JP4014743B2 - Pump pit for tank - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a tank pump pit that is provided at a predetermined depth from the bottom surface of a tank and accommodates a liquid discharge pump. In particular, even when the tank expands and contracts depending on the temperature of liquid to be stored, It relates to a membrane that does not place a burden on the membrane.
[0002]
[Prior art]
In general, in a membrane type low temperature tank, a liquid discharging pump is installed in a pump barrel in the tank. FIG. 5 is a cross-sectional view showing a conventional tank. This tank is an underground storage type low temperature tank for storing LNG, LPG, etc., and a membrane (not shown) is disposed on the inner surface of the casing 101. The liquid discharge pump 102 is housed in the lower end of the barrel 104 penetrating the roof 103, and sucks LNG from the lower end of the barrel 104.
[0003]
For example, in the case of a tank having a liquid depth of 35 m, the pump 102 cannot discharge the liquid by sucking vortices and bubbles unless the liquid level is at a height H of about 2 to 3 m from the suction port. That is, the liquid corresponding to the position and height H of the pump 102 cannot be dispensed from the tank, resulting in a decrease in the effective storage amount of the tank. In order to cope with this, it is conceivable to form a tank pump pit as shown in FIG.
[0004]
This is because a hole 106 is formed in the bottom 101a of the casing 101, and a bottomed cylindrical pit body 107 is installed in the hole 106 via a cold insulating material (for example, polyurethane foam) 108. By disposing the lower end portion of the barrel 104 in 107 and lowering the installation position of the pump 102, the liquid discharge amount is increased and the effective storage amount is increased. Note that the upper end of the pit body 107 is connected to the membrane 105.
[0005]
[Problems to be solved by the invention]
In the conventional tank pump pit described above, the pit main body 107 is simply installed in the hole portion 106. Therefore, when a low temperature liquid such as LNG is stored, the pit main body 107 is heated downward with the bottom as a reference. As shown in FIG. 6B, the membrane 105 is contracted and deformed so as to be pulled downward. The membrane 105 is provided with a cross-sectional chevron portion (not shown) for absorbing deformation (stretching) in the in-plane direction, usually called corrugation.
[0006]
However, if the membrane 105 is deformed in an out-of-plane direction that bends downward as described above, the peripheral corrugation is likely to exhibit unstable behavior, and as a result, the basic performance of the tank may be hindered. Absent. Conversely, when storing a high-temperature liquid, the pit body thermally expands upward and deforms so as to lift the membrane 105 upward, so that the membrane 105 is similarly deformed out of plane.
[0007]
The present invention has been made in view of such problems, and does not cause the membrane to be deformed in the out-of-plane direction even when the pit body is thermally contracted or expanded due to the temperature of the liquid stored in the tank. Then, it aims at providing the pump pit for tanks which can clarify the behavior of a membrane and corrugation.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention according to claim 1 is a tank pump that is provided at a predetermined depth from a bottom surface of a tank formed by disposing a membrane on the inner surface of the housing and accommodates a liquid discharge pump. It is a pit composed of a hole provided at a predetermined position on the bottom of the housing, and a bottomed cylindrical pit main body that is installed in a state of being connected to the membrane and suspended from the opening end of the hole , pit body, a technique bottom depending on the thermal contraction or thermal expansion Ru is installed movably in upward or downward is adopted. In this tank pump pit, the pit body is grounded while being suspended from the opening end of the hole, so even if the pit body is thermally contracted or expanded due to the temperature of the liquid stored in the tank, the pit body When the main body contracts or expands with the connection portion with the membrane as a reference, the bottom portion moves upward or downward . Therefore, the corrugation behavior can be clarified without causing the membrane to be deformed in the out-of-plane direction, and the basic performance of the tank can be maintained.
[0009]
The invention according to claim 2 is applied to the tank pump pit according to claim 1, in which the pit body is formed with a semicircular or semi-elliptical bottom as viewed from the side . In this tank pump pit, the bottom of the pit body is formed in a semicircular or semi-elliptical shape when viewed from the side, so that it is possible to easily cope with the hydraulic pressure applied to the bottom of the pit body, It is possible to ensure the strength of the pit body installed in the state.
[0010]
The invention according to claim 3 is applied to the tank pump pit according to claim 1 or 2 in which an annular support is disposed between the opening end of the hole and the pit body. In this tank pump pit, the pit body is suspended from the opening end of the hole through an annular support, so even if a cold insulator or the like is inserted between the hole and the pit body, the support is provided. Accordingly, the upper end of the pit body can be connected to the opening end of the hole, and the suspended state of the pit body can be secured.
[0011]
The invention according to claim 4 is the tank pump pit according to claim 3, in which the support is formed by connecting two annular bodies with a plurality of ribs. In this tank pump pit, the support is formed by connecting two annular bodies with a plurality of ribs, so that a cold insulator or the like is inserted between the two annular bodies while locking the upper end of the pit body. For example, in the case of a low-temperature tank or the like, the basic performance of the tank can be maintained by disposing the cold insulating material without breaks.
[0012]
The invention according to claim 5 is applied to the tank pump pit according to claim 1, wherein the pit body is installed between corrugations formed in the membrane. In this tank pump pit, since the pit main body is installed between the corrugations formed on the membrane, it is possible to absorb the contraction or expansion in the bottom direction of the upper end portion of the pit main body by the peripheral corrugation.
[0013]
The invention according to claim 6 is applied to the tank pump pit of claim 1, 2, 3, 4, or 5 in which the pump is accommodated while being shifted from the center of the pit body. In this tank pump pit, the pump is housed away from the center of the pit body, so that it is possible for the operator to secure a gap that enters the pit body, and avoids making the pit body larger than necessary. It becomes possible to do.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view showing a tank pump pit according to the present invention. The tank to which this tank pump pit is applied is, for example, a low-temperature liquid storage underground tank such as LNG or LPG as shown in FIG. 5, but is not limited thereto, and may be a ground tank. This tank is constructed by a concrete segment, and a hole 2 is formed in the bottom 1 of the casing. The hole 2 is provided at a position where the lower end of the barrel 4 that accommodates the pump 3 can enter, for example, at a position below the barrel 4 in the vertical direction.
[0015]
As shown in FIGS. 1 and 2, a membrane 6 having a cross-sectional mountain-shaped corrugation 7 is laid on the bottom 1 via a cold insulating material 5 such as polyurethane foam. And the part corresponding to the hole part 2 of the membrane 6 is notched, and the hole part 2 is exposed. The membrane 6 is preliminarily calculated and laid so that the position where the membrane 6 is cut out is between the corrugations 7. As the membrane 6, a stainless plate having a thickness of about 2 mm is used, and corrugations 7 are formed in a lattice shape.
[0016]
An annular support 8 is installed on the open end 2 a of the hole 2. As shown in FIG. 3, the support 8 is formed by connecting a plurality of annular bodies 9, 10 with a plurality of ribs 11 at a predetermined interval. The height of the support 8 is set according to the thickness of the cold insulating material 5 laid on the bottom 1. Therefore, as shown in FIG. 1, by placing the support 8 on the opening end 2 a, the upper surface of the annular body 9 is flush with the upper surface of the cold insulating material 5.
[0017]
Further, similarly to the cold insulating material 5, a cold insulating material 12 such as polyurethane foam is provided on the inner surface of the hole 2. Then, by setting the inner diameter of the annular body 9 in consideration of the thickness of the cold insulating material 12, the upper surface of the annular body 9 becomes a reference position instead of the opening end 2 a of the hole portion 2.
[0018]
As shown in FIG. 1, a pit body 13 is installed on the support 8. The pit body 13 is made of a stainless steel plate having a thickness of about 10 mm so as to withstand the hydraulic pressure, and has an outer diameter matching the inner diameter of the support 8 and is formed into a bottomed cylindrical shape in consideration of the depth of the hole 2. The upper end is provided with a flange 14 facing outward. The bottom portion 15 of the pit body 13 is formed in a semi-elliptical shape so as to withstand the hydraulic pressure, but may be semi-circular, tapered, or flat plate instead.
[0019]
Then, by placing the flange 14 on the upper surface of the support 8, the pit body 13 is installed in a state of being suspended in the hole 2. The flange 14 and the membrane 6 are connected by welding or the like. It can be considered that the support 8 on which the flange 14 is placed is placed on the opening end 2a and hardly displaced in the vertical direction. Therefore, the pit main body 13 can consider expansion and contraction or expansion considering the flange 14 portion, that is, the connection portion with the membrane 6 as a reference position.
[0020]
The support 8 and the flange 14 are not fixed so that the support 8 does not restrain the pit body 13 from contracting in the horizontal direction (the tank bottom surface direction). Further, the gap 16 between the cold insulating material 12 and the pit body 13 is filled with glass wool, pearlite, or the like.
[0021]
As shown in FIG. 1, the pump 3 is arranged in a state of being accommodated in the pit body 13 by inserting the lower end of the barrel 4 into the pit body 13. The pump 3 includes a lid portion 3b that opens and closes by operating the driving portion 3a to form a liquid suction port. By opening the lid portion 3b and sucking in liquid as indicated by an arrow, the liquid is It is paid out of the tank through the barrel 4.
[0022]
The pump 3 (barrel 4) is arranged so as to be shifted from the center of the hole 2 as shown in FIGS. This is because it is possible to form a gap into which an operator enters by shifting the pump 3, and there is an advantage that it is not necessary to provide a hole 2 larger than necessary. However, it is arbitrary whether the pump 3 is shifted from the center of the hole 2.
[0023]
Next, a case where the tank pump pit configured as described above receives LNG from an empty tank will be described. LNG is a low temperature liquid of about −162 ° C., and accepting this LNG causes thermal contraction in the pit body 13. FIG. 4 shows a state in which the pit main body 13 is thermally contracted. Thus, the pit main body 13 is in a state in which the flange 14 is suspended by being supported by the support 8. As the bottom 15 moves upward.
[0024]
Therefore, since the flange 14 which is a connecting portion with the membrane 6 does not move in the vertical direction, the membrane 6 does not cause out-of-plane deformation, and the membrane 6 and the peripheral corrugation 7 exhibit unclear behavior. It is preventing. As described above, the membrane 6 is effectively prevented from being deformed in the out-of-plane direction while the installation position of the pump 3 is lowered to increase the liquid discharge amount. In addition, after paying out LNG from the tank, the pit body 13 is released from the heat contraction and returns to the original state shown in FIG.
[0025]
Further, the pit body 13 is thermally contracted not only in the vertical direction but also in the radial direction. This radial thermal contraction is considered as deformation in the in-plane direction in the membrane 6 because the flange 14 is connected to the membrane 6. And is appropriately absorbed by the peripheral corrugation 7.
[0026]
In the above-described tank pump pit, the liquid to be stored is a low-temperature liquid such as LNG, and the pit body 13 is also set in consideration of thermal contraction, but not only stores such a low-temperature liquid. Even when a high-temperature liquid is stored, the tank pump pit according to the present invention can be applied. In this case, the pit body 13 is thermally expanded with the flange 14 as a reference position as described above. Therefore, it is necessary to previously form a predetermined gap between the bottom 15 of the pit body 13 and the bottom surface of the hole 2 at room temperature. This is because when the pit body 13 is thermally expanded as the liquid is received, the downward movement of the bottom portion 15 is allowed by the gap.
[0027]
Further, the shapes, combinations, and the like of the constituent members shown in the above embodiments are merely examples, and various modifications can be made based on design requirements and the like without departing from the spirit of the present invention. For example, the form of the support 8 is arbitrary, and any support can be used as long as it can be disposed between the opening end 2a of the hole 2 and the flange 14 of the pit body 13, and the support 8 is not limited to an annular member. Furthermore, the structure which installs the pit main body 13 in the opening end 2a of the hole 2 directly, without using the support 8 may be sufficient. In addition, a cylindrical body having a square cross section may be used as the pit body 13, and the corrugation 7 portion may be used as an installation position of the pit body 13.
[0028]
【The invention's effect】
As described above, the tank pump pit according to claim 1 is grounded in a state in which the pit main body is suspended from the opening end of the hole, and therefore, the pit main body is thermally contracted by the liquid temperature stored in the tank. Even in the case of thermal expansion, the pit body contracts or expands based on the connection part with the membrane, so that the membrane is not deformed in the out-of-plane direction, and the behavior of corrugation can be clarified. The basic performance of the tank can be maintained.
[0029]
The tank pump pit according to claim 2 can easily correspond to the hydraulic pressure applied to the bottom of the pit body because the bottom of the pit body is formed in a semicircular shape or a semi-elliptical shape. The strength of the installed pit body can be easily ensured.
[0030]
The tank pump pit according to claim 3 is a case where a pit body is suspended from the opening end of the hole portion via an annular support, and therefore, for example, a cold insulating material or the like is inserted between the hole portion and the pit body. In addition, the upper end of the pit body can be connected to the opening end of the hole through the support, and the suspended state of the pit body can be ensured.
[0031]
In the tank pump pit according to the fourth aspect of the present invention, the support is formed by connecting the two annular bodies with a plurality of ribs. For example, in the case of a low-temperature tank or the like, the basic performance of the tank can be maintained by disposing the cold insulation material without breaks.
[0032]
The tank pump pit according to claim 5 is installed between the corrugations in which the pit body is formed on the membrane, so that the connection between the pit body and the membrane (for example, welding work) is facilitated, and the upper end portion of the pit body is Shrinkage or expansion in the bottom direction can be absorbed by peripheral corrugation.
[0033]
In the tank pump pit according to the sixth aspect, the pump is accommodated while being shifted from the center of the pit main body, so that a clearance can be secured for the operator to enter the pit main body, and the pit main body is enlarged more than necessary. This can avoid the unnecessary reduction of the effective storage capacity of the tank.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of a tank pump pit according to the present invention.
FIG. 2 is a plan view of the tank pump pit shown in FIG.
FIG. 3 is a perspective view of the support shown in FIG. 1;
FIG. 4 is a cross-sectional view showing a state where a pit body is thermally contracted.
FIG. 5 is a cross-sectional view showing a general tank.
6A and 6B show a conventional tank pump pit, in which FIG. 6A is a cross-sectional view in a normal state, and FIG. 6B is a cross-sectional view in a state where a pit body is thermally contracted.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Bottom part 2 Hole part 2a Open end 3 Pump 6 Membrane 7 Corrugation 8 Support 9,10 Annular body 11 Rib 13 Pit main body 15 Bottom part

Claims (6)

A tank pump pit provided at a predetermined depth from the bottom surface of a tank formed by arranging a membrane on the inner surface of the housing, and accommodating a pump for discharging liquid,
It is composed of a hole provided at a predetermined position of the bottom of the housing, and a bottomed cylindrical pit body that is connected to the membrane and installed in a suspended state from the opening end of the hole ,
The tank pit is characterized in that the pit main body is installed in a state in which a bottom portion can move upward or downward according to thermal contraction or thermal expansion . 2. The tank pump pit according to claim 1, wherein the pit body has a semicircular or semi-elliptical bottom as viewed from the side .   3. The tank pump pit according to claim 1, wherein an annular support is disposed between the opening end of the hole and the pit body.   4. The tank pump pit according to claim 3, wherein the support is formed by connecting two annular bodies with a plurality of ribs.   5. The tank pump pit according to claim 1, wherein the pit body is installed between corrugations formed on the membrane.   6. The tank pump pit according to claim 1, wherein the pump is accommodated while being shifted from a center of the pit body.

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