Energy audit with improvements at Norrmejeriers dairy in Umeå : The powder manufacturing process

This thesis estimates the energy required to manufacture two different powder types at Norrmejeriers dairy in Umeå. Some work has also been done trying to find improvements in the manufacturing process of the powder to reduce the energy consumption. Background to the work is Norrmejeriers participation in Swedish Energy Agency’s program for energy efficiency in large industries. The evaporation plant uses approximately 16,5 GWh per year associated to steam used in the drying process according to the energy audit that was made in 2013 by Sweco. The evaporation plant at the dairy is in the current situation the most significant energy aspect in terms of oil, electricity, biogas and water. These 16.5 GWh distributed in a number of different drying processes, two different types of evaporators and a spray drying process. These processes have in this thesis have been mapped over a number of days of production, where whey volumes, steam consumption and operating- and production time was noted. Thereafter, the specific energy per liter of concentrate or powder from each individual device is calculated. This is to see how the energy demand differs between the different production methods and powder types. The results showed that the specific energy use in powder manufacturing varies between 3,02 kWh/liter for whey powder and 4,60 kWh/liter for whey protein concentrate. The result, however, depends on the involved drying processes, when the specific energy use of the devices ranges from 0,28 kWh/liter and 3,62 kWh/liter. When these values was compared consideration should be taken of the whey volumes processed each year which is over 31 km3 for manufacturing whey powder and over 20 km3 for whey protein concentrate. In the thesis five different suggestions are presented to reduce the energy use in powder manufacturing. Three of these proposals are more energy economic but not possible due high investment costs. One of the five proposals presented and deemed feasible in the near future would mean an annual energy saving of 550 MWh. This means an annual saving of 275 tSEK with an assumed energy price of 500 SEK/MWh. The other proposal as deemed feasible and is presented is a number of engine replacements. This proposal shows that energy savings between 3-20 MWh/year can be done but is not economically justified as the repayment periods for engines exceeds its warranty periods. The fact that there are few flow meters in the steam system in the department and the equipment that stores the values of heat consumption is not calibrated in many years Norrmejerier have no clear picture of the powder manufacture's impact on the department's energy use. Further deemed an opportunity for energy savings exists in integrating the thinking of energy efficiency in product planning. Then unnecessary down time and idle runs can be avoided, thereby saving energy. This has no estimates have been made, but in consultation with staff at Norrmejerier are some savings