A team of scientists at a mining research center in Katowice, southern Poland, has designed an innovative device that instantly measures the content of ash in coal with no need for time-consuming chemical analysis. This helps save time, money and energy.

The device, dubbed Walker, won a gold medal at this year's 106th Concours Lepine international invention competition in France. Last year it claimed a gold medal at the 55th Eureka World Exhibition of Innovation, Research and New Technologies in Brussels, where the judges appreciated the Walker's practical value, alongside its innovative technology.

The Walker is used to determine the content of ash in samples of coal or other solid fuels such as lignite, and to calculate the fuel's heating value in this way. The device determines the content of incombustible matter in a coal sample on the basis of the natural gamma radiation found in coal. Before the ash meter was designed, the measurement of ash content in coal was a time-consuming process. Samples were collected in storage yards or coal cars and taken to a laboratory, where they underwent chemical analysis. The results were usually obtained the next day.

The Walker measures the content of ash in coal without the need for chemical analysis, and thus makes it possible to save time, money and energy. In old ash meters, the source of radiation was an isotope. The quality of coal was determined by measuring the intensity of the radiation beam reflected from the coal sample or the intensity of the beam after it has passed through the sample. This, however, posed a threat to the environment, and researchers looked for methods that would enable them to give up the use of radioactive materials. The Walker, an isotope-free device in which measurements are based on natural gamma radiation, is such a method.

"Just 20 years ago this radiation was impossible to detect because there were no devices that could do that," says Teresa Sikora, head of the team of researchers who designed the Walker. "We have been designing various control and measurement devices for many years. In the past, these were mostly isotope devices that used an artificial source of radiation. Eight years ago we became specialized in an isotope-free measurement technology based on natural gamma radiation. We developed the Walker as part of a special-purpose project in 2002-2003 and we managed to put it into production almost immediately."

The Walker is a small, portable device that weighs only 7.5 kilograms. It enables fast, precise and fully automatic measurement of coal ash content in storage yards, silos, coal cars and trucks. Previous methods in which samples were analyzed by means of chemical analysis were often inaccurate, depending on where the sample had been collected. Moreover, researchers had to analyze a much larger number of samples to increase measurement accuracy. With the Walker, the results appear on an electronic display in less than 20 seconds and are entered in the memory of a microcontroller. The data can be sent to a computer, and the user can choose the language version of the messages on the display. The device can work in temperatures ranging from minus 10 degrees Celsius to plus 50 degrees.

The Walker provides a quick quality assessment of raw, processed and screened coal as well as coal delivered to a power plant. Most of the devices sold so far are used in Polish mines and heat-and-power generating plants. But the Walker has also attracted buyers abroad-in countries such as Russia, Vietnam, Turkey and Ukraine, with the producer also eyeing the Chinese market.

The price of the ash meter, around zl.42,000, includes the cost of calibration/scaling. A team of engineers at the EMAG Center provides on-site calibration services because the natural radiation values of coal differ depending on the deposit. As a result, coal from individual mines has different calibration curves. The user can enter 16 different curves in the microprocessor's memory.

The Walker has been designed at the Mining Electrification and Automation Center (EMAG) in Katowice by a research team led by Teresa Sikora, M.Sc., and composed of Bolesław Czerw, Ph.D.; Marek Kryca, M.Sc. Eng.; Ireneusz Motyka, M.Sc. Eng.; and Stanisław Rysiecki, M.Sc., Eng.

In addition to international awards, all the members of the team, who work at the Unit for the Automation of Measurement and Processing Devices, have received certificates of distinction from the Polish minister of science and higher education, as well as an award from the economy minister. They also won a medal at the 13th Eltarg electrical engineering, electronics and power engineering exhibition in Katowice in 2004.

Ewa Dereń