Walking and talking on and under water /

A collaborative project involving Central Queensland University, the electricity support organization AUSTA Energy, and four Queensland power stations is described. The process that was used in setting up and coordinating, the project is analyzed and discussed. This paper describes the development of Guidelines for the Total Management of Treated Water Systems in Queensland Power Stations by the team. The objective of the project was to minimize corrosion in the stations' Treated Water (TW) circuits by assessing the corrosion inhibitor technologies being used. The challenge faced by the group was not only to choose an inhibitor that was "chemically effective" but, above all, to ensure that it was Workplace Health and Safety, and also environmentally acceptable. The strategy used to obtain and collate the materials needed to write the guidelines is discussed and the outcomes of the project are presented

Bridging the gap : proceedings of the 1998 RACI Chemical Education Division conference held at Central Queensland University, Rockhampton, Queensland, 2-6 July 1998

"The Proceedings of the 1998 National Conference of the Chemical Education Division of the Royal Australian Chemical Institute reflect the central role that chemical education plays in providing and serving as a link to theory and practice, to industry, to the community, and to education at the secondary-tertiary interface. The conference theme, Bridging the Gap, was selected in order to focus on the importance of chemical education in a broad societal context..."--p. i

Effect of temperature on oxide film morphology for steel exposed to 3.5 M sodium hydroxide

Mild steel in contact with sodium hydroxide solutions develops surface films (including a passive oxide layer) that offer good corrosion protection. This is particularly important in the alumina industry where mild steel heat exchanger tubes are in contact with hot Bayer liquor (a mixture of dissolved alumina and sodium hydroxide).There is evidence in the literature that temperature affects the film morphology and that this, in turn, affects the corrosion of the mild steel in contact with the Bayer liquor (Lu, Q., et al, Materials and Corrosion, 51 (2000) p705-711). Such evidence has been limited to studies at only a few discrete temperatures however heat exchanger tubes in refineries are often subjected to a range of temperatures for process reasons. In this paper we report results of a systematic study on the qualitative effect of temperature on heater tube steel morphology for samples exposed to free caustic soda and Bayer liquor. Scanning electron microscopy (SEM) was used to observe changes to the film surface.We have found that the surface of A179 mild steel in 3.5 M NaOH is consistent with duplex oxide layer formation over the temperature range of 100 oC to 220 oC. The surface appears unstable at approximately 140 oC. At 220 oC a small amount of pitting was observed even though the oxide coating appeared compact and uniform. Pitting was not observed for samples exposed to spent Bayer liquor at about the same temperature

A parallel disc device for studying corrosion under intense flow conditions

A novel electrochemical Parallel Disc Device (PDD) has been designed and built at the Process Engineering and Light Metals (PELM) Centre of Central Queensland University. This device, built primarily to study aspects of flow accelerated corrosion, consists of two discs separated by a precision controlled gap. The bottom disc (which accommodates the working electrode) is immobile while the top disc rotates and enables a flow of liquid between the discs. The gap between the discs can be set within the range 0.050 to 5.000 mm with a precision of 0.005 mm. The PDD is capable of generating very high wall shear rates and the shear of liquid at the working electrode is purely tangential as long as flow between the discs remains laminar.This paper presents results of preliminary Computational Fluid Dynamics (CFD) characterisations of the fluid flow in the gap between the parallel discs. In addition we present some results for the electrochemical reduction of dissolved oxygen at a copper PDD electrode

The influence of fly ash morphology and phase distribution on collection in an electrostatic precipitator

Fly Ash is the unburnt portion of fuels which is carried away as solid particles in the hot gas stream of a furnace. About 99% of the fly ash produced in a typical coal-fired power station is removed by electrostatic precipitators or baghouse filters located at the base of the emission stack. Precipitator efficiency is dependent on the charging properties of the fly ash particles and the adhesive forces between them. These forces depend on the size, morphology, chemical constitution and phase distribution of the fly ash. Larger particles are usually found as aggregates held together by bridging material which may be small glassy particles, graphite sheets, or a mixture of amorphous material and small crystallites

The Influence of fly ash morphology and phase distribution on collection in an electrostatic precipitator

Fly Ash is the unburnt portion of fuels which is carried away as solid particles in the hot gas stream of a furnace. About 99% of the fly ash produced in a typical coal-fired power station is removed by electrostatic precipitators or baghouse filters located at the base of the emission stack. Precipitator efficiency is dependent on the charging properties of the fly ash particles and the adhesive forces between them. These forces depend on the size, morphology, chemical constitution and phase distribution of the fly ash. Larger particles are usually found as aggregates held together by bridging material which may be small glassy particles, graphite sheets, or a mixture of amorphous material and small crystallites

A rotating parallel disc device for corrosion studies

This work presents a novel Parallel Disc Device (PDD) to study flow accelerated corrosion (FAC). The device consists of two discs separated by a precision controlled gap. The bottom disc is immobile and accommodates the working electrode and the top disc rotates. The gap between the discs may be set within the range from 50 μm to 5 mm with the precision of ±5 μm. The device has the following features: • it is capable of generating wall shear rates at least as high as 200 000 s-1 at the surface of the working electrode while maintaining laminar flow conditions within the gap; • the shear of liquid at the working electrode is purely tangential; • the value of the wall shear rate may be accurately determined from the geometrical parameters and known rotation speed of the top disc. To experimentally evaluate the performance of the Parallel Disc Device the oxygen corrosion of mild steel was investigated with this device. Results were compared with data obtained with the rotating disc electrode (RDE) and with the rotating cylinder electrode (RCE). Comparisons of data demonstrate that for the same rotation speeds, the PDD can achieve substantially higher wall shear rates. At the same time, the PDD maintained well-defined laminar flow conditions over the entire range of rotation speeds tested. Flow for the RDE and RCE was distinctly turbulent and could be characterised using simple laminar boundary layer equation over a limited range of wall shear rates only (up to 380 s-1)

Electrochemical characterisation of the parallel disk device

A novel Parallel Disc Device (PDD) has been designed and built at the Process Engineering and Light Metals (PELM) Centre of Central Queensland University. The device, built primarily to study aspects of flow accelerated corrosion, consists of two discs separated by a precision controlled gap. The bottom disc (which accommodates the working electrode) is immobile while the top disc rotates. The PDD is capable of generating very high wall shear rates and the shear of liquid at the working electrode is purely tangential as long as flow between the discs remains laminar