• 한국연소학회:학술대회논문집
• /
• 2002.06a
• /
• pp.212-219
• /
• 2002

Waste fuels, which originate from different sources, have unique combustion characteristics. The characteristics should be considered in applying FBC(fluidized bed combustor) technology to those fuels. The effects of fuel properties and operating conditions on FBC reactivity were investigated by means of carbon based parameter called mean carbon conversion time, rate of carbon conversion, fraction of carbon conversion and carbon recovery. And the basic physical and chemical mechanisms taking place in a fluidized bed were summarized. Major parameters in designing and operating FBC were evaluated in terms of the fuel properties and the combustion environment.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.48 no.6
• /
• pp.475-482
• /
• 1999

The electrostatic precipitation characteristics of two kinds of fly ashes, one derived from a fluidized bed combustor(FBC), the other from a pulverized coal(PC) fired furnace, have been studied on a pilot plant. Experiments have been carried out to enhance the collection efficiency while changing the operating conditions for two kinds of coal ashes, respectively. It has been shown that collection efficiency is affected by many factors such as shape of the ashes, dust contents, humidity, and temperature, etc. Experimantal results showed that collection efficiency of the FBC ashes was higher than that of the PC fly ash in spite of the small size of the FBC ashes. The experimetal results have been applied to the collection efficiency equations to show that the modified Deutsch equation was well agreed with experiment results if modification parameter k was set to 0.6 for the fluidized bed fly ashes and to 0.43 for the pulverized coal fly ashes.

• 한국연소학회:학술대회논문집
• /
• 2002.06a
• /
• pp.199-203
• /
• 2002

In this paper, the effects of water contents on combustion characteristics of paper sludge and capacity of fluidized bed combustor(FBC) were investigated using 0.26m diameter, 1.75m height pilot-plant scale combustor. Combustion tests of paper sludge containing water contents between 40wt% and 50wt% were performed. The temperature and emission variation, the pressure inside combustor were measured to monitor the fluidization quality. The experimental results showed that 30kg/hr feeding rate of sludge containing water up to 45wt% was preferable for this system. Sludge loading rate, heat release rate were calculated from experimental data as major parameters showing FBC capacity. Comparsion with sludge loading rate from other source was also performed

• 한국연소학회:학술대회논문집
• /
• 2000.12a
• /
• pp.236-245
• /
• 2000

A laboratory scale fluidized bed reactor was developed to treat the combustion characteristics of some fuels (wood, paper sludge, refuse derived fuel). The aims were to introduce the means of experiment and interpretation of the results and finally determine the particle characteristics on the pyrolysis and combustion process of the fuel. A single particle combustion process in the fluidized bed was closely observed. Understanding experimental facility characteristics and determining parameters were also carried out. The fuel combustion processes were observed by carbon conversion rate, recovery and mean carbon conversion time. They were estimated with the CO, $CO_2$ gas concentration monitored at the exit of the combustor. Fuel drying and pyrolysis process were governed by temperature distribution in the fuel particle. There was a significant overlap of the drying and devolatilization. However, transition process from devolatilization to char combustion seemed to be determined by mechanical solidity of the fuel particle after devolatilization process.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.24 no.5
• /
• pp.677-686
• /
• 2000

The characteristics of combustion and of emissions in pressurized fluidized bed combustor are investigated. The pressure of the combustor is fixed at 6 atm, and the combustion temperatures are set to 850, 900, and $950^{\circ}C$. The gas velocities are 0.9, 1.1, and 1.3 m/s. The excess air ratio is varied from 5 to 35%. The coal used in the experiment is Shenhwa coal in China. All experiments are executed at 2m bed height. Consequently, NOx & $N_2O$ concentration in the flue gas is increased with incresing excess air ratio but $SO_2$ concentration is decreased with incresing excess air ratio. CO concentration is maintained below 100ppm at over 15% of excess air ratio.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.21 no.6
• /
• pp.747-757
• /
• 1997

A numerical investigation of the fuel concentration field in a fluidized bed has been carried out for the scale-up of a fluidized bed combustor (FBC). A two-dimensional transient model is developed using the two-phase fluidization, a simple chemical reaction, and lateral solid mixing theories. The uniformity of fuel concentration distributions is controlled by the location and the number of fuel feeders, fluidizing velocities and the bed-heights. While larger bubbles owing to greater fluidizing velocities enhance the fuel-dispersion in the bed, they have adverse effects on fuel combustion and thus result in the increase of fuel concentration, since a greater bubble means a larger bypass which reduces gas-exchange rates between bubble and emulsion phases. Average or maximum values of the bed fuel concentration are utilized as criteria for the scale-up from a pilot/lab-scale to a commercial-size bed.

• Journal of the Korean Society of Combustion
• /
• v.1 no.1
• /
• pp.1-10
• /
• 1996

An effective scale-up methodology of fluidized bed incinerators for low calorific value industrial wastes such as paper sludge and sewage sludge has been developed based on the similarity rules. Conventional scale-up theories are briefly reviewed and a new simple theory defining the diffusion Fourier number is established taking account of the lateral mixing of fuels in the fluidized bed. From the design and the operating conditions of the pilot FBC plant at Inchon, important design data for the full-scale incinerators are calculated and discussed.

• 한국연소학회:학술대회논문집
• /
• 2001.11a
• /
• pp.142-152
• /
• 2001

Three Lab-scale combustors of different types were made to observe some basic phenomena of fuel combustion in the combustors ; grate type combustor, rotary kiln and FBC. The aims were to introduce how to simulate the combustion behaviors in the real plants by utilizing the reduced apparatuses and characterize the combustors relating to some important parameters such as fuel size, water contents, bed temperature, rotating speed of kiln, flow rate. The mean carbon conversion time and the flame propagation rate were adopted for the quantitative analysis.

• Journal of the Korean Society of Combustion
• /
• v.9 no.3
• /
• pp.1-9
• /
• 2004

This study is aimed to characterize the combustion behavior of solid fuel in the various types of the combustors: stoker, rotary kiln and fluidized bed type combustors. Three different types of reduced-scale combustors are introduced, and temperatures and flue gas compositions are measured for various fuel sizes, water contents, initial temperature, and air flow rates. In case of the rotary kiln combustor, effects of rotating speed of the combustor are also investigated. Mean carbon conversion time (MCCT) and flame propagation rate (FPR) are used for the quantitative analysis. It is revealed that the reaction rates of the fuel are significantly influenced by the fuel characteristics, type of the combustors and air flow rate. Major design parameters for each type of the combustors are summarized through the reduced-scaled model analysis.

• 한국연소학회:학술대회논문집
• /
• 1999.10a
• /
• pp.81-91
• /
• 1999

Fuel characteristics of sewage sludge as required for the fluidized bed incinerators have been evaluated. Sewage sludge is basically a solid fuel with high percentage of moisture. Moisture content of the fuel directly affects the heating value of the fuel and the exhaust gas composition. When the sludge of transported into the incinerator, sludge cake is subject to the mixing, break-up and heat-up. Fluidization process would enhance these physical processes. The sludge fuel could then undergo the moisture evaporation and devolatilization process. Subsequent oxidation of volatiles as well as the remaining char would then follow. Sludge samples are characterized with high percentage of volatiles out of total combustibles. Quantitative understanding of above listed subprocesses would certainly help in the utilization of fluidized bed incinerators. A limited set of fuel characterization tests including calorimetric analysis, proximate analysis, elemental analysis and thermogravimetric analysis were conducted for the selected sludge samples. The measurement reasults of sludge samples were reported along with some published data. Limited experience in the actual incinerator plant is also presented.