EXTRAORDINARY MEET’ING HELD AT BREWERS HALL,
ON TUESDAY, 13th MARCH, 1900.
Mr. JOHN M. HANBURY, President, in the Chair.
An ordinary meeting was afterwards held, at which the following paper was read and discussed
Malt Grinding Machinery &c. : A Few Practical Experiences
By A. J. GROOM.
Some four yaws ago, I was honoured by our Institute by being asked to read a paper upon some subject of interest to its members, and again this session I have been similarly honoured; but I must ask you this evening, as I did on that previous occasion, not to regard my remarks in the light of a paper, but merely as an account of practical experiences of certain machinery we have instituted, and are now using in our brewery.
In my previous remarks I dwelt upon what I considered the two most important questions that are ever present in the brewer’s mind –
1st “The selection of proper materials”
2nd “The suitableness and cleanliness of the machinery and plant by and in which those materials those materials are to be manipulated,”
and my remarks to-night are chiefly in connection with the latter; for having agreed as to the great care necessary in the choice of our malt, I feel sure that we shall all equally agree to the care necessary in the preparation of that malt for the mash-tun. Much has been written and much discussion has taken place in connection with the subject of the best means of grinding malt, and only recently I was reading in an old book upon brewing that the writer of that book had made various experiments with different kinds of “rolls,” to find out which method gave the best extract. He ground some with stones and crushed other with metal rollers, and asserts that “the difference in produce was so trifling as to make it a matter of little importance which were used.” As I have already said, this is from quite an old book, and doubtless many here will at once differ with the idea of grinding with stones, when realising the great importance of clean tap samples.
But I think that there is yet a very important point to be considered before we come to the actual grinding of the malt, especially for brewers who are not also their own maltsters, which is generally the case in London breweries. And that is the condition in which the malt comes to the “grinding rolls.” It is only too true that the London brewer, when buying his malt, is compelled to buy large quantities to be delivered as required, and although the whole of the bulk delivered is fairly up to the sample upon which that malt was purchased, yet, unless special means are provided in the brewery for preparing it for grinding, much annoyance and difficulty may be occasioned by reason of unevenness (and consequent faulty grinding), and still more by the amount of dust, dirt, &c., contained in that malt. But mechanical skill and engineering science have very greatly aided the brewer in this particular, and it is quite within the reach of any brewer of the present day, at a comparatively moderate cost, to provide himself with a very effective means of obviating such difficulties and inconveniences as I have mentioned. And the brewer who takes this precaution will undoubtedly find his yields more stable and satisfactory, and also a certainly cleaner wort and naturally more finished beer. Of course, I refer to the excellent separating and screening machines which are doubtless familiar to most if not all present, and by means of which, not only can the corns of different size be separated and kept apart, but the dust, dirt, and other extraneous matter be prevented from polluting the gist when being ground. With the use of such separating and cleaning machines, the malt should be able to be ground with a standard of evenness which would be impossible if simply run from the “hopper” into the rolls, without any regard to the difference of condition or size of the barleys.
But to return to the chief object of my few remarks this evening, that is, “The experience of our own recently erected machinery.” I should like first to describe to you a most excellent machine which we have introduced and found most accurate and useful in the weighing of the malt before even being screened, thus enabling us to be quite sure of our quantities. I must confess to having been very skeptical to its accuracy, and consequent success, before we first used it, as I certainly was afraid that it was too delicate and intricate in its construction to indicate correctly when surrounded by the amount of dust, &c. which it would have to come in contact with, when from 60 to 100 qtrs. had to pass through it, as it had to do in our case. But subsequent experience showed me that my suspicions were quite without foundation. This machine is known as Baxter’s Patent Semi-automatic Weighing Machine, although from my own observations I think it might very rightly be described as quite automatic, as the act of weighing is in no way assisted by outside motive power, but is, by a very clever and ingenious adjustment of balances and weights, made to show the exact weight of one, two, or more bushels of malt or corn at any weight required as it runs through.
It will at once be seen how extremely useful such a machine is to brewers who buy their malt by ordinary measure, as all malt, having to be entered, for Excise purposes, before brewing, at the standard weight of 42 lbs. per bushel, or 336 lbs. per quarter, the wearisome task of weighing every quarter and bringing it to that standard weight is obviated. And again, its use must be apparent to any to whom the careful checking of any quantity of corn (of any description), purchased a given weight, is important, for, as I have already stated, the machine can be adjusted to any weight.
To illustrate to you its accuracy 1 will give you the following figures as taken personally by the ordinary scales and afterwards passed through this machine; but I should like to say that the weights on the scales were taken two floors below the machine and then the sacks had to be raised by an ordinary “sack table” to the “hoppers” over the machine, thus causing a risk of loss (by spilling, &c.), which would be almost impossible if they could have been weighed immediately beside the hoppers.
With these figures before us, for which I can vouch, I think we must agree that it is a most accurate machine, even when used for the most practical purposes and in the most practical manner. I have here diagrams in section of this machine, by which I think I can better describe it to those present who have not had the opportunity of seeing it. It is nothing more or less than a most sensitive balance working upon “knife-edged arms.” On the one side is the receptacle to contain the weights; on the other the vessel or ‘‘weighing hopper” to receive the malt or corn.
It is so arranged that when that vessel is filled to nearly the balance point the chief delivery from the “hopper” is closed, and only three small holes are allowed to remain open until the exact weight of malt or corn corresponding to the weight adjusted has passed into it. Directly that weight is reached it causes the lever or balance on the side of the machine to fall on to a movable rod, which is thrown immediately into “gear” with the cog-wheel regulating the outlet or delivery, causing the bottom of the “weighing hopper” to open and deliver the malt, &c., into the screens beneath on its way to the “rolls,” and at the same time indicating on the ‘‘indicator” attached to the machine (when the movable rod has been released from the cog-wheel) the actual weight of the malt or corn that has passed through.
Having thus correctly weighed the malt, it is passed directly into the screens and separators by means of adjustable slides. These slides are so arranged that an even “feed ” to the screen can be assured. The screen we have in use is the one known as Clinch‘s Patent, and it may perhaps seem unnecessary for me to describe so well known a machine; but I have little doubt that in addressing a meeting such as this, while there are many who have used such machines for years, there are probably others who have had little or no experience of them, and perhaps have not even seem them in motion. Therefore I am sure that I shall be excused if I give a short description of this part of our malt plant before going on to the actual subject of grinding, as such a description may be of interest, and perhaps use, to such members present.
This machine can be briefly described as a combination of cylindrical sieves with external and internal brushes, the sieves being of different sized mesh, which enable the separation of the corns of different size. These different sized corns are convoyed into separate receptacles, and subsequently run through two separate sets of “rolls,” so that the whole grist can be easily ground at an equal and even “pinch.” The importance of this separation will at once be apparent, as supposing the whole grist, of somewhat uneven malt, to pass through the same set of “rolls,” it is clear that either the small corm must be missed or the large ones ground too fine (perhaps reduced to powder) to allow the rolls to reach the smaller corns. Then again, the cleaning of the malt by this part of the machinery is a matter of great importance and benefit, as it undoubtedly ensures a far cleaner mash than is possible if no such mechanism is used. I shall have more to say upon this point a little later.
I am indebted to Mr. Walker, of Messrs. Clowes, Walker, and Co., for the loan of the diagram which I have here, of this machine, and by which I think it will be easier to follow its action.
After leaving the weighing machine and passing through the adjustable slides, the malt is delivered into the top screen, which works backwards and forwards with a somewhat fast motion, causing any rough matter, such as string, stones, &c., to be carried or thrown into a trough outside, where it is collected.
I have carefully weighed this refuse, and found on three different occasions, after 10 qtrs. had passed through, the following results:-
No.1, 4 ½ oz.; No.2, 5 ½ oz.; No. 3, 3 ½ oz. This, of course, is in addition to the dust, &c., collected after passing through the cylinders. The quantity may not appear to be large, but the very varied description of refuse one sometimes sees collected in this part of the machine cannot but convince one of the absolute necessity of some such means of preventing such matter passing through to the rolls.
The malt having passed through this screen, passes into the revolving cylinders, where the dust is separated and dispersed, a small portion falling into the spouts or shoots underneath, and collected in each, but the greater part being drawn through by the revolving “fan” above, and blown into a tank filled with water outside the building, and so washed away down the drain, thus preventing a thus preventing a deal of unnecessary dust blowing about this part of the brewery.
It is also in this part of the machine that the separation of the different sized malt takes place, and I have already referred to the great importance of separating the large and small corns, with which I am sure you will all agree; as, supposing we have no such machinery, and are compelled to grind the “grist” at a ”pinch” sufficiently close to crush the very small, it is obvious that we must crush the large corns to powder, when we may he well assured that there is a serious danger of finding the drainage in the mash-tun very defective, and also a great probability of the wort being far from as bright, in running off, as they should be. But by means of these cylinders the small malt can be allowed to pass into the special receptacle already mentioned and be treated in careful a manner in the grinding as the larger, the result, of course, being that there is less likelihood of loss of extract, and far less trouble in the drainage of the mash.
I have on several occasions been asked why this machine should not be used for its special purpose of cleaning directly the malt as delivered into the brewery, that in to my, before it is shot into the “hopper” commanding the ‘screws” and “belts” which convey it to our various malt bins. But I think the objection to this is obvious at once, when a large quantity of malt has to be stored, as there is no doubt in my mind whatever that a certain amount of dust in a large quantity of malt undoubtedly help to prevent it from becoming as slack as it would do if it had been passed through this machine on delivery and thon kept for some long period before being ground. Therefore I personally think that it is far preferable to use this screen and separator immediately before grinding. I should like to mention here a case of personal experience in support of this contention. For special reasons we were compelled to keep a “bin” or “loft” of malt (holding about 300 to 400 qtrs.) standing unused for nearly two years, and when we at last used it, in conjunction with some new malt, I was astonished to find the manner in which that malt ground, but it extremely dusty. Some present may be inclined to doubt the truth of my assertion when I say that this old malt ground infinitely better than malt that I have often soon ground after only being stored a month or two. But I am convinced that had that malt been thoroughly screened of all its dust when first delivered, it would have been absolutely necessary to have had the whole re-dried before it could possibly have been ground.
I now come to the question of the actual grinding. As I said at the commencement of these remarks, there has always been, and, I suppose, always will be, a very great difference of opinion as to which system of rolls is the best for the purpose, and I think it entirely rests with the individual brewer to find out by experience which system he prefers; and which best suits his purpose. In our own case, we always used plain rolls until we erected the present malt-grinding plant; when we substituted the “fluted” rolls. Now I have nothing whatever to say against the ordinary plain rolls, and, indeed, must confess that I very much question in my own mind if they are to be improved upon where the grist is entirely malt, but I am equally convinced; after very careful and perfectly unprejudiced experiment and experience in the working of both system, that where raw grain is used there is a distinct advantage in the drainage in the mash-tun, when the grist has been ground with “fluted” rolls, and it was only after several careful comparisons with grists ground by both methods that I came to this conclusion. I have here two samples of ground malt, one by the plain rolls, and the other by the “fluted.” The difference in the appearance of the two samples is very marked. In the case of the plain rolls, the malt is simply crushed, but in the case of the “fluted” rolls it is cut, and this latter mode of grinding appears to me to be far more satisfactory as regards drainage in the mash-tun, when a fair percentage of mw grain (maize, rice, &c.) is used in the composition of the “grist” than when the malt has been ground by simply plain-faced rolls. I should like to mention one peculiar circumstance which I have noticed in connection with the drainage of the “goods” when ground by these “fluted” rolls, which is not usual when the malt has been ground by our old system. It is the cracking of the surface, after sparging, and when the wort has nearly run off. At first I was considerably alarmed, fearing the crack extended down to the false bottom of the tun, which would, of course, have caused “channeling” and consequent loss of extract, but on examination I found it only extended a couple of inches from the surface. Again, I have observed a very great advantage in the fluted rolls in grinding. malt that has become somewhat “slack,” as I have found such malt when passed through the ordinary plain rolls showing some few corns only pressed or flattened, and not broken, whereas with the “fluted” I have never seen any that have not boon cut as they pass through, although, perhaps, in the case of the smaller corns, hardly so thoroughly or evenly as the larger.
There is another mode of grinding of which I have only heard since I commenced to write this description of our own plant. It is a combination of rolls which certainly I have never seen in practice, but I believe it is in operation in one of the Midland breweries, although, of course, it may also be in use in other breweries, although I never heard of it until a few weeks since when talking the matter over with a gentleman connected with the trade – and especially interested in this part of the brewing industry. From his description, it appears that great attention had been given by the brewers at the brewery in question to the best system of grinding, and their original rolls, which were the ordinary plain-faced rolls, were replaced by a set of fluted rolls; but although they found an advantage in the alteration, they were not entirely satisfied, and after careful investigation, came to the conclusion that something of a medium course was desirable. Therefore they adopted that medium course by having one of the rolls “plain-faced” and the other “fluted,” and I am told that this appears to have met with their entire approval, and that with this combination they still continue to prepare all their grists. As I have stated, I have never seen this combination at work, and consequently am quite unable to say anything either for or against it, and my chief object in mentioning it is the knowledge that there may be some gentleman present who have either used it themselves or have greater experience of its success or non-success than I have, and would kindly give us the benefit of their opinions upon the subject. Personally, I am inclined to think that there may be some advantage in such a combination, as it may possible minimize the chance of crushing too fine, as is likely with plain rolls, or cutting the malt too small where both the rolls are “fluted;” and I look forward with interest to the opportunity of seeing a grist that has been treated in the way mentioned and to learn more of its advantages or otherwise, and wish it had been possible to have procured a sample of such grist to have compared with the two I have here. These last remarks apply also to yet another combination of rolls of which I have recently heard. It was tried in a London brewery – but only experimentally – being the invention of one of the partners who was also a practical brewer. The idea that prompted him to try this combination seems to confirm my suggestion, that it is possible to crush too fine where only plain rolls are used, for he made one plain roll, and the other he had cased with a thick layer of hardened emery, and he tells me that the malt of the grinding of the malt was quite satisfactory, as every corn was just broken and there was an evenness in the sample after grinding far exceeding that ground by the ordinary rolls. The theory of this combination is that while there is excessive pressure with two hard surfaces, as in the case of plain steel rolls, the roll with the emery casing allows a gentle “grip” with an amount of elasticity which prevents that extreme pressure. I will now conclude these remarks by referring to the most practical quotation of all, and a quotation that I am sure anyone here would be most likely to ask, that is –Which of these systems gives the greatest extract? I will at once candidly say that I am not in a position to assert that we have found any great benefit as regards additional yield by the use of the fluted rolls, although we have found a little improvement in this respect and certainly a more constant and even yield; but I repeat that there has been unquestionably an improvement in the drainage of the “goods” and in the cleanness of the worts since the introduction of the new system when using raw grain in the mash.
With regard to the combination of the plain and fluted rolls, of course, as I have already stated, I cannot give any experience one way or the other; but it may be that at the brewery or breweries where such rolls have been employed, additional extract may have been obtained as I heard they gave great satisfaction in every way.
I think there may remain one thing more for me to do, and that is to thank you for kindly listening to these few remarks, and to repeat the hope, which I expressed on the last occasion that my temerity in standing before you tonight with those few practical details will induce other brewing members to come forward with some other practical subjects which (while not for a moment wishing to detract from the most valuable help of the essentially scientific papers we have at these meetings) would, I am sure, be most welcome to all our members who are practical brewers.
DISCUSSION
Mr. JOSEPH W. LOVIBOND said he had listened with a great deal of interest to the very practical paper which had been read, and he did not think it was possible to emphasise too strongly the necessity of the cleaning apparatus which had been described. But upon the question of the rolls, he thought there was room for some discussion. If the malt was thoroughly made it mattered very little how it was crushed, so long as the grains were properly broken for free drainage, and there was an alternative to the necessity of providing a small pair of rolls for the smaller corns. But a very different state of things arose when they had to deal, as they had in certain seasons, with hard ends and immature barley, such as would not admit of perfect malting, and which could not be properly crushed by a single pair of rolls – fluted or plain. When that was the case he found a series of rolls to be better than any division of the size of the corns. It must, he though, be forty years ago that he designed a mill, a duplicate of which is now at work, and which had three pairs of rolls, one over the other. He got at that by a series of practical experiments with wooden rolls, and with rolls of lead and soft iron, but they were all found to wear too fast. When they found they lighten the stroke of the rolls to a succession of blows, and by keeping the top rolls apart, so to strike the grains gently at first, they broke the husk and permitted the next two pair of rolls to carry out the crushing with tolerable effect. Of course, if they were content to put up with the loss of hard ends, all that would be unnecessary, but at such times as he spoke of, the corn was immature, and they could hardly afford to do that. They then had the hard ends in the position of raw grain and it was important that it should be crushed up without smashing the husk too much to prevent drainage. He had never heard ofanyone using these triple rolls for malt, but unfortunately for himself, he had not then realized that this method embodied the principle of the present system used for flour.
Mr. BEAMAN said, with reference to the double rolls, a friend of his had them placed one above the other, but he, himself thought that the better plan was to have them side by side. His friends argument was the top rolls caught and crushed the larger corn. The lower rolls, being closer, crushed the smaller corns, and did not break up the corns already crushed, but simply squeezed them together more without breaking the husk. In this way the crushing was effected without having the rolls side by side, and without the necessity of separating the large and small corns.
Mr. F. BIRD asked what was the object in having the weighing machine over the screen, instead of under. There was all this elaborate weighing for the sake of Excise, but afterward the small dust of the malt was taken out, and that must involve a loss, as though Mr. Groom put 168 lbs. of malt and dust into the hopper he could not get 168 lbs. of malt through the rolls.
Mr. GROOM explained that for Excise purposes the dust was deducted.
Mr. BIRD said that he understood that one of the objects of the machine was to enable the operator to know exactly what amount he was working up.
Mr. GROOM said so it was, but in his own case the amount of dust was deducted from the grist.
Mr. LUSH asked how long the rolls lasted and whether they required refluting very often?
Mr. GROOM replied that in his own case the rolls had been at work nearly two years. He used the old system once a week to keep them from rust, when the “fluted” rolls were looked over and cleaned, but apart from that, nothing had been done to them.
On the motion of the PRESIDENT, seconded by Mr. LIGHT, a cordial vote of thanks was accorded to Mr. Groom for his interesting lecture.
Mr. GROOM in acknowledging the compliment said he hoped other practical brewers would follow his example, and read papers on other practical subjects. The other thing he would like to mention was that the machine was being used in Austria under the Government, and there the indicator was made to show not only the weight but also the exact amount of duty paid. This was effected by a revolving dial, which showed the amount of duty payable in proportion to the amount of malt that had passed through. But that was, of course, only a question of altering the dial, the action of the machine being otherwise the same.
Crescent City Brew Talk 