Heat recovery in a milk powder spray-drying process

Abstract

Energy used for processing in food and beverages factories is one of the most single expensive aspects of the entire process. Organisations depend on using recovered energy where possible to curb the cost of generating new energy. Heat recovery, therefore, becomes the area of focus to ensure that the total cost of energy is reduced. Furthermore, expanding organisations are most likely to depend on recovered energy sources for process optimisation and expansion. It has been hypothesised that there is a significant premium for recovering high-temperature heat energy and exhausting it to the atmosphere at the lowest temperature possible. The aim of this study is to investigate the factors affecting the optimization of production of milk powder in a spray-drying process, with an argument that the heat energy in the exhaust air of the final stage of the drying process can be used to optimize the production capacity and energy demand of the process. The aim focuses specifically on ascertaining if the heat energy is recoverable, evaluating the amount of energy that is lost to the atmosphere, exploring the most economical way of using recovered energy, determining the expected optimization as a result of using recovered energy and evaluating the cost associated with recovering heat energy. A qualitative research approach was used to understand the underlying problems and challenges in exhaust heat recovery. Based on the aforementioned challenges, a quantitative method was used to ascertain possible solutions to exhaust heat recovery. The findings from the primary research concluded that there is a significant amount of energy lost to the atmosphere which is recoverable. The results revealed that approximately 5 300 MJ of energy exit to the atmosphere on an hourly basis during production. Both the primary and secondary research revealed that the major challenge facing heat recovery is matching the recovered heat source to the heat sink in the process. The study recommends that the most simple and economical way to use the recovered heat in spray-drying processes is to pre-heat the incoming fresh air. The study also recommends that the heat recovery systems should be well-designed and energy-saving-oriented to achieve the desired results. The capital cost of adopting an exhaust heat recovery system is high; however, the return on investment renders the investment lucrative.