NKK to Market New Energy-Efficient
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| NKK's 12 ton-per-day demonstra- tion stoker incinerator |
With the recent completion of three-year performance tests using a demonstration plant, NKK is now stepping up marketing activities for its "hyper 21 stoker system"--a highly energy-efficient new-generation waste incinerator that also minimizes environmental loads.
The new stoker incinerator utilizes NKK's proprietary two-way flue gas combustion system that incorporates "high-temperature air combustion technology," enabling stable combustion of municipal waste. This contributes to optimized energy efficiency and minimized toxic emissions with lower air ratio combustion.
To verify this technology, NKK conducted a series of tests commissioned by the New Energy and Industrial Technology Development Organization (NEDO), in which a mixture of gases--high-temperature air and re-circulated exhaust gas--was blown into the primary combustion furnace. Results showed that the volume of exhaust gas was reduced by some 30% and NOx emissions by 20%, with the other toxins also showing a substantial decrease, compared to current incinerator performance.
The new incinerator also adopts water-cooled hyper grates and new refractory structures, which are expected to more than double grate service life compared to conventional air-cooled systems. The water-cooled grate system provides extremely high cooling efficiency with its simple hollow-cast structure, which is expected to reduce both the stoker furnace size and overall costs.
The advanced incinerator achieves an exhaust gas dioxin concentration below 0.01 ng-TEQ/Nm3 , sufficiently meeting the Japanese government's new regulations (below 0.1 ng-TEQ/Nm3) that come into force this December. Use of high-temperature, high-pressure boilers and heat recovery systems will enable waste-to-energy power generation while reducing CO2 emissions. Furthermore, incorporation of an ash treatment furnace allows bottom ash to be recycled for effective use without polluting the environment.
NKK aims to secure orders for the new stoker incinerator for both new installations and modification projects that entail existing municipal incinerators.
