Technological breakthrough and innovation in the production of whey powders with 30-40 % reduction in energy costs

There are two essential stages in the elimination of water for the production of whey and permeate powders: concentration by vacuum evaporation followed by spray drying. These two operations alone represent 25% of the energy consumed by the French dairy industry, the major part of which is due to the drying stage. Indeed, 96.7% of the whey water is removed during the vacuum evaporation/concentration stage, whereas drying, which removes only 3.3% of the water, requires 31% of the total energy used over the entire process.One possible way to reduce energy consumption would be for the product to enter the drying tower at a higher level of dryness. We therefore propose replacing the drying tower with rotating evaporators, i.e. equipment adapted to highly viscous products able to pass from a liquid state to a granular state by a continuous process.The process begins as normal with the concentration of the whey/permeate from 6 to 60% dry matter in vacuum evaporators, followed by crystallisation of the concentrate in a tank. However, instead of passing through a drying tower, the concentrate then undergoes 60–80% superconcentration in a rotating fine layer evaporator. This highly viscous superconcentrate is then granulated in a second fine layer evaporator to recycle the powder created by the previous process. The granules thus obtained are then dried on a fluid bed to 96-97% dry matter.The patented PST process (Poudre Sans Tour/Towerless Powder – n° FR1457413) constitutes a true technological breakthrough in the manufacture of whey powders, with physical and rehydration properties comparable to those obtained with a drying tower. It has been validated on pilot equipment producing 50kg.h-1 powder and consuming significantly less energy. On the basis of theoretical calculations, the energy cost is 7.2 MJ/t of powder with the PST process compared to 11.9 MJ/t with the classical process, i.e. an energy saving of 40%. Setting up of the equipment does not require location investment such as the construction of a building to accommodate a tower, thus providing an additional saving of approximately 40% on the costs of installation.