Precise temperatures for greater process control in the blast furnace

The production of iron and steel causes high temperatures and a high energy demand. The temperature distribution at the top of the blast furnace is a key parameter for the reliable and efficient control of this complex process.

Reliable and precise measurement in harsh environmental conditions

At the top of the blast furnace directly above the burden column there are very unfavorable conditions for accurate measuring instruments. High concentrations of CO in the blast furnace gas, which has about 1 to 2 bar overpressure at the top of the blast furnace, make a direct insight into the top of the furnace nearly impossible. Each measuring element which extends into the blast furnace is exposed up to 25,000 tons of falling raw materials daily.

In such harsh environmental conditions the acoustic gas temperature measurement shows its advantages. Since 1991, our system has been working effectively in waste incinerators and coal-fired furnaces. All components are located outside the furnace and therefore significantly less exposed to the harsh environmental conditions inside than other methods. Therefore, our system operates nearly wear- and maintenance-free. The feed of the blast furnace from above is not adversely affected.

Measuring the „real“ gas temperature contactless

In the blast furnace, the system uses nitrogen instead of compressed air in order to generate the acoustic signals required for the measurement. Interactions with the furnace process can thus be excluded safely. The measurement is performed contactless and is (inherently) free from radiation effects. Only the “real” gas temperature is measured. There is no drift, therefore a calibration of the system is not required.

Early detection of channels due to fast 2D measurement

High resolution 2D temperature distribution at the top of a blast furnace
High resolution 2D temperature distribution at the top of a blast furnace

From a variety of measuring paths, the system calculates the two-dimensional temperature distribution over the entire measuring plane by using tomographic methods. The measurement is not subject to inertia and always provides the actual gas temperature at every measurement cycle. The result is a temporally and spatially high resolution of the temperature distribution (regarding time and space) at the top of the blast furnace. Sudden formation of high temperature layers (so-called channeling) can be detected early enough to take countermeasures in the charging of the blast furnace top through the chute. Thus longer furnace shutdowns can often be avoided.

From R&D to a reliable and safe industrial standard

The acoustic temperature measurement at a blast furnace top was first carried out in 2003. As part of a research project with ThyssenKrupp Steel AG, we conducted first tests at the ThyssenKrupp plant Hamborn. After successful results, we installed a complete two-dimensional measurement system. The results and experiences were published in the German journal Stahl und Eisen in 2009.

In the field of iron and steel, we offer the acoustic measurement technology together with our partner TMT – Tapping Measuring Technology under the name TMT SOMA. We have already equipped more than 20 blast furnaces world-wide with the system.