Chapter 11

A REFINERY VACUUM PAN AND PUMP

ARRANGEMENT OF STEAM COILS IN A VACUUM PAN

There are many interesting and intricate problems in connection with the extraction of the sugar from the wash waters, sweet waters and low-grade syrups that are constantly accumulating in a sugar refinery, but space will not admit of their being dealt with here. Suffice it to say that the process of extraction is carried to a point where the sugar recovered barely pays for the labor and fuel expended in the operation. The ultimate result is white sugar, table syrup and molasses.

This molasses is used largely in the manufacture of vinegar and alcohol. Mixed with grain and alfalfa meal, it makes an excellent stock food that cattle take to readily and that possesses high value as a fattening agent. The sucrose and glucose content of molasses as it leaves the refinery is about fifty per cent.

Naturally, in a process involving so much handling, filtering and boiling, there must be some loss, and the efficiency of a refinery is based upon the percentage of granulated sugar recovered from the raw article delivered to the melt. It may be stated for general guidance that, taking an average of the refineries of the United States, one hundred pounds of refined white sugar is made from each one hundred and seven pounds of ninety-six-degree raw sugar melted. Some of the sugar lostis accounted for in the molasses, in the sediment from the filter presses, and in the wash waters from the char filters. The remainder is the undetermined loss in handling, in sugar destroyed by heating, and in sugar dust escaping during the manufacturing operation. As has been said, the component parts of raw sugars vary more or less, and the recovery in white sugar from two lots of raws, each polarizing ninety-six degrees, might differ considerably according to the refractory matter in the original raw sugar.

The following figures give a fairly accurate idea of the disposition of one hundred pounds of ninety-six-degree raw sugar in refining:

The undetermined loss includes every loss from the time the raw sugar is weighed into the warehouse until the granulated article is sold to the buyer. It is evident, therefore, that one of the principal items of refining cost is the actual loss of weight in converting raw into refined sugar. Assuming that the raw sugar costs four cents per pound, the refiner has lost on each one hundred pounds melted, four cents × 6½ pounds, or twenty-six cents, less the small value of the resulting molasses. If the raw sugar cost six cents, the loss would be thirty-nine cents. At four cents, the loss is equivalent to $5.20 per ton, or, in the case of a refinery melting two million pounds of raw sugar daily, $5,200.00 for each working day. This does not include anyof the operating expenses, such as labor, fuel, bone-char, containers, selling expense or administration—just the actual value of the raw sugar lost in the process of refining.

REFINERY CENTRIFUGAL MACHINES

EXTERIOR VIEW OF SWEATER

PURGING CRYSTALS FROM THE SYRUP

Returning to the sugar left in the centrifugals, the force developed in a machine forty inches in diameter, spinning at the rate of eleven hundred revolutions per minute, is so great that it quickly dispels all the liquor surrounding the crystals, leaving them nearly dry, in a solid, vertical wall. Water, filtered to insure its purity and cleanliness, is then sprayed on this spinning wall of sugar, only to be immediately thrown off through the sugar by the centrifugal motion. In passing through the sugar it washes the last of the syrup from the grains and leaves them perfectly white. Cold water, rather than hot, is used for this purpose, as it dissolves less sugar.

In former years a small quantity of bluing was added to the spraying water in order to enhance the whiteness of the sugar, just as bluing is employed in washing fine linen fabrics. Since the pure-food laws became effective, however, the practice has been discontinued in all cane-sugar refineries.

After the sugar is thoroughly washed, the centrifugal machine is stopped, a large valve in the bottom opened and the mechanical discharger rapidly ejects the sugar (now containing only about 1.2 per cent moisture) from the machine into a storage bin beneath.

For some reason not well understood, the next step in refining is called “granulation.” Actual granulation, or crystallization, takes place in the pans, and the process about to be described should properly be called drying. The manufacturing term, however, is as given.

Drying is effected in an apparatus consisting of two large cylindrical drums of wrought iron. These drums are about six feet in diameter, thirty feet long and have a slight downward pitch from the receiving to the discharging end. The first drum rests on the floor, directly below the storage bin, and is called the sweater. It turns slowly on revolving wheels, by means of circular tracks bolted to it. The power that moves it is delivered from an electric motor, through a pulley, shaft and pinion, the latter working in a gear bolted to the outside circumference of the drum. Fastened to the inner surface of this drum is a series of short, narrow shelves with saw-tooth edges that serve to carry the sugar to the top of the revolving cylinder, whence it falls to the lower side, causing a continual shower of sugar throughout the entire length and breadth of the drum. The sugar is delivered through a pipe at the upper end of the sweater, and the revolving motion together with the incline of the cylinder gradually works it down to the lower end. Here it drops through a chute to the granulator on the floor below, where the process of drying is completed.

A strong current of hot air is drawn through the sweater by a powerful fan connected to the upper end by a very large pipe. The air introduced in this way is brought to a high temperature by passing around a number of coils of pipe charged with steam, which are placed directly in front of the sweater. The hot air sweeping through the drum absorbs nearly all of the moisture in the sugar, which carries 1.2 per cent of water when it enters the drum and about 0.1 per cent as it leaves it.

The granulator, or lower drum, is the same size as the sweater and is constructed in very much the same manner, having shelves for carrying the sugar to the top and dropping it at the proper point, and being equipped with a large fan to draw off the hot, moist air. Instead of having steam coils in front, however, it has in its center a steam-heated drum about twenty-fourinches in diameter that revolves with it. The sugar crystals, as they fall in a shower from the shelves, come in contact with the hot inner drum on their way through the granulator, and in this manner become thoroughly dried. The moisture in the sugar, as it emerges from the granulator, is less than four-hundredths of one per cent, an amount too slight to determine except with the most delicate apparatus.

FRONT VIEW OF SWEATER—SHOWING STEAM COILS FOR HEATING THE AIR

INTERIOR VIEW OF SWEATER

To insure perfect drying, the damp sugar must be fed to the upper drum or sweater with unfailing regularity. This is accomplished by the use of revolving screws located under the storage bins. By turning a certain number of revolutions per minute, they deliver an even and steady supply of sugar.

From the granulators the sugar is dropped on thin cotton belts that, passing around highly magnetized pulleys, carry it to the dry storage bins. The sugar is cooled to normal temperature before being packed in containers, thus preventing subsequent absorption of moisture and consequent caking.

Magnetic pulleys are used to extract any particles of iron scale or rust that may drop into the sugar after the liquor leaves the char filters. Rust sometimes forms in the pans, mixers, conveyors, elevators, sweaters or granulators, and should it get into the sugar the magnetic pulleys will surely remove it.

Storage bins and storage tanks are prominent accessories of all sugar refineries, for if a breakdown should occur at any point, there must always be a supply of material on hand to keep the refining operations going while the trouble is being remedied.

SEPARATING CRYSTALS INTO VARIOUS SIZES

The now thoroughly cold, dry and free-running granulated sugar is drawn from the storage bins through galvanized metal pipes and taken to the separators by screw conveyors, which deliver it at an even, steady feed—a most essential feature. Thesugar as it comes from the pans is made up of crystals of various sizes. It also contains a number of small lumps formed in the centrifugal machines, or in some part of the process after it leaves the pans. It is necessary to separate the crystals according to size and to screen out the lumps, for the following reason:

In some parts of the country, people have been educated to use a coarse-grained sugar; in other sections, they are accustomed to sugar of a fine grain. For example, on the Pacific coast, the demand is for the fine-grained article; the consumers of the Mississippi river valley like a fairly large grain; while the Atlantic coast trade calls for a still coarser product. There is a difference, too, as to containers. In the East the preference is for the barrel package, while the Western buyer wants his sugar put up in bags.

There are many different types of separators commonly in use, but in all of them the governing principle is the same. It is the elimination of lumps and dust from the final product and the separation of the sugar crystals according to size. The separator here specifically referred to will explain the principle as well as any other type, and a glance at the accompanying illustration will give the reader a good idea of its construction. It is made up of a number of wire screens of various sizes, fixed at a sharp incline, one above the other, and all enclosed in a tight, dust-proof steel case. At the top of the case is a steel screw conveyor by which the sugar is fed evenly and steadily across the entire width of the top screen.

On the outside face of the case are a number of shafts to which hammers are attached. As the shafts revolve, the hammers tap the various screens below, lightly and at rapid intervals, thus causing them to vibrate.

SEPARATOR—CLOSED, READY FOR OPERATION

SEPARATORS, ONE OF WHICH IS OPEN—SHOWING THREE SCREENS FOR SEPARATING THE SUGAR GRAINS

The upper screen, called the scalper, is quite coarse and allows all the sugar to fall through except the lumps, whichrun down the face of the screen into a pipe that carries them to the melt, where they begin the refining process over again. These lumps, however, represent a very small proportion of the whole.

The second screen is finer than the scalper. It permits part of the sugar to pass through, but retains a certain amount which falls down on the face of the screen, whence it is led through a pipe to a special bin. Sugar of this size is known as coarse granulated.

The next screen lets the finer grains drop through, but catches the standard granulated, which in turn is drawn off to its special bin. The last screen, an extremely fine one, retains the extra fine granulated, and this in turn is delivered to its appointed bin. The sugar passing through the last screen is so fine as to be classed as “dust,” which, not being marketable, is usually remelted.

The amount of any one grade of sugar obtained from the separator may be changed, within certain limits, by the boiling in the vacuum pans. If a large proportion of fine-grained sugar is required, the sugar boilers are instructed accordingly. It is impossible, however, to boil all the grains in each strike a uniform size, or to boil any two strikes exactly alike, so the separators are necessary, especially for removing the lumps and dust. The dust is caused by the constant falling of the dry sugar crystals against each other in the driers and granulators, and by the grinding action upon the sugar crystals in the screw conveyors.

FILLING VARIOUS KINDS AND SIZES OF CONTAINERS

When putting up his goods, a sugar refiner—like every other manufacturer—must needs cater to the wishes and tastes of the consuming buyer. The modern tendency in containers is in favor of sealed air-tight and dust-proof packages. Some refinersspend great sums of money every year in advertising the merits of special sugars packed in dust-proof cartons. Their rivals generally follow suit, as competition in the marketing of sugar is probably far keener than in any other line of business.

The plain truth is that all refined granulated cane sugar offered for sale in the markets of this country today is almost identical, irrespective of the manner in which it may be packed. The poorest quality of refined sugar made has, in all likelihood, a purity not lower than 99.5 per cent, while the highest grade cannot possibly exceed 99.9 per cent, a difference of only four-tenths of one per cent, hence it is evident that all refined sugars are practically pure, the fancy package simply meaning a fancy price.

The methods of transporting and handling the sugar after it leaves the refinery may justify the additional expense, but this is subject to argument. However, it makes but little difference to the manufacturer, as the cost of the package as well as the extra handling is always included in the selling price.

A few years ago all sugar went out in barrels or bags, while today a modern refinery turns out about twenty different styles of container, and twenty-four kinds of sugar. It is obvious, therefore, that the packing room of a refinery is an interesting place, covering as it does a large area and including a great amount of special, intricate machinery for filling, weighing and sewing or sealing packages.

In the bottom of the bins into which the sugar is delivered from the separators is a series of galvanized iron pipes, through which the sugar runs to the various filling devices, the latter being usually arranged in long rows. Under the end of each pipe is an automatic weighing machine. In packing bags, a workman hangs a bag on the weighing machine and presses a lever, thus allowing the sugar to run into the bag. As soon as the exact amount required is reached, the flow is automatically cutoff. These weighing machines are so accurate that they gauge the amount to within a fraction of an ounce. The operative removes the full bag, places it on a conveyor that runs in and level with the floor and quickly adjusts an empty one on the weighing machine. These men become so expert that a single operative will fill two hundred and fifty one-hundred-pound bags per hour. The weighing machines are designed to fill and weigh four hundred and eighty one-hundred-pound bags per hour, but the operative cannot handle them at this rate.

FILLING, WEIGHING AND SEWING 100-POUND SACKS

FILLING, WEIGHING AND SEWING 25-POUND SACKS

Four sewing machines, specially designed for sewing the filled bags, are located immediately over the conveyor and in direct line with it. As the bag passes along on the conveyor, the operative at the first machine picks up the end of the inner cotton sack and passes it through his machine, stitching it securely. The bag then passes along to the third machine, where the operative takes hold of the outer burlap bag and sews it in the same manner. Each operative has a spare machine ready for instant use in case the one he is running gets out of order. Continuing its journey to the end of the conveyor, the bag is deposited on the main belt conveyor, which takes it without manual aid to the shipping floor or the storage warehouse. A sewing-machine operative will sew as many as seventeen bags per minute, but it is trying work and the men relieve each other at intervals during the day. Both the one-hundred- and the forty-eight-pound sacks are handled in this manner. Formerly the half sacks weighed fifty pounds, but since the Parcel Post law went into effect they have been changed to forty-eight pounds to permit of their shipment by mail. Those containing twenty-five, ten, five and two pounds are weighed and sewed in much the same way, by the aid of specially designed, rapid-handling machinery. The small package machines will accurately weigh and fill five-pound bags at the rate of twenty-five packages per minute, the others in proportion.

The paper boxes, or cartons as they are called, are weighed and filled by special machinery. This machinery seems to possess an intelligence almost human. One girl feeds the cartons (the tops and bottoms of which are open) into the machine at the rate of thirty-two per minute. The machine glues the bottom, weighs the sugar to within one thirty-second of an ounce, fills the carton, glues the top, seals it and passes it on to a conveyor which delivers the finished package to a table, from which it is packed into a box for shipment. Women are usually employed in putting up the lighter packages.

A short distance from the bag-weighing machines, and running parallel with them, is a line of pipes or spouts for filling barrels. On the floor under each spout is a barrel shaker. This is a heavy cast-iron plate that is lifted about one inch, first on one side, then on the other, by the action of two cams or arms attached to a revolving shaft underneath. The shaker drops back violently on the supporting frame after each lift, causing the sugar to settle compactly in the barrel as it is filled to an average weight of three hundred and fifty pounds. Naturally, the greater the amount of sugar packed in a barrel, the less the container costs per unit of output, and as the average cost of a sugar barrel in the United States is fifty cents, the container cost per one hundred pounds of sugar is 14.3 cents.

Without the shaker, not more than three hundred and thirty pounds of sugar could be put in a barrel, which would increase the cost per one hundred pounds to 15.1 cents. This difference on a single day’s output of two million pounds represents one hundred and sixty dollars, an eloquent argument in favor of the shaker.

FILLING BARRELS

METHOD OF HANDLING BARRELS

In packing barrels, the operative first lines the barrel with heavy paper to prevent the sugar from coming in contact with the rough wooden sides and to keep it from sifting out between the staves. The barrel, thus lined, is placed on the shaker,a valve on the spout opened and the shaking barrel filled to the top. The barrel is then removed and turned over to the cooper, who heads it up and rolls it on the scale for weighing.

Before an empty barrel reaches the packing room, it is weighed and the weight (generally from nineteen to twenty-five pounds) is stamped on its side. The gross weight of the filled barrel is determined by the packing-room scales. The weight of the empty barrel is deducted and the net weight of the sugar stenciled on the head. The full barrel is then sent down a chute to the waiting freight car or to the dock for steamer shipment, or to a conveyor that automatically delivers it to the storage warehouse.

In addition to the bags, barrels, half barrels, cartons and boxes, tins of various sizes are used for the different sugars. All of these are filled and weighed automatically, and taken from the packing room by conveyors. Some of the boxes are lined with paper and some with cotton cloth; some are nailed up in the ordinary way, and others are strapped with iron at each end. As a rule, the individual tins are cased with wood, but sometimes there are a number of tins in a case. Cartons contain two pounds, three pounds or five pounds of sugar. They are packed in fiber cases holding thirty twos, twenty threes or twelve fives and also in wooden cases which hold sixty twos, forty threes or twenty-four fives each. The style of package depends upon the demand of the trade catered to.

At this point a word or two about some of the specialties, such as cube, powdered and bar sugars, as well as yellow or soft sugars, may be of interest.

The sugar from which the cubes are made is of a rather fine grain, boiled in special pans from liquor that has been filtered over the char at least twice. From the centrifugals under thepan it falls into a hopper in which there is a revolving screw. Directly over the screw is a tank containing a warm, white sugar liquor, very sticky and viscous by reason of its density. A pipe leads from the bottom of this tank to a point over the screw, and the liquor, which is controlled by a valve, is allowed to drip upon the sugar. The action of the screw causes the sugar and the liquor to become thoroughly mixed and feeds the damp mass thus formed into a spout leading to the cube press, the machine in which cube sugar is made.

At the top of this machine is another hopper, into which the damp sugar drops from the spout overhead, and revolving in the last-mentioned hopper are a number of small shafts with brass pegs inserted at certain intervals along the length of the shafts, like spokes in the hub of a wheel. These pegs are like human fingers in their action and they press the sugar down into the pockets of a large revolving drum placed directly under the hopper. Each pocket is the size of a cube or half cube. Working in these pockets are plungers, which fall back as the revolving drum reaches the highest point directly under the mechanical fingers in the hopper. The fingers fill the open pockets and, as the drum turns, the plungers, at a certain point in its circumference where a heavy bronze bar is placed across its face, slowly enter the pockets and in so doing compress the sugar into cube form.

Two belts run through the machine under the cylinder, carrying galvanized iron plates about twenty-four inches wide, or the same width as the cylinder, and thirty inches long. As the line of pockets into which the sugar has been pressed reaches the lowest point on the circumference of the drum, the plungers drop down, forcing the pressed cubes out of the pockets onto the galvanized iron plates which the moving belt carries along out of the way of the next lot coming from the cylinder. Each plate, as it leaves the cube press, contains five hundred and fourcubes and one hundred and sixty-eight half cubes, and the time required to fill a plate is between six and seven seconds.

CUBE-SUGAR MACHINE

CARTON MACHINE

The belts carry the plates to a series of ovens, or driers, so placed that a large number of plates with their contents may be inserted through a door on the belt side. When the ovens are filled with plates holding the soft, moist cubes, a current of hot air is turned on at the top of the ovens, passing out at the bottom. The hot air circulating in this manner dries the cubes and carries off the moisture. Eight hours in the ovens suffice to render the cubes thoroughly dry and hard. They are then removed through doors opposite to those through which they were put in. This arrangement prevents the men who are putting the cubes into the ovens from interfering with those taking them out, for the process is a continuous one and cubes are placed in and removed from the ovens at the same time. As the cubes are taken out of the ovens, they are deposited on a belt conveyor which delivers them into bins in the packing room, ready to be put into boxes, bags, barrels and other containers.

Powdered and bar sugars are made by grinding coarse granulated sugar into fine particles and then separating these particles by screening them through fine silk cloth. The bolting of flour is a similar process. Powdered sugar has a decided tendency to cake and become hard, and the coarse sugar from which it is ground should be particularly free from moisture. After being crushed or ground between corrugated rolls turning at high speed, the ground sugar passes into a screening or sifting device, of which there are many kinds in use, the most common being the horizontal, revolving centrifugal screen. The crushed sugar goes in at the head end, and, as it enters, a number of revolving arms throw it against a silk screen on a circular frame,revolving in an opposite direction, that permits the finest, or powdered, sugar to pass through a silk cloth having over sixteen thousand openings per square inch.

The powdered sugar extracted, the remainder drops into another screen where a similar sifting action takes place, the silk of the second screen being coarser than that of the first, and bar sugar is the result. Such grains as are too large to pass through the bar screen are carried back to the rolls and reground. The bar screen has about five thousand openings per square inch.

Bar sugar, as the name implies, is generally used in preparing beverages. It dissolves almost instantly when dropped in water. Singularly enough, the average housewife is not aware of the advantages attending the use of this grade of sugar. It does not become caked as readily as powdered sugar does, and is the ideal sweetening for berries and cereals served at the breakfast meal. It is far more desirable than powdered sugar for most of the purposes for which the latter is commonly used.

It is believed by many thatallpowdered sugar is adulterated with chalk, starch, white corn meal or similar substances. Such is not the case, and it is safe to assume that no mixing whatever is done by any refiner in America. Powdered sugar has a strong tendency to cake or become hard, and some manufacturers who buy coarse granulated sugar from the refiners for grinding purposes use starch to the extent of from two to three per cent. Chalk is never used, nor are other non-edible or deleterious substances. Starch is not introduced for the purpose of making a greater profit, but to prevent the powdered sugar from caking. The adding of starch, in all probability, increases the cost of making powdered sugar, as starch costs almost as much as sugar, and the expense of handling it and feeding it into the grinding machinery is quite an item.

FILLING, WEIGHING AND SEWING 2-POUND, 5-POUND AND 10-POUND BAGS

Yellow sugars, or “softs” as they are usually called, comprise fifteen grades, ranging in color from a creamy white to a dark brown. These sugars are used chiefly by bakers in making gingerbread, pies and cakes, although a small quantity finds its way directly into households for ordinary domestic consumption.

The characteristics of yellow sugars are that they have a small grain and contain a sufficient amount of molasses to make them moist to the touch, properties brought about by a radically different method of boiling from that applied to white sugars. They also contain a certain amount of invert sugar which preserves the softness of grain and prevents subsequent caking or hardening.

To properly explain how yellow sugars are boiled, reference must be made to the method of boiling white sugars, which may be briefly summarized as follows:

The object to be attained in boiling white sugars is the separation of the crystallizable sucrose contained in a given solution from the impurities, moisture and non-crystallizable content of that solution. The formation of sugar crystals is a natural result of the evaporation of the moisture from the liquor or solution. In order to obtain pure white crystals, it is vitally essential that, as far as possible, all impurities and non-sugars, except water, be removed from the liquor before the boiling takes place, for if the coloring matter is not thoroughly taken out, obviously the crystals will be colored. The purifying and decolorizing operation is accomplished in the char filters. After the grain is once formed in definite crystals, these crystals attract and appropriate the sucrose in solution in the process of building up their structure, while repelling or excluding the impurities, so that in consequence the latter remain in solution. Irrespective, however, of whether crystallization of sucrose takesplace in solutions of high or low purity, it will only partially remove the sucrose from the solution in one operation, the limit being fixed by the amount and nature of impurities present. In order to bring about further crystallization of sucrose the solution or mother liquor surrounding the crystals must be separated from them and be again diluted, filtered and concentrated.

Briefly, the procedure in boiling white sugar in a vacuum pan is to take liquors of the highest purity for the first boiling. After the first crystals have been removed from the mother liquor in the centrifugal machines, the liquor is again diluted, decolorized by bone-char and boiled to grain. This operation is continued a number of times, the purity of the liquor decreasing each time. Finally, when the purity of the liquor falls to a certain point, the boiling is discontinued, for at this point conditions do not admit of further formation of pure sucrose crystals, and, if the process were pursued further, the resulting sugar would not be white. Therefore, when this state is reached, these low-grade liquors are boiled into a semi-refined sugar, commonly called “refinery raw,” which corresponds fairly closely in test with the original raw sugar, or they are used for making soft yellow sugars as explained later on. This refinery raw is then washed, melted and put through the whole process all over again. The liquor, from which the crystals formed in repeated boilings have been removed as made, at length becomes so charged with impurities that further crystallization of sucrose is impossible and this residue, or final waste, is known as blackstrap molasses.

This manner of boiling white sugar has been called the “out and out” method, in contradistinction to the “in and in” method employed in boiling soft yellow sugars, of which a few words of explanation now follow.

In boiling soft yellow sugars, the aim is to produce a large number of small sucrose crystals having the property of attractingand combining with the molasses content of the liquor and that will retain some of the molasses after they are purged of mother liquor in the centrifugal machines. This process gives a sugar that may be described as a mechanical mixture of sucrose, invert sugar and the non-sugars in the molasses.

In the case of yellow sugars, the lighter the color the better price they bring. The greatest profit, therefore, is derived from the manufacture of sugars of the lightest color and carrying a reduced percentage of sucrose. In boiling such sugars, low-purity liquors from which the coloring matter has been removed as far as practicable by bone-char filtration are required. For the purpose, it is generally found most advantageous to use the liquors taken from white sugar massecuite at the point when, owing to repeated boilings, its purity has fallen so low that further extraction of pure white sucrose crystals is impossible.

As a result of the numerous filtrations through bone-char preparatory to reboiling in the manufacture of white sugar, these liquors are usually lighter in color than any of corresponding purity obtained in the refining process. Nevertheless, they are not necessarily the only liquors suitable for the purpose, and this particularly applies to the making of the lower grades of yellow sugars. It is, however, beyond the scope of this book to elaborate upon that phase of sugar refining. The object sought here is to give a general idea of how yellow sugars are boiled, without going into all the details.

As is the case with white sugars, yellow sugars are made by a succession of boilings in vacuum pans, the liquor used for each boiling or strike being that obtained from the massecuite of the previous strike. The operation is continued until the liquor becomes too low in purity and dark in color. Each successive strike boiled is lower in test than the preceding one, due to the fact that the sucrose crystals represent the purest part of the massecuite, and, consequently, each time they are removedthe quality of the liquor is lowered. This accounts for the various grades of yellow sugar that are made, fifteen in all, starting with a creamy white and ending with a dark brown. The sucrose content of the best is about 92 per cent and that of the poorest about 80 per cent.

In making white sugars, the aim is to produce from liquors of high purity sucrose crystals that are pure white, hard and absolutely free from molasses.

In making yellow sugars, the object is to boil from low-purity liquors soft sucrose crystals that possess the property of attracting and retaining the molasses and to make this combination of crystals and molasses as complete as possible.

The essential difference between the two methods, as well as the appropriateness of the descriptive terms “out and out” and “in and in,” will be readily apparent.

The impurities in yellow sugars are natural and consist of invert sugar, glucose, organic non-sugars and salts, all of which were originally present in the raws or were formed in the process of refining.

It is not unusual to hear it said that yellow sugars are sweeter than granulated. To the average palate this is apparently so, but, as has been shown, granulated sugar contains 99.8 per cent of sucrose or sweetening matter, while the highest grade of yellow carries only 92 per cent. Soft sugars dissolve more readily on the tongue than granulated, and the syrup or molasses in them accentuates their sweet taste.

There are several other grades of sugar prepared for the consuming market, but lack of space precludes a description of them or the methods by which they are produced.

It is needless to say that the conveying, melting, filtering, boiling, drying, screening, weighing and packing of one thousandtons of sugar in twenty-four hours necessitates a great amount of steam and a multiplicity of machinery.

The boilers generate steam to drive huge pumps that deliver cold salt water to the condensers throughout the refinery, to drive vacuum pumps that make boiling and evaporationin vacuopossible, and to drive large turbine or reciprocating engines that supply the electric power. The exhaust steam as it leaves the cylinders has a pressure of about fifteen pounds per square inch. It is conducted through pipes to the evaporators, pans, driers and tanks, where it is again used for concentrating the liquors, boiling in the pans, drying the sugar and keeping the liquors hot throughout the process. It leaves the various heating coils and tubes as hot water and is returned to the boilers for the generation of more steam.

Live steam, that is to say, steam just as it comes from the boilers, is used extensively in the vacuum pans for boiling the liquor to grain.

A refinery melting one thousand tons of raw sugar each day requires about 5500 boiler horse power. On the Atlantic coast coal is the fuel used, while on the Pacific coast oil is burned. The amount of fuel consumed in different refineries varies to some extent, but a fair average per ton of raw sugar melted is one and one-third barrels of oil, or one-third of a ton of coal.

In modern plants all the moving machinery, except the pumps and main engines, is usually driven by electric motors. This does away with many dangerous belts, as well as expensive transmission machinery. The motor drive is simple and efficient and therefore used extensively.

The mechanical department is under the general supervision of the superintendent, but in direct charge of a mechanical-electrical engineer. This man is known as the chief engineer, and he is directly responsible, not only for the operation of all the machinery in the plant together with its upkeep and repair, buthe has also to cope with engineering problems that are constantly arising. Under his direction, a corps of draughtsmen is always busily engaged in planning and designing improvements and additions. He also maintains a force of mechanics, watching, operating and repairing the machinery. These men represent almost every trade, including machinists, blacksmiths, coppersmiths, tinsmiths, millwrights, boilermakers, riggers, masons, painters and many others.

The diversity of the mechanical work around a refinery is remarkable, and the engineer in charge must be a man of exceptional mechanical ability, as his duties include not only steam, electrical and civil engineering, but construction engineering of an advanced character. As refineries are always built on sites bordering on deep water, harbor engineering problems are also constantly before him.

In connection with every refinery there are many shops, where mechanical work incidental to repairs and construction is carried on. These shops are equipped with the necessary tools and implements for quick repairs and are under the supervision of the chief engineer. In addition, there is the cooper shop where many thousands of barrels are turned out daily, and the bag factory where twenty cotton bags and twenty burlap bags must be made for each and every ton of output packed in that manner.

The mechanical department of a modern refinery is as important as it is extensive, for failure in any one of its branches means costly delays. The machinery is run twenty-four hours each day, except Sundays, during about eleven months in the year. The plant is closed down the remaining thirty days for annual cleaning and repairs.

Intelligence and ability, tempered with good judgment, bring about theesprit de corpsthat gives the necessary results. The mechanical is almost as important as the chemical departmentand, as before stated, it is subject to the general supervision of the chemical engineer.

LABORATORY

OIL-BURNING BOILER PLANT

The chemical laboratory is really the heart of the institution, for upon it depends the success of every manufacturing operation. The superintendent of a refinery must possess a thorough knowledge of chemical engineering, for the process of sugar refining is largely chemical from beginning to end.

Competent chemical engineers, as distinguished from chemists, are rare, and yet their calling offers more promising prospects to young men than most other professions do today. It is clear to the intelligent observer that in these times of intensely keen competition, the manufacturer will, sooner or later, inevitably be driven to seek a considerable percentage of his profits in the utilization of by-products that now go to waste or bring but little return. The men to solve the manufacturing problems of the future will be chemical engineers. Broadly speaking, comparatively little has been done in this field in the United States, and its possibilities are incalculable.

In the laboratory, day and night, a corps of chemists is constantly engaged in the study of questions that arise in connection with the operation of the various departments. Polarizations for account of buyers and sellers of all raw sugars purchased, are made and checked there; hundreds of samples of liquors and syrups are tested daily for control work, as the purity of both must be known at all times and a record kept of their temperatures and densities. Samples of all the sugars entering the refining process, as well as of the finished product, are carefully analyzed, and upon these analyses are based elaborate calculations regarding yield and efficiency. The wash waters from the char filters are examined and tested frequently, the bone-char is tested every twenty-four hours as a check uponthe process of revivification in the kilns, and once a month the bone-char is completely analyzed to determine the deterioration that has taken place in it.

Tests are made of materials used in the refining process, such as lime, soda, acids and lubricating oils; of the feed water for the steam boilers; of the fresh water used throughout the plant; and of the fuel, whether coal or oil. Even the gases from the fires under the boilers are tested as they pass through the smokestack, in order to determine whether or not the firemen perform their duties properly.

Taking all this in conjunction with frequent tests and experimental work on driers, condensers, evaporators and other apparatus, it will be seen that there is plenty to keep a large staff of chemists fully occupied.

In refinery work, what is to be feared more than anything is the house becoming “sour.” Raw sugars and sugar liquors, and particularly the sweet waters, have a tendency to ferment, and fermentation, like fire, if not checked and brought under control before it gains much headway, soon pervades the entire establishment, affecting all the liquors and syrups, thus turning the sucrose or sugar into glucose, which cannot be recrystallized. In a refinery of two million pounds daily capacity, there is double this quantity of sugar in the house in the form of liquors, syrups, sweet water, massecuite and raws. If all of this four million pounds turned “sour,” the money loss, with raw sugar worth four cents a pound, would be about one hundred and sixty thousand dollars. Such a contingency, while remote, clearly demonstrates that chemical control is an absolute necessity.

In concluding that part of the story that deals with refining, some reference may be made to the refining cost and to the price at which refined sugar is sold.

The cost of refining sugar varies in different parts of the United States on account of the difference in the cost of commodities entering into the refining process, such as labor, fuel, cotton, burlap, containers, bone-char, etc. On the Pacific coast nearly all these items are higher than in New York, and consequently the cost of refining is probably greater.

In 1911 nearly all the sugar refiners of the United States appeared before the Hardwick Congressional committee at Washington and the testimony given by them before that body showed that the cost of refining ranged from 60 cents to 65 cents per 100 pounds.

On the day the Congressional committee began its investigation, raw sugar was selling in New York for 3.86 cents per pound, and the testimony regarding the cost of refining was no doubt based on this price for the raw sugar entering the refining operations.

It is therefore fair to assume that under normal conditions, with raw sugar at about 3¾ cents, the average cost of refining in the United States is 62½ cents per 100 pounds. This includes every item from the time the raw sugar is landed on the dock until the refined is loaded on the cars or boats for shipment. It includes the selling and overhead expenses, but not the transportation charges after the sugar leaves the refinery.

During the last six years (1909-14 inclusive) the actual differential in the United States between the purchase price of raw sugar and the selling price of refined has been 82½ cents per 100 pounds. The difference between this figure and the cost of refining represents the refiner’s gross profit; in other words, about 20 cents per 100 pounds, out of which he must pay for all additions and improvements to his plant. The remainder is available for returns on capital invested. This difference varies with the time of year and in different localities, but the average will probably hold good.

A refiner of cane sugar buys his raw product in the open market and must pay for all his operating and administration expenses and obtain his profit from the margin between the buying price of raw and the selling price of refined sugar. The cost of refining is not constant, as it varies with the fluctuating values of fuel, containers, labor, and particularly the cost of raw sugar. If it costs 62½ cents per 100 pounds to refine sugar with raws at 3.86 cents per pound, it will cost about 82½ cents per 100 pounds with raw sugars at 6 cents, assuming that such items as fuel, containers, labor, etc., remain constant. This is due to the greater value of the raw sugar lost in refining, to the heavier insurance premiums and higher interest charges. With high-priced raws, the margin between raws and refined must be proportionately greater to offset the increased cost of refining.

The refiner, like the consumer, would prefer to see sugar selling on a low basis, while the producer always hopes for the opposite.

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