Suspension-Firing of Biomass. Part 1: Full-Scale Measurements of Ash Deposit Build-up

Abstract

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Impact of coal fly ash addition on ash transformation and deposition in a full-scale wood suspension-firing boiler

“…Ash deposition probe system 2.3.1. Probe system at Location A An advanced deposit probe system developed in our earlier studies [21][22][23] was adopted in this study. A drawing of the probe system used at Location A of AVV2 is shown in Fig.…”

“…With the deposit mass uptake data, the surface area of the probe exposed to the flue gas and the corresponding exposure time, the ash deposition rate (g/m 2 /h) can be calculated. In this study the derivative based-deposit formation rate (DDF-rate) defined in our earlier work [22,23] is used. The detailed procedure for calculating the DDF-rate is described elsewhere [22].…”

“…To the authors' knowledge, the investigations carried out by Skrifvars et al [29], Jensen et al [50], and Bashir et al [21,22] offer the only full-scale data available on this subject. However, these studies are limited either by the use of a simple deposit probe that cannot quantify the transient deposit formation processes [29,50], or by the lack of a detailed characterization of the formed deposit and fly ash which constraints the mechanistic understanding of deposit formation [21,22]. To resolve these limitations, a systematic study on the transient formation and removal of deposits along with a detailed investigation on ash transformation during pulverized wood combustion are desirable.…”

Modeling of ferric sulfate decomposition and sulfation of potassium chloride during grate‐firing of biomass

“…[10][11][12] One of the major technical challenges associated with the use of biomass in these applications is that the combustion of biomass may result in a considerable amount of alkali chlorides in the flue gas and subsequently lead to severe ashdeposition and corrosion problems in the boilers. 6,7,10,11,[13][14][15][16][17] In order to mitigate the alkali chloride-induced problems in biomass combustion, a feasible method is to use additives to convert the alkali chlorides to less harmful alkali species (such as sulfates or aluminosilicates) and release the chlorine as HCl.…”

“…[10][11][12] One of the major technical challenges associated with the use of biomass in these applications is that the combustion of biomass may result in a considerable amount of alkali chlorides in the flue gas and subsequently lead to severe ashdeposition and corrosion problems in the boilers. 6,7,10,11,[13][14][15][16][17] In order to mitigate the alkali chloride-induced problems in biomass combustion, a feasible method is to use additives to convert the alkali chlorides to less harmful alkali species (such as sulfates or aluminosilicates) and release the chlorine as HCl. 5,9,[18][19][20][21][22][23][24][25][26][27] In biomass combustion, it is desirable to convert the fuel-chlorine to HCl, as it is not condensable on heat transfer surface and the partial pressure of HCl in biomass-derived flue gas is not high enough to cause severe gas-phase corrosion.…”