The boiler is designed with an upper and lower drum. Between these are a vertical water tubes. The tubes are dimensioned to give a defined circulation throughout the whole boiler. The inner part, (the combustion chamber), and the outside part (the flue gas shell), are built from membrane walls and because of the boilers special construction, it can be made operational within short time. For inspection of the upper and the lower drum on the waterside, you will find inspection hatches on the side of the drums. Cleaning of the boiler`s heating surfaces is done by steam sweeping. This equipment is ready installed from works.