Saturday, 27 February 2016

Guinness’s Park Royal Brewery in 1949 – the brew house (part six)

Back in Guinness’s brewhouse. Looking at their refrigerators in ridiculous detail.

We seem to be jumping about a bit in terms of plant, because now we’re going back to the second phase of wort cooling, using refrigerators. And, no, they weren’t the same as a domestic fridge.

“The wort refrigerators are of the multi-plate type of standard pattern, arranged in six lines on the third floor of the fermenting house, each line consisting of two sections of 36 plates, arranged in passes of nine plates. The plates have a cooling surface of 5.5 sq. ft. each. Each line of two sections has a capacity of 60 barrels per hour, making 360 barrels per hour in all, which allows the worts to be cooled in about 10 hours.”
Journal of the Institute of Brewing Volume 55, Issue 5, 1949, page 283.

Remember that they brewed around 3,000 barrels a day. At 360 barrels an hour, I make that 8 hours to cool all a day’s brews. Which seems like an awfully long time. That must be one of the main reasons it took wort so long to get from the mash tun to fermenter.

“To avoid undue scale on the plates, the wort refrigerators are taken down three times a year and the plates dipped in a 26 per cent. solution of caustic soda, after which they are thoroughly brushed and washed. The cooling water services consist of direct water with a winter temperature of 50° F. and a summer temperature of up to 70° F., and artificially chilled water at 45° F., the latter being used in summer. The seasonal temperature ranges are as under:—


Direct Water cooling. Chilled water cooling.
Wort .. ° F. 175 to 78 78 to 55
Water .. ° F. 130 from 70 65 from 46
Water/Beer Ratio 1.6 1.5

Direct Water cooling.
Wort .. ° F. 176 to 66
Water .. ° F. 130 from 60
Water/Beer Ratio 1.5

Journal of the Institute of Brewing Volume 55, Issue 5, 1949, page 284.

I was struggling to understand that at first glance. Now I see what it means. In summer they first used water at its normal temperature, then used chilled water to drop it the last few degrees. Obviously you couldn’t get the wort cooler than the water cooling it. While in winter, when the water was cooler they didn’t bother with chilling.  In both summer and winter, the unchilled water rose in temperature to 130º F.

I’m struck by the difference in the temperature of the wort in winter and summer. It looks like they were pitching at 55º F. in the summer and 66º F. in the winter. That’s really unusual. Breweries usually pitched at the same temperature all year round. Then again, most breweries had fermenting vessels fitted with attemperators and could control the temperature of the fermenting wort. If you remember, Guinness’s didn’t have attemperators. Maybe that’s the reason for the different pitching temperatures.

For beer the Strength of Guinness, 55º F. is a very cool pitching temperature. Then again 66º F. is quite high. At most breweries, I’d expect it to be pitch at around 66º F. and hit a maximum of 68º F. to 70º F.

Confirmation that these were the pitching temperatures:

“From the wort refrigerators the wort runs down from the yeast troughs already referred to, to the fermenting tuns arranged on the floor below.”
Journal of the Institute of Brewing Volume 55, Issue 5, 1949, page 284.

The yeast troughs, you may recall, were where the wort was mixed with yeast before going into the fermenters.

Next we’ll be taking a close look at the fermenters themselves. 

1 comment:

StuartP said...

It's getting worse:-
Hot-side aeration
Slow wort cooling
Not controlling the fermentation temperature
No wonder their beer was terrible and no-one drank it.