What was the cause of factory troubles in 2001?

23 August 2002

Wissington ways to avoid repeat delays

With potato harvest under

way and sugar beet lifting

due any week, our focus on

root harvesting over the

following three pages

starts here with a detailed

look by Edward Long at

what British Sugar

has done to prevent a

repeat of last years huge

harvest hold-ups and goes

on to provide some topical

advice on potato lifting.

Edited by Charles Abel.

See p69 for machinery topics

AFTER a £2m investment in new equipment, British Sugar is confident it has solved the filtration problems that dogged its flagship Wissington factory last campaign.

Trouble first emerged shortly after it opened for deliveries in October when filters became clogged and slowed processing. The daily slice had to be reduced by around 25% from 16,000t to just over 12,000t.

That soon resulted in a backlog of beet on farms, triggering emergency diversions to neighbouring factories at Bury St Edmunds, Cantley and Newark.

As soon as the protracted campaign ended in early March a start was made on the £2m upgrade programme to avoid similar troubles in future. The slow-down had added two extra weeks to the expected campaign length.

As the 2001/02 growing season had been unusual and the scale of the trouble at the factory almost unique, it was possible the filters would not clog again. But BS decided it could not take the risk and invested in the new kit.

The main replacement item is the crystal tank. The new one is twice the size and capacity of the old one to provide sufficient time for large crystals to form.

To provide the best conditions for this to happen the design has been revamped to ensure more vigorous agitation, and a new heater unit installed to boost the temperature from 85C to 95C.

"I am as confident as I can be that everything has been done to crack the problem and that we will not be facing filtration problems next campaign. We will have scientific support on stand-by for the first few weeks to ensure everything runs smoothly," says Wissington factory manager Melvyn Mallott.

Wissington factory manager Melvyn Mallot (right) and agricultural operations manager Mark Culloden oversee the installation of 1400sq m of fabric-weave filter elements (insert) in Wissingtons new Gaudrin filtration vessel.

&#8226 Wissington is the biggest beet sugar processing factory in Europe and produces more in a season than any other in the world. With an average daily slice of 16,000t, it can produce 1250t of sugar crystals in 24 hours with the equivalent of another 1250t as syrup, which is stored and refined the following spring and summer.

&#8226 The 1830 growers who supply 2m tonnes of beet/year – 25% of the UK crop – farm within a 60-mile radius from Oundle in the west to Boston in the north and eastwards to a line between Wells and Swaffham.

&#8226 The Norfolk factory is one of only six operating in the UK. The others are at Bury St Edmunds, Cantley, Newark, York and Allscott in the West Midlands.

&#8226 Filter blockages blamed on small lime and impurity particles due to record low level of non-sugars in beet and high pH of juice, caused by seasonal and soil factors.

&#8226 Wissington worst affected, and for longer.

&#8226 £2m investment to cure trouble.

&#8226 Scientific support on stand-by for first few weeks of new campaign.

ALTHOUGH a low level of impurities in last seasons beet is blamed for the sticky filters that slowed processing, BS wants growers to continue improving beet quality because it is cost-effective for both sides of the industry.

"The last thing we want is for growers to change current practice," says Wissingtons agricultural manager Mark Culloden. "We need beet of the same quality as from last seasons crop. It is up to us to handle them efficiently without causing delays and disruptions to normal delivery programmes."

The 2001 crop was drilled very late in the wet spring. Then a super non-stop growing season followed and beet with ultra-low impurity levels were lifted.

In future the combination of "juicy" low impurity varieties, widespread use of Advantage primed seed to achieve an even crop, reduced nitrogen applications and well balanced amounts of other fertilisers will minimise the risk of high impurity levels.

Those together with the modifications to the factory should avoid future trouble, British Sugar hopes.

Keep up beet quality in 2002

What was the cause of factory troubles in 2001?

CAUSE of the problem was soon identified as unusually fine particles of lime and impurities.

During the purification stage of processing, lime is added to raw juice extracted from beet. It attracts non-sugar impurities and is then precipitated and filtered off before the juice is concentrated.

"Last campaign these particles were abnormally small, they blocked filters and slowed the whole factory process," says Wissington factory manager Melvyn Mallott. "This started almost as soon as the campaign opened and despite our best efforts to solve the problem it persisted to the bitter end.

"At the time we thought it was a new problem, but after investigations we discovered some factories in mainland Europe have experienced similar, but far less severe, troubles in the past.

"It is also likely that small particles had clogged filters here in the past, but only briefly, and as the trouble seemed to have cured itself no remedial action was needed.

"Last year was not an easy one for filtration at Continental sugar factories and many had trouble, some here suffered slightly but no throughput was lost."

Further in-depth investigations by BSs scientific team and independent consultants revealed there were several causes for the ultra-small lime and impurity particles. The main one was the composition of impurities.

The season had resulted in beet with record low levels of non-sugars being harvested. The high purity was due to low levels of amino-nitrogen, but both sodium and potassium were at normal levels. This imbalance led to an increased pH, which only allowed small lime particles to form.

When it became clear early in the campaign that the filtration troubles were not going to cure themselves, Mr Mallott and his team did everything they and the scientists could think of to improve throughput.

"As a sticking plaster, short-term measure, we removed redundant but still functional filters from the closed Ipswich factory and installed them alongside the bank of our own filters.

"The aim was to boost our ability to remove unwanted impurities to offset the slow throughput. This was completed in just two weeks instead of the more normal eight months needed for a job of this size."

The extra filters helped to buy time and ease the immediate problem, but it was clear a more permanent solution was needed and the scientists identified the weak links in the chain that needed replacing. &#42

Flashback to fury… Growers hope to avoid a repeat of last years protest meetings, when instead of running at full capacity (above) British Sugars flagship factory at Wissington, Norfolk, saw huge backlogs of beet building up through the winter.

Crop prospects good

Initial sample digs in early August show prospects are good for this season`s crop. Although lack of sunshine has pegged sugar contents at 13.7% compared with the 5-year average of 14.6%, root weight is 34g heavier at 447g, so the amount of sugar per root is 65.1g or 30% more than the same time last year and well up on the 60.7g five-year average.

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