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Pump success in pulp sludge application

Edited by the Engineeringtalk editorial team Aug 9, 2000

SCA Hygiene Products needed a sound reliable pump to drive paper sludge from a low suction head, flocculation tank, to the belt press, following tissue paper production

SCA Hygiene Products, formerly AM Paper, of Chesterfield, needed a sound reliable pump to drive paper sludge from a low suction head, flocculation tank, to the belt press, following tissue paper production.

The company chose the E080-MH1R bearing frame pump from the Newbury based, liquids handling specialist, Hidrostal.

This screw centrifugal pump replaced the multivane, industry standard, stock pump, previously used by the company.

Wastewater from the paper process is clarified through a DAF unit where air is bubbled through the wastewater and the resultant scum is scooped from the top of the tank.

This is gravity fed into a sludge tank, the Hidrostal pump transfers the sludge, having a 5-6% dry-solids content of ash and filler, at a flow rate of 22 litres/second, with a head of 11 metres.

This viscous and abrasive sludge contains entrained air.

The Hidrostal pump has a low net positive suction head (NPSH) characteristic and internal clearances can be maintained by use of the external adjustment feature, ensuring efficient pumping performance at all times.

The pumped sludge is dewatered in the belt press, passing through rollers, the water is returned to the flocculation tanks and the solids are sent off site for recycling.

The Hidrostal design combines the action of a positive displacement pump with a centrifugal outlet.

The net result is that sludges can be transported that are three times thicker than those pumped by competitor devices.

Although it was initially ordered on a trial basis, SCA Hygiene Products found that the pump worked well and soon confirmed the order.

Close consultation with the customer determined the need for an abrasion resistant lining and impeller; Hidrostal recommended a 3R code.

SCA Hygiene Products were very pleased with the pump's performance and went on to place an order for another pump.

This is used for similar duties pumping sludge from a new surge tank.

The surge tank has been added to the production line because the belt press needs to be in continuous use.

If there is a production stoppage, sludge stored in the surge tank can be diverted to the belt press, while repairs are effected and production continues.

"We are a continuous process industry, working 365 days per year," said Mr Les Dove, chief engineer at SCA Hygiene Products, Chesterfield Mill.

"We needed a highly reliable pump and this is what the Hidrostal pumps provide.

We are extremely pleased with their performance," he said.

Hidrostal bearing frame pumps provide rigid construction for stable power transfer and a centred configuration for flexible couplings.

It is a service friendly unit with long life seals, and has been developed for a working life of more than 50,000 working hours.

The standard motor is centred to the bearing frame via a seat.

The shaft is therefore perfectly aligned and requires no subsequent adjustment.

The unit has minimum shaft deflection and large area seal surroundings due to the practically clearance free precision bearing frame.

In this case, Hidrostal recommended the standard tandem seal arrangement, which is usual when pumping solids, such as paper sludge.

The Hidrostal bearing frame is designed for the heaviest loading which by minimising shaft deflection, decisively extends the service life of the pump - and thereby reducing the overall whole life costs of the pump significantly.