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30 : Novel research projects

30 : Novel research projects

Jérôme Favergeon, director of UTC’s Mechanical Engineering Department, who heads the PROCCI Project describes the work ahead: “In order to comply with the European waste valorisation objectives, we have to increase the incinerator temperatures, but in doing so we run the risk of higher corrosion in the heat exchanger units”.
The latter (exchange units) are sets of metal tubes located over the waste furnace, and the waste burning heats water vapour passed through the tubes. The steam is then used to feed a turbine-generator and the electricity produced is fed into local collective building heating networks.

Resisting ashes, oxygen, chlorine and sulphur

Incinerating wastes also produces ashes, oxygen, sulphur and chlorine. “The ashes adhere to (and build up on) the tube inner surface, which are also attacked by the acid gases. This sequence of events requires regular inspection tours and costly pipe changes during which down-time the plant cannot be used. What we are seeking is better tube protection and at the same time retaining the initial heat transfer capacity to the water vapour”, explains Jérôme Faugergeon.
Our aim is to gain better understanding of the corrosion processes so as to be able to counter them and we do this by adding 3-4 micron ceramic coatings. The latter derive from a sol-gel process developed by CETIM and analysed by the UTC Roberval Laboratory but the dual question remains – how and how long will they resist corrosion agents? How will the coatings react as the tubes dilate with rising temperatures? Will they be able to resist if the inner surface are slightly pitted?

Increasing tube life expectancy by at least 20%

After facing several difficulties to produce the sol-gel coatings a continuous flow, the first characterization tests in incineration environmental conditions will begin in Autumn 2014 at the UTC-Roberval laboratory. “We can bear in mind that the PROCCI Project began in October 2012 and we shall surely be in a position, to present an attractive solution by early 2015, a few months before the project schedule terminates; energy procurement and uses are among the Region’s priorities in terms of research topics, and the Region has awarded a 150 000€ financial support”, adds Jérôme Favergeon.
UTC has also contributed 150 000€ and CETIM the rest. In order for the solution to be economically worthwhile, we must be able to increase life expectancy of the tubes by at least 20%. “For the time being, we note that there only a few studies on the problem and it will become more acute as the need to identify and use alternate energy sources grows. Veolia Environment have shown interest in the project. If the coatings we are developing turn out to be scientifically and economically attractive, their use could be extended beyond the field of industrial incinerators”, underscores Jérôme Favergeon.

Extending incinerator operational life expectancy