During the Christmas season in 2011 I went on a business trip to Europe. My initial plan was to visit some business sites in Germany and Austria for a technical exchange. However, just as I was about to return to China, I changed my mind after a phone call with a member of our sales team who was in Europe with Yong Mill customers. He mentioned that he was going to visit Arcelor Mittal. The idea of visiting the world’s leading steel and mining company intrigued me so much that I decided to visit them instead of going back home. And thanks to this spontaneous trip, I discovered an energy saving solution that could be applied to steel mills in China.
At Arcelor Mittal, I saw the amazing energy efficiency that resulted when ten Jenbacher engines worked together. This has high portability and development potential for steel mills in China on several levels. First, Chinese steel mills emit a significant amount of waste gas. At the same time, they are under tremendous pressure from national regulations to conserve energy and reduce emissions. If we put in a place a successful pilot project, subsequent projects would have an equally positive impact.
Using the workflow from Arcelor Mittal and my experience working with Chinese steel mills, I first recognized that many engines working together would reduce more energy than one gas turbine working alone. That led me to think about the gas engine block solution, which provides greater flexibility and energy efficiency than gas turbines can provide. In today’s steel mills, it is common for the flow rate of waste gas to vary considerably. So operating one gas turbine up to full load is very difficult. But with the gas engine block solution, shutting down a few of the engines when gas flow is low would enable the other engines to operate at full load, to optimize efficiency. Additionally, while a gas turbine usually requires a large area of structured industrial land, which cannot easily be obtained in China, the gas engine solution is more flexible regarding floor space needs, so would attract more interest from Chinese steel mills.
We were uncertain, however, how to turn this idea into reality. Without the large market of converter gas available in Europe, we looked at the more easily accessible Blast Furnace Gas (BFG). However, the heating value of BFG is less than one-tenth of natural gas. As a result, the low H2 content led to incomplete combustion.
Numerous measures to increase H2 concentration were rejected because of high cost. We had to come up with the simplest WGS (water-gas shift) reaction to increase the percentage of H2. The next step was to design a combined cycle to utilize gas engine exhaust and gas off heat. About 2.8 MW power can be generated in the combined cycle.
The first BFG engine block solution demonstration will be set up in the Yong steel mill this year, and the output of this pilot project will be 8 MW. The big idea coming from my unexpected detour will eventually open a totally new market for our distributed power business. The trip may have been fortuitous, but our effort is not.