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關鍵技術

ECOVE Introduces Shock Pulse Boiler Cleaning Technology to Boost Boiler Efficiency and Availability of EfW Plants

ECOVE makes an effort to improve resource cycling efficiency. In this column, taking slag accumulated in the boiler of Energy-from-Waste(EfW) plants for example,represents that ECOVE has become Taiwan's first provider of resource cycling services successfully introducing portable shock pulse boiler cleaning technology to improve boiler efficiency, and increase the amount of waste treatment and power generation.

Poor Original Design Increases Operating Costs in Ash Cleaning

The formation of clinker and slag in the boiler of EfW plants is a complex physical and chemical reaction, involving combustion reaction, fluid mechanics, heat transfer, mass transfer, compound characteristics and interactions. Compared with standard fuel such as coal and natural gas, the fuel of EfW plants is inferior, diverse,and variable waste. That is why the clinker and slag accumulated in the boiler of EfW plants is more serious than that in the boiler with standard fuel.

Due to original designed narrow pitch, ECOVE had also suffered from the blockage of flue gas ducts by the ash accumulation between the superheater tubes (Fig.1 and Fig.2), caused flow resistance of the exhaust gas,led an induced draft fan into failure, and reduced the amount of waste treatment and power generation.As a result, it was necessary to shutdown the boiler to clean ash manually, increased the difficulty in waste management by government. 

Figure 1. Ash accumulation on the superheater.

Figure 2. Ash accumulation under the superheater.

Then, the surface of the superheater for heat transfer also occurred serious ash accumulation causing poor heat exchange. The temperature of boiler and exhaust gas went high and resulted in negative impact on boiler efficiency, life cycles of superheater, and other equipment. As a result, it was necessary to consume diesel oil to startup the boiler, increasing operating cost and frequencies of startup-shutdown which might reduce the life cycles of boiler and refractory.

Thereby, ECOVE staff members had to do the boiler ash cleaning with handwork and pneumatic tools in the narrow confined space among the superheater bundles. Although equipped with complete safety protection, staff members still had to endure the flying ash and annoying noise which caused poor efficiency in ash cleaning.

Introducing Shock Pulse Boiler Cleaning Technology to Boost Efficiency

ECOVE referred to numerous on-line technologies, then collected "shock pulse cleaning technology" as the best solution for boiler cleaning. ECOVE went on to analyze the strong and weak between "portable" and "fixed" shock pulse cleaning technology, and adopted portable shock pulse cleaning technology, with the advantage of free selection of cleaning area, for test and verification at first stage. 

ECOVE staff members took one specially-designed lance with fuel bag and put it into the boiler to the target to clean. And then the fuel bag was filled with gas fuel, ignited to generate gas shock pulse to remove the accumulated ash. After adopting shock pulse cleaning, ECOVE successfully removed the ash accumulation on the superheater bundle. Instead, a clean surface of superheater bundle can be seen. The obvious difference is shown in Figure 3.

Figure3. The superheater before and after cleaning (right).

Why ECOVE ?

ECOVE is Taiwan's first provider of resource cycling services successfully introducing portable shock pulse boiler cleaning technology to improve the boiler efficiency

In 2018, ECOVE went on to introduce fixed shock pulse cleaning technology to maximize the performance of ash cleaning. Both portable and fixed shock pulse cleaning technologies were integrated in order to find out the best operating mode to completely replace the manual cleaning.

Since the application of shock pulse cleaning technology, the efficiency of EfW plants operated by ECOVE have greatly improved and ash accumulation is resolved. Besides, with improvement of boiler efficiency, waste treatment capacity and renewable energy generation have also increased significantly. Last but not least, times to shutdown boiler and the risk of manual cleaning in confined spaces have been effectively reduced.