ISO 540:2008 pdf free.Hard coal and coke — Determination of ash fusibility.
ISO 540 specifies a method of determining the characteristic fusion temperatures of ash from coal and coke.
The method for determination of the fusibility temperatures of coal ash and coke ash described in this International Standard provides information about the fusion and melting behaviour of the composite inorganic constituents of the ash at high temperatures. The standard method is based on the “Seger Cone” method, which is well known in the ceramic industry, the use of which predates the year 1900. The conditions of the test, as well as basic studies on the influence of ash chemistry and of gas composition on ash fusibility temperatures (which have led to the standardization of the method), arose from the pioneering work of Fieldner, Hall and Field L1.
In the laboratory, the ash used for the test is a homogeneous mixture prepared from a representative sample of the coal or coke, and the determination is performed at a controlled rate of heating in either a reducing or an oxidizing atmosphere. In contrast, under industrial conditions, the complex processes of combustion and fusion involve heterogeneous mixtures of particles, heating rates (that can be several orders of magnitude greater than those used in the standard test) and variable gas composition.
During the first quarter of the 20th century, laboratory, pilot-scale and field studies were undertaken to establish that the ash fusibility test can provide a reasonable indication of the propensity of ash to form fused deposits (referred to as “clinker”) in stoker and other fuel-bed type furnaces (Nicholls and Selvig [2]). Subsequently, the test has been used as a general indicator of the tendency for ash to fuse on heating and of ash slagging propensity in pulverized coal-fired furnaces.
4 Principle
A test piece made from the ash is heated under standard conditions and continuously observed. The temperatures at which characteristic changes of shape occur are recorded. The characteristic temperatures are defined in Clause 3. (See also Figures 2, 3 and 4.)
Although the determination is usually performed in a reducing atmosphere, additional information can sometimes be obtained by performing a further determination in an oxidizing atmosphere. In general, the reducing atmosphere in 7.1 gives the lowest characteristic temperatures.ISO 540:2008 pdf download.