Saving energy by optimized afterburning
Steel production is one of the most energy-intensive industrial processes. An electric smelting furnace requires some 450 kWh of electrical energy to smelt a tonne of metal. Optimized afterburning is able to reduce this energy demand by up to seven percent. This involves adding oxygen to the melt in order to convert the carbon monoxide generated into carbon dioxide by afterburning. The combustion heat is utilized for the smelting process. The better the concentrations of CO, CO2 and O2 are matched to one another, the more efficient the afterburning process will be. Fraunhofer IPM has developed a system that measures the concentrations of the gases in the arc furnace, thus making optimum process control possible. The system draws a sample of the gas mixture from the smelting furnace by suction. In less than ten seconds, an IR spectrometer determines the concentrations of CO, CO2 and O2. This enables the process parameters to be readjusted and the process to be optimized. The sensitive measurement technology functions reliably even under the difficult measuring conditions in the steelworks.
Fast infrared measurement techniques for process analytics
Infrared spectroscopy is an important tool for research and industry. This particularly accounts for the mid-infrared wavelength range > 3 µm with its large molecule absorption bands. So far, expensive and cryogenically cooled detectors have been necessary for sensitively resolving mid-infrared features, e.g. when monitoring chemical processes. By using nonlinear frequency conversion, mid-infrared radiation (MIR, e.g. 3-5 µm) can be converted into shorter wavelengths in the near-infrared range (NIR) where silicon based detectors and cameras can be employed. These systems are significantly faster, cheaper and more sensitive.
Such a wavelength range extender for NIR spectrometers makes the advantages of silicon detector accessible for the MIR spectral range. This enables monitoring of fast chemical processes by taking infrared spectra at high frame rates. Conventional MIR systems, e.g. grating-spectrometers or Fourier-transform-spectrometers, with acquisition rates of typically 100 spectra per second are too slow for this kind of process monitoring.
Our range extender is able to resolve spectral information from mid-infrared wavelengths with high resolutions of 2 nm at an acquisition rate of 6500 spectra per second. This is fast enough to observe processes such as the gas evolution at the detonation of an airbag gas generator in real-time, to name but one example.