Pot still for whisky distillation
It looks like huge kettle and enables batch system distillation. High alcohol spirits distilled by pot still keeps material original flavor.
It is used for malt whisky, Cognac, Tequila, Shochu Otsu type and heavy rum. Malt whisky require twice or 3 times distillation by pot still.
Malt whisky distillation is done by copper made pot still. Because malt contains sulfur components which makes discomfort burn rubber smell and copper remove it from mash steam during distillation process.
On the other hands, pot still for other spirits is normally stainless one.
Distilleries control how much and what kind of flavor contents remain in distilled spirits by reflux phenomenon.
Reflux is "heated steam going back to liquid and falling back to pot during distillation".
Increasing reflux makes spirits more clear mild flavor and light smooth taste. Decreasing reflux makes spirits rich material grain flavor and powerful taste.
Pot still part design
Distillery controls reflux level by pot parts design.
Standard whisky pot still
Normally whisky distillery has 2 pot stills at least because they need wash still for 1st distillation and spirits still/raw wine still for 2nd distillation. Wash still is bigger than spirits still.
Most famous standard pot stills manufacture is Scotish company Forsyth but some pot still in Japanese whisky distillery are made by Japanese company Miyake Industries.
Molded pot still
Normally copper pot still for whisky was made by tapping process form sheet but there are only one pot still by molding process in the world. It was developed by Wakatsuru Shuzo and Oigo Seisakusho and it is operating at Saburomaru distillery.
Hybrid pot still
Normally whisky distillery has 2 pot stills at least because one is for 1st distillation (Wash still) and the other is 2nd distillation (Spirits still/Raw wine still). But some micro distillery has only one pot still.
This type distillery does both 1st and 2nd distillation by one pot still. So that these pot still is called hybrid pot still.
Most of hybrid pot stills for whisky are made by German company Arnold Holstein.
Stainless pot still
There are much more stainless pot still than copper pot still in Japan. Because traditional Japanese spirits (Shochu and Awamori) are made by stainless pot still.
Normally stainless pot still is not suitable for whisky because it can't remove sulfur compounds in malt during distillation. Sulfur compounds causes disconfort smell like burned rubber. Altough copper pot still can remove it.
Vacuum stainless pot still
Almost all rice whisky distilleries are using stainless pot still which they are using for Schochu. In deed, stainless pot still distillation of Shochu and rice whisky doesn't have any problem because fermentation is done by Koji enzyme instead of malt enzyme.
On the other hads, a few distilleries are producing whisky fermentated by malt enzyme by stainless pot still. As a theory, whisky could have sulfur smell however some of them are very smooth taste. It is probably made by vacuum type stainless pot still which was developed by Schochu and rice whisky distillery Kitaya.
Pot still manufactures
Distillery controls reflux level by pot parts design.
This scotish company was found in 1890. It is most famous whisky pot sill manufacture in the world today.
Many pot stills in Japan were also produced by Forsyths.
This is Japanese company was found in 1934. Their main business is bear production facility.
They started pot sill production after WW2 and Miyake is one of main pot sill producer for Japanese whisky today.
This Italian company was found in 1912.
They are producing mainly copper or stainless pot still.
This German company was found in 1958. They are producing small-middle size still system not only for whisky but also for many other spirits like Vodka, Rum, Gin, Tequila, Grappa, Brandy.
They are good at producing hybrid type pot still.
This Japanese company was found in 18th century. Actually it is copper casting company for Buddhist temple but they started pot still production with Saburomaru Distillery.
Column still for whisky distillation
It looks like chemical tank tower.
It enables multi step distillation in column(tower) as continuous line production. Alcohol distilled by column still is smooth flavor and clear taste.
Distillation of almost all grain whisky is done by column still.
Vodka, Base spirits of gin and liquor, Shochu Kou type, Marc and light rum are also made by Column still.
Inside of Column
There are many steps in column. Mash is injected in middle steps and flowing down to lower steps. There are many small porous on steps which steam pass through.
Mash on the step is heated by steam from lower step. Alcohol and water are evaporated from mash and going to upper steps. Steam heating mash is going back to liquid and falling down to mash
Due to above process, mash/liquid and steam in upper floor has higher alcohol than lower floor.
Coffey column still
First column still was developed in 1826 in Ireland by Robert Stein.
Aeneas Coffey developed improved column still "Coffey still" in Ireland and applied patent in 1830(Approved in 1831). But distilleries in Ireland were very conservative and stick to conventional pot still. Therefor he moved to England in 1835 and Coffey still became popular in 1840s for white spirits to make Gin.
Just 1 year after his death in 1852, blended whisky was approved and grain whisky made by Coffey still became main material of Scotch blended whisky. Blended scotch took market share from Irish single pot whisky made by traditional pot still.
There are only less than 10 column stills working today in the world and 2 of them are in Miyagikyo Nikka. There were one more coffey tye column still in Kawasaki distillery of Ocean group.
Super Arosupasu column still
There were several improved column still after Coffey still like Irguez type, Guillaume type and Grimma type however most remarkable is Arosupasu type by Usine de melle company in France in 1950. Improved Super Arospasu type was also developed in 1955.
It can remove fusel oil which makes uncomfortable flavor from spirits by Hydrolytic distillation. After Super Arospasu type, there were some improved type like decompression type, although Super Arospasu type is standard method of not only grain whisky but also world spirits today.
Suntory and Kirin chose this productive column still when they buit their new grain whisky distilleris(Chita and Fuji Gotenba) in 1973.
Takara group is also using it for Schocu and other spirits.