Novosibirsk State Technical University has proposed an environmentally friendly and economical approach to igniting pulverized coal fuel. The new technology will reduce emissions of harmful substances into the atmosphere and ensure more complete combustion of coal, which will increase the efficiency of the combustion process and reduce the total amount of fuel used.
The developers were faced with the task of kindling a pulverized coal boiler without using highly reactive fuel, mainly fuel oil. As Denis Sinelnikov, associate professor of the Department of Thermal Power Plants at NSTU-NETI, Candidate of Technical Sciences, notes, fuel oil is a residual product of oil refining — it is formed after lighter fractions (gasoline, kerosene) are isolated from the oil. As a by-product, it used to be cheap and was one of the most economical types of fuel for boilers and industrial furnaces, but with an increase in the depth of oil refining, it actually ceased to be a free fuel. In addition, when burning fuel oil, many harmful substances are released into the atmosphere, which damages the environment.
"The pulverized coal fuel electric ignition system is a power source that has the following characteristics: a voltage of about 10 kV, an alternating current frequency of 10 to 40 kHz. Voltage is applied to the electronic units installed in the burner device. An electric discharge of alternating current with the above frequency is formed between the electronic blocks, which are copper cylinders. Due to the physico-chemical properties formed in this electric discharge, it is possible to influence the root zone of the pulverized coal flare — it ignites and burns steadily," Denis Sinelnikov said.
The technology, based on the effect of a high voltage and high frequency electric arc on the dust-air mixture, provides ignition during boiler kindling, and can also be used in plasma systems for fuel pretreatment in order to increase combustion efficiency and improve environmental performance. Due to electric ignition, the amount of harmful substances released into the atmosphere, such as soot, sulfur dioxide and nitrogen oxides, is reduced.
Currently, this technology is being implemented in the territory of the Republic of Kazakhstan, where low-reactivity, balastered coals are used. They are cheap, but they contain up to 50% ballast, i.e. non-combustible substances, and they are very difficult to burn. As the scientist notes, the possibility of ignition of such coals has been confirmed. Denis Sinelnikov added that industry colleagues are implementing similar technology in Novosibirsk, Irkutsk and Krasnoyarsk.