KR200340748Y1 - Apparatus for measuring coal suppling state of coal fired thermal power plant boiler - Google Patents

Abstract

The present invention relates to an apparatus for measuring coal supply status of a coal-fired power plant, and detects static electricity of coal powder in a conduit in which coal powder is supplied from a mill to a boiler, thereby measuring the supply state of coal powder quantitatively and accurately.

Description

Apparatus for measuring coal suppling state of coal fired thermal power plant boiler}

The present invention relates to an apparatus for measuring coal supply status of a coal-fired power plant, and more particularly, to an apparatus for measuring coal supply status of a coal-fired power plant capable of quantitatively measuring the state of coal powder supplied to a boiler.

In general, coal-fired power plants are roughly classified into coal-fired power plants and oil-fired power plants according to the type of fuel used. In coal-fired power plants, finely powdered or pulverized coal is pulverized in a pulverizer. It supplies through the conduit and mixes the supplied coal powder with air in the damper at the set ratio and inputs it into the furnace of the boiler to burn it, increasing the water in the water pipe, The steam is generated by rotating the turbine (SteamTurbine).

In the combustion control system of the coal-fired power plant as described above, as shown in FIG. 1, when a manager or an upper control apparatus inputs a control command according to a target fire power, the main control unit 1 controls a control value such as an air-fuel ratio. Calculation and outputting it, and according to the control value output from the main control computer 1, the local control unit 2 controls the respective dampers (D1 ~ D4) of the boiler (B) and injected into the boiler (B); It is made to adjust the mixing ratio of air, that is, air-fuel ratio.

In the coal-fired power plant as described above, since the main raw material is coal powder, the thermal power in the boiler may vary depending on the state of coal powder supplied from the mill to the boiler.

However, since the coal powder moves through the conduit, it was not possible to quantitatively measure the coal powder supply state in the conduit conventionally, and thus, when the coal powder is in poor condition, the thermal power may not be accurately controlled to the target value. There was a problem that requires a lot of manpower and time to correct this.

The present invention has been made to solve the problems of the prior art as described above, the coal supply state of the coal-fired power plant that can quantitatively accurately measure the supply state of the coal powder which is micronized from the differentiator and supplied to the boiler through a conduit The purpose is to provide a measuring device.

1 is a schematic diagram of a combustion control system of a conventional general coal-fired power plant,

2 is a schematic diagram of an optimal combustion control system of a coal-fired power plant according to a preferred embodiment of the present invention,

(A) and (b) of FIG. 3 are plan and side views showing the structures of the first and second detection units shown in FIG.

4 is a schematic structural diagram of a probe shown in FIG. 3;

FIG. 5 is a view showing a state in which a first detection unit and a second detection unit shown in FIG. 3 are installed in a conduit; FIG.

6 is a cross-sectional view taken along the line “AA” of FIG. 5;

7 (a) and 7 (b) are a plan view and a side view showing the structure of the third detection unit shown in FIG.

FIG. 8 is a view showing a state in which a third detection unit shown in FIG. 7 is installed in a conduit; FIG.

9 is a sectional view taken along the "BB" direction in FIG. 8;

10 is a view for explaining the principle of charging static electricity in coal powder particles,

11 is a view for explaining the action of detecting the static electricity of coal powder particles,

12 is a view for explaining the action of detecting the static electricity of coal powder particles through a probe and converting it into a current signal,

FIG. 13 is a graph showing signal waveforms of alternating current against static electricity detected through probes of the first to third detection units; FIG.

14 is a spectrum of a signal waveform obtained by converting an AC current into a DC voltage in FIG. 13;

15 is a view for explaining the principle of operation of the first detection unit;

16 is a view for explaining the principle of operation of the second detection unit;

17 is a view for explaining the operation principle of the third detection unit.

<Explanation of symbols for the main parts of the drawings>

10: first detector 20: second detector

30: third detection unit 40: measurement / analysis control unit

50: arithmetic processing control unit 60: local control unit

70: terminal 110, 210: clip

120, 170, 220: probe 121: rod

122: fixing member 123: case

130, 230: signal line 140, 240: protective cover

150, 151, 160, 250, 260: hoses 161, 261: connecting pipe

162, 262: cable duct P: differentiation

B: Boiler D1 ~ D4: Damper

C: coal feed conduit

In order to achieve the above object, a coal supply state measuring apparatus of a coal-fired power plant according to a preferred embodiment of the present invention is mixed with finely divided coal powder supplied from a pulverizer and supplied through a conduit at a predetermined ratio with air through a damper and input to a boiler. In a coal-fired power plant, which is combusted, it is installed at a specific point inside the conduit to detect static electricity of coal powder particles, and is installed inside a conduit at a point separated from the detection part by a set distance in the longitudinal direction of the conduit. And a control means for comparing the electrostatic waveforms of the respective detectors to obtain a time difference between the electrostatic waveforms corresponding to each other, and calculating and outputting the coal dust moving speed in the conduit through comparing the electrostatic waveforms of the respective detectors. It is done.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a schematic diagram of an optimal combustion control system of a coal-fired power plant according to a preferred embodiment of the present invention, as can be seen with reference to the same drawing, the optimal combustion control system of a coal-fired power plant according to the present invention, the first detection unit 10, the second detection unit 20, the third detection unit 30, the measurement / analysis control unit 40, the operation processing control unit 50, the local control unit 60, and the terminal 70.

The first detection unit 10 is installed at a specific point inside the conduit (C) for supplying the coal powder from the fine powder (P) to the boiler (B) to detect the static electricity of the coal powder particles in a plurality of places in the transverse direction If the number of conduits C is plural, it may be installed in any one of them, but in order to improve the accuracy of the measurement, it is preferable to install all in each conduit C.

The second detection unit 20 is installed in the conduit (C) at a point closer to the boiler (B) side by a set distance in the longitudinal direction of the conduit from the first detection unit 10 to prevent static electricity of coal powder particles. In order to detect, as in the first detection unit 10, if the number of conduits (C) is a plurality of them may be installed in any one of them, in order to improve the accuracy of the measurement is to install all in each conduit (C) desirable.

Since the first detection unit 10 and the second detection unit 20 are installed in close proximity to each other, it is preferable that the first detection unit 10 and the second detection unit 20 are installed together in the conduit C using one coupling means.

Thus, in the present invention, the structure of the first detection unit 10 and the second detection unit 20 formed integrally will be described with reference to FIGS. 3 to 6.

Among the integrated first and second detection units 10 and 20, the first detection unit 10 can be bent as a wide flat plate and bent as shown in FIGS. 3A and 3B. Clip 110 and a plurality of probes (120) which is fixed to penetrate both ends of the clip 110 and the nut (112) through the clip 110 in the state, And a signal line 130 connected to the measurement / analysis control unit 40 from each probe 120.

However, each probe 120 is disposed so as to be spaced apart from each other by a predetermined angle (for example, about 120 °) in the conduit (C).

Here, a plurality of protective covers 140 are fixedly installed on the upper portion of the clip 110 to protect the plurality of probes 120, and a flexible hose is drawn out between the protective covers 140 to draw out the signal lines 130. (flexible hoses) 150 and 151 are installed therethrough, and the signal line 130 drawn out from each probe 120 is connected to the flexible hose 160 and the connection pipe 161 and the cable duct from one of the protective covers 140. It is configured to be connected to the measurement / analysis control unit 40 through 162.

The second detection unit 20, like the first detection unit 10, has a plurality of probes 170 fixed through the clip 110 and from the plurality of probes 170 to the measurement / analysis control unit 40. Including a signal line 180 to be connected, the plurality of probes 170 are each disposed in a proximal position spaced apart from the probe 120 of the first detection unit 20 by a predetermined distance.

Here, the probe 170 of the second detector 20 is protected by the protective cover 140 together with the probe 170 of the first detector 10, and the signal line 180 of the second detector 20 is formed of 1 is configured to be connected to the measurement / analysis control unit 40 through the flexible hose 160, the connection pipe 161, and the cable duct 162 together with the signal line 130 of the detection unit 10.

As illustrated in FIG. 4, the probe 120 of the first detection unit 10 may include a rod 121 made of a conductor (for example, tungsten carbide) and a nonconductor (for example, nylon material). Made of a pipe-like fixing member 122 for fixing the upper end of the rod 121 to the clip 110 and the conduit C, and a flexible material (eg, silicon) to fix and protect the signal line drawn out from the upper end of the rod 121. It is composed of a case 123 made of a rubber material).

The probe 170 of the second detector 20 also has the same configuration as the probe 120 of the first detector 10.

The first and second detectors 10 and 20 configured as described above have insertion holes H for inserting the probes 120 and 170 into the conduit C to be installed, as shown in FIGS. 5 and 6. ) And bend the clip 110 to surround the outer circumferential surface of the conduit (C), insert each probe (120, 170) into the insertion hole (H) of the conduit (C) and insert it into the conduit (C). , And is fixed by fastening both ends of the clip 110 by using the bolt 111 and the nut 112.

Next, the third detection unit 30 is installed in the bent portion of the conduit C, and the static electricity of the coal powder particles at the first point having a small bending radius and the second point having a large bending radius, respectively. For the purpose of detecting the number of conduits (C) may be installed in any one of the plurality, but in order to improve the accuracy of the measurement, it is preferable to install all in each conduit (C).

As shown in FIGS. 7A and 7B, the third detection unit 30 may be bent as a wide flat plate and may be connected to both ends of the bolt 211 and the nut 212 in a bent state. Clip 210 made of a structure that can be fastened with a pair, a pair of probes (220) fixed through the clip 210, and connected from each probe 220 to the measurement / analysis control unit 40 The signal line 230 is included.

However, one pair of probes 220 may be located at a first point having a small bending radius inside the conduit C and at a second point having a large bending radius inside the conduit C. Is placed.

Here, a pair of protective covers 240 are fixedly installed on the upper portion of the clip 210 to protect the pair of probes 220, and a flexible hose to draw out the signal line 230 between each protective cover 240 to protect them. (flexible hose) 250 is installed through, and the signal line 230 drawn from each probe 220 is the flexible hose 260 and the connection pipe 261 and the cable duct 262 from any one of the protective cover 240 It is configured to be connected to the measurement / analysis control unit 40 through).

Here, the probe 220 of the second detector 30 has the same configuration as the probe 120 of the first detector 10.

As illustrated in FIGS. 8 and 9, the third detection unit 30 configured as described above drills the insertion hole H for inserting the probe 220 into the bent portion of the conduit C to be installed. After bending the clip 210 to surround the outer circumferential surface of the curved conduit C, each probe 220 is inserted into the insertion hole H of the conduit C, and then inserted into the conduit C, and then the clip 210. Both ends of the bolt 211 and the nut 212 are fastened by fastening.

The measurement / analysis control unit 40 directs static electricity measured by the first detection unit 10, the second detection unit 20, and the third detection unit 30 by a control command input from an administrator or a higher control device. After converting to voltage, it is input again by A / D conversion (Analog To Digital Convert).

In addition, the measurement / analysis control unit 40 calculates a distribution of coal flow in the conduit C according to a ratio between the static electricity values of a plurality of places in the conduit C measured by the first detection unit 10. In addition, by comparing the electrostatic waveforms measured by the first detection unit 10 and the second detection unit 20 to calculate the time difference between the electrostatic waveforms coincident with each other, and calculates the velocity of coal dust in the conduit (C) through this. .

In addition, the measurement / analysis control part 40 is based on the static electricity value calculated | required at the 1st point with a small bending radius and the 2nd point with a large bending radius inside the curved conduit C by which the 3rd detection part 30 is measured, respectively. The concentration of coal powder at the first and second points is calculated, and the particle size of coal is calculated by the ratio of the concentration of coal powder at the first and second points.

In addition, the measurement / analysis control unit 40 includes control commands inputted from a manager or a higher control device, calculated a) coal flow distribution in the conduit C, and b) coal powder moving speed in the conduit C. And c) the particle size of the coal powder is transferred to the operation processing control unit 50.

The arithmetic processing control section 50 is a control command received from the measurement / analysis control section 40, a) coal powder flow distribution in the conduit (C), b) coal powder moving speed in the conduit (C) and c) coal powder Calculate and output the control value to generate fire power of the target value by performing calculation according to the particle size of.

In addition, the arithmetic processing control unit 50 performs calculation according to a) coal powder flow distribution in conduit C, b) coal powder moving speed in conduit C and c) particle size of coal powder. The fineness of the coal powder by the differentiator P is controlled by determining the fineness of and calculating the control value accordingly and transmitting it to the differentiator P.

The local control unit 60 controls the respective dampers D1 to D4 of the boiler B according to the control value output from the arithmetic processing control unit 50, that is, a mixing ratio of coal powder and air introduced into the boiler B, that is, Adjust the air-fuel ratio.

The terminal 70 is a control value for generating the coal dust flow distribution in the conduit (C), the movement speed of the coal powder in the conduit (C), the particle size of the coal powder, and the thermal power of the target value. Mark it for monitoring.

Hereinafter, with reference to the accompanying drawings for the effect of the present invention configured as described above will be described in detail.

First, the principle of detecting the static electricity value for the coal dust in the conduit C through the probes 120, 170 and 220 of the first detector 10, the second detector 20 and the third detector 30, respectively. The following is the description.

When two or more pieces of material collide with each other, they are each charged with static electricity. This phenomenon is called "Triboelectrification", and the filling caused by the contact of particles moving through air into conduits such as pipes or ducts is mainly due to the following 1) to 3). It depends on the variable.

1) Chemical Properties of Particles

2) speed of particles

3) particle size and shape

As illustrated in FIG. 10, when the particles Pt collide with the steel material wall Cw of the conduit, the particles Pt are charged with static electricity. On the other hand, the wall Cw of the conduit is also charged with static electricity, where the static electricity charged in the conduit wall Cw has the opposite polarity to the particles.

If the conduit is grounded, the static electricity will escape to the ground, but if the conductor CT as shown in Fig. 11 is in close proximity to the conduit wall Cw filled with static electricity, the conductor Mirror static electricity of opposite polarity is generated on the surface of the CT.

The present invention uses this phenomenon, the coal particles in the conduit (C) is charged with static electricity while hitting the wall in the conduit (C), as shown in Figure 12, the probe 120 made of a conductor ( When installed in C), mirror static electricity is generated on the surface of the rod 121 of the probe 120.

As the static electricity generated on the surface of the rod 121 of the probe 120 moves through the signal line 130, an electric current is generated, and the generated current is input to the measurement / analysis control unit 40 through the signal line 130. do.

At this time, the current input from the signal line 130 to the measurement / analysis control unit 40 represents an alternating current waveform as illustrated in FIG. 13 as a raw analog signal.

The current of the input AC waveform is converted into the DC voltage as illustrated in FIG. 14 by the measurement / analysis control unit 40 and then A through the A / D converter built in the measurement / analysis control unit 40. / D is converted into a digital signal that can be recognized by the computer.

Next, the operation of measuring the coal powder flow distribution in the conduit C through the first detection unit 10 is as follows.

When the pulverized coal dust is moved by pneumatically into the conduit C, a roping phenomenon of the coal dust may occur. Since the probe 120 detects only a close signal, the roping phenomenon may appear as a result of weakening of the signal when the distance from the probe 120 increases.

In order to solve the instability of the signal detection caused by the roping phenomenon, as illustrated in FIG. 15, the first detection unit 10 includes a plurality of probes 120 (eg, about three) inside the conduit C. Is disposed at a constant angle (eg, about 120 °) and connects each probe 120 through the signal line 130.

The coal dust flow distribution REF in the conduit C is calculated by the DC voltage value converted by the measurement / analysis control unit 40 as described above, and is defined as in Equation 1 below.

In the measurement / analysis control unit 40, the coal dust flow distribution in the conduit C is calculated as a percentage by the formula defined by Equation 2 below, but is calculated for each conduit C, respectively. do.

In Equation 2, h is the number of conduits (C) connected from the differentiator (P) to the burner (B), and the parameters k and n are the coal flows obtained by sampling the physical coal flow. It is a balance value.

Next, the operation of measuring the coal powder flow rate in the conduit (C) through the first detection unit 10 and the second detection unit 20 will be described.

Basically, as shown in FIG. 16, the measurement / analysis control part 40 arrange | positions the 1st detection part 10 and the 2nd detection part 20 by the fixed distance S (for example, about 50 mm). In addition, by comparing the electrostatic waveforms measured by the first detection unit 10 and the second detection unit 20 to obtain a time difference between the electrostatic waveforms coincident with each other, thereby calculating the coal dust moving speed in the conduit (C). .

That is, when a bundle of coal powder particles passes through the probes 120 and 170 of the first detector 10 and the second detector 20, a signal is formed at each probe 120 and 170. Since there is a difference in distance S between the probe 120 of the detector 10 and the probe 170 of the second detector 20, the probes 120 and 170 of the first detector 10 and the second detector 20 are different. There is a phase lag between signals resulting from

Therefore, since the distance S between the probe 120 of the first detector 10 and the probe 170 of the second detector 20 is known, the velocity of coal dust particles is determined by the probe of the first detector 10 ( The distance S between the 120 and the probe 170 of the second detector 20 may be calculated by dividing the distance S between the signals by the phase difference.

However, the flow of coal powder particles moving in the conduit C is rather complicated. Thus, the calculation is performed taking into account the phenomena associated with the coal powder particle flow, which will greatly affect the coal powder particle rate, as described below.

That is, coal particles moving with the gas stream are accelerated at a constant rate. This requires a force obtained from the kinetic energy of the gas flow. The velocity of the suspension is further reduced, assuming that more particles move in the gas stream and the fan power generating air pressure remains constant.

It is known that coal powder particles do not necessarily flow in a straight path in the z-axis direction when the longitudinal direction of the conduit C is in the z-axis direction. Coal dust particles also have kinetic components in the x and y directions due to gas streams and collisions between the particles.

The following are the main factors of the particle velocity change.

Gas velocity

Particle concentration

Particle size

-Collision frequency (also according to concentration)

There is also a slip between the coal dust particle rate and the gas velocity. Gas is faster than coal dust particles. It is observed that this slip is not constant, which depends on the coal particle size as well as the concentration of particles in the gas.

For example, the roping of heavy coal dust particles occurring in the ducts D1-D4 of the boiler B increases the local concentration of the particles and thereby increases the slip.

The slip as described above is defined by the factor K _s obtained between the coal powder particle velocity and the gas velocity, as shown in Equation 3 below.

In Equation 3, V _g is the velocity of gas and V _p is the velocity of particles.

Also to consider is that there are many collisions between particles as well as collisions with particles on walls or other flow paths on two phases of the gaseous stream where there is a high concentration of coal solids.

In particular, not all particles have the same velocity, and moreover, the velocity of coal particle bundles varies with function time.

That is, when the bundle of coal dust particles hits the probes 120 and 170, the velocity of the coal powder particles is reduced. At this time, if the measurement / analysis control unit 40 reads only the speed of the coal particles hitting the probes 120 and 170, it may show a speed that does not reflect the actual coal particle speed in the conduit (C). .

Accordingly, the measurement / analysis control unit 40 picks up the speed of the coal dust bundle once again after the first collision.

Further, in order to detect electrical items related to the velocity of coal particles flowing through the central portion of the conduit C, each probe 120, 170 of the first and second detectors 10, 20 is a conduit C. It is necessary to install deep enough inside.

For reference, the velocity of coal particles is always low and poorly measured near the conduit (C) wall.

Assuming that the coal particle particle velocity actually measured is within a range of about 10.0-40.0 m / s (30-133 ft / s), the probe 120 of the first detector 10 and the second detector 20 Assuming that the distance S between the probes 170 is about 50 mm, the coal dust particles move approximately between the probes 120 of the first detector 10 and the probes 170 of the second detector 20. It will take about 1.25-5ms.

In general, a short distance of 50 mm (2 inches) requires a high sampling rate and the spacing S between the precise probes 120 and 170 in order to measure high accuracy particle velocity.

Accurately matching the spacing S between the probes 120 and 170 using a predetermined jig that is relatively easy to use and suitable to achieve a high sampling rate to achieve acceptable speed measurement resolution. desirable.

In addition, as described above, the coal powder particles do not flow in a straight line in the z direction, and because of the roping and other phenomena, the coal powder particles also flow in the x and y directions, for example, the distance between the probes 120 and 170. If (S) is set at a relatively long distance of about 500 mm, a significant measurement error may occur due to the phenomenon that coal powder particles do not move in a straight line between the probes 120 and 170.

More specifically, assuming that the bundle of coal particles also has a movement in the y direction, the bundle is the probe 170 of the first detector 10 and the probe 170 of the second detector 20. Move an additional distance of approximately 38.5mm between the livers.

If the distance S between the probe 1200 of the first detector 10 and the probe 170 of the second detector 20 is a relatively long distance of about 500 mm, an error of about 8% is caused in the speed measurement. .

In contrast, when the distance S between the probes 120 and 170 is about 50 mm, the movement in the x and y directions causes no error in velocity measurement, but the movements in the x and y directions are adjacent to each other. Incoming probes cause in-phase signals.

Accordingly, the measurement / analysis control unit 40 has an algorithm that recognizes the in-phase signal as an error signal and removes the in-phase signal when calculating the speed.

Next, the operation of measuring the coal powder particle size in the conduit C through the third detection unit 30 will be described.

The principle of this measurement is based on the fact that larger particles than smaller particles have a smaller surface area for weight. Thus, when the large particles of coal dust pass through the curved portion of the conduit C, as shown in FIG. 17, they are concentrated at the second point R2 of the outer radius having a large bending radius. On the other hand, the small particles of coal dust stay at the first point R1 of the inner section when passing through the bent portion of the conduit C.

Accordingly, the measurement / analysis control unit 40 is configured such that the static electricity of the first point R1 having a small bending radius and the second point R2 having a large bending radius of the inside of the conduit C detected by the third detection unit 30 is large. The concentration of coal powder at the first point R1 and the second point R1 is determined by a value, and the coal concentration of the coal powder at the first point R1 and the second point R2 is obtained. Calculate the particle size.

The present invention is described by illustrating a specific embodiment, but the present invention is not limited to the above embodiment. Those skilled in the art can easily make various changes and modifications to the present invention, and it should be noted that such variations or modifications are included in the scope of the present invention as long as they use the features of the present invention.

In particular, in the above-described embodiment of the present invention, the case where all the first to third detectors are installed in order to quantitatively measure the supply state of coal powder, the coal powder flow distribution detected by the first detector is described. And the coal powder moving speed detected by the second detection unit and the coal powder particle size detected by the third detection unit can be selectively used as respective indices indicating the supply state of the coal powder.

That is, in the above-described embodiment of the present invention, all of the first to third detection units are provided as one example, but are not necessarily required, and according to the coal supply environment of the coal-fired power plant and the combustion control system, One or two of the three detection units may be selectively installed and operated.

As described above, the present invention has the effect of quantitatively accurately measuring the supply state of coal powder by detecting the static electricity of coal powder in a conduit in which coal powder is supplied from the mill to the boiler.

Claims (3)

In coal-fired power plant in which coal powder, which is micronized from the pulverizer, is supplied through a conduit, is mixed with air through a damper at a predetermined ratio and injected into a boiler. A detection unit installed at a specific point inside the conduit to detect static electricity of coal powder particles; Another detection unit installed inside the conduit at a point separated by a set distance in the longitudinal direction of the conduit from the detection unit to detect static electricity of coal powder particles; Comparing the electrostatic waveforms of each of the detection unit to obtain a time difference between the electrostatic waveforms coincide with each other, and through this control means for calculating the coal moving speed in the conduit, characterized in that it comprises a coal supply state measuring apparatus of the coal-fired power plant . The method of claim 1, wherein the detection unit, A probe composed of a conductor to collect static electricity through friction with coal particles, Fixing means for fixing the probe to the conduit; Apparatus for measuring a coal supply state of a coal-fired power plant, characterized in that it comprises a connecting means for electrically connecting the probe and the control means. The method of claim 1, wherein the detection unit, A plurality of probes composed of a conductor and collecting static electricity through friction with coal powder particles, Fixing means for fixing the plurality of probes to the conduit; Apparatus for measuring a coal supply state of a coal-fired power plant, characterized in that it comprises a connecting means for electrically connecting the probe and the control means.