JP3574576B2 - Degassing device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a liquid deaerator.
[0002]
[Prior art]
Dissolved gas in the liquid causes corrosion progress of the tube, generation of bubbles, reduction of heat exchange rate, etc., so it is necessary to degas depending on the purpose of use of the liquid, and as one of the degassing devices, As shown in FIG. 5, a gas permeable tube 2 'is accommodated in a decompression chamber-1' having a degassed liquid inlet 111 'and an outlet 112', and both ends of the tube 2 'are closed. The liquid containing the dissolved gas is connected to the gas-permeable tube 2 'while the pressure in the chamber-1' is reduced by the vacuum pump from the vacuum port 32 'in the upper part of the chamber. A method of distributing is known.
[0003]
[Problems to be solved by the invention]
When a liquid leaks in the chamber of the deaerator, the leaked liquid is eventually sucked into the evacuation pump. The operation of the deaerator is stopped by detecting the sucked liquid.
However, since the amount of leaked liquid is usually very small and the leak rate is low, a certain time (T) elapses until the level of the leaked liquid in the chamber reaches a level that can be sucked by the vacuum pump. The gas permeable tube 2 'is immersed in the leaking liquid as shown by L' in FIG. In FIG. 5, L ₀ ′ virtually indicates a liquid level at which the leaking liquid can be sucked by the vacuum pump.
As shown by the liquid level L 'in FIG. 5, when most of the gas permeable tube 2' is immersed in the leaking liquid, the effective area of the gas permeable tube is reduced. The degassing flow amount of the degassed liquid is reduced accordingly, and degassing during the time T until the degassing device is stopped causes poor degassing, and it is difficult to guarantee a predetermined low dissolved gas amount due to degassing.
[0004]
Further, when the main component of the liquid to be degassed is a solvent and contains a solid as a solute, for example, when the liquid to be degassed is an ink liquid, the conventional deaerator has one suction port, and this suction port Is liable to be clogged with solids dried and solidified due to rapid evaporation of the solvent under reduced pressure, making it difficult for liquid leaking from the chamber to be transferred to the vacuum pump, making it impossible to accurately detect liquid leakage. In some cases, the operation of the deaerator cannot be stopped in a timely manner.
[0005]
An object of the present invention is to perform a degassing process using a gas permeable tube, and even if a small amount of liquid leaks, the degassing efficiency can be maintained well and the operation can be accurately stopped by reliable liquid leak detection. An object of the present invention is to provide a deaerator.
[0006]
[Means for Solving the Problems]
The degassing apparatus according to claim 1 accommodates a gas permeable tube in a decompression chamber, provides an inlet and an outlet for the liquid to be degassed into the gas permeable tube in the chamber, and has a plurality of suction holes at the tip. characterized in that attaching the evacuation pipe before Symbol chamber.
The degassing device according to claim 2, wherein a gas permeable tube is housed in a decompression chamber, and an inlet and an outlet for the liquid to be degassed to the gas permeable tube are provided in the chamber, and the tip portion is formed into a manifold. A vacuum evacuation tube having a plurality of suction holes is attached to the chamber such that a tip portion thereof is close to a bottom surface in the chamber.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an example of the deaerator according to the present invention.
In FIG. 1, reference numeral 1 denotes a vacuum chamber having an inlet 111 and an outlet 112 for a liquid to be degassed. Numeral 2 denotes a gas-permeable tube, which is housed in a loop in the chamber-1 multiple times and has both ends connected to an inlet 111 and an outlet 112 of the liquid to be degassed. Numeral 3 is a vacuum evacuation tube provided with a plurality of suction holes 31,... (The opening of the tip also belongs to the suction hole) at the tip, and is introduced into the chamber-1 from the upper side wall of the chamber to bring the tip 30 into the chamber. It is located on the inner bottom 12.
[0008]
In order to deaerate the liquid using the deaerator according to the present invention, a vacuum pump is connected to the outlet 32 of the vacuum tube 3 and gas permeation is performed while maintaining the inside of the chamber 1 at a predetermined reduced pressure. The liquid is passed through the sex tube 2.
[0009]
During this deaeration process, if a liquid leaks into the chamber 1 and the tip 30 of the vacuum tube 3 is closed by the leaked liquid level, the inside of the vacuum tube 3 is shut off from the inside of the chamber. As a result, the degree of pressure reduction in the evacuation tube 3 rapidly increases, and the leaked liquid is sucked into the evacuation pump. Therefore, if the tip of gas-permeable tube 3 (the portion provided with the suction hole) is disposed below the lowermost surface 20 of gas-permeable tube 2 with multiple loops, Before the surface of the leaked liquid comes into contact with the gas permeable tube 2, the leaked liquid can be sucked into the vacuum pump, thereby preventing the gas permeable tube 2 from being immersed in the leaked liquid. Further, since the leaked liquid is sucked into the vacuum pump instantaneously, the inside of the chamber 1 is substantially maintained at the predetermined degree of reduced pressure. Therefore, degassing with sufficient degassing efficiency can be guaranteed despite liquid leakage.
[0010]
If the amount of the leaked liquid sucked into the evacuation pump becomes a certain amount and a liquid leak is detected, the deaeration operation is stopped, but until this stop, degassing with sufficient deaeration efficiency is performed. Because it is guaranteed, even if there is a slight delay in operation stoppage, there will be no problem.
[0011]
In the above description, when the liquid to be degassed is a liquid containing a solvent as a main component such as an ink liquid, particularly when the solvent is a low molecular organic solvent such as ethanol, the solvent in the leaked liquid is rapidly reduced under reduced pressure. Although the suction holes are liable to be clogged with dry solids due to undesired vaporization, the deaerator according to the present invention has a plurality of suction holes in the evacuation tube, so that all the suction holes are blocked compared to a single case. , The liquid leakage in the chamber can be guided to the evacuation pump well, and the deaerator can be stopped accurately by detecting the liquid leakage.
[0012]
In the above description, as shown in FIG. 2, the evacuation tube 3 may be a manifold having a distal end in a manifold shape, and the end opening 31 of each branch tube may be used as a suction port.
[0013]
In the above, the plurality of suction holes or suction ports of the evacuation tube are usually located between the lower end of the multi-loop gas permeable tube and the inner bottom surface of the chamber.
[0014]
To reduce the size of the deaerator by reducing the distance between the lower end of the gas permeable tube and the inner bottom surface of the chamber, as shown in FIG. It can be bent over and positioned between the lower end 20 of the gas permeable tube and the inner bottom surface 12 of the chamber.
[0015]
In the above, if the level of the leaking liquid in the chamber is a height (h) at which about 10% of the membrane area of the gas-permeable tube is immersed, 90% of the membrane area of the gas-permeable tube is reduced. Since the gas can be degassed with sufficient degassing efficiency, a plurality of suction holes or suction holes of the vacuum evacuation tube are positioned between the height h and the lower surface of the loop-shaped gas-permeable tube. You may let it.
[0016]
Examples of the gas permeable tube 2 include a polytetrafluoroethylene tube, a tetrafluoroethylene-perfluoroalkylvinylether copolymer tube, and an ethylene-tetrafluoroethylene copolymer tube. , A fluororesin tube such as polychlorotrifluoroethylene tube, a polyethylene tube, or a polypropylene tube can be used, and a large number of hollow fiber bodies are bundled in order to increase the membrane area per unit volume. Preferably, the diameter of the hollow fiber body is several hundred μm to several mm in inner diameter, and the number of bundles is several tens to several hundreds.
[0017]
For example, metal (particularly, stainless steel), glass, plastic, or the like can be used for the decompression chamber-1. Examples of the plastic include polytetrafluoroethylene and tetrafluoroethylene-perfluoroalkylvinyl ether copolymer. Examples thereof include a fluororesin, polypropylene, and polyethylene.
[0018]
To connect the liquid inlet (and outlet) of the decompression chamber to the gas-permeable tube, for example, as shown in FIG. 4, an inlet fitting 111 (outlet fitting 112) is provided at the end of the tube 2. A method can be used in which the wedge 113 and the cap nut 114 are used for connection, and the metal fitting is connected to the upper wall of the decompression chamber with the packing 115 and the nut 116. However, this configuration is merely an example, and an appropriate configuration can be adopted as long as the degassed liquid inlet and outlet for the parallel gas permeable tube can be provided at the upper part of the decompression chamber.
[0019]
As the evacuation tube 3, any material having corrosion resistance to the leaking liquid can be used. For example, a polytetrafluoroethylene tube or a tetrafluoroethylene-perfluoroalkylvinyl ether copolymer may be used. A coalesced tube, an ethylene-tetrafluoroethylene copolymer tube, a polychlorotrifluoroethylene tube, a polypropylene tube, a polyethylene tube and the like can be used.
[0020]
【Example】
(Comparative example)
A gas permeable tube formed by bundling 130 polytetrafluoroethylene tubes having an inner diameter of 1.0 mm, a thickness of 0.13 mm, and a length of 3.5 m and formed into a loop multiple times is provided with a suction port at the top. Was housed in a decompression chamber.
When a small amount of liquid leakage was created, the vacuum pump was driven so that the pressure in the chamber was reduced to -720 mmHg, and degassing was attempted by flowing a gas to be degassed with a dissolved oxygen amount of about 8 ppm at 100 ml / min. It became impossible to degas in a short time.
[0021]
〔Example〕
A stainless steel tube with a diameter of 10 mm, which is formed by drilling six suction holes with a diameter of 3 mm at the end and cutting the end at 45 °, is used as a vacuum evacuation tube 3, and the end is brought into contact with the bottom surface in the chamber, and all the suction holes are removed. It was the same as the comparative example except that it was arranged below the lowermost surface of the loop-shaped gas-permeable tube.
In the same manner as in the comparative example, a minute liquid leakage point was created, and the vacuum pump was driven so that the pressure inside the chamber was reduced to -720 mmHg, and the gas to be degassed having a dissolved oxygen amount of about 8 ppm was flowed at 100 ml / min. When the gas was tried, a considerably longer time elapsed than in the comparative example until the gas could not be degassed, and the dissolved oxygen amount of the liquid at the liquid outlet was about 3.2 ppm at the liquid outlet several minutes after driving. I was able to.
[0022]
【The invention's effect】
In the degassing apparatus according to the present invention, a sufficiently high degassing is performed even when a leak occurs in the chamber and the leak is detected by drawing the leaked liquid into a vacuum pump and the deaeration operation is stopped. Since degassing with gas efficiency can be guaranteed, even if there is a slight time delay in stopping the operation, operation is easy, and it is only necessary to pull in the evacuation tube until it reaches the inner bottom of the chamber. In addition, there is no need to mount a liquid leak sensor, and maintenance is simple and cost-effective.
[0023]
In addition, since the vacuum tube has a plurality of suction holes, even if the liquid to be degassed is a solution containing a solvent as a main component and the leaked liquid is solidified due to reduced pressure, the vacuum tube is not used. Good ventilation can be maintained, and the above advantages can be achieved.
[Brief description of the drawings]
FIG. 1 is a drawing showing an example of a deaerator according to the present invention.
FIG. 2 is a drawing showing another example of the distal end of the evacuation tube used in the deaerator according to the present invention.
FIG. 3 is a drawing showing a main part of another example of the deaerator according to the present invention.
FIG. 4 is a view showing an example of a connection structure between a gas permeable tube and an inlet or an outlet in a deaerator according to the present invention.
FIG. 5 is a view showing a conventional deaerator.
[Explanation of symbols]
1 Decompression chamber
111 Inlet 112 Outlet 2 Gas permeable tube 3 Vacuum tube 31 Suction hole or suction port

Claims (2)

Accommodating the gas permeable tubes in the vacuum chamber, provided with inlet and outlet of the degassing liquid to the gas permeable tubes to the chamber, the evacuation pipe having a plurality of suction holes at the tip before Symbol chamber A degassing device characterized by being attached. Accommodating the gas permeable tubes in the vacuum chamber, provided with inlet and outlet of the degassing liquid to the gas permeable tubes in the chamber, evacuated with both a plurality of suction holes when the distal end to the manifold shapes A deaerator wherein a pipe is attached to the chamber such that a tip end thereof is close to a bottom surface in the chamber.

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