COTES successfully tested a new oil-free ignition technology for coal-fired boilers on the 5 MW firing test facility
The team of COTES Engineering carried out open hot tests of a new oil-free ignition technology for pulverized coal boilers, that will allow total removal of the need for black oil system, including in case of ignition of low-reaction coals. The representatives of several Novosibirsk companies and universities came to the Thermal Physics Institute of Siberian Branch of the Russian Academy of Sciences to see the results of tests on the 5 MW firing test facility.
History of plasma ignition technology
Black oil, the cost of which has become considerably higher, is still used almost by all Russian plants to ignite coal-fired boilers, as a reserve fuel in case of main fuel supply interruptions, and for lighting (at low loads and in case of main fuel quality deterioration). All over the world everyone tries to find a substitute for black oil, not only because of high costs of servicing the oil system itself, and permanent deterioration of the black oil quality caused by a higher oil refining depth, but also in order to minimize negative environmental impact.
The use of plasma technology as an alternative to black oil was proposed and tested yet in several different boilers in the USSR. However, the promising technology of boiler ignition at a cold state without the use of high-reaction fuel has not been implemented for technical and technological reasons.
Chinese experience in application of plasma ignition
After technical advances of electric-arc plasma jets the plasma technology became popular in China, where more than 700 power boilers are equipped with plasma ignition system. There is a series of power plants turned to the oil-free operation in the country: Dongsheng TPP (2 power units of 330 MW), Kangping TPP (2 power units of 600 MW), Fujian TPP (2 power units of 600 MW), Huanjing TPP (2 power units of 600 MW), and Fukang TPP (2 power units of 150 MW). However, the technology applied by China features a high percentage of mechanical carryover of the coal-dust mixture, which is higher as far as the power is increased. Because of that not only efficiency of the technology, but safety of its use is a challenge.
Limitations of the plasma ignition system
Low cost efficiency is among other reasons restricting the technology implementation: the system is oriented to boiler ignition and low number of startups only and can be used during a short time just for the flare catch up and fire stabilization. It also has operational features: special requirements for cooling system, plasma forming air, low continuous service life of several hundreds of hours; the need for a separation transformer, high energy demand.
Electroionization technology by COTES
More than 10 years ago COTES Group of Companies led by Feliks Serant, D.Sc. in engineering, has started developments of a new oil-free ignition technology, requiring no powerful feed source and aimed at fire stabilization of coal-dust fuel. In 2009, the first patent was issued for the invention of a coal fuel ignition apparatus. Today, COTES Group has more than 5 patents for inventions of that technology, with 3 more applications for patents made in 2020. The solution invented by COTES Engineering allows ignition of coal-dust fuel with high moisture and low volatile components content at a minimum specific energy demand.
The technology is based on an electrochemical ignition mechanism by intensifying ionization processes in the boundary layer at the base of the flare. Diffuse electric discharge affecting the pre-flame flare area ensures heterogeneous chemical reactions at low temperatures before volatiles exit, which allows igniting cold air mixture and provides burning of low-reaction fuel as a flare. The technology has already been tried in thermal power plants of Irkutskenergo and Krasnoyarskaya GRES-2 (successful tests of oil-free ignition of coal dust in one burner device of BKZ-420 boiler with the evaporation capacity of 420 t/hour).
At present time, COTES Engineering offers implementation of the oil-free ionizing ignition of pulverized coal boilers on the turn-key basis, including retrofitting the design of a burner itself, feed source, as well as connection of own monitoring system built-into DCS of a power plant.