TBCFB system simulation and optimization for pyrolysis-gasification-combustion of low rank coal

WANG Yaxiong1 YANG Jingxuan1 ZHANG Zhonglin1 MA Xuli1 LI Peng2 HAO Xiaogang1 GUAN Guoqing3

(1.College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan, Shanxi, China 030024)
(2.College of Chemistry and Biological Engineering, Taiyuan University of Science and Technology, Taiyuan, Shanxi, China 030021)
(3.North Japan Research Institute for Sustainable Energy (NJRISE), Hirosaki University, Aomori 030-0813, Japan)

【Abstract】The quality-based utilization technology of low rank coal has attracted much attention due to its advantages in energy saving and emission reduction. A novel triple-bed combined circulating fluidized bed (TBCFB) system, which includes a pyrolyzer, a gasifier and a combustor, is developed to minimize energy loss. A new process is proposed to use char particles instead of sand particles as heat-carried circulating medium and an Aspen Plus process simulation is established to obtain optimum operating conditions for material conversion and energy utilization among three bed reactors. The results show that 40% char combustion can provide enough energy for both low rank coal pyrolysis at 600 °C and gasification of water over 60% residual char at 800.9 °C. The high-heat-capacity char particles significantly reduce the amount of heat-carried particles needed to circulate in the system. To meet the requirements of heat transportation, the mass ratio of char to low rank coal is 5.5, whereas the mass ratios of quartz and ash to low rank coal are 11 and 12, respectively. Comprehensive analysis of syngas composition, cold gas efficiency (CGE) and lower heating value (LHV) indicates that the optimal ratio of steam to char (St/C) is 1.5 in gasification. The simulation results provided some guidance on the industrial application of TBCFB system with char as heat-carried particles.

【Keywords】 quality-based utilization; circulating fluidized bed; simulation; gasification; optimization;


【Funds】 National Natural Science Foundation of China (21506139, U1710101)

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(Translated by CAI TX)


    [1] GAO S T. Consideration of the development of modern coal chemical industry (coal liquefaction) in China [J]. Coal Chemical Industry, 2012, 40 (5): 34–37.

    [2] HE Z, LI R Z. Prediction of China’s energy consumption in the future 20 years [J]. Petroleum & Petrochemical Today, 2016, 24 (9): 1–8 (in Chinese).

    [3] WANG J G, LU X S, YAO J Z, et al. Experimental study of coal topping process in a downer reactor [J]. Industrial & Engineering Chemistry Research, 2005, 44 (3): 463–470.

    [4] ZHANG X F, DONG L, ZHANG J W, et al. Coal pyrolysis in a fluidized bed reactor simulating the process conditions of coal topping in CFB boiler [J]. Journal of Analytical & Applied Pyrolysis, 2011, 91 (1): 241–250.

    [5] XIONG R, DONG L, YU J, et al. Fundamentals of coal topping gasification: characterization of pyrolysis topping in a fluidized bed reactor [J]. Fuel Processing Technology, 2010, 91 (8): 810–817.

    [6] ZHANG J W, WANG Y, DONG L, et al. Decoupling gasification: approach principle and technology justification [J]. Energy & Fuels, 2010, 24 (12): 6223–6232.

    [7] ZHANG Y M, WANG Y, CAI L G, et al. Dual bed pyrolysis gasification of coal: process analysis and pilot test [J]. Fuel, 2013, 112 (112): 624–634

    [8] HAN Z N, ZENG X, YAO C B, et al. Comparison of direct combustion in a circulating fluidized bed system and decoupling combustion in a dual fluidized bed system for distilled spirit lees [J]. Energy & Fuels, 2016, 30 (3): 1693–1700.

    [9] KAJITA M, KIMURA T, NORINAGA K, et al. Catalytic and noncatalytic mechanisms in steam gasification of char from the pyrolysis of biomass [J]. Energy & Fuels, 2009, 24 (1): 108–116.

    [10] FUSHIMI C, WADA T, TSUTSUMI A. Inhibition of steam gasification of biomass char by hydrogen and tar [J]. Biomass Bioenergy, 2011, 35 (1): 179–185.

    [11] BAYARSAIKHAN B, SONOYAM A N, HOSOKAI S, et al. Inhibition of steam gasification of char by volatiles in a fluidized bed under continuous feeding of a brown coal [J]. Fuel, 2006, 85 (3): 340–349.

    [12] TSUTSUMI A, GUAN G Q, FUSHIMI C, et al. Flow behaviors in a high solid flux circulating fluidized bed composed of a riser, a downer and a bubbling fluidized bed [C] //Fluidization XIII: New Paradigm in Fluidization Engineering. Korea, 2010: 407–414.

    [13] GUAN G Q, FUSHIMI C, TSUTSUMI A. Prediction of flow behavior of the riser in a novel high solids flux circulating fluidized bed for steam gasification of coal or biomass [J]. Chemical Engineering Journal, 2010, 164 (1): 221–229.

    [14] FUSHIMI C, GUAN G Q, YU N, et al. Hydrodynamic characteristics of a large-scale triple-bed combined circulating fluidized bed [J]. Powder Technology, 2011, 209 (1): 1–8.

    [15] FUSHIMI C, ISHIZUKA M, GUAN G Q, et al. Hydrodynamic behavior of binary mixture of solids in a triple-bed combined circulating fluidized bed with high mass flux [J]. Advanced Powder Technology, 2014, 25 (25): 379–388.

    [16] YANG J X, MA T B, LIAN W H, et al. Hydrodynamics simulation and feed system pressure analysis of bubbling fluidized bed in TBCFB [J]. Journal of Taiyuan University of Technology, 2017, 48 (1): 18–24 (in Chinese).

    [17] ZHAO Z K, YANG J X, ZHANG W, et al. Hydrodynamic simulation and optimization of the feeding system of a bubbling fluidized-bed gasifier in a triple-bed circulating fluidized bed with high solids flux [J]. Powder Technology, 2017, 321 (321): 336–346.

    [18] HAO X G, WANG J L, LIAN W H, et al. A pyrolysis gasification device and process: 201510160008.9 [P]. 2015-07-22 (in Chinese).

    [19] KUNZE C, SPLIETHOFF H. Modelling of an IGCC plant with carbon capture for 2020 [J]. Fuel Processing Technology, 2010, 91 (8): 934–941.

    [20] WANG J G, WU X S, LIN W G, et al. Total distribution and liquid composition of products from coal topping process in a downer reactor [J]. The Chinese Journal of Process Engineering, 2005, 5 (3): 241–245 (in Chinese).

    [21] WANG Y F. Separation and property analysis of low temperature coal tar components [J]. Journal of Yangtze University (Natural Science Edition), 2012, 9 (5): 26–28 (in Chinese).

    [22] BAI X Y. Basic research on extraction and rectification simulation of crude phenol from low temperature coal tar [D]. Beijing: China Coal Research Institute, 2011 (in Chinese).

    [23] NIKOO M B, MAHINPEY N. Simulation of biomass gasification in fluidized bed reactor using ASPEN PLUS [J]. Biomass & Bioenergy, 2008, 32 (12): 1245–1254.

    [24] ABDELOUAHED L, AUTHIER O, MAUVIEL G, et al. Detailed modeling of biomass gasification in dual fluidized bed reactors under Aspen Plus [J]. Energy & Fuels, 2012, 26 (6): 3840–3855.

    [25] CHEN S H, CAO Z K, SHI J, et al. Steady-state simulation of fixed bed for coal gasification using ASPEN PLUS [J]. Journal of China Coal Society, 2012, 37 (S1): 167–172 (in Chinese).

    [26] LIU B, YANG X M, SONG W L, et al. Process simulation development of coal combustion in a circulating fluidized bed combustor based on Aspen Plus [J]. Energy & Fuels, 2011, 25 (4): 1721–1730.

    [27] WANG J G. Investigation of coal topping process in a downer reactor integrated in circulating fluidized bed combustor [D]. Beijing: Institute of Process Engineering, Chinese Academy of Sciences, 2004 (in Chinese).

    [28] BEHESHTI S M, GHASSEMI H, SHAHSAVAN-MARKADEH R. Process simulation of biomass gasification in a bubbling fluidized bed reactor [J]. Energy Conversion and Management, 2015, 94: 345–352.

    [29] JIN H, LU Y J, LIAO B, et al. Hydrogen production by coal gasification in supercritical water with a fluidized bed reactor [J]. International Journal of Hydrogen Energy, 2010, 35 (13): 7151–7160.

    [30] LU Y J, GUO L J, ZHANG X M, et al. Thermodynamic modeling and analysis of biomass gasification for hydrogen production in supercritical water [J]. Chemical Engineering Journal, 2007, 131 (1): 233–244.

    [31] LU Y J, JIN H, GUO L J, et al. Hydrogen production by biomass gasification in supercritical water in a fluidized bed reactor [J]. International Journal of Hydrogen Energy, 2008;33 (21): 6066–6075.

    [32] HUA Y R, GONG Z J, ZHANG Z Y, et al. Coal partial gasification of ASPEN PLUS simulation based oil fluidized bed [J]. Coal Technology, 2016, 35 (1): 310–311 (in Chinese).

    [33] ZHANG W X. Research on gasification characteristics of pyrolyzed low-rank coal and strengthening the gasification reaction in fluidized bed [D]. Ma’anshan: Anhui University of Technology, 2016 (in Chinese).

    [34] DOHERTY W, REYNOLDS A, KENNEDY D. Aspen Plus simulation of biomass gasification in a steam blown dual fluidized bed [M] //Materials and Processes for Energy. Dublin: Dublin Institute of Technology, 2013: 212–220.

    [35] DUAN W J, YU Q B, WANG K, et al. ASPEN Plus simulation of coal integrated gasification combined blast furnace slag waste heat recovery system [J]. Energy Conversion and Management, 2015, 100 (100): 30–36.

    [36] FENG Y. Gasification reactivity and combustion characteristics of chars from coal pyrolysis [D]. Dalian: Dalian University of Technology, 2016 (in Chinese).

This Article


CN: 11-1946/TQ

Vol 69, No. 08, Pages 3596-3604+3764

August 2018


Article Outline


  • Introduction
  • 1 TBCFB process introduction and model establishment
  • 2 Process establishment and model verification
  • 3 Results and discussion
  • 4 Conclusion
  • Symbol illustration
  • References