Water Cannons for cleaning membrane walls of a 600 MW lignite-fired steam generator
Author:
Dipl.- Ing. Jochen Müller
Published:
„VGB – Kraftwerkstechnik (2000) Nr. 12“
Edition:
2002
Summary
The steam generators run in the base load mode at the Weisweiler Power Plant are supplied with fuel from the Inden open-pit mine. Excess flue gas pressure from possible hot standby operation has not been considered in the design of heating surface cleaning. At the Weisweiler Power Plant water cannons are used for cleaning the furnaces of the minor steam generators. The furnaces of the 1900 t/h steam generators G/H are cleaned by Water Lance Blowers (WLB). For this purpose already in 1992 a test WLB was installed and numerous measurements were made to determine the wall temperature load during cleaning by water lance blowers. At the initial stage four water lance blowers were fitted in each boiler for cleaning the evaporator helix between +64 m and +46 m. At the second stage another four WLB's were added per boiler for cleaning themembrane walls in the burner area between +46 and +17 m.
Conclusion
As a result it may be stated that also at the reference units of the other power plants the water lance blowers cover the whole area of the furnace and clean it efficiently while here the existing water lance blowers were not yet dispensed with. At present experience is being acquired with the use of platen cleaning programmes and others for cleaning the flue gas recirculation heads; in an initial approach they are very promising. The important valuation factors shown in the following overview should be taken into account for the assessment of the economic efficiency of a new installation of eight water lance blowers in each of the boilers G/H in comparison with the conventional operation with overall 116 SK58 water cannons. The factors were referred to the costs of the water lance blower installation. These input parameters of the economic efficiency analysis resulted in a pay-back period of about seven years.
It should be noted that according to the latest operating experience it is possible to save 116 water cannons instead of 100. At the Weisweiler Power Plant and also at the three other lignite-based power plants the operating experience acquired with the water lance blowers are valued positively. There is however still some potential for optimisation of the cleaning intervals fixed merely as a function of time. The operating mode of the water lance blower adapted to the fouling state would be an optimum solution for this. Such diagnostic systems for the furnace would make cleaning by means of water lance blowers still more efficient. Coupling of these "Furnace diagnostic systems" with already existing optimisation systems for boiler cleaning such as Kedi, Dora and SR4 would be ideal in the sense of boiler cleaning oriented by the fouling state.
For more informations please request the original experience report !
