title: Integrating heat recovery from milk powder spray dryer exhausts in the dairy industry

authors: Atkins, Martin John

subjects: process integration

abstract: Heat recovery from milk powder spray dryer exhausts has proven challenging due to both economic and thermodynamic constraints. Integrating the dryer with the rest of the process (e.g. evaporation stages) can increase the viability of exhaust recovery. Several potential integration schemes for a milk powder plant have been investigated. Indirect heat transfer via a coupled loop between the spray dryer exhaust and various heat sinks were modeled and the practical heat recovery potential determined. Hot utility use was reduced by as much as 21% if suitable heat sinks are selected. Due to high particle loading and operating temperatures in the particle sticky regime, powder deposition in the exhaust heat exchanger is perhaps the greatest obstacle for implementing heat recovery schemes on spray dryers. Adequate cleaning systems are needed to ensure continuous dyer operation.

text: Integrating heat recovery from milk powder spray dryer exhausts in the dairy industry Heat recovery from milk powder spray dryer exhausts has proven challenging due to both economic and thermodynamic constraints. Integrating the dryer with the rest of the process (e.g. evaporation stages) can increase the viability of exhaust recovery. Several potential integration schemes for a milk powder plant have been investigated. Indirect heat transfer via a coupled loop between the spray dryer exhaust and various heat sinks were modeled and the practical heat recovery potential determined. Hot utility use was reduced by as much as 21% if suitable heat sinks are selected. Due to high particle loading and operating temperatures in the particle sticky regime, powder deposition in the exhaust heat exchanger is perhaps the greatest obstacle for implementing heat recovery schemes on spray dryers. Adequate cleaning systems are needed to ensure continuous dyer operation.

year: 2011

title: Predicting the effects of climate change on trophic status of three morphologically varying lakes: Implications for lake restoration and management

authors: Trolle, Dennis

subjects: DYRESM-CAEDYM

abstract: To quantify the effects of a future climate on three morphologically different lakes that varied in trophic status from oligo-mesotrophic to highly eutrophic, we applied the one-dimensional lake ecosystem model DYRESM-CAEDYM to oligo-mesotrophic Lake Okareka, eutrophic Lake Rotoehu, both in the temperate Bay of Plenty region, and highly eutrophic Lake Ellesmere, in the temperate Canterbury region, New Zealand. All three models were calibrated for a three-year period and validated for a separate two-year period. The model simulations generally showed good agreement with observed data for water column temperature, dissolved oxygen (DO), total phosphorus (TP), total nitrogen (TN) and chlorophyll a (Chl a) concentrations. To represent a possible future climate at the end of this century, mean annual changes in air temperature by 2100, derived from the IPCC A2 scenario downscaled for these lake regions, were added to the daily baseline temperatures for years 2002–2007. Lake model simulations using this future climate scenario indicate differential increases in eutrophication in all three lakes, especially during summer months. The predicted effects on annual mean surface water concentrations of TP, TN and Chl a will be equivalent to the effects of increasing external TN and TP loading by 25–50%. Simulations for the polymictic, eutrophic Lake Rotoehu further indicate that cyanophytes will be more abundant in the future climate, increasing by >15% in their contribution to annual mean Chl a. Therefore, future climate effects should be taken into account in the long-term planning and implementation of lake management as strategies may need to be refined and adapted to preserve or improve the present-day lake water quality.

text: Predicting the effects of climate change on trophic status of three morphologically varying lakes: Implications for lake restoration and management To quantify the effects of a future climate on three morphologically different lakes that varied in trophic status from oligo-mesotrophic to highly eutrophic, we applied the one-dimensional lake ecosystem model DYRESM-CAEDYM to oligo-mesotrophic Lake Okareka, eutrophic Lake Rotoehu, both in the temperate Bay of Plenty region, and highly eutrophic Lake Ellesmere, in the temperate Canterbury region, New Zealand. All three models were calibrated for a three-year period and validated for a separate two-year period. The model simulations generally showed good agreement with observed data for water column temperature, dissolved oxygen (DO), total phosphorus (TP), total nitrogen (TN) and chlorophyll a (Chl a) concentrations. To represent a possible future climate at the end of this century, mean annual changes in air temperature by 2100, derived from the IPCC A2 scenario downscaled for these lake regions, were added to the daily baseline temperatures for years 2002–2007. Lake model simulations using this future climate scenario indicate differential increases in eutrophication in all three lakes, especially during summer months. The predicted effects on annual mean surface water concentrations of TP, TN and Chl a will be equivalent to the effects of increasing external TN and TP loading by 25–50%. Simulations for the polymictic, eutrophic Lake Rotoehu further indicate that cyanophytes will be more abundant in the future climate, increasing by >15% in their contribution to annual mean Chl a. Therefore, future climate effects should be taken into account in the long-term planning and implementation of lake management as strategies may need to be refined and adapted to preserve or improve the present-day lake water quality.

year: 2010

title: Developing restorative practices in schools: Some reflections

authors: Drewery, Wendy

subjects: Counselling

abstract: The use of disciplinary practices derived from restorative justice have recently been gaining popularity and inciting keen interest in the education community. Practices that have so far been introduced have tended to centre on conferencing, although there is a broadening range of other practices in schools that are being brought under the heading “restorative”. This paper offers some reflections on these developments, building on the experiences of a team at the University of Waikato, which completed two projects on restorative conferencing in schools for the Ministry of Education under the rubric of the Suspension Reduction Initiative, and continues to develop understanding of the practices. The projects included developing and trialling processes for suspension hearings using restorative conferencing and principles from restorative justice. Objectives of both projects were related to the desire to reduce numbers of suspensions and exclusions, particularly of Māori children. We argue that the introduction of restorative practices invites schools into some tectonic shifts in thinking about offending behaviour, about community, and ultimately about the purposes of education.

text: Developing restorative practices in schools: Some reflections The use of disciplinary practices derived from restorative justice have recently been gaining popularity and inciting keen interest in the education community. Practices that have so far been introduced have tended to centre on conferencing, although there is a broadening range of other practices in schools that are being brought under the heading “restorative”. This paper offers some reflections on these developments, building on the experiences of a team at the University of Waikato, which completed two projects on restorative conferencing in schools for the Ministry of Education under the rubric of the Suspension Reduction Initiative, and continues to develop understanding of the practices. The projects included developing and trialling processes for suspension hearings using restorative conferencing and principles from restorative justice. Objectives of both projects were related to the desire to reduce numbers of suspensions and exclusions, particularly of Māori children. We argue that the introduction of restorative practices invites schools into some tectonic shifts in thinking about offending behaviour, about community, and ultimately about the purposes of education.

year: 2005