Rebuilds and conversions

Rebuilds and conversions for energy

Valmet’s rebuild and conversion technologies provide decarbonization solutions. A great number of boiler plants worldwide have been upgraded by Valmet with excellent results. We provide you with expert support and manage complete projects in the shortest possible period of time.


Better fuel flexibility

Increased boiler efficiency

Improved availability and reliability

Reduced maintenance costs and extended boiler lifetime

Reduced emissions

Modernizations for power boilers

We in Valmet’s Energy business unit provide our global clients energy solutions such as boiler and gasification plants, environmental systems and major upgrades of these plants. Our Rebuilds and Conversions technology unit offers modernizations for power boilers. The driver behind a rebuild is often related to changeover from fossil fuels to renewables like biomass or waste. The tightening environmental regulations are also handled with our wide technology offering for emissions control.

Why consider a rebuild?

A rebuild can offer a shortcut to improved conditions. A rebuild can improve your productivity, availability and efficiency. You can widen your fuel flexibility, and you have the possibility to switch to biomass firing or fulfill the stricter emission limits.

Rebuilds are typically conversions from coal firing to biomass firing, and recovery boiler modifications to biomass firing. For example, when building a new recovery boiler for a pulp mill, the old recovery boiler has often been converted to a biomass-fired power boiler.

It is worth ensuring that the technical and process goals of the proposed rebuild also meet the business goals. The good news is that whatever the requirement, there are many options and possibilities to improve both your boiler and your business.

Converting old boilers into bubbling fluidized bed (BFB) technology is an environmentally sustainable solution and can be carried out at a highly competitive cost. A BFB conversion helps reduce emissions and also solves other environmental issues, such as sludge disposal.

BFB conversions

Many types of existing boilers – pulverized-fired, grate-fired and recovery boilers – can be converted to bubbling fluidized bed combustion. After the conversion, the boiler can burn various biomass fuels and industrial by-products. Some portions of the fuel mixture can even be waste or agricultural derived fuels. Gas and oil can be used as supplementary fuels.

Major part of the existing boiler and auxiliaries can be utilised as is. Modernization focuses on lower part of the furnace to introduce the new fluidized bed grate, new fuel and ash systems and modifications to the air distribution system. BFB conversions are available for boilers up to 300 MWth.

Veolia Energia Łódź S.A., Poland
Pulverized-fired boiler to BFB

  Original Converted
Steam 230 t/h
138 bar
180 t/h
138 bar
Fuels Coal, oil Wood chips, forest residues, agro biomass
Start-up 1975 2011

CFB rebuilds

An existing circulating fluidized bed boiler designed for a single fuel, such as coal, can be rebuilt to widen the fuel portfolio. The boiler can be a multifuel fired boiler with various fuels including coal, or coal can be left out of the fuel mixture completely.

Required modifications to the boiler are always determined case by case, but majority of the refurbishment focus on fuel systems, air staging and ash removal improvements. CFB rebuilds are available for boilers up to 500 MWth.

PT Cikarang Listrindo, Indonesia

  Original Converted
Steam 480t/h
130 bar
130 bar
Fuels Coal Coal, Palm Kernel Shell (20%)
Start-up 2016 2021

CFB Gasifier integrated to an existing boiler

This rebuild solution enables firing both biomass and coal in an existing pulverized coal-fired (PC) boiler. Sourcing adequate quantities of biofuels may be sometimes problematic. In that case, a CFB gasifier produces biofuel-based product gas which can be fired, after integration, in an existing PC boiler. In addition to the new CFB gasifier the existing boiler will be equipped with new product gas burners and related gas and air distribution systems. CFB gasifiers are available up to 300 MWf and they can be integrated to PC boilers up to 600 MWth.

Vaskiluodon Voima, Finland

  Original Converted
Steam 680 t/h (610 t/h)
185 bar (42 bar)
535oC (570oC)
550 MW
680 t/h (610 t/h)
185 bar (42 bar)
535oC (570oC)
550 MW
Fuels Coal Coal, product gas (140 MWf), from harvesting residues, stumps, peat


BFB conversions from:

  • Grate-fired boilers
  • Pulverized coal boilers
  • Recovery boilers
  • Oil-fired boilers


CFB modifications including:

  • Fuel conversions
  • Cyclone modifications
  • Fluidized bed modernizations


Boiler rebuilds in total also including:

  • Single drum conversions
  • Capacity increases
  • Modernizations
How to plan a successful rebuild?

How to plan a successful rebuild?

Rebuilding a power boiler can improve the competitiveness of your business and your processes. But where do you start? Download our e-book to learn how to develop a winning rebuild concept, how to minimize rebuild related risks, and how to ensure smooth ramp up to full production.

Our expertise is at your service

Our expertise is at your service

Our focus is to bring your performance forward. Our expertise in sustainable energy production is at your disposal. Get in touch with our specialists through your local Valmet office, or the link below.

Contact us