Effect of pressure on gasification reactivity of three Chinese coals with different ranks

Chunyu LI, Jiantao ZHAO, Yitian FANG, Yang WANG

PDF(556 KB)
PDF(556 KB)
Front. Chem. Sci. Eng. ›› 2010, Vol. 4 ›› Issue (4) : 385-393. DOI: 10.1007/s11705-010-0501-1
RESEARCH ARTICLE

Effect of pressure on gasification reactivity of three Chinese coals with different ranks

Author information +
History +

Abstract

The gasification reactivities of three kinds of different coal ranks (Huolinhe lignite, Shenmu bituminous coal, and Jincheng anthracite) with CO2 and H2O was carried out on a self-made pressurized fixed-bed reactor at increased pressures (up to 1.0 MPa). The physicochemical characteristics of the chars at various levels of carbon conversion were studied via scanning electron microscopy (SEM), X-ray diffraction (XRD), and BET surface area. Results show that the char gasification reactivity increases with increasing partial pressure. The gasification reaction is controlled by pore diffusion, the rate decreases with increasing total system pressure, and under chemical kinetic control there is no pressure dependence. In general, gasification rates decrease for coals of progressively higher rank. The experimental results could be well described by the shrinking core model for three chars during steam and CO2 gasification. The values of reaction order n with steam were 0.49, 0.46, 0.43, respectively. Meanwhile, the values of reaction order n with CO2 were 0.31, 0.28, 0.26, respectively. With the coal rank increasing, the pressure order m is higher, the activation energies increase slightly with steam, and the activation energy with CO2 increases noticeably. As the carbon conversion increases, the degree of graphitization is enhanced. The surface area of the gasified char increases rapidly with the progress of gasification and peaks at about 40% of char gasification.

Keywords

coal / gasification / pressure / reaction order / shrinking core model

Cite this article

Download citation ▾
Chunyu LI, Jiantao ZHAO, Yitian FANG, Yang WANG. Effect of pressure on gasification reactivity of three Chinese coals with different ranks. Front Chem Eng Chin, 2010, 4(4): 385‒393 https://doi.org/10.1007/s11705-010-0501-1

References

[1]
Kajitani S, Suzuki N, Ashizawa M, Hara S. CO2 gasification rate analysis of coal char in entrained flow coal gasifier. Fuel, 2006, 85(2): 163-169
CrossRef Google scholar
[2]
Huang J J, Fang Y T, Chen H S, Wang Y. Coal gasification characteristic in a pressurized fluidized bed. Energy & Fuels, 2003, 17(6): 1474-1479
CrossRef Google scholar
[3]
Liu G, Tate A G, Bryant G W, Wall T F. Mathematical modeling of coal char reactivity with CO2 at high pressures and temperatures. Fuel, 2000, 79(10): 1145-1154
CrossRef Google scholar
[4]
Kajitani S, Hara S, Matsuda H. Gasification rate analysis of coal char with a pressurized drop tube furnace. Fuel, 2002, 81(5): 539-546
CrossRef Google scholar
[5]
Muhlen H J, van Heek K H, Juntgen H. Influence of pretreatment temperature and pressure on the char reactivity during hydrogasification. Fuel, 1986, 65(4): 591-593
CrossRef Google scholar
[6]
Li S, Xiao X. Influence of pretreatment temperature and pressure on the char reactivity during hydrogasification. Fuel, 1993, 72: 1351-1353
[7]
Li S, Sun R. Kinetic studies of a lignite char pressurized gasification with CO2, H2 and steam. Fuel, 1994, 73(3): 413-416
CrossRef Google scholar
[8]
Bhatia K S, Perlmutter S D. A random pore model for fluid-solid reactions. I. Isothermal kinetic control. American Institute of Chemical Engineers, 1980, 26(3): 379-386
[9]
Liu G S, Niksa S. Coal conversion submodels for design applications at elevated pressures. Part II. Char gasification. Progress in Energy and Combustion Science, 2004, 30(6): 679-717
CrossRef Google scholar
[10]
Li C Y, Zhao J T, Fang Y T, Wang Y. Pressurized fast-pyrolysis characteristics of typical Chinese coals with different ranks. Energy & Fuels, 2009, 23(10): 5099-5105
CrossRef Google scholar
[11]
Zhang L X, Huang J J, Fang Y T, Wang Y. Gasification reactivity and kinetics of typical Chinese anthracite chars with steam and CO2. Energy & Fuels, 2006, 20(3): 1201-1210
CrossRef Google scholar
[12]
Ahn D H, Gibbs B M, Ko K H, Kim J J. Gasification kinetics of an Indonesian subbituminous coal char with CO2 at elevated pressure. Fuel, 2001, 80(11): 1651-1658
CrossRef Google scholar
[13]
Linares-Solano A, Mahajan O P, Walker P Jr. Reactivity of heat-treated coals in steam. Fuel, 1979, 58(5): 327-332
CrossRef Google scholar
[14]
Liu T F, Fang Y T, Wang Y. An experimental investigation into the gasification reactivity of chars prepared at high temperatures. Fuel, 2008, 87(4-5): 460-466
CrossRef Google scholar
[15]
JÜntgen H. Reactivities of carbon to steam and hydrogen and applications to technical gasification processes—A review. Carbon, 1981, 19(3): 167-173
CrossRef Google scholar
[16]
Goyal A, Zabransky R F, Rehmat A. Gasification kinetics of Western Kentucky bituminous coal char. Industrial & Engineering Chemistry Research, 1989, 28(12): 1767-1778
CrossRef Google scholar
[17]
Jones R B, Mccourt C B, Morley C, King K. Maceral and rank influences on the morphology of coal char. Fuel, 1985, 64(10): 1460-1467
CrossRef Google scholar
[18]
Hurt R H, Davis K A, Yang N Y C, Headley T J, Mitchell G D. Residual carbon from pulverized-coal-fired boilers. 2. Morphology and physicochemical properties. Fuel, 1995, 74(9): 1297-1306
CrossRef Google scholar
[19]
Sadhukhan A K, Gupta P, Saha R K. Characterization of porous structure of coal char from a single devolatilized coal particle: Coal combustion in a fluidized bed. Fuel Processing Technology, 2009, 90(5): 692-700
CrossRef Google scholar

Acknowledgments

This work was supported by the Major State Basic Research Development Program of China (973 Program, Grant No. 2006JQJ11131) , the National High-Tech R&D program of China (863 program, No.2008AA050302).

RIGHTS & PERMISSIONS

2014 Higher Education Press and Springer-Verlag Berlin Heidelberg
AI Summary AI Mindmap
PDF(556 KB)

Accesses

Citations

Detail

Sections
Recommended

/