ArcelorMittal has announced that, for the first time in Poland, two top pressure recovery turbines (TRT) will be reusing high pressure flue gas from the top of the blast furnace to reduce ArcelorMittal’s carbon footprint – and its energy bill, while producing emission-free energy for TAMEH power plant in Dąbrowa Górnicza.
Two 81-tonne turbines, made in Japan, and shipped in containers 4.5m wide; 5m high and 8m long are being assembled before being mounted to modernised blast furnaces operating in Dąbrowa Górnicza, Poland. The turbines will increase the amount of energy the power plant generates, at no extra cost and without emissions.
Producing electricity using TRT technology is as sustainable as wind power, but much more efficient. The two new TRTs’ total capacity of 25 MW, is roughly equivalent to the output of eight to ten land-based wind turbines. To produce the same amount of energy from coal, it would be necessary to burn 52,000 tonnes of it annually, or 900 wagons worth. The associated emissions would amount to 90 tonnes of sulphur dioxide and nitrogen oxides and nine tonnes of dust.
TRT technology uses high-pressure gases (known as flue gases) which collect at the top of the blast furnace to drive very efficient electricity generators. The TRT turbine generates energy by exploiting a known property of all gases – that they expand as their pressure drops. Dry and wet scrubbing is used to remove fine particulates from the flue gas as it leaves the blast furnace. At this point, the pressure is between 2.0 and 2.2 bar. After the scrubbing process the gas pressure needs to be reduced to 0.15 bar in the septum valve for further combustion in gas boilers. The most energy efficient way to do this is to lead the gas through the turbine instead of the septum valve to drive a generator to produce electricity.
TRTs have no impact on blast furnace operations and the flue gas is not consumed. As blast furnace gas is very combustible, it is normally used in other parts of the plant to generate heat or energy for other processes. With the TRT system installed, the flue gas effectively generates energy twice – once in the turbine and again when it is burnt for its usual purpose.
“Until now, the TAMEH power plant produced energy out of blast furnace gas, but only after reducing its pressure. Now, where we used to reduce that pressure, we will install the TRTs, which will be powered by the compressed blast furnace gas to produce energy that would otherwise have been lost,” explained Artur Łój, project manager in the Investment Office, TAMEH Polska.
“After completing assembly of the TRTs, it will be necessary to install the generators, pipelines, and connect the turbines to the blast furnace gas installation. We have aligned our assembly dates to blast furnace operation schedules to take advantage of planned standstills to avoid disturbing work flows,” Artur Łój explained.
The investment, to be finalised this year, is worth over PLN 100 million. The project’s general contractor is a consortium comprised of Primetals and Eko Energia from Kraków. Many companies from the region are also involved in the project, with about 100 people working at the construction site each day.
Implementing TRT is part of ArcelorMittal’s ongoing commitment to research and developmental improvements to its processes to ensure technological superiority in the use of energy and raw materials. This reduces manufacturing costs, improves quality and minimises the company's environmental impact. TRT also provides ArcelorMittal with security over the sustainability of its long-term energy supply, and reduces its exposure to rising energy prices.
TAMEH HOLDING (TAURON ArcelorMittal Energy Holding) is a joint venture between TAURON Group and ArcelorMittal Group, where each company holds 50% of the shares.