Agro biomass covers boilers able to combust difficult biomasses as cereal straw, rice straw, miscanthus, corn stover, palm leaves, olive residues, top and trash from sugar cane etc.
Design also allows for supplementary firing of wood chips up to 50% heat input.
BWE boilers are world-leading for 15-50 MWe in the agricultural waste segment.
Agro biomass boilers can be designed with reheat cycles ranging from 30 MWth to 165 MWth, depending on fuel properties.
High alkaline fuel -> low ash melting point.
Boilers are designed with high steam parameters up to 110 bar and 540 °C.
The boilers are bottom supported, drum type, three pass.
Combustion takes place on a water-cooled vibration grate.
Input: 130 MWth
Output: 44.2 MWe
Fuel: Straw and up to 50% wood chips
Firing system: Grate
Integrated flue gas treatment
Input: 49.95 MWth
Output: 11.6 MWe
Fuel: Straw
Firing system: Grate
Input: 110 MWth
Output: 34.3MWe + 78.5 MWheat
Fuel: Straw and up to 50% wood chips
Firing system: Grate
Integrated flue gas treatment and condensing
Forest biomass boilers operate on pure wood biomass or similar biomasses such as wood chips, wood pellets, bark, PKS etc.
Plant size target ranges between 15-50 MWe or 50-150 MWth.
Forest biomass boiler can be designed with reheat cycle from 75 MWth and upwards, typically with 140 bar, HP and RH temperature of 540 °C.
High moisture fuel 35-55%.
Boilers are designed as two or three pass boilers depending on fuel properties.
Combustion takes place on a water-cooled vibration, with primary air heating up to 300 °C.
Depending on the fuel moisture content, feeding is done either via spreaders or by single screw stokers.
Input 75 MWth
Output: 27.8 MWe + 6 MWheat
Design: Reheat
Fuel: Virgin/waste wood
Firing system: Grate
Input 75 MWth
Output: 27.8 MWe + 6 MWheat
Design: Reheat
Fuel: Virgin and clean recycled wood
Firing system: Gate
Input: 240 MWth
Output: 89 MWe
Fuel: Virgin wood
Boiler type: Drum
Firing system: Grate and PF
Waste wood is difficult to manage and boilers must comply with the EU waste incineration directive, thus require a high level of skilled know-how which BWE has entirely inhouse.
A typical design is 80 MWth. However, waste wood boiler technology covers the range from 30-160 MWth.
Steam parameters are reduced typically to 70 bar 470 °C and the grate is modified to have corrosion and heat resistant cast elements.
BWE waste wood boilers are designed with flue gas recirculation (FGR).
Furnace, ceiling and 2nd pass membrane walls with Inconel lining.
Input: 55 MWth
Fuel: Waste wood
Steam: 100 bar, 540 °C
Design: 2 pass
Input: 76 MWth
Fuel: Waste wood
Steam: 75 bar, 470 °C
Design: 3 pass
BWE provides boiler solutions for pulverised biomass/fuel (PF) as well as conversions of existing fossil fuelled plants to biomass. BWE designs once through boilers with USC steam parameters.
Through several projects and CFD calculations, BWE’s own pulverised biomass burner has been optimised for stable and efficient low NOx combustion.
The technology includes PC combustion system and design of large-scale utility boilers.
Pulverised biomass boilers are made as steam boilers or as heat only boilers (HOB). A typical HOB design is 80-140 MWth.
Hammer mills or vertical roller mills.
Pulverised biomass burners (front, opposed or tangential).
Combustion air heating via rotating APH.
Biomass dust fired boiler
Input: 350 MWth
Output: 80 MWe and district heating
Conversion from peat to wood pellets
Input: 132 MWth
Design: Heat only boiler
Designed for oil, natural gas and wood pellets
Originally built by BWE for gas firing with steam conditions of 600ºC and 300 bar
Input: 800 MWth
Output: 360 MWe
The water cooled vibrating grate developed for biomass combustion can be applied for a fuel input up to 150 MWth. Generating steam with data as high as 140 bar and 540°C, an elevated plant efficiency is ensured.
The water cooled vibration grate represents BAT for straw combustion and provides a reliable operation with minimum of maintenance. The BWE Boiler is carefully designed with three passes, slagging super heaters, large super heater pitch and tubes in austenitic material grade.
The water cooled grate is designed as a membrane wall with air nozzles in the fins. The primary air in the range of 30% of the total air is distributed based on a predesigned and optimized hole pattern in the grate surface. The main combustion air is introduced through a number of air injection nozzles above the grate in connection to the furnace noses.
The straw feeding system and patented scarifier developed is adaptable to different types of square bales such as Heston and CLAAS. The straw bales are conveyed through two, three or four sets of straw feeding lines to the boiler. The BWE Boilers are designed and optimized for operation with corrosive and sticky ash caused by cereal straw combustion.
Hence super heaters are designed as slagging super heaters using austenitic material grade.
BWE Boilers are found in biomass power plants in Sweden, the UK, Germany, China, India as well as Denmark.
On a straw-fired boiler it is possible to co-fire with other biomass fuels such as wood-chips, other agro-biomass, cotton stalkes, wood chips/pellets up to 50%wt/wt-%.
The BWE Boilers for biomass is of the drum type with natural circulation, it can be delivered in thermal sizes ranging from 40 to 130 MWth and at steam data up to 140 bar, 540°C. They are all bottom supported and include vibration grates that are water cooled and part of the evaporator high pressure system.
Electric size is normally in the range of 10 to 45MWe.
The integrated and optimized Flue Gas Treatment (FGT) supplied with BWE boilers includes the specification of dry sorbent injection, FF and SCR. The design allows the DSI and SCR to operate at sufficient temperature without any interference with the steam cycle and it allows meeting ELV even during plant disturbances.
The FGT solution can be extended with Flue Gas Condenser, Heat Exchanger and Combustion Air Humidifier for combined heat and power (CHP) optimisation. This FGT extension allows flue gas exit temperatures below 40°C and fuel utilisation above 100% with an increase of 20% of the heat supplied to the district heating network.
The standard grate-fired BWE Boilers are offered in the sizes of 40, 80 and 130 MJ/s. By modifying the design it can be tailor- made and adapted to customer requirement and optimized for the specific fuel, as straw or other higher density biomass fuels like wood chips. One type for straw feeding the grate through stokers and another type for higher density biomass fuels like wood chips using air-swept spreaders.
By straw firing, the bales are conveyed through seal gate arrangements to the scarifiers where the bale is loosened before it is pressed through the water cooled ducts to the grate.
By wood chips firing, the fuel is blown into the furnace and onto the grate by air-swept spreaders.
As a compact and efficient alternative the 2 pass boiler with reheat is highly suited for wood chips.
BWE Biomass Boilers (BWE) meets the market demand through development, design, construction and commissioning of high efficiency advanced utility and biomass steam boilers to the energy industry. Based on 30+ years of experience in biomass, the boilers represent the best-available-technology (BAT) in the market through proprietary designs, which include own boiler, grate and fuel feeding technology as well as deep knowledge of flue gas technology . The Business has a particular strong track-record and solution offering for utility companies, independent power producers (IPP) and industrial customers, primarily targeting the segment ranging from 50-160 MWth. Market-leading position within agricultural biomass, where BWE sees significant market potential, particularly in developing markets. The organisation comprises highly dedicated and skilled engineers based in Copenhagen, Denmark and Noida, New Delhi and India.
Biomass is more complex and different in composition than anyone might expect. The fuel brings it all which in particular is true, when firing annual crops with a chemical composition more complex and aggressive than wood and wood like fuels. This saying applies in particular when firing biomass in a modern boiler with high steam parameters.
The chemical complexion in crops, typically generate very low ash melting temperatures and highly corrosive components. This aspect influences the BWE Boiler biomass design in unique ways in terms of physical design, cleaning technology and material selection.
The design and material selection has evolved over decades of experience and has today reached a level of excellence, in which long duration and economical and reliable operation can be expected.
Challenged on biomass fuels since the 1980’s, when focus was on straw, we today masters BAT in the efficient combustion of the most diversified biomass fuels.