Electrokinetically enhanced flow and dewatering characteristics of concentrated black coal-water suspensions in pipes
- Royal Melbourne Inst. of Technology, Victoria (Australia)
The transportability and dewatering of coal-water mixtures flowing in a pipe may be enhanced by the application of electrokinetic techniques. Previous experimental work by other workers shows a significant reduction in the wall shear stress, and consequently a decrease in pumping energy requirements for the flow of coal-water mixtures in pipes combined with electrodewatering. In this process the pipe wall acts as the cathode and a centrally aligned tube as the anode. The effects of {open_quote}In-pipe electrodewatering{close_quote} on the flow properties and stability of concentrated coal-water mixtures flowing in various alternative anode-cathode arrangements are presented in this paper. The application of an electrical energy flux at the electrode surface (< 6.1 kW/m{sup 2}) in a dewatering section of pipe (L{sub e}=1m) effectively reduces the pumping energy requirements by as much as one order of magnitude. The stability of flow conditions is investigated in a concentric anode-cathode pipe arrangement consisting of a dewatering and a non-dewatering section (L{sub o}). In this system (L{sub o}/L{sub e}) < 4.0. A microscopic study of dilute coal-water suspensions in the presence of a DC electric field revealed the migration of coal particles towards the anode and the structural formation of coal particle chains. The electrorheological behaviour of concentrated coal-water suspensions is examined with the use of a modified coaxial rheometer. The coal fines (d{sub 50}=17.7{mu}m) used in all experiments were produced by milling a low rank bituminous black coal which was followed by a sieving process that eliminated coal particles that were greater than 75{mu}m in size.
- OSTI ID:
- 490311
- Report Number(s):
- CONF-970310-; TRN: 97:003021-0029
- Resource Relation:
- Conference: 22. international technical conference on coal utilization and fuel systems, Clearwater, FL (United States), 17-20 Mar 1997; Other Information: PBD: [1997]; Related Information: Is Part Of The proceedings of the 22nd international technical conference on coal utilization and fuel systems; Sakkestad, B.A. [ed.]; PB: 1012 p.
- Country of Publication:
- United States
- Language:
- English
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