences show that installations are less efficient due to poor system solutions and/or control strategies. According to the results from CyberMart, the highest potential of energy saving is obtained from using a systems solution with both heat recovery and floating condensing.
06/02500 The potential for energy savings when reducing the water consumption in a Kraft pulp mill Wising, U. et al. Applied Thermal Engineering, 2005, 25, (7), 1057 1066. An existing pulp and paper mill has been studied regarding the reduction of water consumption, and the resulting increased potential for energy integration. When the mill's hot water consumption is decreased, the live steam demand for the mill also decreases. Also when decreasing the hot water consumption, the quantity and temperature of available excess heat increases. This excess heat can be used for evaporation, thereby reducing the live steam demand further by up to 1.5 GJ/t. A pinch analysis was performed and it was found that when removing pinch violations the hot water consumption is not an important factor any more. Removing all the pinch violations and using the remaining excess heat for evaporation yields a significantly larger energy savings for the mill (4.0 G J/t). From an economic optimum perspective it is probably most profitable to do a combination of reducing water consumption, removing pinch violations, and use the remaining excess heat for evaporation.
06/02501 Waste heat recovery in the production of furnacegrade phosphoric acid Liu, B. Q. and Jiang, J. L. Journal oJ'the Energy Institute, 2006, 79, (1), 59 64. In order to improve energy conservation and environmental protection, an improved process for the production of furnace-grade phosphoric acid and new phosphoric furnace with heat recovery is proposed. This process succeeds in recovering and utilizing thermal energy released by the combustion of elemental phosphorous. As a result, the special steam boiler and plate heat exchanger used in the conventional process are not required. The combustion chamber, consisting of a vertical tube bundle, itself provides a heat exchange surface and the cooling water is circulated in a system consisting of a drum, downtakes, lower manifold, ascending tubes, upper manifold and collecting tubes. An energy and exergy analysis of the overall process reveals the energy and exergy distribution in the preparation of furnace-grade phosphoric acid and illustrates the effect on energy conservation. Some structural shortcomings of the new phosphoric furnace to be overcome are also analysed and corresponding recommendations are proposed.