Pumps, valves and filters: advances in materials handling

Every process relies on pumps, valves and filters and the latest launches focus on ease of maintenance, fouling prevention and customisation. Sean Ottewell reports.

The biggest leap forward in progressing cavity (PC) pumps in 20 years. That's the dramatic claim that Mono is making for its new EZstrip pump, the latest addition to its well-known Compact C range.

EZstrip has been specifically designed to provide a quick and easy way to disassemble, de-rag and maintain a PC pump in-situ, eliminating the costly maintenance and down time that servicing can often cause (Fig.1).

Commenting on the launch of the EZstrip, Simon Lambert, Mono's general manager for Europe, said: "We surveyed our customer base in the waste water industry to find out what common problems they were facing. The overriding response was that ragging was becoming a serious problem, primarily because more and more unsuitable items are finding their way into the sewers. Current options available to engineers are limited, time consuming and in some cases unsafe. Our aim was to produce a pump that would minimise plant downtime and maintenance and with the new EZstrip pump we have more than met the challenge."

Once the company had addressed the ragging issue, it realised the potential of the product to minimise the time and cost involved in every aspect of maintaining a PC pump. On average, says the company, the EZstrip can reduce the maintenance time needed to replace a rotor, stator, coupling rod and drive train by 95 per cent. The average time to completely strip down a pump and replace the drive train elements is one full day; the Mono EZstrip reduces this to just a 30-minute job.

"Many of our customers can't believe that it is possible to de-rag and maintain a pump so quickly, so we have produced a video, which is now posted on our website. This shows just how easy the EZstrip makes de-ragging and maintenance of a PC pump - using just spanners and an Allen key," added Lambert.

The new pump can be installed into new plants or retrofitted into existing Compact C installations. No electrical disconnection is required and suction and discharge pipes remain untouched.

It offers dry run protection and all operational parameters are unaffected. The model range has a capacity of up to 165m3/h and 12 bar pressure, and is available in either iron or stainless steel. WRAS compliant elastomers are incorporated into the manufacture of this pump and a pre-assembled drive train, with two-year warranty, is also available.

Another PC pump innovation from Mono is the new Chroma range, which is designed to be directly interchangeable with the seepex BN series.

According to the company, replacing a current asset with a pump from the Chroma range means that users will never be left waiting for replacement pumps and parts from unresponsive suppliers.

As an example, one customer was faced with increased maintenance costs to a number of sewage sludge pumps and a decision was required to either repair or replace the existing pumps. Both options were expensive and alternative technology was also considered to transfer the sludge, but again this attracted high installation costs.

The Mono Chroma option was the ideal solution. For less than the cost of the internal pump parts and substantially less than purchasing a replacement pump or other pumping technology, the Chroma pump was supplied.

Complete with motor gearbox, all mounted on a baseplate that matched the previous seepex pump exactly, it was simply a case of dropping the Chroma pump into position, reconnecting the pipework and electrics and the pump was up and running, all with no additional installation costs. Since its installation, the pump has performed trouble free for almost a year now and is backed up by a standard five-year warranty.

Filter tackles clogging and fouling

Thirty years ago Alfa Laval patented its first automatic, self-cleaning filter. Over the years this technology has been further developed and refined. Recently a large-capacity model was added to the range - the ALF80-R (Fig.2)

When the supply of high-quality water for closed loop cooling is limited or as in some parts of the world very expensive, a widely accepted solution is to use water from the sea, lakes and rivers. However, solving one challenge creates another. In this case, preventing particles in low-quality cooling water from causing excessive fouling and expensive down time.

The ALF can be used in many sectors of industry, including power plants and district heating and cooling systems. It operates as an integral part of such a cooling system to remove debris that can foul and clog plate heat exchangers, tubular condensers, cooling tower spray nozzles and similar equipment. The filter provides protection for all downstream equipment, helping ensure better performance along with longer service life, increased uptime and reduced maintenance costs.

The ALF80-R is the largest member of the filter portfolio family to date. This new model is distinguished by a particularly large capacity, capable of dealing with the escalating demand for greater quantities of cooling water. Higher capacity means fewer filters are needed, resulting in reduced space requirements and less piping.

The complete product range, with connections from 100-800 mm, features a flexible design that makes it easy to fit and install. Automatic backflushing makes these filters easy to operate and helps ensure continuous operation, resulting in less down time.

The low pressure drop through the filter permits a greater pressure drop for the downstream PHE or condenser, which in turn makes it possible to use a smaller heat transfer area and therefore fewer plates. This cuts down on the overall cost of the PHE and, says the company, helps to provide customers with a more competitive solution.

In terms of how it works, water or other media is first pumped into a filter basket. After having passed through the filter basket, the media is discharged. Impurities with debris or other objects are kept inside the filter until flushing. As an option the process can be controlled through differential pressure measurement. However, a timer is always used in order to prevent the basket getting too dirty.

Flushing is conducted in two steps. At the first step, a flushing valve is opened and debris collected in the debris section, is released. At the second step (backflushing), a flow diverter valve placed in the basket closes while the flushing valve remains open. The closing of the diverter valve causes the full stream to divert.

After passing through the inlet section of the filter basket, a part of the stream backflushes the rear section of the filter basket to dislodge stuck debris. This ensures efficient cleaning of the basket, and debris is thus released through the flushing outlet. Meanwhile the majority of the stream passes through the filter outlet being cleaned as usual.

Slurry valve success

Meanwhile, Tyco Flow Control has designed and delivered a pneumatically operated cyclone distributor consisting of 18 Clarkson KGD slurry valves to a goldmine in Western Australia.

To install the Clarkson valves the customer's cyclone distributor was removed from the mine and taken to the company's Kalgoorlie workshop where the job was completed.

The valves were customised to enable them to fit into a compact area, but the modular design of Clarkson valves made this a relatively fast and reliable process.

The trial valves underwent preventative maintenance during their year and a half in operation. However the seats, once removed, were found to have significant life left in them.

KGD Mark III sleeves are designed for slurry service and their new face and seal profile allows easy installation and suitability for any pipe style without use of gaskets.

Whether closed or open the sleeve assembly provides positive sealing action protecting the metals parts from the flowing slurry.

The application at the gold mine is a testing one with the cyclone located in the grinding circuit of the processing plant where it separates larger particles of ore from smaller particles and returns them for grinding. Smaller particles move on to the next stage of the process where they are leached to extract their precious contents.

The valves' suitability for the application was initially demonstrated by a trial installation of two KGD valves that functioned correctly for more than a year and a half.