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Project Updates
ISOLATING GATE VALVES FOR WIGAN WASTEWATER TREATMENT WORKS
When a critical water treatment works in Wigan required an overhaul, T-T Flow was brought in to supply two large diameter gate valves to help ensure the continued efficient supply of potable water in the northwest of England.
Wigan Wastewater Treatment Works is an important facility operated by United Utilities, which is responsible for the delivery of potable water and the capture and treatment of wastewater throughout the region.
To ensure the continued efficient delivery and treatment of water, there was a requirement for two new large diameter gate valves to meet the required specification and facilitate safe, easy and reliable operation.
T-T Flow, the specialist valve division of T-T Pumps, was engaged to supply a pair of DN500 MSGV isolating wedge gate valves measuring 500mm in diameter. These are rated to withstand 16 Bar pressure and come with customised operating equipment utilising intelligent actuation.
As the valves would be installed beneath steel grating, each one was supplied with an extension spindle bringing the operating element (electric actuator) to an ergonomic position for safe and easy operation.
T-T was selected due to its ability to project manage the whole supply, offering an efficient single point of contact for the client. T-T Flow holds extensive stocks of Aquaflow metal seated wedge gate valves, which for this size feature superior weld deposit seating faces. Furthermore, T-T’s in-house fully equipped workshops permitted the fabrication of site-specific extension spindles and the mechanical and electrical functional testing of electric actuators.
www.ttpumps.com
UK’S FIRST LARGE SCALE AMMONIA HEAT PUMP USES ABB DRIVES AND MOTORS
Two ABB low voltage motors and low harmonic variable speed drives (VSDs) are driving the compressors for a new high-tech heating system set to transform the way homes, businesses and public buildings in Clydebank, Scotland, are heated.
The District Heating Network is the first and largest high temperature (80° C) water source heat pump (WSHP) system in the UK. The WSHP works by extracting water from the River Clyde to generate heat for buildings on the site of the former John Brown Shipyard, now known as Queens Quay.
The two 2.65 MW WSHPs are designed, manufactured and installed by Star Refrigeration in Glasgow and are part of the company’s Neatpump range. The renewable energy heat pump extracts heat from the river’s water by compressing the ammonia refrigerant in a high-efficiency screw compressor. ABB’s motors and drives are used to power the ammonia compressors, each rated at 836kW. Applying variable speed control makes it possible to increase screw compressor capacity by over-speeding up to 60Hz. The compression process raises the water’s temperature before releasing the heat via a heat exchanger to a district heating loop at up to 80° C. Pumping water through a network of underground pipes provides heating for several hundred homes and businesses in the area.
Most usefully, the VSDs reduce the starting current. Low harmonic VSDs were chosen to minimise harmonic interference on the mains supply. The VSDs exceed the requirements of EN 61000-3-12 and IEEE519 and offer genuine unity power factor with no compensation needed, thereby avoiding reactive power penalties. The standalone design of the VSD gives it a small footprint, minimising space requirements in the control panel.
www.abb.com
O-RINGS INCREASE PUMP LIFETIME FROM WEEKS TO ALMOST FOUR YEARS
When one of the world‘s leading chemical companies was looking for a superior perfluoroelastomer (FFKM) sealing solution, it approached sealing solutions specialist Green Tweed. The company’s goal was to increase the MTBF (mean time between failure) of its screw spindle pump from several weeks to several years. In addition, the company wanted to improve safety at all of the pump installations in its EO/PO (ethylene oxide, propylene oxide) plant.
The rotary pump was used as a reactor pump carrying EO/PO media. EO/PO is a very reactive, dangerous medium. In general, EO/PO users or manufacturers will not change o-ring specifications without thorough proof of compatibility.
The faces of the pump‘s mechanical seal had been statically sealed against the housing and the shaft by a variety of FFKM O-ring seals.
Previously installed perfluoro elastomers swelled and lacked sealing force. Since MTBF was only a few weeks, which was not acceptable for the customer, Greene Tweed had been contacted to provide a solution.
Based on Greene Tweed’s recommendation, the customer employed Chemraz 505 seals. This material is one of the few recommended for service in corrosive EO media.
Following the change to Chemraz 505, which reduces the risk of seal swell in EO/ PO service, the O-rings have increased pump lifetime from several weeks to almost four years. The pump continues to run without problems with scheduled maintenance now set for every five years, and it appears this goal will be met without a challenge.
