24 August 2001

Clod and stone sensing for even cleaner beet?

Electronic sensing to identify

clods and stones could

provide the next step

forward in the battle for

cleaner beet. The first

system of its type will arrive

on a new cleaner-loader to

be unveiled this autumn.

Mike Williams reports

BEET arriving at factories from UK farms is as clean as any in Europe, says British Sugar, but with standards already high, further improvements in cleaning efficiency may be difficult to achieve.

Even so, machinery makers are seeking new ways to push the dirt tares even lower.

Britains reputation for delivering clean beet survived even last winters challenging conditions. Soggy fields everywhere and harvesters held up in some areas until flood water had receded, caused exceptional problems, but despite this dirt tares at the factories were less than two percentage points higher than usual, and there was only a small rise in the number of loads rejected.

Most of the credit for keeping the beet so clean is shared by the harvester and cleaner-loader operators, and the results are evidence of high levels of skill, says Robin Limb of the British Sugar factory at Bury St Edmunds, Suffolk.

"The figure for dirt tares has recently averaged between about 6% and 8% and this reflects a lot of credit on those who do the harvesting and operate the cleaner loaders," he says. "Keeping the dirt tares low while maintaining a high throughput is not easy, particularly when the lifting conditions are difficult, and there are obviously a lot of very skilful operators around.

"We have a very good record in this country for delivering clean beet. The Dutch are our nearest competitors in Europe. They are very close to our average and sometimes they are ahead of us, but most of their crop is grown on silty soils which tend to make cleaning easier. The French have the highest dirt tares. Their national average is about twice the UK level and in some areas the figure is well over 20%."

Much of the dirt, stone and trash are removed in the harvester, and modern machines will bring the dirt tare figure down to about 12% when the crop goes into the clamp. Using a cleaner-loader almost halves the remaining dirt tares and British Sugar surveys suggest more than 95% of the UK crop goes over a cleaner-loader.

Design improvements on cleaner-loaders include the addition of brush rollers from Jones Engineering. The brushes, available since the mid-1990s, are said to be more efficient for removing stones, leaving star rollers to take out dirt, crowns and other material. A typical balance would be two brush rollers and five with stars, but the numbers can be adjusted to suit working conditions.

Armer Machinery introduced its new HT 115 cleaner loader last year. Based on a modular design, the machine can be supplied with various levels of equipment starting with a pto drive while the top specification version, the HT125, has a picking-off table. Design improvements include increased width for more throughput and additional space under the machine allows easier dirt removal.

This years new arrivals include the Thyregod TR7 loader to be launched in October at the Beet UK demonstration in Norfolk. It is aimed at the high capacity end of the market with up to 250t/hour claimed throughput and design features including a hand-held remote control unit, a 100hp Deere engine and a spiral roller cleaning system.

Electronic pioneer

Electronic sensing aimed at improved cleaning efficiency is being pioneered by CTM Harpley Engineering, the only UK company specialising in cleaner-loaders. CTM claims to be the market leader selling about three out of every four of the 40 or so loaders sold in the UK each year.

Last year CTM became the first UK company to offer a spiral roller cleaning system, using a set of four rollers arranged longitudinally. The rollers, in contra-rotating pairs, have a spring loading system allowing them to move apart to eject stones up to about house brick size. A small batch of the spiral roller machines sold last year performed well, says sales manager, Nigel Mountain. This year his company had to build an extra batch when demand went ahead of their estimates.

The electronic sensing system, to be shown on a prototype loader at the beet event in October, was developed with the help of specialists at Cambridge University. Details are still on the secret list, but the system uses hi-tech electronics to identify differences between clods, stones and beet.

Rounded clods of soil or large stones can be hard to separate from the beet using mechanical methods only, says Mr Mountain, but adding electronics can significantly improve the separation efficiency and reduce the amount of dirt tares, while allowing a high throughput.

"We believe it is a significant breakthrough, and it puts us a long way ahead of our competitors," he says. "The UK market has been shrinking steadily, and the only opportunities we have to expand our loader business are by increasing our UK market share and by building up our export sales.

"The spiral rotor separation system has already brought new export business, and it looks as if it is going to increase our UK sales as well. I believe our electronic sensing system will do the same, and we think it is a very exciting development."

Efficient cleaning is becoming more important, says Mr Mountain, who adds that British Sugar is keen to see further reductions in dirt tares, partly for cost reasons but also because of environmental objections to moving lots of dirt around the country.

Closing some of the BS factories is also making a lot of growers more aware of the dirt tares problem. If a growers local factory closes it could add 50 miles or more to the round trip, which makes it even more expensive to transport dirt. It also makes it even more costly when a load is rejected. &#42

Above: The 900 series cleaner-loaders from CTM Harpley are available with the new spiral roller cleaning system. Right: Nigel Mountain, sales manager at CTM, says electronic sensing will improve the efficiency of cleaner loaders.

Some models in the Jones range of cleaner-loaders are availbale with brush rollers as well as star type plasti clleaning rollers.