Rico and Wiseli :: PNEUMATIC MALTING.

PNEUMATIC MALTING.

The lethargy in the malting trade, and in all matters relating to malting processes, induced by two centuries of restrictive legislation, is being gradually shaken off by the malting industry under the new law. For many years nearly all improvements in malting processes originated abroad, as numberless Acts of Parliament fettered every process and the use of every implement requisite in a malt-house in this country. The entire removal of these legislative restrictions gives an opportunity for improved processes, which promises to open up a considerable field for engineering work, and to develop a very backward art by the application of scientific principles. The present time is, therefore, one of more material change than malting has ever experienced.

PNEUMATIC MALTING AT TROYES. Fig. 1.

Of the numerous improvements effected in the past few years, those made by M. Galland in France, and more recently by M. Saladin, are by far the most prominent. M. Galland originated what is known as the pneumatic system eight or nine years ago. This system is carried out at the MaxÉville brewery, near Nancy.

PNEUMATIC MALTING AT TROYES. Fig. 2.

Since that time further improvements have been made by M. Galland; but more recently great advances have been made in the system by M. Saladin. He has developed the practice of the leading principle, and in conjunction with Mr. H. Stopes, of London, has added improved kilns and various mechanical apparatus for performing the work previously done by hand. He has also devised a very ingenious machine for cooling the moist air by which the process is carried on.

FIG. 4.--ECHANGEUR AND TURNING MACHINE.

At the recent Brewery Exhibition, some of the machinery used in these new maltings was shown in action by Messrs. H. Stopes & Co., together with drawings of a malting constructed at Troyes for M. Bonnette under M. Saladin's instructions. This malting is the third constructed for the same firm, the others being at Nancy. That at Troyes we now illustrate. We will not occupy space by a general description of the pneumatic system, one great feature in which is the continuous manufacture of malt throughout the year instead of only from five to eight months of the year, as it will be gathered from the following description of the Troyes malting:

FIG. 5.--ECHANGEUR, AXIAL SECTION.

In our engravings, Figs. 1, 2, and 3, the letter A indicates the germinating cases; B, Saladin's patent turning screws; C A, air channels; D, passages; E R, main driving shafts; e, pulleys; F, metal recesses to fit turning screws; G, elevators; H, trap doors; I, air channels; J, openings to growing floor for air; K S, engines and fan room; L N, fans, supply and exhaust; T, boiler; U, chimney; f, well. The capacity of the malting is 130 qr. malt every day. This is equivalent to an English house of 520 qr. steep. The whole space occupied is the area necessary for kilns, malt and barley stores, engine and boiler house, and fans. No additional area is required for germinating floors, as ten germinating cases, A, are placed in the basement below the kilns and stores. The building is of brick, with the internal walls below the ground line resting upon cast iron columns and rolled joists. The germinating cases, A A, are of iron; the bottoms are double. One of perforated plate is placed 6 inches above the bottom. These plates admit of draining the corn if the germinating case is used as a steeping cistern also. Their chief object is, however to admit of ready circulation of the air by the means presently to be described. Large channels, A a, serve as drains for moisture and to convey the air to or from the growing corn. Between each case is a passage, D, enabling the maltster to have free access to the corn at all points.

FIG. 6.--ECHANGEUR TRANSVERSE SECTION.

With the exception of the driving shaft, E, all the machinery is in duplicate, so that the possibility is remote of any breakdown that would seriously affect the working of the house. This is necessary, as should the fans, L N, be stopped for twenty-four hours the corn germinating at a depth exceeding 30 inches would heat and impair its vitality. The boilers, T, and engines, S, are of the common type of 20 horse power nominal. The fans, L N, are the Farcot patent, illustrated a short time since in our pages. The lower floors of the kilns are provided with the Schlemmer patent mechanical turners. The turners, Fig. 4, in the germinating cases are Saladin's patent.

FIG. 7.--ECHANGEUR, SECTIONAL PLAN.

The germination of the grain is effected by means of cool moist air provided by the fan described and the cooler and moistener--Figs. 5, 6, and 7, herewith--known as an echangeur. As the germinating grain has a depth of from 30 inches to 40 inches some pressure is required, and mechanical means are necessary for efficient and economical turning. The echangeur is a very ingenious application of the well understood rapidity of evaporation of any liquid when spread out in very thin layers over large surfaces and exposed to a current of air. It consists of a cylinder, or series of cylinders, of increasing diameter, placed one within another. Each consists of finely perforated sheet iron. They are placed in a trough of water, just sufficiently immersed to insure complete wetting. When rotated at a slow speed, the surfaces of all the cylinders are kept just wetted. A volume of air is either driven or drawn through, as may be required for any particular purpose. In the model malting, as shown at Fig. 4, taken from that shown at the Brewery Exhibition, the air was driven through the echangeur and thence through the germinating barley. Here or as employed in the malting illustrated, the air in its passage comes first into contact with the moistened cylinders, and if hot and dry it becomes moist and cool, for the constant evaporation upon the cylinders has a very considerable refrigerating effect.

This was well known to the Egyptians over four thousand years ago, and the porous bottle--gergeleh--of Esnch has been made until the present day, to keep the drinking water cool and fresh. The echangeur is like a gigantic gergeleh, and by increasing the size and number of the cylinders, and causing the water in the moistening trough to circulate, any volume of air can be wetted to the saturation limit corresponding to its temperature. It will be seen that this apparatus gives the maltster complete control of the humidity and heat as well as volume of the air driven through germinating corn.

Fig. 8.

The turning apparatus is shown by Fig. 4, and consists, as will be seen, of a cylindrical frame provided with rollers which run on rails at the edge of the germinating cases. It is carried to and fro from either end of the case by compensating rope gearing which at the same time gives motion to the gearing actuating the turning screws. These screws do not quite touch the bottom of the germinating case, but are provided with a pair of small brushes, as shown in the annexed engraving, Fig. 8, which just skim it. The apparatus shown has but three of these screws, but the cases are generally made wide enough for six. The kilns are double, each possessing two floors, and worked upon the Stopes' system. The construction of the furnaces is of the ordinary French pattern. The arrangement of the house permits of great regularity in working. Every day 130 qrs. of barley is screened, sorted, cleaned, and passed into a steeping cistern. When sufficiently steeped it runs through piping into the germinating case, which, in the natural order of working, is empty. Here it forms the couch. When it is desirable to open couch a small amount of air is forced through the grain by opening the trap door connected with the main air channel. This furnishes the growing corn with oxygen, removes the carbonic acid gas, and regulates temperatures of the mass of grain. Later the Saladin turner is put in motion about every eight to twelve hours. The screws in rotating upon their axes are slowly propelled horizontally. They thus effectually turn the grain and leave it perfectly smooth. This turning prevents matting of the roots, the regulation of temperature and exposure to air being effected by means of the cold air from the echangeur. When the grain is sufficiently grown it is elevated to the kilns. For forty hours it remains upon the top floor. It is then dropped upon the bottom floor, a further charge of green corn following upon the top floor. The benefit is mutual. The bottom floor is maintained at an even temperature, being virtually plunged in an air bath; free radiation of heat is prevented; the top surface of the malt is necessarily nearly as warm as that next the wires, which in its turn is subject to lower heats than would be necessary if free radiation from the surface was allowed. The top floor is by the intervention of the layer of malt between it and the fire prevented it from coming into direct contact with heat of a dangerous and damaging degree. The same heat which is used to dry one floor, and in an ordinary kiln passes at once into the air as waste, is the best possible description of heat, namely, very slightly moistened heated air, to remove the moisture from the second layer of malt at a low temperature. It is of vital importance to retain this green malt at a low heat so long as any percentage of moisture exceeding, say, 15 per cent, is retained by the corn.

The regulation of temperature is shown by the diagrams, Figs. 9 and 10:

Fig. 9.

Fig. 10.

The distribution of the heated air in the kiln is rarely as uniform as is supposed, the temperature of the malt on drying floor being very different at different parts. In illustration of this, the following may be taken from a statement by Mr. Stopes of the results of an examination of the temperatures at different parts of a drying floor in a kiln in Norfolk: "A malting steeping 105 qr. every four days has a kiln 75 feet by 36 feet; an average drying area of under 26 feet per qr. The consequent depth of green malt when loaded is over 10 inches. The total area of air inlets is less than 27 feet super. The air outlet exceeds 117 feet, a ratio of 13 to 3. The capacity of head room equals 44,550 feet cube. The area of each tile is 144 inches, with 546 holes, giving an effective air area of some 32 inches. The ratio of non-effective metallic surface to air space is thus 9 to 2." The Casella anemometer gave no indications at several points, and fluctuating up and down draughts were observable at many others, especially at two corners and along the center. "The strongest upward draught pulsated with the gusts of wind and ranged from 30 feet to 54 feet per minute, a down draught of equal intensity occurring at intervals at the same spot, notwithstanding the fact that the air was rushing in at the inlets below the floor at the high velocity of 785 feet per minute. The temperatures of the drying malt and superimposed air consequent upon the conditions thus indicated were naturally as follows: At B, the place supposed to be hottest: Heat of malt touching tiles, 216 deg.; heat of malt 1 inch above tiles, 167 deg.; heat of malt 3 inches above tiles 154 deg.; heat of malt 4 inches above tiles, 152 deg.; heat of malt 5 inches above tiles, 142 deg.; heat of malt on surface, 112 deg. At A, the place supposed to be coldest: Heat of malt next tiles, 174 deg.; heat of malt 2 inches above tiles, 143 deg.; heat of malt 4 inches above tiles, 135 deg.; heat of malt on surface, 104 deg.; the heat of the air 3 feet above tiles, 84 deg.; the heat of the air 5 feet above tiles, 82 deg. Fig. 9 shows the temperature at twenty-six points close to the tiles, taken with twelve registered and accurate thermometers in the space of fifteen minutes." These and other similar tests have led to the conclusion that the best malt drying cannot be done on a single floor.

Fig. 10 is a similar diagram showing the temperatures on a drying floor of kiln at Poole, Dorset, altered to Stopes' system of drying. The temperature at different depths of the drying grain was as follows: Malt at surface of tiles, 142 deg.; malt at 1 inch above tiles, 142 deg.; malt at 2 inches above tiles, 142 deg.; malt at 4 inches above tiles, 141 deg.; malt on surface, 140 deg.

The advantages of the Saladin system over that hitherto working in Britain are numerous, and are thus enumerated by Messrs. Stopes & Co. who are agents for M. Saladin: The area occupied by the building does not equal one-third of that otherwise required. The actual growing-floor space is only about one-seventh, and the number of workmen is ruled necessarily by the size of the house, but on an average is reduced two-thirds; but the employment of much more power is necessary, and the power is used at more frequent intervals. The use of plant and premises is continuous, the processes of malting being equally well performed during the summer months. The further advantage of this is that brewers secure entire uniformity in age of malt. By the English system the stocks of finished malt necessarily fluctuate largely. All grain is subjected to the same conditions of surrounding air, exposure, and temperature. The volume of air supplied to the germinating corn is entirely under control, as are also its temperature and humidity. When germination is arrested and the green malt is drying, the double kilns insure control of the temperatures of the corn in the kilns. The infrequency of turning the germinating grain benefits the growth of the roots and the development of the plumule, besides saving much labor. No grains are crushed or damaged by the feet or shovels of workmen. The air supplied to the corn can be inexpensively freed from disease germs and impurities. The capital needed for malting can be reduced by the diminished cost of installation, and the reduced stocks of malt on hand. The quality of the malt made is considerably improved. The percentages of acidity are much reduced. The stability of the beer is increased, and a greater percentage of the extractive matter of the barley is obtainable by the brewer.--The Engineer.

Clyx.com