Heat transfer in fixed beds at very low (<4) tube-to-particle diameter ratio

Journal Article · Fri Aug 01 04:00:00 EDT 1997 · Industrial and Engineering Chemistry Research

DOI:https://doi.org/10.1021/ie9605950· OSTI ID:536413

Dixon, A G ^[1]

---

1. Worcester Polytechnic Inst., MA (United States). Dept. of Chemical Engineering

Fixed bed reactor tubes are often used in applications in which the need for the removal of heat from highly-exothermic chemical reactions (e.g., ethylene epoxidation to ethylene oxide) or the supply of heat to highly endothermic reactions (e.g., the steam reforming of methane to syngas) constrains the tube diameter to be small, but the need for high gas velocities and reasonable pressure drops constrains the particle diameter to be fairly large. New heat transfer measurements are reported for packings of full and hollow cylinders in tubes over a tube-to-particle diameter ratio (N) range of 1.8--5.6. Both high and low thermal conductivity packings were used. These results are analyzed in conjunction with previously-reported data for spheres in the range 1.13 < N < 6.4 and data for cylinders and rings in the range 5.2 < N < 6.9 to provide a comprehensive picture of heat transfer in the region of very low N (<4) and a comparison to data at higher N. Single-phase heat transfer correlations are critically evaluated with regard to their dependence on N, to determine whether their range of applicability extends to N < 4. The effective radial thermal conductivity k{sub r} and wall heat transfer coefficient h{sub W} depend on N less strongly for full and hollow cylinders than they do for spheres. For spheres, there is evidence of high rates of radial heat transfer as N approaches unity, and the bed behaves as a single pellet string, but for 2 {le} N {le} 4, k{sub r} is highly dependent on the specific value of N.

• OSTI ID: 536413
• Journal Information: Industrial and Engineering Chemistry Research, Journal Name: Industrial and Engineering Chemistry Research Journal Issue: 8 Vol. 36; ISSN IECRED; ISSN 0888-5885
• Country of Publication: United States
• Language: English

Related Subjects

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
CHEMICAL REACTORS
HEAT TRANSFER
METHANE
PACKED BEDS
PARTICLE SIZE
SHAPE
STEAM REFORMER PROCESSES
THERMAL CONDUCTIVITY
TUBES