• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.49 no.10
• /
• pp.570-576
• /
• 2000

The discharge and the collection efficiency characteristics of an electrostatic precipitator have been studied under various operating conditions. The specific resistivity of pulverized coal dust was about 1013∼1014[${\Omega}{\cdot}cm$] and reached the maximum value of 6${\times}$1013[${\Omega}{\cdot}cm$] at 150[$^{\circ}C$]. Back corona has been occurred as dust contents and gas temperature increase. In the case of back corona occurrence, collection effciency decreased rapidly. This problem has been solved by increasing moisture contents. Experimental results showed that collection efficiency of the full wave voltage was higher than that of the pulse wave voltage. The modification parameter k of the collection efficiency equation was about 0.42.

• Journal of the Korean GEO-environmental Society
• /
• v.8 no.2
• /
• pp.57-63
• /
• 2007

Coal combustion by-product (CCB) bottom ash, obtained from burning of pulverized coal, has physical properties which are similar to that of natural sand with particle sizes ranging from fine gravel to fine sand. Several studies have been completed to utilize pulverized coal combustion (PCC) bottom ash as a partial or full replacement of fine aggregate in cement concrete products. The objectives of this study were to develop air-entrained concrete composites using PCC bottom ash from burning of Illinois coal and to demonstrate the use of these composites on real-world projects. The results obtained show that the compressive, splitting-tensile, and flexural strengths of concrete composites is slightly lower than that of conventional concrete are early curing ages. However, after 60 days of curing, the strength of concrete composites is either equal to or slightly higher than that of an equivalent conventional concrete. The concrete composites showed lower resistance to chloride ion penetrability than that of an equivalent conventional concrete at early curing ages. However, after 28 days of curing, concrete composites showed better resistance to chloride ion penetrability compared to that of an equivalent conventional concrete.

• Journal of the Korean Society of Combustion
• /
• v.21 no.4
• /
• pp.30-38
• /
• 2016

Flame structure of co-firing coal and palm kernel shell (PKS) was investigated in a pulverized coal swirl burner by particle image velocimetry (PIV). The pulverized coal swirl flame is operated with a PKS blending ratio of 10%, 20%, and 30%. For all operating conditions, flame structures such as internal recirculation zone (IRZ), outer recirculation zone (ORZ), and exhaust tube vortex (ETV) were observed. In the center of flame, the strong velocity gradient is occurred at the stagnation point where the volatile gas combustion actively takes place and the acceleration is increased with higher PKS blending ratio. OH radical shows the burned gas region at the stagnation point and shear layer between IRZ and ORZ. In addition, OH radical intensity increases for a co-firing condition because of high volatile matter from PKS. Because the volatile gas combustion takes place at lower temperature, co-firing condition (more than 20%) leads to oxygen deficiency and reduces the combustibility of coal particle near the burner. Therefore, increasing PKS blending ratio leads to higher OH radical intensity and lower temperature.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.34 no.11
• /
• pp.957-964
• /
• 2010

The deflagration-to-detonation transition (DDT) causes a strong pressure wave that can adversely affect surrounding structures. The pressure generated by multiple detonative pulses is strong enough to cause metal surface erosion and chipping of the edges of bulk structures. In this study, we investigate the damage caused by the DDT phenomenon and perform hydrocode simulations to evaluate the structural damage caused to a metallic pulverized-coal injector used in a pulverized-coal-oxygen combustion furnace. The experimental conditions are selected in order to accurately model the damage caused to metal injectors that are exposed to multiple DDT pulses.

• Proceedings of the KSME Conference
• /
• 2001.11b
• /
• pp.764-769
• /
• 2001

Recently, according to increase in the requirement of electric power, a thermoelectric power plant equipped with pulverized coal combustion system is highly valued, because coal has abundant deposits and a low price compared with others. For efficient use of coal fuel, most of plant makers are studying to improve combustion performance and flame stability, and reduce pollutant emission. One of these studies is how to control the profile of particle injection and velocity dependant on coal nozzle. Basically, a mixed flow of gas and particle in coal nozzle is required to have appropriate injection and concentration distribution at exit to achieve flame stability and low pollutant, but it is very difficult to obtain that without help of a coal separating device within nozzle. In this study, each distribution of air and coal flow rate is measured for the coal nozzle with coal separator developed by us. The coal concentration at exit is various according to inlet swirl values and positions of coal separator. Also pressure drop is measured for various operating conditions of this nozzle. From these results, we can find the separation characteristic of new developed coal separator, and select proper operation range of coal nozzle. When this coal nozzle is applied to actual plant, these investigations will be very useful to confirm the shape of coal separator to have efficient particle injection.

• Journal of Energy Engineering
• /
• v.26 no.4
• /
• pp.118-126
• /
• 2017

This study was performed to investigate the characteristics of combustion and emissions in pulverized coal fired boiler for using high moisture coal and dry coal through computational fluid dynamics(CFD). We validated this boiler model with performance data of the boiler. The results of flow characteristics showed that climbing speed of gases was increased as blending ratio of high moisture coal was increased. It can decrease a residence time of fuel in the furnace. And it influence coal combustion. The coal burnout and NOx generation in burner level were decreased as increasing blending ratio of high moisture coal. The gas temperature and NOx formation were increased after OFA level due to coal burnout delay.

• Clean Technology
• /
• v.23 no.1
• /
• pp.73-79
• /
• 2017

Recently usage of biomass is increased in pulverized coal power plants for reduction of $CO_2$ emission. Many problems arise when thermal share of the biomass is increased, and milling of the biomasses is one of the most important problems due to their low grindability when existing coal pulverizer is used. Grindability of coal can be measured through the HGI (Hardgrove grindability index) equipment as a standard, but method of measuring biomass grindability has not been established yet. In this study, grinding experiment of coal and biomass was performed using a lab-scale ball mill. One type of coal (Adaro coal) and six biomasses (wood pellet (WP), empty fruit bunch (EFB), palm kernel shell (PKS), walnut shell (WS), torrefied wood chip (TBC) and torrefied wood pellet (TWP)) were used in the experiment. Particle size distributions of the fuels were measured after being milled in various pulverization times. Pulverization characteristics were evaluated by portion of particles under the diameter of $75{\mu}m$. As a result, about 70% of the TBC and TWP were observed to be pulverized to sizes of under $75{\mu}m$, which implies that they can be used as alternative biomass fuels without modification of the existing mill. Other biomass was observed to have low grindability compared with torrefied biomass. Power consumption of the mill for various fuels was measured as well, and the results show that lower power was consumed for torrefied biomasses. This result can be used for characterization of biomass as an alternative fuel for pulverized coal power plants.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.34 no.3
• /
• pp.259-267
• /
• 2010

In this study, the effect of particle size on the combustion characteristics of pulverized sub-bituminous coal was experimentally investigated. A laminar-flow-entrained reactor was designed and implemented to realize the desired heating ratio and temperature corresponding to the combustion atmosphere of a pulverized-coal-fueled furnace. The flame length and structure of burning particles according to different sizes were investigated. Coal combustion processes were clearly distinguished by direct visual observation of the flame structure. The onset point of volatile ignition is greatly affected by changes in the particle size, and the burning time of the volatiles is least affected by changes in the particle size. The length and instability of char flame also increase with the increase of the particle size. However, the char consumption rate within the residential time remains nearly constant.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.9
• /
• pp.27-33
• /
• 2016

Phenolic resin has excellent heat resistance and good mechanical properties as a thermosetting resin. However, its thermosetting characteristics cause it to produce a non-recyclable waste in the form of sprue and runner which is discarded and represents up to 15~20% of the overall products. Forty thousand tons of phenolic resin sprue and runner are disposed of (annually). The (annual) cost of such domestic waste disposal is calculated to be 20 billion won. In this study, discarded phenol resin scraps were pulverized and treated by silanes to improve their interfacial adhesion with HDPE. The sizes of the pulverized pulverulent bodies and fine particles were (100um~1000um) and (1~100um), respectively. The pulverized phenol resin was treated with 3-(methacryloyloxy) propyltrimethoxysilane and vinyltrimethoxy silane and the changes in its characteristics were evaluated. The thermal properties were evaluated by DSC and HDT. The mechanical properties were assessed by a notched Izod impact strength tester. When the silane treated phenol resin was added, the heat distortion temperature of HDPE increased from $77^{\circ}C$ to $96^{\circ}C$ and its crystallinity and crystallization temperature also increased. Finally, its impact strength and tensile strength increased by 20% and 50%, respectively, in comparison with the non-treated phenol resin.

• 한국연소학회:학술대회논문집
• /
• 2014.11a
• /
• pp.351-354
• /
• 2014