“A performance test is normally a standard test of each pump, and we have a contract with the client for the guaranteed points,” Hennig said. “We give the client information about how the pump will run at these conditions. These tests show whether the specified tolerances can be fulfilled.”
The client was present to witness all the testing in every stage of the process.
Each of the four pumps could run differently. “We run it until we get it right,” Hennig said. “Sometimes, the pumps have to be adjusted or reworked to meet the client’s requirements.”
This test field includes a complete closed-loop system. Water travels through large tubes to reach the pump instead of other test fields that use open basins.
This Q-Loop Test Field runs approximately 100 tests per year and can test pumps with a capacity of up to 5,043 l/s with a maximum head of 600 meters.
Andrea Gros is an industrial engineer and is KSB’s head of production for large pumps. She was responsible for coordinating the schedule for the performance testing, a process that took a year and a team of five engineers to accomplish. Gros coordinated all the experts, designed the setup for testing, scheduled the six-week testing process, verified all the technical specifications and was the primary problem solver.
The most challenging aspects, she said, were the weight of the pump, the size of the pump, the electrical power needed and the vertical installation for a wastewater application. Every tool and accessory for the tests had to be specially designed.
Gros created a detailed schedule, which included a setup simulation to determine how long assembly and disassembly of the pump and test rig would take. The pumps were delivered in parts, and the setup had stages. The pump was assembled on the test field, and then the test rig support frame (tower) was built around the pump. After this, the impeller was installed. Then the bearing bracket was added, followed by the remainder of the tower and the motor.
“Engineers from KSB spent time at the GIW facility during the manufacturing of the pumps to understand exactly how the pump needed to be assembled and to identify how long it would take,” Gros explained.
Building the test rig for each pump requires five people working 16 hours per day for three days. “The environmental conditions of the test field were the most challenging,” Gros said. “The floor stands on springs. This is a special foundation to absorb any vibrations that could affect the other equipment. Also, calculations were made with the help of the University of Applied Sciences Merseburg, which helped determine how the testing would affect the piping system and other systems. It took two weeks to work that out. It was a flowing process. We had to just solve one problem at a time and then begin discussing the next one.”
Pumping Station Special Features
The pump station is divided into two parts and is prepared for three pumps on each side (see Image 5). In addition to the four Super Pumps and two drainage pumps, KSB also designed, fabricated and will install several ancillary features, according to Uwe Hilpmann, KSB’s project manager for the Lee Tunnel project.
KSB designed suction bends on movable devices, which glide about 9.7 meters and serve two purposes:
- They provide a connection from the suction bend to the tunnel and are used for access to the tunnel to investigate issues and fix problems.
- They provide access under the impeller.
A system, which was specially designed for this project by KSB, lubricates the bearings from a reservoir, Hilpmann said. The oil is sprayed directly onto the bearings inside the closed loop.
The Super Pumps are installed on the concrete level on a plinth (28.78 meters) and the motor is installed on the motor floor level above the pumps (35 meters). Two KSB Sewatec K 250-900 drainage pumps will be installed, one on each side of the pumping station. “If the Lee Tunnel is full of water, the water level would be about 85 meters,” Hilpmann explained. “Operating the main pumps lowers the water level by 33 meters, then they stop and the drain-down pumps take over.”
The actual flow rate of the drain-down pumps is 160 l/s (minimum) to 260,000 l/s (maximum) with actual developed head of 86.60 meters to 83.80 meters. The pump efficiency is 59.23 to 71.28 percent with 229.65 kilowatts to 299.93 kilowatts pump power absorbed. These pumps operate at 817 to 827 rpm.
Ready for Heavy Duty
Three of the world’s leading civil engineering contractors—Morgan Sindall, VINCI Construction Grands Projets and Bachy Soletanche (MVB)—are working with Thames Water to build the Lee Tunnel.
Construction began in 2010 and tunneling began in January 2011. Operation of the Lee Tunnel is expected to begin in 2016. The current target completion date for the entire Thames Tideway Scheme is 2023.