Company requirements, including the fact that the machine had to be designed to allow it to be assembled round the main drive shaft.

To guide the milling machine, which rotates around the main drive shaft, a special split-bearing sleeve on the shaft was designed. This was set concentric to the top cover outside diameter using a clocking arm.

The flatness of the top cover horizontal bearing was maintained by the machine's novel self-levelling technology, which controls the milling cutter height via an electro-hydraulic interface from the pre-set datum ring. A special split datum ring was manufactured for the purpose, to go around the drive shaft and mount on the top coven The datum ring flatnesS ~ was set using Furmanite's precision scanning laser system, for maximum accuracy.

The work successfully removed approximately 3mm of material from the journal faces to allow the stainless steel wear plate sections to be fitted. The vertical bearing face diameter was measured accurately during machining using a precision circumference tape, while the flatness of the horizontal bearing face was within 0.15ram and was independently verified using the precision scanning laser system.

The set-up, machining, and fitting of the stainless steel liners and the replacement of the bearing took nine days working in 24 hour shifts to complete.

A Furmanite technician prepares the journal face and checks the specialist self-milling machine is in position.

Commenting on the work, First Hydro Company's Mechanical Engineering Manager, Bill Moss said: "We called on Furmanite because they have done excellent work for us in the past, especially on the bottom cover of one of the units. Again, in this instance, work was completed quickly and efficiently, we encountered no problems and the machining was extremely accurate. We are delighted with the results."

Hydroelectric smelting plant gets an upgrade Alcan, one of the world's major aluminium companies, believes in doing things in-house. The company owns its own bauxite mines, alumina refineries and smel- ting plants powered by hydroelectricity. Gilkes Limited, a UK-based specialist in small hydro and power recovery applications, knew they had a big job on their hands, therefore, when AIcan called them in to upgrade their smelting plant in Lochaber, Scotland.

I IIIII II I I

Gilkes has recently completed its power generation solution for the Kinlochleven plant with the installation of a third and final 10MW Francis turbine and generator, which generates electricity from a head of 278m at l O00rpm. The Alcan contract included the design, manufacture, supply, installation, commissioning and performance testing of the Gilkes Francis turbines, GEC Alstom generators, main inlet valve, hydraulic controls, turbine

controller, lube oil system and special inlet pipe work.

The challenging project started last year with the installation of the first 10MW Francis turbine, which had a simple PLC speed control to ensure synchronisation with the electricity grid. Phase two required the replacement of the PLC speed control with a Gilkes digital speed governor that now controls all three I OMW Francis turbines~

www.worldpumps.com WORLD PUMPS July 2001

The three main IOMW Francis turbines can now operate either synchronised with the grid or in 'island' mode, the benefit being that the Lochaber smelter is protected should the grid fail. When required, the synchronous generators can also supply power factor correction into the grid system.

The three 10MW turbines are low specific speed Francis machines with their stainless steel runners

mounted directly onto the extended generator shaft. This direct mounting arrangement gives a compact plant layout. All the turbine shaft Ioadings are taken by the generator bearings, which necessi- tated close liaison with Atstom, the generator manufacturer.

In addition, the project involved a full hydraulic analysis of the existing penstock system to ensure penstock pressure rise under all operational conditions remained below the permissible design limitations. As a result a substantial flywheel was incorporated to limit rate of speed rise and corresponding flow reduction in the penstock system. Tests carried out during the commissioning of the plant confirmed the accuracy of the design and validity of the control software.

Careful design of the new inlet pipework was essential to minimise the forces transmitted to the existing penstocks, which are supplied from nearby Blackwater reservoir. Flow to each 10MW Francis turbine is from two existing penstocks and combined in a fully constrained 'Y' piece. Additionally, a lateral compensator fitted down stream allows inlet pipework movement without subjecting the turbine to transmitted pipe work forces.

Cogeneration plants get unique pumping solution that can handle LPG at low pressure

The search for a reliable method of pumping Liquefied Petroleum Gas (LPG) at 30bar of pressure has led Alstom Power UK to purchase seven dual pump packages from Sterling Fluid Systems. The package has been used to provide fuel for seven gas turbines that have recently been installed for AK Enerji in Turkey for utilisation in cogeneration power plants.

Conventional gas turbines require LPG to be pumped at pressures in the order of 70bar and use slow speed positive displacement pumps with their associated pulsation and reliability problems. To meet AK Enerji's needs and enhance the reliability of the cogeneration plants Alstom's fuel system has been designed with a burner temperature control

system. This ensures that the LPG remains liquid at pressures comfortably below 30bar, which is the maximum system pressure, thus allowing the use of a tandem side channel pump.

The Sterling pumpsets comprise a multi-stage AEHA side-channel pump and a multi-stage

wo LD P . - - P s Jo,y2001 wwwwor, pon/ps corn