JP6444585B2 - Construction method of gas storage tank and LNG tank - Google Patents

Description

  The present invention relates to a gas storage tank, for example, and more particularly to an LNG storage tank.

In a situation where energy demand in the world is increasing, the use of clean energy is attracting attention in order to cope with global environmental problems. Under these circumstances, demand for LNG (Liquid Natural Gas) is increasing rapidly because it emits less CO ₂ than oil and coal and has a long-term supply stability. Many LNG tanks are currently in operation at home and abroad to store them, but LNG tanks are always required to have high safety. Specifically, for steel materials that should form the inner tank material of the LNG tank, in addition to the high brittle cracking suppression characteristics in the LNG temperature range (−162 ° C.), the seriousness of the LNG tank destruction accident Considering the above, emphasis is placed on the brittle crack propagation stop property. From this point, a 9% Ni steel sheet having excellent low-temperature toughness has been used as an inner tank material for an above-ground LNG tank.

  Examples of the LNG tank construction technology using such steel materials include those shown in Patent Documents 1 and 2.

  In this Patent Document 1, a welded structure of 9% Ni steel having excellent strength and toughness at low temperature so that the surface in contact with LNG can withstand cold shock as an inner tank material of a double-shell LNG tank It is explained that 9% Ni steel is a material that has a low coefficient of linear expansion and can maintain LNG in a liquid state and does not cause brittle fracture even at a low temperature of −162 ° C. or lower. Yes.

  Patent Document 2 discloses the technical idea of the connection between the outer tank material and the liquid bank in the so-called PC liquid bank / outer tank integrated ground storage type LNG tank, but the nickel used in the inner tank material is disclosed. Regarding the viewpoint of using (Ni) steel, there is the same one as in Patent Document 1.

  As described in Patent Document 2, a conventional storage tank for storing LNG and LPG (Liquid Petroleum Gas) at a low temperature is generally a cylindrical flat bottom as shown in FIG. A storage tank is used. The storage tank shown in FIG. 4 in the same document includes an outer tub 103 made of PC (prestressed concrete) and an inner tub 104 made of a metal plate such as 9% Ni steel. A dome-shaped roof D is installed at the upper end of 104. The outer tub 103 has a side wall portion S formed in a cylindrical shape, and a liner plate 106 made of a thin metal plate such as carbon steel provided on the inner peripheral surface of the side wall portion S. Between the outer tub 103 and the inner tub 104, a cold insulating material (heat insulating material) 105 made of pearlite, PUF (PolyUrethane Foam) or the like is provided. The outer tub 103 maintains the strength of the entire tank, and the liner plate 106 suppresses intrusion of moisture and the like from the outside into the interior and maintains the sealing performance against the stored items.

  FIG. 5 in Patent Document 2 is a development view of the liner plate 106. As shown in FIG. 5 in the same document, the liner plate 106 is formed by connecting a plurality of metal plate members 106a having a rectangular shape in plan view, with the longitudinal direction being horizontal. As shown in FIG. 6 in the document, the end surface of the plate member 106a is an inclined surface, and a groove shape is formed by abutting the end surfaces of the adjacent plate members 106a. On the other hand, anchor members 107 are provided at a plurality of predetermined positions on the side wall portion S of the outer tub 103, and a groove-shaped butting portion (groove portion) 108 is disposed on the anchor member 107. Then, arc welding is performed on the butt portion 108, whereby each plate member 106a is fixed to the side wall portion S of the outer tub 103 via the anchor member 107, and adjacent plate members 106a are also connected to each other. The

Under such circumstances, on the other hand, the LNG tank needs to have a large capacity from the viewpoint of effective utilization of land and rationalization accompanying an increase in economic scale. At present, an LNG tank of 180,000 m ³ has been realized, but there is a tendency to demand an LNG tank having a large capacity of, for example, 230,000 m ³ . In order to meet this demand, it is possible to deal with the problem by increasing the number of materials with extra material costs and lengthening the construction process according to the scale. However, in the present situation where improvement in utilization efficiency of management resources is continuously demanded, it is ideal to carry out the construction for increasing the capacity of the LNG tank without increasing the cost. In particular, nickel (Ni) is a so-called rare metal that is not only difficult to obtain, but also consumes global environmental resources. It is also necessary to consider this point of view.

  Therefore, for example, it is conceivable to use a material having a reduced nickel (Ni) content. However, it is not preferable to reduce the design performance of the material by that amount, resulting in deterioration of the quality of the LNG tank. It is necessary to avoid not only the LNG tank but also the deterioration of the quality of the steel material used causes the deterioration of the quality.

  In addition, as the LNG tank is scaled up, the construction period is extended accordingly, contrary to the demands of the times. In other words, it is preferable that the construction period is the same or more shortened while the capacity is increased. However, if the capacity is increased, the material used increases and the process becomes congested. Since the scale of the work environment at the site increases, the number of workers increases, and the amount of work for each unit work increases accordingly, which complicates. In the case of an LNG tank, concrete is placed and this curing period is required to a certain extent depending on the concrete capacity. Considering these circumstances, generally, if the scale is increased, the construction period will be prolonged, so the request to shorten the construction period while increasing the scale of the LNG tank is such Contrary to the general trend, it must be said that it is usually difficult to realize.

JP 2007-278400 A JP 2002-128191 A

  The present invention solves such problems of the prior art, and the construction accompanying the enlargement of the LNG tank reduces the cost, reduces the safety, and substantially shortens the construction period. It aims to be realized. Furthermore, it aims also at providing the LNG tank implement | achieved in that way.

In order to achieve such an object, an LNG tank according to the present invention is composed of an outer tank in which side plates or liner plates are arranged, and a steel that is disposed at a certain distance from the outer tank and contains 7% nickel. a plurality of inner tank side plate stage configured by connecting in the circumferential direction, a plurality of stages stacked so as not to overlap said connecting line in the vertical direction, formed by welding the connecting portion in the longitudinal joint and peripheral joint comprising A bottom liner plate and a bottom liner annular plate fill the inner tank, a heat insulating layer filled with a heat insulating material between the inner tank and the outer tank, and a tank bottom defined by the inner tank and / or the outer tank. And a bottom liner layer arranged in this manner. For example, carbon steel may be used for the outer tank.

In the above, the inner tub includes a tank side plate first stage in which a plurality of inner tank side plate into the inner tank Annular plate is formed continuously connected in the circumferential direction, of the plurality of tank side plate first stage on the a tank side plate 2-stage tank side plate and the peripheral joint position of each inner tank side plate of the first stage inner tub side plate is formed by connecting in the circumferential direction as the joint position is shifted, thus successively stacked and the inner tub side plate uppermost th uppermost is, comprising a tank roof is joined via a knuckle plate in said tank side plate uppermost eyes, are welded in the circumferential joint upon articulation of said tank side plate It is more preferable that the vertical joint is constructed such that it is welded after the stiffener is attached.

  In addition, separately, in the above, the thickness of the inner tank side plate is considered as a factor at least the allowable tensile stress of the steel material containing 7% nickel, the pressure acting on the lowermost portion of the side plate, and the efficiency of the welded joint. More preferably, it is determined.

  In this case, the bottom liner layer is arranged such that a bottom liner plate and a bottom liner annular plate fill a bottom surface of the tank defined by the inner tank and / or the outer tank, and the bottom liner plate or the bottom liner annular plate is disposed on the bottom liner plate. Such plate material and plate material are formed by butt welding or fillet welding.

  Further, in the above, the inner tank includes an inner tank roof and an inner tank side plate, the outer tank includes an outer tank roof, and the inner tank roof hangs a deck plate from the outer tank roof with a suspended member. It is more preferable to cover the upper part of the inner tank side plate. That is, the inner tank roof has a so-called suspension structure.

  Further, in the above, the outer tank comprises an outer tank liner and an outer tank roof, and the outer tank roof and the inner tank roof are temporarily connected to each other by a bone support material and then floated. It is more preferable that the hanger is hung down and connected to the uppermost stage of the inner tank side plate.

  Furthermore, in the above, it is more preferable to further include a liquid breakwater made of PC (prestressed concrete) in which a compressive force is previously applied to the PC steel material in a substantially vertical direction and a circumferential direction. The breakwater is provided for LNG leakage in the unlikely event that a leak detection facility and various disaster prevention facilities can be further installed.

  Furthermore, the heat insulating material has a structure including pearlite, pearlite concrete, PUF (polyurethane foam), foam glass, glass wool or the like at the bottom and / or roof and / or sides.

  Moreover, you may make it further provide the bottom part cold insulation layer by which the perlite concrete which laid the metal-mesh on the said bottom liner annular plate was laid in multiple layers.

  First, the present inventor has focused on whether 7% nickel steel can be used instead of the conventional 9% nickel steel as the inner tank material. At this time, since it was necessary to avoid the above-mentioned quality deterioration, the ingenuity was devised in order to prevent the quality from being hindered even if 7% nickel steel was used. From this point of view, the ingenuity was repeated so that safety would not be affected even if the tank capacity was increased. More specifically, the inner tank was devised to take a configuration that can realize a safe structure against the internal pressure and the external pressure.

  In addition, the breakwater can not only withstand combined loads of normal load (self-weight, pre-stress force, restraint load), seismic load, wind load, hydraulic pressure, and thermal load that increase as the capacity increases. As a countermeasure against liquid leakage due to an increase in internal pressure due to enlarging, the welding mode of the plate material was devised.

  Steel containing 7% nickel used for the inner tank is a material that has a certain level of low temperature toughness. The steel containing 7% nickel was judged to have sufficient accuracy as an LNG inner tank plate material constituting the invention of the present application as a result of impurity reduction, ingenuity of the manufacturing method, and the like. This is due to the improvement in low-temperature toughness in the base metal and welded joint resulting from an increase in the fine retained austenite phase, which was brought about by means of steelmaking. There is also a secondary effect unique to the present application which is brought about by using 7% nickel steel as an inner tank plate of a LNG tank which is enlarged. That is, the consumption of nickel, which is a so-called rare metal, is relatively reduced, which contributes to the protection of the global environment. Furthermore, since these rare metals are used, the cost reduction is achieved by reducing the nickel content, which is an international price trend affecting the industry trend. This point has a significant industrial impact.

  The inner tank has a flat bottom cylindrical saddle-shaped tank shape with a (dome-shaped) roof excellent in earthquake resistance. This is because it directly bears the storage and preservation of LNG that requires a high level of safety. A cold insulator, which will be described later, is arranged and installed on the side of the inner tank.

The breakwater has a function to prevent leakage of liquids such as LNG from leaking to places other than its facilities and equipment, and usually with PC (prestressed concrete). It is common to be manufactured. PC is a PC steel material in which a compressive force is applied to the concrete member before the load is applied (prestressed), and the tensile stress is not generated in the concrete when the load is applied. The stress can be controlled. Concrete has a characteristic that it is strong in compressive force and weak in tensile force, but this is compensated to prevent cracking due to tensile stress compared to reinforced concrete. The above-mentioned loads include own weight (inner tank, outer tank, cold insulation material, piping, equipment accessories' own weight), inner tank gas pressure, gas pressure between inner and outer tanks, static liquid pressure, cold insulation material pressure (cold insulation material between inner and outer tanks) The pressure and friction force acting on the side plates of the inner tank or the outer tank), the thermal (temperature) load (the load acting on the inner tank due to the temperature shrinkage of the piping), and the snow load (in the case of a heavy snow region) are taken into consideration. The breakwater needs to be able to exhibit not only a function from a structural viewpoint but also a function of preventing leakage from the inner tank. For example, liquid leakage corresponding to a capacity of 230,000 m ³ should occur from the inner tank, and even when the corresponding liquid pressure acts on the breakwater, it is necessary to ensure liquid tightness. For this purpose, a configuration in which a compressive force is applied in advance to the above-described PC steel material in a substantially vertical direction and a circumferential direction is employed. In addition, as a liquid barrier made of a concrete structure, it is not restricted to PC, RC (steel reinforced concrete), SRC (steel reinforced concrete), etc. may be used. In this case, it is a condition that necessary strength can be expressed. Alternatively, PCa (precast concrete) may be used, for example, a structure realized by a method in which a precast formwork integrated with an outer tub material is loaded inside the liquid barrier.

  The outer tub is constituted by a side liner plate arranged so as to be directly or indirectly inscribed in the liquid barrier. The side liner plates are configured in multiple stages, and in each stage, the liner plates are joined in the circumferential direction. In order to suppress the evaporation of LNG, the inner tank side portion and the roof portion are filled with a cold insulating material such as granular pearlite, and nitrogen gas for moisture prevention is enclosed. The outer tub holds such a cold insulating material and has a function of sealing nitrogen gas. The outer tub roof edge is fixed to the top of the breakwater.

According to the above configuration, by using a liquid bank made of PC (prestressed concrete) that has been preliminarily compressed in the vertical direction and circumferential direction with respect to the PC steel material, Even when leakage occurs, a sufficient resistance to hydraulic pressure can be maintained. Further, in the inner tank, a plurality of inner tank side plate formed by 7% nickel steel stage formed are connected in the circumferential direction, a plurality of stages stacked so as not to overlap said connecting line in the vertical direction, the connecting portion As a result of being welded in vertical joints and circumferential joints, the material strength of the base metal and joints is ensured without affecting quality even if the conventional 9% nickel steel is replaced with 7% nickel steel. Safety performance equivalent to or better than that can be achieved.

Here, as the inner tank, a plurality of inner tank and the tank side plate first stage in which a plurality of inner tank side plate is formed by connecting in the circumferential direction, into the inner tub side plate first stage on the inner tank Annular plate a tank side plate 2 stage formed by being articulated in the circumferential direction as the joint position shifts to the peripheral joint position of each inner tank side plate of the first stage inner tub side plate side plate, thus are sequentially stacked and the inner tub side plate uppermost th uppermost Te, comprising a tank roof is joined via a knuckle plate in said tank side plate top th vertical welded in the circumferential joint upon articulation of said tank side plate In addition to the above effects, the joint can be made to have a strong load resistance by being configured to be welded after the stiffener is attached to the joint.

  Further, the thickness of the inner tank side plate is determined taking into account factors such as at least the allowable tensile stress of the steel material containing 7% nickel, the pressure acting on the lowermost portion of the side plate, and the efficiency of the welded joint. With this configuration, the strength can be ensured in a more visible form and can be verified.

  Furthermore, the bottom liner layer is arranged so that a bottom liner plate and a bottom liner annular plate fill a tank bottom defined by the inner tank and / or the outer tank, and the bottom liner plate or the plate material related to the bottom liner annular plate The portion where the plate and the plate material meet is groove-welded, and the portion where the three plate materials are stacked is the top material on the plate thickness portion formed by the overlap of the bottom material and the intermediate material is fillet welded By adopting a structure in which the layers are layered so as to cover them, even if the conventional 9% nickel steel is replaced with 7% nickel steel, the safety performance equal to or higher than that is realized without causing any problem in quality.

  The outer tank comprises an outer tank liner and an outer tank roof, and the inner tank roof is suspended after the outer tank roof and the inner tank roof are temporarily connected and floated by a bone support material. Thus, the inner and outer roofs can be lifted at the same time by being connected to the uppermost stage of the inner tank side plate, and the construction period can be shortened.

  A function of maintaining a constant temperature at the bottom of the tank is realized by further including a bottom cold insulation layer in which a plurality of layers of pearlite concrete laid with a wire mesh on the bottom liner annular plate is placed.

In the LNG tank according to the present invention, even when the capacity scale is increased (for example, 230,000 m ³ ), the cost can be suppressed from increasing with the scale, and the construction period can be substantially shortened. Become.

  In particular, the cost can be substantially reduced, and constant quality can be maintained and safety can be maintained and improved.

It is a schematic sectional drawing of the LNG tank (construction) 1 which concerns on one Embodiment of this invention. It is the conceptual perspective view which showed the process which concerns on construction of the inner tank side board among the LNG tank (construction) 1 which concerns on one Embodiment of this invention. It is the conceptual perspective view which showed the process which concerns on the knuckle plate attachment of the LNG tank (construction) 1 which concerns on one Embodiment of this invention. It is the conceptual perspective view which showed the process which concerns on construction of the inner tank annular board (annular plate) of the LNG tank (construction) 1 which concerns on one Embodiment of this invention. It is the conceptual perspective view which showed the process which concerns on construction of the outer tank side part liner plate among the LNG tank (construction) 1 which concerns on one Embodiment of this invention, (a) is the assembly of the 1-4th stage It is the figure which concerns on construction (before roof rising), (b) is the figure which shows the thing which concerns on the assembly construction (after roof floating) of the lowest step. It is the conceptual perspective view which showed the process which concerns on construction of the inner tank roof inner peripheral part of the LNG tank (construction) 1 which concerns on one Embodiment of this invention, (a) is the outline | summary, (b) is the It is the figure which showed the roof block mounting order. It is the conceptual perspective view which showed the process which concerns on construction of the inner tank roof outer peripheral part of the LNG tank (construction) 1 which concerns on one Embodiment of this invention, (a) is the outline | summary, (b) is the roof. It is the figure which showed the block mounting order. It is the conceptual perspective view which showed the process which concerns on construction of the outer tank roof part of the LNG tank (construction) 1 which concerns on one Embodiment of this invention, (a) is the outline | summary, (b) is the roof block. It is the figure which showed the mounting order. It is the conceptual perspective view which showed the roof floating process of the LNG tank (construction) 1 which concerns on one Embodiment of this invention. It is the conceptual perspective view which showed the construction process which concerns on the 1st stage | paragraph of the inner tank side plate of the LNG tank (construction) 1 which concerns on one Embodiment of this invention. It is the conceptual perspective view which showed the inner tank roof suspension process of the LNG tank (structure) 1 which concerns on one Embodiment of this invention, (a) is the outline | summary, (b) is the detail of the suspension support. FIG. It is the conceptual perspective view which showed the process which concerns on the bottom part cold storage (center part) construction of the LNG tank (construction) 1 which concerns on one Embodiment of this invention. It is the conceptual perspective view which showed the process which concerns on construction of the inner tank bottom plate of the LNG tank (construction) 1 which concerns on one Embodiment of this invention. It is the conceptual perspective view which showed the process which concerns on construction of the cold insulation part of the LNG tank (construction) 1 which concerns on one Embodiment of this invention. It is a conceptual sectional view of an LNG tank (construction) concerning another embodiment of the present invention.

  Hereinafter, with reference to drawings, the structure concerning the LNG tank concerning one embodiment of the present invention and its construction method are explained. In the following, the range necessary for the description for achieving the object of the present invention is schematically shown, and the range necessary for the description of the relevant part of the present invention will be mainly described. According to a known technique.

  FIG. 1 is a schematic cross-sectional view of an LNG tank (construction) 1 according to an embodiment of the present invention. The LNG tank (structure) 1 preferably has a flat-bottomed cylindrical vertical tank shape with a (dome-shaped) roof excellent in earthquake resistance, but directly stores and stores LNG that requires a high level of safety. It is suitable for carrying. As shown in the figure, an LNG tank (construction) 1 according to an embodiment of the present invention is combined with a PC (PC) breakwater 10, foundation concrete 20, and breakwater 10 to form a rigid structure. An outer tub (structure) 103 formed by being inscribed in the outer shell body including the foundation slab 22 forming the housing so as to cover (directly or indirectly) the entire surface of the liquid barrier 10. And an inner tub (structure) 104 formed so as to be included in the outer tub 103, and an outer tub roof (body) 110 and an inner tub roof (joined to the top of each of the outer tub 103 and the inner tub 104 ( Body) 112, a bottom plate liner plate 201 which is laminated on the foundation slab 22 to form a bottom plate of the inner tub, a bottom cool layer 203, an inner tub bottom plate 205, and the outer tub 103 and the inner tub 104 are filled and insulated. Glass wool forming the layer 105 (board ) 105a, PUF (polyurethane foam) layer 105b, configured with perlite 105c. As an accessory, the LNG tank (construction) 1 includes a pump barrel 30, an external staircase 40, and an external hoistway 42.

The PC breakwater 10 is made of prestressed concrete. A compressive force is previously introduced into the PC steel material in a substantially vertical direction and a circumferential direction. More specifically, even if the tank achieves a large capacity of 230,000 m ³ , its own weight (inner tank, outer tank, cold insulation material, piping, equipment accessories' own weight), inner tank gas pressure, inner and outer tanks Inter-gas pressure, hydrostatic pressure, cold insulation pressure (pressure and friction force acting on the side plate of the inner tank or outer tank by the cold insulation material between the inner and outer tanks), thermal (temperature) load (acting on the inner tank due to the temperature contraction of the piping) Load), compressive force that can withstand the snow load (in heavy snow areas) can be introduced. Further, the PC breakwater 10 prevents the liquid pressure corresponding to the leakage from the inner tank even if this is a leakage corresponding to a large capacity of 230,000 m ^3, for example. The structure and construction method specified in this paper will be adopted in order to ensure liquid tightness even when acting on the dike.

  The structure of the breakwater is not limited to PC, as long as the strength equal to or higher than the above is secured, but RC (steel reinforced concrete), SRC (steel reinforced concrete), PCa (precast concrete), etc. are used. It may be.

  The outer tub 103 has a single-stage structure in which a side liner plate 103a arranged so as to be inscribed in the PC liquid barrier 10 is connected in a substantially horizontal direction so as to form a circuit in a substantially vertical direction. It is formed by stacking. The side liner plate 103a is a groove welded to each other at each stage. Welding is preferably performed by the stepping stone method or back step method for one welding rod (the same applies hereinafter).

Inner tank 104, the inner tub Annular plate 123 and the tank side plate first stage 104a-1 in which a plurality of inner tank side plate 104a is formed continuously connected in the circumferential direction on the inner tank side plate first stage 104a-1 above a tank side plate 2 stage 104a-2 formed by being articulated in the circumferential direction as the joint position shifts to the peripheral joint position of each inner tank side plate of the plurality of inner tank side plate 104a is the first stage, this The uppermost inner tub side plate uppermost step 104a-9 and the inner tub roof 112 joined to the inner tub side plate uppermost step 104a-9 via a knuckle plate 104n are sequentially configured. . In the vertical joints are welded in a circumferential joint upon articulation of the inner tank side plate 104a preferably welded after installing stiffener (not shown). The inner tank 104 is preferably made of steel containing 7% nickel. Steel containing 7% nickel is a material that has a certain level of low temperature toughness. The inventor of the present application is required to realize a large capacity LNG tank, particularly a capacity of 230,000 m3, which is the subject of the present application, while maintaining a substantial reduction in cost, a substantial reduction in construction period, and maintenance of quality such as safety. It was judged that the steel containing% nickel has sufficient accuracy as a tank plate material in the LNG tank. It is the result of comprehensively judging the improvement of the low temperature toughness in the base metal and the welded joint due to the increase in the fine retained austenite phase brought about by means of steelmaking. By using 7% nickel steel, the consumption of nickel, which is a so-called rare metal, is relatively reduced, which also contributes to the protection of the global environment. Furthermore, since such a rare metal generally tends to increase in price, the present application realizes cost reduction by relatively reducing the amount used.

  In the present application, as 7% nickel steel, it is preferable to employ Ni: 6.00% to 7.50%.

  Here, the inner tank side plate needs to realize a structure that is safe with respect to the internal pressure and the external pressure (cooling material pressure and the like). Therefore, preferably, a numerical value based on the following formula is adopted as the thickness of the inner tank side plate.

here,
t: Minimum thickness of inner tank side plate (mm)
P: The pressure (MPa) acting on the bottom of each step of the side plate is used as the hydrostatic pressure and the maximum working pressure. _Di : Inner tank inner diameter (mm)
f _t : Allowable tensile stress of material (N / mm ² )
η: Efficiency of welded joint C: Corrosion allowance (mm)
Thereby, safety is ensured.

  The heat insulating layer 105 is a layer that retains a function for suppressing the evaporation of LNG. Specifically, pearlite is used as a cold insulator around the inner tank side and the roof. The outer tub 103 holds the cold insulating material 105 and has a function of sealing nitrogen gas (not shown). The end of the outer tub roof 110 is fixed to the top of the liquid barrier 10. In the unlikely event that LNG leaks from the inner tank 104, the heat insulating layer 105 functions as a thermal resistance reducing material and introduces PUF (polyurethane foam). The heat insulating material 105 has been described by taking as an example a material having glass wool (board layer) 105a, PUF layer 105b, and pearlite 105c, but is not limited to these as long as the material has an equivalent or similar function. It is possible to adopt as what constitutes the present application without this.

  Next, the outline of the construction method of the LNG tank (construction) 1 which concerns on one Embodiment of this invention is demonstrated. FIG. 2 is a conceptual perspective view showing a process related to the construction of the inner tank side plate in the LNG tank (construction) 1 according to one embodiment of the present invention, and FIG. 3 shows one embodiment of the present invention. FIG. 4 is a conceptual perspective view showing a process related to knuckle plate mounting in the LNG tank (construction) 1, and FIG. 4 is an inner tank annular in the LNG tank (construction) 1 according to an embodiment of the present invention. It is the conceptual perspective view which showed the process which concerns on construction of a board (annular plate).

First, concrete placement of the above-mentioned liquid barrier 10 is performed (not shown). For this placement, a predetermined compressive force (as described above with a compressive force relating to strength capable of withstanding various loads corresponding to a large-capacity LNG tank such as 230,000 m ³ ) is introduced into the PC steel material in advance. The description of the construction with the foundation work, the inner tank anchor strap, etc. before and after the concrete placement is omitted.

  Next, an outer tank bottom liner plate is laid (not shown). In this construction, a heavy machine such as a tower crane is appropriately used while arranging bottom liner annular plates (not shown).

  Next, as shown in FIG. 2, the inner tank side plate 104a is constructed. In the construction, after assembling the side plate knuckle mount 50 at the lower part of the inner surface of the PC breakwater 10, the side plate 104a (104a as the ninth stage of the inner tank side plate in this figure) is used in the tank using various cranes Cl or the like. -9), and assemble using (hydraulic) crane Cl or the like. After assembling, the vertical joint is subjected to skin alignment, groove welding, and the like.

  Next, as shown in FIG. 3, the knuckle plate 104n is constructed. In this construction, the knuckle plate 104n is split at the upper end of the inner tank side plate 9th stage 104a-9, the knuckle plate 104n is taken in using various cranes Cl, etc., and the (hydraulic) crane Cl is used. Assembly, vertical joint alignment, groove welding, etc. When the knuckle plate 104n is split, it is preferable that the joint line in the inner tank side plate 9th stage 104a-9 and the joint line in the inner tank side plate 9th stage 104a-9 do not overlap.

  Next, the bottom cold insulation layer 203 (FIG. 1) is applied. This is performed by laying a wire mesh, pearlite concrete, laying a mesh lining sheet, laying a protective sheet, etc. using a bucket or the like.

  Next, an inner tank annular plate (annular plate) is constructed. As shown in FIG. 4, a frame (not shown) is installed on the pearlite block 121, the annular plate 123 is taken into the tank from the construction port (not shown) using the tower crane C2 or the like, and the forklift F or the like is installed. After using and arranging and laying on this mount, skin alignment, groove welding, etc. are performed.

  The construction of the outer tank side liner plate will be described. FIG. 5 is a conceptual perspective view showing a process related to the construction of the outer tank side liner plate in the LNG tank (construction) 1 according to one embodiment of the present invention, and FIG. It is the figure which concerns on the assembly construction (before roof rising) of an eye, and (b) is the figure which concerns on the lowermost assembly construction (after roof floating). As shown in both figures, the crawler crane CC is used to take in the side liner plate first stage 103a-1 and perform arrangement, assembly, skin alignment, groove welding, and the like. In the same manner, the assembly of the second stage (103a-2) to the fourth stage (103a-4) is performed. For these operations, the bracket scaffold BR may be used as a work scaffold as appropriate. The side liner plate first stage 103a-1 to fourth stage 103a-4 are assembled before the roof floats (described later). Regarding the assembly of the side liner plate lowermost stage 103a-L, after the roof is floated (to be described later), for example, the hoist crane HC or the like is used, and alignment, assembly, skin alignment, groove welding, and the like are performed. In addition, the assembly process of the 1st step | paragraph 103a-1 to the 4th step | paragraph 103a-4 and the assembly process of the outer tank roof (inner peripheral part) 110b can also be made into a parallel operation | work. For these operations, the gondola G can be appropriately suspended from the gondola rail GN supported from the illustrated top angle AN to provide a work scaffold.

  Next, construction of the inner periphery of the inner tank roof is performed. FIG. 6 is a conceptual perspective view showing a process related to the construction of the inner periphery of the inner tank roof in the LNG tank (construction) 1 according to one embodiment of the present invention, and (a) is an outline thereof, ( b) is a diagram showing the roof block mounting order. As shown in both of these figures, a roof mount (intermediate column) 112d and a roof mount (center column) 112e are assembled on the bottom liner plate. Then, the inner tank center ring 112a is mounted on the roof mount (center support column) 112e using a tower crane TC or the like, bolted, etc., and then the inner tank roof inner peripheral block 112b is shown in FIG. They are mounted in the order shown, are engaged with the center ring 112a and the bolts, and are appropriately subjected to skin alignment, welding, etc. using an aerial work vehicle WV or the like.

  Next, construction of the outer periphery of the inner tank roof is performed. FIG. 7 is a conceptual perspective view showing a process related to the construction of the outer periphery of the inner tank roof in the LNG tank (construction) 1 according to one embodiment of the present invention, (a) is an outline thereof, (b) ) Is a diagram showing the roof block mounting order. The blocks of the inner tub roof outer peripheral portion 112c are mounted in the order as shown in FIG. The end of the inner tub roof outer periphery 112c on the knuckle plate side is attached to the knuckle plate 104n. The center side end portion of the inner tub roof inner peripheral portion 112b is attached to the center plate 112CP. For mounting, an aerial work vehicle WV or the like is used as appropriate. After mounting is complete, skin alignment, welding, etc. are performed sequentially.

  Next, the outer tank roof is constructed. FIG. 8: is the conceptual perspective view which showed the process which concerns on construction of the outer tank roof part among the LNG tank (construction) 1 which concerns on one Embodiment of this invention, (a) is the outline | summary, (b) Is a diagram showing the roof block mounting order. The outer tub roof is mounted in the same manner as the inner tub roof, divided into an inner periphery and an outer periphery. After installing the receiving frame 110KD on the center plate 112CP and the bone receiving support 110SP on the inner tank roof 112, and using the tower crane TC or the like to mount the outer tank center ring 110a on the receiving frame 110KD, the outer tank roof The inner peripheral block 110b is mounted in the order as shown in FIG. 5B, and is engaged with the outer tank center ring 110a with bolts. In this way, the roof blocks are sequentially mounted, the blocks are joined together with a garter, and after the arrangement is completed, skin alignment, welding, and the like are sequentially performed. When the assembly of the inner peripheral portion of the roof block is completed in this way, a center plate (not shown) is mounted, and skin alignment, welding, and the like are sequentially performed. The outer tub roof outer peripheral portion 110c is also mounted in the same manner as the inner peripheral portion 110b, and sequentially performs skin matching, welding, and the like.

  Next, a roof floating process is performed. FIG. 9 is a conceptual perspective view showing a roof floating process in the LNG tank (construction) 1 according to one embodiment of the present invention. As shown in the figure, the blower BL is installed on the stage ST arranged in the vicinity of the construction port 10x. A levitation seal 110S is attached to the outer tub roof 110 to seal the gap with the side liner plate. Next, the upper wire attachment material 53 is attached to the top end of the PC liquid barrier 10, and the lower wire attachment material 52 is attached to a roof levitation anchor bolt (not shown), and the leveling wire LW is laid. After mounting other necessary levitation equipment, perform temporary levitation and final levitation. When the roof reaches a desired position, the core is confirmed, the roof plate and the top angle are aligned, and welding is performed.

  Next, the inner tank side plates 1 to 8 are constructed. FIG. 10 is a conceptual perspective view showing a construction process according to the first to eighth stages of the inner tank side plate in the LNG tank (construction) 1 according to one embodiment of the present invention. As shown in the figure, a side plate carrying cart D is installed on a stage ST arranged near the construction entrance 10x, a hoist crane HC is installed on a gondola rail GN, and a crane or the like (not shown) is placed on the side plate carrying cart D. The side plate 104a is loaded into the tank 1 and applied to the hoist crane HC. Next, the side plate 104a is moved to a desired position and assembled by the hoist crane HC, and groove welding of the vertical joint is performed. After the assembly of the side plate first stage 104a-1 is completed, the side plate second stage 104a-2 is assembled in the same manner as the first stage. After the vertical joint welding of the second side plate 104a-2 is completed, skin fitting of the peripheral joint of the first side plate 104a-1 and groove welding are performed. The vertical joint line of the first side plate 104a-1 is shifted so that the vertical joint line of the second side plate 104a-2 does not overlap. Thereafter, the process is repeated up to the eighth stage 104a-8 on the side plate.

  Next, an inner tank roof hanging process is performed. FIG. 11 is a conceptual perspective view showing an inner tank roof hanging process in an LNG tank (construction) 1 according to an embodiment of the present invention, where (a) is an outline thereof, and (b) is a suspension thereof. It is the figure which showed the detail of support. After completion of the inner tub side plate eighth stage 104a-8, the hydraulic jack JK is attached to the jack mount JKD attached before floating, and connected to the hydraulic device by piping. Thereafter, the suspension support SP attached between the roof inner and outer tubs is cut from the outer periphery toward the inner periphery and disassembled. Next, the hydraulic jack JK is operated to divide the jackdown amount into several times (J), and the inner tank roof 112 is suspended. After completion of the suspension of the inner tank roof 112, skin fitting of the peripheral joint of the side plate eighth stage 104a-8 (with the lowered knuckle plate 104n, the lower end of the side plate ninth stage 104a-9), groove welding, and the like are performed.

  Next, the bottom-part cold insulation construction in the center will be described. FIG. 12 is a conceptual perspective view showing a process related to the bottom cold insulation (center part) construction in the LNG tank (construction) 1 according to one embodiment of the present invention. As shown in the figure, after installing the cold insulation mold on the bottom liner plate, using a bucket or the like from a temporary mixer plant (not shown), placing pearlite concrete 203a into the tank central mold After drying and curing, the mesh lining 203b is laid, and the capping material 203c and the bubble glass 203d are alternately laid on the mesh lining 203b. Then, after placing ALC (lightweight cellular concrete) (not shown) on the third-layer capping material 203c, a heat-resistant board (not shown) is laid on the ALC.

  Next, the construction of the inner tank bottom plate will be described. FIG. 13 is a conceptual perspective view showing a process related to the construction of the inner tank bottom plate in the LNG tank (construction) 1 according to one embodiment of the present invention. As shown in the figure, a roller conveyor RoC is installed at the stage ST of the construction port 10x, and a slope SL is installed at the construction port 10x in the tank 1. Using a crane (not shown) or the like, the inner tank bottom plate 205 is placed on the conveyor RoC on the stage ST and pulled onto the slope SL. Thereafter, the inner tank bottom plate 205 is moved down to a predetermined position by the slope SL, and arranged along the marking Mkg. Skin alignment, groove welding, etc. are performed sequentially from the position where the arrangement is completed.

  Next, the pump barrel is suspended and installed (not shown), a predetermined inspection or the like is performed as necessary (not shown), and the cold insulation unit is installed. FIG. 14 is a conceptual perspective view showing a process related to the construction of the cold insulation portion in the LNG tank (construction) 1 according to one embodiment of the present invention. As shown in the figure, an anchor pin is attached to the outer surface of the inner tank side plate (not shown) using a long gondola (not shown) installed between the inner and outer tanks, and a glass wool blanket 105a is inserted into this anchor pin. Fix it. Next, the pearlite baking equipment PL1 is installed in the vicinity of the tank 1. Thereafter, the baked pearlite 105c is filled into the inner and outer tank side portions from the pearlite transfer rod PL2 and the outermost pearlite filling manhole PL3. At this time, the filling of the side part between the inner and outer tubs is performed substantially evenly in the circumferential direction. Close packing can be expected. When the filling of the side part between the inner and outer tanks is completed, the roof part between the inner and outer tanks is filled. At this time, filling is performed in a ring shape from the outer peripheral portion to the top portion.

  As described above in detail, according to the present invention, even when the LNG tank is enlarged, a sufficient hydraulic pressure resistance can be maintained even when a leak occurs. In addition, even if 7% nickel steel is substituted for the conventional 9% nickel steel in the inner tank, the material strength in the base material and joint can be secured without any problem in quality, and equivalent safety performance is realized. The Furthermore, the construction period can be substantially shortened even in the construction of a large LNG tank.

  The present invention is not necessarily limited to the above-described embodiments, and various alternatives, substitutions, additions, expansions, reductions, and the like are possible within the scope of equivalent technical ideas. For example, in the above description, an example in which 7% nickel steel is used as the inner tank material has been described. However, the technical idea according to the present application is not limited to this material and can be applied to those having equivalent material characteristics. It is.

  For example, an aspect in which a so-called suspension structure is adopted for the inner tank roof is also possible. For example, as shown in FIG. 15, the inner tank roof is configured such that the deck plate 60 is suspended from the outer tank roof 110 by the suspension member 50 and is covered with the upper portion of the inner tank side plate 104 a. You can also.

  In this way, the LNG tank and its construction that have been enlarged are realized while substantially reducing costs, substantially shortening the construction period, and maintaining and improving quality such as safety.

  Therefore, the present invention has great applicability in the construction industry, shipbuilding, energy industry and the like.

1 LNG tank 10 (PC) breakwater 20 foundation concrete 22 foundation slab 30 pump barrel 40 external staircase 42 external hoistway 103 outer tank (structure)
103a Side liner plate 104 Inner tank (structure)
104a tank side plate 2 stage 104a-1 1-stage within tank side plate 104a-2 within tank side plate 104n knuckle plate 105 heat-insulating layer (cold material)
105a Glass wool (board layer)
105b PUF (Polyurethane foam) layer 105c Perlite concrete 110 Outer tank roof (body)
112 Inner tank roof (body)
123 Inner Tank Annular Plate 201 Bottom Plate Liner Plate 203 Bottom Cooling Layer 205 Inner Tank Bottom Plate

Claims (6)

An outer tub in which side plates or liner plates are arranged;
A stage formed by connecting a plurality of inner tank side plates made of steel having a nickel content of 6.00% to 7.50%, which are arranged at a certain distance from the outer tank, connected in a circumferential direction. Are stacked in multiple stages so that the vertical joints, which are lines formed at the joint positions when connected in the circumferential direction, do not overlap, and in the connection in the circumferential direction, the plurality of inner tank side plates in the vertical joint In the case where the plurality of stages are laminated, the inner tank formed by welding the plurality of stages of inner tank side plates in a circumferential joint which is a line formed by the lamination;
A heat insulating layer filled with a heat insulating material between the inner tank and the outer tank;
An LNG tank comprising: a bottom liner layer in which a bottom liner plate and a bottom liner annular plate are arranged so as to fill a bottom surface of a tank defined by the outer tub and a mesh lining is laid on pearlite concrete. ,
The inner tank side plate is

here,
t: Minimum thickness of inner tank side plate (mm)
P: The pressure (MPa) acting on the bottom of each step of the side plate is set to the hydrostatic pressure and the maximum operating pressure.
D _i : Inner tank inner diameter (mm)
f _t : Allowable tensile stress of material (N / mm ² )
η: Efficiency of welded joint
C: Rotting allowance (mm)
An LNG tank having a thickness t determined on the basis of   The inner tank includes an inner tank side plate formed on a plurality of inner tank side plates connected in a circumferential direction on an inner tank annular plate, and a plurality of inner tank side plates disposed on the first stage of the inner tank side plate. Inner tank side plate 2 formed by being connected in the circumferential direction so that the position of the vertical joint which is a line formed when the plurality of inner tank side plates in the first stage of the inner tank side plate are connected in the circumferential direction is shifted. A plurality of inner tank side plates are connected in the circumferential direction so that the position of the vertical joint is displaced on the upper stage of the upper stage of the inner tank side plate, which is one stage lower than the uppermost stage of the inner tank side plate. The innermost tank side plate uppermost stage and the inner tank roof are joined to the uppermost inner tank side plate uppermost stage via a knuckle plate, and the inner tank is a welded portion in the circumferential joint and the vertical joint. The LNG tank according to claim 1, further comprising: The inner tank includes an inner tank roof and an inner tank side plate, and the outer tank includes an outer tank roof,
2. The LNG tank according to claim 1, wherein the inner tank roof is suspended from the outer tank roof by a hanging member and is placed on an upper part of the inner tank side plate.   The LNG tank according to claim 1, wherein the outer tank is made of metal.   The LNG tank according to claim 1, further comprising a liquid breakwater made of PC (prestressed concrete) in which a compressive force is preliminarily applied in a substantially vertical direction and a circumferential direction to the PC steel material. The first step of placing concrete on the breakwater;
A second step of laying the outer tank bottom liner layer;
A third step of constructing the lower part of the inner tank side plate;
A fourth step of constructing a knuckle plate on the upper end of the inner tank side plate;
A fifth step of constructing a cold insulation layer at the bottom by placing perlite concrete after laying a wire mesh;
A sixth step of constructing the outer tank side liner plate;
A seventh step of constructing the inner tank roof by attaching the end of the inner tank roof outer peripheral part to the knuckle plate;
An eighth step of constructing the outer tank roof;
A ninth step of performing a roof floating step;
It is a step of constructing the upper part of the inner tank side plate, and the inner tank side plate is connected to a plurality of inner tank side plates made of steel having an included nickel amount of 6.00% to 7.50% in the circumferential direction. A plurality of stages are stacked so that vertical joints, which are lines formed at joint positions when connected in the circumferential direction, do not overlap with each other. When the plurality of inner tank side plates are welded and laminated in a plurality of stages, the plurality of stages of inner tank side plates are welded at a circumferential joint that is a line formed by the lamination. Process,
An eleventh step of hanging down the inner tank roof;
A twelfth step of constructing the bottom cold insulation part;
An LNG tank construction method comprising: a thirteenth step of constructing an inner tank bottom plate,
The outer tank bottom liner layer is arranged so that a bottom liner plate and a bottom liner annular plate fill the tank bottom defined by the outer tank, and a mesh lining is laid on the pearlite concrete,
In method of constructing LNG tanks, characterized in that the inner tub roof is lowered suspended after the the first 11 the inner tub roof and the outer tub roof in the process of being floated is temporary connected by bone receiving support member There,
The inner tank side plate is

here,
t: Minimum thickness of inner tank side plate (mm)
P: The pressure (MPa) acting on the bottom of each step of the side plate is set to the hydrostatic pressure and the maximum operating pressure.
D _i : Inner tank inner diameter (mm)
f _t : Allowable tensile stress of material (N / mm ² )
η: Efficiency of welded joint
C: Rotting allowance (mm)
The construction method of the LNG tank characterized by having thickness t determined based on this .

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