Study on the Optimal Running Temperature of Circulating Fluidized Bed Boiler Burning Fujian Anthracite

2013 ◽  
Vol 732-733 ◽  
pp. 291-296
Author(s):  
Hong Zhou He ◽  
Huang Huang Zhuang
Keyword(s):  
Fly Ash ◽  
Carbon Content ◽  
Circulating Fluidized Bed ◽  
Cfb Boiler ◽  
Industrial Experiments ◽  
Boiler Efficiency ◽  
Efficient Combustion ◽  
Desulfurization Efficiency ◽  
Burnout Rate ◽  
Very High

There is a contradiction in selecting the running temperature for CFB boilers burning Fujian anthracite, in order to simultaneously satisfy the requirement of efficient combustion and high desulfurization efficiency. Based on numerical simulation and industrial experiments, the effect of the running temperature on the carbon content in fly ash and the desulfurization efficiency were analyzed for two types of CFB boilers with different capacities. It is found that, with the rise of running temperature, both decrease quasi-linearly. For the 75 t/h CFB boiler, when the running temperature is lower than 950 °C, the carbon content in fly ash is very high, causing a low burnout efficiency; maintaining the running temperature at 1000 °C is favorable for the fine char to be burned out, however, continuous raise becomes almost useless. For 440 t/h CFB boiler, a higher burnout rate of the fine char particles can be obtained when the running temperature is kept at about 950 °C, and further increase brings no evident benefit either. For the 75 t/h and 440 t/h CFB boilers burning Fujian anthracite, considering both the boiler efficiency and the combustion desulfurization efficiency, the optimal running temperature should be respectively about 980 °C and 950 °C.

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.

Properties of Particles in the Fly Ash of a Biofuel-Fired Circulating Fluidized Bed (CFB) Boiler

2008 ◽  
Vol 22 (5) ◽  
pp. 3005-3015 ◽  
Author(s):  
Linda S. Johansson ◽  
Bo Leckner ◽  
Claes Tullin ◽  
Lars-Erik Åmand ◽  
Kent Davidsson
Keyword(s):  
Fly Ash ◽  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Cfb Boiler

Experimental Study of CFB Modification Fly Ash in Concrete

2014 ◽  
Vol 1051 ◽  
pp. 743-747 ◽  
Author(s):  
Rong Jin Xu ◽  
Yan Kai Huo ◽  
Bin Teng ◽  
Si Hai Song
Keyword(s):  
Experimental Study ◽  
Fly Ash ◽  
Carbon Content ◽  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Pulverized Coal ◽  
Experimental Results ◽  
Unburned Carbon ◽  
Fluidized Bed Combustion ◽  
Effective Use

The character of the Fly ash of Circulating Fluidized Bed Boiler (CFB Fly ash) is greatly different from that of Pulverized coal furnace for its high unburned carbon. In order to make effective use of CFB Fly ash in concrete, carbon content was decreased by simulated fluidized bed combustion in laboratory and a series of concerned experiments were carried out on CFB Fly ash. The experimental results indicate that CFB modification Fly ash is possible to be used in concrete to partially replaced cement. It is a valuable reference for CFB Fly ash technical engineers.

scholarly journals Combustion adjustment and operation optimiztion of a 240 t/h circulating fluidized bed boiler

2020 ◽  
Vol 24 (5 Part A) ◽  
pp. 2689-2698
Author(s):  
Xuemin Liu ◽  
Songsong Zhang ◽  
Yongqiang Chang ◽  
Zhongwei Wang ◽  
Guoli Qi
Keyword(s):  
Fly Ash ◽  
Pressure Drop ◽  
Fluidized Bed ◽  
Flue Gas ◽  
Circulating Fluidized Bed ◽  
Air Flow ◽  
Nox Emission ◽  
Unburned Carbon ◽  
Boiler Efficiency ◽  
Co Concentration

The influence of main operating parameters on boiler performance was studied, such as bed pressure drop, primary air-flow and secondary air-flow. Combustion adjustment tests were carried out on a circulating fluidized bed boiler with rated capacity of 240 t/h. From the test results, it can be seen that the loss due to exit flue gas is the largest heat loss of the boiler, accounting for more than 70% of the total heat losses. For coal fired boilers, compared with the loss due to unburned solids, the loss due to unburned gases is quite small. The unburned carbon con-tent in bottom ash is far lower than the value in fly ash. The trend of CO concentration in the exit flue gas is similar to that of the unburned carbon content in fly ash. To achieve higher boiler efficiency, the bed pressure drop is suggested to be maintained in about 8.5-9.0 kPa and the oxygen content in exit flue gas around 4%. The NOx emission concentration usually presents a negative correlation with CO concentration in exit flue gas. Through combustion adjustment and operation optimization, the NOx emission can be decreased by about 30% without affecting the boiler efficiency.

The Study on the Characteristics of Fly Ash From CFB

2008 ◽  
Author(s):  
Qian Yang ◽  
Yong Tao Yuan ◽  
Li Qiang Qi
Keyword(s):  
Fly Ash ◽  
Carbon Content ◽  
Fluidized Bed ◽  
Mineral Composition ◽  
Distinctive Feature ◽  
Circulating Fluidized Bed ◽  
Element Composition ◽  
The Other ◽  
Coal Fire ◽  
Component Form

The element and mineral composition and the physical characteristics of fly ash from circulating fluidized bed boiler, are different to the other kinds of boilers. The aim of the study was to discuss the distinctive feature between the fly ash from CFB and the fly ash from pulverized coal fire boiler. The experiments show that the change of element composition from CFB and PC boiler has the some rule with the change of granularity. The carbon content of residua from CFB is higher than the content from PC boiler obviously. The SiO2 dioxide content decreases with the granularity of residua fining, while the content of Al2O3, CaO, MgO has the reverse rule in despite of CFB or PC boiler. The content of TFeO of residua increases in CFB while the content decreases in PC boiler with the granularity of residua fining. And the component form of TFeO in CFB is mainly Fe2O3 while the component in PC boiler is mainly Fe3O4. The higher the content of carbon was, the lower the special resistance was.

Experimental Study on Microstructure of Fly-Ash from Circulating Fluidized Bed Boilers

2011 ◽  
Vol 354-355 ◽  
pp. 413-416
Author(s):  
Yan Jin ◽  
Cui Ying Feng ◽  
Juan Juan Liu
Keyword(s):  
Fly Ash ◽  
Fluidized Bed ◽  
Adsorption Isotherms ◽  
Circulating Fluidized Bed ◽  
Nitrogen Adsorption ◽  
Cfb Boiler ◽  
Nitrogen Adsorption Isotherms ◽  
Pore Types ◽  
Adsorption Desorption ◽  
Fluidized Bed Boilers

Circulating fluidized bed (CFB) combustion techniques have been widely used in China. In order to improve CFB boiler performance it is necessary to study on microstructures of fly-ash. With the help of nitrogen adsorption instrument and scanning electron microscopy, the pore structure of fly-ash in circulating fluidized bed boilers are studied by nitrogen adsorption/desorption isotherms of fly-ash, hysteresis loop and pore distribution. The results indicated that different particle sizes of fly-ash in CFB boilers are of similar nitrogen adsorption isotherms, pore types and the pore size distribution, and the most probable pore radius of fly-ash is about 2nm. Adsorption isotherms of fly-ash is the second type, and the macro-porous and meso-porous types are tapered hole, parallel plate slit hole and the ink bottle shape hole. And meso-pore in proportion is the largest. Micro-pores are not discovered in fly-ash from CFB boilers.

Study of Efficiency Improvement and Optimization in CFB

2016 ◽  
Author(s):  
Ajay Natraj Shastri
Keyword(s):  
Power Generation ◽  
Circulating Fluidized Bed ◽  
Extensive Study ◽  
Efficiency Improvement ◽  
Discussion Paper ◽  
Environment Friendly ◽  
Cfb Boiler ◽  
World Power ◽  
Boiler Efficiency ◽  
Coal Technology

Circulating fluidized bed (CFB) boiler technology now-a-days is becoming dominant in the coal fired power generation across the globe; It is now biggest competitor to PC fired coal technology reason being fuel flexible, environment friendly, less water consumption along with cost benefits. Major Challenges such as efficiency improvement and adaptability to advance technologies such as SC, USC, and A-USC is becoming need of the future. World power generation industry going through tough challenge of abating carbon emission and greenhouse gases at the same time providing cheap, reliable and quality electricity. To cater this CFB being the popular choice, efficiency improvement in CFB has become mandatory. This paper aims to provide limelight on optimizing the efficiency aspects of CFB boiler, various fuels and fuel-mixes available through extensive study material. Paper will also address the boiler efficiency aspects as per ASME PTC 4.0. At the end of the discussion, paper concludes with recommendations for efficiency improvement in CFB boiler aims to be useful for researcher, clients, developer, and investors.

scholarly journals Utilization of Circulating Fluidized Bed Fly Ash as Pozzolanic Material

2017 ◽  
Vol 11 (1) ◽  
pp. 176-186 ◽  
Author(s):  
Kae- Long Lin ◽  
Ta-Wui Cheng ◽  
Chih-Hsuan Ho ◽  
Yu-Min Chang ◽  
Kang-Wei Lo
Keyword(s):  
Fly Ash ◽  
Fluidized Bed ◽  
Petroleum Coke ◽  
Circulating Fluidized Bed ◽  
Blended Cement ◽  
Curing Time ◽  
Cement Pastes ◽  
Cfb Boiler ◽  
Pozzolanic Material ◽  
High Sulfur Content

A circulating fluidized bed (CFB) boiler generates energy by burning petroleum coke. Because burnt petroleum coke has a high sulfur content, limestone is added to the boiler to reduce the emittance of sulfur dioxide through desulfuration. The residue collected from the boiler is called CFB ash. CFB boilers in Taiwan can produce 328,000 tonnes of CFB fly ash per year. In this study, the pozzolanic characteristics of CFB fly ash were investigated by blending CFB fly ash and ordinary Portland cement (OPC). The CFB fly ash was mainly composed of CaO, SO3, and SiO2 in concentrations of 37.8%, 9.2%, and 2.2%, respectively. The crystals of CFB fly ash contained 3CaO.SiO2, 2CaO.SiO2, Ca(OH)2, C-S-H (Tobermolite), and Ettringite. The results revealed that applying the toxicity characteristic leaching procedure to CFB fly ash renders it suitable for use in blended cement. At later curing ages (90 days), the pore volumes of both the OPC and the CFB-fly-ash-blended cement pastes (CFBFABCP) decreased as the curing time increased. A possible explanation is that C3S and C2S were consumed to form C-S-H gel, resulting in an increase in the Q1 and Q2 groups identified by 29Si Nuclear Magnetic Resonance (NMR) spectroscopy. Furthermore, the peak of the Q0 group decreased, but those of the Q1 and Q2 peaks increased with an increasing curing time. The pozzolanic activity of the CFBFABCP containing 10% CFB fly ash indicates that it is a suitable substitute for OPC in blended cement.

scholarly journals Utilization of CFBC Fly Ash as a Binder to Produce In-Furnace Desulfurization Sorbent

2018 ◽  
Vol 10 (12) ◽  
pp. 4854 ◽  
Author(s):  
Chulseoung Baek ◽  
Junhyung Seo ◽  
Moonkwan Choi ◽  
Jinsang Cho ◽  
Jiwhan Ahn ◽  
...  
Keyword(s):  
Fly Ash ◽  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Coal Ash ◽  
Limestone Powder ◽  
Fluidized Bed Combustion ◽  
High Concentration ◽  
Cfbc Fly Ash ◽  
Desulfurization Efficiency ◽  
Free Cao

Circulating fluidized bed combustion (CFBC) power generation technology is known to efficiently reduce the emission of air pollutants, such as SO2 and NO2, from coal combustion. however, CFBC coal ash contains high contents of free CaO, making it difficult to recycle. This research has been conducted to find ways to use the self-hardening property of CFBC coal ash, one of its inherent characteristics. As part of these efforts, the present study intended to investigate the properties and desulfurization efficiency of Ca-based desulfurization sorbents using CFBC fly-ash as a binder. Limestone powder was mixed with CFBC fly-ash and Ca(OH)2 to fabricate desulfurization sorbents, and it generated hydrate of cement, including portlandite, ettringite, and calcium silicate, etc. The compressive strength of the desulfurization absorbent prepared by CFBC fly ash and Ca(OH)2 was 72–92% that of the desulfurized absorbent prepared by using general cement as a binder. These absorbents were then compared in terms of desulfurization efficiency using a high-temperature fluidized bed reactor. It was confirmed that the desulfurization absorbents fabricated using CFBC fly-ash as a binder achieved the best performance in terms of absorption time, which reflects the time taken for them to remove over 90% of high-concentration SO2 gas, and the conversion ratio, which refers to the ratio of CaO turning into CaSO4.

The Experimental Study of SO2 Removal by Atomized Ammonia Injection in the Tail Flue of a 300 MW CFB Boiler

2014 ◽  
Vol 1010-1012 ◽  
pp. 547-550
Author(s):  
Ri Guang Wei ◽  
Shao Wei Cheng ◽  
Jian Qiang Gao
Keyword(s):  
Experimental Study ◽  
Fly Ash ◽  
Removal Efficiency ◽  
Activation Function ◽  
Ammonia Concentration ◽  
Gas Temperature ◽  
Unit Load ◽  
Cfb Boiler ◽  
Desulfurization Efficiency ◽  
Ammonia Injection

An experimental study on the desulfurization system by atomized ammonia injection was conducted in the tail flue of a 300MW CFB boiler. The tests was going under the unit load ranges from 229.5MW to 267MW with ammonia concentration of 5.2~9% and flow at 3.7~9.0 t/h, the gas temperature at 145~149°C, the maximum final desulfurization efficiency is 55.6%, the average removal efficiency at 21% ~ 26%. The ammonia also has an activation function to the CaO in fly ash, which counts 15.7% to 29.8% of the total amount CaO in fly ash.

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