Energy Savings Are In The Bag

Leading paper sack manufacturer, AssiDomän Sacks, operates an Atlas Copco variable speed drive compressor and two fixed speed units at its factory in Hull, England, to provide an energy efficient compressed air supply for many of its factory services.
AssiDomän Sacks’ Hull factory caters for the latest innovations in sack design and sack making technology. The process begins with large rolls of different grades of paper from its sister paper mills in Sweden and the Czech Republic. The paper, produced from wood from sustainable forests, finishes as a range of environment friendly, quality paper sacks of all types and sizes. Compressed air plays a major role throughout the production process, from printing to palletisation.

The Atlas Copco variable speed drive “VSD50” and two fixed speed “GA37” compressors provide between 142 and 283 l/s (300 and 600cfm) of air to cope with AssiDomän’s variable demand. A VSD50 has the flexibility to operate between 25 and 283 l/s (53 and 600cfm) so, whilst the two GA37’s run side by side, the VSD operates as a standby compressor, coming into force if the air demand increases above the capability of the two GA37’s. This gives massive cost savings as the two GA37’s are run at maximum demand without the need to run another compressor off load. The VSD, coming in automatically as a top-up, maintains compressed air levels at all times which is vital in AssiDomän’s type of operation. An oil/water separator is also in place to manage the condensate from the compressors, ensuring that only clean water is drained away in line with environmental legislation.

Compressed air plays a major role:
One major application is in the printing processes. Compressed air is used in the ink blending department for mixing inks, to enable AssiDomän to meet the stringent demands of their customers for the many designs and names printed on the outer layer of their sacks. A constant air pressure must be maintained as the blending must be agitated at all times to stop the inks congealing before they are pumped by air diaphragm pumps to the printing press ink applicators.

After the presses have re-rolled the printed paper, it is transferred to the tubing department for the sacks to be formed and glued. The sacks are then collated into bundles by air operated collators and pushed by pneumatic conveyors into a fully automated sewing line, the only one in Europe, producing over 300 sacks a minute. Compressed air is used in this process from start to finish, from mixing the inks to picking up the sacks in automatic feeding units before the stitching operation begins.

The last stop before dispatch is the new automatic press and wrap machine where the sacks are stacked onto pallets before they enter the press and strap section. Here compressed air is used to manipulate the pallet into the correct position to strap it before it moves into the wrapping section. The air is also used to pick up the top sheet by air operated fingers and pneumatic clamps before the stretch wrapping operation begins. This new palletisation line was introduced as part of AssiDomän’s palletisation project, one of a number of internal projects instigated for continuous process improvement. As the company now has an efficient air system, they will be installing a new effluent pumping system using air operated diaphragm pumps.

Energy savings of £12,000 per year:
AssiDomän Sacks continually strives to be the best paper sack manufacturer in the UK always aiming for improved quality and delivery service and to find ways of reducing customers’ packaging costs. “The energy saving combination of the VSD with two standard compressors was one of the reasons we chose Atlas Copco compressors,” explained Tony Coverdale, Engineering Manager at the Hull factory. “The good name of the company, their effective service back-up and the reliability of the equipment also attracted us.” Calculations were done prior to the purchase to ascertain how much electricity the Atlas Copco compressors would save. The results showed a reduction of £12,000 per annum on the electricity bill, meaning a pay back of only three years. Now, two years on, the compressors are living up to expectations.

AssiDomän manufactures many types of paper sack for packing a range of products from everyday household goods, such as sugar and animal feeds, to building products and hazardous chemicals. Sacks are designed according to the role they must play.

Versatility, the ability to respond to diverse needs in many industries and the materials’ impeccable environmental credentials, will secure the position of paper sacks as a major packaging medium well into the future. In much the same way, Atlas Copco’s broad range of Variable Speed Drive compressors offering flexibility, customer satisfaction and substantial reductions in electricity consumption, set a new standard in environment friendly compressed air systems.

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