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Research Papers

Coal Coke Gasification in a Windowed Solar Chemical Reactor for Beam-Down Optics

[+] Author and Article Information
Tatsuya Kodama, Nobuyuki Gokon, Shu-ich Enomoto, Shouta Itoh, Tsuyoshi Hatamachi

Department of Chemistry and Chemical Engineering, Faculty of Engineering, and Graduate School of Science and Technology, Niigata University, 8050 Ikarashi 2-nocho, Nish-ku, Niigata 950-2181, Japantkodama@eng.niigata-u.ac.jp

J. Sol. Energy Eng 132(4), 041004 (Sep 01, 2010) (6 pages) doi:10.1115/1.4002081 History: Received October 06, 2008; Revised April 24, 2010; Published September 01, 2010; Online September 01, 2010

Abstract

Solar thermochemical processes, such as solar gasification of coal, require the development of a high temperature solar reactor operating at temperatures above $1000°C$. Direct solar energy absorption by reacting coal particles provides efficient heat transfer directly to the reaction site. In this work, a windowed reactor prototype designed for the beam-down optics was constructed at a laboratory scale and demonstrated for $CO2$ gasification of coal coke using concentrated visible light from a sun-simulator as the source of energy. Peak conversion of light energy to chemical fuel (CO) of 14% was obtained by irradiating a fluidized bed of $500–710 μm$ coal coke size fraction with a power input of about 1 kW and a $CO2$ flow-rate of $6.5 dm3 min−1$ at normal conditions.

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Figures

Figure 1

Scheme of the fluidized-bed reactor

Figure 2

The fluidized-bed reactor and the sun-simulator

Figure 3

Energy flux density of the incident solar-simulated light with three Xe-lamps on the irradiated surface of the bed

Figure 4

Time variation of CO production rate (left column) and coke conversion (right column) for various CO2 flow-rates. The particle-size ranges are (A) 300–500 μm, (B) 500–710 μm, and (C) 710–1000 μm.

Figure 5

Time variation in the light-to-chemical energy conversion (ηchem) for the particle-size range (B) (500–710 μm) at the CO2 flow-rate of 6.5 dm3 min−1

Figure 6

Peak light-to-chemical energy conversion as a function of CO2 flow-rate for the coke particle-size ranges (A) 300–500 μm, (B) 500–710 μm, and (C) 710–1000 μm

Figure 7

Coke bed temperature profiles during irradiation for the particle-size range (B) at the CO2 gas flow of 6.5 dm3 min−1 at normal conditions

Figure 8

Plots of (a) homogeneous model and (b) shrinking-core model for the solar-simulated gasification of coke coal. The particle-size range of coke was 500–710 μm and the CO2 flow-rate was 6.5 dm3 min−1.

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