High-Temperature Viscometer Test

Because the slag viscosity is the key to a stable dkcharge of molten mineral matter from slagging gasifiers, there are nimierous methods for investigation and prediction. 

The test can be easily repeated with added fluxing agent and the theoretical predictions from the ash composition can be confirmed with such experiments. The main sources of measurement error are [95]  

Composition changes caused by devolatilization (especially for low-rank coal ash) 

Phase separation (crystals, poob of molten iron) 

In general, it should be also noted that comparing the slag produced from coal sample ash in the laboratory usually differs from the real slag formed from the same coal in an industrial gasifier. The main differences can be traced to [84,94]  

---

The Saybolt Eurol viscometer is mostly used in the United States and the testing procedure is described in ASTM D 88 (2013), ASTM D 7496 (2011) (for emulsified asphalts), ASTM E 102 (2009) (for bituminous materials at high temperatures) or AASHTO T 72 (2010). 

If a fully compounded thermosetting rubber is subjected to a plasticity measurement at a high enough temperature and for long enough, it will cure and, consequently, there is not always a clear distinction between a plasticity test and a test for scorch or rate of cure. For example, the Mooney viscometer is used to measure scorch, i.e. the onset of vulcanisation, and an oscillating disc rheometer will measure the plasticity of the compound before the onset of cure as well as the increase in stiffness as curing takes place. 

---