Coolship
Coolship en Allagash (EE.UU.)
There are many misunderstandings about the use of a coolship, both in the past and the present. Hence this article.
In the distant past, every brewery had a coolship. After all, this was the only known way to cool the boiling wort to an acceptable temperature before taking further brewing steps.
Typically, it was a shallow vessel with cumbersome dimensions. It was often located under the roof. The wort stayed there for a while, being cooled by the draft blowing through the open windows next to the cooling vessel. in other words the cooling vessel made use of the natural conditions, i.e. the outside temperature. During the colder period in Europe, let's say September to April, the brewer was able to cool the wort with a boiling temperature of about 100°C to about 20°C within a reasonable time. When that temperature was reached, the wort could be transferred to the vats for fermentation.
In fact, the coolship fulfilled three functions:
Cool the wort
Aerate the wort
Separation/settlement of the trub (grain and other residues).
The breweries in those days only made top fermenting beer, and their coolships most of the time consisted of wood, with a wort depth of 4 to 8 cm. The richer guys could afford metal, mainly copper for good conductivity. Those metal ones have survived the ages, contrary to the wooden ones, such that we now think that all coolships always have been metal. Do note, some brewers sometimes even used two coolships to better separate the trub.
The danger was obviously that microflora from the environment (and the wood) could infect the wort, think ‘lambic’. And so the flora did contaminate. After all, it is a myth that brewing in early times only took place in those 'cold' months. Beer was brewed all year round, but the beer brewed in the warm months infected very quickly, so that it was drunk extremely young, sometimes after a few days.
In order to (try to) avert that danger, a different approach was sought. In the 19th century, a number of inventions appeared that limited the use of the coolship and the associated risks. However, all followed the same principle, interacting through a set of tubes of cold water, over which the boiling (or slightly cooled) wort ran. That cold water allowed faster cooling of the wort under reasonably hygienic conditions.
The first known 'inventor' is said to be the Frenchman Jean Baptiste Cellier-Blumenthal, well known in distillery circles, who settled in Koekelberg near Brussels and patented a beer cooler in the 1820s, which would have little to no commercial success. The breakthrough came with Frenchman Jean-Louis Baudelot who designed and patented his famous cooler in 1856 (some say 1859). In fact, it was a series of horizontal metal tubes connected at the ends to form one long continuous tube, with a large surface area. Cold water was passed through those pipes. The wort was poured into a gutter at the top, then ran vertically down that cold surface, where it was collected cool in a container at the bottom of the machine. From there it went to the fermenters.
That approach was quickly very successful. There were quite a few brewers who saw the Baudelot and thought it was a wonderful idea, after which they created and developed their own version. There were also some "inventors" who produced vertical versions of the horizontal cooler, but these often took up too much valuable floor space and were short-lived.
It must be said that the Baudelot cooler did not replace the cooling vessel, but complemented it. After all, a vertical cooler makes cooling and aeration possible, but does not allow the sedimentation of (grain) residues. The brewers thus continued to put the wort in the cooling vessel, where they allowed it to cool to 60-70°C before sending it to the Baudelot, where it cooled further to the desired temperature, usually between 20-25°C.
However, even the Baudelot cooler could not completely stop infections, because there was still a short period when the wort was exposed to the open air and the related microflora. That is why other solutions were sought in the twentieth century. These were found in modern plate heat exchangers, plate coolers, cooling coils, etc. These are very hygienic if well maintained, but only fulfill the cooling function, so no aeration and residue removal, which, if desired, must still be carried out separately.
But we'd be talking about the coolship. At many older breweries it has been removed or it only serves as a museum piece. However, there are still brewers who use it in their daily practice. Obviously, everyone will refer to the lambic brewers that still do (except for one, Mort Subite). At the same time, there are many craft breweries worldwide that have meanwhile installed one to make (extra) sour beer, think e.g. in the US Allagash, Beachwood Blendery, ….
Nevertheless, there are also others who use it to make 'normal', so non-sour beers. The first brewery where I saw it still in active use was the historic Uerige brewery in Düsseldorf, who pride themselves on their coolship, where they cool the wort for their Alt beers to approx. 55°C before it goes to their Baudelot. Completely according to the 19th century methodology. And recently I had the pleasure of seeing the cooling vessel at work at U Fleku, Prague's oldest brewery dating back to 1499. There the wort is cooled in the coolship to 60°C before being transferred to the plate heat exchanger. A beautiful sight. Nice detail: the brewery equipment is from Skoda (best known as a car manufacturer). Funny, isn't it?
In the meantime my good friend Markus Raupach told me that there are still more than a few breweries in Germany that continue to swear by the coolship. Such as Drei Kronen (Memmelsdorf) Höhn (Memmelsdorf), Brandholz (Melkendorf), Hoepfner (Karlsruhe), Mittenwalder Brauhaus, Prechtel (Uehlfeld), Gänstaller (Schnaid), Schumacher (Düsseldorf), as well as some breweries in Saxony and Thuringia. Furthermore, the brewing equipment manufacturer Kaspar Schulz still offers coolships. Nice proof that the coolship for 'normal' beers has certainly not yet been fully written off.
One question I regularly get when talking about coolships, is how long the wort has to stay in that coolship. The main part of the answer is clearly that it is the time to get to the desired (lower) temperature. How fast that occurs depends on the surface, i.e. the bigger the surface that is exposed to the outside air, the quicker the wort will cool down. You could formulate it such that that the cooling rate is largely in the hands of the brewer: it is a function of hectoliter wort/m² coolship. The brewers of old definitely knew this well, see above with shallow wort levels of 4 to 8 cm.
Finally, a weird detail. City brewery 't Koelschip operates in Ostend, Belgium. Nice name, but they don't have a coolship. How crazy can it get.
https://www.uerige.de/en/brewery/
El Coolship de U Fleku en República Checa