JP2007145343A - Liquid storing tank - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid storing tank capable of effectively preventing bubbles from being entrapped and suitable in fields, including a manufacturing device for manufacturing polyurethane foamed resin, wherein serious influence is caused by bubbles. <P>SOLUTION: This liquid storing tank 10A has a discharging port 15A at its bottom surface, and is provided with a bubble mixing preventive device 21A comprised of a parasol part 22A covering over the discharging port 15A and a fixing means 25A for use in positioning the parasol part 22A at a specified height spaced apart from the discharging port 15A. Distance between the discharging port 15A and the parasol part 22A is set to 20 to 80 mm and at the same time the parasol part 22A is formed into a disk shape with a diameter of one to five times the diameter of the discharging port 15A. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a liquid storage tank including a bubble mixing prevention device.

  Conventionally, for example, when a polyurethane resin foam is manufactured, a liquid is stored in a liquid storage tank 50 as shown in FIG. 9, and the liquid is stored by a pump (not shown) connected to a discharge port 51 of the liquid storage tank 50. A liquid is supplied from the tank 50 to a foam injection machine (not shown), stirred by a stirring device of the foam injection machine, and discharged as a reaction mixture. In the production of a polyurethane resin foam, usually, two liquid storage tanks on the polyisocyanate component side and a liquid storage tank on the polyol component side are provided, and liquid is supplied from each liquid storage tank to the stirring device of the foam injection machine. Is transferred.

  However, when the amount of liquid in the tank decreases, the liquid is discharged from the discharge port 51 while forming a spiral, and bubbles are drawn into the liquid at that time. When bubbles are involved in the liquid, the amount of liquid transferred by the pump varies, making it difficult to stably transfer a certain amount. In particular, in the production of polyurethane resin foam, it is necessary to mix the liquid transferred from two tanks at a predetermined ratio by a stirrer, and if the liquid transfer amount changes and the mixing ratio changes, the polyurethane resin The foam cannot be obtained with a certain quality.

  In the field of nuclear power generation equipment, in the gas-liquid separation tank that separates vapor and gas, the vertical direction (in order to capture the mist (moisture) contained in the vapor by preventing the horizontal swirling flow of the liquid It has been proposed to provide a mist capturing means comprising a plate member in the vertical direction at the outlet. However, when this mist-capturing means is used in a liquid storage tank in a polyurethane resin foam production apparatus, pinholes are generated in the resulting polyurethane resin foam, and it is possible to constantly obtain a good quality one. It turned out to be difficult. This is intended to capture mist in the gas-liquid separation tank, so that a sufficient effect can be obtained if the entrainment of bubbles is moderately reduced, whereas in the production of polyurethane resin foams Since the polyurethane resin foam is formed by a chemical reaction, it is more susceptible to the influence of entrainment of bubbles, and it is assumed that the prevention of entrainment of bubbles is insufficient in the mist capturing means.

Japanese Patent Laid-Open No. 2003-240892

  The present invention has been made in view of the above points, and can effectively prevent entrainment of bubbles, and is particularly suitable in a field where influence of entrainment of bubbles is large, such as a polyurethane resin foam manufacturing apparatus. The purpose is to provide a liquid storage tank.

  According to the first aspect of the present invention, in the liquid storage tank having a discharge port on the bottom surface, air bubbles mixed comprising an umbrella portion covering the upper portion of the discharge port and a fixing means for positioning the umbrella portion at a certain height from the discharge port. A prevention device is provided.

  According to a second aspect of the present invention, in the first aspect, the distance between the discharge port and the umbrella portion is 20 to 80 mm.

  According to a third aspect of the present invention, in the first or second aspect, the umbrella portion has a disk shape having a diameter of 1 to 5 times the diameter of the discharge port.

  According to the present invention, even if the liquid in the tank is reduced, it is possible to effectively prevent bubbles from being caught in the liquid by the umbrella portion covering the upper portion of the discharge port. Moreover, the umbrella part can also prevent inhalation of dissolved air and bubbles contained in the raw material.

  Hereinafter, embodiments of the present invention will be described in detail. FIG. 1 is a longitudinal sectional view of a liquid storage tank according to a first embodiment of the present invention, FIG. 2 is a perspective view and a sectional view of a bubble mixing prevention device according to the first embodiment, and FIG. 3 is a liquid according to the second embodiment. FIG. 4 is a perspective view and a cross-sectional view of the bubble mixing prevention device according to the second embodiment, FIG. 5 is a vertical cross-sectional view of the liquid storage tank according to the third embodiment, and FIG. FIG. 7 is a longitudinal sectional view of a liquid storage tank according to the fourth embodiment, and FIG. 8 is a perspective view and a cross section of the bubble mixing prevention device according to the fourth embodiment. FIG.

  The liquid storage tank 10A of the first embodiment shown in FIG. 1 includes a tank body 11A and a bubble mixing prevention device 21A.

  The tank body 11A includes a cylindrical base body 13A having a bottom surface 12A and a lid portion 14A that covers the top of the base body 13A. A discharge port 15A is formed in the vertical direction substantially at the center of the bottom surface 12A. The discharge port 15A communicates with the inside and outside of the tank body 11A and protrudes in a cylindrical shape to the outside of the bottom surface 12A, and an opening / closing valve B is provided at a cylindrical portion outside the tank body 11A. The discharge port 15A is connected to a pump (not shown) via the open / close valve B, and further connected to a predetermined device (for example, a stirring device in a polyurethane resin foam manufacturing apparatus), and is connected to the tank main body 11A. The liquid can be transferred to a predetermined device. In addition, a liquid inlet 16A is formed in the lid portion 14A and connected to a liquid supply device (not shown). Note that the liquid inlet 16A is not required in a tank that opens the lid 14A and injects liquid.

  The bubble mixing prevention device 21A is provided in the tank body 11A above the discharge port 15A. The bubble mixing prevention device 21A is for preventing the gas from being caught in the liquid when the liquid stored in the tank body 11A is discharged from the discharge port 15A. As can be understood, an umbrella portion 22A covering the upper portion of the discharge port 15A, and fixing means for setting the umbrella portion 22A to a constant height h (shown in FIG. 1) from the discharge port 15A of the bottom surface 12A. 25A.

  The umbrella portion 22A has a size and a shape that can cover the discharge port 15A. In the present embodiment, the umbrella portion 22A is formed in a disc shape. It is particularly preferable that the umbrella portion 22A has a disk shape because the liquid hardly causes turbulent flow at the periphery of the umbrella portion 22A. Furthermore, it is preferable that the disc-shaped umbrella portion 22A has a diameter D that is 1 to 5 times the diameter (inner diameter) d of the discharge port 15A. If it is smaller than the above range, the upper part of the discharge port 15A cannot be reliably covered, and a vortex is formed above the discharge port 15A when the liquid is discharged, and the effect of preventing entrainment of bubbles is reduced. On the other hand, if it is larger than the above range, the umbrella portion 22A becomes too large, which is not only inconvenient in the design of the tank, but also increases the member cost.

  The fixing means 25A is configured to fix the umbrella portion 22A from the discharge port 15A of the bottom surface 12A to a constant height h, and has a structure in which the umbrella portion 22A is supported from below by a pillar member. The fixing means 25A of this embodiment is composed of an upright plate 26A as a column member that is provided upright so as to straddle the discharge port 15A, and the umbrella portion 22A is placed and fixed on the upper end of the upright plate 26A. ing. The upright plate 26A is formed radially from the center of the discharge port 15A so as not to prevent the liquid from being discharged from the discharge port 15A.

  The height of the umbrella portion 22A from the discharge port 15A of the bottom surface 12A (the distance to the upper end of the umbrella portion 22A) h is preferably 20 to 80 mm. When the height (distance) h is less than 20 mm, the gap between the discharge port 15A and the umbrella portion 22A is reduced, and the discharge of the liquid from the discharge port 15A is prevented. In particular, when the liquid stored in the liquid storage tank 10A has a relatively high viscosity, such as a polyisocyanate component used in the production of a polyurethane resin foam, it is between the discharge port 15A and the umbrella portion 22A. When the gap becomes small, the discharge becomes extremely hindered. On the other hand, when the height (distance) h exceeds 80 mm, the effect of covering the upper portion of the discharge port 15A with the umbrella portion 22A is reduced, and it is difficult to obtain the effect of preventing entrainment of bubbles. Furthermore, since the distance between the umbrella portion 22A and the bottom surface 12A becomes large, the fixing means 25A becomes large, and an excessive part is required, and a strength design that can withstand the pressure applied when the liquid is discharged is also required. The cost will increase.

  The liquid storage tank 10B of the second embodiment shown in FIG. 3 includes a tank body 11B and a bubble mixing prevention device 21B. The tank body 11B has the same configuration as the tank body 11A of the first embodiment. Reference numeral 12B denotes a bottom surface, 13B denotes a base body, 14B denotes a lid, 15B denotes a discharge port, and 16B denotes a liquid injection port.

  In the bubble mixing prevention device 21B of the second embodiment, as is better understood from FIG. 4, the disk-shaped umbrella portion 22B is fixed to the fixed height h from the discharge port 15B of the bottom surface 12B by the fixing means 25B. It is fixed. The size of the umbrella portion 22B and the height (distance) h of the umbrella portion 22B from the discharge port 15B are the same as in the first embodiment. The fixing means 25B is composed of a rod-like body 26B as a column member standing upright at the center of the discharge port 15B, and the umbrella portion 22B is placed and fixed on the upper end of the rod-like body 26B. The rod-like body 26B is fixed to the discharge port 15B by a lower horizontal shaft portion 27B.

  A liquid storage tank 10C of the third embodiment shown in FIG. 5 includes a tank body 11C and a bubble mixing prevention device 21C. The tank body 11C has the same configuration as the tank body 11A of the first embodiment. Reference numeral 12C is a bottom surface, 13C is a base, 14C is a lid, 15C is a discharge port, and 16C is a liquid injection port.

  In the bubble mixing prevention device 21C of the third embodiment, as can be better understood from FIG. 6, the disk-shaped umbrella portion 22C is fixed from the discharge port 15C of the bottom surface 12C by a fixing means 25C made of a plate-like body. The height h is fixed. The size of the umbrella portion 22C and the height (distance) h of the umbrella portion 22C from the discharge port 15C are the same as those in the first embodiment. The fixing means 25C is constituted by parallel plate-like bodies 26C and 26C as column members standing on both edges of the discharge port 15C, and the umbrella portion 22C is mounted on the upper ends of the plate-like bodies 26C and 26C. It is fixed.

  A liquid storage tank 10D of the fourth embodiment shown in FIG. 7 includes a tank body 11D and a bubble mixing prevention device 21D. The tank body 11D has the same configuration as the tank body 11A of the first embodiment. Reference numeral 12D is a bottom surface, 13D is a base, 14D is a lid, 15D is a discharge port, and 16D is a liquid injection port.

  In the bubble mixing prevention device 21D of the fourth embodiment, as can be better understood from FIG. 8, an umbrella portion 22D having a rectangular plate shape in plan view is fixed from the discharge port 15D of the bottom surface 12D by a fixing means 25D. The height h is fixed. The umbrella portion 22D may be a square in plan view. The size of the umbrella portion 22D is preferably such that the planar dimension is one to five times the diameter (inner diameter) d of the discharge port 15D. If it is smaller than the above range, the upper part of the discharge port 15D cannot be reliably covered, and a vortex is formed above the discharge port 15D when the liquid is discharged, making it difficult to obtain the effect of preventing entrainment of bubbles. On the other hand, if it is larger than the above range, the umbrella portion 22D becomes too large, which is not only inconvenient in the design of the tank, but also increases the member cost. The height (distance) h of the umbrella portion 22D from the discharge port 15D is the same as that in the first embodiment. The fixing means 25D is constituted by plate-like bodies 26D and 26D as column members standing in parallel to both edges of the discharge port 15D, and the umbrella portion 22D is mounted on the upper ends of the plate-like bodies 26D and 26D. It is fixed.

An embodiment of a liquid storage tank that stores polyisocyanate, which is a liquid raw material of a polyurethane resin foam, will be described. A liquid containing tank is provided by providing the bubble mixing prevention device 21A shown in FIGS. 1 and 2 at the discharge port of the tank body having a cross-sectional area of 5.1 m ² , a height of 2044 mm, and a discharge port having an inner diameter of 80 mm at the bottom center. Configured. The disc-shaped umbrella part has a diameter (D in FIG. 2) of 240 mm (three times the diameter of the discharge port (d in FIG. 2)), and the upper end of the umbrella part from the upper end of the drain port (the drain port on the bottom of the tank). The height (h in FIG. 1) is 50 mm. To this liquid storage tank, toluene diisocyanate (T-80, isomer ratio 80:20, viscosity 3 mPas at 25 ° C.) was charged as polyisocyanate from the bottom of the tank to a height of 1635 mm. And it was made to transfer at 27000 g / min with a transfer pump (capacity: 30000 g / min, manufactured by Teikoku Pump Co., Ltd.) connected to the drain port, and the height of the liquid (toluene diisocyanate) in the tank became the first 30%. At the time, the presence of bubbles was visually confirmed in the transferred liquid (toluene diisocyanate), and no bubbles were found to be mixed.

It is a longitudinal cross-sectional view of the liquid storage tank which concerns on 1st Embodiment of this invention. It is the perspective view and sectional drawing of the bubble mixing prevention apparatus in the 1st embodiment. It is a longitudinal cross-sectional view of the liquid storage tank which concerns on 2nd Embodiment. It is the perspective view and sectional drawing of the bubble mixing prevention apparatus in the 2nd Embodiment. It is a longitudinal cross-sectional view of the liquid storage tank which concerns on 3rd Embodiment. It is the perspective view and sectional drawing of the bubble mixing prevention apparatus in the 3rd Embodiment. It is a longitudinal cross-sectional view of the liquid storage tank which concerns on the 4th Embodiment. It is the perspective view and sectional drawing of the bubble mixing prevention apparatus in the 4th Embodiment. It is a longitudinal cross-sectional view of the conventional liquid storage tank.

Explanation of symbols

10A, 10B, 10C, 10D Liquid storage tank 11A, 11B, 11C, 11D Tank main body 15A, 15B, 15C, 15D Discharge port 21A, 21B, 21C, 21D Air bubble mixing prevention device 22A, 22B, 22C, 22D Umbrella 25A, 25B, 25C, 25D fixing means

Claims (3)

In a liquid storage tank having a discharge port on the bottom,
A liquid storage tank comprising an air bubble mixing prevention device comprising an umbrella portion covering an upper portion of the discharge port and a fixing means for positioning the umbrella portion at a certain height from the discharge port.   The liquid storage tank according to claim 1, wherein a distance between the discharge port and the umbrella is 20 to 80 mm. The liquid storage tank according to claim 1, wherein the umbrella portion has a disk shape having a diameter that is 1 to 5 times the diameter of the discharge port.

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