JP2005147847A - Method and instrument for measuring ash level in ash fusion furnace hopper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and instrument for measuring an ash level in an ash fusion furnace hopper capable of grasping correctly an actual holding amount or a holding condition. <P>SOLUTION: In this method, a microwave is emitted from a microwave emission/reception device provided in a ceiling of the ash fusion furnace hopper, the emitted wave reaches an ash level face in the hopper, a reflected wave reflected on the ash level face is received by the ash fusion furnace hopper, a travel time from the emission to the reach is analyzed to measure a height of the ash level face, and an emission angle of the microwave is brought within a range expressed by θ(°) in Expression (1). Expression (1): 2tan<SP>-1</SP>(S/H)≤θ≤2tan<SP>-1</SP>(D/2H), where H: a distance (mm) from the highest ash level in the hopper to the microwave emission/reception device, S: the maximum diameter of particles in a particle distribution of ashes, and D: a diameter (mm) of the hopper. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a melting furnace for recycling heavy oil-fired boiler fly ash, coal-fired boiler furnace ash, various waste incinerator ash, etc. in a high-temperature furnace such as a plasma melting furnace. The present invention relates to a method and an apparatus for measuring an ash level of a hopper using a microwave. More specifically, the present invention relates to a method and apparatus for quantitatively grasping the state in which ash having a large angle of repose is accumulated and held inside a hopper attached to an ash melting furnace using microwaves.

  Conventionally, in order to grasp the amount of raw material (ash) held in this kind of raw material (ash) supply hopper, the raw material (ash) is weighed when it is introduced by the hopper conveyor or the like (for example, patent) There is a method of placing the entire hopper on a load cell and directly weighing the total weight charged. Since the ash temporarily held in the hopper is supplied from the bottom of the hopper to the melting furnace by a pusher or the like, the ash holding amount in the hopper is determined as If the supply from the hopper to the melting furnace is balanced, it is kept constant, but if the latter fluctuates, even if the former progresses quantitatively, the hopper holding amount fluctuates and its current value is unknown. In other words, the supply rate to the melting furnace cannot be adjusted unless the true hopper holding amount can be kept constant or grasped. In addition, in the gross weight measurement method, the hopper is not mounted on the load cell in a state where stress fluctuations derived from ash charging means such as a screw feeder or ash supply means from the hopper such as a pusher to the furnace are insulated. It has to be done and it is not always easy.

  In order to avoid these problems, a method of measuring the level of ash in the hopper with a paddle type level detector as shown in FIG. 4 is also performed. This will be described below. Ash is put into the hopper 1 with a screw feeder 4. The ash 5 temporarily held in the hopper is supplied into the ash melting furnace 6 by the pusher 3 provided at the bottom. In the hopper, a paddle type level detector 10 is provided at positions H, M, and L to detect the height of the ash particles. However, ash has a large angle of repose, so when it is discharged from the bottom, it forms a level 7 surface that is recessed in the middle. Therefore, the amount of ash retained in the hopper estimated from the particle surface height detected from the paddle type level detector has a significantly large error.

  On the other hand, Patent Document 2 discloses a method using a microwave as a method for measuring the level of a granular material and a fluid in a non-contact manner without being affected by heat, dust, environmental gas, and other media. Yes. This technique is useful and applicable to the aspect that is not affected by the adverse environment described above when the level surface forms a stable surface that is relatively close to horizontal, but is within the consciousness of the present invention. Such a level surface that forms a significantly changed profile still has a significant error.

  Patent Document 3 also discloses a measurement method using microwaves as a method for measuring the layer height using reflected waves. This technique measures the bed height of the fluidized bed, and the level surface of the fluidized bed is inherently fluctuating, so the measured values are highly variable. Therefore, when the bed height is used as an operation management index, it is regarded as a frequency distribution of measured values having large variations. This problem is a problem of temporal variation of measured values, and is different from the problem of the geometrical shape of the level surface, which is a problem of the present invention.

JP 2000-65334 A JP-A-10-185147 JP-A-9-89632

  The present invention has been made in view of the above-described problems of the prior art, and an object thereof is to provide a method and apparatus for measuring the ash level of an ash melting furnace hopper capable of correctly grasping the actual holding amount or holding state. More specifically, the aim is to provide a method and apparatus for measuring the average value of the ash level of the ash melting furnace hopper or measuring the cross-sectional profile of the level surface to correctly grasp the actual holding amount or holding state. To do.

Therefore, the ash level measuring method of the ash melting furnace hopper according to the present invention radiates microwaves from the microwave radiation / reception device provided on the ceiling of the ash melting furnace hopper, and the radiated waves are ash level surfaces in the hopper. The reflected wave reflected by the ash level surface is received by the microwave radiation / reception device, the process time from radiation to arrival is analyzed, and the height of the ash level surface is measured. The microwave radiation angle is in a range indicated by θ (°) in the equation (1).
2 tan ⁻¹ (S / H) ≦ θ ≦ 2 tan ⁻¹ (D / 2H) (1)
H: Distance (mm) from the highest ash level in the hopper to the microwave radiation / reception device
S: Max diameter of particles in ash particle size distribution D: Diameter of hopper (mm)

  The frequency of the microwave used here is not particularly limited unless the wavelength is short enough to be affected by the dust particles in the hopper, but the general property that the radiation beam is likely to spread at longer wavelengths is considered. May be. The basis of the inequality (1) will be described with reference to FIG. 2. The maximum value is the radiation angle θ at which the beam spreads in a range covering the entire bottom surface of the hopper having the height H and the diameter D (a), A range having a size twice as large as the largest ash particle on the bottom surface was defined as the minimum value (b). A microwave having a radiation angle θ in this range is reflected at the level 7 of the ash 5 and the reflected wave is received. The signal obtained by changing the level plane in the range covered by θ in FIG. It has information. Therefore, by analyzing this signal, for example, the average height of the level surface in the range covered by θ can be calculated.

  Further, according to the ash level measuring method of the ash melting furnace hopper of the present invention, a microwave is radiated from a microwave radiation / reception device provided on the ceiling of the ash melting furnace hopper, and the radiated wave is applied to the ash level surface in the hopper. A method of measuring the height of the ash level surface by receiving a reflected wave that reaches and reflects on the ash level surface with the microwave radiation / reception device, analyzes a process time from radiation to arrival, and The microwave radiation is scanned in the hopper diameter direction, and the height of the ash level surface corresponding to a plurality of positions on the diameter is measured. A cross-sectional profile of a level surface is obtained by associating the measurement value with an orthogonal coordinate whose height is taken on the vertical axis.

  As the scanning method, it is possible to rotate the vicinity of the attachment position of the microwave radiation / reception device as an axis and change the angle. Further, it is possible to horizontally move the microwave radiation / reception apparatus by sliding it on the diameter.

Furthermore, an ash melting furnace hopper ash level measuring apparatus according to another aspect of the present invention includes a microwave radiation / reception device provided on a ceiling of the ash melting furnace hopper, and a microwave radiation from the microwave radiation / reception device. Then, the radiation wave reaches the ash level surface in the hopper, the reflected wave reflected by the ash level surface is received by the microwave radiation / reception device, and the process time from radiation to arrival is analyzed, Analysis / calculation means for calculating the height of the ash level surface, the microwave radiation / reception device further comprising radiation angle forming means, and the radiation angle of the radiation microwave is expressed by θ ( °) in the range indicated.
2 tan ⁻¹ (S / H) ≦ θ ≦ 2 tan ⁻¹ (D / 2H) (1)
H: Distance (mm) from the highest ash level in the hopper to the microwave radiation / reception device
S: Max diameter of particles in ash particle size distribution D: Diameter of hopper (mm)

  The radiation angle forming means can be performed, for example, by using an electromagnetic horn as an antenna. It is also possible to use an electromagnetic lens made of a substance having an appropriate dielectric constant.

  Furthermore, an ash level measuring apparatus for an ash melting furnace hopper according to the present invention includes a microwave radiation / reception device provided on the ceiling of the ash melting furnace hopper, and a microwave radiated from the microwave radiation / reception device. Reaches the ash level surface in the hopper, the reflected wave reflected by the ash level surface is received by the microwave radiation / reception device, and the travel time from radiation to arrival is analyzed, and the ash level surface of the hopper is analyzed. Analyzing and calculating means for calculating the height, and the microwave radiation / reception device further comprises a scanning means in the hopper diameter direction, and the microwave radiation is scanned in the hopper diameter direction, and a plurality of positions on the diameter are provided. The height of the ash level surface corresponding to the level surface is measured, the position on the diameter is plotted on the horizontal axis, and the measured value is made to correspond to the orthogonal coordinates where the height of the ash level surface is plotted on the vertical axis. Of cross-sectional profile Wherein the resulting allowed the.

As described above, the effects of the present invention can be summarized as follows.
(1) The level surface can be measured using microwaves without being affected by environmental factors such as dust, temperature, pressure, and medium material.
(2) If the radiation angle is widened and the reflected wave is received and analyzed, the average height of the level surface that is not horizontal can be calculated.
(3) Alternatively, if the reflected wave is received and the height is measured while scanning the level surface with microwaves, a cross-sectional profile of the level surface can be drawn and the level state can be grasped.
As a result, measurement with high accuracy cannot be performed in the past, which has hindered control of the ash melting furnace, but is improved.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.

FIG. 1 is a schematic diagram showing an embodiment of an ash level measuring method for an ash melting furnace hopper according to the present invention. In FIG. 1, when the ash 5 is introduced by the screw feeder 4 and supplied into the ash melting furnace 6 by the pusher 3, the ash 5 in the hopper 1 becomes a level 7 surface having a non-flat concave shape as shown in the figure. . Since the height of the hopper is 3000 mm and the diameter is 1000 mm, 2tan ⁻¹ (D / 2H) in the formula (1) is 18.9 °. A horn antenna is attached to the microwave radiation receiving apparatus 2 so that the microwave radiation angle is 18.9 °.

Microwave radiation is frequency modulated linearly with respect to the time axis between 10 GHz from 9 GHz, along a straight line in FIG. 3 (a) F _rd, when radiation to a saw-like change, in the drawing A reflected wave such as F _rf is received. The upper reflected wave is reflected from the nearest (higher level) surface of the concave level surface, and the lower reflected wave is reflected from the farthest (lower level) surface of the concave level surface. Is. Since the concave level surface changes substantially continuously, the inside of the broken line shown by the dotted line in FIG. 3 is almost continuously filled with the same broken line. Since the difference ΔF between the frequency of the radiated wave and the reflected wave at the same time is proportional to the distance to the level surface, the distance can be calculated. When ΔF is illustrated in terms of time, it is as shown in (b), where ΔF _max is a value proportional to the distance to the farthest (low level) surface and ΔF _min is proportional to the distance to the nearest (high level) surface. Using these signals or numerical values obtained from these signals, a unique index such as an average level, a median level, or a definition value that can be calculated by integral calculation may be calculated as the hopper ash level.

  This invention can grasp | ascertain the holding amount accurately by improving the ash level measuring method held in the hopper attached to an ash melting furnace. As a result, it is possible to appropriately control the melting reaction process of ash discharged from various industries, which is useful for recycling industrial waste.

1 is a schematic diagram showing an embodiment of an ash level measuring method for an ash melting furnace hopper according to the present invention. It is the schematic which shows the basis which limits the range of the radiation angle of the microwave of this invention. 6 is a graph showing a reflected wave of a microwave irradiated with a predetermined radiation angle on a certain level surface according to an embodiment of the present invention. It is a schematic diagram showing an embodiment of a conventional level meter.

Claims (4)

A microwave is radiated from a microwave radiation / reception device provided on the ceiling of the ash melting furnace hopper, the radiated wave reaches an ash level surface in the hopper, and a reflected wave reflected by the ash level surface is reflected by the microwave. A method of measuring the height of the ash level surface by analyzing a process time from radiation to arrival by receiving with a wave radiation / reception device, wherein the microwave radiation angle is expressed by θ ( A method for measuring the ash level of an ash melting furnace hopper, characterized in that it falls within the range indicated by °).
2 tan ⁻¹ (S / H) ≦ θ ≦ 2 tan ⁻¹ (D / 2H) (1)
H: Distance (mm) from the highest ash level in the hopper to the microwave radiation / reception device
S: Max diameter of particles in ash particle size distribution D: Diameter of hopper (mm)   A microwave is radiated from a microwave radiation / reception device provided on the ceiling of the ash melting furnace hopper, the radiated wave reaches an ash level surface in the hopper, and a reflected wave reflected by the ash level surface is reflected by the microwave. A method of measuring the height of the ash level surface by scanning the microwave radiation in the hopper diameter direction, receiving the wave radiation and receiving device, analyzing the process time from radiation to arrival, The height of the ash level surface corresponding to a plurality of positions on the diameter is measured, and the measured value is set to orthogonal coordinates where the position on the diameter is taken on the horizontal axis and the height of the ash level surface is taken on the vertical axis. A method for measuring the ash level of an ash melting furnace hopper, characterized by obtaining a cross-sectional profile of the level surface in correspondence. A microwave radiation / reception device provided on the ceiling of the ash melting furnace hopper, and a microwave is radiated from the microwave radiation / reception device, the radiation wave reaches an ash level surface in the hopper, and the ash level Analysis / calculation means for receiving a reflected wave reflected by a surface by the microwave radiation / reception device, analyzing a process time from radiation to arrival, and calculating a height of the ash level surface; Ash level measurement of an ash melting furnace hopper characterized in that the microwave radiation / reception device includes radiation angle forming means, and the radiation angle of the radiation microwave is in a range indicated by θ (°) in the equation (1). apparatus.
2 tan ⁻¹ (S / H) ≦ θ ≦ 2 tan ⁻¹ (D / 2H) (1)
H: Distance (mm) from the highest ash level in the hopper to the microwave radiation / reception device
S: Max diameter of particles in ash particle size distribution D: Diameter of hopper (mm)   A microwave radiation / reception device provided on the ceiling of the ash melting furnace hopper, and a microwave is radiated from the microwave radiation / reception device, the radiation wave reaches an ash level surface in the hopper, and the ash level Analysis / calculation means for receiving a reflected wave reflected by a surface by the microwave radiation / reception device, analyzing a process time from radiation to arrival, and calculating a height of the ash level surface; The microwave radiation / reception device includes scanning means in a hopper diameter direction, scans microwave radiation in the hopper diameter direction, measures heights of the ash level surface corresponding to a plurality of positions on the diameter, and The ash is characterized in that the cross-sectional profile of the level surface can be obtained by associating the measured value with the orthogonal coordinates with the position on the diameter on the horizontal axis and the height of the ash level surface on the vertical axis. Melting furnace hopper Level measuring device.

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