scholarly journals An increase in bed temperature on gasification of dual reactor fluidized bed

2018 ◽  
Vol 67 ◽  
pp. 02059
Author(s):  
I Nyoman Suprapta Winaya ◽  
I Ketut Gede Wirawan ◽  
I Wayan Arya Darma ◽  
I Putu Lokantara ◽  
Rukmi Sari Hartati
Keyword(s):  
Fluidized Bed ◽  
Gas Production ◽  
304 Stainless Steel ◽  
Fluidized Bed Reactors ◽  
Endothermic Reaction ◽  
Gasification Process ◽  
Bed Temperature ◽  
Superficial Gas Velocity ◽  
Bed Material ◽  
Co Gas

One of the main issues using biomass as fuel in air gasification is the dilution of its product gas by the nitrogen in the air. A dual reactor fluidized bed (DRFB) overcomes this problem in which the gasification and combustion reactions are decoupled and conducted in two separate fluidized bed reactors connected by circulating bed material. The DFRB unit made of 304 stainless steel pipe with a height of 100 and 150 cm, and inner diameters (i.d.) of 15.2 and 5.1 cm for gasifier and combustor respectively. The rice husk as fuel and quartz sand as bed material having the same size of 0.4 - 0.6 mm were applied in this investigation. Since the gasification process is an endothermic reaction, gasification temperatures are varied at 600°C to 700°C while combustion reactor were kept at 600°C using the electric heaters enclosed in ceramic cover. The superficial gas velocity in this study was kept constant at 17 m/s using the external air volumetric flux of the blower flow entering the DRFB loop. Gas gasification samples are then examined by gas chromatography to determine syngas content (CO, CH4 and H2). The test results showed that by the increasing temperature of the gasification reactor there was an increase in syngas especially CO gas conentration. The temperature increases in the gasification reactor (600°C, 650°C, 700°C) is able to increase the endothermic reaction in the gasification process which is dominated by CO gas production. The syngas efficiency was found to increase from 40.95% to 43.77%.as the temperature of the gasification reactor increased.

Effect of Static Bed Height on the Combustion of Rice Husk in a Fluidized Bed Combustor

2005 ◽  
Author(s):  
M. Rozainee ◽  
S. P. Ngo
Keyword(s):  
Fluidized Bed ◽  
Residence Time ◽  
Rice Husk ◽  
Bubble Formation ◽  
Combustion Process ◽  
High Heat ◽  
Transfer Rates ◽  
Bed Height ◽  
Bed Temperature ◽  
Bed Material

The combustion process is largely controlled by temperature, turbulence and residence time. When the temperature is sufficiently high so that the reaction is no longer kinetically-controlled, turbulence and residence time play a significant role. The reaction is thus diffusion-controlled. During the combustion of rice husk in a fluidized bed, the turbulence is largely governed by the mixing behavior in the inert sand bed, which in turn is governed by the bubble formation characteristics. Further, the residence time among the reactants (air and rice husk) and the heat source is also dependent on the turbulence in the bed. When all other parameters are held constant, the bubble phenomena vary according to the expanded bed height corresponding to a given static bed height. For high heat and mass transfer rates, small slowly rising bubbles are desired. Thus, the purpose of this study is to investigate the effect of static bed height on the quality of ash during the combustion of rice husk. The degree of rice husk burning in the bed could be deduced from the bed temperature as a higher bed temperature indicated that a higher portion of the rice husk feed is being burnt in the bed. Moreover, the particle size of the resulting ash is also able to give indication of the degree of rice husk burning in the bed as the turbulence arising from the bubbling action of the bed material is known to break down the char skeleton of the rice husk, thereby, resulting in ash with finer size. From this study, the static bed height of 0.5 DC was found to give the lowest residual carbon content in the ash (1.9 wt%) and the highest bed temperature (670°C) among the other range of static bed heights investigated.

Antagonism of sodium toxicity by the compatible solute betaine in anaerobic methanogenic systems

1997 ◽  
Vol 36 (6-7) ◽  
pp. 15-24 ◽  
Author(s):  
D. W. Yerkes ◽  
S. Boonyakitsombut ◽  
R. E. Speece
Keyword(s):  
Fluidized Bed ◽  
Gas Production ◽  
Compatible Solute ◽  
Fluidized Bed Reactors ◽  
Volatile Acid ◽  
Batch Reactors ◽  
Acid Uptake ◽  
Sodium Toxicity ◽  
High Concentrations ◽  
Uasb Reactors

In this paper, the compatible solute betaine is investigated for its antagonistic effects toward sodium toxicity in anaerobic methanogenic systems. Concentrations of betaine as low as 1 mM are shown to be effective at reducing the toxicity symptoms of high concentrations of sodium in the following anaerobic reactor systems: batch reactors seeded with a Methanosarcina enriched culture and batch reactors seeded with a Methanothrix culture, where the acclimation time or lag time before methane production begins is reduced significantly; CSTRs, where the acetic acid uptake rate increases dramatically; fluidized bed reactors, where gas production and pH increase and effluent COD and volatile acid concentration decrease; and UASB reactors, where gas production increases markedly. Because the phenomenon of sodium toxicity antagonism by betaine was demonstrated in anaerobic batch reactors, CSTRs, fluidized bed reactors, and UASB reactors, the usefulness of betaine in an industrial application may be feasible.

A Study of Operation Performance of Circulating Fluidized Bed Combustion Boiler

2003 ◽  
Author(s):  
Zhengshun Wu ◽  
Hanping Chen ◽  
Dechang Liu ◽  
Jie Wang ◽  
Chuangzhi Wu ◽  
...  
Keyword(s):  
Regression Analysis ◽  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Fluidized Bed Combustion ◽  
Operation Performance ◽  
Cfb Boiler ◽  
Bed Temperature ◽  
Suitable Temperature ◽  
Bed Material ◽  
Circulating Fluidized Bed Combustion

The operation performance of circulating fluidized bed combustion (CFBC) boiler was studied in this paper. The experimental results indicate that the load of CFB boiler has linear relation with bed temperature and bed material height of operation. By multiple regression analysis, the relation of the load of CFB boiler with bed temperature and bed material height of operation can be expressed as a formula. The suitable temperature and the bed material height corresponding to the load of CFB boiler can be found using the formula; the problem of the boiler to be blindly operated can be reduced in practice.

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

2007 ◽  
Vol 5 (1) ◽  
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%.

Combustion Experimental Study of Reed Black Liquor (RBL) Droplets and Particles in Fluidized Bed

2014 ◽  
Vol 694 ◽  
pp. 494-497
Author(s):  
Xing Fei Song ◽  
Ru Shan Bie ◽  
Qian Qian Liu ◽  
Xiao Yu Ji ◽  
Pei Chen ◽  
...  
Keyword(s):  
Experimental Study ◽  
Fluidized Bed ◽  
Linear Relation ◽  
Black Liquor ◽  
Gas Production ◽  
Combustion Characteristics ◽  
Production Rates ◽  
Bed Temperature ◽  
Combustion Behaviors

The experiments were carried out to investigate combustion characteristics of RBL droplets (RBLD) and RBL particles (RBLP) in fluidized bed. The combustion experiments were focused on the influence of six different bed temperatures in the ranging from 530 to 780°C on gas production rates, yields of product, carbon and hydrogen conversions, releases of Na, K and Cl and emissions of NOxand SO2. The experiments results indicate that the combustion behaviors of RBLD and RBLP mainly depend on bed temperatures. The conversions and emissions have linear relation with bed temperature, respectively. And denitrification and desulfurization processes must be had during incinerate RBL in industry application.

Adsorption of Toxic Shocks on Carriers in Anaerobic Biofilm Fluidized Bed Reactors

1993 ◽  
Vol 28 (2) ◽  
pp. 55-65 ◽  
Author(s):  
N. Mol ◽  
O. M. Kut ◽  
I. J. Dunn
Keyword(s):  
Activated Carbon ◽  
Fluidized Bed ◽  
Gas Production ◽  
Fluidized Bed Reactors ◽  
Methane Formation ◽  
Toxic Shock ◽  
Original Activity ◽  
Phenol Adsorption ◽  
Carrier Materials ◽  
The Individual

The influence of different carrier materials on the performance of single stage anaerobic biofilm fluidized bed reactors by toxic shock loadings was studied in parallel experiments. The carrier materials investigated were porous glass (Siran), quartz sand, pumice, shale, activated carbon and anthracite. Since the composition and morphology of the biofilm is influenced by the individual wastewater, vapor condensate from a sulfite cellulose process and mixed brewery wastewaters were used as substrates. The phenol adsorption characteristics were measured on bare and biofilm-coated carriers. Biofilm-coated carriers adsorbed larger amounts of phenol than bare carriers. It was observed that the biofilm morphology and the corresponding adsorption capacity of biofilm carriers depended on the individual wastewater characteristics. It was also shown that activated carbon (and partly anthracite) adsorbed large amounts of phenol, mostly irreversibly. The performance of the individual reactors was studied under short-term dynamic phenol shocks (constant hydraulic retention time (HRT) 10 h, loading rate increase from 12 to 20 kg COD/m3d during the shock period of ca.10 h). During the toxic loading in continuous operation, an increase of phenol concentration was observed in the effluent, coupled with an up to 20% decrease in the gas production rates. During this period, acetic acid accumulation was also observed, indicating the inhibition of methane formation. Following the shock, all reactors showed a relatively rapid recovery to the original activity after 2-3 hydraulic retention times.

Fluidized Bed Two-Stage Gasification Process for Clean Fuel Gas Production from Herb Residue: Fundamentals and Demonstration

2016 ◽  
Vol 30 (9) ◽  
pp. 7277-7283 ◽  
Author(s):  
Xi Zeng ◽  
Yuping Dong ◽  
Fang Wang ◽  
Pengju Xu ◽  
Ruyi Shao ◽  
...  
Keyword(s):  
Fluidized Bed ◽  
Gas Production ◽  
Two Stage ◽  
Fuel Gas ◽  
Clean Fuel ◽  
Gasification Process

Plasma-Augmented Fluidized Bed Gasification of Sub-bituminous Coal in CO2–O2 Atmospheres

2016 ◽  
Vol 35 (1) ◽  
pp. 89-101
Author(s):  
C. Lelievre ◽  
C. A. Pickles ◽  
S. Hultgren
Keyword(s):  
Fluidized Bed ◽  
Energy Minimization ◽  
Bituminous Coal ◽  
Minimization Method ◽  
Gasification Process ◽  
Coal Gasifier ◽  
Bed Temperature ◽  
Gibbs Free Energy Minimization ◽  
Fluidized Bed Gasifier ◽  
Hsc Chemistry

AbstractThe gasification of a sub-bituminous coal using CO2–O2 gas mixtures was studied in a plasma-augmented fluidized bed gasifier. Firstly, the coal was chemically characterized and the gasification process was examined using Thermogravimetric and Differential Thermal Analysis (TGA/DTA) in CO2, O2 and at a CO2 to O2 ratio of 3 to 1. Secondly, the equilibrium gas compositions were obtained using the Gibbs free energy minimization method (HSC Chemistry®7). Thirdly, gasification tests were performed in a plasma-augmented fluidized bed and the off-gas temperatures and compositions were determined. Finally, for comparison purposes, control tests were conducted using a conventional fluidized bed coal gasifier and these results were compared to those achieved in the plasma-augmented fluidized bed gasifier. The effects of bed temperature and CO2 to O2 ratio were studied. For both gasifiers, at a given bed temperature, the off-gas compositions were in general agreement with the equilibrium values. Also, for both gasifiers, an experimental CO2 to O2 ratio of about 3 to 1 resulted in the highest syngas grade (%CO + %H2). Both higher off-gas temperatures and syngas grades could be achieved in the plasma-augmented gasifier, in comparison to the conventional gasifier. These differences were attributed to the higher bed temperatures in the plasma-augmented fluidized bed gasifier.

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