Stability of COM in Large Storage Tanks

Abstract

The result of a large scale COM stability test and, some new points and techniques of practical use will be discussed in this paper.
That is, a sample of 2 tons of COM was prepared and stored in a test tank (10m height, 0.5m inner diameter, 70°C storage condition) for a period of one month and a stability test was conducted.
As a result it was shown that COM without additive was unstable as same as in the case of small cylinder test, exhibiting a settling of coal particles after four days and showing a viscosity of more than 15, 000 cp at the bottom of tank (70°C), making it difficult to be pumped up, while COM with addition of 0. 125% of multi-branched high molecular nonionic surface active agent developed by authors would maintain it stable over a period of one month at 70°C, when COM is prepared such that its viscosity is in the order of several thousands and no coarse particles are found in the COM.
The fact that COM needs to be controlled as for its viscosity and particle size (degree of pulverization) is a new discovery, since detailed examination was impossible at the bottom of a small cylinder.
Finally, it was confirmed that multi-branched high molecular nonionic surface active agents would keep a wide variety of COM stable regardless of the types of coals and oils over a period of one month storage at 70°C in a large storage tank, when the above conditions were met.