Partnership with a forward-looking utility, Helsingborg Energi, is enabling ABB Alstom Power to prototype test its new GTX100 gas turbine in a real power plant under commercial conditions.

The 18th of November saw a major milestone in the development of ABB Alstom Power’s GTX100 gas turbine when the prototype was taken to full load for the first time during an extensive test programme currently underway at the Västhamn plant of Helsingborg Energi AB (HEAB). The plant is located in industrial southern Sweden, a quick helicopter hop from Copenhagen across the Öresund. The broad conclusions from the tests to date would appear to be so far so good.

The heavily instrumented prototype, festooned with connections to some 1500 measuring points (recording temperature, strain, pressure, performance, sound levels and emissions), has been undergoing load tests on fuel gas. The next phase of commissioning will be transient handling tests, to be followed by a trial run and then tests on fuel oil, including gas/oil changeover, with commercial operation due in 2000. Events at Västhamn are being monitored with more than a little interest from France, where the second GTX100 is under commissioning at a pulp and paper mill (Emin Leydier), a few weeks behind the Västhamn unit.

Achieving commercial operation of the first GTX100 will mark the culmination of a development project launched by ABB in 1994. The aim was to address what it saw as a growth market, and still does (despite a dip in the past two years): IPPs and industrial power plants looking for combined cycle and cogeneration systems. It also wanted to plug a gap in its product range, a machine in the 40 MW class.

In simple cycle baseload operation on natural gas the basic ratings (ISO) of the GTX100 are: power, 43 MWe; SHC, 9720 kJ/kWh; efficiency, 37 per cent; and exhaust mass flow and temperature, 122 kg/s and 546°C. In combined cycle mode, power is 62 MWe and efficiency rises to 54 per cent or more. On natural gas, emissions are 15 ppmv for both NOx and CO (@15 per cent O2), while for liquid fuel the figure is 25 ppmv.

The GTX100 was introduced to the market in 1997 (see Modern Power Systems, July 1997) and from the outset reliability has been underlined as a key goal, achieved through simplicity and robustness, validation based on extensive calculations and testing, and use of proven components and design concepts. All the major components have antecedents in previous ABB gas turbine models. The GTX100 is “new and yet not new”, says Bertil Nilsson, Manager, Strategic Development, ABB Alstom Power, Finspong, Sweden.

Other features of the design are compactness (footprint of 27m x 7m), ease of construction, with maximum standardisation and modularisation, and ease of maintenance. The gas turbine is designed to be easily removable from either side of the plant, for example. Overall, maintenance costs are estimated to be fairly low: in the region of US$1.5/MWh.

More power to Västhamn

At the Västhamn CHP plant the GTX100 turbine plus HRSG is being integrated into an existing boiler plus steam turbine system, which already provides district heating and generates electricity. The new gas turbine block is being built adjacent to the existing CHP plant, which burns coal and, increasingly, wood pellets – the Västhamn site boasting the largest wood pellet store in Sweden.

The capacity of the existing Västhamn CHP plant is 64 MW electricity and 132 MW of heat (in addition there is a 29 MWt heat pump connected to the district heating system, which extracts heat from waste water). The end result of the GTX100 repowering project, which also includes reblading of the existing steam turbine so it can handle the increased quantity of steam available, boosting its capacity from 64 MWe to 82 MWe, will be to transform the plant into a combined cycle CHP plant producing 126 MW of electricity and 186 MW of heat (excluding the heat pump).

As a development project it has the support of the Committee for Energy Supplies in Southern Sweden (DESS) and the Swedish National Energy Administration, each of which is contributing SEK 16.7 million (US$ 2.13 million) to the SEK 220 million (US$ 28 million) cost. The project is seen as making an important contribution to the transformation of the Swedish energy sector into what is described as an ecologically and economically sustainable system, as laid down in the 1997 act of parliament. It also provides benefits to Swedish industry by demonstrating both the new GTX100 turbine – which occupies a sector of the market with estimated sales of about 100 machines per year – and the feasibility of converting an existing steam plant to combined cycle. There are good precedents. In 1991 the Swedish government gave financial support to the first GT10 combined cycle installation with low NOx technology, at Ängelholm. Since then more than sixty have been sold, many of them as part of turnkey projects, amounting to about SEK 5 billion worth of business.

An immediate benefit from the new plant at Västhamn will be to help make up the capacity shortfall created by the closure of the nearby 600 MWe Barsebaeck 1 nuclear unit – and indeed this was a primary driver in HEAB’s initial planning (closure of the Barsebaeck boiling water reactor finally took place on 30 November). Other advantages of the repowering include: more effective use of the existing southern Swedish natural gas network; more effective use of the existing Helsinborg district heating network; and, looking at HEAB’s overall system, significantly reduced emissions.

Biogas and biomass

HEAB, currently wholly owned by the city of Helsinborg, but likely to be partially privatised in the near future, has impeccable environmental credentials, a good track record for innovation and seems to feel very much at home in the brave new world of the deregulated Swedish electricity market. It sees a growing role for district cooling (even in southern Sweden), hopes to use its powerlines for telecommunications and has a very diversified and complex fuel mix, including coal, wood, oil, natural gas, waste heat, landfill gas, hydro and a small amount of wind.

In the future HEAB sees biogas playing an increasing role in the mix, as well as natural gas, and in its continuing development work on the GTX100, ABB Alstom Power is working on the combustion technology to expand the range of fuels to include lower energy content gases. So in the not too distant future, and with HEAB’s track record for innovation, we might see the GTX100 at Västhamn running on bio-gas or gas from biomass.

GTX 100 – orders to date