The world’s steel industry is power-hungry. Using energy both to supply heat and power for plant operations and as a raw material for the production of blast furnace coke, the sector uses a major fraction of the world’s total energy consumption. China’s steel and iron sectors have been mushrooming on the back of skyrocketing demand, fed by an economy that has been growing at 9% annually for 10 years.
According to Chinese academics, the nation’s steel and iron manufacturers’ energy demand reached more than 490 million tons of coal equivalent—or more than 17% of the total national energy consumption in 2008. China’s iron and steel industry produces 11% of its total carbon dioxide emissions (compared to 5% worldwide). They also suggest that 95% of these emissions are caused by combustion of fossil fuels.
Enter engineers at GE Energy in November, who said they had found “a way to turn some of steel’s biggest liabilities into assets.” The solution involves an improvisation on an old method to convert carbon- and hydrogen-rich waste greenhouse gases into electricity. And they plan to put it into effect in a newly ordered project at the 170-MW power plant at Handan Iron & Steel’s mill in Handan City, China.
GE says that the project will capture, clean, and compress the blast furnace and coke oven gases generated during the steel-making process and feed it to GE’s giant 9E Heavy-Duty Gas Turbine (Figure 4)—a technology that will reportedly produce enough electricity to potentially turn an average-size steel mill into a net power generator.
|4. From parasitic facility to utility. A GE project at the 170-MW power plant at Handan Iron & Steel’s mill in Handan City, China, promises to capture blast furnace and coke oven gases generated during steel manufacture and convert them into power. This image shows assembly of the massive GE 9E gas turbine. Courtesy: GE|
“The plant can go from being a parasitic facility to essentially a utility,” says GE Energy’s Ryan Derouin. “If they are in that utility-island mode, they can start selling power back to the grid or send it to other parts of the plant. It gives the owner options.” The technology also has the potential to nearly halve the electricity cost for Handan, from the market rate of $100/MW to as low as $60/MW, Derouin says. It could also allow the mill to lower costs, boost profitability, and gain a competitive edge, especially in a market with low grid reliability.
The project has been challenging. One issue encountered was that waste gases at Handan vary in quality and contain too little of the heat-packing hydrogen to make the gases burn effectively by themselves. Instead of redesigning the plant, engineers opted to redesign the fuel, finding a clever way to clean, compress, and mix gases to power the huge turbine. “This is the lowest quality fuel we’ve ever even considered burning,” said Keiran Coulton, president of GE Energy, Global Industries.
The Handan project is not unique: In 2010, GE rolled out two GE 9E turbines at Wuhan Iron & Steel, and it claims that so far, the turbines have increased Wuhan’s energy efficiency by 25% to 40% on average and lowered carbon dioxide emissions by about 2 million tons.
—Sonal Patel is POWER’s senior writer.