At present, coalfired power plants mainly involve pulverized coal combustion and a great amount of coal combustion solid residue continues to be formed from power plants. Querol et al. [2] have estimated the worldwide production of coal ash to exceed 550 × 10 6 tonnes/year. Fly ash is defined as the fraction of fine ash particles that is ...
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To explore methods of reducing NOx emission from pulverized coal boilers, the effects of injecting ammonia solution and pyrolysis gas into the furnace on NOx emission were experimentally investigated on a 75 t/h pulverized coal boiler. Results show that the deep air staging with 30% separated over fire air (SOFA) creates a high temperature and strong reducing atmosphere in the reducing zone ...
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Lowrank coal (calorific value below 5,100 kcal/kg) and mediumrank coal (5,1006,100 kcal/kg) dominate current Indonesian coal production. Coal reserves are estimated to be about % for lowrank coal and around % for mediumrank coal. The country's power plants use both types of coal as fuel. Basically, coal calorific value is one ...
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Two coals, bituminous (American Baily Pittsburgh No. 6) used in Israeli utilities and lignite (brown coal Hambach) used in German power plants, have been investigated in this study. The results show that the combined TG/DSC method can provide a much better understanding of the chemical reactivity of coals in the combustion process.
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In this study, a method for insitu determination of the coal calorific value was developed based on a flow calorimeter. The temperatures of gas and walls and energy distributions in the calorimeter at gas flow rates of 0 1, 0. 5, 1. 5 and 3 m 3 / h, coal mass of 0. 5, 1, 1. 5 and 2 g and wall thickness of 1, 10, 25 and 50 mm were numerically ...
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The calorific value of coal mainly depends on the content of combustible organic elements and ash, and is a comprehensive indicator of coal quality. It is of great significance to quickly obtain the calorific value of coal entering the boiler for the optimal control of coal blending and combustion in thermal power generation. However, the measurement repeatability of LIBS for the coal ...
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Pulverized coal absorbs part of the heat to increase its own internal energy, enhancing the char performance and accelerating the achievement of the volatile matter combustion temperature; furthermore, the calorific value needed to reach the ignition temperature is guaranteed. 51 In the pyrolysis stage, WOS has a dominant effect on pulverized ...
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The combustion efficiency of a coal is often measured in terms of burnout. In this study, the ash tracer method [21], [22] was adopted to determine the burnout of the tested coals. The burnout can be expressed as (1) Burnout (%) = A s h u c − A s h r c A s h u c (1 − A s h r c 100) × 100 where Ash uc and Ash rc stand for ash contents in the unburned char and the raw coal, respectively.
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Meanwhile, the combustion of pulverized coal is a process, involving coupled effects among fluid mechanics, heat and mass transfer, and chemical kinetics. That is to say, the components and calorific values of combustible mass released from the fuels at different stage of combustion process are varied greatly.
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Though several factors affect the calorific value, including the type of coal, particle size, and environmental conditions [2530]. The scope of this work is limited to explore the effect of environmental factors (temperature, humidity, and air flow) on low grade coal pulverized to obtain average particle size of 213 μm, according to ...
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The pulverized coal preheatingcombustion test platform for peak shaving (Fig. 1) consists of a PreCFB, a combustion chamber and auxiliary design load of the test platform is 1 MW, the primary air with a low air equivalence ratio carries the pulverized coal particles into the PreCFB for gasification and partial combustion, generating hightemperature preheated fuel.
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The interaction between the optical thickness and the radiation pulsation of pulverized coal particles during the combustion process is studied to learn the influences of turbulent particle combustion on radiative heat transfer.
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With the slagging index (R S) when the test coal ash mass ratio for C 1 /C 2 is 1:1, comparable values can be obtained for a mixture of coal ashes with biomass B 1 ash additions in the ratio of C 1 /C 2 /B 1 —15:70:15 (Fig. 3b), for which the amount of fuel directed to the comass ratio (of raw dry fuels) was 7:37:56 m/m.
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According to the peak shape of the DTG and DSC curves, the combustion process of pulverized coal can be divided into two stages: (1) The volatile escaping and homogeneous combustion stage (260410 °C); the organic components in coal undergo a small amount of easytobreak small molecular sidechain pyrolysis at about 320 °C, perform a fast ...
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Considering an injection rate of 100 kg/t of pig iron, when a coal with a calorific value of 7500 kcal/kg is replaced by another one with 7700 kcal/kg, the fuel rate change is 4 kg/t of pig iron ...
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Fig. 4 shows the volume fractions of these gases mentioned above and the net calorific value (CV, MJ/Nm 3) of the preheated coal gas. The calorific value of CO is higher than those of CH 4 and H 2, and more CO is generated in O 2 /CO 2. Therefore, the net calorific value of the preheated coal gas in O 2 /CO 2 is higher than that in air. In air ...
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Calorific value. Calorific value, measured in British thermal units or megajoules per kilogram, is the amount of chemical energy stored in a coal that is released as thermal energy upon combustion. It is directly related to rank; in fact, the ASTM method uses calorific value to classify coals at or below the rank of highvolatile bituminous (above that rank, coals are classified by fixed ...
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The Chinese national standard GB/T [7] exhibits the experimental specification for coal calorific measurement using the bomb calorimeter. However, the bomb calorimeter has a complex structure, cumbersome operation, and has a large measurement hysteresis, which makes it impossible to obtain the realtime calorific value of coal.
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The time required for the LIBS measurement process (see Table 1) depends on the frequency and number of scans. In this study, the frequency and number of scans are set to 4 spectra per second and 196 spectra per sample, respectively, resulting in 49 s for LIBS measurement. ... Improved measurement of the calorific value of pulverized coal ...
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A commentary has been published: Discussion: "PulverizedCoal Firing of Marine WaterTube Boilers: Following Upon an Appreciation of the Results Secured in the Stationary PowerPlant Field With Pulverized Coal, a Series of Tests Were Conducted to Determine the Value of This Method of Firing to Marine Boilers" (Stillman, T. B., 1928, Trans. ASME, 4950(3), p. 031066)
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error (ARE), and the standard deviation (SD) of this method for predicting the calori c value of coal are fi MJ kg−1, % and MJ kg−1 respectively. The measurement repeatability...
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The realtime quantitative analysis of the calorific value of pulverized coal particle flow is important for the efficient and clean combustion of coal. Herein, a piezoelectric vibratory feeder produced a continuous flow of pulverized coal particles, which were detected by laserinduced breakdown spectroscop
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The average measurement errors for carbon, hydrogen, volatile, ash, heat values is %, %, %, % and .07MJ/kg, respectively, and all of these measurement accuracies have totally ...
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Densephase pneumatic conveying of pulverized coal experiments with superficial gas velocity ranged from m s −1 to m s −1 were carried out on the selfestablished 50 mm industrial pipe facility. The fluctuations of pressure, solid velocity, solid concentration and the average crosssection concentration were analyzed in terms of relative standard deviation (RSD), powder ...
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The heating value (or energy value or calorific value) of a substance, usually a fuel or food (see food energy), is the amount of heat released during the combustion of a specified amount of it.. The calorific value is the total energy released as heat when a substance undergoes complete combustion with oxygen under standard chemical reaction is typically a hydrocarbon or other ...
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The pulverized coal was dried at three selected temperatures of 25 °C, 75 °C and 110 °C, and the moisture and porosity of the pulverized coal particles were measured. Based on the porosity range obtained from the measurement, 3D steady numerical simulation of combustion in tangentially coalfired furnace was conducted by use of Fluent Software.
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As a result, the values from this study were smaller by % for the calibration line and by % for the validation line in nearinfrared spectroscopy. The RMSE average values for calorific values were calculated to be less than 1%. Keywords: laserinduced breakdown spectroscopy (LIBS); coal; sulfur; calorific value; multivariate data ...
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34 Gudimella Tirumala Srinivas et al.: Efficiency of a Coal Fired Boiler in a Typical Thermal Power Plant s [( ) ( )]2 1 4 3 100 f f w h h h h w GCV × − + − = × × (3) Here GCV f is the gross calorific value of the coal (kJ/kg), whose measurement is based on mass of coal for which hoppers are mounted over the boilers on calibrated load cells [15].
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