Study of multiphase flow useful to understanding scaleup of coal liquefaction reactors. Technical progress report, September 1-November 30, 1983

Technical Report · Thu Dec 01 04:00:00 EST 1983

OSTI ID:5434472

Knickle, H N

Bubble size and specific interfacial area studies were made in a 33 cm diameter bubble column for the carboxymethyl cellulose (CMC) aqueous solution - air system using a 70 ..mu..m porous plate gas distributor. The bubble column was operated in bubble and Bubble-Slug flow patterns. The Bubble to Bubble-Slug transition occured within superficial gas velocities of 1 to 5 cm/s depending upon the CMC concentration. The transition at higher superficial gas velocity occurred for the most diluted solution. Gas holdup decreased with CMC concentration and exhibited a maximum at the Bubble to Bubble-Slug transition zone. The maximum diminishes with CMC concentration, and appears to vanish for highly concentrated solutions. Results for gas holdup are in fair agreement with those from Schumpe and Deckwer but have large differences for the maximum values. Bubble size was found to be smaller near the column wall and bigger at R/2 and it always increased with superficial gas velocity or CMC concentration. Finding bubble size distributions at high superficial gas velocities and/or highly concentrated CMC solutions was not successful due to some limitations in the photographic equipment. For low and moderate CMC concentrations; it is recommended to work near the bubble to bubble-slug transition where the specific interfacial area exhibits a maximum. This maximum diminishes with increased CMC concentration and eventually vanishes with highly concentrated solutions. The method for evaluation of specific interfacial area taking into account the bimodal distribution found in this study is more accurate than methods using only a mean bubble diameter even if this average is calculated from accurate bubble size distributions as in Buchholz et al.

• Research Organization: Rhode Island Univ., Kingston (USA). Dept. of Chemical Engineering
• DOE Contract Number: FG22-81PC40797
• OSTI ID: 5434472
• Report Number(s): DOE/PC/40797-T2; ON: DE84004226
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
010405* -- Coal
Lignite
& Peat-- Hydrogenation & Liquefaction
BUBBLES
CHEMICAL REACTORS
COAL LIQUEFACTION
FLUID FLOW
FLUID MECHANICS
INTERFACES
LIQUEFACTION
MECHANICS
MULTIPHASE FLOW
RECOMMENDATIONS
SCALING LAWS
SIZE
SURFACE AREA
SURFACE PROPERTIES
THERMOCHEMICAL PROCESSES