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Process benefits drive interest in peristaltic pumping

21st February 2013


Without valves, seals, or glands, peristaltic pumps are becoming the accepted low-maintenance solution for difficult pumping challenges in the process industries.

When conventional piston pumps were threatening quality at one of the most productive breweries in Europe, the solution arrived in the form of an SPX25 direct-coupled peristaltic hose pump supplied by Watson-Marlow Pumps Group.

The site in question is Anheuser-Busch InBev's Magor brewery in Monmouthshire, South Wales.

Kieselguhr, a sedimentary rock/mineral, is used by brewers as part of the critical beer filtration process. Here, a pump is deployed to dose kieselguhr in slurry form into the filter so it forms a 'bed' on a plate and frame filter. However, the unreliability of the piston pumps being used can lead to significant opportunity to introduce dissolved oxygen (DO) into the beer.

"Even the slightest traces of DO in beer can change its flavour, making it taste stale," explains Paul Evans, tech services first line manager at the Magor brewery. "This can be catastrophic for both our reputation and sales."

"It is critical for us to monitor the ingress of DO into our beers - we strive to achieve levels of less than 10 ppb (parts per billion), which is incredibly difficult over the entire brewing process where the potential for exposure to oxygen is high," says Evans. Unfortunately the stainless steel non-return valves on the discharge side of our piston pumps began to stick due to the corrosive nature of the kieselghur slurry. As a result we would end up maintaining or replacing the pumps, which would inevitably expose the beer to the atmosphere."

With three filter mains on site at the Magor brewery, InBev decided to trial an SPX25 peristaltic pump supplied by Watson-Marlow Pumps Group.

"The peristaltic operating principle intrigued us because it seemed there would be no way to introduce oxygen into our process," says Evans. "However, the proof is in the pudding so we introduced an SPX25 model to one of our filter mains."

At the Magor brewery, extensive trials were completed with flying colours, an outcome that led to the acquisition of the pump, along with two further models for the other filter mains (Fig. 1).

The SPX25, which features a rugged hub with twin-bearing rotor at its core, combines the advantages of bare-shaft construction with those of a close-coupled pump. The pump bearings absorb the forces occurring in the pump centrally, placing no load on the gearbox bearings, which means no coupling, no alignment and no heavy-duty base plate - resulting in less installation time, less maintenance and lower costs.

Food manufacturer, Greencore Group has also achieved significant savings in downtime and repair costs on the water treatment plant at its Greencore Grocery site in Selby, North Yorkshire, England, thanks to the installation of a Bredel SPX50 high pressure peristaltic hose pump from Watson-Marlow Pumps Group.

Greencore Grocery, one of the UK's leading manufacturers of bottle/jar-packaged recipe products, producing a wide range of both branded and customer own-brand sauces, pickles, and soft drinks.

The cleaning and change over process between different products, produces a small quantity of liquid waste (food effluent). This can lead to significant fluctuations in pH levels, from 4 up to 12 in some instances. Until recently, pH levels at Selby were corrected using 32 per cent caustic soda (sodium hydroxide - NaOH) through the facility's water treatment plant, which is owned and operated by United Utilities, the UK's largest listed water company. With Greencore responsible for consumable costs, a cost-down exercise was commenced to seek an alternative to NaOH.

"The Greencore Grocery facility at Selby is a high volume plant where there can be between 10 and 26 'washouts' a day depending on order schedules," says Peter Wadsworth, craft technician at United Utilities. "In order to find a more cost effective method of correcting the pH in the processing machinery, we trialled a product called Mag Mex 1060 which is a magnesium hydroxide solution (Mg(OH)2), to correct the pH levels.

Carrier water is used to dose the Mag Mex into the system at Greencore Grocery, but to do this effectively a suitable pump is required.

"To be honest we started off using fairly cheap and cheerful dosing pumps, but this proved to be inefficient as we spent two days a week repairing them," says Wadsworth. "Because magnesium hydroxide has low solubility in water it makes for a pretty abrasive fluid. We found the grit would attack the mechanical seals and drain plugs on the dosing pumps, thus requiring repair."

It so happened that one of United Utilities sister sites was using a peristaltic pump from Watson-Marlow, and this was subsequently recommended to the process engineering team at Selby. As a result, a Bredel SPX50 high pressure peristaltic hose pump (50mm diameter) was installed and ever since there have been no abrasion issues causing downtime or repair (Fig. 2).

Verder Pumps South Africa (VPSA) says that the use of its VF125 pump range has contributed to cost savings and increased productivity at platinum mines.

This was seen at a precious-metal producer's concentrator upgrade project, near Rustenburg, where VPSA was required to upgrade the thickener transfer pumps for higher production capacity, says VPSA consultant Daan Louw.

The upgrade was possible as the pumps are able to pump slurry with 1.7 specific gravity and at a flow rate of 60 m3/h over a distance of 690 m, with a height of 30 m.

This was the most difficult application for a peristaltic pump that VPSA ever had to deal with, he says.

The VF125 thickener pumps resulted in cost savings and increased production capacity, explains Louw.

Process engineering company DRA was appointed project engineer on the project and approached VPSA to assist in the design of six thickener transfer pumps.

"No other pump on the market is able to transfer the slurry without a second pump station, which would come at a significant cost to the mine and would probably take more time to process," says DRA project engineer Thys de Beer.

There are currently 24 VF125 pumps operating at 37kWh at the platinum processing plant.

The design for these pumps included installing pulsation dampeners to help decrease the pressure build-up in the pipeline, says Louw.

The build-up in the hoses is eliminated by using rubber Verderflex hoses that are designed to increase life expectancy and production performance. The Verderflex hose pumps are designed to handle tough operating conditions; they reduce downtime, decrease maintenance costs and provide easy operation and reliable solutions in difficult pumping environments.

Finally, a full range of peristaltic pump heads, pump tubing, drives, and pump systems is on show in the new Masterflex pumps and tubing catalogue. This 48-page book displays a variety of fluid handling technologies and supplies - many that are guaranteed in stock and ready to ship.

Product highlights include the full suite of durable, easy-to-use Masterflex pumps. Masterflex C/L pumps combine low flow with a compact size that is ideal for benchtop or rack mount use. The versatile Masterflex L/S pumps offer high accuracy for precise flow control and dispensing - optimal for laboratory, process or field use. Masterflex I/P pumps operate with a more powerful motor and provide better protection from hazards such as dust and water. Masterflex B/T pumps handle viscous and shear-sensitive fluids at flow rates up to 37 litres/minute - the highest flows within the Masterflex line.

In addition to pumps, tubing, and accessories, the catalogue also includes valuable references such as links to online technical resources, including a technical library, a pump system configurator tool, a searchable tubing chemical compatibility database, and an applications solutions database. See www.coleparmer.com/8029 for more

 







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