Siemens Gas Turbines for Malaysia
It was not exactly crossing Checkpoint Charlie, but the four Malaysian journalists who walked out of Siemens’ gas turbine manufacturing plant in Berlin into a cool drizzle, realised that it was a historical landmark.
As we ended a three-day tour of the engineering giant’s gas and steam turbine operations in Germany, we took a hurried final look at the plant − or more specifically, towards the facade of one of the buildings within this 130,000 sq m manufacturing site.
High up on the earth-coloured wall, where one might expect to glimpse the familiar Siemens logo, we saw instead a hexagonal AEG logo.
AEG, a German producer of electrical equipment, had once owned this factory site (acquired in 1904). Some of the factory buildings have heritage status that requires Siemens to preserve either their facade or entire structure. It could not even remove the AEG logo.
The building’s design for large-scale construction had been revolutionary during its time, with tall glass panels on the sides that allow in natural light.
The walls separating the public from Siemens’ manufacturing operations hold many trade secrets. But the industrial conglomerate also has achieved many new technological feats behind those aged walls that it wants its customers and the public to know.
The modern history of gas and steam turbines – the heart of a power plant – harks back more than a century. The technology, however, is constantly evolving. Siemens is working to push physical and technical limits of these “old” products so that power plants can produce cleaner and more affordable energy from fossil sources.
Malaysia stands to benefit, as Siemens is supplying the world’s most efficient gas turbines − SGT5-8000H − for two power plants currently being constructed here. These are TNB Prai’s 1,017-MW combined cycle power plant, which also uses a Siemens generator (the second of two H-class units has just been shipped) and Petronas’ 1,220-MW Pengerang co-generation plant in Johor (the first of three will be delivered next year).
Siemens will also supply a steam turbine for the Pengerang plant. This will enable the plant to produce up to 1,480 tonnes per hour of steam for the Pengerang Integrated Complex, whose components include the RM89bil Refinery and Petrochemical Integrated Development (Rapid) project.
Siemens has sold 40 H-class series globally, of which 10 units are in commercial operation. It is the market leader for this large-turbine class, which has the highest efficiency and output rating. The SGT5-8000H gas turbine produces sufficient energy to supply a city with about two million inhabitants.
Dr Olaf Koenig, co-ordinator of strategic projects for the Berlin factory, told the Malaysian reporters that the H-class gas turbines have clocked up 100,000 equivalent operating hours (EOH); hence the pioneering technology has been proven. Siemens expects to reach 250,000 EOH by 2015.
He said that even a small gain in energy conversion efficiency rate can slash cost significantly and help save the environment.
A 1.5 percentage point improvement in efficiency equals a savings in fuel gas consumption of 14,700 tonnes annually and a reduction of annual carbon emissions by 41,000 tonnes.
Siemens has been the trailblazer for most efficient gas turbines for more than two decades, but the growth margins in efficiency over the decades were as miniscule as the increments in the men’s 100m sprint record.
Through combined-cycle technology, Siemens hit a 52% efficiency level in 1991. That inched up to 56% in 1996, 58% in 2001 and 60.75% in 2008 with the SGT5-8000H, the world’s largest operating gas turbine. (Combined-cycle refers to the use of two or more thermodynamic cycles, usually combining gas and steam turbines, for better overall efficiency.)
Based on tests, Siemens expects its SGT5-8000H series to break the record again in 2016 for the currently under-construction Lausward power plant in the port of Dusseldorf, with an operating efficiency of over 61%. As a comparison, the efficiency of coal-fired power plants worldwide averaged 33% in 2012, according to International Energy Agency.
Power level, efficiency, cost and construction speed are some of the key considerations for power plant operators in choosing turbines and generators. “In Asia, it is clearly efficiency driven, as it doesn’t have too much own resources for gas and there is also the environmental challenge for CO2 emissions,” Koenig said.
“In Europe, which was our main market for a long time, efficiency was the driver as fuel costs were high; we do not have too many own resources. For North America, which has its own oil, gas and coal reserves, it’s price and power.”
He described three technological challenges in making the turbines: high temperatures, high centrifugal forces and high velocities.
The higher the temperature from the combustion system into the turbines, the more power is given out and the better the efficiency. The limitation lies in the turbine blades’ melting point, so the challenge is in finding cooling schemes. Also, the engine rotates up to 3,600 revolutions per minute; hence strong centrifugal force threatens to tear the turbine blades apart from the rotor. The blade tips also reach high velocities − as they travel at close to sonic speed, the aerodynamics changes drastically and affects the mechanical integrity.
The ceramic-coated gas turbine blades can withstand temperatures of up to 1,516 degrees Celsius. Siemens manufactures power-related products of huge dimensions, with turbines alone reaching up to 440 tonnes.
The huge sizes present some transportation challenges. Hence, it is to its advantage to have factories near rivers, where products can be shipped out. For example, its Muelheim steam turbine plant (Siemens moved its steam turbine operation from Berlin to Muelheim in the 1970s) sits next to the Ruhr river.
But the challenges also come in small sizes. Despite the size of the turbines and generators, much high precision engineering is needed whereby the tolerance level can be as low as 0.001 millimetre (mm). A small deviation such as in insulation could have “catastrophic conqequences”, said Siemens AG head of industrial engineering at the Muelheim facility Dr Henning Rohkamm.
Siemens takes pride not only in its gas turbines but also the older steam turbines.
As Siemens chief financial officer (European utility steam) Michael Beckert said: “The only things that keep us really alive are technology, leadership and synergies. We have to make sure that we (the Muelheim plant) stay as an elite plant in the global network, and that we cascade innovations to other sites.”