The grinding method of fossil coal fuel

 

(57) Abstract:

The invention relates to the production technology pulverized coal fuel for flaring. The grinding method of fossil coal fuel for flare combustion in thermal power plants based on power effect on the milled material. Force is microwave electromagnetic field, specific absorption rate, which is chosen from the condition R = Cp(T1-T2)/t, where Cp- specific heat of coal, T1his initial temperature, T2125C, and the time of heating coal from T1to T2is t1.5 C. Experimental studies of the proposed method showed that the dispersion of carbon occurs when the microwave temperatures up to 125C, and the characteristic size of the coal grains is 10 to 20 μm.

The invention relates to the production technology pulverized coal fuel for flare combustion in thermal power plants.

In the production of pulverized coal fuel for flare combustion in boilers use such operations as a force on the pieces of crushed material and udot ash and sulfur impurities, where a force on the processed coal is a complex physical and chemical processes for producing coal dust with a characteristic grain size of 6-10 microns and the content of the ash impurities less than 1% by weight (P. L. Flunn, B. D. Hsu, G. L. Leonard. Coal Fueled Engine Progress at GE Transportation System. Journal of Candy for Gas Turbines and Power. July 1990, v.112, p.369-375). The disadvantages of this method include its high cost, multiple and complexity of the use of technological equipment.

The closest to the technological nature of a grinding method of fossil coal fuel [Chechetkin A. C., Anemones N. A. Thermal engineering. - M.: Higher school, 1986, S. 344], in which the grinding mnogozalny coals carried out using ball mills in which the grinding conduct of cast iron or cast basalt balls poured into the drum, rotating at 20 rpm Separation of coal dust in size and partly on the composition of the grains here is stand alone installations of gravity-vortex type. The disadvantages of this method are the lower bounds of the average particle size of the comminuted coal, equal to 40 μm, and the impossibility of subsequent separation of the ash and primany the tion, is the reduction of the characteristic size of the coal particles and the simultaneous separation of the ash constituents of the coal from its combustible bases in the area of grinding.

The essence of the proposed method lies in the fact that for grinding fossil coal fuel a force on the material by the microwave electromagnetic field, specific absorption capacity [W/kg] is chosen from the condition P=Cp(T2-T1)/t, where Cp- specific heat of coal, T1his initial temperature, T2125C, and the heating time t temperature T1to a temperature T2is t1,5 C.

Microwave power is actively absorbed by the charcoal evenly over the volume of the processed pieces of type “walnut”-“the seed”. Coal is a moisture-containing (H2About = 10-12% by weight) imperfect dielectric with a dielectric constant of 3.8; tg0,05, and absorbed microwave power can heat it to a temperature at which the vapor pressure of water contained in the pores of the coal, is sufficient to sever the links between the coal particles. The pressure and temperature of saturated water vapor connected by the relation , where the subscript “1” refers to the initial state pavement unit of work (1/4270 [Kcal/(Nm)]) and the gas constant of water vapor. If we take T1=372,1, when the saturated vapor pressure p1=1.0 ATM, the interval K T2405,9 To 1.0 ATM p23 ATM permanent . Specific absorbed microwave power, necessary for the destruction of the coal by the saturated vapor pressure is determined by the ratio P=Cp(T2-T1)/t, where, in turn,

is determined by the bursting pressure p2and WITHp=1260 j/(kgK) specific heat capacity of coal type anthracite”. Time t heating the coal to a temperature T2where does the process of destruction of the coal into fine particles, determined experimentally, as in the literature, no data are available. The finiteness of time heating the coal to a temperature of destruction of T2associated with the natural leakage of its pores, leading to leakage of water vapor formed.

To validate the proposed method performed experiments on the atomization of coal rubble with the amount of pieces of 1.5-2.0 cm3in a cylindrical resonator E010type by volume of 500 cm3powered by a magnetron power of 600 W at a frequency of 2450 MHz. Received coal dust were subjected to microscopic examination.

The results eksperimentov occurs when they are heated to 125C (C), which corresponds to the vapour pressure of water of 2.4 ATM (2,4105PA), and the time of heating to the specified temperature not greater than 1.5 C. the Characteristic size of the coal grains ranged from 10 to 20 μm, the reduction of the characteristic size of the particles corresponds to the reduction of time of heating the coal sample to 1 C. it is essential that dust particles containing ash admixture of coal are in the microwave grinding of much greater dimensions (4050 μm) and were separated from combustible dust basics cyclone way directly into the working chamber of the microwave spray.

Thus, computational and experimental studies of the proposed method of fine grinding of coal confirmed the possibility of obtaining dust grains with a typical size of 10 μm, which is substantially less than the grain size obtained using the prototype method, as well as the possibility of separating ash impurities with the help of air flow, blowing a comminuted material, directly in the area of grinding.

In industrial installations for the production of pulverized coal to power the cavity of the working chamber, it is expedient to use a standard microwave generator with a capacity of 50 kW at a frequency of 915 MgO 125C not less than 0.3 kg/s or 1.1 t/h, which is enough to power a powerful boiler installation with jet fuel combustion.

The grinding method of fossil coal fuel, which consists in the power effect on the milled material, characterized in that a force on the material is carried out of microwave (MW) electromagnetic field, specific absorption rate, which is P [W/kg] is chosen from the condition R = Cp(T1-T2)/t, where Cp- specific heat of coal, T1his initial temperature, T2125C, and the heating temperature T1to a temperature T2is t 1,5 C.

 

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FIELD: disintegration of hard materials, production of finely divided systems and emulsions.

SUBSTANCE: apparatus includes housing with inlet and outlet branch pipes and arranged in cavity of housing oscillation concentrator in the form of pack of pates secured to housing by means of pins. Outer plates are fastened to both ends with possibility of creating forming profile by means of regulating members. Inner plates are fastened at one end and they are mounted in such a way that their free ends may freely enter one behind another at forming slits between them. Regulating members may be in the form of bolts passed through nuts. The last are rigidly secured to housing that may have rectangular or square cross section.

EFFECT: enhanced efficiency of process for preparing suspensions and finely divided powders.

5 cl, 2 dwg

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