Optimal waste stream discharge temperature selection for dryer operations using thermo-economic assessment

A typical drying process that has liquid and gas discharge streams has been analysed and the impact of selecting various combinations of soft temperatures on heat recovery, utility targets, area targets, capital cost and total cost is reported. The method is based on the plus-minus principle and traditional pinch analysis methods for utility, area and capital cost targeting with the modification of using a ΔT contribution. Results show that there is significant benefit from optimising discharge temperatures for total cost. To achieve minimum energy consumption and total cost, heat recovery from the dryer exhaust air is necessary. Heat recovery from liquid heat sources is shown to be preferable over gas streams due to a higher film coefficient resulting in less heat exchanger area and capital cost. There is also value in making process modifications, such as combining streams or removing small streams to be solely heated by utility, to reduce the number of network heat exchangers. For the best case, the discharge temperatures of the leaving streams are 18.0 °C for water condensate (liquid stream) and 52.4 °C for the exhaust air (gas stream)

Minimising energy use in milk powder production using process integration techniques

Spray drying of milk powder is an energy intensive process and there remains a significant opportunity to reduce energy consumption by applying process integration principles. The ability to optimally integrate the drying process with the other processing steps has the potential to improve the overall efficiency of the entire process, especially when exhaust heat recovery is considered. However, achieving the minimum energy targets established using pinch analysis results in heat exchanger networks that, while theoretically feasible, are impracticable, unrealistic, contain large number of units, and ultimately uneconomic. Integration schemes that are acceptable from an operational point of view are examined in this paper. The use of evaporated water is an important factor to achieve both energy and water reductions. The economics of additional heat recovery seem favourable and exhaust heat recovery is economically justifiable on its own merits, although milk powder deposition should be minimised by selecting an appropriate target temperature for the exhaust air. This will restrict the amount of heat recovery but minimise operational risk from heat exchanger fouling. The thermodynamic constraints caused by the operating temperatures of the dryer and the poor economics exclude the use of heat pumps for exhaust heat recovery in the short to medium term

Optimal stream discharge temperatures for a dryer operation using a thermo-economic assessment

The application of traditional pinch analysis to processes involving waste streams require the discharge temperatures of the waste streams to be estimated prior to performing the pinch analysis

Total site targeting with stream specific minimum temperature difference

The paper focuses on extending traditional Total Site Integration methodology to produce more meaningful utility and heat recovery targets for the process design. The traditional methodology leads to inadequate results due to inaccurate estimation of the overall Total Site heat recovery targets. The new methodology is a further development of a recently extended traditional pinch methodology. The previous extension was on the introduction of using an individual minimum temperature difference (δTmin) for different processes so that the δTmin is more representative of the specific process. Further this paper deals with stream specific δT min inside each process by setting different δT contribution (δTcont) and also using different δTcont between the process streams and the utility systems. The paper describes the further extended methodology called stream specific targeting methodology. A case study applying data from a real diary factory is used to show the differences between the traditional, process specific and stream specific total site targeting methodologies. The extended methodology gives more meaningful results at the end of the targeting with this avoiding the over or under estimated heat exchanger areas in the process design

Modeling and Calculation of the Global Solar Irradiance on Slopes

The first step with regard to a simple model of a Photovoltaic Power Plant is developed in this paper based on astronomical and engineering principles. A solar irradiance model is presented in this paper that can be used to forecast the solar energy a surface on Earth is exposed to. The obtained model is verified against engineering expectations. The developed model can serve as a basis for forecasting the power of solar energy

Tectonic and climatic control on terrace formation: Coupling in situ produced 10Be depth profiles and luminescence approach, Danube River, Hungary, Central Europe

International audience\textcopyright 2015 Elsevier Ltd.The terrace sequence of the Hungarian part of the Danube valley preserves a record of varying tectonic uplift rates along the river course and throughout several climate stages. To establish the chronology of formation of these terraces, two different dating methods were used on alluvial terraces: exposure age dating using in situ produced cosmogenic 10Be and luminescence dating. Using Monte Carlo approach to model the denudation rate-corrected exposure ages, in situ produced cosmogenic 10Be samples originated from vertical depth profiles enabled the determination of both the exposure time and the denudation rate. Post-IR IRSL measurements were carried out on K-feldspar samples to obtain the ages of sedimentation.The highest terrace horizon remnants of the study area provided a best estimate erosion-corrected minimum 10Be exposure age of \textgreater700 ka. We propose that the abandonment of the highest terrace of the Hungarian Danube valley was triggered by the combined effect of the beginning tectonic uplift and the onset of major continental glaciations of Quaternary age (around MIS 22). For the lower terraces it was possible to reveal close correlation with MIS stages using IRSL ages. The new chronology enabled the distinction of tIIb (~90 ka; MIS 5b-c) and tIIIa (~140 ka; MIS 6) in the study area. Surface denudation rates were well constrained by the cosmogenic 10Be depth profiles between 5.8 m/Ma and 10.0 m/Ma for all terraces. The calculated maximum incision rates of the Danube relevant for the above determined \textgreater700 ka time span were increasing from west (\textless0.06 mm/a) to east (\textless0.13 mm/a), toward the more elevated Transdanubian Range. Late Pleistocene incision rates derived from the age of the low terraces (~0.13-0.15 mm/a) may suggest a slight acceleration of uplift towards present

Metabolites of Xenorhabdus bacteria are potent candidates for mitigating amphibian chytridiomycosis

Chytridiomycosis, caused by the chytrid fungus Batrachochytrium dendrobatidis (Bd), has caused extreme losses in amphibian biodiversity. Finding bacteria that produce metabolites with antifungal properties may turn out to be invaluable in the fight against this devastating disease. The entomopathogenic bacteria, Xenorhabdus szentirmaii and X. budapestensis produce secondary metabolites that are effective against a wide range of fungal plant pathogens. To assess whether they may also be effective against Bd, we extracted cell-free culture media (CFCM) from liquid cultures of X. szentirmaii and X. budapestensis and tested their ability to inhibit Bd growth in vitro. As a second step, using juvenile common toads (Bufo bufo) experimentally infected with Bd we also tested the in vivo antifungal efficacy of X. szentirmaii CFCM diluted to 2 and 10% (v/v), while also assessing possible malign side effects on amphibians. Results of the in vitro experiment documented highly effective growth inhibition by CFCMs of both Xenorhabdus species. The in vivo experiment showed that treatment with CFCM of X. szentirmaii applied at a dilution of 10% resulted in infection intensities reduced by ca. 73% compared to controls and to juvenile toads treated with CFCM applied at a dilution of 2%. At the same time, we detected no negative side effects of treatment with CFCM on toad survival and development. Our results clearly support the idea that metabolites of X. szentirmaii, and perhaps of several other Xenorhabdus species as well, may prove highly useful for the treatment of Bd infected amphibians

Spatial distribution of selected soil features in Hajdú-Bihar county represented by digital soil maps

L