JPH0882113A - Low temperature liquefied gas tank - Google Patents

Abstract

PURPOSE: To provide a low temperature liquefied gas tank which reduces load requirements for a storage tank main body and reduces the consumption of concrete or the like and eliminates the need for the installation of a lateral side heater tube and can shorten a construction period at low cost and facilitates maintenance work as well CONSTITUTION: In a low temperature liquefied gas tank 1, the inside of a lateral part cut-off wall 5 installed in a ground 3 is excavated so that a base cut-off wall 7 is installed on the base. Water 29 filled up in a water storage space 27 between a storage tank 9 loaded on crushed stones 13 which have filled up the base and the lateral part cutoff wall 5 and the base cut-off wall 7, is transferred or heat-circulated between a temporary storage and heating tank 37 by means of a pump and a pipeline, thereby controlling a water level and temperature. The loading requirements for the skeleton of the storage tank 9 is minimized by balancing the external pressure with the internal pressure of a low temperature liquefied gas 21 by way of water level control and a freezing line in the low temperature liquefied gas tank main body 1 and its surrounding area 3 is controlled by way of temperature control.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low temperature liquefied gas tank for storing LNG and the like underground.

[0002]

2. Description of the Related Art Generally, there is an underground tank for storing low-temperature liquefied gas such as LNG.

FIG. 3 is a structural explanatory view showing an example of a conventional low temperature liquefied gas tank 51.

A water stop wall (continuous underground wall) 55 is provided in the ground 53, the inside of the water stop wall 55 is excavated, and a bottom filling crushed stone 57 is placed at the center of the bottom of the excavation space to fill the bottom. Crushed stone 5
A storage tank 59 is placed on the upper side of 7. The main body of the storage tank 59 is made of storage tank skeleton concrete 61, and a heat insulating material 63 and a membrane 65 are provided on the entire inner surface. This storage tank 59
The low-temperature liquefied gas 67 is stored in the internal space of the, and the liquid level gauge 69 is floated on the top of the low-temperature liquefied gas 67. A roof 71 is placed on the upper side of the storage skeleton concrete 61.

A predetermined number of pumping pumps 73 are installed around the bottom-filled crushed stones 57, and a pumping pipe 75 extends from each pumping pump 73 to a level above the ground surface in a pumping pit 77. A side heater pipe 79 is provided between the side storage tank skeleton concrete 61 and the water blocking wall 55, and the pumping pit 7 is provided.
7 and the periphery of the side heater tube 79 are backfilled with backfill soil 81 and the like. In this example, by providing the bottom water stop wall 90, even if the inside of the buried soil 81 is restored to the natural water level, the underground spring from the bottom is drained by the pumping pump 73, so that the skeleton concrete 61 at the bottom is applied. Reduce pressure. However, conventionally, the bottom water stop wall 90 was not installed and the storage tank 5
There are many underground low-temperature liquefied gas tanks of the type in which both earth pressure and water pressure are applied to the 9 and the water blocking wall 55. In this case, the pumping pump 73 plays the role of a bottom hot water circulation heater after the operation of the storage tank is lowered and the water level of the spring etc. is lowered.

[0006]

However, in the conventional low temperature liquefied gas tank 51, regardless of the liquid depth of the low temperature liquefied gas 67 in the storage tank 59, the backfill soil is always backfilled on the outer surface of the side wall of the storage tank skeleton concrete 61. Earth pressure and water pressure such as 81 are applied, and it is necessary to set the frame strength that can withstand these external pressures. Therefore, as the storage tank 59 has a larger capacity, the strength of the storage tank skeleton concrete 61 itself needs to be improved and the thickness of the storage tank skeleton concrete 61 needs to be increased, resulting in an increase in cost.

Further, in order to control the freezing lines of the storage skeleton concrete 61 of the low temperature liquefied gas tank 51, the water blocking wall 55, the surrounding ground 53, etc., it is necessary to install the side heater pipe 79 around the periphery. It was

The present invention has been made in view of the above problems, and an object of the present invention is to reduce the load condition of the storage tank main body and the ground without sacrificing safety and to reduce the amount of concrete or the like used. Another object of the present invention is to provide a low temperature liquefied gas tank that can be reduced in number, eliminates the need for side heater pipe installation and backfilling, shortens the construction period, has low cost, and is easy to maintain.

[0009]

In order to achieve the above-mentioned object, the present invention provides a water stop wall or a water stop film for preventing the permeation of groundwater from the side and the bottom, and a water stop wall provided inside the water stop wall. A low-temperature liquefied gas tank comprising a skeleton including side walls and a bottom plate, and a roof provided on the skeleton, and water is charged between the water blocking wall and the skeleton.

[0010]

In the present invention, water is stored in the water storage space between the water blocking wall or the water blocking film that prevents the permeation of groundwater from the side and the bottom and the side wall provided inside the water blocking wall and the skeleton composed of the slab. To load. The water level in the water storage space is adjusted to match the liquid depth of the low-temperature liquefied gas in the storage tank, the storage tank is supported by the buoyancy of the water, and the internal and external pressures applied to the storage tank body are balanced to affect the storage tank structure. The load condition can be reduced to make the body thinner. Further, by heating the water as required, the freezing line of the body, the water blocking wall, the surrounding ground, etc. is controlled.

[0011]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a structural explanatory view of a low temperature liquefied gas tank 1. The side water stop wall 5 is provided in the ground 3, and the side water stop wall 5 is provided.
The inside of is excavated, and the bottom water stop wall 7 or the water stop film is provided at the bottom of the excavated portion. At the center of the upper surface of the bottom water blocking wall 7, the bottom-filled crushed stone 13 is placed with a predetermined thickness so that the area is almost the same as that of the bottom slab 11 of the storage tank 9 so that the bottom-filled crushed stone 13 is loaded. Build the storage tank 9. The body of this storage tank 9 is composed of a bottom plate 11 and side walls 15, and a heat insulating material 19 is provided on the entire inner surface.
And the membrane 17 is provided. The low temperature liquefied gas 21 is stored in the internal space of the storage tank 9, and the liquid level gauge 23 is floated on the uppermost part of the low temperature liquefied gas 21. A roof 25 is provided on the upper side of the side wall 15.

Storage tank 9, bottom water stop wall 7 and side water stop wall 5
The water 29 is loaded in the water storage space 27 between the water and, and the water level gauge 31 is floated on the top of the water 29. At the bottom of the water storage space 27, there is a bottom-filled crushed stone 13, water 29 is also stored in the gap between each crushed stone piece, and buoyancy acts on the storage tank 9 together with the water 29 on the side surface. A predetermined number of pumps 33 are installed in the vicinity of the bottom filled crushed stone 13 at the bottom of the water storage space 27,
The other end of the pumping pipe 35 connected to each pumping pump 33 is extended into the temporary storage and heating tank 37. A heating coil 39 and a predetermined number of water return pumps 41 are provided in the temporary storage and heating tank 37. The other end of the water return pipe 43 connected to each water return pump 41 extends to the lower portion of the water storage space 25.

In this low temperature liquefied gas tank 1, water 29
Circulates between the water storage space 27 and the temporary storage and heating tank 37, and the water level and temperature are controlled.

The storage tank 9 receives buoyancy from the water 29, but the water 29 is kept so that the storage tank 9 is softly attached to the bottom filling crushed stone 13.
Water level is controlled. Therefore, the pressure applied to the bottom slab 11 and the side wall 15 that are the body of the storage tank 9 is such that the conventional low temperature liquefied gas tank 51 is backfilled with soil as shown in FIG.
Since it is less than the pressure applied to the frame of the above, the bottom plate 11 and the side wall 15 can be made thinner than before.

The data from the liquid level gauge 23 showing the fluctuation of the liquid level of the low temperature liquefied gas 21 is sent to a control device (not shown),
According to an instruction from the control device, the operation of the pump pump 33 and the return pump 41 is controlled to adjust the water level in the water storage space 27. For safety, the water level of the water 29 is adjusted within a predetermined allowable range so as to be slightly higher than the liquid level of the low temperature liquefied gas 21, and the external pressure and the internal pressure of the storage tank 9 are balanced.

Further, as shown in FIG. 3, in the conventional low temperature liquefied gas tank 51, a side heater pipe 79 is installed in order to control freezing lines such as the storage skeleton concrete 61, the water blocking wall 55 and the surrounding ground 53. It had been. On the other hand, in the low temperature liquefied gas tank 1, the water 29 is temporarily stored in the heating tank 37 by the heating coil 39 to heat the water storage space 27.
The bottom plate 11 and the side wall 1, which are the skeletons of the storage tank 9,
5, the side water stop wall 5, the bottom water stop wall 7, and the surrounding ground 3 and the like are controlled. Further, an emergency bottom heater tube or the like (not shown) may be provided in case the heating of the water 29 in the water storage space 27 is not sufficient.

The procedure for adjusting the buoyancy balance of the low temperature liquefied gas tank 1 and the temperature of the water 29 will be described below. FIG. 2 is a flowchart showing buoyancy balance adjustment and temperature adjustment. Data such as the shape, volume and weight of the storage tank 9 of the low temperature liquefied gas tank 1 is input to the computer (step 101). Based on these data, in order to balance the buoyancy of the storage tank 9, the relationship between the allowable depth of the water depth of the water storage space portion 27 and the change in the liquid depth of the stored liquid in the storage tank 9 is shown. Calculate (step 102).
Next, the water storage space 27 is provided so that the maximum capacity of a pump (not shown) used for taking in and out the stored liquid in the storage tank 9 can be dealt with.
The capacities of the water pump 33 and the return pump 41, which are the water depth adjusting pumps, are determined (step 103). Next, the data obtained in step 102 and step 103 are
The pump is set in the control device that controls the operation and stop of the pump 33 and the return pump 41 (step 10).
4).

Next, while the side wall 15 is being poured into the skeleton concrete, the water 29 is gradually loaded into the water storage space 27, and the water level gauge 31 is floated on the uppermost portion of the water 29, and the casting is performed by then. The low-temperature liquefied gas tank 1 is completed while controlling the water level with the control device, the pump 33, and the return pump 41 so as to balance with the above-mentioned portion.

After the low temperature liquefied gas tank 1 is completed, constant monitoring control is started. In the constant monitoring control, the temperature in the water storage space 27 is constantly monitored and controlled, and the change in the amount of stored liquid accompanying the inflow or withdrawal of the low temperature liquefied gas 21 is monitored and the water storage space 27 is adjusted so as to be in balance with the stored liquid amount. The water level inside is constantly monitored and controlled.

First, the low-temperature liquefied gas 21 is stored in the storage tank 9 while balancing the water levels in the water storage space 27, and thereafter the storage amount is increased or decreased as necessary.
At this time, the water temperature of the water storage space 27 and the temperature of the skeleton of the storage tank 9 are constantly measured at a plurality of predetermined measurement points (not shown) (step 105).

Next, it is judged whether or not the body temperature and the water temperature are above the optimum temperature (step 106). If the body temperature and the water temperature are below the optimum temperature, the water 29 for the water storage space 27 is temporarily stored and heated in the heating tank 37. It is heated by the internal heating coil 39 and circulated in the water storage space 27 (step 107).

In step 106, if the skeleton temperature and the water temperature are the appropriate upper limits, the heating of the water 29 for the water storage space 27 is stopped (step 108). If it is not heated in step 108, the unheated state is maintained. Next, the liquid depth of the low temperature liquefied gas 21 is measured, and the data is sent to the control device (step 109).

After step 107, the water storage space 2
Without waiting for the water temperature of 7 and the body temperature of the storage tank 9 to rise, the liquid depth of the low-temperature liquefied gas 21 is measured while the water 29 is being heated and circulated, and the data is sent to the control device (step 109), and the stored water is stored if necessary. The water level of the space 27 is adjusted. And
The water depth of the water storage space 27 that matches the liquid depth of the low temperature liquefied gas 21 measured in step 109 is calculated (step 11
0).

Next, the water depth of the water storage space 27 is measured (step 111), and it is determined whether the water depth is within an allowable range where the liquid depth of the low temperature liquefied gas 21 and the water depth of the water storage space 27 are balanced. (Step 112). If they are in equilibrium in step 112, the process returns to step 105, and while controlling the temperature, the change in the liquid depth accompanying the inflow or withdrawal of the low temperature liquefied gas 21 is continued to be monitored. If the water levels in the water storage space 27 are high, the pumping pump 33 is operated, and if the water level in the water storage space 27 is low, the return pump 41 is operated to adjust the water level of the water 29. To do. At this time, if the body temperature and the water temperature are less than the optimum temperatures in step 106, it means that the water 29 is being heated and circulated, so that the pumping pump 33 and the return water pump 41,
By adjusting the start / stop of the operation of each pump, water 29
The water level of the water storage space 27 is raised or lowered while circulating. At this time, always make the water level higher than the liquid level so that buoyancy can be balanced safely.

As described above, according to this embodiment, the side water stop wall 5, the bottom water stop wall 7, the side water stop wall 5, and the bottom water stop wall prevent the permeation of groundwater from the side and bottom. 7 is filled with water 29 in the water storage space 27 between the side wall 15 and the slab composed of the bottom plate 11, and the low temperature liquefied gas 21 in the storage tank 9 is charged.
The water level of the water storage space 27 is adjusted so as to be balanced with the liquid depth of the storage tank 9 so that the storage tank 9 is in the soft-seated bottom state. Also, water 2
By heating 9 as necessary, the side wall 15 and the bottom plate 11
It is possible to control the icing lines in the frame consisting of, the side water blocking wall 5, the bottom water blocking wall 7 and the surrounding ground 3. Further, since the outer peripheral portion of the skeleton of the storage tank 9 can be visually inspected from the water storage space 27, maintenance is facilitated.

[0027]

As described above in detail, according to the present invention, the load condition of the storage tank main body and the ground is reduced to reduce the usage amount of concrete etc. without impairing the safety and the side heater. It is possible to provide a low-temperature liquefied gas tank that does not require pipe installation and backfilling, can shorten the construction period, is low in cost, and is easy to maintain.

[Brief description of drawings]

FIG. 1 is a structural explanatory view of a low temperature liquefied gas tank 1.

FIG. 2 is a flowchart showing buoyancy balance adjustment and temperature adjustment.

FIG. 3 is a structural explanatory view of a conventional low temperature liquefied gas tank 51.

[Explanation of symbols]

 1 ...... Low temperature liquefied gas tank 3 ...... Ground 5 ...... Side water stop wall 7 ...... Bottom water stop wall 9 ...... Storage tank 11 ...... Bottom plate 13 ...... Bottom filling crushed stone 15 ...... Side wall 17 ... Membrane 19 ... Insulation 21 ... Low-temperature liquefied gas 23 ... Level gauge 25 ... Roof 27 ... Water storage space 29 ... Water 31 ... Water level 33 Pumping pump 35 Pumping pipe 37 Temporary storage and heating tank 39 Heating coil 41 Return pump 43 Return pipe

Claims (3)

[Claims] 1. A water blocking wall or a water blocking film for preventing permeation of groundwater from the side and bottom, a frame provided inside the water blocking wall, the frame including a side wall and a bottom slab, and a roof provided on the frame. A low-temperature liquefied gas tank, characterized in that water is loaded between the water blocking wall and the skeleton. 2. The low temperature liquefied gas tank according to claim 1, wherein the amount of the water is changed according to the amount of the low temperature liquefied gas stored inside the body. 3. The low temperature liquefied gas tank according to claim 1, wherein the water is heated and used as a heater.