JP4323631B2 - Dissolved oxygen reduction device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a device for reducing dissolved oxygen, and in particular, various liquids, for example, water for food processing, alcoholic beverages such as sake and wine, soft drinks such as juice, seasonings such as soy sauce, liquid foods such as edible oil, The present invention relates to an apparatus for reducing dissolved oxygen contained in liquid chemicals such as photographic developers and liquid cosmetics.
[0002]
[Prior art and problems to be solved by the invention]
In order to prevent the components from being oxidized by the dissolved oxygen in the liquid and the growth of bacteria, the dissolved oxygen in the liquid is removed (reduced). As a method for reducing dissolved oxygen in various liquids, a gas degassing method for bubbling an inert gas in the liquid, a heat degassing method for heating the liquid, or a deoxygenating agent such as sulfite or vitamin C in the liquid. A chemical deaeration method for injection, a vacuum deaeration method for reducing the pressure in a container storing liquid, a membrane deaeration method using a deoxygenation film, and the like are known.
[0003]
Among these methods, the gas degassing method is difficult to achieve sufficient oxygen removal by simple bubbling of inert gas. For example, in order to improve the removal efficiency of dissolved oxygen, a plurality of bubbling tanks are used. They are arranged in series (JP-A-6-296959), or a liquid containing fine nitrogen gas bubbles is allowed to flow at an ultra-high speed to create a vigorous stirring state (JP-A-5-184811, JP-A-1-297105). Various proposals such as a combination of vacuum degassing and gas degassing (Japanese Patent Laid-Open No. 62-294482) have been made. In addition, methods for generating fine bubbles in a liquid during a deaeration operation have been proposed (Japanese Patent Laid-Open Nos. 6-63371, 6-205813, etc.).
[0004]
However, in these conventional methods, it cannot be said that the degassing efficiency of dissolved oxygen is sufficiently high, and improvement of the degassing efficiency, downsizing of the apparatus, and cost reduction are required.
[0005]
Accordingly, an object of the present invention is to provide a dissolved oxygen reducing device that can efficiently reduce dissolved oxygen with a simple device configuration, and can reduce the size and cost of the device.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, a dissolved oxygen reducing device of the present invention includes an inert gas introduction unit that introduces an inert gas into a liquid that is fed to a storage tank by a liquid feed pump, and an inert gas introduction unit. A gas-liquid mixing unit in which a gas-liquid mixing filler is filled in the downstream pipe; and an oxygen component that is provided on the downstream side of the gas-liquid mixing unit and on the upstream side of the storage tank and that is diffused from the liquid a gas separator for separating discharging inert gas, the dissipation of oxygen-containing gas discharged in the gas separator, said liquid from said liquid feed pump is fed to the path leading to said inert gas inlet part And a gas circulation path for re-introduction .
[0007]
Further, the dissolved oxygen reducing apparatus of the present invention is that the length of the gas-liquid mixing portion is 150mm or more, and wherein the inner diameter of said gas-liquid mixing portion is 23mm or more. Further, the inert gas introduction part is provided at a central part of the liquid supply pipe, and includes a sparger that ejects the inert gas radially from the central part of the pipe, and the inert gas of the sparger is characterized in that The gas ejection part is formed of a sintered metal.
[0008]
In addition, the pre-Symbol storage tank is characterized in that it comprises an inert gas substitution means for substituting an inert gas atmosphere.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Figure 1 is a system diagram showing a reference example of Dissolved oxygen reducing apparatus. The dissolved oxygen reducing device 10 is provided between the storage tank 1 on the delivery side and the storage tank 2 on the reception side, and flows through the liquid feed pump 11 and the downstream pipe of the liquid feed pump 11. An inert gas introduction part 12 for introducing an inert gas into the liquid, and a gas-liquid mixing part 14 in which a gas-liquid mixing filler 13 is filled in a downstream pipe of the inert gas introduction part 12 are provided. In addition, the storage tank 2 on the liquid receiving side also serves as a gas separation unit.
[0010]
The storage tank 2 on the liquid receiving side is provided with an exhaust path 3 for separating and discharging an inert gas containing oxygen diffused from the liquid, and introduces a purge gas for purging the oxygen in the tank. A purge gas introduction path 4 is provided. Both the passages 3 and 4 are provided with pressure regulating valves (holding valves) 5 and 6 for keeping the pressure in the tank in a predetermined range, respectively. A dissolved oxygen concentration meter 7 for measuring the amount of dissolved oxygen is provided.
[0011]
In the inert gas introduction part 12, for example, an inert gas supply source 15 for supplying an inert gas such as nitrogen gas, a pressure reducing valve 16 for setting the supply pressure of the inert gas to a predetermined pressure, An inert gas supply path 19 including a flow meter 17 and a control valve 18 for setting the flow rate of the inert gas to a predetermined flow rate is connected, and a liquid feed is provided at the tip of the inert gas supply path 19. A sparger 20 that ejects an inert gas radially from the center of the pipe is provided.
[0012]
For example, as shown in FIG. 2, the sparger 20 is provided with a large number of jet ports 22 formed of fine through holes on the peripheral surface of the cylindrical body 21, or as shown in FIG. What was formed with the shaped sintered metal 23 can be used. By forming fine bubbles with such a sparger 20 and ejecting them radially into the liquid flowing in the pipe, the gas-liquid contact mixing can be promoted, and the liquid and the inert gas are efficiently mixed. can do. Depending on the liquid flow rate and the degree of removal of dissolved oxygen, it may be sufficient to connect an inert gas supply path to the liquid supply pipe.
[0013]
As the filler 13 of the gas-liquid mixing unit 14, a material having a function of promoting gas-liquid mixing such as a metal scourer, a ring, a metal piece such as a coil, a plastic or metal Raschig ring can be used. . Such a filler 13 is preferably detachably inserted into the liquid feeding pipe in a state of being housed in a liquid permeable container, for example, a container formed of a punching plate or a wire mesh. Thereby, filling and taking out of the filling material 13 into the pipe can be easily performed, and the replacement of the filling material 13 is easy. The washing of the filling material 13 can be performed by washing the container with an ultrasonic washing machine or the like. Can also be done easily.
[0014]
Moreover, although the discharge pressure of the liquid feed pump 11 varies depending on the structure and arrangement of the storage tank 2 on the receiving side and the resistance of the filling 13, about 0.2 MPa is usually sufficient, and the supply of inert gas A pressure of about 0.3 MPa that can be ejected into the liquid is sufficient. Therefore, it is possible to use a liquid pump having a low price and a general lift. In addition, normal accessory equipment such as a pressure gauge 24 and a bypass valve 25 can be provided in the liquid feed pump 11 portion.
[0015]
The liquid containing dissolved oxygen extracted from the delivery-side storage tank 1 is fed by the liquid feed pump 11 toward the reception-side storage tank 2, and is discharged from the sparger 20 by the inert gas introduction unit 12. After the active gas is introduced, it flows into the gas-liquid mixing unit 14 in a gas-liquid mixed state, gas-liquid mixing is promoted by the filler 13, and dissolved oxygen in the liquid is diffused into the inert gas, so that the receiving side It flows into the storage tank 2.
[0016]
The introduction amount of the inert gas in the inert gas introduction unit 12 varies depending on the type of liquid, the flow rate, the dissolved oxygen amount, and the desired dissolved oxygen removal amount. In general, if the inert gas amount is increased, that is, gas-liquid The amount of dissolved oxygen removed can be increased by increasing the gas-liquid ratio in the mixed flow. Then, gas-liquid mixing is promoted by the filler 13 in the gas-liquid mixing unit 14 and the bubbles of the inert gas are further refined, so that dissolved oxygen can be more effectively diffused from the liquid.
[0017]
In the gas-liquid mixing unit 14, the amount and amount of dissolved oxygen removed can be adjusted by appropriately selecting the type and shape of the filling 13 and appropriately setting the length and the inner diameter. The length and inner diameter of the gas-liquid mixing unit 14 vary depending on the type of liquid, flow rate, dissolved oxygen amount, inert gas introduction amount, desired dissolved oxygen removal amount, and there is a mutual relationship between the length and the inner diameter. The length of the gas-liquid mixing part 14 is preferably 150 mm or more, usually 300 to 600 mm, and the inner diameter is preferably 23 mm or more, usually 40 mm or more. If the length is too short or the inner diameter is too small, mixing of gas and liquid may not be promoted sufficiently. Moreover, even if it lengthens unnecessarily, the amount of dissolved oxygen removal does not improve so much. On the other hand, if the inner diameter is increased, the flow velocity is lowered and the effect of gas-liquid mixing is lost, so the maximum diameter is determined by the flow rate. In general, if the gas-liquid mixing unit 14 is made too long or the inner diameter is made too large, not only will the cost be increased, but also the handling of the filler 13 will be difficult. 11 will be increased in size.
[0018]
When passing through the gas-liquid mixing unit 14, bubbles mixed with the liquid, that is, the inert gas containing oxygen released from the liquid is gradually gas-liquid separated in the pipe due to the difference in specific gravity, and the storage tank Gas-liquid separation is performed almost completely in the interior of the storage tank 2 and exhausted from the exhaust path 3 provided in the upper part of the storage tank 2. At this time, by providing the dissolved oxygen concentration meter 26 on the downstream side of the gas-liquid mixing unit 14, the effect of removing dissolved oxygen can be continuously confirmed.
[0019]
In addition, it is desirable that the storage tank 2 that receives the liquid from which dissolved oxygen has been removed be purged with an inert gas in advance. This purge operation is performed before the operation of the dissolved oxygen reduction device 10 by passing a purge gas made of an inert gas such as nitrogen gas set to a predetermined pressure by the pressure reducing valve 8 of the purge gas introduction path 4 through the pressure control valve 6 into the tank. The oxygen concentration in the tank is equal to or less than the dissolved oxygen amount of the liquid after the dissolved oxygen removal process. It is desirable to carry out until. As described above, the inert gas replacement means including the purge gas introduction path 4 and the exhaust path 3 is provided to replace the inside of the tank with an inert gas atmosphere in advance, so that the treatment is performed by oxygen contained in the air in the tank. It is possible to prevent the dissolved oxygen concentration of the later liquid from increasing.
[0020]
When the dissolved oxygen reducing device 10 is operated and liquid and oxygen-containing inert gas flows into the storage tank 2 and the pressure in the tank exceeds the set pressure of the pressure regulating valve 5, the pressure regulating valve 5 is opened and the inside of the tank is opened. Are exhausted from the exhaust path 3. During liquid storage, a small amount of purge gas is continuously introduced from the pressure control valve 6 as a seal gas, and the inside of the tank is maintained at a pressure slightly higher than atmospheric pressure. Further, when the inside of the tank falls below the set pressure of the pressure control valve 6 due to the consumption of the liquid in the storage tank 2, the pressure control valve 6 is opened by a predetermined amount and the purge gas in the purge gas introduction path 4 is replenished into the tank.
[0021]
Thus, the pressure in the storage tank 2 is maintained within a predetermined range by the pressure control valves 5 and 6. The set pressure of the storage tank 2 is in a range in which the air can be prevented from entering the tank, and may be equal to or lower than the normal pressure of the storage tank 2, for example, about 500 mmAq is appropriate.
[0022]
As described above, the inert gas is introduced into the liquid fed by the liquid feed pump 11 and then introduced into the gas-liquid mixing unit 14 to further refine the bubbles of the inert gas to promote the gas-liquid mixing. Thus, the dissolved oxygen concentration in the liquid can be removed to 1 mg / L (ppm) or less, and further to about 0.2 mg / L (ppm), and the gas-liquid mixing unit 14 and the inert gas introduction amount, etc. By appropriately setting the conditions, the amount of dissolved oxygen in the liquid after the treatment can be adjusted to a desired amount. In addition, even if the bubble size of the introduced inert gas is large, sufficient dissolved oxygen removal effect is obtained, and it is not heated to a high temperature or an additive harmful to the human body such as an oxygen scavenger is used. It can be carried out with a simple apparatus configuration, and there is no food hygiene problem in the treatment of liquid food, and there is no influence on the human body.
[0023]
FIG. 4 is a system diagram showing an embodiment of the dissolved oxygen reduction device of the present invention, and shows an example in which a gas-liquid separator 31 as a gas separation unit is provided on the downstream side of the gas-liquid mixing unit 14. is there. Thus, by providing the gas-liquid separator 31, the inert gas that has taken in the oxygen diffused from the liquid is quickly separated by the gas-liquid separator 31 and exhausted from the exhaust gas path 32. The amount of gas flowing into the storage tank 2, that is, the amount of oxygen can be greatly reduced. Thereby, since the raise of the oxygen concentration in the gaseous phase of the storage tank 2 decreases, the amount of inert gas introduced from the purge gas introduction path 4 can be reduced.
[0024]
Various types of gas-liquid separators 31 can be used. For example, a centrifugal gas-liquid separator can be used. Since other apparatus configurations can be formed in the same manner as the reference example shown in FIG. 1, the same components as those in the reference example are denoted by the same reference numerals, and detailed description thereof is omitted.
[0025]
Further, the inert gas (separated gas) separated from the liquid by the gas-liquid separator 31 contains oxygen removed from the liquid, and the oxygen concentration is higher than the initial inert gas. Since the increase in oxygen concentration is slight, the separation gas is reused as an inert gas for removing dissolved oxygen introduced into the liquid according to the oxygen concentration and the amount of dissolved oxygen in the liquid. can do. That is, a gas circulation path 34 including a blower 33 for pumping the separated gas discharged to the exhaust gas path 32 to the downstream side of the liquid feed pump 11 and to the upstream side of the inert gas introduction unit 12 is provided. As a result, the utilization efficiency of the inert gas can be increased and the consumption thereof can be reduced.
[0026]
It is also possible to arrange a plurality of sets of dissolved oxygen reducing devices 10 as described above in parallel or in series, and the liquid in the storage tank 2 can be circulated upstream of the liquid feed pump 11 for reprocessing. It is.
[0027]
The inert gas may be selected according to the type of liquid and the inert gas supply environment, such as nitrogen gas, argon gas, carbon dioxide, or the like.
[0031]
【The invention's effect】
As described above, according to the present invention, dissolved oxygen can be efficiently removed with a simple apparatus configuration. Further, the apparatus cost and running cost can be reduced as compared with the conventional apparatus, and the apparatus can be downsized. In particular, since the liquid after processing is not adversely affected, foods and the like can be processed safely.
[Brief description of the drawings]
FIG. 1 is a system diagram showing a reference example of a dissolved oxygen reducing device.
FIG. 2 is a cross-sectional view showing an example of a sparger.
FIG. 3 is a cross-sectional view showing another example of a sparger.
It is a system diagram illustrating one embodiment of a dissolved oxygen reducing apparatus of the present invention; FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Sending side storage tank, 2 ... Receiving side storage tank, 3 ... Exhaust path, 4 ... Purge gas introduction path, 5, 6 ... Pressure control valve, 7 ... Dissolved oxygen concentration meter, 10 ... Dissolved oxygen reducing device, 11 ... Liquid feed pump, 12 ... inert gas introduction part, 13 ... filling, 14 ... gas-liquid mixing part, 15 ... inert gas supply source, 16 ... pressure reducing valve, 17 ... flow meter, 18 ... control valve, 19 ... non-use Active gas supply path, 20 ... sparger, 21 ... cylindrical body, 22 ... spout, 23 ... sintered metal, 24 ... pressure gauge, 25 ... bypass valve, 26 ... dissolved oxygen concentration meter, 31 ... gas-liquid separator, 32 ... exhaust gas path, 33 ... blower, 34 ... gas circulation path

Claims (6)

An inert gas introduction part that introduces an inert gas into the liquid that is sent to the storage tank by the liquid delivery pump, and a gas that is filled with a gas-liquid mixing filler in the downstream pipe of the inert gas introduction part A liquid mixing unit, a gas separator provided on the downstream side of the gas-liquid mixing unit and on the upstream side of the storage tank, for separating and discharging an inert gas containing an oxygen component released from the liquid , and the gas separation A gas circulation path for reintroducing the diffused oxygen-containing gas discharged by the vessel into the liquid being fed through the path from the liquid feed pump to the inert gas introduction part. Dissolved oxygen reduction device.   The dissolved oxygen reduction device according to claim 1, wherein the gas-liquid mixing part has a length of 150 mm or more.   The dissolved oxygen reducing device according to claim 1, wherein the gas-liquid mixing part has an inner diameter of 23 mm or more.   2. The dissolved oxygen reduction according to claim 1, wherein the inert gas introduction portion includes a sparger that is provided at a central portion of the liquid feeding pipe and that radiates the inert gas radially from the central portion of the pipe. apparatus.   The dissolved oxygen reducing device according to claim 4, wherein the sparger has an inert gas ejection portion formed of sintered metal.   2. The dissolved oxygen reducing device according to claim 1, wherein the storage tank includes an inert gas replacement means for replacing the inside of the tank with an inert gas atmosphere.

Images