Industriell symbios : En utredning om tillvaratagande av industriell spillvärme från en kylprocess

Sammanfattning: Energy efficiency and reduced energy consumption are two highly discussed topics in the global environmental debate where Sweden as a country is at the forefront. High demands on streamlining energy usage exists where a goal is to by 2030 have a 50% more efficient energy use than in 2005. This study examined how waste heat could be recovered from an industrial process to reintroduce it into the building and thus reduce energy consumption. The process included a test room for large motors at ABB Machines in Västerås, where a fire pond near the building was used as cooling water for the motors' cooling systems during testing. The fire pond was located underground and only the outdoor climate controlled the temperature of the water in the pond. This meant that for large parts of the year the water was too hot to be used as cooling water and thus there was a need to reduce the temperature of the pond and at the same time utilize the heat that was in it. Mass balances were performed on the fire pond using test protocols. In this way, the group was able to calculate how much energy was available to be utilized and what system temperatures were possible. After analysis of previous studies, a system solution was developed where the incoming cold water that would become domestic hot water was used to cool the fire pond and at the same time preheat the cold water. Calculations were made to prove the economic and environmental benefits of the solution. The result showed a saving of 121.89 MWh/y in district heating consumption, which corresponded to a decrease of 3.1% of the total district heating consumption. In figures, this corresponded to a gross saving of 66,730 SEK/year. In addition, the solution reduced cold water consumption by 3200 . The study showed that economic and environmental savings could be made but that the system solution was difficult to generalize as the current problem was unique. The group discussed other solutions that would have been possible if other conditions had existed for the fire pond. Among these was, for example, a proposal to upgrade the heat in the fire pond with the help of heat pumps and use this for the building's radiator circuit or for the primary district heating line. Objections to these proposals were that energy needed to be added to power the heat pumps.