FACTS ABOUT...
Sugarbeets and Beet Sugar
This booklet is presented so that you can visualize more fully
the extent of the area's beet sugar industry and its significant
effect on the business economy of this region. The following
explanatory outline is designed, therefore, as background
material.
In March 1971, members of the Southern Minnesota Beet Growers Association were informed that the market for their sugarbeets would close as of that season--that the processing facility at Chaska, Minnesota would cease operations. The reasons given were small size, obsolescence, high cost of freighting beets, and the cost of renovating and adding pollution controls.
This decision left the dedicated farmers
with no market for their crop and with the unbroken history of
satisfactory sugarbeet production in this area.They immediately
began searching for a way to build a sugar factory to be owned by
the growers themselves. The obstacles and hurdles encountered
seemed to be insurmountable at times, but perseverance was a
strong point of the key individuals closely involved in this new
endeavor.
By October 1972, the Growers Association had formed a
cooperative, a suitable site had been selected, and a
considerable amount of preliminary groundwork had been laid in
the, pursuit of their goal--a sugar factory to serve the needs of
the approximate 300 growers involved. In the ensuing months,
construction contracts were let, financial arrangements were
sought, grower agreements were prepared and signed, and by March
28, 1973, the newly-formed cooperative was ready for a gala
ground-breaking event for a $60 million sugar processing
facility.
Construction began in earnest in May of 1973, with completion expected in time for the first harvest in the Fall of 1974. However, setbacks arose such as shortage of equipment for the factory, strikes by the construction workers,and the ever elusive finalization of the financing package.
With the arrival of Spring 1975, the outlook was better and approximately 50,000 acres of sugarbeets were planted. This fledgling co-op was continuing its pursuit of financing despite the many problems and the not-quite-completed factory was dedicated at a three-day celebration near the end of July in 1975.
American Crystal Sugar had been retained on an interim basis to manage the operation for the cooperative, and on October 14, 1975, slicing of the 768,000 tons of sugarbeets produced began, a large crop for a first-year campaign. New personnel, equipment failures, design defects and other problems contributed to significant delays during the early years of the operation.
In late 1978, new grower contracts were signed, a permanent financing arrangement was reached, a new management team was hired, and Southern Minnesota Beet Sugar Cooperative took over the operation of their factory, achieving the goal set in 1971.
The Southern Minnesota Beet Sugar Cooperative factory is built on one square mile of land 1 1/2miles east of Renville in south-central Minnesota. It is designed to process 6500 tons of sugarbeets per day and 11,250 cwt. sugar per day, although recent modifications have allowed for greater production. (One day records set in 1987 are 8873 tons sliced and 21,746 cwt. sugar produced). Sugarbeets are produced on 71,043 acres by approximately 311 shareholders in 13 counties covering an area 110 miles long and over 60 miles wide.
Surrounding the factory complex are settling ponds, water-holding lagoons, the five piling strips, as well as approximately 500 acres of tillable land, part of which is planted with alfalfa/grass and irrigated with waste water from the ponds.
The main process building is
480 feet long, 175 feet wide, with heights of 85 feet on the beet
end and 130 feet on the sugar end. Four concrete silos, 50 feet
in diameter and 130 feet high, plus a steel Weibull silo, 116
feet in diameter and 96 feet high, hold the bulk granulated
sugar, with capacity of100 million pounds. A 150-foot square
warehouse completes the dry storage with capacity of an
additional 70,000 cwt. comprised of 50-lb. and 100-lb.bags of
sugar. Four thick juice storage tanks, 100 feet in diameter, hold
almost 10 million gallons of thickened sugar juice which is
converted to granulated at the end of the slicing campaign. Power
for the entire operation is supplied by a 7500 K.W. turbine
generator.
During the slicing campaign, approximately 300 people are employed while the year-round employees number about 190. Contributing to the local economy is an annual payroll that exceeds $6 million.
The cooperative is governed by a 21-member Board
of Directors.
History of the Area's Plants
In 1898, the first beet sugar processing plant in Minnesota was erected at St. Louis Park. The operation of this plant did not prove successful, and when a fire destroyed it in 1905, the salvaged machinery was moved to California.
Other early installations included Chaska, Minnesota and Mason City, Iowa. Also, in 1926 construction was completed on a plant at East Grand Forks, Minnesota in the Red River Valley of the North. This plant was remodeled in 1975 to make it a 6800 ton/day plant. In 1948, construction of the second beet sugar processing plant in the Red River Valley was completed at Moorhead, Minnesota with daily capacity of 4600 tons. The third Valley beet processing plant went into operation in 1954 at Crookston, Minnesota located by the Red Lake River, also at 4600 tons/day slice.
In May 1963, construction of the Drayton, North Dakota plant began, the first sugar factory in the state of North Dakota and the fourth in the fertile Red River Valley. Drayton opened in September 1965, and is designed to slice almost 5200 tons of sugarbeets each 24-hour period.
Two additional North Dakota plants were constructed in 1973-74, both at 5000 ton per day capacity. Original owners of these plants are the Minn-Dak Farmers Cooperative at Wahpeton and Red River Valley Cooperative at Hillsboro. The Hillsboro factory, as well as East Grand Forks, Drayton, Crookston and Moorhead factories, are presently owned by American Crystal Sugar Cooperative.
In addition to processing pure beet sugar, sugar factories also produces by-product known as dried beet pulp. Pulp is the dried fiber residue left after most of the sugar has been extracted from the sliced beets. Dried beet pulp can be produced and shipped in many forms: plain dried, molasses dried (which contains approximately 25 percent molasses) and pelleted.
This excellent feed is not
only valued by dairy farmers as a stimulant to milk flow in the
cow, but it is also widely used in the feeding of cattle and
sheep destined for meat packing plants. In recent years,
substantial quantities of pelleted dried beet pulp have been
exported through the Gulf of Mexico to Japan and the
Duluth-Superior port to Europe to assist their development of
feeding programs and, in turn, help our country's balance of
payments.
Another important by-product is beet molasses, produced in quantities ranging from 4 percent to 5 percent of the weight of the beets and containing about 50 percent sugars. Beet molasses is used for production of yeast, chemicals and even pharmaceuticals, as well as in the production of mixed cattle feeds. It is acknowledged to be one of the best mediums for liquid cattle feed.
Minnesota and North Dakota officially became the nation's sugar bowl in 1974.
The 1988 intended acreage figures released by the U.S. Department of Agriculture show that approximately 509,500 acres are grown in Minnesota and North Dakota. The total slicing capacity of all seven plants in the above area is more than 37,500 tons of beets per day, with a production capacity of more than seven million tons of beets. Sugar extracted by the seven factories will exceed 20 million hundred-weights per year.
Minnesota's 334,000 intended acres place it in first position nationally while North Dakota's 175,500 acres place it in fourth. Based on the foregoing statistics, it is unlikely these two states will lose their lofty positions.
Economic benefits from the beet sugar industry in Minnesota-North Dakota will total in excess of $1 billion annually.
Other states growing sugarbeets include California, Colorado, Idaho, Michigan, Montana, Nebraska, Ohio, Oregon, Texas and Wyoming.
INTRODUCTION
It is all-important
in beet sugar operations for the technician to understand the
basic flow of the process, step-by-step, through the factory. The
process itself remains virtually the same from the early days at
the turn of the century, but its actual operation differs now
with the addition of newer equipment and controls and with the
higher standards for the finished product. The explanation here
traces the basic flow through the main stages, designated by
different colors, on the fold out in this pamphlet.
| BEET HANDLING Trash Removal DIFFUSION The Diffuser The Pulp PURIFICATION& FILTRATION First Carb The Dorr Thickener Sweetwater Second Carb Third Saturation EVAPORATION CRYSTALLIZATION & SEPARATION White Pan White Centrifugals The Granulator The White Side Lower Purity Syrups Hi-Raw Sugar Cycle Lo-Raw Sugar Cycle The Crystallizers The Melters Molasses THE LIME KILN Milk of Lime CO2 gas THE PULP DRYER Pulp Presses Pellet Mills STEAM & POWER Coal, Oil or Gas |
Sugarbeets are delivered to
the sugar factory in trucks. They are piled on the
ground, or dumped directly from trucks into wet hoppers.
The beets float into the factory by themselves by water
in a flume. On the way, they pass through a rock-catcher
for the removal of any rocks, mud or sand, and then
through another section for the removal of any trash,
weeds, or leaves. They then flow into a beet wheel to be
elevated into the beet washer. From the washer, they move
by pump and on across a roller-spray table for additional
washing. The beets are fed from the hopper into the slicers, where they are cut into long noodle-like pieces resembling shoestring potatoes. These are called cossettes. Emerging from the slicers, the cossettes fall onto a conveyor belt to be carried across a continuous weighing device and then discharged into a scalding tank leading to the diffuser. Here the sugar is removed from the cossettes by being dissolved in hot water. Water enters the opposite end to that of the cossettes, giving a counter- flow effect. The diffuser works continuously to extract sugar from the cossettes. The process of diffusion uses osmosis, or the passage of sugar through the porous membrane of the beet cossettes to the water. The sugar solution leaves the diffuser at the same end it enters in the form of "raw juice". When the cossettes reach the opposite end -- free of most of their sugar -- they become beet pulp and move on to the pulp dryer. Upon leaving the diffuser, the raw juice moves through the various stages of purification and filtration to remove impurities and other non-sugars. It is first heated in the raw juice heaters. It is then pumped to the first carbonation station. Here the raw juice is mixed with milk of lime and simultaneously treated with carbon dioxide gas (CO2) from the lime kiln. The CO2enters the gassing tank under control to give the juice the proper pH or alkalinity upon leaving the first carte station. Now the carbonated juice flows onto the Dorr thickener. The thickener tank acts to settle out the precipitate formed in the juice of milk of lime and carbon dioxide. This leaves a clear juice to be sent to the heaters and then on to the second carbonation station. The mud or sludge remaining on the bottom of the thickener goes to the drum filters for washing in order to recover any other sugar. After this, the mud goes to the holding pond. The filtrate and the wash water from the drum filters now become "sweetwater". It goes to the lime kiln to be mixed with burned lime. Any excess goes back to the first carte tank. In the second carte tank, the clear juice again mixes with CO2 gas at a controlled rate to obtain the proper pH or alkalinity. It then moves on to the second carte filters for the removal of precipitates formed by the CO2 gas and the lime left in the juice from first carbonation. This precipitate goes to the sludge tank and then back to the drum filters for further washing, while the clear juice from the second filters moves on to the third saturation station. In third saturation, the juice mixes with sulfur dioxide (SO2) gas. This gas inhibits some color forming reactions in the juice that would eventually appear in the finished sugar, but its main function is the final adjustment of pH for sugar end liquors. The juice then moves on to the evaporator supply tank and becomes known as "thin juice". From the supply tank, the thin juice moves through heaters and then to the evaporation station. This consists of five bodies, or effects. Inside the bodies, steam heat removes excess water from the thin juice in five successive stages. It concentrates the dry substance in the juice from a range of 13 percent to 15 percent upon entering the first body to 65 percent to 70 percent upon leaving the fifth body. In other words, while going through the evaporation station, the thin juice becomes thick juice. Thick juice is split at this point and that portion which the sugar end cannot handle is cooled, the pH adjusted and pumped to storage for re-entry following the slicing operation. The evaporator thick juice goes to the high melter station. In this flow, the thick juice is used to dilute and melt the high raw sugar. It is then sent through the filters to the standard liquor storage tank. The standard liquor moves on to the white pan to be boiled and crystallized to a high concentration of sugar called "white massecuite". This heavy mass then drops into the white mixer. From the mixer, the white massecuite drops into the white centrifugal machines. Here, the spinning action of the centrifugals separates the sugar crystals from the liquor containing sugar syrups and impurities. The crystals remaining in the centrifugal basket undergo further spinning for washing and some drying. The spun sugar then drops to a conveyor to be moved up to the granulator for further drying and cooling.The finished sugar then passes over screen sifters and moves on to the bulk sugar bins for storage or to the warehouse for packaging. This completes the "straight-line" flow of the process from sugarbeets to beet sugar -- but other "side-line" processes still remain to recover more of the sugar from the beet. The "white side" of the sugar end comprises only the first stage in the complete crystallization and separation process -- that is, the white pan and white centrifugals handle the material with the highest purity and the greatest yield. Other sugar -- along with important by-products -- still remain in the syrups and washwater spun off by the white centrifugals. These must be recrystallized in the sugar end. There is the "hi-green" syrup. It is spun off by the white centrifugals before the application of wash water on the massecuite. There is also the "hi-wash" spun off by the white machines during the actual washing period.The hi-wash usually flows to the hi-melter. Meantime, the hi-green goes to the storage tank and then to the hi-raw pan. There, much like on the white side, the syrup is boiled down to a high concentration, where crystallization is induced. It then drops into the hi-raw mixer. From there, it goes to the hi-raw centrifugals, where the spinning action again separates the crystals from the syrup and impurities. From these centrifugals, the hi-raw crystals go back to the process, instead of to final product storage. Hi-raw sugar moves to the hi-melter to be mixed with the high wash and also thick juice as a controlled brix or concentration. This hi-melter mixture flows back to the blow-up tank to be mixed with thick juice, where it re-enters the process as standard liquor on the white side. There is also the "machine syrup" spun off by the hi-raw centrifugals. It goes to the machine syrup storage tank on the pan floor and then to the low-raw pan, here again boiling to a concentration where crystallization can take place. But instead of going directly from the pan to the centrifugal machines, the lo-raw massecuite drops to the crystallizers for cooling and further crystallization over a period ranging from 20 to 40 hours. With this completed, the low-raw mass goes to the lo-raw mixer and then to the lo-raw centrifugal. Once again, the spinning action separates the crystals from the liquor. The lo-raw sugar goes to the lo-raw melter, with thin juice added there, and then on to the lo-melter storage tank for use in hi-raw pan. The lo-melter can also be sent to the hi-melter if quality allows. The crystallization and separation cycles end with the molasses spun off by the lo-raw centrifugals. This molasses will be shipped by rail tank car or trucks to consumers. The lime kiln supplies burned lime and CO2 gas for the regular factory process. Both products result from the burning of limestone with coke in controlled amounts in the kiln. For the regular factory process, the burned limerock goes to the slacker to be mixed with sweetwater. This produces milk of lime for use in first carbonation. The from the lime kiln enters the regular CO2 Gas factory process at both first and second carbonation. A direct by-product of the sugar process, dried and pelleted beet pulp, provides highly nutritious feed for livestock. The operation begins with the exhausted cossettes emerging from the upper end of the diffuser in the sugar factory. This pulp, still set, moves to the dryer house on belts or scrolls to the pulp press. The mechanical squeezing action of the presses reduces the moisture of the pulp to about 77 percent. The pressed pulp then enters the dryer drums, fired by oil or natural gas, where the furnaces reduce the moisture content from 77 percent to about 10 percent. Now in dried form, the pulp moves on conveyors to the pellet mills. Under the compaction of the pellet mills, the pulp emerges in a hardened form for easier handling. It then goes to bulk storage in the pulp warehouse. Almost all of the processing operations in the sugar factory depend upon the steam boiler house and electric generators for power. A critical factor in economical processing, the steam boilers may be fired either by coal, oil or gas. Steam furnishes the supply of heat required for many process operations, and also passes through a turbo-generator to provide electrical power to move machinery. |
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