MEETING OF THE LONDON SECTION HELD AT
THE HORSE SHOE HOTEL, TOTTENHAM COURT ROAD,
ON MONDAY, 10th JANUARY, 1949
The following paper was read and discussed:—
FAMOUS BREWERIES. 4.* PARK ROYAL BREWERY
(Messrs. Arthur Guinness, Son & Co., Ltd., London.)
By M. W. Plumpton, M.I.Mech.E., M.Inst.F.
An account of the plant available is given in some detail, its mode of operation being outlined with individual departments discussed independently. Attention is given to problems of sterilization of plant and of fuel economy.
The construction of Park Royal was an event in the history of English brewing in that it was the first time in this country that a large brewery had been built on a clear site—one might even say, a green field—with nearly 200 years’ experience of an existing brewery to draw upon and the difficulty overcome of starting up a completely new plant for a process which depends so much upon carefully conditioned vessels and other equipment.
The operations of the Company and the (For Parts 1, 2 and 3 see this Journ., 1043, 1, 106, 265.) Dublin Brewery are well known to the Brewing Industry, and as for some years it had been apparent that, since so large a proportion of the output from Dublin was being sent to England it would be economical to establish a brewery here for that trade, in 1933 it was decided to do so. Once the capacity of the English brewery had been determined by considerations of trade and distribution, the design of it was commenced and at the same time a survey made of probable sites.
The site selected was convenient to the Great Western Railway (now British Railways, Western Region) and the Grand Union Canal, and had excellent road connections, being adjacent to two of the main arterial roads in north-west London. The site was planned with a view to developing it on modern lines not only from the point of view of factory operational efficiency, but also to provide those amenities and facilities for the staff which have always been a feature of the Company’s activities. The area of the site selected was about 137 acres, the eastern portion of about 45 acres being allocated to the brewery proper and the remainder of the land north and west to playing fields, employees’ houses and other amenities. A feature of the site is the fall of the land contour from south to north, and the main brewery buildings were arranged with a view to the maximum use being made of this fall, the process flow following it as far as possible.
The brewery was designed for a normal production of 650,000 barrels per annum, with an overload production capacity of just over 1,000,000 barrels per annum with all plant in operation. The wisdom of this latter decision was manifest during the War, when with so many difficulties affecting materials, fuel, and transport from Eire, the ability of the Park Royal plant to produce this additional output was invaluable. Construction was commenced in November, 1933, and the first trial brew was run through in February, 1936. By the time War broke out in 1939 production had begun to approach the design figure as more and more plant was conditioned and brought into operation.
The buildings are generally designed and constructed in five large monolithic blocks on a line running roughly north to south, the front of the buildings presenting an attractive prospect from Western Avenue. The main buildings are supported on reinforced concrete piles 14 in. square varying in length from 35 ft. to 45 ft., each pile carrying a load of about 45 tons. The plant and machinery are carried on a braced steel-framed structure on the outside of which is a second framing anchored to the main frame supports and carrying the wall and brickwork panelling.
Water system.—The water distribution system is controlled from an intake and meter house through two 12-in. mains with two meters on each main, either meter being in use at any one time, the other being in reserve to ensure continuity of recording. On leaving the intake meter house the intake mains divide to form a ring main round the whole brewery, secondary feeder mains being tapped off to each department and the control valves being so arranged that full water requirements can be fed through either side of the ring main. The intake system is designed for an ultimate capacity of 1½ million gallons per day, and the present daily average maximum is about 750,000 gallons.
The heaviest user in the brewery is naturally the refrigerating plant, which in the summer months accounts for a maximum demand of up to 40,000 gallons per hour for the condenser cooling water. This water leaves the refrigerating plant condensers at about 85° F. and is discharged to overhead receivers in the brewhouse liquor system, any excess to holding capacity overflowing to two compounding reservoirs each of 250,000 gallons storage capacity. The reservoir water is pumped through a secondary ring main of 12 in. bore round the brewery, supplying Power Station services such as turbine condenser cooling water, oil cooler cooling water, boiler make-up and general rough washing services throughout the brewery. In terms of the ratio water/beer, the brewery consumption is of the order of 6 : 1 in summer, and 5 : 1 in winter.
From the point of view of continuity of supply the system has proved most satisfactory in use, but in view of present-day trends in water conservation and fuel economy, the possibilities and economies of using forced draught water-cooling towers for the refrigerating plant condenser cooling water and the steam turbine condenser cooling water are being considered. With a forced-draught cooling tower the cooling water could be re-circulated over the tower, thus saving the continuous intake at present necessary.
The malt store.—As constructed, the malt store can hold some 125,000 quarters, using both the main and auxiliary silos, the latter being in the inter-spaces between the main circular silos.
The malt store building is about 100 ft. high, the silos being of reinforced concrete masked by brickwork panelling. There are 127 silos each 12 ft. diameter by 65 ft. deep and holding approximately 760 quarters each, and there are 105 inter-space silos, with capacity varying from 130 to 165 quarters. Particular interest attaches to the construction of the reinforced concrete silos in the malt store, as they were among the first to be built in this country on the moving form principle with the concrete being continuously poured. The complete structure was erected in 13 days, the average speed of the erection being 5 ft. per day. In this method of construction, timber formers are built to the size and shape of the silos and lifted slowly by jacks as the concrete is continuously poured. It ensures not only rapidity of erection, but also a continuous smooth surface free from any joints which might arise from different setting consistencies of concrete inevitable in the fixed shuttering and batch pouring system.
The intake system had to be designed to receive by road or rail five different grades of malt simultaneously from different sources of supply, and to keep them separate through the screens and ultimately to the storage silos. To allow of this being done, the intake system was arranged in five separate units, each having a capacity of 250 quarters per hour and consisting of:—intake elevators; weighing machines before and after screening; magnetic separators; wire cylinder screens for cleaning and grading; suction filter dust collecting plant; and delivery elevators. Malt can be taken in at any unit, to be cleaned, screened and weighed, after which it is delivered to any one of the storage silos by means of the bucket elevators and the belt conveyor system. The stored malt can be turned over or recleaned whenever necessary. Similarly, malt can be drawn from any silo, to be weighed and passed over to the brewhouse mills.
The wire-mesh screens are constructed of 18 s.w.g. wire, the spacings for the various screenings being as under:—
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.
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.
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.
The silos were completed in October, 1935, and by February, 1936, it was necessary to provide storage capacity at Park Royal for incoming malt. As this was the time of the year with high humidity and as malt cannot be stored in damp silos, some means of quickly drying out these large circular silos had to be adopted. The conclusion reached at the end of various tests was that malt placed in a silo which had been heated would not absorb as much moisture as a non-heated silo if the silo was filled (and kept full) as soon as possible after drying had been stopped. To dry the silos artificially, large electric heaters of 10 kw. capacity were lowered into them and left there for 10 days, the heaters being raised gradually through the full height of the silo over the period. The outlet valve at the bottom was opened and grids were placed over the inlet opening at the top so that a current of dry, warm air was passing through the silos continuously.
The Hop Stores.—There are six hop stores with a total storage capacity of 050 tons. Each is a steel-framed, brick-paneled building, the steel stanchions being encased in concrete with chamfered corners to prevent damage to the hop bales, the floors of the stores being covered in hard-wood blocks laid on the concrete. These stores were designed to provide conditions necessary for satisfactory storage of hops, i.e. cool and dark buildings with a minimum movement of air. Each store is about 23 ft. high by 130 ft. long by 60 ft. wide, and each floor is designed for a load of 2½ cwts. per sq. ft.
The hop bales, handled into and out of the store by bale elevators, are stacked up to 18 ft. high with 18-in. walk-ways between, which brings them within about 2 ft. of the top of the store. Stacking is carried out by means of an “iron man,” an electrically operated lifting jib on a travelling platform. Although this has proved satisfactory, in future we would probably be favourably inclined towards an overhead travelling crane with the lifting carriage “nested” inside the crane frame to reduce head clearance.
Experience up to the time of designing Park Royal indicated that there was no marked economic advantage in artificially cooled hop storage, as the risk of possible deterioration of the hops due to temperature rise in a hot summer was more than out weighed by the heavy capital cost of the cooling plant. Consideration of the problem today and the relative costs might well decide in favour of the artificially cooled store.
The Brew House.—The brew house, designed for a nominal output of 3,000 barrels per day, is arranged on the infusion method of mashing, the main plant consisting of six mash tuns arranged in line on the south side of the brew house, with four boiling coppers in line on the north side. Each brew requires about 20 hours to complete from the commencement of the mash to the running of the last worts to the fermenting house, which permits of only one brew per day.
Normally, the six mash tuns are worked five days out seven, leaving two days for maintenance and adjustments, although during the war, they were worked 13 days out of 14 over long periods. This resulted in a heavy deferred maintenance programme to be dealt with after the war and which is only now nearing completion.
Before dealing with the plant in detail, perhaps a brief description of the operations in the brewhouse will be of interest. Malt is transferred from the malt store by belt and delivered into a chain-link conveyor running above the six mash tuns. Each mash tun is a unit complete with its own weighing machine, whole malt hopper, malt mill, grist hopper and Steele’s masher. The chain-link conveyor delivers the malt to the automatic weighing machine, the malt passing over a magnetic separator for removing pieces of iron and steel. From the automatic weigher, the malt is fed into a malt hopper large enough to take the requirements for one day’s brew for one mash tun. Below the malt hopper is arranged the malt mill delivering the ground into the grist hopper below. The grist is fed into a Steele’s masher, where it is mixed with the mashing liquor before being fed into the mash tun.
The worts are run off from the mash tun from underneath the false bottom plate and delivered to the underback from where wort pumps deliver it either to the coppers, or if no copper is available, to the upperbacks. After the addition of hops and the usual boiling off in the copper, it is struck off into the hop back from where the worts are pumped up to wort coolers arranged at the top of the building. After the usual standing time, the worts are run down to the fermenting house.
The six malt mills are of the two-high four roller type, each having a capacity of 30 quarters per hour. Each of the six mash tuns, designed for a mash of 110 quarters, is a circular cast-iron unit 20 ft. in diameter and about 7 ft. deep, the lower portion of the tun being insulated with plastic magnesia 2½ in. thick. The mash tun covers are of copper with the usual balance-weight lifting gear. The false bottom plates are of gunmetal with 22 s.w.g. slots, i.e. 0-028 in. wide. These plates are regularly cleaned about every four months with a hot caustic soda solution. The liquor space below the false bottom plates is 2½ in. At present, the bottom of the mash tun is cleaned by lifting all false bottom plates which involves a considerable amount of labour, but the fitting of a pressure nozzle cleaning system is being considered, which will reduce the frequency of the laborious lifting and replacing of the false bottom plates from being a daily routine, to perhaps a weekly one, or longer. Each mash tun has its own independent geared drive unit driven by a 10 h.p. motor and provision is made for coupling up the drive units of adjacent mash tuns by means of an extension shaft should there be a prolonged failure on a driving motor during the mash. The sparge arms are driven through a unit gearbox.
There are four wort coppers each with a holding capacity of 650 barrels. They are designed for pressure boiling at about 1½ Ib. p.s.i.g., giving a wort boiling temperature of about 216° F. The coppers are steam heated, being fitted with a six-wing vertical tubular heater having a heating surface of 176 sq. ft. and a five-loop heating coil with a surface of 160 sq. ft. arranged at the bottom of the copper. Steam is supplied at a pressure of 100 p.s.i.g., being reduced steam from the high-pressure steam lines. Each copper heater unit is capable of heating up a full copper in 1½ hours, and is capable of boiling off a maximum of 30 barrels per hour. Steam consumption is of the order of 9,000 lb. of steam per hour on the maximum duty. The copper is fitted with the usual pressure control and vacuum breaking and striking-off valves.
Originally the copper domes were bare copper in accordance with general brewery practice, but during the war the domes were lagged with 2½ in. magnesia with a saving in fuel of approximately 150 tons of coal per annum.
At the time Park Royal was being designed, the coppers in the Dublin brewery were coal fired with the exception of one which had been fitted with a steam heater for experimental purposes. From the brewers’ point of view, brewer colleagues appear to be quite satisfied with the result of steam heating—at least they have not yet asked for the steam heaters to be taken out in order to revert to coal or oil firing.
The vapour from boiling off is led through a lagged vapour main to jet condensers, specially designed for the purpose, and the cooling water is normally that returning from the wort refrigerators at a temperature of 130° F., which is just below the critical temperature for the deposition of the temporary salts. If, however, boiling off is taking place at a time when the wort refrigerators are not in use, direct cold water is used. In either case, the supply can be regulated automatically to give the condensate a temperature of 205° F., or the condensate re-circulated over the condenser to raise its temperature. The condensate is run down to the brewhouse low receivers for use in the brewhouse liquor system. Each copper has its unit condenser, which can deal with the maximum rate of reduction of 30 barrels per hour. The jet condenser is a simple and less costly plant than the more usual surface condenser, but it can only be used where a use can be made for the mixture of cooling water and condensed steam, i.e. distilled water. A brewery, of course, can make good use of such a supply of hot water.
The factors determining design are quantity and temperature of the cooling water available; the quantity and temperature of the steam or vapour to be condensed and the temperature of the condensate required, the latter being variable depending upon the amount of cooling water used or available. Conserving the heat of the copper reduction vapour in the way adopted saves approximately 750 tons of coal per annum.
There are two hop backs each of 800 barrels capacity of more or less orthodox design in that they are circular vessels of about 26 ft. 6 in. in diameter and 9 ft. deep, constructed in copper bearing steel to resist corrosion and the usual gun-metal false bottom plates, the slots being 19 s.w.g. i.e. 0.040 in. The hop backs have copper domes with a chimney taken up through the roof for disposing of the vapour to outside the brew house. Disposal of the hop-back vapour in this way appreciably reduces the maintenance of the building steel work, etc. Perhaps an interesting feature is that the hop backs are fitted with revolving rakes for putting out the spent hops. A small dip of weak worts is put into the vessel, the rakes revolved to mix thoroughly the content, and then the hop outlet is opened to a centrifugal “free flow” pump which pumps the spent hops over to the by-products department for draining and drying. The same pumping system is used for returning hops to copper for alternate boilings. The hopped wort from the hop backs is pumped up to the wort coolers which are large open vessels about 26 ft. X 24 ft. and 6 ft. deep, constructed in copper bearing mild steel and located on the top floor of the brewhouse. They are open to the atmosphere. The wort lies here where atmospheric cooling is allowed to lower the temperature to 176° F., which ensures that the temperature, when running down, does not fall below a safe figure. The wort is discharged into the wort coolers over aeration hoods.
Regarding liquor storage in the brewhouse, there is a bank of three high receivers at the top of the house for holding liquor at 205° F. Each vessel has a capacity of 500 barrels. Another high receiver is isolated for taking the hot return refrigerator water from the wort refrigerators in the fermenting house. Below the high receivers there are five 500 barrel low receivers taking the condensate from the jet condensers and the weak wort return from the draining of the spent grains and hops.
The total liquor storage capacity of the brewhouse is about 5,000 barrels, i.e. about 1.6 times the average brew. For heating up, the liquor is circulated from the low receivers through tubular steam heaters and thence to the high receivers, although either high or low receivers can be circulated through the heaters if necessary. There are three tubular heaters each capable of heating up 400 barrels of water per hour from 130° F. to 210° F. when supplied with steam at 27 lb. p.s.i.g.
The inside walls of the brew house are finished in white glazed hollow bricks to give a good surface for cleaning and to provide reflected light and a degree of insulation.
The Fermenting House.—This had to be designed for continuous daily brewings of 3,000 barrels per day. After the appropriate stand in the wort coolers, the wort is run down by gravity through a 5-in. bore main at a rate of approximately 340/400 barrels per hour to centrifugal pumps which pass the wort through a battery of plate-type refrigerators on the third floor of the fermenting house, where it is cooled to the required temperature. On its way to the fermenting tun, the wort is led to glass-lined troughs below the store, or pitching yeast presses, where the required weight of yeast is dropped into the flowing wort prior to its discharge into the fermenting tuns.
There are five 1,260 barrel tuns and six 630 barrel tuns, making a total of 11 in all. This capacity allows three brews to be accommodated simultaneously in the house and still have available one of each size for maintenance and Excise regauging. There are no attemperating coils in the fermenting tuns.
About 12 hours after the tun is full a certain quantity of gyle is drawn off to storage tanks and kept at a temperature of 40° F. by circulation through plate-type chillers cooled by brine at 25° F. When the desired fall in gravity has been attained, which is usually in about 65 hours, the tonnage is started and the beer is pumped up to the skimmers located on the three top floors of the fermenting house. Originally, the skimmers were fitted with attemperating coils for checking fermentation, but in recent years these have been removed as part of a “cleaning up” programme, and the skimmers now really serve the purpose of auxiliary fermenting tuns, the final cooling being carried out in a battery of plate-type referigerators very similar to the wort refrigerators. The beer is in the skimmer about 24 hours, during which time up to six yeast crops are skimmed off at various intervals, the store or pitching yeast usually being taken from the earlier skimmings. Immediately after the final.yeast skimmings, the beer is pumped from the skimmers through the beer refrigerators and run down to the storage vats in the vathouse.
The wort refrigerators are of the multiplate 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.
All pumps, both wort and water, are of the centrifugal moderate-speed type with variable speed D.C. motors for regulation and temperature control as may be necessary, the pumps being designed with a characteristic curve ensuring that the discharge pressure does not exceed 35 Ib. p.s.i.g. in order to avoid trouble with the plate joints.
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:—
From the wort refrigerators the wort runs down from the yeast troughs already referred to, to the fermenting tuns arranged on the floor below.
The tuns are of the totally-enclosed type and are constructed in Kauri pine, selected for its very well-known properties of hardness and smooth grain and low coefficient of heat conduction, the large ones being of 1,260 barrel capacity and are 28 ft. long x 26 ft. wide x 20 ft. deep. The small tuns are of 630 barrel capacity; they are 28 ft. long x 13 ft. wide x 20 ft. deep, the liquor dip in each case being 14 ft. 6 in. The ceiling of these vessels is formed by the reinforced concrete floor above, the underside of which is panelled in white glazed tiles.
No provision is made for the collection of CO2 gas, but the gas flows over and through ports below the door sill to a gas trunking system connecting the fans which discharge the gas to atmosphere over the fermenting house roof. For removal of gas after tunnage, portable reinforced rubber pipes of 6 in. diameter and long enough to reach the bottom of the tun are connected up to the gas trunking system with quick bayonet fastenings. A tun can be freed of gas within half an hour to enable men to enter for washing down. No detergents are used in washing.
It may be mentioned that difficulty has been experienced in recent years in these days of low gravities and their attendant troubles, in keeping the surface of the timber bacteriologically clean, and to overcome this it has been decided to line them with sheet metal. The first choice was stainless steel, but owing to the prolonged delivery dates and last, but not least, the very heavy cost involved, aluminium has been adopted. The lining will be of 6 gauge thick aluminium sheet 99.5 per cent, purity to B.S.S. A3 of welded construction with felt and bitumen backing, and the necessary inlet and outlet connections will all be “cleaned up” to remove, as far as possible, all corners where infection could possibly find a lodging.
Originally, the tuns were roused with mechanical power-driven paddles arranged on the floor of the tun, but it was almost impossible to keep these even reasonably clean and they are now being replaced by compressed-air rousers, which consist of a venturi tube in aluminium in the throat of which is arranged a ¾ in. nozzle. The potential energy of the compressed air is converted to kinetic energy in the venturi, thus inducing movement of the liquor mass. The unit is small and compact and readily removable for cleaning and is arranged on the floor of the tun. The air rouser gives excellent results, promoting vigorous circulation which can be easily controlled by the air valve, the operating pressure of the air being about 15.6 p.s.i.g.
As the top fermentation process is used, means are provided for the mechanical removal of yeast from the beer surface. This is done in skimmer, of which there are 24 arranged on the three top floors of the fermenting house. The skimmers are large shallow cast-iron vessels each of 425 barrels holding capacity and are 57 ft. 8 in. long by 12 ft. wide and 4 ft. 3½ in. deep. When the gravity in the fermenting tun has reached the pre-determined figure above primary gravity, the beer is pumped to the overhead skimmers. Yeast is collected by the dropping system, the skimmers being worked in vertical banks of three vessels.
Of the eight skimmers occupied by a brew, one is a balance vessel fitted with the orthodox parachute or movable yeast hopper. Ordinary skimmers have a yeast trough on the end of the vessel, and the yeast is manually skimmed to the trough and dropped into the yeast collecting vessels below each bank of three skimmers. Each skimmer yeast trough is fitted with two outlet chutes and a portable plug which allows the yeast from the skimmers to be passed down selected chutes to the yeast collecting vessels below. In this way a yeast crop for pitching can be kept isolated.
There are two stainless-steel enclosed cylindrical yeast collecting vessels each of 200 cu. ft. capacity, i.e. 400 cu. ft. for three skimmers holding some 1,275 barrels of beer. These collecting vessels are fitted with internal power-driven fob breakers for degassing the yeast by cutting it down as it enters the vessel. Continuous yeast collection can be carried out as one collecting vessel can be blown to the yeast presses while the other is being filled. The capacity of each pair of yeast collecting vessels is sufficient to take about 65 per cent, of the total yeast from three skimmers, as the yeast “broken down” by the fob breakers is about the same density as ordinary liquid yeast.
As there are eight banks of skimmers there are 16 yeast collecting vessels in all, arranged in two aisles one on each side of the house. The vessels are equipped for pressure evacuation by air at 45 Ib. p.s.i.g., the yeast being blown to filter-cloth yeast presses. There are two blowing mains, one for “pitching,” i.e. yeast used in the brewing process, and the other for surplus yeast. This ensures that a selected “pitching” crop can be isolated from collection in skimmer to pressing. The yeast-blowing mains are of tinned copper with rubber diaphragm valves and flexible rubber connections for connecting one vessel to either “pitching” or surplus yeast lines. The yeast vessels are scalded out with hot water at 190° F. after each brew.
The yeast presses are of the standard filter-cloth type cooled with chilled water at 45° F., there being one bank of four 9 cwt. presses for store or “pitching” yeast, this quantity being sufficient for two brews, which is necessary to maintain brewing over holiday week-ends. For the surplus yeast, there are seven 16 cwt. presses cooled with chilled water. All the above weights are of pressed yeast. The barm beer from the press is collected in welded mild-steel enclosed collecting vessels. All the bottoms from the fermenting tuns and the fermenting house vessels are collected in stainless-steel enclosed cylindrical-bottomed vessels and blown to the surplus yeast presses.
The Vat House.—From the beer refrigerators in the fermenting house the beer is run down by gravity to the storage vats in the storage vat house, which is virtually a storage cellar, and to prevent any undue rise in temperature the building is lined with special insulation bricks of standard brick size. The flat concrete roof is asphalted and covered with white spar chippings in bitumen to reflect the heat of the sun. There are no windows and results have generally been most satisfactory, the temperature of the liquor in vat being practically unaffected in mid-summer. The vats are constructed of oak and hooped with copper bearing mild steel, there being 24 large vats, each with a capacity of 1,150 barrels, and eight smaller ones having a capacity of 870 barrels each.
The pipe lines, as in the fermenting house, are of tinned copper and there is nothing of particular interest in this building excepting the large positive displacement pumps which are used for transferring the beer from the storage vat house to the elevated racking vats. The choice of positive displacement pumps was determined by the variation in pumping head arising from the storage vats being 20 ft. deep and the racking vats some 18 ft. deep arranged above them, the transference from full to empty vats involving a difference in head beyond the characteristic curve of the standard centrifugal pump when maintaining the necessary output.
Cask Cleansing and Racking Shed.—The cask cleansing and racking shed is laid out and planned to take advantage of the natural fall of the ground from south to north with the result that casks will roll of their own volition from one machine to another throughout the length of the cleansing and racking bank.
There are five cleansing lines, each capable of handling 100 hogsheads per hour consisting of:— (a) An external washer with clamping brushes, the casks being mechanically revolved. (b) Internal washer of the revolving nozzle type supplied with high-pressure water at 200 p.s.i.g. at 200° F. (c) A bank of 10 steaming nozzles fed with steam at 5 p.s.i.g. for three minutes per cask.
Common to the cleansing lines is a cooling floor where the steamed casks stand to “cool off” for 12 hours before passing forward to the rackers. There are four racking machines of standard gravity type, each capable of dealing with 140 hogshead per hour. For checking the capacity of casks coming from the hoop drivers there are two cask-measuring machines which check the net holding capacity by weight of water and which have a dial on which is indicated the variation from the standard weight. The daily routine is that the empty casks are received on the “high” end of the bank where defective hoops are dealt with on the hoop drivers and all casks pass through the line of washing machines in sequence.
The necessary hot water for internal cask cleaning nozzles is provided by two steamheated water heaters, the hot water discharged from the internal-nozzle cleaning machines being collected and re-used on the outside cask washers, thus affecting a useful economy in heat.
The Cooperage Shops.—The cooperage shops are located adjacent to the cask cleansing shed, the machinery and equipment being of more or less standard type. The shops are laid out to cope with all repairs and new casks required for the Park Royal trade.
Pipe Lines and Valves.—A programme of simplification of piping circuits on the liquor side of the brewery mains system with a view to attaining more sterile conditions is being carried out; a few remarks on this may be of interest. Regarding the material for mains for carrying wort, beer and yeast, tinned copper has been found to be quite satisfactory over a long period, and the conclusion was reached that there were no economic or practical advantages to be obtained by changing over to stainless steel or aluminium at this stage, particularly as the elimination of a large quantity of copper main left ample stocks for realigning the various runs of mains. Stainless steel offered advantages from the point of view of smooth bores and reduced corrosion rate, but it is susceptible to the heat treatment necessary in welding and it is much more difficult to work to shape than copper. More or less the same arguments apply to aluminium.
The question of joints is an important one in brewery beer circuits, and we are dispensing as far as is practically possible with the flange joint and rubber insertion ring, the latter being a serious source of infection trouble, as the rubber ring squeezes out into the bore of the main, forming pockets of infection. As far as possible, welded circumferential joints will be used and flanged joints will be used only at terminal points and valve connections. Welding methods today have reached very high standards by the adoption of the Argon-Arc, atomic-hydrogen and other methods, and these systems of welding in intelligent hands can produce good internal surfaces and also oxidation-free welds. It is necessary, of course, that the welder for this class of work is an intelligent man who has received some special training in the work.
For flanged joints it is proposed to adopt bolted gun-metal flanges brazed to the copper tube with serrated joint rings of phosphor bronze, more or less in accordance with high pressure steam joint practice. The advantage of the serrated metal ring joint is that it gives a metal-to-metal contact and maintains continuity of the bore and gets rid of the objectionable rubber ring.
It is proposed to sterilize all mains with low-pressure steam, which will subject the pipe lines to expansion and contraction stresses which will be met by expansion bends and flexible hangers again on the lines of steam pipe practice. When the mains are being hung they will be anchored at fixed points and closure spaces left equal to half the calculated expansion movement and the mains pulled up cold.
On the original installation pipe bores were fixed to give an average velocity of 4-5 ft. per sec. on a maximum flow, but practice shows that the mains were frequently running only half-bore and that as a result, a drying-out process was occurring, leaving a deposit on the walls of the pipe. To overcome this, the velocity will be increased to 8-10 ft. per sec, which will promote turbulent flow and also, it is hoped, have a slight scouring effect which should prevent, or at least appreciably minimize, deposition. The mains will be hung to definite falls for drainage purposes which as far as possible will not be more than 1 in 40.
Like most breweries, we originally installed the expensive and heavy gun-metal plug cock on beer and yeast lines, etc., but it has been found in practice to be a veritable bug bear in all senses of the word. Furthermore, there was endless trouble in maintaining tight plugs when we commenced scalding mains owing to expansion and contraction. It has been decided to replace all plug cocks and gate valves throughout the brewery by the rubber diaphragm type of valve, which in addition to being much cheaper, presents no difficulty in maintaining tightness under intermittent high temperature conditions, and is easily maintained, the replacing of the diaphragms being almost a matter of minutes. On beer lines the diaphragms will be replaced after a fixed period of service which will be well within the useful life of the diaphragms. A modification of the standard rubber diaphragm valve has been designed which will obviate the pockets of liquor in the “dead ends” of pipe junctions and bifurcations, which are a frequent source of infection and loss of beer.
The problems of sterilizing mains can be resolved into (a) the positive removal of all deposits; (b) the destruction of all bacteria. The former can be carried out by the simple expedient of flushing out and the second by the application of heat at a “killing” temperature over a definite period of time, or by chemicals. It has been decided to adopt a combination of flushing out with cold water followed by low-pressure steam sterilizing, the latter being carried out on a definite temperature-time basis to ensure that the pipe and valve metal will be maintained at not less than 180° F. for 10 minutes.
The decision to adopt steaming in preference to scalding by hot water was taken for economy of heat and ease of application. When using hot water for sterilization purposes, it is necessary to maintain a flow to make up the heat loss occasioned by radiation and convection, and furthermore, the flushing must be vigorous enough, which means velocity and quantity, to remove deposits. This practice involves a very high consumption of hot water and is extremely wasteful of heat. With low-pressure steaming there is no need to have a flow of steam through the pipe owing to the large latent heat content of the steam, which means that the steam can give up heat without a drop in temperature. One charging of the main is usually sufficient to maintain the required temperature over the required period.
Steam and Power.—The whole of the steam and electrical requirements are generated in a central power plant, the decision to adopt private generation being largely due to the process steam requirements of the brewery. As is well known, electric power generated on back-pressure turbo-generators is substantially cheaper than power generated on the condensing steam turbo-alternators of the large grid stations, owing to the loss of latent heat in the condensers to the river cooling water. The back-pressure power generation system has an average thermal efficiency ranging from 50 to 70 per cent., while a similar figure for the large grid power stations is of the order of 27 per cent.
The power station plant was, therefore, designed to correlate the power and process steam demands, provision being made for the utilization of surplus back-pressure steam in a condensing turbo-generator. The station is designed to be completely independent of any external services beyond those of water and fuel. It is self-contained in its own steel framed and brick-panelled building with boiler and turbine-houses and basements and annexes for the auxiliaries.
Coal can be delivered by rail, road or canal. It is discharged into the boot of a gravity bucket-conveyor which delivers it to the coal bunkers which have a capacity of 900 tons, or three weeks’ supply. Oil fuel is delivered by road and stored in oil-fuel storage tanks with a holding capacity equivalent to four weeks’ supply; the tank farm being remote from the boiler-house, the oil is pumped across to service tanks near the boiler-house. The normal maximum demand on the boiler-house is 70,000 Ib. of steam per hour.
In the boiler-house are four water-tube boilers each with an economical rating of 30,000 lb. of steam per hour at 200 Ib. p.s.i.g. and 600° F. All four of the boiler units were originally coal-fired, with mechanical stokers, but since the fuel crisis of the 1946-47 winter, two of the boilers have been converted to oil fuel firing. This means that total steam requirements can be met by either coal or oil.
Each boiler is fitted with its individual vertical tube economizer, forced-draught and induced-draught fans and cyclone dust collection equipment. There are three electrically driven feed pumps, and one steam turbine driven pump for emergency purposes. The feed-water system incorporates combined deaerators and feed heaters which deal with the water on its way to the economizer. The make-up of the feed water is about 25 per cent, of the total required as 75 per cent, of the condensate is returned from the brewery. Make-up is taken from the secondary circuits ex-reservoir and treated in a lime-and-soda water softening plant before it enters the feed system.
The main generating plant consists of four geared turbo-generators, three of which (2-500 k.w. and 1-250 k.w.) are back-pressure units which take steam direct from the boilers at 200 lb. p.s.i.g., and exhaust to the brewery process-steam mains at 30/6. p.s.i.g. The back-pressure machines all have an overload capacity of 25 per cent, for two hours. The fourth turbo-generator (250 k.w.) acts as a balance between the power and process-steam demands, taking surplus exhaust steam and expanding this down to 28 in. vacuum. The redress of the balance in the opposite direction is obtained by duplicated reducing valves which come into operation automatically if the process-steam pressure is reduced to 27 Ib. p.s.i.g. Under these conditions the reducing valves admit reduced high-pressure steam to the process mains through de-superheaters.
The generating system is direct current 3-wire 425 volts between the outer conductors. About 6,000,000 k.w.h. per annum are generated by the power station and the normal load is about 750 k.w., necessitating the running of one 500 k.w. and one 250 k.w. back-pressure set, but this load is increased in summer to 800-900 k.w. for brief periods when the refrigerating plant is in service. In the turbine-house basement there is a 30 k.w. diesel house generating set, the primary duty of which is to provide sufficient power to maintain one boiler on the line ready to start up the turbo-generators as quickly as possible after the plant has been shut down for its annual overhaul.
From the feeder panels on the main switch board the major distribution to the brewery proper is effected by two-core and three-core cables, the former being used for 420 volt power supplies only, and three-core cables for both 420 volt power and 210 volt lighting supplies. The cables are laid underground to the various building blocks of the brewery.
There are over 500 D.C. shunt-wound motors having an installed capacity of about 5,000 k.w. capacity. For speed variation shunt regulators are fitted. All motor starters are of the push-button automatic contactor type.
The Refrigerating Plant.—In common with all breweries, the demand for cooling facilities at Park Royal is heavy, the maximum demand in summer being of the order of 5,000,000 B.T.U. per hour, occasioned principally by wort and beer cooling.
There are two sections of the refrigerating plant, one being the chilled water services at 45° F. for wort and beer cooling, and the other a brine service at 25° F. for yeast and gyle cooling. The machines are CO2 compressors of the high-speed single acting vertical totally-enclosed type. The choice of a CO2 system was made on the grounds that in the event of a leakage it would be less harmful than in an ammonia system, although it was appreciated that its higher vapour-pressure characteristic would require a considerably higher operating pressure—1,300 p.s.i.g., in fact; and also that it would be slightly less efficient from the thermo-dynamic point of view than ammonia.
The plant for the chilled water services comprises five machines, two of which are capable of eliminating 2,000,000 B.T.U. per hour each when cooling water from 65 to 45° F. with condensing water at 70° F. which is the summer temperature of the direct water. The remaining three machines are capable of eliminating 1,000,000 B.T.U. each under similar conditions. The condensers are of the submerged type, while the evaporators are of the enclosed type, both of steel casings. There is one condenser and three evaporators to each unit. The compressors are direct- coupled to variable-speed motors, those for the large machines being of 200 h.p. and the small machines 100 h.p.
The brine machines are similar to the chilled water plant excepting that there are three machines each of 250,000 B.T.U. per hour capacity, direct-coupled to 50 h.p. motors. Each machine, however, has one condenser and one evaporator. Three brine pumps are provided for the circulation of brine to various sections of the brewery.
For charging the installation with CO2 gas, a charging station has been erected outside the main engine room which enables six flasks of CO2 to be charged into the plant at the same time. The charging lines are so inter-connected throughout the plant that gas can be drawn from another machine to assist in the charging of another if necessary, so that during overhaul work it is not necessary to lose any gas as it can easily be transferred to one of the other machines.
The By-products Department.—The plant in the by-products department was designed to dry all spent grains, hops and surplus yeast for disposal as by-products such as cattle food, etc. For removing the spent grains from the mash tun, a dip of 60 in. of liquor or scald is put into the mash tun and the rakes given a few turns to mix the mass thoroughly and then the outlet is opened to a “free flow” centrifugal grains pump, which delivers the mixture to a drainage vessel in the by-products. A follow-up with about 25 barrels of scald is then pumped through to clean the mains.
For the reception of grains there are four of these vessels each large enough to take the spent grains from three mash tuns. They are circular vessels in copper bearing mild steel 20 ft. in diameter and 16 ft. deep fitted with a gun-metal slotted false bottom plate similar to the mash tuns, which allows the liquor to be drawn off and returned to the brew-house system. The drainage stand is usually about 12 hours, after which the grain is put out to screw conveyors for transference to presses and dryers, the grains at this stage having a moisture content of about 80 per cent. The grains are put out by a revolving arm inside the vessel, this arm being fitted with “pitched” blades. The revolving arm is slowly turned through a power-driven gear box, the arm at the same time being lowered slowly by an “inching” device to give the blades a cut. The pitching of the blades moves the cut of grain outward to the periphery of the vessel where it falls through a port in the side to a screw conveyor below. There are 12 grains presses on the grains side each consisting of a tapered propelling screw running in a tapered perforated drum, the liquor being squeezed out through the perforations which are 22 gauge. In these presses some 40 per cent, of the moisture is pressed out. The pressed grains are discharged to a screw conveyor for transference to a bank of five cylindrical steam-heater driers of more or less orthodox pattern, each drier being capable of producing 10 cwt. of dried grains per hour. The drying medium is exhaust back pressure steam at about 27 Ib. p.s.i.g. On average the driers operate on a ratio of 3 lb of steam to 1 Ib. of dried grains.
On the spent hops side a similar arrangement exists excepting that there are two draining mash tuns, four presses and three hop driers of similar type to the grains driers, having an output of 3 cwt. of dried hops per hour, and the steam ratio here is 4 Ib. of steam to 1 Ib. of dried hops.
The pressed yeast in the fermenting house is liquefied in tubular steam-heated heat interchangers (designed for turbulent flow), the liquefied yeast which remains in the liquid state when cold being pumped across to the by-products to a reception tank above the yeast driers. There are four yeast driers of the steam-heated drum type, the dried yeast being scraped off by a knife edge; the output of each drier is 1 cwt. per hour. Here the steam ratio is 7½ lb. of steam to 1 Ib. of dried yeast.
The by-products plant can deal with the whole of the spent grains, hops and yeast from a full brew in two shifts. On the grains and hop sides there are centrifugal fans and cyclones for collecting all dried material; bagging off plant is also provided.
Fuel Economy.—As most of those concerned with the brewing industry will concede, economy in fuel did not receive much consideration in pre-war days for the very good reason that as an item of production cost, fuel did not represent a particularly important percentage. However, times have changed, with the result that apart from national economy considerations, fuel costs in the industry are an item not to be overlooked.
The original plans for Park Royal did not include for the installation of any flow meters throughout the brewery itself, and in the power station, apart from the switchboard ammeters, the only meters installed were on one of the four boilers which was fitted up with the usual feed-water meter, CO2 recorder and coal meter, the idea being that this would be the test boiler to determine the most efficient method of operation; once this was established, it was assumed that if the other three boilers were operated in the same manner, they would be equally efficient.
From the early days of starting up to the beginning of fuel economy, there was a simple check of the weight of coal delivered to the power station against the weight of feed-water evaporated, the thermal efficiency being calculated. The calorific value of the coal was arrived at by sending a representative sample to a Research Laboratory, coal samples having been drawn from each shift during the week, these being mixed and quartered, and a representative sample made up weekly. Prior to the war years, the average thermal efficiency over the year of the boiler-house was about 80 per cent.
This system was satisfactory up to a point and gave reasonable results as far as the boiler-house was concerned, but as a basis for fuel economy as conditions in 1942 demanded, results were quite inadequate as it was not possible to know what was happening throughout the brewery. In common with most industries, fuel economy measures in 1942 were started by making a detailed survey throughout all departments using heat in any form, to decide whether flow meters and recorders could be usefully installed. An interesting point of this survey was that it brought to light the rather startling fact that the coal/beer ratio was varying between 46 and 65 Ib. of coal per barrel brewed, this consumption being for all brewery processes and services.
A technical Fuel Officer was appointed and flow meters were installed on all major users of steam and hot water, the meters being of the indicating, integrating and recording type, the majority being fitted with 1,000-hour charts. A system of weekly analysis was inaugurated, from which the consumption of all heat-using services, i.e. steam, electricity, gas, etc., could be assessed for each heat-user unit and also for each department, and any undue consumption readily indicated either for a particular item of plant or a department. To investigate any unusually high rate of heat use, the 1,000-hour indicating charts were referred to, allowing deduction to be made as to where the excessive consumption occurred and when; compared with the process programme of the day, the reasons for and why excess occurs are usually ascertained.
The installation of the meters cost about £3,500, and in the first year of use they were primarily responsible for a substantial reduction in the coal bill equivalent to a value of £8,000. Factors for converting the coal, steam, electricity and gas consumption to B.T:U.s have been calculated and these with the standard analysis sheet enable the weekly figures to be prepared by non-technical personnel.
This method of metering and analysis has reduced coal consumption from 45-65 Ib. of coal per barrel brewed for all brewing processes and services to a steady average of 30-32. As a matter of fact the basis of comparison is on B.T.U. per barrel brewed, which is a more reliable figure, as it makes allowance for the variations in the calorific value of the coal which to-day may be anything from 10,000 to 13,000 B.T.U. per Ib.
A typical week’s fuel consumption analysis is as follows:—
In conclusion, the author wishes to express his thanks to the Directors of Messrs. Arthur Guinness, Son & Co., Ltd., for permission to publish this paper.