ISO 21404:2020 pdf download

ISO 21404:2020 pdf download.Solid biofuels — Determination of ash melting behaviour
1 Scope
This document specifies a method for the determination of the characteristic temperatures for the ash melting behaviour of solid biofuels.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 16559, Solid biofuels — Terminology, definitions and descriptions
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 16559 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at http:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1 shrinkage starting temperature
SST
temperature is defined as when the area of the test piece falls below 95 % of the original test piece area at 550 °C (or other ashing temperature used) due to shrinking of the test piece
Note 1 to entry: Shrinkage may be due to liberation of carbon dioxide and volatile alkali compounds. It may also be due to sintering and may be a first sign of partial melting.
3.2 deformation temperature
DT
temperature at which the first signs of melting occur
Note 1 to entry: It is common that DT will occur shortly before HT/FT. If the test results show a small temperature difference between SST and DT and a large temperature gap between DT and HT/FT it is advised that the analyst review the images to verify if the temperature recorded as DT is truly due to melting or if it is a shape change caused by excessive shrinkage.
Note 2 to entry: Deformation temperature can be seen as rounding of the edges, smoothing of surfaces, expansion of the cylinder or general changing of the cylinder shape. If the test piece starts to swell or bubble without the edges being rounded, the temperature is registered as DT (since swelling and bubbling only occur when a fraction of the ash is melted).
Note 3 to entry: For computerized evaluation a shape factor change can be used to define the deformation temperature. For definition of shape factor see Annex A.
3.3 hemisphere temperature
HT
temperature at which the test piece forms approximately a hemisphere i.e. when the height is half of the base diameter
3.4 flow temperature
FT
temperature at which the ash is spread out over the supporting tile in a layer, the height of which is half of the height of the test piece at the hemisphere temperature as depicted in Figure 1.
Note 1 to entry: Half of the height of the test piece at the hemisphere temperature has been defined due to frequently occurring bubbling effects. This is especially important for automatic image evaluation.