Fluidized Bed Steam Gasification of Solid Biomass - Performance Characteristics of an 8 MWth Combined Heat and Power Plant

The work focuses on a dual fluidized bed gasification technology that is successfully operated for combined heat and power production at a scale of 8 MWth in Guessing/Austria since 2002. The reactor concept consists of a circulating fluidized bed system with a steam-fluidized bubbling bed integrated into the solids return loop. Accompanying the operation of the commercial scale plant, parameter models have been developed and validated by comparison to measured data. As the models naturally fulfill mass and energy balances, the simulation also allows the validation of measurement data. The behaviour of the plant is studied by carrying out variations of selected parameters. Evaluation of different plant operation cases yields correlations between process variables. The solids circulation rate is shown versus riser exit velocity. Fuel water content and gasification temperature significantly influence global plant performance. Simulation predicts the efficiency of the existing power plant in optimized operation. Finally, part load behaviour is investigated and performance maps of the CHP plant are presented. High fuel water content at high gas engine load results in high gas velocities in the riser (erosion limit) and higher heat ratio in the produced energy. It is concluded that CHP-concepts based on fluidized bed steam gasification can reach high electric efficiencies and high overall fuel utilization rates even at small plant capacities of about 10 MWth.

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Fluid-Dynamic Investigations in a Scaled Cold Model for a Dual Fluidized Bed Biomass Steam Gasification Process: Solid Flux Measurements and Optimization of the Cyclone

International Journal of Chemical Reactor Engineering ◽

10.2202/1542-6580.1394 ◽

2007 ◽

Vol 5 (1) ◽

Cited By ~ 9

Author(s):

Andreas Kreuzeder ◽

Christoph Pfeifer ◽

Hermann Hofbauer

Keyword(s):

Fluidized Bed ◽

Circulating Fluidized Bed ◽

Separation Efficiency ◽

Fluid Dynamic ◽

Steam Gasification ◽

Circulation Rate ◽

Cold Model ◽

Gasification Process ◽

Dual Fluidized Bed ◽

Bed Material

Gasification of biomass is an attractive technology for combined heat and power (CHP) production. A dual fluidized bed steam gasifier is in commercial operation at the biomass CHP plant in Guessing/Austria since 2002. For circulating fluidized bed applications the bed material consumption is economically crucial. Thus, cyclones for circulating fluidized beds need to be designed properly. Some erosion and caking in the cyclone of the gasifier could be observed with increasing hours of operation. The influences of these effects as well as the influence of the solid circulation rate between the two units on the separation efficiency were investigated by fluid-dynamic investigations using a scaled cold model. The results show that due to erosion and caking elutriation rates are increased, especially for smaller particles. However, the cyclone achieves fractional separation efficiencies of more than 99.9%.

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Estimation of solids circulation rate and char transfer rate from gasifier to combustor in a dual fluidized-bed pilot plant for biomass steam gasification

Particuology ◽

10.1016/j.partic.2019.03.004 ◽

2019 ◽

Vol 46 ◽

pp. 22-29 ◽

Cited By ~ 1

Author(s):

M. Hafizur Rahman ◽

Lius Daniel ◽

Ujash Shah ◽

Xiaotao Bi ◽

John R. Grace ◽

...

Keyword(s):

Fluidized Bed ◽

Pilot Plant ◽

Transfer Rate ◽

Steam Gasification ◽

Circulation Rate ◽

Solids Circulation Rate ◽

Dual Fluidized Bed

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An Experiment on Solid Circulation Characteristics of a Dual Circulating ﬂuidized Bed Based on Biomaterial Properties and Mechanics Properties

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.600.261 ◽

2012 ◽

Vol 600 ◽

pp. 261-264

Author(s):

Teng Ge Mi ◽

Ying Zhao ◽

Chang Qing Dong ◽

Wei Liang Cheng

Keyword(s):

Fluidized Bed ◽

Circulating Fluidized Bed ◽

Circulation Rate ◽

Gas Velocity ◽

Solid Circulation Rate ◽

Dual Fluidized Bed ◽

Bed Material ◽

Circulation Characteristics

In this paper, a dual fluidized bed has been established. The effect of bed material build-up height and gas velocity on the solid circulation rate of CFB (circulating fluidized bed) and BFB (bubble fluidized bed) has been studied. The results show that the solid circulation rate is increased with the increasing of gas velocity Uc and the bed material build-up height. Bed material build-up height of BFB and CFB is changed with the changing of gas velocity Uc. The bed material heights of CFB and BFB have been also investigated in this experiment.

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An Investigation Into the Operation of the Twin-Exit Loop-Seal of a Circulating Fluidized Bed Boiler in a Thermal Power Plant and Its Design Implication

Journal of Energy Resources Technology ◽

10.1115/1.4000174 ◽

2009 ◽

Vol 131 (4) ◽

Cited By ~ 7

Author(s):

Prabir Basu ◽

Munish Chandel ◽

James Butler ◽

Animesh Dutta

Keyword(s):

Power Plant ◽

Fluidized Bed ◽

Thermal Power Plant ◽

Circulating Fluidized Bed ◽

Thermal Power ◽

Scale Model ◽

Circulation Rate ◽

Cfb Boiler ◽

Solids Circulation Rate ◽

New Findings

Loop-seal is a critical component of a circulating fluidized bed (CFB) boiler, and yet very little information on its working or design is available in published literature. Among the limited available information, none is on twin-exit loop-seal though it is one of the most commonly used loop-seal in large commercial CFB boilers. To circulate larger amounts of solids, a twin-exit loop-seal provides larger solids flow sections. It receives solids from one standpipe but delivers it through two recycle chambers and two delivery pipes. The present research was conducted in a twin-exit loop-seal of a 3.2 MWth CFB boiler operating in a thermal power plant for cofiring purpose. Data obtained in this industrial unit were supplemented with those collected in a single-exit bench-scale loop-seal in the authors’ laboratory from the single-exit loop-seal in a 65 t/h CFB boiler and a scale model of a 30 MW CFB boiler. The effect of recycle chamber’s aeration on the solids circulation rate was studied for several particle sizes. Results suggest that the total solids circulation rate does not increase proportionately with the increase in loop-seal discharge area provided by the twin-exit loop-seals. The linear horizontal velocities of solids and the minimum aeration in the recycle chambers are comparable to those measured in a single-exit loop-seal. The implication of these new findings on the design procedure of loop-seals is discussed.

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