SU1249427A1 - Device for determining carbon in carry-over ash of pulverized-coal fired boiler units - Google Patents

Abstract

The invention relates to a measurement technique for investigating the properties of bulk materials by measuring the electrical capacitance of a sampled sample. The purpose of the invention is to improve the accuracy of the determination. The device contains a capacitive sensor in the form of a vertical tube with a variable cross-section with electrodes connected to a capacitor-electrical signal converter. A table fixed with a gap at the lower end of the tube, vibrators and accelerometers: fixed rigidly on the tube computing unit. 1 il. I (Lgo 4 SO .4 Yu

Description

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The invention relates to a measurement technique, in particular to the study of the properties of volatile materials by measuring the electrical capacitance of a sampled sample, and can be used in mining equipment, engineering, building materials, in power engineering to control the carbon content in volatile ash.

The purpose of the invention is to increase the accuracy of determination.

The drawing shows schematically a device for determining coal of a kind in the fly ash of pulverized coal fired units.

The device consists of a capacitive sensor in the form of a vertically mounted dielectric tube 1, for example glass, with overhead electrodes 2 and 3 in its lower part connected through a converter 4 capacitance type electric signal to the input of the control computer 5, narrowed to the base, and an additional electrode 6 of the ash flow measurement unit, located at the upper base of the tube and connected through an additional capacitance converter 7 - electric signal to the input of the computing unit 5, 8, fixed with a gap h at the lower base of tube 1, vibrators 9 and 10, rigidly fixed on tube I and column 8 and connected to the output of the computing unit 5, indicator II connected at the output of the computing unit 5, and accelerometers 12 and 13, mounted on the tube 1 and the table 8 in the compartment from the vibrators and connected via the analog-digital converter 14 to the input of the computing unit 5,

The device works as follows.

Ash is loaded into tube 1 and vibrated with vibrators 9 and 10, having reached the vibro-fluid state of minimum viscosity (dynamic viscosity 3 N / s), while simultaneously passing it through the gap with a flow satisfying the ratio

, 5 G / S-f) ,, (1)

where h is the size of the gap tube and table, mm; G 7 ash consumption, kg / s;

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S - tube section, m; f is the frequency of the vibrators, Hz; 0.5 is the experimental coefficient depending on the dispersion of the ash bone.

The device operates in a mode that satisfies the ratio (O monitors the sensor ash flow measurement unit, consisting of an additional electrode 6 connected through an additional converter 7 to the computing unit 5. The metering unit for the memory used by the computing unit

The program evaluates the speed of the ash at its minimum viscosity based on the height of the ash level. sensor above the table, pre-scaled depending

20 from the consumption of ash. The height of the level at etrm is determined by the capacitance of the electrode 6, proportional to the column of ash in the sensor, and its dielectric constant, determined by

25 according to the capacitance between the electrodes 2 and 3, the value of which through the transducer 4 in the form of an electrical signal enters the computing unit 5. According to the received information, the calculating unit 5 changes the operation mode of the vibrators 9 and 10, maintaining the G / f ratio unchanged (1 ), and simultaneously on the increment of the capacitance between the electrodes 2 and 3 relative to the capacitance of the sensor filled with: carbon-free ashes 5, and the calibration graph relating the weight content of carbon in the ashes with increment of capacitance, calculates the concentration carbon in ash and transmits data to indicator 11,

The ash vibro-liquefaction is controlled by accelerometers 12 and 13, the electrical signals of which are minimal when the ash in the capacitive sensor has minimal viscosity. Accelerometer signals through analog-to-digital converter 14 are fed to the computing unit 5, which

JQ continuously adjusts the frequency of the vibrators 9 and 10, changing the mode of their thyristor power sources to the direction of decreasing the signals of accelerometers.

The tuning of the modes of the vibrators 9 and 55 10 is carried out with the computing unit 5 turned off, alternately changing their frequency and obtaining the minimum signals from the accelerometers 12 and 13.

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Then connect the control computing unit.

A feature of the proposed device is the use of

(The process of measuring all the ash that entered the ash collector from the boiler unit duct. Therefore, the ash consumption fluctuates with changes in the combustion mode of the furnace and coal quality, and in a capacitive sensor of a cylindrical type, level fluctuations are difficult to compensate only by changing the frequency of the vibrators. Level fluctuations with significant deviations of the flow rate from the average value in the proposed device, the tube 1 of the capacitive sensor carries a variable cross section with a large base in the upper part. that the tube is not

there should be sharp kinks that cause local intense vibrations that violate the uniformity of vibro-ash in the entire volume of the sensor; This condition is satisfied, for example, by exponential and conical tubes. The ratio of the base areas of such a tube, chosen to be equal to the relative deviation of the flow rate, ensures that the level fluctuates within 33% of the average,

that dp is enough reliable operation of the automatic system of the device. For example, with daily fluctuations of 15% of the average consumption (the ratio of maximum to minimum consumption of 1.35), the level of ash is 11.5%. In addition, the implementation of a tube with inclined walls with a ratio of upper and lower bases selected from the suspension increases the effect of the transfer of the oscillation energy of the walls by ash particles due to the appearance of oscillations of the inclined walls and

. it makes it possible to reduce the oscillations of the walls of the sensor tube in comparison with the known cylindrical version of the tube. However, it is not necessary to increase the ratio of base diameters more than what follows from the condition, because it is difficult to achieve equal to the measured vibro-liquefaction in the entire volume of the sensor.

A device for determining carbon is plugged into a system for transporting ash collected from gas

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yes dl: gravimetric analysis. Filling the tube I, turn on the vibrator 9. Change the power of the engine, obtain the minimum reading of the accelerometer-5. Then connect the vibrator 10 and achieve the minimum reading from the accelerometer 13. Check the tuning of the vibrator 9 and connect the power sources of the vibrators to the control from the computing unit five.

When ash is moving through a capacitive sensor, its capacity varies between electrodes 2 and 3 depending on the carbon content of the ash, and on electrode 6, moreover, on the level of ash in the capacitive sensor. Indicator 1I, corresponding to the absence of carbon in the ash, is taken as the zero reference level. By incrementing the indicator readings in. The measurement of carbon and the calibration graph, which was previously constructed from ash samples with a known concentration of carbon, determine the relative carbon content in the ash. The obtained capacitance value between the electrodes 2 and 3, proportional to the effective relative dielectric constant 0 of the ash, is transferred to the calibration curve capacitance - ash level constructed for electrode 6 depending on the possible values of the effective permittivity 2-5 or, equivalently, the capacitance of the electrodes 2 and 3. Knowing from the preliminary measurements (or calculation), the law relating to the flow rate with the level of ash in the Q capacitive sensor changes the frequency of the vibrators towards inequality (1),

The proposed device for determining carbon segregation in fly ash of dust-burning coal-fired boilers by eliminating ash dumping at the input of a capacitive sensor and controlling the mode of vibrating ash particles depending on the ash level in it through a computing unit, as well as reducing the level of level fluctuations in a variable cross section tube, the accuracy of 5 measurements can be traced. In addition, knowing the consumption of ash through a capacitive sensor, it is possible to estimate roughly the total flow of ash in the flue of the boiler unit.

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Claims (1)

Formula Eteni A device for determining carbon in the fly ash of pulverized boiler units containing a capacitive sensor in the form of a vertical tube with electrodes connected to a capacitance-electric signal type converter, and a table fixed with a gap at the bottom of the tube, vibrators and Accelerometers fixed rigidly on the tube and table, the computing unit, to the input of which the transducer and accelerometers are connected, and the output is connected to the vibrators and the indicator, characterized in that, in order to improve the determination accuracy, it it is equipped with a unit for measuring 1 ash ash, filled in the form of an additional electrode, placed at the upper base of the tube and connected via an additional capacitance type converter - an electrical signal to the input of the computing unit, and the tube of the capacitive sensor is made with a variable cross section with the ratio of the diameters of the upper and lower bases selected from the conditions  D / d -D D is the diameter of the upper base of the tube; d - diameter of the lower base tubes to - the ratio of the maximum and minimum ash cost. 12 10 Compiled by A.Platova Editor E.Papp Tehred G.Gerber CorrectorM.Maksimishinets Order 4229/45 Circulation 778 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, st. Project, 4