Clive Brereton | University of British Columbia (original) (raw)

Papers by Clive Brereton

Circulating Fluidized Beds, 1997

The Minerals, Metals & Materials Series, 2018

Electrolytic salt splitting is a technology where acid and/or base is regenerated from a neutral ... more Electrolytic salt splitting is a technology where acid and/or base is regenerated from a neutral salt using membrane electrolysis. Recent advances in the understanding of brine treatment, membrane stability, and cell design have made electrolytic salt splitting feasible on certain hydrometallurgical solutions. Meanwhile, environmental regulations have made the bulk disposal of salt solutions more difficult. In this paper, sodium sulfate salt splitting is examined from a cost perspective, compared to purchasing the reagents directly. Relative costs are estimated for several regions based on published electricity and reagent prices. The results show that salt splitting is economically favourable in some regions, and can be made more favourable by applying modifications to the traditional three-compartment design.

La presente invention concerne un systeme de stockage d'energie de batterie redox ameliore de... more La presente invention concerne un systeme de stockage d'energie de batterie redox ameliore destine a reduire les niveaux de gaz oxygene et a separer le gaz oxygene du gaz hydrogene, reduisant ainsi la probabilite d'explosions de gaz inflammable. Le systeme comporte au moins une pile, qui comporte un compartiment positif presentant une solution positive, un compartiment negatif presentant une solution negative, et une membrane separant les compartiments positif et negatif. Un reservoir positif est en communication fluidique avec le compartiment positif de la pile, le reservoir positif definissant un espace d'aeration positif pour le gaz positif, qui inclut l'oxygene. Un reservoir negatif est en communication fluidique avec le compartiment negatif de la pile, le reservoir negatif definissant un espace d'aeration negatif. Une conduite de retour est en communication fluidique avec le compartiment negatif et le reservoir negatif pour renvoyer la solution negative de l...

Chemical Engineering Research Design, 1992

Pressure fluctuation data have often been utilized to infer hydrodynamic regime transitions in ga... more Pressure fluctuation data have often been utilized to infer hydrodynamic regime transitions in gas fluidized beds, but there have been wide variations in how the measurements have been carried out and interpreted. It is shown that careful pressure fluctuation measurements, in which limitations of previous studies are avoided, do show changes in the hydrodynamic character between different regimes. For the system studied, sand particles of mean diameter 148 μm fluidized by ambient air in a column of diameter 152 mm, the turbulent regime corresponded to a region of intermittency between bursts of slug-like behaviour and bursts of fast-fluidization-like motion, the latter becoming dominant as the gas velocity was increased. Care is required in interpreting pressure fluctuations in terms of hydrodynamic behaviour if regimes are to be correctly inferred

Circulating Fluidized Bed Technology, 1986

ABSTRACT This paper will look at the two aspects of the fluid mechanics of circulating beds: macr... more ABSTRACT This paper will look at the two aspects of the fluid mechanics of circulating beds: macroscopic density profiles in small and large units; and the micro-structure of the flow. The first part of the paper reiterates the work of Stromberg (1980, 1981) expanding upon various aspects which have not been treated previously. The second part of the paper presents some results from capacitance studies which lend some insight into bed operation at low solids loadings.

Powder Technology, 2016

Abstract A technique using the measurement of gas phase concentrations for the study of mass tran... more Abstract A technique using the measurement of gas phase concentrations for the study of mass transfer in gas–solid fluidized beds has been developed. This method uses thermal conductivity detectors (TCDs) to measure local concentrations of a gaseous species as it evolves from a continuously sprayed binary liquid into the system. The binary liquid, a mixture of paraffin wax and n -heptane, was chosen to be a low temperature analogue of bitumen, which is thermally converted into lighter liquid products using the FLUID COKING™ process. In both the commercialized process and the low temperature analogue, the volatile fraction of the liquid feed is released into the gas phase, while the heavy components remain in the bed and eventually solidify. The n -heptane vapor concentration was continuously measured using three TCDs, sampling from different locations in a 4-m tall, 0.4 m × 0.1 m fluidization column. By varying operating conditions such as the superficial gas velocity, bed temperature, and air-to-liquid ratio, the present work successfully demonstrated the ability to measure changes in mass transfer conditions in a fluidized bed continuously and accurately with fast response.

Separation and Purification Technology, 1997

Experimental filtration tests were carried out in a hot gas filtration facility with two differen... more Experimental filtration tests were carried out in a hot gas filtration facility with two different dusts (coal ash and gasifier char) using high-temperature fabric filters made from Nextel@ 3 12 ceiamic fibers. The filtration efficiency and conditioning behaviour of these filters were investigated for a variety of operating conditions, including face velocity, solids loading, temperature, pulse duration and maximum pressure-drop setting under both reducing and oxidizing conditions simulating gasification and combustion, respectively. Significant differences in the conditioning behaviour of the fabric filter were observed with the two types of dust. Pressure-drop variations as a function of time were investigated for a variety of conditions. A drastic decrease in the pulse interval and a linear increase in the baseline pressure drop were observed when the face velocity was increased. The test results showed that the filtration efficiency was primarily affected by the face velocity. The filter bags demonstrated high filtration efficiencies (i.e. 99.95-99.99%) for a face velocity in the range of 12-24 mm s-l. At a face velocity of 40 mm s-' the filtration efficiency was reduced to 99.5%.

Sadhana, 1987

The circulating fluidized bed reactor has unique qualities which differentiate it from other gas-... more The circulating fluidized bed reactor has unique qualities which differentiate it from other gas-solid contactors and make it promising for a wide range of reaction~,. A 0-15 m x 0.15 m x 7.3 m tall circulating bed reactor with solids returned via an L-val" e has been established at the University of British Columbia for combustion of a wide range of solid and heavy liquid fuels. The reactor is heavily instrumented to allow reaction characteristics to be related to reactor hydrodynamics and transfer processes. Novel features are incorporated to permit measurement of solids circulation rates and in the configuration of secondary gas entry ports. Preliminary heat transfer data, temperature profiles and pressure profile~ are reported for operation at high temperatures.

Powder Technology, 1990

The behavlour of sllaca aerogel powder and iron oxide-slhca aerogel powder m fluldlzed beds has b... more The behavlour of sllaca aerogel powder and iron oxide-slhca aerogel powder m fluldlzed beds has been observed at gas velocrtles between 0 1 and 1 6 m/s to determine whether aerogels can be treated m turbulent and cwculatmg fluzdzzed bed (CFB) contactors Pure slhca aerogel particles agglomerate at these velocltles to create larger particles whose equwalent diameter 1s a strong function of the gas velocity at which they are formed Although they retain the high specific surface area of the original powder, the agglomerates have a low permeability. It was never possible to smoothly circulate pure slllca aerogel m a CFB unit with an L-valve, because the fine material could not be returned to the base of the riser, and large agglomerates remained suspended in the riser However, by adding a granular dlluent, it was possible both to suppress much of the agglomeration and to form a mixture ldeal for CFB contacting Iron oxide-slhca agglomerates were homogeneous m size and msensltwe to the gas velocity. Tests m a small CFB unit wrth a V-valve showed that iron oxide-silica aerogel particles could be circulated smoothly and steadily, because fluldazed aerogel particles m the V-valve leg reorganazed themselves m to agglomerates which behaved like Geldart's Group A or B powders. respect to the solvent. The fme porous structure of the gel is thus preserved and a very light powder, with a bulk density of the order of 100 kg/m3 or less and particle diameter less than 20 pm, 1s produced.

International Journal of Heat and Mass Transfer, 1995

Measurements of local solids concentration, heat transfer and erosion were obtained in a 152 mm d... more Measurements of local solids concentration, heat transfer and erosion were obtained in a 152 mm diameter x 9.3 m tall circulating fluidized bed operated at room temperature with 200 /zm sand particles al: a superficial gas velocity of 7.0 m s-l with different solids circulation rates. Local solids concentrations were found to be higher in the fin region than on the crests of membrane tubes. For the small heat transfer surfaces investigated, this led to higher local heat transfer coefficients in the fin region, a trend which is the reverse of that for long heat transfer surfaces. Erosion rates were higher on the tube crests than on the fins.

Industrial & Engineering Chemistry Research, 1999

Experiments were carried out in a pilot-scale test rig at temperatures of 600--770 C to investiga... more Experiments were carried out in a pilot-scale test rig at temperatures of 600--770 C to investigate the potential of filter cakes formed in hot gas filtration to remove sulfur dioxide, nitric oxide, and alkalis. The results demonstrate that a filter cake of fly ash particles is capable of contributing to SOâ capture, particularly with injection of a fresh sorbent. A