10 research outputs found
Danish Experiences with Deposit Probe Measurements in Grate and Pulverized Fuel Biomass Power Boilers
Quantification of Ash Deposit Build-up and Removal in a Straw and Wood Suspension-Fired Boiler
Characterization and Quantification of Deposits Buildup and Removal in Biomass Suspension-Fired Boilers
Propensity of Lignin to Associate: Light Scattering Photometry Study with Native Lignins
Suppression of CCR impacts metabolite profile and cell wall composition in Pinus radiata tracheary elements
Deposit Probe Measurements in Large Biomass-Fired Grate Boilers and Pulverized-Fuel Boilers
A number of full-scale
deposit probe measuring campaigns conducted
in grate-fired and suspension-fired boilers, fired with biomass, have
been reviewed and compared. The influence of operational parameters
on the chemistry of ash and deposits, on deposit build-up rates, and
on shedding behavior has been examined. The firing technology and
the fuel utilized influence the fly ash and deposit chemical composition.
In grate-firing, K, Cl, and S are enriched in the fly ash compared
to the fuel ash, while the fly ash in suspension-firing is relatively
similar to the fuel ash. The chemical composition of the deposits
formed is determined by the fly ash composition and the flue gas temperature;
increases in the local flue gas temperature lead to higher contents
of Si and Ca and lower contents of Cl in the deposits. The net deposit
build-up rates in grate-fired and suspension-fired boilers are at
similar levels, 0â100 g/m<sup>2</sup>·h, while the ash
deposit propensity is an order of magnitude larger in grate fired
boilers than in suspension-fired boilers. Deposit build-up rates were
found to increase at flue gas temperatures close to the melting temperatures
of the fly ash. Furthermore, the rate of deposit build-up increased
with the K-content of the fuel ash and fly ash for grate-fired boilers.
For suspension-fired boilers, deposition rates are comparatively low
for wood-firing and increase with increasing fuel straw shares. Shedding
of deposits occurs by melting during straw-firing on a grate at high
flue gas temperatures (>900 °C). At lower flue gas temperatures,
the deposits can be removed by soot blowing. The required soot blower
impact pressure is strongly influenced by the surface temperature,
such that a high surface temperature makes the deposit more difficult
to remove. During straw/wood-firing in suspension-fired boilers, shedding
occurred by debonding with incomplete removal at flue gas temperatures
of 600â1000 °C and by debonding with complete removal
during wood-firing in suspension-fired boilers at high flue gas temperatures
(1300 °C). Shedding events were not observed during wood suspension-firing
at low flue gas temperatures (<900 °C). Here, a steady-state
mass of deposits on the probe was observed. Increased exposure times
and probe temperatures lead to deposits that are difficult to remove.
This was observed for grate-firing of straw and for straw/wood firing
in suspension-fired boilers