Damage and causes2 min08.07.2026

Slagging in the biomass boiler: the surface determines the cleaning intervals

In a biomass boiler, ash deposits are rarely the real problem — the problem is how quickly they come back. Five levers from biomass CHP projects.

$Interior view of a biomass boiler with a monolithically compacted refractory lining$

In a biomass boiler, ash deposits are rarely the real problem — the problem is how quickly they come back. In many plants, slagging is accepted as unavoidable. Yet the surface of the refractory lining plays a major part in determining how firmly slag and alkali deposits take hold — and therefore in determining the cleaning intervals.

Five levers from our biomass CHP projects

A dense surface instead of porosity: a smoothly finished, monolithically compacted lining offers slag less to attack.
Material selection according to flue gas zone: chlorine and alkalis load the hot area differently from the afterburning area — the materials are specified to suit each zone.
Minimise joints: every joint is a potential deposit site. Prefabricated components reduce the number of joints.
Prefabrication in Putzbrunn: critical components are cast and dried in our workshop — during the shutdown they are simply exchanged. That saves days.
Document the cleaning intervals: whoever records when and where slag builds up plans the next overhaul instead of suffering it.

The result: longer cleaning intervals, plannable shutdowns, higher plant availability.

At a glance

5 levers

adjusting screws against rapid re-slagging

Prefabrication

components from the Putzbrunn workshop save shutdown days

Ash and slag: the enemies of the refractory lining in biomass plants

5 minRead

$Refractory-lined combustion chamber of a biomass power plant with visible brickwork$

Lining and materials

Materials technology in biomass power plant combustion chambers

5 minRead

View into a freshly lined combustion chamber with arch and grate

Lining and materials

The combustion chamber from the inside: what matters when lining the hottest zone

2 minRead

From practice

Matching references

Combustion chamber refurbishment in a biomass power plant

Fundamental overhaul of the combustion chamber of a biomass power plant – including renewal of the side brickwork, new expansion joints and thorough cleaning for optimised efficiency.

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