TW491943B - Density measuring device for granulated material - Google Patents

Abstract

A density measuring device for granulated material uses a electrostatic sensor to detect current (AC) generated in the main electrode by electrostatic conduction, and calculates the density of the granulated material inside the channel from detected current via a calculation part. Since it is possible to avoid being affected by the current depending on the variation of the flow rate and the particle size, therefore a measurement of high precision is achieved.

Description

491943 V. Description of the invention (1) The present invention relates to the measurement of powders such as coal dust, flour or cement, or particles such as resin particles (hereinafter collectively referred to as "powder and granules") used to measure the transport of mixed air flow in pipes. ) Concentration of powder and particle concentration measuring device. In the past, the methods used to measure the flow of powder and granules in the solid / gas two-phase flow in the exhaust pipe of the chimney used the light transmission type and the charge type method (refer to Masuda Hiroaki "Powder: / Mouth Seven: © Measure Seven Masters, published in 1997, Volume 12, "Mechanical Design," p. 8b, 88). The light transmission type is the most commonly used measurement method at present, and it is provided with a light emitting part and a light receiving part in a pipe, and the intensity of the light that is not attenuated by the particles of the powder and granules is attenuated to the side. According to this method, although there is a benefit point that is not easily affected by changes in the material, type, or humidity of the powder and granules, once the particles of the powder and granules are attached to the light-emitting portion or the light-receiving portion, the measurement accuracy is significantly reduced, and may even decrease. When the light bulb of the light source of the light emitting part breaks, maintenance must be performed frequently to maintain accuracy, which causes a problem of high maintenance cost. As for the charging method, a measurement method using the charging phenomenon of particles of powder and granules is shown in the fifth figure (a). The particle 3 in the pipe 2 is measured by the collision (friction) detection body (probe) 5. There are two methods of the amount of moving charges, and two methods of measuring the amount of charges moving when the particles 3a frictionally charged in the duct 2 contact the detector 5 as shown in the fifth figure (b). The detection body 5 is installed in the pipe 2 with electrical insulation. Compared with the light-transmitting method, this method has the advantage of reducing the regular maintenance work. However, these conventional charging methods have the following problems because they capture the two types of charge movement (ie, direct current) generated by collision friction and contact with charged particles. That is, (1)

491943 V. Description of the invention (2) Changes occur, the collision force of the particles colliding with the detection body 5 changes accordingly, and the charge amount changes accordingly. (2) If the spherical diameter of a particle changes, the collision force also changes as the flow velocity changes. (3) If the particles are attached to the detection body 5, the detection body 5 is covered by the attached particles, and the surface area receiving charge movement is reduced, and the amount of charge changes accordingly. Due to these problems, the conventional charge-type measuring device is affected by changes in flow velocity or particle size, and there is a problem that the measurement accuracy cannot be improved. For example, when the particle 5 does not collide with the detection body 5, there is a problem that the measurement cannot be performed. . In addition, at the root of the detector 5 installed in the pipe 2, the particles are most likely to stay and cause their concentration to be higher than the normal concentration in the pipe 2, and sometimes cause abnormal concentration measurement results. In order to cover the outer periphery of the pipe 2 for the sake of safety, it is necessary to provide a flange formed by the protruding cylindrical portion 4a and the outer end of the pipe 2 as shown in the first figure (b). The detector 4 is mounted on the installation part 4 formed by the part 4b. In this case, the particle mobility between the cylindrical part 4a and the detector 5 is poor, and it is particularly easy to stay, so that the concentration of this part is higher than that of the pipe. The normal concentration in 2 is abnormally high. Therefore, the concentration of powder and granules is greatly affected by the position in the pipe. An object of the present invention is to provide a concentration measuring device capable of measuring the concentration of powders and granules with high measurement accuracy under the influence of changes in flow velocity, particle size, and even the installation site in a pipeline while solving the foregoing problems. In order to achieve the above object, the powder-granularity concentration measuring device according to the present invention has a main electrode protrudingly arranged in a pipe for detecting

491943 V. Description of the invention (3) The electrostatic induction detection part of the current generated in the main electrode caused by the electrostatic induction caused by the movement of the charged powder particles flowing in the pipeline, and the current flowing through the above is calculated based on the detected current. Calculation unit for the concentration of powder and granules in a pipe. According to this structure, the current generated by the electrostatic induction of the main electrode, that is, the alternating current is detected by the electrostatic induction detection section, and the calculation section calculates the concentration of the powder and granules in the pipeline based on the detected current, which can avoid the impact of the flow velocity. The current affected by the change or the different size of the particles, that is, the effect of the direct current, can achieve high measurement accuracy. In a preferred embodiment of the present invention, all or a part of the main electrode is further covered with an insulating layer, and the root of the main electrode is covered with the insulating layer to ground the electrode. According to this structure, because the ground electrode is located in the root of the main electrode, which is likely to cause abnormalities in the concentration of powder and particles in the pipeline, the current in this part will be absorbed by the ground to eliminate the data that caused the abnormal concentration, and a very high measurement accuracy can be obtained. In another embodiment of the present invention, the pipe is provided with a mounting portion composed of a cylindrical portion protruding outward and a flange portion formed at a front end thereof, and the electrostatic induction detecting portion is mounted on the flange portion, and the above The ground electrode is disposed in the cylindrical body portion. According to this structure, a ground electrode is provided at a place where the powder and granules are particularly liable to stagnate, so that the abnormal concentration information in this part can be eliminated, so that high measurement accuracy can be obtained. According to another embodiment of the present invention, an alarm is issued on the output side of the calculation unit to issue a high-concentration detection result based on the output signal of the calculation.

491943 V. Description of invention (4) Newspaper department. With this structure, it is possible to accurately measure the concentration regardless of the change in flow rate, the size of the powder particles, and the installation site in the pipeline, and to send an alarm when a high concentration is detected. The preferred embodiments of the present invention are described in detail below with reference to the drawings. However, it must be stated here that the various embodiments shown are for illustration and expression only, and are not intended to limit the scope of the present invention. The scope of the present invention is hereinafter As defined by the scope of patent applications. In the drawings, the same or equivalent components shown in a plurality of drawings are indicated by the same symbol. The first diagram shows the structure of a solid-gas two-phase flow concentration measuring device for measuring the concentration of coal dust (particulate matter) in the flue gas according to the first embodiment of the present invention. In the first diagram (a), The flue gas discharged from the boiler 11 is sucked into the dust collector 12 by the blower 1 and is collected by the dust, and then sent to the chimney 13 through the pipe 2 (pipe), and then the smoke is discharged into the atmosphere from 13. The exhaust gas is a solid-gas two-phase flow containing exhaust gas and coal dust, and as shown in the first figure (b), the coal dust particles 3a in the pipe 2 become a solid-gas two-phase flow M dispersed in the exhaust gas. Directional delivery. The coal dust particles 3a in the pipe 2 collide with the pipe 2 and are frictionally charged or charged by the electric field induction of the dust collector 12. The peripheral wall of the pipe 2 is provided with a mounting portion 4 formed by a cylindrical body 4a protruding outward and a flange 4b formed at the front end thereof. An electrostatic induction detecting portion 8 is fixed to the flange 4b of the mounting portion 4 and faces the pipe 2 The axial direction of the vertical axis protrudes in a vertical horizontal direction, and is used to detect the charged amount of the coal dust particles 3 a in the solid-gas two-phase flow M in the pipeline 2. This detecting section 8 is constituted by, for example, a rod-shaped probe body (probe) 5 of a round rod type, a ground electrode 6 and a detector 7 in this embodiment. in

491943 V. Description of the invention (5) In this example, the probe body 5 is a round rod shape, but it can also be a flat plate or a cylindrical shape. The ground electrode portion 6 is arranged in the cylindrical body 4 a of the mounting portion 4. As shown in the second figure (a), the probe or probe 5 of the electrostatic induction detection unit 8 includes a cylindrical main electrode 21 and an insulator 24 covering the entire main electrode 21. The detector 7 is used to detect the electric current generated by the charged coal dust particles 3 a flowing in the pipeline 2 at the main electrode 21 due to the movement of electrostatic induction, that is, the alternating current. The detected current includes, in addition to this AC component, a DC component generated when the medium dust particles 3 collide with the detection body 5 and the charged coal dust particles 3 a come into contact. The detected current is processed by the input control unit 10. The control unit includes a signal processing unit 14 and a calculation unit 15. The signal processing unit 14 has a conventional filter circuit such as a band-pass filter, which can extract only AC components in a predetermined frequency band region from the detected current, and the medium dust particles 3 collide with the sensor body 5 and charged coal dust. The DC component generated by the particle 3 a contact is cut off by the filter circuit. The calculation unit 15 calculates the concentration of the powder and granules in the pipe 2 based on the frequency and amplitude of the detected AC current and the relevant data stored in advance in a memory (not shown). In addition, the alarm unit 16 issues a high-concentration alarm when the AC current (calculated output) taken out by the calculation unit 15 described above exceeds a reference value. The alarm section 16 can be configured using, for example, a buzzer, an indicator lamp, or both. The configuration of the electrostatic induction detection unit 8 of the present invention will be described in detail below. As shown in the third figure, the cylindrical main electrode 2 1 constituting the probe 5 is supported at its rear end by a main electrode support 2 1 a extending in its axial direction. A protrusion is fixed at the front of the main electrode support 21 a.缘 23。 Edge 23. Main electrode 21, main electrode support

V. Description of the invention (6) 2 1 a and flange 2 3 are all covered with fluoroethylene resin) Insulation compound coal dust particles are not easy to adhere, for example, PTFE (poly-quad plate test body 5 adheres to coal dust ^ body 2 4, 3 2. The present invention Although the structure will not be affected even if the amount is too large, it will not be affected by the material as the insulator 24, so the stainless steel 23 which is not easily attached by coal dust can be used. °, the electrode 21, the main electrode support 21a and the flange 30, and the main electrode support secondary edge 2 3 is locked and fixed to the ground electrode support 4, which will be described later in detail. The body 21 & supports the main electrode 21 The insulator fixed to the electrode of the mounting part is regarded as a ceramic. If inorganic particles such as ceramics and glass can be used in the case of high-temperature-resistant, heat-resistant electricity such as resins, rubbers, ceramics, etc. The insulator covering this electrode can be used. For example, the heat-resistant insulating main electrode 21 of heat-resistant resin such as PTFE is composed of the inner surface of the insulator 24, and the insulator 24 is coated with its front and rear ends fused in This flange 23 is insulated from the rear end of the insulator 24 The above-mentioned flange 23 is attached, such as the near-installed root of the electrode 21: integrated into a body. The insulator 2 4 is located around the main pole 6 and a cylindrical ground electrode 6 is sheathed by a grounding mine at the base. This ground electrode support 30 It is held in electrical connection, and is adopted by the ground electric electrode and the ground electrode support Γο :; 4, two pipes 2. The front end portion of the ground ground electrode 6 and the steel product of the insulator. 25, the nut 25 passes through the washer 26 A lock nut is provided between the ground electrode and the ground electrode 6 and the spacer 24 of the insulator 24 is screwed into the ground electrode 6 to isolate and seal the state. During this time, for example, when + + forms a gap with the internal space of the pipe 2, it senses The body 5 will be shaken by the influence of the fifth invention description (7), and the + n ΐ electrode support 2 1 a and the flange 2 3 are also covered by the insulator 3 2, and the electric support 30 is tightly fitted here. The outer periphery of the insulator 32. Body 3. The front support half body 30a and the rear support half body 30: ground are formed with flange-shaped mounts for mounting on the flanges 4b. Mounting μμ meditation: This mount uses multiple It is also possible to fasten the worms 34 to the wall of Anzhou 7 If it is fixed to the pipe with urea resin 2 There is a locking cicada mother for 28 months, and the female 28 is locked between the rear end of the body 30a and the insulator 32, and is locked into the front branch via the washer 29: the flange portion of the insulator 32 is filled with the flange 23 The gap 3 + ^ + body 30a is fixed at the bottom surface (mounting surface) 37 of the recessed portion. It is connected to the front support 2 = the main electrode support 21a fixed to the flange 23, and the electrode f 疋 is located at the front of the anchoring section 4. The rear end of the supporting half body 30a is used to support the solid threaded portion of the half body 30a, and the front end portion of the rear supporting body 30b is provided with a female perimeter *. A first male half body 30b is provided on the surface to thereby pass The washer 3ι is screwed into two, two, and the Ministry of Education. The rear support front support half 30a is connected to form a ground: = the threaded part is connected to the back. The rear support half 30b is provided with a second male screw neodymium ▲控 体 30. The outer shell 35 of the circuit of the detector 7 is a male screw. The male threaded part ^ 卩 'is internally equipped with: owing to the electrostatic induction of the first embodiment ^ ° Ming · 4 8 The effect of the first figure (a) concentration measuring device The static electricity is the same as that of the cylindrical Faraday cage. As described above, it is completely shielded by the structure of the main to pre-measurement unit 8. Due to the charged coal dust in the main electrode 21 and the movement of the detector 7 f 3a

Page 10 491943 V. Description of the invention (8) Electrostatic induction acts on the free electrons in the osmium electrode 21 in the equilibrium state, and as shown in the second figure (b), the electrons of the main electrode 21 are placed on the detector 7 Moves within the circuit of, generates a current i (t) as shown in the first figure (c). In other words, when the coal dust particles 3 a in the pipeline 2 pass near the detection body 5, as shown in the fifth figure (c), the coal dust particles 3 a with a jade (+) charge are replaced by the conductor ( That is, when the main electrode 2 1), a negative (-) electric symbol of opposite sign (polarity), ^ ^ appears near the conductor, and the same polarity A (0) appears on the side. The coal dust particles 3a — the body recovers the charge. The state of equilibrium being neutralized. Subsequently, as in the H ^ state, the main electrode 21 generates an alternating current i (t). Therefore, when these two highs are repeated, the amplitude of the alternating current i (t) also increases, while ' If the concentration increases with the positive charge and the negative charge return to the equilibrium state, the electrode 2 1 ^ should be reversed. If the concentration decreases, the amplitude decreases, and the frequency increases. At the same time, the concentration of the powder is used. The detected AC rate is also lowered. The unique correlation between the current rate and the developed density meter = current amplitude and frequency. The detector 7 in the second figure (a) detects this AC ^^ method. Voltage conversion The circuit 7a is transformed into the second figure (1/0 of (1)), which is converted by current flow-voltage Even if the return resistance of the circuit 7a changes to "voltage v (t)", the electrical impedance makes the input impedance very small, so it does not = because of the negative return amplifier, it also has the characteristics of high sensitivity and low noise. A special one must be selected. The p-processing unit Γ4 :: The detection current detected by the device 7 is filtered by the filter circuit of the control unit-μ ° 卩 14 to filter out the AC current component. The signal of the flat 疋 10 collides with the body 5 or the charged medium dust particles 3 collide.

The part is cut off by the contact of Λ with the probe 5 Λ J " Piece cut. Finally ’from the calculation department 15 from? The frequency of the parent current generated by the direct current generated by the contact 491943 V. Description of the invention (9) ~ 1 --- --- and the amplitude, according to the concentration of the powder and granule recorded by the memory device. It is possible to calculate the relevant information stored in the pipeline 2 by borrowing 1 on the main electrode 21 and covering the insulator 24 at the same time. It is not related to changes in flow velocity or coal dust particles tf to dust particles 3 a to the sensor body 5 ", Small, not too" Also, by the production of μ 龃 邱] R: Erxiang can measure its concentration with high accuracy. Reference value day * Calculated AC current taken in by the second part 15 of Ershan 丄 Ϊ is more than chemical ： 'Pl describes the alarm detected by the concentration, such as A, it is not affected by the flow rate change =: Left and right of the installation position in the pipeline 2 can be finely married ~ the same / Chen detection alarm. # 丨 夕 别 ^ On the one hand, the ground electrode 6 is arranged between the cylinder 4a and the sensing body in the pipe 2, that is, the coal dust particles are easily trapped and the concentration of the powder is changed to the root of the main electrode 21. Therefore, the ground electrode The occurrence of 6 = machine is not taken in by the detector 7, and the signal of this abnormal concentration is directly grounded to E to eliminate noise, so a higher measurement accuracy can be obtained. The fourth figure shows the second embodiment The structure of the sensing body 5A of the electrostatic induction detecting section 8A is shown. In this second embodiment, the main power of the detecting body 5A is The entire surface of the pole 21 is not provided with an insulator to cover it, which is different from the first embodiment. This device is suitable for the measurement of the concentration of powders and granules in the south temperature, because the temperature is higher than 2 & At this time, the powder and granules do not contain moisture and are not easily attached to the main electrode 2 1 ′, so it is not necessary to completely cover the insulator 2 1, but the main electrode 2 丨 and the ground electrode β must be insulated, so only the main electrode 2 Part of 丨 is provided with insulator 2 4A. At high temperatures above 250 ° C, insulators such as PTFE will be melted off. Therefore, in this inert shape, insulators 2 4 A and 32 are suitable for use. High temperature resistant ceramic material. In addition, the front end of the insulator 2 4 A protrudes from the ground electrode 491943 5. The front end of the invention description (ίο) to take a large insulation extension distance. Also, the installation of the second embodiment The method is different from that of the first embodiment in which the electrostatic induction detecting portion 8 is fixed to the mounting portion 4 by a flange, but the electrostatic induction detecting portion 8 A is directly screwed into the pipe through the front male screw portion of the ground electrode support 30. Thread holes 3 8 provided on the peripheral wall, and nuts 3 6 through pads 3 9 is tightly fixed. As for the structure of other parts is the same as that of the first embodiment, it is not easy to repeat them here. According to this second embodiment, it is not affected by the flow rate change or the size of coal dust particles 3 a like the first embodiment, or The coal dust particles 3 a are attached to the sensor body 5 A, and the ground electrode 6 is provided at the root of the probe body 5 A where the coal dust particles 3 a are liable to stay. Therefore, the current generated by the ground electrode 6 can be similar to the first embodiment. Grounding eliminates the abnormal concentration signal, so high measurement accuracy can be obtained. Each of the above embodiments is provided with a grounding electrode, but this grounding electrode can also be omitted. If an air purge unit (not shown) is provided here It is also feasible to replace the ground electrode or co-located with the ground electrode. This air purging part is formed by drilling an air passage for compressed air to pass through the front support half of the ground electrode support body, and aligning its outlet with the root of the sensor body, and introducing compressed air from the outside to blow The roots of the sensing body where coal dust particles are susceptible to stagnation can be used to blow away the coal dust particles, thereby preventing the coal dust particles from staying at the root of the sensing body. The above only describes the preferred embodiment of the present invention with reference to the accompanying drawings. However, those skilled in the art can easily make various changes and modifications from the content of this specification within the scope that is clearly known. Therefore, all such obvious changes and modifications should be Deemed to encompass the scope of the invention as defined by the scope of the following patent applications

Page 13 491943 V. Description of the invention (11) 491943 Brief description of the drawings The first diagram (a) shows a schematic diagram of an exhaust system to which a coal dust particle concentration measuring device according to the first embodiment of the present invention is applied. The first figure (b) shows an enlarged partial cross-sectional view of the main part of the device of the first figure (a). The second figure (a) shows a schematic configuration diagram of the concentration measuring device of the first embodiment. The second graph (b) is a characteristic diagram showing a change in the amount of electric charge of the coal dust particles in the electrostatic induction detecting section. The second graph (c) shows a characteristic diagram of the current output from the detection electrode. The second graph (d) shows a characteristic diagram of the output voltage signal. The third figure shows a detailed structural sectional view of the electrostatic induction detecting section according to the first embodiment of the present invention. The fourth figure is a sectional view showing the detailed structure of the electrostatic induction detecting section according to the second embodiment of the present invention. The fifth diagrams (a) to (c) are schematic diagrams showing how the powder particles move in the duct. Explanation of symbols: 1 blower 2 duct 3 powder particles (coal dust) particles 3a charged powder particles (coal dust) particles 4 mounting portion 4a cylinder 4b flange 5, 5A deep measuring body (probe) 6 ground electrode 7 detector 7a Current-voltage conversion circuit 8, 8A Static induction detection unit 10 Control unit 11 Boiler

Page 15 491943 Brief description of drawings 12 Dust collector 13 Chimney 14 Signal processing section 15 Calculation section 16 Engine section 21 Main electrode 21a Main electrode support 23 Flange 24, 24A, 3 2 Insulator 25, 28, 36 Lock nut 26, 29, 31, 39 Washer 30 Ground electrode support 3 0a Front support half 30b Rear support half 33 Interstitial gasket 34 Screw 35 Detector housing 38 Threaded hole

Page 16

Claims (1)

491943 VI. Scope of patent application 1. A powder and granule concentration measuring device, comprising: a main electrode protrudingly arranged in a pipe, and capable of detecting when the charged powder and granule particles flowing in the pipe are moved; An electrostatic induction detecting unit that generates an electric current in the main electrode through electrostatic induction, and a calculation unit that calculates the concentration of powder and granules in the pipe based on the detected current. 2. The powder and particle concentration measurement device according to item 1 of the scope of the patent application, further comprising a ground electrode covering the root of the main electrode by covering all or part of the insulation of the main electrode. . 3. The powder and particle concentration measurement device according to item 2 of the scope of the patent application, wherein the peripheral wall is provided with a cylinder formed by protruding from the peripheral wall and a flange formed at a front end portion of the cylinder. The electrostatic induction detection unit is installed in the mounting unit, and the ground electrode is accommodated in the cylinder. 4. The powder and particle concentration measurement device according to any one of claims 1 to 3 of the scope of the patent application, further comprising an alarm unit that issues a high-concentration detection alarm based on the output signal of the calculation unit.