JP2010207724A - Gas dissolving system, gas dissolving method, and gas dissolving program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas dissolving technology capable of dissolving gas in liquid in a desired amount of gas dissolving by supplying a proper amount of gas. <P>SOLUTION: The gas dissolving system (1) includes a liquid supplying path (20) that supplies the liquid, a gas supplying path (12) that supplies the gas, a dissolving section (15) that dissolves the gas in the liquid, a flow measuring section (22) that measures the flows of the liquids upstream the dissolving section, a temperature measuring section (21) that measures the temperature of the liquid upstream the dissolving section, a computing section (30) that computes an amount of the gas required to dissolve the gas in the liquid based on the measured flow of the liquid and gaseous saturation solubility characteristics to the measured liquid temperature, and a gas flow controlling section (13) that controls the flow of the gas so as to allow the gas to be supplied in the required amount of the gas and is provided in the gas supplying path upstream the dissolving section. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a gas dissolving apparatus that dissolves a gas into a liquid, and more particularly to a technique that can supply a gas without excess or deficiency and dissolve a saturated amount of gas in the liquid.

  Conventionally, an oxygen dissolving apparatus capable of increasing the amount of dissolved oxygen in water has been proposed. For example, in Japanese Patent Application Laid-Open No. 2004-089968, as shown in FIG. 1, when a gap is provided in the pipe wall of the water pipe so as to communicate the inside and outside of the pipe, oxygen is supplied to the outside of the gap. An oxygen dissolving device is disclosed in which the pressure is adjusted to be relatively lower than the water supply pressure inside the gap. Oxygen has an oxygen container 30 that covers the outside of the gap so as to form an oxygen chamber 36, and an oxygen supply pipe 92 b that sends oxygen to the oxygen chamber 36. Further, in the middle of the oxygen supply pipe 92b, there are provided a relay tank 80, an air-out at the downstream position of the gap in the water supply pipe, and a recovery pipe 73 that is piped from the air-out to the relay tank 80. With such a minor configuration, an oxygen dissolving apparatus that does not require power and can obtain high dissolving performance has been provided.

JP 2004-089968 A

  However, the conventional oxygen dissolving apparatus does not adjust the supply amount of oxygen, which causes various inconveniences. For example, when the amount of oxygen supplied is too small, a saturated amount of oxygen could not be dissolved. On the other hand, when the supply amount of oxygen was too large, oxygen that had not exceeded the saturation dissolution amount and was not dissolved had to be exhausted.

  Accordingly, one of the objects of the present invention is to provide a gas dissolution technique capable of supplying an appropriate amount of gas and dissolving the gas in the liquid with a desired gas dissolution amount.

  In general, the amount of saturated dissolution in a gas liquid depends on the temperature and pressure of the liquid. And as the amount of liquid increases, the amount of gas supply must also increase. In view of this, the supply of gas without excess or deficiency cannot be maintained unless the gas supply amount is controlled in consideration of these factors that can change every moment. The inventor of the present application has realized that the present invention must be considered in order to supply the gas without excess or deficiency and dissolve it in the liquid.

In order to solve the above problems, a gas dissolution system according to the present invention is a gas dissolution system for dissolving a gas into a liquid, the liquid supply path supplying the liquid, and the gas supply path supplying the gas. A dissolving part for dissolving the gas in the liquid; a flow rate measuring part for measuring the flow rate of the liquid upstream of the dissolving part; and a temperature measuring part for measuring the temperature of the liquid upstream of the dissolving part; A calculation unit that calculates a necessary gas flow rate for dissolving the gas in the liquid based on the measured flow rate of the liquid and a saturation solubility characteristic of the gas with respect to the measured temperature of the liquid; A gas flow rate control unit provided in the gas supply path on the upstream side of the dissolution unit, which controls the flow rate of the gas so that the gas is supplied at a necessary gas flow rate.
Note that, as described above, the saturation solubility of a gaseous liquid is affected by the pressure of the liquid in addition to the temperature of the liquid. In the calculation of the above system, the pressure is constant and a fixed value is used.

The gas dissolution method of the present invention is also a gas dissolution method including the following steps for dissolving a gas in a liquid.
a) measuring the flow rate of the liquid;
b) measuring the temperature of the liquid;
c) calculating a gas flow rate required to dissolve the gas in the liquid based on the measured flow rate of the liquid and the saturation solubility characteristic of the gas with respect to the measured temperature of the liquid;
d) controlling the flow rate of the gas so that the gas is supplied at the required gas flow rate; and e) dissolving the gas supplied at the required gas flow rate in the liquid.
In the calculation of the above method, the pressure is constant and a fixed value is used.

The gas dissolution program of the present invention is a gas dissolution program for dissolving a gas in a liquid, and is also a gas dissolution program for causing a computer to execute the following functions.
a) a function of inputting the flow rate of the liquid;
b) a function of inputting the temperature of the liquid;
c) a function of calculating a necessary gas flow rate for dissolving the gas in the liquid based on the input flow rate of the liquid and the saturation solubility characteristic of the gas with respect to the input temperature of the liquid; and d ) A function of controlling the flow rate of the gas so that the gas is supplied at the required gas flow rate.
In the calculation of the above program, the pressure is constant and a fixed value is used.

  As described above, the saturation dissolution amount of a gaseous liquid depends on the temperature and pressure of the liquid. If the saturation solubility characteristics of the gas to be dissolved in the liquid are grasped and the pressure is constant, the saturated solubility of the gas in the liquid at the measured temperature, that is, the measured temperature, is measured. The amount of gas that can be dissolved in a unit weight or volume of liquid at a temperature can be grasped. The gas flow rate required to dissolve a gas in a liquid at a specific saturation solubility can be calculated based on the saturation solubility for the measured temperature and the flow rate of the liquid in which the gas is to be dissolved.

  According to this invention, since the saturated solubility characteristics of the gas are stored so as to be able to be referred to, the temperature and flow rate of the liquid are measured and dissolved at the measured liquid temperature to the maximum unit weight or volume of the liquid. Can determine the flow rate (or weight) of gas that can be saturated, that is, the saturation solubility at that temperature, and the maximum flow rate (or weight) of gas that can be dissolved relative to the flow rate of the supplied liquid can be calculated . Therefore, according to the present invention, it is possible to supply a gas flow rate sufficient to dissolve the gas in the liquid with the saturation solubility at the measured temperature of the liquid. For this reason, it is possible to prevent excessive gas from being supplied and exhausted without dissolving in the liquid, and waste of expensive gas. In addition, it is possible to prevent the disadvantage that a small amount of gas is supplied for dissolution with saturation solubility, and the gas cannot be dissolved in the liquid to the maximum extent.

The present invention may further include the following elements as desired.
1-1) In the gas dissolution system of the present invention, the gas dissolution system further includes a pressure measurement unit that measures the pressure of the liquid upstream of the dissolution unit, and the calculation unit measures the measured flow rate of the liquid and The required gas flow rate is calculated based on the saturation pressure characteristic of the gas with respect to the pressure of the liquid and the measured temperature of the liquid.

1-2) A gas dissolution program for dissolving a gas in a liquid, and causing the computer to execute the following functions.
a) a function of inputting the flow rate of the liquid;
b) a function of inputting the temperature of the liquid;
c) a function of inputting the pressure of the liquid;
d) Necessary gas for dissolving the gas in the liquid based on the input flow rate of the liquid and the saturated solubility characteristic of the gas with respect to the input pressure of the liquid and the input temperature of the liquid. A function of calculating the flow rate; and e) a function of controlling the flow rate of the gas so that the gas is supplied at the required gas flow rate.

  As described above, the saturation solubility of a gaseous liquid is affected by the pressure of the liquid in addition to the temperature of the liquid. According to this invention, since the required gas flow rate is calculated using the saturation solubility characteristic measured based on the pressure of the liquid in addition to the temperature of the liquid, the calculated gas flow rate can be supplied more accurately.

  2) In the gas dissolving system of the present invention, the dissolving portion includes a sintered metal filter, and the gas is dispersed in the liquid by the sintered metal filter to dissolve the gas in the liquid.

  The sintered metal filter is a member obtained by baking and solidifying metal powder at a temperature around the melting point, and is a member for removing impurities by circulating a liquid or gas through the sintered metal. In the sintered metal filter, since a fine flow path is complicatedly formed in the sintered metal, it is possible to disperse the gas as fine bubbles in the liquid. That is, when a liquid is brought into contact with one end of a sintered metal filter and a gas to be dissolved from the other end is supplied at a predetermined pressure, the gas becomes bubbles dispersed by the sintered metal, resulting in a significant increase in the surface area where the gas and the liquid are in contact with each other. And the gas is easily dissolved in the liquid. According to this invention, since the dissolving part includes the sintered metal filter, the gas supplied at the required gas flow rate can be dissolved in the liquid without excess or deficiency.

  3) In the gas dissolution system of the present invention, the calculation unit is configured to be able to arbitrarily set the solubility of the gas in the liquid, and the calculation unit is configured such that the set gas solubility is the saturation of the gas. When it is determined that the solubility is equal to or lower than the solubility, the flow rate of the gas necessary for dissolving the gas in the liquid with the gas solubility is calculated as the required gas flow rate.

  If it is below saturation solubility, the amount of gas dissolved in the liquid can be adjusted by adjusting the flow rate of the gas. According to this invention, when the solubility is below the saturation solubility, the gas flow rate required for dissolving the gas in the liquid with the designated solubility is calculated, and the gas is supplied at the required gas flow rate. The gas can be dissolved in the liquid with the solubility of.

  4) In the gas dissolution system according to the present invention, when the calculation unit determines that the set gas solubility exceeds the saturation solubility of the gas, the gas has the saturation solubility of the gas as the required gas flow rate. The flow rate of the gas necessary for dissolving the gas in the liquid is calculated.

  No matter how much gas is supplied in excess of the gas flow rate required to reach the saturation solubility, it is not possible to dissolve a larger amount of gas than the saturation solubility in the liquid. According to this invention, when the set solubility exceeds the saturation solubility, the necessary gas flow rate for the saturation solubility is supplied, so that waste of gas can be prevented.

  According to the present invention, since an appropriate amount of gas is supplied based on the measured liquid flow rate and the saturation solubility characteristic with respect to the measured liquid temperature, excess gas is supplied to waste the gas. It is possible to prevent inconveniences such as exhausting or insufficient gas supply to reach the expected gas dissolution amount.

The system block diagram of the gas dissolution system of Embodiment 1. FIG. Temperature-saturated solubility characteristics for gaseous liquids. The flowchart explaining the gas dissolution method (the 1) of Embodiment 1. FIG. The system block diagram of the gas dissolution system of Embodiment 2. FIG. The density | concentration characteristic figure of the gas melt | dissolved in the liquid with respect to a liquid (gas) pressure. Temperature and pressure-saturation solubility characteristics for gaseous liquids. The flowchart explaining the gas dissolution method (the 2) of Embodiment 2. FIG. The system block diagram of the gas dissolution system of Embodiment 3. FIG. The flowchart explaining the gas dissolution method (the 3) of Embodiment 3. FIG.

  Embodiments of the present invention will be described below. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, the drawings are schematic. Therefore, specific dimensions and the like should be determined in light of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

(Embodiment 1)
The first embodiment of the present invention measures the temperature of the liquid and the flow rate of the liquid, calculates a necessary gas flow rate for dissolving the gas in the liquid based on them, and controls the gas to be supplied at the flow rate. It relates to the invention to do.

(System configuration)
FIG. 1 shows a system configuration diagram of a gas dissolution system in the first embodiment.
As shown in FIG. 1, the gas dissolving system 1 according to the first embodiment includes a gas tank 10, a main valve 11, a gas supply path 12, a mass flow controller 13, a check valve 14, and a dissolving unit as a gas supply system configuration. 15 is provided. The gas dissolution system 1 includes a liquid supply path 20, a liquid temperature sensor 21, a liquid flow rate sensor 22, and a liquid discharge path 25 as a configuration of the liquid supply system. Furthermore, the gas dissolution system 1 includes a control unit 30 that controls various components such as the main valve 11, the gas supply path 12, and the mass flow controller 13.

  The gas that can be used in the present invention can be arbitrarily selected. Any gas having temperature dependency in solubility in a liquid can be used as the target gas of the present invention. For example, industrially or commercially available gases such as hydrogen, helium, nitrogen, carbon dioxide, oxygen, hydrogen chloride, ammonia, etc. can be applied.

  Similarly, the liquid that can be used in the present invention can be arbitrarily selected, but at least it must be a liquid that can dissolve the gas to be used. As the liquid, water is typically used, but other solutions such as alcohols, solvents, and solutes depending on the purpose of use may also be used.

First, the configuration of the gas supply system will be described.
The gas tank 10 is a storage unit that stores gas at a high pressure, and various gas storage structures can be used. The main valve 11 is configured to be able to supply or block gas from the gas tank 10 to the gas supply path 12. The gas supply path 12 is a pipe that forms a flow path through which gas flows. The gas supply path 12 may be provided with a regulator (pressure regulating valve) (not shown) so as to supply a gas having a constant pressure.

The mass flow controller 13 corresponds to the gas flow rate control unit of the present invention, and includes a thermal flow sensor and a solenoid valve. The mass flow controller 13 receives a flow command signal C _Q from the control unit 30 controls the solenoid valve while detecting the flow rate of the gas flowing through the gas supply passage 12 by the thermal flow sensor, a flow rate command signal C _Q Control the gas to flow at the commanded flow rate. However, the structure and function of the mass flow controller are not limited as long as the flow rate of the gas can be controlled to some extent accurately.

  The check valve 14 is configured to be able to prevent the liquid from flowing backward from the downstream side to the gas supply path 12 side. As a safety measure for preventing backflow, the check valve 14 is simple and preferable, but is not an essential component. For example, if the pressure of the gas supply path 12 can be appropriately controlled and there is little risk that the liquid flows backward, the check valve 14 may not be provided.

  The dissolution unit 15 is configured to dissolve the gas supplied from the gas supply path 12 into the gas supplied from the liquid supply path 20 and discharge the gas to the liquid discharge path 25. The structure of the dissolving portion 15 is not limited, but it is preferable that the dissolving portion 15 has a structure capable of efficiently promoting the dissolution of the gas into the liquid by expanding the area where the gas and the liquid are in contact as much as possible. For example, a sintered metal filter is preferably used as the dissolving portion 15.

  The sintered metal filter is obtained by baking and solidifying metal powder at a temperature around the melting point, for example, by melting bronze sphere powder, SUS (stainless steel) deformed powder, SUS sphere powder, and the like. Yes. The sintered metal filter is configured such that the size of the gap formed between the welded powders can be adjusted by adjusting the size of the metal powder constituting the filter. The sintered metal filter can be used for applications such as filtering impurities from a liquid or gas to be permeated, removing a gas component from a liquid or solid, or diffusing the gas evenly. Since this sintered metal filter has a complicated flow path in the sintered metal, it can disperse the gas as fine bubbles in the liquid and increase the contact area between the gas and the liquid. This is suitable as the structure of the dissolving portion 15 of the present invention.

Next, the configuration of the liquid supply system will be described.
The liquid supply path 20 is a pipe that forms a flow path through which liquid flows. In the case of using a publicly supplied liquid such as water as the liquid of the present invention, the liquid supply path 20 may be configured to draw water from a public water supply facility. When liquids other than water are used as the liquid of the present invention, the liquids are stored in a storage tank, and the liquid is supplied from the storage tank to the liquid gas supply path 12. The liquid supply path 20 may be provided with a control valve (not shown) as necessary.
The liquid temperature sensor 21 corresponds to the temperature measurement unit of the present invention, and is configured to be able to detect the temperature of the liquid flowing through the liquid supply path 20. The liquid temperature sensor 21 is configured to detect the temperature of the liquid and output a temperature detection signal _ST to the control unit 30. Since the temperature of the liquid in the place where the gas is dissolved should be detected, the liquid temperature sensor 21 is preferably installed as close as possible to the dissolving portion 15.
The liquid flow rate sensor 22 corresponds to the flow rate measurement unit of the present invention, and is configured to be able to measure the flow rate (volume) of the liquid flowing through the liquid supply path 20. The liquid flow rate sensor 22 is configured to detect the flow rate of the liquid and output a flow rate detection signal _SQ to the control unit 30. The liquid flow sensor may be any sensor that can detect the flow rate of the liquid. For example, a flow meter based on various measurement principles such as an electromagnetic flow meter, a differential pressure flow meter, an annual flow meter, a venturi flow meter, a vortex flow meter, etc. Is available. If the cross-sectional area S of the liquid supply path 20 is known, the flow rate Q (= S × V) of the liquid can be grasped by measuring the flow velocity V of the liquid. It may be replaced with.

  As shown in FIG. 1, the liquid supply path 20 is connected to the dissolving portion 15 at a branch point 24. In the dissolving portion 15, the gas and the liquid come into contact with each other at a constant pressure, and as a result of the gas becoming fine bubbles and diffusing into the liquid, the gas is dissolved in the liquid, And is discharged from the liquid discharge path 25.

  The control unit 30 is a computer device corresponding to the calculation unit of the present invention, and includes a CPU, a ROM, a RAM, a non-volatile memory, and various interface devices (not shown). The control unit 30 is equipped with the gas dissolution program of the present invention, and is configured to execute the gas dissolution method of the present invention by executing the program. In particular, the control unit 30 stores temperature-saturated solubility characteristics described later as a data table. The control unit 30 is not necessarily arranged in the vicinity of the liquid temperature sensor 21, the liquid flow rate sensor 22, and the mass flow controller 13, and may be a remote operation device arranged in a remote place.

(Description of operation)
Next, the operation of the gas dissolution system 1 will be described with reference to the drawings.
FIG. 2 shows a saturation solubility characteristic (curve) with respect to the temperature of the liquid. FIG. 2 illustrates a saturated solubility characteristic q1 for the gas 1, a saturated solubility characteristic q2 for the gas 2, and a saturated solubility characteristic q3 for the gas 3, respectively. It is assumed that the pressure is constant. As shown in FIG. 2, when the pressure is constant, the solubility of the gas changes depending on the temperature. The dissolution of gas is an exothermic reaction. The higher the temperature, the more difficult the gas dissolves in the liquid, and the lower the temperature, the easier the gas dissolves in the liquid. This tendency is the same regardless of the type of gas.

  As shown in FIG. 2, when the pressure is constant, the saturation solubility is uniquely determined by specifying the gas to be dissolved and the liquid to be dissolved. Therefore, if the temperature-saturation solubility characteristic is known, the saturation solubility at that temperature can be specified even if the temperature changes. Saturated solubility is expressed as the volume of gas relative to the unit volume or unit weight of liquid. It can be seen that the flow rate (volume) of the gas that dissolves the constant flow rate (volume) with the saturation solubility can be easily calculated based on the specified saturation solubility and the flow rate of the supplied liquid.

In the first embodiment, the control unit 30 stores temperature-saturated solubility characteristics measured for the gas and liquid to be used on the assumption that the system pressure hardly changes. Then, calculates the required gas flow Qreq based on the temperature T _L of the liquid indicated by the temperature detection signal S _T inputted from the liquid temperature sensor 21, the required gas flow Qreq controls the mass flow controller 13 to supply To work.

Specifically, a case is considered where the saturated solubility _{DT of the} gas is obtained by referring to the temperature-saturated solubility characteristics based on the measured liquid temperature _TL . Saturation solubility because indicates the weight of the gas can be dissolved per unit volume (unit weight) (e.g., grams or moles), necessary gas weight W _A based on the measured liquid flow Q _L, equation (1) Is obtained.
W _A = Q _L × D _T (1)
For example, if the number of moles of gas is known, the volume of gas (that is, the required gas flow rate) V can be calculated by equation (2).
V = nRT / P (2)
(However, the pressure applied to the liquid is P [Pa], the volume is V [m ³ ], the number of moles of gas is n [mol], the gas constant is R [J / (mol · K)], and the absolute temperature is T ( K).)

  The temperature-saturated solubility characteristic can be obtained by measuring the volume of gas dissolved per unit volume of liquid used in the gas dissolution system 1 while changing the temperature. About some gas, since temperature-saturated solubility characteristic is published in the chemical handbook etc., you may utilize it.

Further, the temperature dependency of the saturation solubility of gas can be approximated by a predetermined relational expression as expressed by the equation (3).
LogD = a / T + bxT + cxLogT + d (3)
(Where D: solubility [w / wt%], T = (t (temperature [° C.]) + 273.15), a, b, c, d: constant)

  Furthermore, the solubility of a gas can be expressed by an Ostwald solubility constant, a Bunsen absorption constant, or the like. Therefore, instead of the data table of the saturation solubility characteristic, the saturation solubility may be directly calculated from the temperature measured based on such a relational expression.

  Next, a specific operation of the gas dissolution system 1 will be described with reference to the flowchart shown in FIG. The gas dissolving method 1 based on the flowchart is performed by the control unit 30 shown in FIG. 1 executing a predetermined gas dissolving program.

In step S <b> 101, the control unit 30 determines whether it is time to execute the gas dissolving method 1 of the first embodiment. If it is not the execution timing (NO), the process returns. If it is determined that the execution timing of the gas dissolution method 1 (YES), the process proceeds to step S102, the control unit 30, flows through the liquid supply passage 20 based on the detected flow rate signal S _Q inputted from the liquid flow sensor 22 The liquid flow rate Q _L to be measured is measured. Then the process proceeds to step S103, the control unit 30 refers to the temperature detection signal S _T inputted from the liquid temperature sensor 21 measures the nearest liquid temperature T _L.

Then the process proceeds to step S104, the control unit 30, a temperature - with reference to the saturation solubility characteristics, to identify the saturation solubility D _T of the gas in the measured fluid temperature T _L. Then the process proceeds to step S105, the control unit 30, the gas required for dissolving at the saturation solubility D _T to the liquid gas on the basis of the saturation solubility D _T and the measured liquid flow Q _L in step S102 flow rate ( The required gas flow rate Qreq) is calculated.

Shifts required gas flow Qreq steps S106 Once calculated, the control unit 30, the flow rate of the gas supplied to the dissolution unit 15 outputs a flow command signal C _Q for required gas flow Qreq the mass flow controller 13. The mass flow controller 13, based on this flow command signal C _Q and adjust the flow rate of the gas, the gas which has been adjusted to the required gas flow Qreq is supplied to the melting zone 15. In the dissolving part 15, this gas is dispersed in the liquid as fine bubbles. At this time, the gas flow rate is adjusted to a necessary gas flow rate Qreq necessary and sufficient to dissolve the gas in the liquid with the saturation solubility, so that the gas can be dissolved in the liquid without excess or deficiency.

As described above, the gas dissolution system according to Embodiment 1 has the following advantages.
1) According to the first embodiment, on the basis of the temperature-saturated solubility characteristic measured and stored in advance, the gas flow rate necessary and sufficient to dissolve the gas in the liquid at the saturated solubility at the measured liquid temperature is obtained. Can be supplied. Therefore, it is possible to prevent inconvenience that gas is supplied at an excessive flow rate and exhausted without dissolving in the liquid to waste expensive gas, or gas is supplied at a low flow rate and does not reach saturation solubility.

  2) According to the first embodiment, since the dissolving portion 15 includes the sintered metal filter, it is possible to greatly increase the surface area where the gas and the liquid are in contact with each other and efficiently dissolve the gas in the liquid. .

  3) According to the first embodiment, since the control unit 30 is configured to store and refer to the temperature-saturated solubility characteristics as a data table, the temperature-saturated solubility is changed when the gas and liquid to be used are changed. By changing to the data table indicating the characteristics, it can be easily applied to a system that handles different types of gases and liquids.

(Embodiment 2)
In Embodiment 2 of the present invention, the pressure of the liquid is measured in addition to the temperature of the liquid and the flow rate of the liquid, and a necessary gas flow rate for dissolving the gas in the liquid is calculated based on them. The present invention relates to an invention for controlling to be supplied. The same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted as appropriate.

The system block diagram of the gas dissolution system 1b in this Embodiment 2 is shown in FIG.
As shown in FIG. 4, the gas dissolution system 1 b according to the second embodiment includes a gas tank 10, a main valve 11, a gas supply path 12, a mass flow controller 13, a check valve 14, and a dissolution unit as a gas supply system configuration. 15 is provided. The liquid supply system includes a liquid supply path 20, a liquid temperature sensor 21, a liquid flow rate sensor 22, a liquid pressure sensor 23, and a liquid discharge path 25.
The gas dissolving system 1b of the second embodiment is different from the first embodiment in that the liquid pressure sensor 23 is further provided in the liquid supply path 20 in addition to the system of the first embodiment. In addition to the temperature detection signal S _T from the liquid temperature sensor 21 and the flow rate detection signal S _Q from the liquid flow rate sensor 22, the control unit 30 of the second embodiment receives the pressure detection signal S _P from the liquid pressure sensor 23. type, in addition to the flow rate Q _L and temperature T _L of the liquid of the liquid, the flow rate of the gas that is required on the basis of the pressure P _L of the liquid in that they are calculable configured, differently from the first embodiment ing.

Next, operation | movement of the gas dissolution system 1b in this Embodiment 2 is demonstrated.
FIG. 5 shows the characteristics of how the concentration of the gas dissolved in the liquid changes with respect to the liquid pressure. In addition, since the pressure of both is balanced at the interface between the gas and the liquid, the pressure of the liquid may be regarded as the pressure of the gas.

As shown in FIG. 5, the solubility of the gas is proportional to the pressure. When the temperature is constant, the solubility of the gas increases as the pressure increases. In other words, the volume of the gas dissolved in a certain amount of gas is constant regardless of the pressure. This is called Henry's Law. Henry's law is the law that applies to many gases when the pressure is not too high and the temperature is not too low. More specifically, the solubility of a gas in a liquid is proportional to the partial pressure of that gas in contact with the liquid. When dissolution of a gas liquid is in an equilibrium state, Equation (4) is established from the law of conservation of mass.
C _A / C _LA = H (4)
(Where C _A : gas concentration (pressure), C _LA : gas concentration dissolved in liquid, H: constant)
Therefore, the temperature-saturated solubility characteristic described in the first embodiment changes according to the pressure of the liquid (gas) based on Henry's law.

FIG. 6 shows changes in temperature-saturated solubility characteristics with respect to changes in liquid pressure. As shown in FIG. 6, as the pressure of the liquid increases from p1 to p3 (p1 <p2 <p3), the saturation solubility q _p1 , q _p2 , q _p3 increases. If the saturation solubility at a predetermined temperature t at pressure p is expressed by q _p (t), the saturation solubility is q _p1 (T) <q _p2 (T) <q _p3 (T ) As described in the first embodiment, since the temperature-saturation solubility characteristic is uniquely determined if the pressure is constant, the temperature-saturation solubility characteristic should be measured and stored in advance within the range of the expected pressure change. For example, even when the pressure changes in addition to the temperature, the saturation solubility at the temperature and the pressure can be specified. Saturation solubility is expressed in terms of the unit volume of liquid or the weight of gas relative to unit weight, so if you know the saturation solubility and the flow rate of liquid, you can calculate the flow rate (volume) of gas required to dissolve with saturation solubility. It turns out that it is.

Therefore, in the second embodiment, the control unit 30 stores a plurality of temperature-saturated solubility characteristics measured in advance for a plurality of pressures. The control unit 30 determines the temperature-saturation solubility characteristic to be used based on the liquid pressure P _L indicated by the pressure detection signal S _P input from the temperature pressure sensor 23, and detects the temperature input from the liquid temperature sensor 21. based on the fluid temperature T _L indicated by the signal S _T, it identifies the saturation solubility D _TP in the liquid pressure P _L and the liquid temperature T _L. The liquid flow rate QL indicated by the flow rate detection signal S _Q inputted from the liquid flow sensor 22, based on the specified saturation solubility D _TP, and calculates the required gas flow Qreq, the required gas flow Qreq is supplied In this way, the mass flow controller 13 is operated. The detailed calculation after the temperature-saturated solubility characteristic corresponding to the measured pressure is selected is as described in the first embodiment.

  In addition, the temperature-saturation solubility characteristic for every pressure can be obtained by measuring the volume of the gas melt | dissolved per unit volume of the liquid used with the said gas dissolution system 1b, changing temperature. The temperature-saturation solubility characteristic measured according to pressure may be measured for a certain number of pressures. When there is no temperature-saturated solubility characteristic corresponding to the measured liquid pressure, an interpolation is performed using the temperature-saturated solubility characteristic measured for the liquid pressure approximating the measured liquid pressure before and after, Saturated solubility for the measured liquid pressure and liquid temperature can be obtained. Further, as described in the first embodiment, the saturation solubility may be obtained based on a predetermined relational expression.

  Next, a specific operation of the gas dissolution system 2 will be described with reference to a flowchart shown in FIG. The gas dissolution method 1b based on the flowchart is performed by the control unit 30 executing a predetermined gas dissolution program.

In step S201, the control unit 30 determines whether it is time to execute the gas dissolving method 2 of the second embodiment. If it is not the execution timing (NO), the process returns. If it is determined that the execution timing of the gas dissolution method 2 (YES), the process proceeds to step S202, the control unit 30, flows through the liquid supply passage 20 based on the detected flow rate signal S _Q inputted from the liquid flow sensor 22 The liquid flow rate Q _L to be measured is measured. Then the process proceeds to step S203, the control unit 30 refers to the temperature detection signal S _T inputted from the liquid temperature sensor 21 measures the nearest liquid temperature T _L. In step S204, the control unit 30 measures the liquid pressure P _L in the liquid channel 20 based on the pressure detection signal S _P input from the liquid pressure sensor 23.

Then the process proceeds to step S205, the control unit 30, a plurality of different temperatures are provided for each pressure - with reference to the saturation solubility characteristics, temperature corresponding to the measured fluid pressure P _L - selecting saturation solubility characteristics. Then, the process proceeds to step S205, where the control unit 30 specifies the saturated solubility _DTP of the gas at the measured liquid temperature T _L from the selected temperature-saturated solubility characteristic.

In addition, when the temperature-saturated solubility characteristic directly corresponding to the liquid pressure P _L does not exist, the control unit 30 has two temperature-saturated solubility characteristics approximate to the measured liquid pressure P _L (for example, , Refer to the characteristic that is closest to the measured liquid pressure P _L. Then, each temperature - saturation solubility properties (eg, q1 and q2) with reference to the saturation solubility of the gas in the measured fluid temperature T _L (e.g., saturation solubility D _T2 for saturation solubility D _T1, q2 for q1) Is identified. The saturated solubility D _TP is calculated based on, for example, the relational expression of the equation (5) by interpolating between the approximate saturated solubility D _T1 and D _T2 .
D _TP = w · D _T1 + (1−w) · D _T2 (5)

However, w is a weighting coefficient (0 <w <1), and is determined according to the degree of divergence between the measured liquid pressure PL and the pressure at the time of measurement of the saturated solubility characteristics q1 and q2. For example, if the measurement pressure of the saturation solubility characteristic q1 is P ₁ and the measurement pressure of the saturation solubility characteristic q2 is P ₂ , the weighting coefficient w can be calculated as in Expression (6).
w = | P _L −P ₂ | / | P ₁ −P ₂ | (6)

When the saturated solubility DT is calculated, the process proceeds to step S206, and the control unit 30 is for dissolving the gas in the liquid with the saturated solubility D _TP based on the liquid flow rate Q _L and the saturated solubility D _TP measured in step S202. A necessary gas flow rate (necessary gas flow rate Qreq) is calculated.

Shifts required gas flow Qreq steps S207 Once calculated, the control unit 30, the flow rate of the gas supplied to the dissolution unit 15 outputs a flow command signal C _Q for required gas flow Qreq the mass flow controller 13. The mass flow controller 13, based on this flow command signal C _Q and adjust the flow rate of the gas, the gas which has been adjusted to the required gas flow Qreq is supplied to the melting zone 15. In the dissolving part 15, this gas is dispersed in the liquid as fine bubbles. At this time, the gas flow rate is adjusted to a necessary gas flow rate Qreq necessary and sufficient to dissolve the gas in the liquid with the saturation solubility, so that the gas can be dissolved in the liquid without excess or deficiency.

  As described above, according to the gas dissolution system of the second embodiment, in addition to the advantages of the first embodiment, the temperature-saturated solubility characteristics measured in advance in consideration of the liquid pressure in addition to the liquid temperature are referred to. Therefore, even in a system in which the pressure fluctuates, there is an advantage that the required gas flow rate can be accurately calculated and supplied.

(Embodiment 3)
Embodiment 3 of the present invention relates to an invention configured to be able to set the solubility of a desired gas. Below, although the modified example of the structure which enabled arbitrary gas solubility to the gas dissolution system of the said Embodiment 1 is demonstrated, the same deformation | transformation is also possible with respect to the gas dissolution system of the said Embodiment 2. FIG. The same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted as appropriate.

FIG. 8 shows a system configuration diagram of a gas dissolution system in the third embodiment.
As shown in FIG. 8, the gas dissolution system 1c in the third embodiment has substantially the same configuration as that in the first embodiment. However, the first embodiment is different from the first embodiment in that an operation unit 31 for inputting information by an operator is connected to the control unit 30. In addition, when the desired gas solubility is set from the operation unit 31, the control unit 30 according to the third embodiment can calculate the gas flow rate necessary for dissolving the gas in the liquid with the desired gas solubility. Also in the point which is comprised, it differs from the said Embodiment 1.

  Next, a specific operation of the gas dissolution system 1c will be described with reference to the flowchart shown in FIG. The gas dissolution method 3 based on the flowchart is performed by the control unit 30 executing a predetermined gas dissolution program.

In step S301, the control unit 30 determines whether it is time to execute the gas dissolving method 3 of the third embodiment. If it is not the execution timing (NO), the process returns. If it is determined that the execution timing of the gas dissolution method 3 (YES), the process proceeds to step S302, the control unit 30, flows through the liquid supply passage 20 based on the detected flow rate signal S _Q inputted from the liquid flow sensor 22 The liquid flow rate Q _L to be measured is measured. Then the process proceeds to step S303, the control unit 30 refers to the temperature detection signal S _T inputted from the liquid temperature sensor 21 measures the nearest liquid temperature T _L.

Next, in step S304, when there is an input from the operation unit 31, the control unit 30 inputs a desired gas solubility Ddes instructed by the operator based on the input information. Then the process proceeds to step S305, the control unit 30, a temperature - with reference to the saturation solubility characteristics, to identify the saturation solubility D _T of the gas in the measured fluid temperature T _L. Next, the process proceeds to step S306, where the control unit 30 compares the saturated solubility _DT of the gas with the desired gas solubility Ddes. If desired gas solubility DDES who instructed the operator must be at or below the saturation solubility D _T at that temperature, it can be dissolved gas in the liquid at a desired gas solubility DDES, gas in solubility exceeding saturation solubility D _T It is impossible to dissolve.

So if the desired gas solubility Ddes is determined to be less than the saturation solubility D _T in step S307 (YES), the process proceeds to step S308, the control unit 30, dissolved gas in the liquid at the desired gas solubility Ddes The necessary gas flow rate Qreq suitable for the calculation is calculated. On the other hand, if desired gas solubility Ddes is a value that exceeds the saturated solubility D _T (NO), the process proceeds to step S308, the control unit 30, must be suitable for dissolving the gas in the liquid at the saturated solubility D _T The gas flow rate Qreq is calculated. Then, the process proceeds to step S310, and the control unit 30 notifies the operator that the saturation solubility is set instead of the desired saturation solubility.

Incidentally, necessary gas flow for the desired gas solubility Ddes is necessary gas based on the gas weight is calculated by substituting the desired gas solubility Ddes instead saturation solubility D _T in the formula (1) of the first embodiment The flow rate Qreq may be calculated.

Shifts required gas flow Qreq steps S311 Once calculated, the control unit 30, a flow command signal C _Q for the flow rate of the gas supplied is required gas flow Qreq the dissolution section 15 outputs to the mass flow controller 13, A gas adjusted to the required gas flow rate Qreq is supplied to the dissolution unit 15.

As described above, according to the gas dissolution system of the third embodiment, the same advantages as those of the first embodiment (the advantages of the second embodiment when the operation unit 31 is provided in the gas dissolution system of the second embodiment). In addition, since the solubility of the desired gas can be set, it can be used when the solubility of the gas must be strictly controlled.
Further, according to the third embodiment, when it is determined that the solubility of the set gas exceeds the saturation solubility, the fact is notified, so that the operator can dissolve the gas with the solubility set by himself / herself. Recognize that this is not done and take appropriate measures.

(Other variations)
The present invention is not limited to the above-described embodiment, and can be appropriately modified and applied without departing from the spirit of the present invention.

  For example, in the said embodiment, although demonstrated on the assumption that the liquid dissolved in gas was one type, it is not limited to this, You may use multiple types of gas. Specifically, a plurality of gas supply paths including a gas tank, a mass flow controller, and necessary valves are provided in parallel for each type of gas, and the gas supply paths are connected to each other on the downstream side of each mass flow controller. The calculation of the required gas flow rate for each gas and the setting of the required gas flow rate for the mass flow controller may be executed by a gas supply system provided for each gas. According to Henry's law, the solubility of gases that can be dissolved in a given liquid is proportional to the partial pressure of each gas. Therefore, it is possible to set a gas flow rate that is necessary and sufficient for achieving saturation solubility or desired solubility for each gas.

  In the above embodiment, the data table is used to obtain the saturation solubility. However, as long as the computer can grasp the saturation solubility for a predetermined temperature and pressure, the saturation solubility may be obtained with other configurations. .

  Further, the saturation solubility is intermediate information and not necessarily information that the system must output. For this reason, the required gas flow rate may be obtained directly from the measured liquid temperature or liquid pressure.

  Furthermore, in the above-described embodiment, the temperature and pressure of the liquid are measured. However, the temperature of the gas and the pressure of the gas can be used as a substitute for the temperature of the liquid and the pressure of the liquid. It is also possible to use the temperature of the section or the liquid supply path.

  The gas dissolution system, the gas dissolution method, and the gas dissolution program of the present invention can be applied to an industrial plant or the like for use in dissolving a maximum amount or a desired amount of gas in a liquid.

Claims (9)

A gas dissolution system for dissolving a gas into a liquid,
A liquid supply path for supplying the liquid;
A gas supply path for supplying the gas;
A dissolving part for dissolving the gas in the liquid;
A flow rate measuring unit for measuring the flow rate of the liquid on the upstream side of the dissolving unit;
A temperature measuring unit for measuring the temperature of the liquid on the upstream side of the dissolving unit;
A calculation unit that calculates a necessary gas flow rate for dissolving the gas in the liquid based on the measured flow rate of the liquid and a saturation solubility characteristic of the gas with respect to the measured temperature of the liquid;
A gas flow rate control unit provided in the gas supply path on the upstream side of the dissolution unit, which controls the flow rate of the gas so that the gas is supplied at the required gas flow rate;
A gas dissolution system comprising: The dissolving part is
With a sintered metal filter,
The gas is dispersed in the liquid by the sintered metal filter to dissolve the gas in the liquid.
The gas dissolution system according to claim 1. A pressure measuring unit for measuring the pressure of the liquid on the upstream side of the dissolving unit;
The computing unit is
Calculating the required gas flow rate based on the measured flow rate of the liquid and the saturated solubility characteristics of the gas with respect to the measured pressure of the liquid and the measured temperature of the liquid;
The gas dissolution system according to claim 1 or 2. The calculation unit is configured to arbitrarily set the solubility of the gas in the liquid,
When the calculation unit determines that the set solubility of the gas is equal to or less than the saturation solubility of the gas, the calculation unit is required to dissolve the gas in the liquid with the solubility of the gas as the required gas flow rate. Calculating the flow rate of the gas,
The gas dissolution system according to any one of claims 1 to 3. When the calculation unit determines that the set solubility of the gas exceeds the saturation solubility of the gas, the calculation unit is required to dissolve the gas in the liquid with the saturation solubility of the gas as the required gas flow rate. Calculating the flow rate of the gas,
The gas dissolution system according to claim 4. A gas dissolving method for dissolving a gas in a liquid,
Measuring the flow rate of the liquid;
Measuring the temperature of the liquid;
Calculating a required gas flow rate for dissolving the gas in the liquid based on the measured flow rate of the liquid and a saturation solubility characteristic of the gas with respect to the measured temperature of the liquid;
Controlling the flow rate of the gas so that the gas is supplied at the required gas flow rate;
Dissolving the gas supplied at the required gas flow rate in the liquid;
A gas dissolving method comprising: Measuring the pressure of the liquid,
In the step of calculating the required gas flow rate, the required gas flow rate is based on the measured flow rate of the liquid and the saturation solubility characteristic of the gas with respect to the measured pressure of the liquid and the measured temperature of the liquid. ,
The gas dissolution method according to claim 6. A gas dissolution program for dissolving a gas in a liquid,
On the computer,
A function of inputting the flow rate of the liquid;
A function of inputting the temperature of the liquid;
A function of calculating a required gas flow rate for dissolving the gas in the liquid based on the input flow rate of the liquid and a saturation solubility characteristic of the gas with respect to the input temperature of the liquid;
A function of controlling the flow rate of the gas so that the gas is supplied at the required gas flow rate;
Gas dissolution program for running A gas dissolution program for dissolving a gas in a liquid,
On the computer,
A function of inputting the flow rate of the liquid;
A function of inputting the temperature of the liquid;
A function of inputting the pressure of the liquid;
The required gas flow rate for dissolving the gas in the liquid based on the input flow rate of the liquid and the saturated solubility characteristics of the gas with respect to the input pressure of the liquid and the input temperature of the liquid. A function to calculate,
A function of controlling the flow rate of the gas so that the gas is supplied at the required gas flow rate;
Gas dissolution program for running

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