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RESEARCH PAPERS

# Multitube Rotary Kiln for the Industrial Solar Production of Lime

[+] Author and Article Information
Anton Meier1

Solar Technology Laboratory, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerlandanton.meier@psi.ch

Enrico Bonaldi, Gian Mario Cella

QualiCal Srl, Via Verdi 3, I-24121 Bergamo, Italy

Wojciech Lipinski

Solar Technology Laboratory, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland Department of Mechanical and Process Engineering, ETH-Swiss Federal Institute of Technology, CH-8092 Zurich, Switzerland

1

Corresponding author.

J. Sol. Energy Eng 127(3), 386-395 (Apr 29, 2005) (10 pages) doi:10.1115/1.1979517 History: Received May 28, 2004; Revised April 29, 2005

## Abstract

We designed and tested a scaleable solar multitube rotary kiln to effect the endothermic calcination reaction $CaCO3→CaO+CO2$ at above $1300K$. The indirect heating $10-kW$ reactor prototype processes $1–5mm$ limestone particles, producing high purity lime of any desired reactivity and with a degree of calcination exceeding 98%. The reactor’s efficiency, defined as the enthalpy of the calcination reaction at ambient temperature $(3184kJkg−1)$ divided by the solar energy input, reached 30%–35% for solar flux inputs of about $2000kWm−2$ and for quicklime production rates up to $4kgh−1$. The use of concentrated solar energy in place of fossil fuels as the source of process heat has the potential of reducing by 20% $CO2$ emissions in a state-of-the-art lime plant and by 40% in a conventional cement plant.

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## Figures

Figure 1

Schematic representation of the indirect heating multi-tube rotary kiln. (Source: PSI.)

Figure 2

Scheme of the experimental setup: (1) heliostat; (2) parabolic dish; (3) feeder; (4) rotary kiln; (5) shutter. (Source: PSI.)

Figure 3

Heat balance scheme

Figure 4

Shutter geometry: opening angle α, lamella width W, and distance D between lamella

Figure 5

Linear approximation of normalized solar power input

Figure 6

Variation of shutter opening angle (left) and solar irradiance (right) during an experiment

Figure 7

Mean solar power input integrated over values calculated at time intervals Δt

Figure 8

Enthalpy diagram for the calcination reaction

Figure 9

Simplified model for heat conduction through cylindrical reactor walls

Figure 10

Reactor efficiency as a function of the CaO production rate for representative solar experiments performed at temperatures in the range of 1200–1400K. Error bars are included for the three experiments presented in Table 1.

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