The present invention relates to boilers comprising solid waste burning u?iis; which, in wet systems, consist of stationary and mobile sliding bearings with tubular system water conduits and wherein, in waterless system, the stationary sliding bearings comprise tubular system water conduits and the mobile bearings are preferably made of heat resistant metal or ceramics. Water tubes (3) are welded on lamas (2) with holes to form sliding bearings with tubular system water conduits. A mobile sliding bearing is designed as a step to be arranged in between two stationary sliding bearings. |