Spillvärmeåtervinning

Sammanfattning: SAPA´s resource of waste heat is the basis for this thesis to investigate the possibility of energy assets in their cooling water and possible uses for it. The energy in the waste water is greater than the current need which has three uses which are (1) heating the factory, (2) converting liquid propane to propane gas and (3) local domestic heating. The average energy load that is available is 1, 7 MW and the average temperature in the cooling water is 41°C. The total energy load at dimensioning out side temperature is approximately 1,6 MW for the three current uses. The temperature is currently too low to be used directly in the existing systems so an upgrade is needed. The district heating has the highest temperature requirements at 100°C in the winter. To reach the relatively high temperatures required a hybrid heat pump proves to be a suitable solution due to a good Coefficient of Performance (COP). The disadvantage is that at the moment hybrid heat pumps have to be tailor made and are therefore very expensive. The investment required to extract the most amount of surplus energy is large due to the expensive tailor made hybrid heat pumps and the high cost of laying underground heat transferring pipes which leads to long pay off times as the value of surplus heat from waste water is low.