ECS Engineering Services is to install a replacement screw pump at Wessex Water’s Avonmouth Sewage Treatment Works (STW), helping secure the capabilities of the facility for decades to come.
Avonmouth STW serves a population of about 1,000,000 people in Bristol and the surrounding towns and villages. One of its key pieces of process plant is a very large screw pump which has been in operation for around 40 years. However, it had become badly worn and effectively reached the end of its useful service life.
ECS was asked to inspect the screw pump and make some proposals for its overhaul or replacement. Jake Laughton, the ECS engineer who led the inspection says: “Much of the pump is in a serviceable condition and can be retained, however, the screw itself has reached the end of its life and needs to be replaced.”
At 21 tonnes, 20 metres long, 3.1 metres in diameter and able to pump 3,645 litres of water a second, the screw is simply enormous. ECS has arranged to have a new screw fabricated in Holland by long-standing partner company, Landustrie. Made in mild steel, a high-performance, corrosion resistant coating will give it a working life measured in decades.
“We have incorporated some important innovations,” says Jake, “including a stainless steel lower bearing, again made by Landustrie. This does not need an oil or grease feed, so is both ecologically sound and reduces the maintenance requirements – features that will pay dividends in the long run.”
The design team has evaluated the loading on the pump when it is in use and optimised all the new parts to lengthen the pump’s working life and maximise its efficiency and reliability.
Jamie Wesley, Operations Director at ECS states, “To be involved with machines of this size showcases the excellent capabilities available here at ECS, our screw pump experts have given the existing motor, gearbox and upper bearing a clean bill of health, which has helped to reduce the overall cost of the project for Wessex Water.”
Polymer vanes last 3 times as long in vacuum rotary pump
Vanes made of the bearing polymer Hitemp 150 have lasted three times as long as traditional vanes in servicing company Septic Tanks (Pty) Ltd’s vacuum rotary pump, a Broom B35.
The pump is used to create a pressure difference that sucks up the waste liquids from septic tanks.
The pumps involved in such operations should not come into contact with sewage ideally.
However, where septic tank pumping is not monitored continuously, overflow from the transport truck can make its way to the pressure vessel and on to the vacuum rotary pump.
The vanes in these pumps thus need to be cleaned.
In addition, the vanes need to be able to operate at high temperatures, since the pumps can overheat due to operation for long periods.
Armed with information about vane operating requirements, when the original laminate vanes in Septic Tanks (Pty) Ltd’s Broom B35 pump needed replacing as frequently as every 6 months, the waste-sector servicing company turned to Vesconite Bearings, the maker of various polymers, for a solution to this unique operating environment.
Vesconite Bearings technical sales consultant Phillip de Villiers recommended Hitemp 150, an engineered polymer that is wear resistant and can withstand temperatures of up to 150ºC.
This material will not delaminate as does the original-equipment-manufacturer supplied material, a thermosetting phenol formaldehyde resin that impregnates layers of cotton to produce a hard synthetic plastic, he reasoned.
The trial result has been impressive: Hitemp 150 did not delaminate unlike its competitor and it was resistant to overheating.
In addition, the new polymer vanes coped well with the frequent pump cleans that were required when waste material accidentally entered the pump.
Septic Tanks (Pty) Ltd owner Charl Neuhof is also pleased that the Hitemp 150 vanes continue to operate after a year and a half, while the phenolic alternative had to be replaced after six months.
Moreover, he is enthusiastic about the reduced maintenance costs that are associated with the product, which can be cleaned in-situ unlike the previous variety of vanes that had to be removed prior to cleaning because of their high levels of swelling when exposed to water.
Since testing of the B35 vacuum rotary pump vanes has gone well, Neuhoff plans to replace the vanes on its fleet of truck pumps as they fail.
His four trucks are used in the Johannesburg North, Pretoria, Hartebeespoort and Brits areas of South Africa, with three out on the road daily, each carrying six 6000 litre loads of waste material a day.
The five vanes that were employed in the B35 pump measured 35mm by 6mm by 330mm and had chamfered edges, but vanes for the other pump models that will be introducing the Hitemp 150 vanes will have different dimensions.
Sulzer’s innovative engineering solutions
Sulzer will focus on the future of the oil & gas industry in Brazil and presenting its range of solutions for pumping, separation and mixing technology, and services for rotating equipment at the Rio Oil & Gas Expo and Conference. Experts in these areas will be on hand at Stand L16 in Pavilion 4 to demonstrate the latest innovations in upstream, midstream and downstream, digital technologies and industry management. During the event, Sulzer will also be celebrating its 70th anniversary of operations in Brazil, where it has been supporting the growth of local businesses.
At the forefront of innovation and a market leader in separation and mixing technology, Sulzer Chemtech will present the latest developments in processing technology for gas/liquid and liquid/liquid separation. With its customizable, high-quality, durable and reliable columns, column internals, mist eliminators and separator vessels, there is a comprehensive range of products for the oil and gas sector at this year’s expo.
As a leading independent repair specialist and pump manufacturer, Sulzer’s extensive service offering will be represented by a number of displays including compressor rotor blades that feature specialist air spray coatings, which improve the equipment’s durability and performance. Sulzer will also showcase its capabilities in reverse engineering, testing and design improvements on a compressor impeller, resulting in the delivery of a precision-crafted replacement part with an extended service life. Also, members of the experienced field service teams from Sulzer will be present to discuss the turnkey support offered for the maintenance and repair of rotating equipment.
As digital technologies are set to play a key role in the future of the oil and gas industry, Sulzer has developed the BLUE BOX™ platform for predictive maintenance. This solution applies Industry 4.0 to oil pipelines and their pumps, analyzing data from day-to-day pump operations in near real-time and providing actionable insights to improve the performance and reliability of the system.
The company will also be exhibiting its capabilities in high-voltage coil manufacturing and testing. Complete sets of coils, designed to match or exceed original efficiency levels, are manufactured and tested on the shortest lead times in the industry, minimizing downtime and providing a new lease of life for generators and motors.
Thanks to holographic augmented reality technology, visitors to Sulzer’s stand will also be able to experience cutting-edge subsea pumps for offshore applications first hand.
Pump impeller delivers improved suction characteristics
The KSB Group has developed a special impeller for its Movitec multistage high-pressure pumps. This new impeller significantly improves these pumps’ suction characteristics (NPSH value).
It proves its worth particularly in applications with critical inlet conditions (e.g. boiler feed applications) as well as applications in which the pump is required to take in water from low-lying tanks or at higher temperatures. Under these conditions, a pressure drop in the intake area may cause cavitation to occur in the first pump stage. This can result in excessive wear of pump parts or motor bearings as well as a reduced service life of the pump due to damaged parts and an unbalanced hydraulic system.
The new impeller is offered as an alternative to the standard product. When developing the new impeller, KSB’s design engineers went to great lengths to ensure it can be used with a number of Movitec variants without necessitating modifications to the outer pump casing.
The new impeller features a modified inlet diameter, vanes allowing a slightly diagonal throughflow and a newly designed stage casing, all of which serve to substantially improve the pump’s NPSH curve.
The multistage centrifugal pumps from the Movitec range are designed for handling fluids such as water, coolants, condensate and mineral oils. They are ideal for a wide variety of applications ranging from industrial boiler feed installations in steam circuits, recirculation and fire-fighting systems, cooling water circuits and washing plants to pressure boosting in general process applications.
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