Feasible Experimental Study on the Utilization of a 300MW CFB Boiler Desulfurizating Bottom Ash for Construction Applications

2005 ◽  
Vol 128 (4) ◽  
pp. 311-318 ◽  
Author(s):  
Xiaofeng Lu ◽  
R. S. Amano
Keyword(s):  
Experimental Study ◽  
Power Plant ◽  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Bottom Ash ◽  
Base Material ◽  
Cfb Boiler ◽  
Road Base ◽  
Study Results ◽  
Disposal Cost

Circulating fluidized bed (CFB) boiler has entered electric power industry field because of burning a wide range of fuels, while still achieving strict air emissions requirements. This study focuses on a 300MW CFB boiler, which will be one of the largest CFB boiler in the world. In a CFB boiler, fuels were burned with the addition of limestone to capture SO2 in a solid form. Therefore, the volume of ashes, both bottom ash and fly ash, discharged from a CFB boiler is much higher than the ashes discharged from a pulverized coal-fired (PC) boiler at the same capacity of the boiler. CFB boiler ash cannot be used as a cement replacement in concrete due to its unacceptably high sulfur content. The disposal in landfills has been the most common means of handling ash in circulating fluidized bed boiler power plants. However, for a 300MW CFB boiler power plant, there will be 600,000tons of ash discharged per year and will result in great volumes and disposal cost of ash byproduct. It was very necessary to solve the utilization of CFB ash and to decrease the disposal cost of CFB ash. The feasible experimental study results on the utilization of the bottom ashes of a 300MW CFB boiler in Baima power plant in China were reported in this paper. The bottom ashes used for test came from the discharged bottom ashes in a 100MW CFB boiler in which the anthracite and limestone designed for the 300MW CFB project was burned. The results of this study showed that the bottom ash could be used for cementitious material, road concrete, and road base material. The masonry cements, road concrete with 30MPa compressive strength and 4.0MPa flexural strength, and the road base material used for base courses of the expressway, the main road and the minor lane were all prepared with milled CFB bottom ashes in the lab. The better methods of utilization of the bottom ashes were discussed in this paper.

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

2009 ◽  
Vol 131 (4) ◽  
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.

Performance evaluation of a supercritical circulating fluidized bed boiler for power generation under flexible operation

2021 ◽  
pp. 095765092199396
Author(s):  
Matteo Bruzzone ◽  
Silvia Ravelli
Keyword(s):  
Power Generation ◽  
Fluidized Bed ◽  
High Performance ◽  
Circulating Fluidized Bed ◽  
Thermal Power ◽  
Rankine Cycle ◽  
Hard Coal ◽  
Cfb Boiler ◽  
Power Cycles ◽  
Commercial Code

It is well known that the Łagisza power plant in Poland is the world’s first supercritical circulating fluidized bed (CFB) boiler, whose commercial operation started on June 2009. It has attracted a great deal of interest and operational data are publicly available, therefore it has been chosen as the object of the present study aimed at assessing load and fuel flexibility of supercritical CFB plants. First, the thermal cycle was modelled, by means of the commercial code Thermoflex®, at nominal and part load conditions for validation purposes. After having verified the validity of the applied modelling and simulation tool, the advantage of having supercritical steam combined with CFB boiler over subcritical steam and pulverized coal (PC) boiler, respectively, was quantified in terms of electric efficiency. As a next step, the designed fuel, i.e. locally mined hard coal, was replaced with biomass: 100% biomass firing was taken into account in the case of subcritical CFB boiler whereas the maximum share of biomass with coal was set at 50% with supercritical CFB boiler, consistently with the guidelines provided by the world leading manufacturers of CFB units. A broad range of biomass types was tested to conceive mixtures of fuel capable of preserving quite high performance, despite the energy consumption in pretreatment. However, the overall efficiency penalty, due to biomass co-firing, was found to potentially undermine the benefit of supercritical steam conditions compared to conventional subcritical power cycles. Indeed, the use of low-quality biomass in thermal power generation based on steam Rankine cycle may frustrate efforts to push the steam cycle boundaries.

Experimental Study of Solids Motion in an 18 m Gas–Solids Circulating Fluidized Bed with High Solids Flux

2019 ◽  
Vol 58 (51) ◽  
pp. 23468-23480 ◽  
Author(s):  
Xin Su ◽  
Chengxiu Wang ◽  
Huajian Pei ◽  
Jingya Li ◽  
Xingying Lan ◽  
...  
Keyword(s):  
Experimental Study ◽  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
High Solids

scholarly journals Feasibility Study of Using Carbide Slag as In-Bed Desulfurizer in Circulating Fluidized Bed Boiler

2019 ◽  
Vol 9 (21) ◽  
pp. 4517 ◽  
Author(s):  
Zhong Huang ◽  
Jimiao Long ◽  
Lei Deng ◽  
Defu Che
Keyword(s):  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Separation Efficiency ◽  
Molar Fraction ◽  
So2 Emissions ◽  
Cfb Boiler ◽  
Carbide Slag ◽  
Desulfurization Efficiency ◽  
Sintering Resistance ◽  
Pilot Tests

Carbide slag is a waste residue during the production of acetylene. Due to its high content of Ca(OH)2, carbide slag becomes a potential alternative to limestone as the in-bed desulfurizer of circulating fluidized bed (CFB) boilers. In this study, the calcination and sulfation characteristics of carbide slag were investigated by three different facilities, thermogravimetric analyzer (TGA), 1 MWth pilot CFB boiler, and 690 t·h−1 CFB boiler. Pore structures and sulfation behaviors of carbide slag and limestone were investigated for the sake of comparison. The results showed that carbide slag has a lower calcination temperature than limestone. Its calcined product has a better pore structure and desulfurization activity. The carbide slag exhibited a higher desulfurization efficiency than the limestone in the pilot tests. The SO2 emission concentration showed a downward trend with the increase of molar fraction of carbide slag in the desulfurizer. Meanwhile, carbide slag had a better sintering-resistance property, which makes it possible to effectively reduce SO2 emissions even at high combustion temperatures (>910 °C). While the field test results were similar to that of the pilot tests, the desulfurization efficiency of carbide slag with the same Ca/S mole ratio was higher than that of limestone. The fine size of carbide slag particles and the lower separation efficiency of the cyclone on the 690 t·h−1 boiler left the carbide slag with insufficient residence time in the furnace. Therefore, it is necessary to ensure a high separation efficiency of the cyclone if the carbide slag is used as an alternative desulfurizer in furnace.

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