A quenching apparatus for the gaseous products of the solar thermal dissociation of ZnO

  • D. Gstoehl
  • A. Brambilla
  • L. O. Schunk
  • A. Steinfeld
Reactivity of Solids

Abstract

Rapid cooling for avoiding the recombination of Zn vapor and O2 derived from the solar thermal dissociation of ZnO is investigated using a thermogravimeter coupled to a quenching apparatus. The ZnO sample, which is placed in a cavity receiver and directly exposed to concentrated solar irradiation, underwent dissociation in the temperature range 1,820–2,050 K at a rate monitored by on-line thermogravimetry. The product gases were quenched by water-cooled surfaces and by injection of cold Ar at cooling rates from 20,000 to 120,000 K/s, suppressing the formation of ZnO in the gas phase and at the walls. Zinc content of the collected particles downstream varied in the range 40–94% for Ar/Zn(g) dilutions of 170 to 1,500.

Nomenclature

b.p.

Boiling point

CR

Cooling rate, K/s

D

Dilution (nAr/nZn)

di

Injector diameter, mm

LHZ

Length of quench device inlet, mm

Ln

Liters under standard conditions at 273.15 K and 1 atm

m.p.

Melting point

\( \dot{m}_{ZnO} \)

ZnO dissociation rate, mg/s

n

Number of atoms, mol

\( \dot{n} \)

Molar flow rate, mol/s

p

Partial pressure, Pa

T

Temperature, K

Xparticles

Zinc yield based on collected particles

Yinstantaneous

Zinc yield based on oxygen balance

z

Distance from quench device inlet, mm

Subscripts

AF

Annular flow

sat.

Saturation

CZ

Cold zone of quench device

dec.

Decomposition

HZ

Hot zone of quench device

QF

Quench flow

RF

Reacting flow

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Copyright information

© Springer Science+Business Media, LLC 2008

Authors and Affiliations

  • D. Gstoehl
    • 1
  • A. Brambilla
    • 1
  • L. O. Schunk
    • 1
  • A. Steinfeld
    • 1
    • 2
  1. 1.Solar Technology LaboratoryPaul Scherrer InstituteVilligenSwitzerland
  2. 2.Department of Mechanical and Process EngineeringETH ZurichZurichSwitzerland

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