Energy saving tech for crystallization plants

The dairy industry has for decades used crystallization technology to create stable particles of the milk sugar lactose. But crystallization is an energy intensive process, so here at GEA we’ve developed a heat pump technology, GEA AddCool®, that can significantly reduce the overall energy draw and operational costs of your crystallization plant, as well as reduce reliance on fossil fuels. Simultaneously generating cooling, and heating, GEA AddCool® can reduce the environmental footprint of a typical installation and help to make the crystallization process more sustainable.

Dairy processors commonly carry out lactose crystallization when producing spray dried dairy powders that contain a relatively high concentration of the lactose, which is the primary sugar found in milk. Crystallization of the lactose can make downstream spray drying easier, and potentially result in a higher quality product, with a longer shelf life. Crystallization is also used as a purification step when separating lactose out of solution. The resulting lactose crystals are almost 100% pure and can commonly be separated mechanically from the rest of the product, before washing and drying into a pure lactose product.

The processes for producing high-lactose dairy products, and for pure lactose rely on carefully controlled cooling in agitated crystallization tanks. The cooling needed is supplied by cooling tower water and/or ice water. The compressors used to generate the cold water, together with the tank agitators and the cooling water circulation pumps, account for a large proportion of the overall energy costs of a crystallization plant. GEA AddCool® CO₂ heat pump technology can help to reduce this energy burden and cost.

Heat pumps work by taking low-grade energy from a (typically) waste heat stream or air source, and upgrading that energy. The upgraded heat can then be used to produce hot water for elsewhere in the plant.

The system from which the energy was taken is effectively cooled further in the process, so, for lactose crystallization, AddCool® can offer an energy-efficient way of generating the cold water that is needed to cool the lactose-containing solution. The ice water used in the crystallization process absorbs heat as it is circulated around the tanks, and the water emerging from the outlet of the crystallization tanks will be lukewarm. GEA AddCool® heat pumps can be set up to take heat out of this lukewarm water, which effectively cools the water down so that can be fed back into the ice water reservoir. The heat that AddCool® takes out of the tank water is then further upgraded to create a separate, usable supply of hot water at temperatures of up to 130°C. This could be used, for example, to preheat the air streams for the spray dryer, resulting in significant CO₂ emission savings - up to 50 % in case of a spray dryer.

How a heat pump works

AddCool® technology harnesses the natural refrigerant CO₂, to recover waste heat for use in another process. Warm water from the crystallization tank outlet is passed through the evaporator, where the CO₂ absorbs the heat, resulting in cooling the water. The CO₂ is then passed through a compressor, where it is pressurized, elevating the temperature further. This energy is used to heat water, which in turn is channelled to preheat the air being transferred to the spray dryer.

When the heat is released the CO₂refrigerant cools, and then moves through an expansion valve that reduces the gas pressure further, so lowering the gas temperature. The cycle can then start all over again. A major advantage is that the system effectively produces hot air at the same time as the cold water, generating a double benefit.

Take a look at thevideoexplaining how the GEA AddCool® technology works.

The high efficiency of the GEA AddCool® system means that, dependent on energy prices at the time, your overall energy costs could be significantly reduced. And as well as operating a far greener process with a lower CO₂footprint, you could see a significant return on your investment in just a few years.

The GEA AddCool® system has undergone extensive trials at the GEA testing station in Søborg, Denmark. We’re happy to invite potential customers and other interested organizations to attend proof-of-concept demonstrations at the facility. The compact, skid-mounted AddCool® units are powered by electricity and can either be installed into a new crystallization plant or retrofitted into your existing setup without changing your crystallization process parameters or equipment.

Our GEA experts will work with you to configure an AddCool® system that fits in with your existing cold water production process and crystallization plant setup, and help you to maximize utility of the energy-efficient cooling and heating capacity that AddCool® offers, with minimal disruption.