JP2002162349A - Method and apparatus for monitoring gas-liquid two- phase flow - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus for monitoring a gas-liquid two-phase flow which can monitor conditions of mixed gas and liquid in the gas-liquid two-phase flow without contacting the liquid. SOLUTION: The apparatus comprises, a radiating means 63 for radiating a light from one side of the flowing liquid to another side, a light receiving means 64 for receiving the light on another side and a monitoring means 7 for monitoring strength of the light on another side as an element representing a mixed ratio of the gas and the liquid based on an output from the receiving means 64.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention, in the food and beverage plants, such as coffee plants, production (fill) N ₂ generated or mixed in the product liquid in the coffee liquid such in the process, CO ₂ gas such as air The present invention relates to a method and an apparatus for monitoring a gas-liquid two-phase flow for monitoring the same in an in-line liquid feed pipe.

[0002]

2. Description of the Related Art In a food and beverage plant, for example, a coffee plant, a coffee product liquid is stirred in a tank to contain air bubbles, or N ₂ gas or CO ₂ gas is generated and released from the product liquid, and this is generated as foam. And may remain in the product liquid.

[0003] In this case, the product liquid flows in a liquid-gas two-phase fluid state in a liquid sending pipe for sending the product liquid to the filling machine. When the product liquid enters the two-phase flow state in the liquid supply pipe,
Indicated values of instruments such as a liquid meter and a pressure gauge in the filling machine become inaccurate. That is, in general, the filling amount of the product liquid in the container is measured by a positive displacement type liquid meter, and when the product liquid is in a two-phase flow state, the liquid meter also measures and fills the gas. However, there arises a problem that the flavor (net filling amount) is insufficient. Since the above-mentioned inconvenience occurs in a place where it cannot be visually observed, it will become apparent when the final product is inspected by inspection. Therefore, when the above-mentioned problem occurs, the yield of products is significantly reduced.

[0004]

As described above, in a coffee plant or the like, when air, N2 gas, or the like is mixed in a product liquid flowing through a liquid feed pipe, the net filling amount of the product liquid is reduced. The problem of shortage occurs. Therefore, there is a need for a means for constantly monitoring the flow of the product liquid in the state of the two-phase fluid in the liquid feed pipe without directly contacting the product liquid. However, such means is still required. Not proposed.

An object of the present invention is to provide a method and apparatus for monitoring a gas-liquid two-phase flow that can monitor the gas-liquid two-phase flow without contacting the liquid in view of the above situation.

[0006]

According to the present invention, there is provided a method for monitoring a gas-liquid two-phase flow, comprising projecting light from one side of a flowing liquid toward the other side; Monitoring the light intensity as an element indicative of the gas-liquid mixing ratio. In this monitoring method, it is possible to use visible light as the light to be projected. Further, this monitoring method can be applied to monitoring of a beverage flowing through a liquid feeding pipe of a food plant. The gas-liquid two-phase flow monitoring device according to the present invention is a light projecting unit that projects light from one side of the flowing liquid toward the other side, and a light receiving unit that receives the light at the other side, Monitoring means for monitoring the light intensity on the other side as an element indicating the gas-liquid mixing ratio based on the output of the light receiving means. In this monitoring device,
When the light projected from the light emitting means is not a parallel light,
A lens for converting the light into parallel light can be provided. In this monitoring device, a slit for adjusting a cross-sectional shape of the light projected from the light projecting means can be provided.
Further, in this monitoring device, by providing comparison means for comparing the intensity of light received by the light receiving means with a preset reference intensity, the degree of the gas-liquid mixing ratio can be recognized in a binary manner. it can.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The method and apparatus for monitoring a gas-liquid two-phase flow according to the present invention are applied to, for example, a coffee liquid filling plant shown in FIG. In the following, the gas is N
_Although the case of _two gases will be described, the same monitoring method and apparatus can be applied to CO ₂ gas. As shown in FIG. 1, the coffee beverage filling plant has a configuration in which a liquid feed pipe 3 is interposed between a coffee extraction blending tank 1 and a filling machine 2.

The filling machine 2 includes an annular liquid chamber 21 rotatably supported, a rotary joint 22 interposed between the liquid chamber 21 and the liquid supply pipe 3, and a bottom circumferential direction of the liquid chamber 21. And a number of filling valves 23 arranged at predetermined intervals.

The gas-liquid two-phase flow monitoring device 5 according to the present invention comprises:
It has a detection unit 6 provided at a position near the filling machine 2 in the liquid sending pipe 3, and a controller 7 connected to the detection unit 6. FIG.
3 shows an enlarged cross-sectional view of the detection unit 6, and FIG. 3 shows a cross-sectional view taken along line AA of FIG. As shown in these drawings, the detection unit 6 is provided with a light-transmitting cylinder 62 coaxially interposed in the middle of the liquid sending pipe 3 via a support member 61 fitted to both ends, and sandwiches the light-transmitting cylinder 62. A light emitting element 63 and a light receiving element 64 opposed to each other, and a slit 65 a on the optical axis of the light emitting element 63.
And a condenser lens 66 for collimating the light emitted from the light emitting element 63. When the light emitting element 63 emits parallel light, the condenser lens 66 can be omitted.

The light-transmitting cylinder 62 is formed of a material such as glass or resin having a light-transmitting property, and the cross-sectional shape of the liquid-feeding pipe 3 is set so as not to disturb the passage of the coffee liquid passing therethrough. Is approximated. It is desirable that opposing wall portions through which light passes are parallel to each other.

The support 61 holds the light transmitting cylinder 62 so that its inner peripheral surface is aligned with the inner peripheral surface of the light transmitting cylinder 62, and is watertightly connected to the liquid feed pipe 3 via a flange joint 61a and a packing 61b. I have. Note that a union joint may be used instead of the flange joint. As the light emitting element 63, a light source capable of stably emitting visible light having a constant intensity, such as a light emitting diode, is used. The light projected from the light emitting element 63 is made parallel by the condenser lens 66, and
After being modified to have an appropriate cross-sectional shape through the slit 65 a of the hood 65, it passes through the parallel wall portion of the light transmitting cylinder 62. Note that the controller 7 supplies power for light emission to the light emitting element 63 via the power supply line 63a.

The light receiving element 64 receives all the light that has passed through the light transmitting tube 62, converts the light into a voltage corresponding to the intensity thereof, and outputs the voltage. For example, a photocell is used. The output signal of the light receiving element 64 is a signal line 64a.
To the controller 7 via The controller 7 has a built-in microprocessor.

The operation of the gas-liquid two-phase flow monitoring device 5 will be described below. The coffee liquid stored in the coffee extraction / mixing tank 1 is pumped to the liquid sending pipe 3 by the pump 8. Then, the coffee beverage is supplied to the liquid chamber 21 via the rotary joint 22 of the filling machine 2 and then filled into the container 9 via the filling valve 23.
The filling amount of the coffee beverage into the container 9 is measured by a measuring means (not shown). As described above, when the coffee beverage contains bubbles, the measured value of the filling amount has an error. And the problem that the net filling amount of the beverage in the container 9 becomes insufficient occurs.

Therefore, the monitoring device 5 provided in the liquid sending pipe 3 monitors the mixing ratio of the gas and the liquid flowing in the light transmitting cylinder 62 at predetermined time intervals. Here, the principle of the measurement of the mixing ratio will be described first. Since the light intensity I is exponentially attenuated when passing through another substance, it can be generally expressed by the following equation as an exponential function of the light transmission distance S. I = I ₁ exp (−μS) (1) where I ₁ : intensity of light at entrance position (position of slit 65a) μ: constant determined by substance (attenuation rate)

Now, ignoring the effect of the wall of the light transmitting cylinder 62 and assuming that the distance between the inner walls of the light transmitting cylinder 62 is S ₂ , the exit position when only N ₂ gas flows (the light transmitting cylinder 62 is (Extracted position)
The light intensity I _N2 in the light intensity I _C2 at the exit position when a current of coffee liquid only, are expressed as follows. I _N2 = I ₁ exp (−μ _N S ₂ ) (2) where μ _N : attenuation rate of N ₂ gas I _C2 = I ₁ exp (−μ _C S ₂ ) (3) Where μ _C : attenuation rate of coffee liquid

The liquid becomes a two-phase fluid. At this time, the thickness of the N ₂ gas (light passing distance) is S _N , and the thickness of the coffee liquid is S
If _{C, the} light intensity I _D2 at the outlet _{position, I D2 = I 1 exp (} -μ N S N) exp (-μ C S C) = I 1 exp (-μ N S N -μ C S C ) (4)

Then, since there is a relationship of S ₂ = S _N + S _C , the above equation (4) gives I _D2 = I ₁ exp (−μ _N (S ₂ −S _C ) −μ _C S _C ) = I _{1 exp (-μ N S 2 -} (μ C -μ N) S C = I 1 exp (-μ N S 2) exp (- (μ C -μ N) S C) = I N2 exp (- (μ _{C -μ N) S C) ···} (5) _{or, I D2 = I C2 exp (} -. denoted _{(μ N + μ C) S} N) ··· (5) ' Thus, I _1, μ _{If N} and μ _C are known, the thickness S _{C of the} coffee liquid can be obtained by measuring I _D2.
And N ₂ gas having a thickness of S _N, as well as to know the mixing ratio S _N / S _C of the coffee solution and N ₂ gas.

FIG. 4 shows the light intensity I with respect to the light transmission distance S.
3 is a diagram illustrating an example of the attenuation characteristic. As shown in this diagram, the light intensity I _N when only N ₂ gas is flowing gradually attenuated from the entrance light intensity I ₁ to the exit light intensity I _N2 , and the N ₂ gas and coffee were mixed. The light intensity I _D for the two-phase flow attenuates from the entrance light intensity I ₁ to the exit light intensity I _D2 which is lower than the light intensity I _N2 .
And the light intensity I _C when only coffee is distributed
Attenuates from the entrance light intensity I ₁ to the exit light intensity I _C2 which is still lower than the light intensity I _D2 .

As is apparent from this diagram, 2
The outlet intensity I _D2 for the phase flow will vary depending on the mixture ratio of the coffee liquid and the N ₂ gas. In other words, the outlet intensity I _D2 is a suggestive element mixing ratio of the coffee solution and N ₂ gas. The light intensity I _D2 measured by the detection unit 6 is sent to the controller 7 as information indicating the mixture ratio of the coffee liquid and the N ₂ gas. Therefore, the controller 7
The light intensity I _D2 is compared with a preset threshold value I _TH, and I _D2
In case of> _ITH , it outputs signals necessary for issuing an alarm or stopping the line.

The controller 7 calculates an accurate value of the mixing ratio based on the exit light intensity I _D2 obtained from the output of the light receiving element 64 and the equations (5) and (5) ′. Alternatively, the mixture ratio may be compared with an appropriate threshold. However, it is sufficient to compare the light intensity I _D2 with the threshold value I _TH only to determine the occurrence of a defect such as a shortage of the net filling amount. This makes the arithmetic processing in the controller 7 easier. In practicing the present invention, I
₁ , I _N2 and I _C2 are measured in advance. Further, the threshold I
_TH is appropriately set by experiments and the like.

The monitoring method and apparatus according to the above embodiment are applied to monitoring of a gas-liquid two-phase flow, but can also be applied to monitoring of a liquid-liquid two-phase flow. However, when applied to the monitoring of the liquid-liquid two-phase flow, the two liquids need to have greatly different attenuation rates.

[0022]

According to the present invention, at least the following effects can be obtained. (1) If applied to coffee plants that handle liquids,
Since the amount of gas generated or mixed in the liquid flowing in the liquid supply pipe can be continuously monitored in-line, it contributes to automation of operation and stability of product quality. (2) Since visible light can be used as the light to be projected, it is possible to facilitate the handling and reduce the implementation cost. (3) The device can be monitored without coming into contact with the liquid, and the maintenance of the device is easy.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a coffee plant to which the present invention is applied.

FIG. 2 is an enlarged sectional view of a main part of a detection unit of the gas-liquid two-phase flow monitoring device according to the present invention.

FIG. 3 is a sectional view taken along line AA of FIG. 2;

FIG. 4 is a diagram illustrating an attenuation characteristic of a light intensity I with respect to a light passing distance S;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Extraction / mixing tank 2 Filling machine 22 Rotary joint 23 Filling valve 3 Liquid sending pipe 5 Monitoring device 6 Detector 62 Translucent cylinder 63 Light emitting element 64 Light receiving element 65 Hood 7 Controller

Claims (7)

[Claims] 1. A step of projecting light from one side of a flowing liquid toward another side, and a step of monitoring the intensity of the light on the other side as an element indicating a gas-liquid mixing ratio. A method for monitoring gas-liquid two-phase flows. 2. The method for monitoring a gas-liquid two-phase flow according to claim 1, wherein visible light is used as the light to be projected. 3. The method for monitoring a gas-liquid two-phase flow according to claim 1, wherein the liquid is a beverage flowing through a liquid feeding pipe of a food plant. 4. A light projecting means for projecting light from one side of the flowing liquid toward another side, a light receiving means for receiving the light on the other side, and the light receiving means based on an output of the light receiving means. Monitoring means for monitoring the light intensity on the other side as an element indicating the gas-liquid mixing ratio. 5. The gas-liquid two-phase flow monitoring device according to claim 4, further comprising a lens for converting light projected from said light projecting means into parallel light. 6. The gas-liquid two-phase flow monitoring device according to claim 4, wherein a slit for adjusting a sectional shape of the light projected from the light projecting means is provided. 7. The air monitor according to claim 4, wherein said monitoring means includes a comparing means for comparing the intensity of the light received by said light receiving means with a preset reference intensity. Monitoring device for liquid two-phase flow.