R&D BLOG

Operational challenges in biomass combustion (EUBIA)

Source: http://www.eubia.org/cms/wiki-biomass/combustion/operational-problems-in-biomass-combustion/

A high combustion quality, in terms of maximal combustion of the burning gases, is very important for a low emission level. It mainly depends on the combustion chamber temperature, the turbulence of the burning gases, residence time and the oxygen excess. These parameters are governed by a series of technical details such as:

  •     combustion technology (e.g. combustion chamber design, process control technology)
  •     settings of the combustion (e.g. primary and secondary air ratio, distribution of the air nozzles)
  •     load condition (full- or part-load)
  •     fuel characteristics (shape, size distribution, moisture content, ash content, ash melting behaviour).

Biomass has a number of characteristics that makes it more difficult to handle and combust than fossil fuels. The low energy density is the main problem in handling and transport of the biomass, while the difficulties in using biomass as fuel relates to its content of inorganic constituents. Some types of biomass used contain significant amounts of chlorine, sulfur and potassium. The salts, KCl and K2SO4, are quite volatile, and the release of these components may lead to heavy deposition on heat transfer surfaces, resulting in reduced heat transfer and enhanced corrosion rates. Severe deposits may interfere with operation and cause unscheduled shutdowns. The release of alkali metals, chlorine and sulfur to the gas-phase may also lead to generation of significant amounts of aerosols (sub-micron particles) along with relatively high emissions of HCl and SO2.

The nature and severity of the operational problems related to biomass depend on the choice of combustion technique. In grate-fired units deposition and corrosion problems are the major concern. In fluidized bed combustion the alkali metals in the biomass may facilitate agglomeration of the bed material, causing serious problems for using this technology for herbaceous based biofuels. Fluidized bed combustors are frequently used for biomass (e.g. wood and waste material), circulating FBC are the preferred choice in larger units. Application of biomass in existing boilers with suspension- firing is considered an attractive alternative to burning biomass in grate-fired boilers. However, also for this technology the considerable chlorine and potassium content in some types of biomass (e.g. straw) may cause problems due to deposit formation, corrosion, and deactivation of catalysts for NO removal (SCR).

Currently wood based biofuels are the only biomasses that can be co-fired with natural gas; the problems of deposition and corrosion prevent the use of herbaceous biomass. However, significant efforts are aimed at co-firing of herbaceous biomass together with coal on existing pulverized coal burners. For some problematic fuels, esp. straw a separate auxiliary boiler may be required. In addition to the concerns about to deposit formation, corrosion, and SCR catalyst deactivation, the addition of biomass in these coal units may impede the utilization of fly ash for cement production. In order to minimize these problems, various fuel pretreatment processes have been considered, including washing the straw with hot water or using a combination of pyrolysis and char treatment.

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Sulfur Recirculation and Improved Material Selection for High Temperature Corrosion Abatement

Babcock & Wilcox Vølund AB in Sweden has installed their Sulfur Recirculation technology in one of the two Waste-to Energy lines at Maabjerg Energy Center (MEC) in Denmarkm in order to combat high temperature corrosion. “Sulfur Recirculation and Improved Material Selection for High Temperature Corrosion Abatement, investigating different aspects of corrosion memory” is a new very interesting report by ENERGIFORSK / KME. Check it out here.

 

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The Biomass Ash Chart – BY BIOFACT: ash content for 500+ biomass fuels

The Biomass Ash Chart – BY BIOFACT is a high quality synthetic plot of the amounts of the Inorganic Fraction for 500+ solid biomass fuels. The fuels are belonging to different classes (20+) such as stem woods, barks, straws and grasses, shells and husks, fruits and residues, animal and industrial wastes. Median values for fossil fuels are included for comparison.

It is useful to expand your overview on the renewable fuels portfolio.


Request us a high quality PDF suitable for A1 printing, email at defusco.biofact@gmail.com!

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UE Electricity from biomass: figures 2019

“Energy production from biomass is a decisive component of the energy transition. Currently, 180 TWh of electricity is produced from biomass in Europe, which means that biomass accounts for 19 % of renewable electricity generation.

Biomass is used as a fuel in thermal power plants or is fermented to produce methane in biogas plants. Biomass power plants perform the same tasks for the stability of the electricity grid as fossil-fired power plants. They are suitable for base load as well as for the supply of balancing and control power. In addition, it is also possible to convert coal-fired power plants to biomass in order to continue using existing sites.

Biogas is usually used in gas engines to generate electricity or can be feeded into the natural gas grid. This contributes a considerable storage potential.

Biomass power plants and biogas plants can be used both in centralized and distributed systems. Biomass, as an all-round renewable energy source, is therefore an indispensable component of future energy supply systems.”


Source text and pictures: VGB report; www.vgb.org/en/data_powergeneration.html?dfid=93253

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New Year, new look. BIOFACT Fuel Dashboard for 2019

Thanks to feedback from users, further development and giving a response to the need of digitization of the reports, with the need of an online accessible dashboard, we are glad to present the new version (5.0) of the BIOFACT tool for the biomass and waste fuels advanced characterization.

Here some snapshots!



We would be very glad to get your feedback!

Best regards,
BIOFACT team

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BIOFACT successfully applied for analysing RDF fuel delivered to two side-by-side boilers

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