Matthias Philipp

Total site utility systems optimisation for milk powder production

This study applies the Total Site Heat Integration method, in conjunction with a detailed process and utility model, to investigate three methods to increase the energy efficiency of the utility supply system for milk powder production. Sequentially explored opportunities are: (1) increasing boiler efficiency through condensing economisers, (2) waste heat recovery from the chiller unit, and (3) Combined Heat and Power (CHP) for electricity production. The basis for the analysis is the anticipated future milk powder process design, which incorporates results from recent studies that have focused on improving the process design and integration of the heat treatment and evaporator systems and recovering heat from the spray dryer exhaust, which show a combined specific fuel consumption reduction of 29.6 % and a relatively small increase in electricity use of 4.5 %. To maximise boiler efficiency, the study concludes that a condensing economiser for the flue gas can be indirectly matched with heating fluidised bed air flows through the boiler condensate system, which results in specific fuel use reduction of 227 MJ/tp. Chiller waste heat can be upgraded and integrated as a heat source to replace the equivalent specific fuel use of 101 MJ/tp through integration with the site low temperature hot water loop. By designing the steam system to maximise electricity generation in a new turbine, results show that 51 % of the site’s electricity demand may be satisfied by CHP. The combined effect of implementing these three utility systems opportunities is a specific fuel use of 3,868 MJ/tp, of which 530 MJ/tp result from electricity production, and a specific grid electricity demand of 113.4 kWh/tp.

Carbon emissions efficiency and economics of combined heat and power in New Zealand

Combined Heat and Power (CHP) or cogeneration, is a common and often cost effective method to maximise the efficiency and utilisation of fossil fuels. Greenhouse Gas (GHG) emissions from the electricity generated using CHP is also an important factor to consider, especially within the framework of emissions reduction and uptake of renewable generation. This paper will present a detailed analysis of the economics of industrial CHP within New Zealand and examine the potential of CHP to contribute to GHG emissions reduction. An emissions factor from electricity generation using CHP is defined based on the marginal efficiency of electricity generation. The economics of CHP in New Zealand can be favourable under certain conditions although the emissions of generation using fossil fuels in all cases was higher than grid purchased electricity, due to high levels of renewable generation. A reduction in emissions can occur in countries that have medium to high Grid Emissions Factors (GEF) such as the US, UK, Australia, India, and China. Countries with GEF less than around 0.2 tCO2‐eq/MWel would need to utilise biomass to achieve large emissions reductions using CHP. Powered by TCPDF (www.tcpdf.org) PRES17 conference

Optimal energy supply structures for industrial sites in different countries considering energy transitions: A cheese factory case study

This present study focuses on analysing the most efficient utility energy supply structure in terms of primary energy efficiency, carbon emissions and energy costs. In the German dairy industry, separate conversion with gas fired steam boiler, and cooling with ammonia chillers are the-state-of-the-art technologies. It is attractive due to its robustness and low investment costs. But given the ongoing energy transition to renewable energy, opportunities to reduce emissions will become increasingly important. There are other energy supply options, such as Combined Heat and Power (CHP) and Heat Pumps (HP), that if implemented need to compete against the conventional energy supply systems. One option is CHP to provide cogenerated electricity and heat while cooling remains supplied by ammonia chillers. In countries with high electricity Grid Emissions Factors (GEF) such as Germany and the USA, the use of decentralised CHP results in savings of primary energy and emissions. However, this option is less attractive for countries with low GEF such as France and Norway, and for places like Germany where the energy transition lowering its GEF by 50 % in 2030. In these cases, HP solutions provide the lowest emissions and highest primary energy efficiency.

Energy Efficiency Measures for Batch Retort Sterilization in the Food Processing Industry

The purpose of this study is to highlight the energy saving potentials of a batch retort sterilization process operated by steam and to develop concepts for improving its energy efficiency. By using the methodical approach of the Onion Diagram and the recovery of low grade heat sources, four comprehensive improved energy efficiency concepts have been developed. Two concepts increase the initial product temperature resulting in lower transient steam consumption rates and a decreased energy demand. The other two options transform the waste heat and the energy for product cooling into heat streams for supplying nearby heat sinks or other processes in the plant. Results show that the total energy demand can be reduced by more than 23 % and 42 % of the energy injected into the system can be recovered. The scope of the study focused on a single, independent retort to ensure the transferability of the concepts. This study also shows, using a practical example, the importance of a comprehensive process understanding and analysis prior to application of Pinch Analysis, which is needed to ensure that the correct waste heat stream temperatures are defined, necessary processing constraints are appreciated, and all possible heat sinks in the process are considered.

Hybrid-heating-systems for Optimized Integration of Low-temperature-heat and Renewable Energy

The food and beverage industries are significant industrial producers of green-house gas (GHG) emissions. Reductions can be achieved by increased energy efficiency and the use of renewable energy to replace fossil fuel use. The main efficiency method within this industries is the use of low temperature heat (LTH), i.e. below 100 °C. Sources for LTH include heat recovery from process flows, heat rejection from utility operations (i.e. chillers, combined heat and power (CHP), condensing economisers), and renewable energy (i.e. solar thermal). A hybrid heating system (HS) has been developed that can retrofit steam heater designs for the integration of LTH. Two different systems have been found, for adapting direct and indirect steam heaters, either installing an extra hot water heater or using the indirect hot water loop for the integration. In both systems the existing steam heater remains a part of the system for individual back-up. The set-up and the control algorithm of the HS allow installing a 37 % smaller hot water grid than a common design with one central back-up heater. Investigations using a comprehensive model of a whey separation and drying plant showed that implementing a piston engine CHP unit combined with the HS reduce the energy costs by 42 % and the GHG emissions by 33 %.