Improvements in the Rheological Characteristics of the Complex Coal-Water Suspension Using Gasification Derived Waste Water

Abstract

The area of application of coal as a source of energy is expanding to sophisticated devices such as internal combustion engines, liquid fuel-based furnaces, gasification, pyrolysis, etc. The coal reserves in the developing countries are mainly young and of low rank, which have poor slurrying and rheological characteristics. The present research presents a novel methodology to improve the slurrying and rheological characteristics of the coal water suspension using the gasification derived waste water. The gas produced by a gasifier contains a lot of tars, which are washed down along with the sprayed water; this water is known as gasification derived waste water. In the present case, the waste water is collected from the gas cleaning unit of a 10 kg/h downdraft biomass gasifier. This waste water contains some amount of dissolved tars. When this water is used for the preparation of the coal water suspension, an improvement in the slurrying and rheological characteristics of the suspension is observed. The tars are observed to the choke the pores on surface of the coal particles; this checks the flow of water into the pores. So, the maximum amount of water remains in the particle’s surroundings, thereby reducing the particle to particle interaction and hence the viscosity by ∼41-55%. This study thus provides a base and a novel method to utilize the waste water, which otherwise is of no use and quite harmful.