WET News

TECHKNOW • The variable speed submersible pumps are from KSB's axial flow Amacan pump range • One variable speed sump pump of type Amarex KRT • The Amacan pump's own weight ensures self-centering seating of the O-ring seals • The Amacan pumps feature bearing temperature monitoring, thermal motor protection and leakage sensors NEED TO KNOW 1 The flood prevention scheme will protect more than 300 homes and businesses 2 The combination of tidal surges and overflow from a burn has created flooding problems 3 The pumping station's maximum flow rate has been specified to cover a 1 in 200-year flood event THE VERDICT The report proved invaluable in preventing expensive problems, at a later date, further into the project. AUGUST 2016 WET NEWS 9 KSB's technically advanced pumping equipment is well- suited for flood control and the Amacan pumps ensure flood- prone areas are reliably drained. KSB Amacan submersible pumps are typically used in land drainage applications and have a compact and slim design, but are extremely powerful. The Amacan's slim design makes the submersible pump ideal for installation into narrow discharge canisters. Ferrier Pumps carried out the mechanical installation at the Renfrew project site and found the pumps were easy to install as the Amacan pump's own weight ensures self- centering seating of the O-ring seals in the discharge canisters, a simple but effective design feature. The Amacan pumps come with bearing temperature monitoring, thermal motor protection and leakage sensor in the motor. They also have a low-vibration hydraulic system and a bellmouth optimised for vortex-free inflow making them an excellent choice for the Renfrew project. Well level Pump discharge rates have been defined as 1,253l/s (at 7.8m pumping head), 1,560l/s (at 3.3m pumping head) and 1,375 l/s (at 6.1m pumping head) under normal conditions. The maximum design flow for the station has been defined as 5,500l/s, which is based on four pumps working simultaneously and delivering 1,375l/s each. The pumps selected offer the best efficiency over the required operating points. The number and speed of operational pumps is controlled by PLC system, based on the water level in the pump well. Well level is continuously monitored by an ultrasonic sensor and pump operation is determined by optimisation of efficiency. When the River Clyde levels begin to rise and the water level reaches the lower limit of the modulating band the first KSB Amacan pump will be initiated at minimum speed. If the inflow is less than the pumped outflow at minimum speed, the level in the pumping station will fall and the pump will be stopped at the defined "cut out" level. If the inflow is greater than the minimum pump discharge rate, the level in the wet well will continue to rise ašer the Amacan pump starts. The sump water level will now be within the modulating band and the pump controller will modulate the speed of the pump in proportion to the level until the pump can stabilise the level at, or around the set-point level. If the duty Amacan pump operates at full speed and the level continues to rise, a second Amacan pump will be initiated ramping up from base speed until the inflow can be matched with a level within the modulating band. When there is a heavy rainfall, all four Amacan pumps can be called to run depending on the water levels in the main sump tank. Ferrier also installed in the main sump chamber a KSB Amarex KRT submersible sol- ids-handling centrifugal pump, specifically manufactured in abrasion resistant materials to remove stormwater as well as handling a relatively high con- centration of solids in the pump station. This variable speed pump is used for sump drain down following cessation of a storm event. KSB has also supplied the pump discharge canisters, which were digitally prototyped and tested using the latest 3D design sošware. The canisters were manufactured by Powerrun Project Management, of Keighley, and each 800mm diameter canister was supplied to site in three off individual double flanged sections with a combined weight in excess of 3,000kg and an overall assembled length of nearly 10m. Report The top section of each canister incorporates a DN800mm x 180° open ended discharge that feeds into the discharge chamber of the pump station from where the flow gravitates away from the Clyde. Ašer fabrication the canisters were coated with a fusion bonded epoxy coating. Before any manufacturing of products or site work began, a report covering the testing and development work was under- taken on a physical hydraulic model of the proposed North Renfrew Pumping Station and associated discharge chamber arrangement. The model was constructed to a scale of 1/7th full size and the purpose of the pumping station model study was to investigate and confirm the pumping station hydrau- lics, the proposed operating philosophy and the self-cleans- ing characteristics of the ini- tially proposed design. The purpose of the discharge chamber was to confirm the discharge bend geometry, optimise energy dissipation and de-aeration and to assess and improve outlet losses. Where required, suitable modifications were developed in each case to optimise each component of the overall arrangement to ensure acceptable operation could be maintained across the required flow and level range and with varying combinations and number of operative KSB pumps. This report proved invaluable in preventing expensive problems, at a later date, further into the project. The pumping station provides standard protection against tidal flooding from the River Clyde The top section of each cannister has an open ended discharge that feeds into the pump station's discharge chamber

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