Here at InchDairnie we are always looking for different ways to reduce our carbon footprint. An opportunity presented itself last year when Rowan Davidson, a Masters in Engineering student from the University of Glasgow approached us with the possibility of doing a feasibility study, looking at the potential use of Heat Pumps in the distillery.
A distillery uses a lot of heating up and cooling down process steps and not all the cooling down process can be used by some of the heating up process. InchDairnie has been able to design in-heat recovery wherever possible, linking the cooling down with the heating up. Despite this, the distillery is still ‘rejecting’ some heat via a cooling tower to the atmosphere.
The distillation process requires heat to be put into the stills and the resulting vapour to be condensed by taking the same heat back out again. Both stills at InchDairnie have two condensers and both stills utilise Thermal Vapour Recompression (TVR) technology to recycle some, but not all of the heat back into the same still. On the wash still, the heat that is not recycled back into the still is condensed in the second condenser where the heat is used to heat up water for the mashing process. However, heat from the second condenser on the spirit still which also has the TVR technology installed cannot be utilised elsewhere in the process. This heat is sent to the cooling tower where it is rejected to the atmosphere.
Despite utilising the second condenser to the wash still to provide heat for the mashing process, some heat from the boiler is needed to top this up.
So, the concept was developed to try to use the rejected heat from the spirit still to replace the additional heat needed for the mashing process. This was where using the heat pump was considered.
What is a heat pump? Heat Pumps today are becoming common place to heat domestic properties where they take the warm air outside the house to heat up the inside of the house. A heat pump is a refrigerator but in reverse. However, these heat pumps work at relatively low temperatures while here at the distillery we want to take heat from hot water, 70oc and use it to generate steam.
The feasibility study showed that we could collect the heat turn it into steam and use it to eliminate all the additional energy required by the mashing plant. The full report is available here.
Our next step is to invite suppliers of high temperature heat pumps to provide us with a financial evaluation of the concept. When this work is complete, we will publish the data.