JPH06229801A - Measuring method for flow rate of powder - Google Patents

Abstract

PURPOSE:To provide a method for measuring a flow rate of powder flowing in a channel by an apparatus having a simple structure utilizing permeated and fluidized characteristics of a powder layer. CONSTITUTION:The method for measuring a flow rate of powder 11 in a channel 1A comprises the steps of providing a storage tank 2 and a vertical tube 3 in the channel 1A of the powder 11, communicating a lower end of the tube 3 with a side face of the tank 2 through a communicating part 4, introducing fluidized gases 12, 13 to a lower part of the tube 3 and the part 4, respectively while dropping the powder 11 in the channel 1A from an upper end of the tube 3 thereby to fluidize the dropped powder 11 to feed it from the part 4 into the tank 2, then stopping introduction of the gas 13 to the part 4 to maintain the powder 11 in the part 4 steady, and simultaneously measuring a change per unit time of a pressure difference DELTAp between a powder flow layer 14 and a powder layer 15 formed in upper and lower parts of the tube 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring the flow rate of powder flowing in a flow path.

[0002]

2. Description of the Related Art Measuring the flow rate of powder in order to improve the efficiency of the operation when transporting the powder or when performing the operation of circulating the powder or flowing out or flowing in a single device. It is useful. Examples of the powder used for such an operation include polymer resins, inorganic materials, foods, medical products, and organic crystals. For example, the polymer resin is piped in the form of powder or subjected to treatment such as fluidized drying. When a chemical reaction using a solid catalyst is carried out in a fluidized bed, a powdery catalyst is supplied or a circulating type fluidized bed is used. Further, powder coal is used in a coal fluidized bed boiler. In the case of performing the powder distribution operation as described above, when the powder flows in or out from the storage tank, the flow rate of the powder can be easily measured by measuring the volume or weight of the powder in the storage tank. Can be measured. However, when such a method cannot be applied due to other supply and removal of powder in the storage tank, a method capable of directly measuring the flow rate of powder in the flow channel is required. In such a case, hitherto, an impact powder flow meter or a slit type powder flow meter has been used to measure the powder flow rate.

The impact powder flow meter measures the force with which the powder flowing through the flow path collides with the impact detection plate by a strain gauge or the like and converts it into a powder flow rate. In addition, the slit type powder flow meter introduces the powder flowing in the flow path to the upper part of the container with slits, causes the accumulated powder to flow out from the slit on the side surface of the container, and weighs the weight of the powder held in the container. And the like to measure the flow rate of the powder.

[0004]

However, in the above-described conventional flow rate measuring method, mechanical obstacles such as a shock detecting plate and a container with slits are provided in the flow path of the powder, and the strain gauge and the electronic instrument for measuring the weight are provided. Since it is necessary to provide a formula detection terminal, there is a problem that powder particles are mechanically destroyed. In addition, depending on the powder to be handled, it may be hot or corrosive, so it is necessary to select an appropriate material for the flowmeter, and in addition, it is necessary to take sufficient consideration so that electronic parts do not ignite an explosion. There was a problem such as doing. It is an object of the present invention to improve the conventional flow rate measuring method to eliminate the above-mentioned problems.

[0005]

The structure of the present invention for achieving the above object will be described below with reference to the drawings. As shown in FIG. 1, the flow rate measuring method according to the first aspect of the present invention provides a storage tank portion 2 and a vertical pipe portion 3 in a flow path 1A of powder 11 and a lower end of the vertical pipe portion 3. Through the communication part 4 to the side surface of the storage tank part 2, and the powder 11 in the flow path 1A is dropped from the upper end of the vertical tube part 3 and the lower part of the vertical tube part 3 and the communication part 4 Flowing gas 12, 13
Is introduced to fluidize the powder 11 to flow into the storage tank portion 2 from the communicating portion 4, and thereafter, the introduction of the flowing gas 13 to the communicating portion 4 is stopped to stop the communicating portion 4. At the same time as the powder 11 in the inside is stopped,
A configuration for measuring the flow rate of the powder 11 in the flow passage 1A by measuring the amount of change in the pressure difference Δp between the powder fluidized bed 14 and the powder bed 15 formed in the upper and lower parts of the flow path 1A. Therefore, it can be said that it forms the basis of the present invention.

Further, in the flow rate measuring method according to the second aspect of the present invention, as shown in FIG. 2, a storage tank portion 2 and a vertical pipe portion 3 are provided in a flow passage 1B for carrying powder 11 by air flow. The cyclone 5 is connected to the upper end of the vertical pipe portion 3 and the lower end is communicated with the side surface of the storage tank portion 2 via the communication portion 4, and the powder 11 in the flow channel 1B is introduced into the cyclone 5. After separating from the gas, the falling powder 11 is made to flow by introducing the flowing gases 12 and 13 into the lower part of the vertical tube part 3 and the communication part 4 while dropping the powder 11 into the vertical tube part 3. The flow rate of the powder 11 in the flow channel 1B is measured by the flow rate measuring method according to the first aspect of the present invention.

Further, as shown in FIG. 3, the flow rate measuring method according to the third aspect of the present invention comprises a storage tank portion 2, an ascending pipe portion 6, a vertical pipe portion 3 having a cyclone 5 connected to the upper end thereof, and the vertical pipe portion. In the circulation type flow path 1C of the powder 11 in which the lower end of the pipe portion 3 is connected to the side surface of the storage tank portion 2 in the form of a loop, the communication portion 4 is sequentially connected in a loop shape. The powder 11 is supplied from the lower part of the part 2 to the lower part of the rising pipe part 6 to raise the rising pipe part 6 by air flow, and the rising powder 11 is introduced into the cyclone 5 and separated from the gas. While dropping the body 11 onto the vertical pipe portion 3, the vertical pipe portion 3
The fluidized gas 12, 13 is introduced into the lower part of the communication part 4 and the communication part 4 to fluidize the dropped powder 11 and return it from the communication part 4 to the inside of the storage tank part 2, and then the flow rate of the first invention. The circulating flow rate of the powder 11 in the flow channel 1C is measured by the measuring method. Note that in any of the above-described inventions, the communication section 4 is an L-shaped tube as shown in FIG.
It can be a U-shaped tube as shown in FIG. 2 or a powder flow container as shown in FIG.

[0008]

In each of the above-described inventions, the powder 11 that has fallen into the vertical pipe portion 3 is fluidized by the flowing gases 12 and 13 and flows from the communication portion 4 into the storage tank portion 2. After that, when the introduction of the flowing gas 13 into the communicating portion 4 is stopped, as shown in FIG. 1, the powder 11 in the communicating portion 4 is stationary, and all the powder 11 introduced into the vertical pipe portion 3 is accumulated. Then, the powder fluidized bed 14 and the powder bed 15 are formed on the upper and lower portions of the vertical tube portion 3. In the powder fluidized bed 14, the height ΔH increases due to the supply of the powder 11 from above, and the pressure loss Δp is expressed by the following equation. Δp = ΔH · (1−ε) ρpg ··· (1) where Δp = pressure loss, that is, the pressure difference (Pa) between the powder fluidized bed 14 and the powder bed 15 ΔH = powder fluidized Height of layer 14 (m) ε = porosity ρp = specific gravity of powder particles (kg / m ³ ) g = gravitational acceleration (m / s ² )

The powder quantity Q in the powder fluidized bed 14 is expressed by the following equation. Q = A · ΔH · (1-ε) ρp ··· (2) where Q = powder amount of powder fluidized bed 14 (kg) A = cross-sectional area of powdered fluidized bed 14, that is, vertical pipe Channel area of part 3 (m ² ) From equations (1) and (2) Q = A · Δp / g (3) Flow rate F of powder 11 in channel 1 is powder fluidized bed Since it is given as an increasing rate of the powder amount Q of 14, F = dQ / dt = A · d (Δp / g) / dt (4) where F = flow path 1 Flow rate (kg / s) of the powder 11 in the container t = time (s) Therefore, the amount of change in the pressure difference Δp / g between the powder fluidized bed 14 and the powder bed 15 in the vertical tube portion 3 per unit time d
When (Δp / g) / dt is measured, powder 1 is obtained from the equation (4).
The flow rate F of 1 can be obtained.

In order to measure the pressure difference Δp, an opening is provided in the powder fluidized bed portion and the powder bed portion of the vertical pipe portion 3, and a pressure difference between a water column type manometer and the like is provided through a pressure conduit between the openings. Although a pressure gauge may be connected, as shown in FIGS. 1 to 3, a pressure terminal 7 is provided at the position of the opening, and an electronic detector such as a semiconductor is provided as a differential pressure gauge 8 between the pressure terminals 7. If connected, the pressure difference Δp can be measured as an electric signal, which is convenient.

The powder 11 to which the method of the present invention can be applied must be suitable for forming the powder fluidized bed 14 in the vertical tube portion 3. Therefore, the size of the powder particles is 1 to
The range of 1000 μm is preferable, and the range of 20 to 500 μm is more preferable for obtaining better fluidity. Also,
The particle specific gravity is preferably in the range of 100 to 8000 kg / m ³ ,
The range of 300 to 2000 kg / m ³ is more preferable for obtaining better fluidity. The size of the vertical pipe portion 3 and the accompanying amount of the flowing gas 12 introduced therein are selected according to the range of the flow rate F of the powder 11. That is, the internal volume of the vertical pipe portion 3 is equal to the pressure difference Δ.
Since an appropriate measurement time of p is considered to be about 10 seconds to 10 minutes, the flow rate F during that period can be maintained. Further, in order to improve the measurement accuracy of the pressure difference Δp, the increase in the height ΔH of the powder fluidized bed 14 during the measurement time is preferably 5 cm or more, and more preferably in the range of 20 to 200 cm. Therefore, the height of the vertical pipe portion 3 needs to be set higher than the ΔH. Further, the inner diameter of the vertical tube portion 3 is preferably larger than 5 mm, more preferably in the range of 1 to 50 cm. Further, the introduction amount of the flowing gas 12 is, for example, the minimum fluidization speed Umf obtained by the following equation.
The superficial velocity of the vertical pipe section 3 is selected with reference to.

Umf = CmfGdp ² (ρs−ρg) / μ (5) Rep = dpUmfρg / μ (6) However, when Rep <1, Cmf = 6.05 × 10 ⁻⁴ R
When ep ^−0.0625 20 <Rep <600, Cmf = 2.20 × 10
^-3 Rep ^-0.555 where Umf = minimum fluidization rate (m / s) Rep = Reynolds number dp = particle diameter of powder 11 (m) ρs = particle density of powder 11 (kg / m ³ ) ρg = Density of flowing gas 12 (kg / m ³ ) μ = viscosity of flowing gas 12 (kg / m · s) The introduction amount of the flowing gas 12 is not less than this minimum fluidization speed Umf, but if it is too large, the powder 11 Since it will be blown away, it is preferable to set it in a range of 5 to 20 times Umf. Normally, the superficial velocity is often in the range of about 1 to 50 cm / s, but an appropriate flow velocity is obtained from the equation (5) depending on the characteristics of the powder particles. When an L-shaped pipe is used for the communication part 4, the flowing gas 13 is introduced into the horizontal part (see FIG. 1), and when a U-shaped pipe is used, the flowing gas 13 is introduced into the lower part of the rising part. (See FIG. 2) In the case of using a powder flow container, the flowing gas 13 is introduced into the lower part of the container (see FIG. 3). As a result, the powder 11 in the communication section 4 is fluidized and flows into the storage tank section 2. When measuring the flow rate, the introduction of the flowing gas 13 is stopped and the powder 11 in the communicating portion 4 is stopped, and the increase in powder accumulation in the vertical tube portion 3 is measured.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As an embodiment of the present invention, a flow rate measuring method in a circulating flow test apparatus according to the third invention will be described below in detail with reference to FIG. In this circulating flow tester,
As shown in FIG. 3, a communication is made up of a storage tank part 2, a rising pipe part 6, a vertical pipe part 3 having a cyclone 5 connected to the upper end thereof, and a powder flow container for connecting the lower end of the vertical pipe part 3 to the side surface of the storage tank part 2. The circulation type flow path 1C for the powder 11 is formed by sequentially connecting the portions 4 in a loop shape, and the differential pressure gauge 8 is connected between the pressure terminals 7 provided at the upper and lower portions of the vertical pipe portion 3. A pipe with an inner diameter of 10 cm and a height of 2 m is installed in the storage tank 2, and an inner diameter of 3 cm is installed in the vertical pipe 3.
× A tube with a height of 2 m, the rising pipe section 6 has an inner diameter of 3 cm and a height of 3 m
Each of the tubes is used. As the powder 11, 12 kg of alumina having a particle specific gravity of 1100 kg / m ³ and an average particle diameter of 55 μm was used. In addition, nitrogen gas was added to the lower portions of the vertical pipe portion 3 and the communication portion 4 as flowing gases 12 and 13, respectively.
Introduce 5 liters / minute, and flow gas 1 at the bottom of storage tank 2
Introducing 10 liters / min of air as No. 6 and 25 liters of nitrogen gas as the flowing gas 17 at the bottom of the rising pipe 2.
Minutes introduced.

In the above device, the powder 11 in the storage tank 2
Is fluidized by the flowing gas 16 and supplied to the lower portion of the rising pipe section 6, where it is transported by air flow by the flowing gas 17 to rise in the rising pipe section 6. The powder 11 that has risen is introduced into the cyclone 5 and separated from the gas, and then falls into the vertical pipe portion 3 below. On the other hand, the gas separated by the cyclone 5 is discharged upward. Powder 11 dropped on the vertical pipe section 3
Is fluidized by the flowing gases 12 and 13 and returns from the communication portion 4 into the storage tank portion 2. In this way, the powder 11 circulates in the flow path 1C.

In order to measure the circulating flow rate of the powder 11, the introduction of the flowing gas 13 into the communication part 4 is stopped to make the powder 11 in the communication part 4 stand still and to be formed on the upper and lower parts of the vertical pipe part 3. The pressure difference Δp between the powder fluidized bed 14 and the powder bed 15 was measured by the differential pressure gauge 8 (see FIG. 1), and this measurement was repeated a plurality of times. FIG. 4 is a diagram showing the measurement results, in which the horizontal axis represents the measurement time t (s) and the vertical axis represents the pressure difference Δp / g (kg /
m ² ) is taking. When the change amount d (Δp / g) / dt of this pressure difference Δp / g per unit time is read from the gradient of the diagram, it becomes d (Δp / g) /dt=1.73 kg / m ² · s. Moreover, since the inner diameter of the vertical pipe portion 3 is 3 cm,
The flow path area A is 7.065 × 10 ⁻⁴ m ² . Therefore, the circulation flow rate F of the powder 11 at this time is F = A · d (Δp / g) /dt=7.065×10 ⁻⁴ × 1.73 kg / s = 0.00122 kg / s.

[0016]

As described above, according to the first aspect of the present invention, the powder in the flow path is dropped from the upper end of the vertical pipe section provided in the powder flow path to the lower part of the vertical pipe section. By introducing a flowing gas, a powder fluidized bed and a powder bed are formed in the upper and lower parts of the vertical tube portion, and the change amount of the pressure difference between these two layers per unit time is measured to measure the particle in the flow path. Since it is configured to measure the flow rate, mechanical obstacles such as impact detection plate, slit container, etc. in the flow path of powder and strain such as the conventional impact powder flow meter and slit type powder flow meter There is no need to provide gauges, electronic detection terminals, etc. Therefore, the structure of the device is simple, there is no risk of mechanical destruction of powder particles or explosion, and even when the powder is hot or corrosive There is no need to use special materials for the parts.

Further, according to the second aspect of the invention, since the cyclone is connected to the upper end of the vertical pipe portion, even if the powder is air-transported in the flow path, the powder in the flow path is cycloned. The flow rate of the powder can be measured by the same method as in the first aspect of the invention by introducing the gas into the chamber and separating it from the gas, and then dropping the gas into the vertical tube.

Further, according to the third aspect of the invention, since the circulation flow rate of the powder which is pneumatically transported in the circulation type flow path can be measured, the powder is circulated between the ascending pipe portion and the descending pipe portion. While being in contact with gas, it can be used to measure the circulating flow rate of powder in a circulating fluidized bed that performs mass transfer operations such as catalytic reaction, solid-gas reaction, combustion, and drying, and is extremely useful for achieving the purpose of each operation. It is useful.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an apparatus used in a first invention.

FIG. 2 is an overall configuration diagram of an apparatus used in a second invention.

FIG. 3 is an overall configuration diagram of an apparatus used in the third invention and one embodiment thereof.

FIG. 4 is a diagram showing the measurement results of a differential pressure gauge obtained in an example of the third invention.

[Explanation of symbols]

 1A, 1B, 1C Flow path 2 Storage part 3 Vertical pipe part 4 Communication part 5 Cyclone 6 Rise pipe part 11 Powder 12 Fluid gas 13 Fluid gas 14 Powder fluidized bed 15 Powdered bed Δp Pressure difference

Claims (6)

[Claims] 1. A storage tank part (2) and a vertical pipe part (3) are provided in a flow path (1A) of powder (11), and a lower end of the vertical pipe part (3) is provided with a communication part (4). Through the side surface of the storage tank part (2) via the lower part of the vertical pipe part (3) while dropping the powder (11) in the flow path (1A) from the upper end of the vertical pipe part (3). And, by introducing the flowing gas (12, 13) into the communication part (4), the powder (11) that has fallen is fluidized and flowed into the storage tank part (2) from the communication part (4). After that, the introduction of the flowing gas (13) into the communication section (4) is stopped to make the powder (11) in the communication section (4) stand still, and at the same time, the vertical pipe section (3).
Powder fluidized bed (14) and powder bed (1)
5) Measuring the flow rate of the powder (11) in the flow path (1A) by measuring the amount of change in the pressure difference (Δp) with respect to 5) per unit time. Method. 2. A flow channel (1) for pneumatically transporting the powder (11).
B) is provided with a storage tank portion (2) and a vertical pipe portion (3), a cyclone (5) is connected to an upper end of the vertical pipe portion (3), and a lower end thereof is connected to the storage portion via the communication portion (4). The powder (11) in the flow path (1B) is introduced into the cyclone (5) and separated from the gas by communicating with the side surface of (2), and then the powder (11) is added to the vertical pipe portion. The powder (1) dropped by introducing the flowing gas (12, 13) into the lower part of the vertical pipe part (3) and the communication part (4) while being dropped to (3).
1) is fluidized to flow from the communication part (4) into the storage tank part (2), and then the powder (11) in the flow channel (1B) is measured by the flow rate measuring method according to claim 1. A method for measuring the flow rate of powder, characterized by measuring the flow rate. 3. A storage tank part (2), an ascending pipe part (6), a vertical pipe part (3) having a cyclone (5) connected to the upper end, and a lower end of the vertical pipe part (3) at the storage tank part (2). Of the powder (1
In the circulation channel (1C) of 1), the storage tank section (2)
The powder (11) therein is supplied from the lower part of the storage tank part (2) to the lower part of the rising pipe part (6) to raise the rising pipe part (6) by air flow, and the powder (11 ) Is introduced into the cyclone (5) to separate it from the gas, and then the powder (11) is dropped into the vertical pipe part (3) while the lower part of the vertical pipe part (3) and the communication part ( Flowing gas (1
Powder (11) dropped by introducing 2, 13)
Is fluidized to return from the communication part (4) to the inside of the storage tank part (2), and then the circulation flow rate of the powder (11) in the flow path (1C) is measured by the flow rate measuring method according to claim 1. A method for measuring the flow rate of powder, which comprises measuring. 4. The communication part (4) is an L-shaped tube,
2. The powder flow rate measuring method according to 2 or 3. 5. The communication part (4) is a U-shaped tube,
2. The powder flow rate measuring method according to 2 or 3. 6. The powder flow rate measuring method according to claim 1, 2 or 3, wherein the communicating portion (4) is a powder flow container.