Cleaning used to be entirely manual, requiring employees to climb inside mash tuns, wash backs and pot stills, which entailed significant safety risks. CIP (Cleaning In Place) was developed to address this, by providing automated ‘internal’ cleaning systems within mash tuns, wash backs and pot stills.
“CIP became more widely used in the early 1990s, and it’s standard practise to include CIP in new distillery equipment, though it can also be retro-fitted in older equipment. The cost of CIP can be anything from three to five per cent of the total cost of new build equipment dependant on size, though retro-fitting can be more expensive,” says Richard Forsyth, chairman of Forsyths, which provides design, build, installation and maintenance services.
Mash tuns require two cleaning systems, one above and one below the drainage plates at the base.
“The interior surface of the mash tun is cleaned once a week using hot water sprayed from nozzles positioned in the tun. This is a 45 minute cycle which also cleans the rake arms,” says Mickey Heads, Ardbeg’s distillery manager.
Drainage plates act as a ‘sieve’ when the wort (ie. sugary liquid) drains through them, and so are prone to being blocked by barley fragments, particularly husk.
“After every mash numerous nozzles beneath the drainage plates direct water at 85 degrees centigrade through the drainage slots, to dislodge any husks and finer remnants. This ensures the drainage works properly, otherwise the rate of drainage, and efficiency would be compromised. The cleaning cycle takes three to four minutes, followed by time for the water to drain into the effluent tanks,” says Heads.
A mash tun left empty for a significant period, and then not thoroughly cleaned, also poses significant risks.
“Bugs attach themselves to the husk of the barley, while any detritus in the mash tun, including fatty acids that stick to surfaces, also harbours bacteria. This could lead to an infection, and potentially form butyric acid, which creates ‘baby sick’ notes. If this gets into the wort you can’t remove it through distillation,” says Stuart Robertson, Dalmore’s distillery manager.
Wash backs can also experience bacterial infection if not cleaned properly, which compromises fermentation. Bacteria competes with yeast for sugars in the wort, for example, but that’s not all.
“Bacteria can also infect the yeast cells, and when stressed in this way yeast can’t complete the fermentation process normally, which means you don’t end up with the usual profile in the wash, and distilling is all about consistency,” adds Mickey Heads.
Wash backs are either stainless steel or wooden, with stainless steel having a reputation for being easier to clean, though that doesn’t necessarily mean a different approach.
“Speyburn has wooden and stainless steel wash backs, with the same cleaning regime. Spray balls within the vessels emit water at high pressure that makes them rotate and provide 360 degree coverage. The water is around 80 degrees centigrade which kills everything. After 10 to 15 minutes of hot water, steam is introduced from the base of the wash back for a further 10 to 15 minutes, with the lid down. This happens after every fermentation, to prevent the risk of bacterial infection,” says Derek Sinclair, distilleries general manager, Inver House Distillers.
In a pot still it’s the heating element, such as coiled copper pipes through which steam is conducted, that’s the focus. Heating elements in the wash still (ie. the first distillation) require more frequent cleaning than the spirit still (second distillation). This is because wash contains residual sugars, dead yeast cells, fragments of barley, and fats, that bake onto the heating elements, and consequently reduce the transfer of heat to the liquid being distilled.
“You can achieve the usual character and quality if the heating elements have a baked on layer, but it slows down the process and means using more energy, increasing costs, and also the time required,” says Stuart Robertson.
Needless to say, CIP has this covered. “After each distillation in the wash still, nozzles positioned to clean the heating elements spray a mild caustic solution (ie. chemical cleaner) onto them. This is then rinsed off with water from the same nozzles, and takes about 10 minutes in total. Another water flush for a couple of minutes completes the cleaning cycle,” says Mickey Heads.
CIP can be operated in two ways. “Cleaning cycles using CIP can be programmed to take place automatically during the production process, which ensures the efficiency of the clean within a specified time, and that we don’t use more water than is needed for washing and rinsing. Alternatively, a technician can initiate each cleaning process from a control screen. In our distilleries we use both of these options,” says Alan Winchester, The Glenlivet master distiller at Chivas Brothers. Another consideration is the amount of time CIP can save compared to cleaning manually. “Cleaning probably takes up around five to six hours of each employee’s working day, and we have four employees on shift during each 24 hour period so it adds up to a significant amount of time. We’re thinking of installing CIP in the wash backs, which are manually cleaned, it’s a major investment for a distillery, but worth it in terms of man-hours saved,” says Stuart Robertson.