This project is the closing part of the education as Technology Management and Marine Engineering at Aarhus School of Marine and Technical Engineering. The report is made in connection with a 50 day internship at De Danske Gærfabrikker A/S (DDGF) in Grenaa, where they produce different kinds of yeast for e.g. baking and wine production.
The subject of the report has been chosen in corporation with the leading Maintenance Technician at DDGF, Jack Domino. The report is a combination of relevant theory and practice from the internship.
DDGF wishes to reduce the costs related to energy consumption in means of steam. Therefore we chose this specific subject to be the foundation of our project.
Today DDGF buys the steam from the local combined heat and power plant, but it has been announced that the price will be increased by 40% in 2018. This will have a serious influence on DDGF’s economy, because every year they use a significant amount of steam.
During the internship we discovered that DDGF cools down a significant amount of warm cooling water from different processes.
A part of this energy is used for preheating different process fluids during the production of yeast. When the process fluids have been preheated, it is further heated by steam. The preheating system is named the 60 °C system, because the temperature is approximately 60 °C.
Even though some of the energy from the cooling water is used for preheating, the largest amount of it is cooled down by cooling towers.
The aim of this report is to investigate the opportunities of installing a heat pump that uses some of the warm cooling water and increases the temperature at the 60 °C system to approximately 80 °C. By increasing the temperature from approximately 60 °C to approximately 80 °C, the steam consumption should be reduced because most of the process fluids are not heated more than 80 °C.
The report contains a mapping of the energy consumption from the 60 °C system and also from the steam system used for supply heating. This mapping is made to give a general view of the different consumers in the 60 °C- and the steam system, respectively.
Furthermore the report contains a description of the economic aspects of investing in a heat pump plant at DDGF. It is explained how the investment could be formed and how profitable it would be. It is also described what other issues should be considered before making an investment in a heat pump plant.
Some of these issues are for example how to achieve the best COP of the exact plant, and also which working environmental aspects the company must be aware of. The purpose of these considerations is to give a realistic overview of the whole investment.