Saturday, 16 January 2016

Guinness’s Park Royal Brewery in 1949 – the malt store (part two)

I bet you’ve been eagerly awaiting this second part on the malt store in Park Royal. I’ve barely been able to sleep, myself.

This all sounds rather modern, though I guess today it would all be computer-controlled. This must have been some sort of electro-mechanical system.

“The whole system is automatically sequence controlled through a control board on which the operator plugs in the particular screening system he wishes to use and the inter-connecting elevators and belts. The two delivery belts from the malt store to the brewhouse have a capacity of about 200 quarters per hour each, which allows a day's malt to be transferred in three to four hours on one belt. Briefly, the malt is received in sacks either by road or rail, emptied into the intake hoppers on the ground floor from which it is elevated to the receiver at the top of the system on the sixth floor and weighed. The bottom hopper of the weigher is arranged to divide the malt automatically into two equal streams which then pass over the magnetic separators to the malt screening cylinders below. Each intake unit has two banks of wire-mesh screens through which the grain passes in series.”
Journal of the Institute of Brewing Volume 55, Issue 5, 1949, page 280.

Now isn’t that handy? They’ve pretty much told me how much they brewed each day. They were using 600-800 quarters a day and we know that they brewed about 5.25 barrels per quarter of malt. Which means they brewed between 3,100 and 4,200 barrels per day. Brewing 6 days a week, that adds up to around a million barrels annually.

I’m surprised that malt was still arriving in sacks rather than in bulk. It seems an inefficient way of delivering such large quantities.

Screening malt before it got to the mill was vital. It always seems to have been delivered with some crap in it: stones, nails and all sorts of crap. Some breweries had magnets for removing metal objects. But you can see that screening wasn’t just about removing foreign objects, but also about removing grains of the wrong size.

“The first bank is located on the fourth floor of the malt store and consists of twin screens separating out culms and large and small grains, the overtails being stones and large foreign material. The second bank arranged on the third floor separates out any culms which have passed the first screen and small and broken grains, the overtails being the large grains. It is necessary to separate the small grains which will pass an 86 mesh (0-091 in.) as they require a special setting of the mill rolls to give the required grist. Large malt is overtaxed and passed through an aspirator connected to a suction fan which draws off light and diseased grain.”
Journal of the Institute of Brewing Volume 55, Issue 5, 1949, page 280.

The blades of the malt mill were set precisely. Brewers wanted their grains crushed, but not reduced to flour. (Well, most brewers didn’t. Those with a mash filter rather than a mash tun needed it ground very fine.) Which meant the grains all needed to be of a similar size.

I’ve no idea what “overtaxed” means in this context. Though blowing away light grains is quite clever.

“Large malt from the final screening section passes to a weigher and afterwards to an elevator which takes it to the top of the house and to the system of eight transfer conveyors arranged above the silos from where it is discharged from travelling carriages to any silo. The small grain plant removes any remaining culms after which the malt passes through an aspirator which draws off light and diseased grain. There are no overtails from this machine as all large impurities have already been removed. The thin malt from the aspirator is delivered by belt conveyor to two Carter disc separators which remove small round seeds, half grains, etc., from the malt, sound malt passing to the weigher and elevator for delivery to silo. The malt is drawn off from the silo bottom through valves and chutes to a system of 16 cross-belt conveyors below, and thence to transfer conveyors and to large automatic weighing machines, elevators and transfer belts to the brew house.”
Journal of the Institute of Brewing Volume 55, Issue 5, 1949, page 280.

They certainly took screening seriously. Is that two or three times they screened the malt?

Next we’ll be entering the hop store.

1 comment:

Patterson said...

In my experience screening other stuff, you pretty much have to do at least a couple of rounds. If you start out trying to screen everything, you end up spending a ton of time clearing out clogs, so it tends to work better if you get bigger junk out of the way first and then getting a finer sort later.