KR100835623B1 - Containment system for compressed fluid - Google Patents

Abstract

The present invention relates to a gas storage and transportation system for a vessel formed of small diameter steel pipes wound and stacked in a special way. The system is suitable for use on the top of a barge or inside a cargo compartment of a ship when stored in a secondary containment system. Various types of stacking and winding pipes are disclosed. Special materials for making pipes are also disclosed.

Pipe, loop, containment structure, containment system, circular helix, square helix, nickel, carbon fiber, support matrix

Description

Containment System for Compressed Fluids {CONTAINMENT SYSTEM FOR COMPRESSED FLUID}

The present invention relates in particular to a containment system for compressed fluids for marine transport and storage of compressed natural gas.

The invention relates in particular to the marine gas transport of compressed gas. Many designs were uneconomical because of the high costs involved in the complexity of existing offshore gas transportation systems. The structure described herein is an improvement on the structure disclosed in US Pat. No. 5,839,383, issued November 24, 1998.

It is therefore an object of the present invention to provide a storage system for compressed gas which can hold a large amount of compressed gas, can simplify the system of complex manifolds and valves, and can also reduce manufacturing costs.

Multiple designs of containment structures are disclosed in which a plurality of loops of a wound pipe are formed of a plurality of layers including at least a first layer and a second layer. The pipes form the connections between the layers. In one embodiment, the wound pipe of the first layer is wound in a different way than the wound pipe of the second layer. In another embodiment, the wound pipe of at least one of the layers is formed from portions with different radii of curvature. In another embodiment, the wound pipe of at least one of the layers is formed with portions forming a superimposed complete circle. In another embodiment, the wound pipe of at least one of the layers is formed from portions having different centers of curvature. In another embodiment, the connection pipes form a connection between the non-adjacent layers. In another embodiment, the pipe has a support matrix formed of a mixture of different fluids surrounding the layer of pipes. In another embodiment, the support matrix comprises a fluid having a specific gravity greater than one. In another embodiment, the support matrix is formed of a plastic material that mates with the pipe. In another embodiment, the pipes form a pyramid shape. In another embodiment, the pipe is a carbon fiber pipe. Various embodiments are formed of any viable combination of these features.

In another aspect of the present invention, there is provided a containment structure comprising at least a first layer and a continuous wound pipe formed in a second layer overlying the first layer, wherein the wound pipe of the first layer is raised to With the exception of the first transition zone, which forms part of the second layer and crosses the wound pipe of the first layer, the wound pipe of the second layer lies directly on top of the first layer and is aligned with the wound pipe of the first layer. It is preferable.

In yet another aspect of the present invention, a method is provided for forming a containment structure comprising at least a first layer and a continuous wound pipe formed in a second layer overlying the first layer. Forming a continuous wound pipe and forming a second layer overlying the first layer. And further comprising forming the third layer by raising the wound pipe of the second layer to initiate the third layer. The wound pipe of the second layer is laid directly on top of the first layer, except for the first transition zone where the wound pipe of the first layer rises to form a portion of the second layer and intersects the wound pipe of the first layer. Aligned with the wound pipe of the first layer.

In still another aspect of the present invention, there is provided a containment structure comprising a continuous constant diameter wound pipe formed in a single layer of alternating constant radius circle portions, where each continuous where n is greater than one. Each circle part covers 360 / n degrees, with the circle part being larger in radius by 1 / n pipe diameter than the preceding circle part.

The containment structure of the present invention is particularly suitable for use as a gas storage system and is particularly suitable for ships (in cargo ships of ships, or in secondary containers) or simple barges (inside or above deck of barges, or in secondary containers). It is suitable for transporting an amount of compressed gas. The wound pipe is preferably formed of a long, mainly circularly curved portion of a small diameter steel pipe. In general, pipes smaller than 8 inches can be wound in a special way within a simple round container.

In one embodiment, the diameter of the container is about 50 feet and has a height of about 10 feet. The container also has an inner wall and an outer wall, and the inner wall is cascaded. Approximately 10 miles or more of pipe may be wrapped and stacked in a container. The coil winding is continuous and there is no valve or disconnection from the beginning to the end of the coil.

In one aspect of the invention, the pipe may appear to start inside the bottom layer. The pipe is spiraled outwardly by a constant radius portion of a constant curvature, preferably by a semi-circle in which the center and radius of the curvature change by a small percentage of the curvature and the overall curvature, respectively. In this way the programming and quality control of the bending rollers are kept constant and simple for a relatively long time. When the pipe reaches the outside of the container, it is raised to the second layer by the container's geometry and an inward spiral begins. After the two half-circles there is a transition curve that runs directly below the two pipes at a distance of about 12 pipes. The distance is relatively short so that the vertical stacking stress at the intersection is minimized. The net inwards spiral gain of one pipe is achieved by transitioning down two pipes and then spiraling one of the pipes backward, just above the first and subsequent odd layers. As a result, the odd layer helix faces outward and the even layer helix points inward. In an even layer, when the pipe reaches the interior of the circular container, the even layer rises above the odd layer and the geometry of the projection becomes the same as that of the first layer. As a result, the odd layer consists entirely of semicircles, and the even layer consists of semicircles with very short transition zones.

The present invention includes a containment structure made by layered wound pipes directly over one another except for the transition zone and a method of winding the pipe to obtain this containment structure.

According to the gas storage system of the present invention, firstly, the pipe is small and the risk of damage is greatly reduced. The likelihood of damage is also reduced. Secondly, the cost for the production of long straight sections and subsequent constant curved pipes becomes low. Thirdly, the system can be checked continuously by internal pigs. Fourth, there is no complicated curved shape for about 97% of the wound length. Fifth, the wound layout and the vertical stacking arrangement reduce the load stress. All of these features greatly reduce costs.

Corresponding similar parts to all the different drawings will be described below with reference to the drawings in which like reference numerals designate the same. It can be seen that the materials used to make the pipes and their connections are flexible and do not break well at the suggested operating temperatures. Pipes and their connections can be made of generally grade steel X70. As used herein, the term "comprising" is used in a comprehensive sense and does not mean that other features are excluded. In the present specification, even an element expressed in the singular form does not exclude a case in which the element is plural. The radius of the wound pipe generally indicates the radius of the coil. The cross-sectional diameter of the pipe represents the diameter of the pipe. Continuous wound pipes are made by welding the pipes together so that the pipes are continuous.

1-4 illustrate specific embodiments that implement some aspects of the invention. 1 and 1B show in detail a plan view of a portion of two bottom layers of a generally circular continuous small pipe. Subsequently lying on these bottom layers another pipe layer and the projection line in the figure leads to the first layer shown in solid lines if the layer is an odd layer and to the transition zone shown in dashed lines and solid lines if the layer is an even layer. Except for the transition zone, which will be described below, the wound pipes of the subsequent layers are placed and aligned directly on the wound pipes of the preceding layers. Thus, there is a straight contact area between successive layers of pipe that distributes the weight of the pipe in an optimal manner.

The first layer 10 starts with a small pipe with an inner radius Rmin 12 to form a semicircle. The center of curvature changes sharply by 1/2 pipe and the radius increases by 1/2 pipe. This causes the inside of the pipe to be exactly tangent to the outside of the starting point of the pipe helix as indicated by reference numeral 16. Thus, the path of the pipe travels by one pipe diameter in a range of 360 degrees by the use of two specific semicircles. This simplifies the complexity of the input to the bending roller giving a defined bending curvature to two constant values. The bottom layer continues outward in the same way as the semicircle continues to increase. When the pipe reaches the outside of the container 18, the pipe rises and lies just above the outside of one layer 20 and continues to wind in two layers until the start point of the transition zone 22 is reached. Then, as shown in Figs. 2, 3 and 5, the paths indicated by the prescribed mathematical formulas are connected in such a way that they are directly above the lower pipe, leaving the pipe directly below in a horizontal contact manner. However, in the transition zone it is directed inwards by two pipe diameters.

This transition, denoted A B C, takes place within a distance of about 12 pipe diameters and accommodates cross point support at point B.

This short transition length means that only 3% of the coiling has a continuously varying curvature. Arrow “26” is in some way moved inward by two pipe diameters and even layer is placed directly on top of the outward helix by about 94% of the total coiling so that the even layer is pure inward helix even if aligned with the outward helix. It indicates if it moves outward again by two pipe diameters. Described below is a summary of the content associated with FIG. 1:

The odd layer helix faces outward and the even layer helix faces inward.

The odd layer does not have a transition zone.

The even layer has a transition zone equal to about 12 pipe diameters.

Approximately 97% of the wound uses pure circular curvature.

The outside of the transition zone (ie the part not the transition zone) represents about 94% of the total coiling, and all the pipes in each layer (about 40 or more layers) lie directly on top of each other.

For the whole coiling system, inside and outside the transition zone, the radius of curvature is greater than about 11 diameters. This configuration applies where the layer changes from one to the other. Therefore the maximum bending strain does not exceed the limit of about 5% which is constantly defined.

Inside and outside, where the lower layer rises to the higher layer, the transition equation (see FIG. 5) is also used. However, it is combined with two short reverse arcs connected by straight sections in a vertical plane that accommodate upward and lateral transitions.

Outside the rising layers become odd to even and the rising layers inside become even to odd.

Every 180 degrees in an odd layer, the radius of curvature changes abruptly by an amount corresponding to the half-pipe diameter. In addition, the center of curvature changes by the same amount, resulting in a full radial transition of the diameter of one pipe beyond 360 degrees.

The criteria for even and odd layers can be changed by inserting transition zones in the bottom layer, but the disadvantage is that the bottom layer has a higher stress at the bottom intersection point than the intersection is in the second layer.

2 is an enlarged view of the outer part of the transition zone. The basic transition general equation 28 is cited and the mechanism of the solution is represented in FIG. 5. Also described in FIG. 2 is a simple function 32 which depicts the pure semicircle making up 97% of the coiling structure. Section points A B C are marked and these points can be tracked later in FIG. 4 to complete the three-dimensional picture. 2 also shows the outer wall 18 of the container and the accompanying transition properties.

3 is an enlarged view of the inner portion of the transition zone. The cross-sectional position D E F G is indicated and shown in FIG. 4. The transition general equation 28 is exactly the same as in FIG. 2, but the specific values of the constants are numerically different. This numerical difference results in a transition curve with no reverse curvature, such as with an outer transition curve.

4A-4G show the bottom four or five layers inside and outside the coil container vessel. For example, tracing pipe number 6 first shows the paths A B C and D E F G shown in the three figures. Tracking pipe number 4 of sections A, B and C shows how the first layer changes to the second layer. This shows why only the odd layers rise from the outside. Similarly, it can be seen why only even layers rise inside.

A more detailed description of FIGS. 4A-4G is described below. The starting point of the pipe coil can be seen in section F of the pipe with the number 1 in the center. Directly above section G represents pipe number 1 and this part of the pipe is located close after section F. The next part of the located pipe can be seen in section D, with the number 2 marked in the center. The part after the next part is in section E and the center is marked with the number 2. Thus, the way in which the chain of pipes is located at the beginning of the floor or first floor is Fl (section F, meaning pipe number 1), Gl, D2, E2, F2, G2, D3, E3, F3, G3, D4, It may be described as E4, F4, G4. This procedure continues outward at the same time by one pipe diameter until the position Al of section A is reached. The final order of placement for the first layer may be described as Al, Bl, C1, A2, B2, C2, A3, B3, C3, and A4. Thus this describes the arrangement of the first layer which is wound outward. The pipe then rises and begins to move inward at the second floor. The order is given by B4, C4, A5, B5, C5, A6, B6, C6, A7, B7, C7, A8, B8, and C8. This procedure continues inward by one pipe diameter at the same time until position D5 of section D is reached. The final order of arrangement for the second layer can be described as D5, E5, F5, G5, D6, E6, F6, G6. The pipe then begins to ascend at D7, reaching the third layer at E7, with the result that the outward movement sequence is F7, G7, D8, E8, F8, G8, D9, E9, F9, G9. The rest of the coiling is in sequence A9, B9, C9, A10, B10, C10, All, Bll, Cll, A12, B12, C12, A13, B13, C13, A14, B14, C14, A15, B15, C15, A16, B16, C16, .... D10, E10, F10, G10, Dll, Ell, Fll, Gll, D12, E12, F12 and G12 continue outward and inward in a similar manner. First only five layers are shown in FIGS. 4A-4G. The pattern is repeated for as many layers as needed, usually 20 or 30 layers.

Figure 5 shows a simple program, expressed in basic language, which first shows the geometry represented by three numbers. The print function is graphical but the output can be easily represented in a numerical coordinate system. The main feature 30 of the program between lines 190 and 400 mathematically describes how the constants for the transition equations are solved. This solution is essentially a variation of the standard Gaussian equivalent. The actual general equation 28 is unique for this coiling process. Also, the exponent used in the equation (D in line 240) is unique in that it can be used as a rotational parameter that provides nearly complete nesting of the pipes of the transition zone.

Thus, it can be seen that this embodiment of the present invention provides a special coiling method or system for small diameter pipes with a long continuous length of small diameter pipes (approximately 5 to 8 inches in diameter) of approximately 10 miles. About 97% of the pipes are curved with a constant curvature over an interval of approximately 180 degrees arcs (the simplicity of such a constant curvature greatly reduces manufacturing costs). The only transition method (for about 3% of the coil length) may allow about 94% of the pipes to be placed directly on top or bottom of other pipes. Such stacking patterns greatly reduce local bending and cross point stresses, and as a result, reduce the overall wall thickness of the pipe or increase the acceptable stacking height of each container. It can be seen that this embodiment also provides a method of coiling pipes which continuously outwards and outwards the spiral by the use of a stepped constant curvature for about 97% of the total length and a mathematical method describing a special coiling structure. .

The coil is shown as a semi-circle of constant radius, but where n is greater than 1, it may be a part of 360 / n degrees where the diameter of each part increases by 1 / n pipe diameter, but each of n / 2 The amount of increase is undesirable because it increases the number of pipe bend control points. In the containment structure made by this method, for each k-th part except the part that forms the outer boundary of the containment structure, the k-th part wound pipe abuts the k + n-th part wound pipe, Form a gapless structure. Although the example is shown that the transition zone occupies 12 pipe diameters, it is contemplated that the above advantages of the present invention can still be achieved if the transition zone occupies less than 50 pipe diameters.

The wound pipe typically forms a containment structure having valves at both ends of the pipe. The wound pipe is suitable for storing gas. The wound pipe is preferably enclosed in a container 18, which is sealed to provide a secondary containment structure and preferably equipped with leak detection equipment.

Starting with various coil stacks composed of a plurality of flat spirals, another embodiment of the present invention is described below.

5A and 5B show spirals with continuously varying curvatures. For convenience of terminology, FIG. 5A shows a left helix and FIG. 5B shows a right helix. The right or left helix is determined by keeping the thumb up and checking whether the finger follows the pipe in the direction of departure. FIG. 5B is obtained from FIG. 5A by inverting FIG. 5A, that is, by rotating it 180 degrees about the axis of the plane of the coil.

6A and 6B illustrate multi-circular spirals. Figure 6a shows a two-center multi-circular helix made up by two centers on a vertical axis separated by D / 2 where D is the diameter of the pipe. The arc is drawn 180 degrees at the radius R from the center, the subsequent arc is drawn at 180 degrees with the radius R + D / 2 from the center, and the subsequent arc is 180 degrees at the radius R + D from the center. The arcs are drawn in the same way as they are. FIG. 6B shows a four-center created by four centers spaced by D / 4, where an arc of constant radius is 90 degrees long and the radius increases by D / 4 between adjacent arcs. Many other multi-circle helices are possible. A concern in this variant is the feasibility of the fact that the winding machine is too difficult to accurately produce a continuously varying curvature.

7A shows a stepped circular helix. In this spiral, the pipes are superimposed in the form of a full circle, with the radius increasing by D, except for a small transition zone comprising an S-bend consisting of a positive arc and a negative arc whose radius is the minimum bending radius. have. These arcs are positioned such that there is no change in curvature at the point of movement between the arcs or between the arc and the circle. The transition zone changes the series of outward spirals (clockwise). The transition zone can be stepped outward as well as stepped inward as shown in FIG. 7B. The basic helix here is a two-centered outward multi-circular helix. The transition zone creates a double inward step, creating an effective inward extension. FIG. 7C changes the outward helix into an inward helix by forming the same two-center outward multi-circular helix and forming two single inward steps per revolution. While there are two transition zones, these two transition zones have the advantage of being shorter than each double transition zone.

8A is an example of a rectangular coil, which in this example is a square coil. The corners are all the same 90 degree part of the pipe with a small radius of curvature, for example a minimum bending radius. These corners are connected by straight portions of the pipe of increasing length such that the outer loop of the pipe spirally surrounds the inner loop of the pipe. Such a spiral can be made by welding a straight portion to the corner portion. In this case, the corner portion is a short pipe that can be bent with a rotary die bender using a main shaft that allows the pipe to be bent tightly rather than elliptical. The lengths of the two pipe parts are not equal and increase by one half of the pipe diameter over the preceding parts. This is an example of a four-center, square helix, schematically shown in FIG. 8C. 8B shows a two-center square helix that is easy to manufacture, with the length of half of the straight pipe portion equal to the length of the preceding pipe portion. If the part of all the pipes on the two parallel sides of the square is increased in length by a certain increment, the shape produced becomes a rectangular helix. If the long side of the rectangle is considerably long, the number of welded corner portions for the total volume of the coil is reduced, thereby increasing the economy. At the same time the radius of the corner portion can be reduced, for example to 2D, in that the lost space inside the coil is reduced. As a combinatorial effect, low cost coils can be produced which fill a rectangular space.

The method of overlapping connection to the horizontal pair of spirals described in the previous section is described below. For practical use, the coil stack requires many layers, for example 20 layers. However, since only one layer interacts with the top or bottom layer, the following discussion of two adjacent layers and how they can be paired are limited.

9A shows that the second helix is located directly on top of the first helix. The result should be a complete cuboidal packing, but as long as the pipe ends are facing in the same direction adjacent to each other, there will be a deviation from the complete cubic packing at the connection. The connection fitting can be a simple loop.

9B shows an embodiment in which the second helix is rotated 180 degrees in the plane before overlap. The two layers fit together with a full hexagonal packing. The inner ends can be connected together by welding the S-bend fittings, and because the fittings are short, they can be tightly curved using the main shaft if necessary. For circular and rectangular spirals, this shape is considered to be advantageous where the pancake shaped spiral winding has no significantly lower efficiency than the continuous winding of the coil stack in the continuous pipe.

FIG. 9C is a design similar to that of FIG. 9B except that the second layer is longer by half a turn so that two outer ends are raised on the same side of the coil. Such a configuration may be useful if it is beneficial to have all inner-layer connection fittings (“releases”) located on the same side of the coil stack, eg, rectangular stack.

In FIG. 9D, the second helix is turned upside down. In other words, it is rotated 180 degrees about the plane's axis before overlapping. The "inlet / outlet" shape can be made by winding the pipe continuously in one direction. To allow different levels, the ends are opposed to each other and can be easily connected. The joint may be by S-bend fitting, or in the case of continuous windings, the pipe is bent into S-bend shape in vertical size. However, there is a serious problem of pipe support because the stacking of the two layers is neither a cube nor a hexagon. Only the pipe on the second layer intersects the pipe of the first layer at a point 180 degrees apart, with substantially no support therebetween. This is an unacceptable situation that can be solved by the use of stepped spirals as discussed below.

In FIG. 9E, two identical circular stepped spirals are shown with the second helix turned upside down. This is the spiral of FIG. 7A. Since most of this helix's rotation is a full circle, the pipe will lay directly on the pipe of the first helix to form a cubic packing when the second helix is turned upside down. Only the transition zone does not have a cubic packing, but the transition zone is short and does not have the serious problem of unsupported pipes. Since the second helix is inverted, the inlet / outlet shape and the pair above can be changed from one helix to the adjacent helix by a three-dimensional sigmoidal bend at the outer and inner ends. Can be made into continuous pipes.

In FIG. 9F, the first helix is from FIGS. 5A, 6A or 6B and the overlapping helix is a double inward stepped helix of the type shown in FIG. 7B, the latter basic helix having the same identity as the first helix. Referring to FIG. 9F, the situation is very similar to that of FIG. 9E except that the second helix is not upside down. Except for the transition zone, it is the same helix as the lower one, forming a cubic packing. The double intersection points convert the outward helix into an inward helix, so that the ends are easily connected by three-dimensional small sigmoidal bends into two adjacent helices, as shown in FIG. 9E. This combination of layers can thus be wound from the continuous pipe by a suitable machine.

In FIG. 10A, the first helix is a rectangle with two or four centers and the overlapping helix is the same but rotated 180 degrees in its plane. It is very similar to the situation in FIG. 9B except that the circular helix is replaced by a rectangular helix, resulting in a hexagonal packing. Since both helices are outward, they must be connected internally by large S-bend fittings in which one pipe diameter rises to the third dimension. The outer end of the bilayer is on the opposite side.

In FIG. 10B, the same situation as in FIG. 10A is shown, except that one of the layers is extended by two additional segments, 180 °, so that both outer ends are visible in the same plane. This may be useful to enhance the packing of adjacent rectangles or squares or to arrange that all outer pipe connections appear at the end of a rectangle, which may be suitable for a barge, for example.

The stacks of spiral pairs and their connections are now described. Previously, how the helices identified in FIGS. 5A, 5B, 6A, 6B, 7A, 7B, 7C, 8A, 8B and 8C meet the stack specification, for example primarily cubic packing or hexagonal packing, in pairs. Considered whether it can be combined. Because of the symmetry of the flat helix from one side to the other, if helix B fits on top of helix A with hexagonal packing, helix A also fits on top of helix B with hexagonal packing. Continuing in this way, many identical pairs of stacks with hexagonal packings will have hexagonal packing as a whole.

Of course, the same pair of stacks represents a columnar arrangement in the vertical direction. However, the top layer does not have to have the same degree of rotation as the bottom layer. If each layer has one less rotation than the layer just below it, the stack is angled inward from 30 degrees from vertical for the hexagonal stack or 45 degrees from vertical for the cube. The result is a pyramid. Pyramid stacks have less demand for their containment structure than columnar structures, which can be advantageous in many situations.

Of the spiral pairs discussed above, the designs (stepped circles) of FIGS. 9E and 9F have the properties of a cubic packing (except transition zones). They also have the property that adjacent layers are wound spirals in opposite directions. This in turn means that the pipe at the end of one helix faces in the opposite direction to the pipe at the start of the other screw, which means that it can be easily connected by an S-bend rising from one layer to another. . This also means that if the continuous winding process can make the S-bend in three dimensions, they can be made in the continuous winding process. Otherwise, the S-bend is a fitting to be welded. These S-bends are required on the inside and outside of the helix. This situation is illustrated in Figures 11A and 11B.

Of the spiral pairs discussed above, FIGS. 9B and 9C (circles) and 10A and 10B (rectangular) have hexagonal packings. They have this property because both helices are wound in the same direction, meaning that the pipe at the end of one helix faces the same direction as the pipe at the end of the adjacent helix. Connecting one to the other requires a loop of pipe that rotates 180 degrees. A simple loop can be used to connect adjacent pipes. If the criterion of minimum bending radius is observed, these loops may become coarse and may not stack well with respect to the vertical plane of the stack. However, if there is no space in the direction away from the stack, this may be the case with a cubic-packed circular stack, which may be essentially coplanar with the helix and the stick from its face. This is illustrated in FIG. 9B, where the loop is connected to all the second layers on one side of the stack with the same loop on the other side of the stack, and the loop is connected to the adjacent layer in the design of FIG. 9C. It is. These adjacent or next adjacent horizontally connected loops may be desirable in situations where there is interest in pooling liquids that are liquid in the pipe and that are low spots in the structure, since this style of loop does not provide a point for pooling. to be.

In many other cases, especially with rectangular helices, tight packing of the stack is important, and it is undesirable to have loops that protrude out of the stack. Loops of adjacent layers can be wound vertically and pressed against the stack to improve packing, but a better solution is obtained by not trying to connect adjacent layers. This case is schematically illustrated in FIG. 12A, where loops of minimum bending radius taking approximately 3D are used to connect pipe ends spaced at least six pipe diameters in the vertical direction. These loops ("ears") are in a vertical plane parallel to the vertical wall of the stack, where the vertical plane is disposed outside of the stack by one pipe diameter, so that all loops are looped by one pipe diameter. You must start the S-bend in the spiral plane moving outward. In this example there are twelve pairs in the design form of FIGS. 9B and 10A stacked on twelve pipe ends on each side. This schematic shows how they can be connected by ears on two sides to provide one continuous pipe path through all 24 spirals. Here, for 10 pipe diameters, only one pipe diameter was lost on each side. If the pairs take the form of FIGS. 9C and 10B to replace half of the ears appearing in the other side of the stack, both sets of ears may appear adjacent to each other on the same side of the stack. This will be attractive when close packing is important. For example, if both sets of ears are on a rectangular stack on one side, only one extra pipe diameter is added to the length of the track to provide this connection.

The combination of the FIG. 10B form, ie a rectangular stack with a pair of hexagonal packings, and the close fitting ears as described above provides the highest pipe density of all designs described herein assuming that the space to be filled is essentially rectangular.

U.S. Patent 5,839,383 discloses a rigid structure designed to support the stack of Figures 11A and 11B described above. With appropriate modifications, similar rigid structures may be used to support the other types of stacks described above.

This patent also proposes the use of a matrix to fill the spaces between the pipes as a means of reducing the tendency of ellipsation to provide support to the pipes to promote fatigue stress. One type of matrix proposed is water whose specific gravity is adjusted by another additive to bring it closer to the specific gravity of the pipe. What was not explained was the idea that the matrix must have high calories in order to reduce temperature fluctuations in the walls of the pipes during loading and unloading and otherwise to increase the thermal mass of the inclusion as a whole. Significant improvements in thermal properties are achieved by using a mixture of water and one of the common glycols for high density (specific gravity 1.1) and high temperature (freezing point near -40 degrees Fahrenheit), and low density (specific gravity 0.9). If the temperature is low (-40 to -80 degrees Celsius) it will be obtained by using a mixture of water and methanol. Water is attractive because it has a high specific heat and a high melting point.

Basically, the desirable properties for solid matrices are low cost, low density, and the ability to fit close to the pipe to provide maximum support. This is true if the temperature can be elevated by, for example, steam passing through the pipe so that the plastic matrix can soften and conform to the pipe after the coil stack has been completed with an appropriate amount of plastic between the layers. It suggests the use of low cost plastics such as mixed plastic scrap. Similarly, products with similar properties that can be considered are pitches extracted from oxidized or unoxidized coal or petroleum (black residue left after distilling crude oil, coal tar, etc.). The effective viscosity of these matrices must be very high at room temperature and must be solid for all practical purposes. This viscosity can be increased by addition of fibrous material, if necessary. It may be unfamiliar to support steel pipes with such products, but they are used purely for compression, and the pressure is not very high, for example 10 to 20 psi at most.

The need for matrix support becomes more important for the transition to higher strength materials for pipe structures, as described in the next section, which changes the resistance of the pipe to ellipsation as a third force of wall thickness. This facilitates the transition of thinner wall walls to pipes.

One of the most important factors in the commercial value of transporting natural gas in compressed form is its density. There are two basic ways to increase the density of gases: increasing the pressure and decreasing the temperature. In the case of CNG transportation, the cost of the pressure containment system is very important. The transition from low cost conventional line pipes to low nickel, low temperature steel as disclosed in the PCT / US98 / 12726 application is delayed by high forced cost per ton. The same is true of carbon fiber composite continuous pipes of the same pressure rate as composite pipes, especially line pipes. Because of the thumb law, carbon fiber pipes cost 1 1/2 times more than ordinary steel pipes for the same pressure ratio. Low nickel herein means about 1 to 5 weight percent.

At room temperature between 30 and 50 degrees Fahrenheit, there is a significant difference in gas density between low pressures such as 1000 to 1500 psi and high pressures such as 3000 to 4000 psi. But when the temperature approaches 20 degrees Fahrenheit, the critical point of the gas, the difference is significantly reduced. As a result, it is possible to obtain gas densities at 1000 psi which are equal to or higher than at room temperature of 3000 psi. In this pressure range, carbon fiber pipes will cost half as much per foot as conventional line pipes. With half the cost of pipes, you can use twice as many pipes as line pipes and carry twice as much tonnes of gas. With the cost of the ship and the cost of approximately the same pipe and twice as much cargo, the savings are greater than the deduction of the added refrigeration cost subtracted by itself by the reduced compression cost.

Thus we have the surprising result that the economics of shipping can be improved by the shift to more expensive containment materials.

When the temperature falls within the range of the critical point, the gas is called a "high density phase" gas. Below the critical temperature, the gas is called liquid gas, and there is no point where the properties of the gas change drastically. Within the phase envelope below the critical pressure over the temperature range, the compressed gas is with such a liquid phase. These various forms of gas can be regulated by the containment system and all forms are referred to as "compressive fluids" for the purposes of this patent document.

The constituent material of the pipe may be:

1. Common API line pipe steel.

2. Quenching and tempering steel.

3. Low temperature high tensile strength steel which can be quenched and tempered and nickel content is below 3%.

4. Steel pipes wound with high-strength reinforced fiber, such as carbon fiber or high-strength steel wire, essentially only in the direction of the hoop. This is a way to double the pressure capacity of the pipes while minimizing the cost and weight increase.

5. A composite pipe consisting of a spiral winding of high tension fibers embedded in a matrix around a relatively low strength core pipe ideally having low permeability to methane.

6. While the materials are advantageous, other materials are also possible, such as extruded aluminum, directional extruded polyolefins, ceramic fiber reinforced metals.

Considerations for coil stack configurations include the following:

1. Ease and speed of manufacture eg continuous winding, efficient testing.

2. Ease of Repair: When stacked, it is advantageous to allow the coil of horizontal pancakes to divert leaking pancakes around.

3. inspection ability; For steel pipes that are exposed to corrosion, this essentially means that it must be possible to pass the intelligent pig through the entire coil, which means a corner part of a constant internal diameter and the radius of the pig, for example larger than 2D.

4. Operational Considerations: If a significant amount of liquid produced is formed, there should be no low point where pooling may occur, and if fluid extrusion is employed, the pipe diameter minimizes over-riding or under-riding of the fluid. It should be small enough to

5. Space filling: In general, the maximum density of the pipe is advantageous to take into account the useful space to be filled, which is generally advantageous with rectangular coils and flanged away from the inside of the coil.

6. Safety: To avoid fatigue cracking, the elliptical shape of the pipe is required to be kept to a minimum, which means that the roll bending pipe must be of a certain minimum radius, and to minimize the effect of cracking caused by any factor, The pipe diameter should be of a suitable size so that the flow rate of gas through the cracks is suppressed by a suitable pipe diameter.

The invention has been described with reference to the preferred embodiments and the substitutions and other changes of parts will be apparent to those skilled in the art. Changes from the illustrated are intended to be within the scope of the present invention.

Preferred embodiments of the present invention are described with reference to the drawings, which are for illustrative purposes only and are not intended to limit the technical scope of the present invention, wherein like reference numerals denote like elements.

1 is a plan view of a layer of pipes;

1A is a cross-sectional view taken along the line AA ′ of FIG. 1;

1B is a detailed view of FIG. 1;

2 is an enlarged plan view of the outer transition portion of FIG. 1;

3 is an enlarged plan view of the inner transition portion of FIG. 1;

4A, 4B, 4C, 4D, 4E, 4F and 4G are a series of cross-sectional views of the portions shown in FIGS. 2 and 3;

5 is a computer program used to accurately define the geometry, lines and coordinates of FIG. Lb; More specifically, a copy of the mathematical conversion mechanism used to define the transition curve;

5A and 5B show the right and left spirals of continuously changing curvatures;

6A and 6B are cross-sectional views of pipes with portions of increasing radii of curvature forming multi-circular spirals;

7a shows a pipe with a stepped circular helix;

FIG. 7B shows a double inward staircase on two centered outward multi-circular spirals; FIG.

FIG. 7C shows a pipe with two single inward steps per revolution on two centered outward multi-circular spirals; FIG.

8a shows a layer of pipe formed of four centered square spirals;

8B shows a layer of pipe formed from two centered square spirals;

8c shows a layer of pipe formed of four centered square spirals;

9A shows a direct overlap of two helices;

FIG. 9B illustrates the overlap of two circular spirals with one spiral rotated 180 degrees with respect to the other spiral; FIG.

FIG. 9C shows a state in which one end of two identical spirals has a length corresponding to half rotation, so that both ends stand up on the same side of the coil for easy connection, and show pipe connections connecting adjacent layers. FIG. drawing;

FIG. 9D shows a state in which the second helix is flipped around one axis in the plane of the helix; FIG.

9E shows a pure circular helix following FIG. 7A;

10A shows a rectangular pipe layer with pipe connections between inner helices;

10B is a top view of a rectangular pipe layer with two rectangular spirals superimposed in a 180 degree rotation;

11A shows a sigmoidal bend portion connecting adjacent layers;

FIG. 11B shows sigmoidal bends between adjacent layers outside the stack; FIG.

FIG. 12 shows a state in which the stack of spiral pairs shown in FIGS. 9B and 9C and 10A and 10B can be connected to make one pipe;

12a shows a pyramidal pipe structure by continuous layers with reduced widths; And

13 is a T-P graph for methane.

Claims (14)

A containment system for compressed fluids comprising a plurality of pairs of flat spirals, wherein the pair of layers are centrally connected to each other by S-bends and the outer ends of the plurality of pairs of flat spirals to form one continuous pipe The containment system for compressed fluid, characterized in that is connected to adjacent pairs by a 180 degree loop in the plane of the helix. 2. The containment system of claim 1, wherein each pair of outer ends is connected to the other by a vertical 180 degree loop in such a way that all the pipes in the stack are connected by one continuous pipe. 3. The containment system of claim 2, wherein the outer ends are connected such that all pipes in the stack are connected by at least two continuous pipes. 4. The containment system of any one of claims 1 to 3, wherein the number of revolutions decreases by one as each layer in the stack rises, resulting in a pyramid of the stack. 4. A pipe according to any one of the preceding claims, wherein the pipe is supported by a liquid support matrix comprising additives such as glycol or methanol selected to have a suitable density and suitable temperature range where water and water crystals are formed. A containment system for pressurized fluids. The polyolefin or scrap according to any one of claims 1 to 3, which has a high viscosity in a nearly solid state but low softening temperature at room temperature so that the pipe can be heated to a temperature at which the matrix is formed into a pipe. A containment system for compressed fluid, characterized in that the pipe is supported by a solid matrix comprising plastic or coal pitch or oxidized petroleum pitch. 4. A containment system according to any one of claims 1 to 3, wherein the pipe component material is at least moderate strength line pipe steel. 8. The containment system of claim 7, wherein the strength of the steel is obtained by quenching and tempering. 9. The containment system of claim 8, wherein the pipe component material is at least moderate strength low nickel, low temperature steel. 9. The containment system of claim 8, wherein the pipe component material is a synthetic pipe reinforced with glass and / or carbon fiber. 11. The containment system of claim 9 or 10, wherein the pressure of the compressed fluid is reduced to near the critical temperature to reduce the pipe pressure rate such that the compressed fluid is a high density phase where the pressure is significantly reduced. delete 4. The containment system of any one of claims 1 to 3, wherein the compressed gas is natural gas. 4. The containment system of any of claims 1 to 3, wherein the pipe is made of steel containing nickel in the range of 1 to 5% by weight.

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