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.
[Illustration: 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.
[Illustration: 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.
[Illustration: 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:
[Illustration: 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.
[Illustration: 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.
[Illustration: 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.
[Illustration: 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:
[Illustration: Fig. 9.]
[Illustration: 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_.
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