KR20140115311A - Optimised vessel - Google Patents

Abstract

The pressure vessel for containing the CNG includes a cylindrical body closed between two end dome. The cylindrical body and the dome define the convex volume and surface to accommodate the CNG. The cylindrical body has a diameter and a length. Each dome has a base diameter and axial height equal to the diameter of the cylinder. The overall length of the pressure vessel is defined as the sum of the axial length of the cylindrical body and the axial height of the dome. The ratio between the length of the pressure vessel and the diameter of the cylindrical body is 1 to 2 or 1 or 2, so that the resulting pressure vessel is compact and has a good internal volume ratio per unit surface.

Description

Optimized container {OPTIMIZED VESSEL}

The present invention relates to a pressure vessel, particularly a pressure vessel for containing compressed natural gas (CNG). Moreover, the present invention relates to a pressure vessel that is substantially optimized for conformity of shape.

The present invention also relates to a method of manufacturing the pressure vessel and a means of transporting the pressure vessel over the water or onshore.

Cylindrical pressure vessels for storing and transporting CNG are well known in the art. Several characteristic advantages relate to the cylindrical shape of the container. For example, such a container may be stacked laterally, vertically, or horizontally, and may also be disposed within a module or cell designed to accommodate many such containers.

If the length of the container is a multiple of its width, for example 3 times (or 2.5 times), the container will be comparable to a relatively elongated structure. This major axial dimension of the vessel can favorably affect the stackability of the vessel and also the possibility of grouping a plurality of modules including such stacked vessels, thus making space utilization efficient (i. E. The allowable unused space between the adjacent containers can be small).

Cylindrical pressure vessels also relate to some degree of maneuverability and ease of handling due to the major axis dimensions of the cylinder. It is therefore not difficult to slide the pressure vessel horizontally or vertically along its longitudinal axis to slide the cylindrical pressure vessel away from its position and position as its module or support.

Further, if the cylindrical container is a cylindrical container (e.g., a container wrapped with a carbon fiber-reinforced polymer) in which the composite material is wrapped, it is relatively easy to wind the composite onto the inner substrate or liner using known fiber winding techniques. In these procedures, fibers that are typically impregnated with a resin are wound around the liner in a continuous fashion to form a hoop shaped coil, which is centered on the longitudinal axis of the container and has a longitudinal (axial) dimension And are uniformly arranged on the surface. In this "hoop wrapping ", a fiber distribution machine or head, in which a cylindrical substrate or liner is rotated about its associated axis and then moves linearly near the rotating cylinder, And so on and so on. The coil may be a contact coil that causes the fibers to come into contact with each other, or may be spaced from one another, such as a corkscrew.

Cylindrical pressure vessels are also relatively uncomplicated to manufacture using other techniques. This is because at least in principle such a container can be thought of simply as a pipe with an end cap. Thus, in the case of a cylindrical cylindrical pressure vessel, the cylindrical portion of the vessel can be manufactured using a squeezed pipe manufacturing method and then the end cap can be welded to the end.

Older pressure vessels are also known in the art, which can also be used to store and transport CNG, but are actually used less frequently than cylindrical pressure vessels.

One advantage of spherical containers is that they have an advantageous volume to surface ratio, so that a given amount of CNG can be stored and transported inside the lightest container (smaller surface area will result in fewer materials in the container structure, A light container is obtained). Because of the optimum volume to surface area ratio, spherical containers provide better thermal insulation (or less heat loss characteristics) than equivalent cylindrical vessels, i.e., they use less insulation material per unit volume of fluid contained, The same overall insulation coefficient can be obtained.

Also, in terms of strength, spherical containers are better than equivalent cylindrical containers. This is due to the manner in which the internal pressure exerts a load on the wall of the container, the load being transferred substantially uniformly around the entire surface area of the spherical container, but in the cylindrical container the load varies from position to position. Thus, for a given internal pressure of CNG, the spherical container may have an average structural wall thickness that is somewhat thinner than an equivalent cylindrical container. Thus, a container lighter than a cylindrical container is obtained. However, in the case of composite containers formed from wound fibers, this effect may be reduced by the net longitudinal strength of their windings, so an additional layer is needed to handle and resist the multi-directional load.

In addition, spherical containers tend to roll naturally and have wider dimensions for a given containment volume, so they are not advantageously comparable to cylindrical containers in terms of handling and handling / laminating ease / efficiency.

For fiber spinning of composite shells for spherical containers, this is known to be more difficult than winding of composite shells for cylindrical containers. This is because there is no major axis in which the container can rotate such that the fibers can be received inside the shell with a regular hoop or loop. Thus, in the case of a spherical container, the fiber winding process becomes more complicated and care must be taken when positioning the fibers around the sphere. Thus, the fibers are wound around the sphere to obtain the required thickness uniformity and intensity uniformity.

"Spiral winding" is known as a preferable method for winding in a spherical shape. (Of fibers) still appear as coils on the substrate surface. Also, the winding around the spherical pressure vessel can still follow an open spiral pattern, i.e. the loops do not abut against the preceding loops (although such butting is possible in a cylindrical container). However, a regularly and linearly extended hoop or loop pattern (reference numeral "154" in Fig. 3), more commonly used for cylindrical winding, substantially follows the longitudinal center axis of the container ), The loops are instead wound in an axis-rotated manner so that the center of rotation of each loop is still substantially on the center axis, but also the center of rotation of each subsequent loop is at substantially the same point, This point is a substantially fixed point substantially at the center of the sphere (taking into account the imperfections in the thickness of the yarn and the uniformity of the yarn, there will actually be some variation around the fixed center point, but the deviation will be small).

As is apparent from the foregoing, for a uniform winding using a spiral winding process, each successive loop is rotated about its leading edge with a given angle around its center, but at a constant angle to the fixed axis and It maintains a constant center point rather than having a constant displacement along its axis.

Preferably, the given angle remains constant throughout the spiral wound process.

A feature of this "spiral wound" is therefore that the continuous hoops continuously rotate around the center of the sphere, with each hoop having a radius substantially equal to the diameter of the spherical winding layer.

However, as a disadvantage of spherical pressure vessels, spherical pressure vessels require more reinforcing fibers per unit of reinforcement to achieve the required yield strength. This is because the curvature of the wall is two-dimensional, so the circumferential stress does not act in the main direction. The circumferential stress is unidirectional and, therefore, in the case of a fiber-wound sphere, more fiber layers are needed to provide adequate multi-directional reinforcement.

This difference can be measured, for example, with reference to the total required yield strength ( _y ) of the structural material of the vessel wall, in order to increase [sigma] _y for a spherical pressure vessel made of a steel liner having a wall thickness & The fiber per unit surface area required for the layer (which provides its strength? _Y ) becomes greater than that of an equivalent cylindrical container (i.e., a container made of a steel liner also having wall thickness "d"). In other words, in order to achieve the same level of total yield strength, more fibers should be wound around the spherical container than the generally cylindrical container to cope with the unidirectional nature of the load. Therefore, the overall thickness of the over-wrap for reinforcement becomes thicker. Nevertheless, this is compensated for by the fact that the total area of the wall is smaller and the thermal insulation coefficient of the spherical container of the thicker wall wound into filaments will be higher than the equivalent cylindrical container wound with filaments.

It is therefore an object of the present invention to provide a more optimized pressure vessel, i.e. a pressure vessel having the above-mentioned many advantages and a drawback less.

According to a first aspect of the present invention, there is provided a pressure vessel for containing CNG,

A cylindrical body having a diameter and an axial length;

Two cylindrical ends each having an axial depth; And

CNG inlet / outlet,

The cylindrical body and the cylindrical end together define a generally concave internal volume having a generally concave internal surface for receiving CNG,

The total length of the pressure vessel is defined as the sum of the axial length of the cylindrical body and the corresponding axial depth of the cylindrical end, each measured internally and excluding the length of the CNG inlet /

The ratio between the total length of the pressure vessel and the inner diameter of the cylindrical body is 2: 1 to 1: 1 and comprises values of 2: 1 and 1: 1.

In addition, a pressure vessel for storing CNG is provided,

A cylindrical body having a diameter and an axial length;

Two cylindrical ends each having an axial depth; And

CNG inlet / outlet,

The cylindrical body and the cylindrical end together define a generally concave inner surface and a generally convex outer surface defining an internal volume for receiving CNG,

The total length of the pressure vessel is defined as the sum of the axial length of the cylindrical body and the corresponding axial depth of the cylindrical end, each measured internally and excluding the length of the CNG inlet /

The ratio between the total length of the pressure vessel and the outer diameter of the cylindrical body is 2: 1 to 1: 1 and comprises values of 2: 1 and 1: 1.

The term CNG refers to a compressed natural gas that is a well-flowing fluid, that is, gas and liquid hydrocarbons that have been received untreated from the source or processed compressed natural gas (less impurities).

The CNG fluid may contain a variety of potential components at variable mixing ratios, some of which are gaseous and the other of which are liquid or a mixture of the two. These components generally comprise one or more of the following compounds: C ₂ H ₆ , C ₃ H ₈ , C ₄ H ₁₀ , C ₅ H ₁₂ , C ₆ H ₁₄ , C ₇ H ₁₆ , C ₈ H ₁₈ , C ₉ + hydrocarbons, CO ₂ and H ₂ S, and potentially liquid toluene, diesel and octane and other impurities / species.

Preferably, at least one of the cylindrical ends is dome-shaped when viewed in the absence of an inlet or outlet or neck.

Preferably, the dome has a substantially constant radius around at least 90% of its radial extension. However, a short extension may be mixed with the cylindrical body to reduce the stress concentration within the material of the container when pressure is applied to the container.

Preferably, the two cylindrical ends are of such a dome shape.

Preferably, the two cylindrical ends have the same axial depth. This can be accomplished in similar or different shapes.

Preferably, the volume and surface of the container are generally axisymmetric with respect to the axis of the cylindrical body.

Preferably, the outer diameter of the cylindrical body is 5 m to 50 m. The diameter of 30 m is also preferable.

Preferably, the vessel is designed to withstand an internal pressure of 50 to 150 bar. Generally, the vessel is designed to withstand an internal pressure of at least 150 bar.

Preferably, a fiber-reinforced polymer layer is provided around the container.

Preferably, the fiber-reinforced polymer layer is provided all around the cylindrical body of the container.

Preferably, the fiber-reinforced polymer layer is a hoop-wrapped fiber-reinforced polymer layer.

Advantageously, said fiber-reinforced polymer layer covers at least 80% of the cylindrical end of the container or up to the neck of said inlet or outlet and the cylindrical body.

Preferably, the cylindrical end is a geodesic dome.

Preferably, the cylindrical end has a radius that is at least half the total length of the container as defined above.

Preferably, the fiber-reinforced polymer layer is spirally wrapped over the cylindrical end through a rotating spiral hoop.

Advantageously, the wound hoop is abutted to a neighboring hoop in each layer to provide a surface covering fiber layer. Instead, the hoops can be separated from each other.

Preferably, a plurality of layers of fiber reinforcement are formed on the surface of the container. The layers may alternate between the hoop winding and the helical winding, and the angle may vary between adjacent layers or even between corresponding layers spaced apart (spaced hoop windings). The hoop (cylindrical) portion may be twice the amount of fiber-reinforced polymer than the end portion due to the load distribution in the container structure.

Preferably, the container may comprise a metal liner. The liner may have a cross-sectional thickness of 1 to 50 mm. Other thicknesses are also possible, the thickness can be in this range, or even thicker than this range, especially when the liner has to withstand the winding pressure. The larger the diameter, the greater the risk of liner collapse, and thus the liner becomes thicker. Preferably, the thickness is less than or equal to 10 mm (or less than 1% of the diameter) and usually the liner is unstructured in the final product, ie, the winding / layer, rather than the liner, provides most of the structural strength.

Preferably, the container comprises a polymer layer made of one of a polyester resin, a vinyl ester resin, an epoxy resin, a phenol resin, a high purity dicyclopentadiene resin, a bismaleimide resin and a polyimide resin.

Advantageously, said container comprises a wound fiber reinforcement, said wound fiber reinforcement comprising at least one of carbon fiber, glass fiber and Kevlar (aramid fiber).

Preferably, a layer of fiber-reinforced polymer is applied onto the surface of the container. This layer may have a thickness of at least 200 mm in the case of a container having a larger diameter, for example 10 m or more.

A method of manufacturing a pressure vessel is also described.

According to another aspect of the present invention, CNG transportation means including one or more pressure vessels as described above may be provided. The transportation means may be a vessel.

The present invention provides, for example, a module for transporting CNG in the hull of a ship, comprising a plurality of vessels as described above, the vessels being coupled together via pipes.

BRIEF DESCRIPTION OF THE DRAWINGS These and other aspects of the invention will now be described, purely by way of example, with reference to the accompanying drawings, in which: Fig.

Figure 1 shows a generally cylindrical pressure vessel.
Fig. 2 is an enlarged cross-sectional view of one portion of Fig. 1;
Fig. 3 schematically shows a method of wrapping a fiber in a pressure vessel according to one aspect of the present invention. Fig.
4 schematically shows a method of wrapping a fiber in a spherical pressure vessel.
5 schematically shows a graph generally illustrating a cylindrical pressure vessel and a spherical pressure vessel in terms of comparison between volume to surface area ratio and maneuverability, wherein a comparison zone in which the pressure vessel of the present invention can be located is generally also shown have.
6 is a schematic cross-sectional view of a container according to the present invention.

1 shows a double-layer cylindrical pressure vessel for storing and transporting CNG. The shape of the container generally depends on the shape of the container known in the prior art. Thus, the container 10 is generally cylindrical in shape and the structure or body extends primarily in one direction (in the direction of the longitudinal axis of the container), so that the container is more cylindrical than spherical.

A wall having two layers is formed in the container (see Fig. 2). The inner layer (i.e., liner) 100 is made of steel, such as low carbon steel. The outer layer (which may be a composite stiffener) is made of a fiber reinforced composite polymer 20, such as a carbon fiber reinforced composite (CFRC). Other materials known in the art are also possible.

The inner layer is generally in direct contact with CNG, and the outer layer is generally exposed to the external environment.

In this container 10, the thicknesses of the two layers 100, 200 are shown to be approximately the same. However, the thickness may vary. For example, the thickness of the inner layer (liner 100) may be such that the inner layer provides little or no structural capability during CNG transport. Instead, the outer layer 200 will provide the structural capability of the container (i. E. The strength needed to withstand the high pressure inside the container to which these containers will be exposed) (these containers are used for CNG transport, Lt; RTI ID = 0.0 > CNG < / RTI > is substantially liquid). Thus, the nominal pressure at which a prior art container is designed to withstand is generally about 250 or 300 bar at 20 占 폚. This pressure can therefore be considered to be a pressure that the container can safely withstand in design.

The use of metal liners is common in such a container industry because metal liners are often easier to provide both the necessary CNG containment (metal liner is generally "airtight") and corrosion resistance as CNGs are often raw or untreated It can be designed. Stainless steel can also be highly resistant to salt attack and chemical attack by many or all of the many aggressive materials commonly found in stored CNG.

The container of Figure 1 is also shown to have two ends 11, 12, the shape of their end portions 11, 12 being shown is new. In addition, their ends are different from each other.

1, bottom end 12 has an inlet / outlet opening 120 for loading CNG 20 into container 10 and off-loading the container . A 12 inch (30 cm) exit is preferred. The outlet is typically adapted to connect a plurality of such vessels to the piping connecting them. On the other hand, the top end 11 has a manhole 30 for internal inspection of the container. This manhole is shown as being bolt-fastenable. If the bolt is removed to remove the cap, the user can enter the container for inspection. Typically, the manhole is an 18 inch (45 cm) manhole or 24 inch (60 cm) manhole.

If the ends are different and especially different in size, the geometry of the top and bottom ends 11, 12 is also slightly different. The general shape of the ends 11, 12 may be generally dome-shaped, even with a neck and a cap, but the steady dome is slightly deeper in the axial direction and the bottom dome is slightly more flat or camshaft in the axial direction. However, other configurations are possible.

In use, the top end 11 is usually located at the uppermost position.

Thus, the vessel 10 has a cylindrical body 40 and a top and bottom end or dome 11, 12, which together define the overall axial internal length of the vessel. The cylindrical body 40 also defines the inner diameter of the container. As shown in Fig. 1, they give a length: diameter (inner diameter) ratio. The length is measured between points A - A (i.e. between the bases of the throat) and the diameter is measured between points B - B located on opposite inner surfaces of the vessel.

With this ratio being at least 2.5: 1, the vessel will have a cylindrical appearance. In this embodiment, the ratio is about 5: 1.

The container of the present invention may have many of many of these characteristics. In particular, containers are generally designed to withstand similar safety work pressures. However, the shape, form, and configuration of the container of the present invention will generally be different from each other as will be described later.

3 shows a pressure vessel 110 according to the present invention. The container is more compact in the pressure vessel of FIG. 1 in the axial (longitudinal) dimension. This is because the internal length to diameter ratio for this container is approximately 2: 1. Again, the internal length is the internal length of the main chamber, that is, the length to the base of the neck (only one neck in this embodiment). The internal length is measured along the longitudinal axis of the vessel along the points A - A in Fig. The inner diameter is measured across the middle from the inner sidewall along point B-B in Fig. If the sidewall is not substantially perfectly cylindrical (e.g., if the sidewall has a gentle curvature), the measurement may be the maximum inner diameter.

According to the present invention, the vessel has an internal length to diameter ratio ranging from 1: 1 to 2.5: 1, or, more specifically, up to 2: 1. The container also generally has a cylindrical cross-section for defining its longitudinal axis. In addition, the container generally has an end wall with an internally concave surface (recessed in both the longitudinal and transverse directions when viewed from the inside). Also, one or more of these end walls generally have an inlet / outlet, wherein the connection from the inner concave surface of the end wall to its neck forms a concave / convex cross-section (convex in the longitudinal direction and concave in the transverse direction) ).

The two end walls 112 (viewed from left and right in FIG. 3) may be more elongated (see FIG. 6) than they appear, but may be smoothly blended into a cylindrical section 100 )). However, the mixed connection reduces the stress concentration at the connections when dropping the CNG into the container (i.e., increasing the pressure inside the container). The blended joints also aid in the winding operation first because sharp angles are more unpredictable in determining the tension required to place the filaments and to ensure tight lamination without rupturing or damaging the filaments.

As noted above, it is preferred that the range of possible internal length to diameter ratios may include a ratio of 1: 1. A perfectly spherical container would also have a ratio of 1: 1, because the ratio between its internal length and internal diameter would be 1, regardless of the direction of the axis. Thus, the 1: 1 ratio itself is not new. However, they do not have any kind of body between the substantially spherical intermediate portion or the two domed ends. Instead, the spherical container may be defined as being composed of only two domed ends, both domed ends being hemispherical. Therefore, spherical containers are excluded from the scope of protection of the present invention.

In an embodiment of the present invention, the internal length of the container, such as a prior art container, is defined by a cylindrical portion of the container or an internal length of the body (the body defining a longitudinal axis of the container through the middle of the container) (Or corresponding axial depth) of the end portion at both ends of the end portion.

Now, the winding process according to the second aspect of the present invention will be described in more detail.

Referring to FIG. 3, it is shown that the stainless steel liner 1100 is undergoing a fiber winding procedure. The procedure includes hoop wrapping forming a loop 154 defining a linear spiral 154 and spiral winding forming a rotating helix with sequential loops 155, 156, 157, 158.

A basic feature of the wrapping process of the container 110 is that the fibers (ending at or past the second point 153, starting at the first free end 152), which may be monofilaments, tape fabrics of fibers, or combinations thereof, Along the body 1000 in a repetitive, rotating spiral defined by the rotary loops 155, 156, 157 and 158 and along the body 1000 before passing back and forth over the two ends 111, Or spiral 154 as a coil. Therefore, the winding process is a combination of the two forms described above with respect to the cylindrical container and the spherical container, namely a combination of hoop wrapping and spiral wrapping, in which the fibers are alternately laid over the cylindrical portion and the end wall at various angles.

More specifically, the initial winding begins at the first end 152 (its position is arbitrary, but shown as being close to one end of the container or the mixed corner 111). And the winding passes along the cylindrical portion 1000 in a loop having a constant angle to the circumference of the container to form the spiral shape 154. Then, after being briefly wrapped around the first end 112, the fibers are rolled at an angle to initiate a return loop or arc 155 again towards the other end, perhaps again near the blended corner 111 And a rotating spiral wrapping is performed using a relatively forward and aft end-end relative rotating loops 155, 156, 157, 158, 151, each loop having a substantial And in this spiral wrapping, the wrap angle is continuously changed to maintain the center of rotation at the center point 150 thereof. The spiral wrapping then starts again along the cylindrical portion with the longitudinal spiral to form the third layer of composite and is converted to hoop wrapping. Which continues to alternate layers until a composite of sufficient thickness is formed to achieve the desired strength for the container 110, while the other layers may be provided at staggered angles.

It is common to schematically show that they are formed in an open loop, but it is common to confront the continuous loop 154 or successive helix 155, 156, 157, 158 with a preceding loop or helix, Each pass of the helical wrap forms a surface cover layer of the loop (and if the fibers are in tape form, such butt can cover the surface with less rotation).

In a preferred technique, the fibers are impregnated with a suitable polymer or resin (matrix) before (or even during) winding. As a result, the wound fiber is in its final position on its surface when it is being wound on the surface of the container, i.e. it is already in the proper resin layer (the material which needs to be hardened to finish the manufacturing process). However, each fiber layer can be wound onto a pre-applied resin base, and a new resin layer is then applied over the new layer, e.g., by spraying. Another alternative is to spray continuously. Nevertheless, the method includes forming a resin bonded fiber layer to provide the desired composite structure.

The coils 154 of the helical formations 155, 156, 157 and 158 are provided by delivering fibers, filaments or tape while the container 110 is rotating about its longitudinal axis. Dispensing tape or rotating the helix along its axis to form a longitudinal coil may be accomplished by a machine or machine that moves linearly next to the vessel 110 parallel to the axis of the vessel 110 as the vessel 110 rotates (Such as a tape feed head) (even though the spiral loop would extend in the longitudinal direction, the vessel 110 would be stationary at that moment).

The tape supply head has a variable transverse velocity along its axis, and likewise the container 110 has a variable rotational velocity.

As can be seen from the above, the principle of the two hoop and helical winding is inherently simple. Therefore, these methods can be performed using conventional winding apparatuses.

It is possible to obtain a certain range of wrap angle (the angle formed between the transverse surface of the container and the fiber itself in the circumference of the container 110) and to change the rotational speed of the container or the transverse speed of the mechanical part You can choose.

The tape feeding speed from the head is appropriately changed so that the tape is applied to the surface of the container 110 in a suitably tight state.

Preferably, the tape is struck against a previously applied hoop or loop (generally a preceding hoop or loop). With a tight butt, uniform strength properties can be maintained. In this regard, the hoops as shown in Fig. 3 (hoops apart from one another) are not the preferred arrangement for the hoops on which they are placed. However, the hoops are provided so as to improve the clarity of the drawings.

The control of the winding position may include changing the rotation speed of the container and the movement amount of the head. It will also vary depending on whether the hoop is being applied to the longitudinally extending spiral or whether a rotated helix is applied. In the case of a hoop, the tape feed head traverses the length of the cylindrical body 1000 at a constant speed in the first direction, and the tape is fed out of the head at a constant speed. However, when the tape supply head reaches the first end of the cylindrical portion 1000, the head is decelerated and the direction reversed and a loop or loop of fibers is formed on the first end 112 before being returned to the other end of the container 110 Thereby controlling the looping process of placing the arc 155 in a spiral manner. The transverse speed of the head towards the other end can be controlled to be higher than the speed of the front transverse direction (transverse to the first direction) Thereby extending the helical loop around the first side of the housing 110. The head then decelerates again, reverses its direction, and again places another loop or arc 156 around the opposite end before traversing in the first direction at an increased speed (a spiral loop at the opposite side of the vessel 110) To apply continuously). Therefore, continuous control of the head speed and the rotational speed of the vessel (which need to be slowed to achieve proper winding without causing excessive tensioning of the tape) is provided for the winding machine.

Finally, once the appropriate number of helical loops 155, 156, 157, 158 are obtained, the device is returned to the mode for providing a new hoop wrap portion 154 along the cylindrical body 1000 of the container 110 .

While it is desirable to maintain a constant angle with respect to each of the hoop tufts layers, each of the hoop tufted layers may be provided at a different angle to the previous hoof tufted layers.

The end 112 of the cylindrical container 110 is generally domed. In order to facilitate its helical wrapping, the domes are preferably geodesic surfaces with respect to each other, that is, the dome is a common circle or is interdigitally compatible, Lt; RTI ID = 0.0 > 150 < / RTI > Therefore, assuming that a constant radius is provided for their surfaces, the minimum radius given to the dome, while still having a side-by-side or side-by-side compatible configuration according to the above definition definition, Half. Although some rounding is still desirable to reduce the degree of stress concentration at their connections, the rounding of the connections between their surfaces and the cylindrical body must be kept to a minimum to maximize the degree of geodesic or geodesic compatible surface.

The advantage of these geodesic or geodetic compatible surfaces to the end 112 is that the spiral winding of the fibers 155 around the dome can be more easily obtained. This is because the fibers can be wound under tension without slippage on the side of the dome. Even if tension is applied to the fibers, the fibers tend to stay in place on the surface after winding or only to slide toward the center of the end, the latter occurring on a side-compatible compatible surface. In the latter configuration, the windings are applied so as to contact the neck of the outlet 160 or to come close to the center in contact with the windings (or neighboring windings available to its magnetic field) already in contact therewith so as to intersect the center of the end portion 112 , So that each subsequent winding is tightly abutted against the more proximal winding, thereby providing a stable and yet tightly arranged surface covering for that end. The winding is stable, so it will not simply slip on the side of the dome. However, such a slip tends to occur if the radius of the end is less than half the inner length of the container.

Optimal side effects are obtained in the case of surfaces which draw a common circle, preferably a cadastral condition, in which the windings can be wound across the next end without passing through the center of their ends without slippage at the ends .

The inlet 160 of the container can be a composite material wrapped using a winding machine, which is usually done in the next step to another device. Thus, initially this portion 160 of the vessel 110 is not wrapped at the same time as it envelops the cylindrical body 1000 and the dome-shaped end 112.

An alternative winding process is shown in Fig. A generally spherical stainless steel liner 210 is wrapped in fibers 315. As is usual, fibers 315 are not wrapped around a portion of the spherical shape corresponding to the inlet / outlet holes 230. Nevertheless, it is difficult to wrap the fibers 315 around the sphere, since it requires rotation of several degrees.

In Fig. 4, the process is obtained by the provision of the fiber delivery head 300 which is located on the support call 311 rather than the linear line as described above. Thus, the fiber delivery head 300 can move up and down along the arc 311.

In addition, the support rods 311 can be rotated 313 about their own support portions 312.

The spherical container itself is also located on a rotating support (not shown) so that the container can rotate (211) around the axis. Preferably, the axis is a vertical axis.

In another embodiment, the spherical container may be a filament wrapped using a known three-dimensional fiber delivery head.

The fibers wrapped around the spherical container using these machines will follow a rotating spiral pattern 316 similar to the spiral pattern described above for the container of FIG. The fibers are wrapped in a series of connecting coils having a radius along the circumference of the sphere on which they are placed. Therefore, the fibers are centered at the center 350 of the sphere. Thus, the fibers will not slip on the surface of the sphere under tension with it (similar to the above cited case).

As described above, in this kind of container (spherical container), more fiber is required per unit reinforcement required due to the curvature of the container wall in one direction. Thus, for windings in each successive layer across the surface of the sphere, the windings are applied across multiple layers at a number of different angles. A number of axes and arcs 311 facilitate this.

5 is a chart showing relative positions of a generally spherical pressure vessel (upper half), a generally cylindrical pressure vessel (lower half) and a pipe (bottom line), and these vessels are compared with their ease of manufacture x axis).

A spherical pressure vessel is provided in the upper half (large y-axis value) because the vessel has the highest volume to surface area ratio. However, the spherical container is relatively difficult to manufacture for the reasons described above, so it is shown on the left side of the chart and has a low x-axis value indicating a lack of ease of manufacture.

Cylindrical containers are relatively easy to manufacture, because they are easy to wrap. Thus, a cylindrical container has a higher x-axis value than a spherical container. However, the cylindrical container is not ideal in terms of volume to surface ratio. Therefore, in a cylindrical container, a lower y-axis value is given to the spherical container.

Finally, the pipe is much easier to manufacture than a cylindrical container, and there is no need to make an end cap. Therefore, the pipe is highly rated for ease of manufacture. However, since pipes generally have a smaller cross section, they are inefficient in terms of volume to surface area ratio. Therefore the pipe is very low down the y axis.

The size and shape of the container of the present invention are determined so as to be located at an intermediate position between the spherical container and the cylindrical container in the chart of Fig. This is indicated by a cloudy area labeled "optimized sphere ". Therefore, the container of the present invention is a relatively compact pressure vessel, which is not a spherical container and is too short in diameter because it includes a substantially cylindrical portion (2: 1 to 1: 1 Lt; RTI ID = 0.0 > ratio) < / RTI >

Another embodiment of the container 410 according to the present invention is shown in Fig. Where the ratio of length 412 to depth 411 is approximately 1.05.

In addition to measuring the internal dimensions, external dimensions may be used. After all, it is easier to measure external dimensions when access to the inside of the container is not allowed. Again, the neck of the inlet / outlet (s) is ignored. However, according to another aspect of the present invention, the external dimensions have a ratio of 2: 1 to 1: 1.

The container 410 of this last embodiment is made of a single layer of structural steel and the thickness is determined by the maximum safe working pressure required for the design of the vessel 410.

It is possible to provide a high-pressure or low-pressure container. Therefore, containers of similar size may have different pressure ratings depending on the strength of the container wall, and so on. In this last embodiment, the vessel 410 may be designed to be a medium pressure (e.g., up to 150 bar) vessel.

The container body may be made in a pipe shape, in which the two end dome 415, 416 are welded to the body. One of the end dome is provided with an entry / exit aperture 420.

In the embodiment of FIG. 6, the outer diameter D of the vessel 410 is 5 m and the length L of the vessel is about 5.25 m. The thickness of the steel wall is probably less than 15 cm.

In another embodiment, the vessel has a diameter of up to 50 m, and these vessels are large because they carry and transport large amounts of CNG.

The container of Figure 6 is relatively easy to manufacture and is also a cylinder with an end cap, thus representing a relatively inexpensive steel container for storage of CNG. The vessel has a particularly advantageous volume-to-surface ratio and is particularly suited to the case where a large amount of CNG must be stored or transported.

The volume can be increased by lengthening the length of the cylindrical portion and increasing the diameter. However, when larger diameters are needed, the pressure rating of the vessel needs to be re-evaluated and a thicker steel may be needed.

These containers, which are known as optimized spheres, are particularly suited for use in high-capacity and medium-range pressures in the CNG storage and transportation field.

Because of the presence of the intermediate cylindrical portion, the container of Figure 6 is relatively easy to hoop wrap with reinforcing fibers, thus increasing the strength without increasing the container weight, and the composite reinforcement is lighter than steel.

The convenience of the so-called optimized sphere is essentially a result of the combination of a relatively high volume-to-surface ratio and the maintenance of the cylindrical axis, so that the optimized sphere can be manufactured more easily at a reasonable cost.

Instead of a metal liner, a plastic liner such as a high density polyethylene or a liner made of high purity polydicyclopentadiene may be used.

The liner can also be replaced by a removable liner or an internal removable scaffolded liner, in which case the liner is removed after winding and the resulting composite itself provides a complete container.

The pressure vessel can contain, for example, raw natural gas at compression (e.g., CO ₂ tolerance of up to 14%, H ₂ S tolerance of up to 1,000 ppm or H ₂ and CO ₂ gas impurities or other impurities or corrosive species Such as raw CNG or RCNG, H ₂ , or CO ₂ or treated natural gas (methane), or raw natural gas or partially treated natural gas), such as raw gas directly from the borehole . However, a preferred use is CNG transportation, which is handled to a standard that can be delivered to original CNG, partially treated CNG or clean CNG (end users, such as commercial, industrial or residential users).

CNG can contain a variety of potential ingredients in variable proportions, some in the gaseous state and the other in a liquid state or a mixture of the two. These components generally comprise one or more of the following compounds: C ₂ H ₆ , C ₃ H ₈ , C ₄ H ₁₀ , C ₅ H ₁₂ , C ₆ H ₁₄ , C ₇ H ₁₆ , C ₈ H ₁₈ , C ₉ + hydrocarbons, CO ₂ and H ₂ S, and potentially liquid toluene, diesel and octane and other impurities / species.

The present invention has been described above purely by way of example. It is to be understood that specific changes to the above-described embodiments are possible within the scope of the invention as defined in the appended claims.

The scope of the present invention is defined by the following claims.

Claims (29)

As a pressure vessel for storing CNG,
A cylindrical body having a diameter and an axial length;
Two cylindrical ends each having an axial depth; And
CNG inlet / outlet,
The cylindrical body and the cylindrical end together define a generally concave internal volume having a generally concave internal surface for receiving CNG,
The total length of the pressure vessel is defined as the sum of the axial length of the cylindrical body and the corresponding axial depth of the cylindrical end, each measured internally and excluding the length of the CNG inlet /
Wherein the ratio between the total length of the pressure vessel and the inner diameter of the cylindrical body is from 2: 1 to 1: 1 and comprises a value of 2: 1 and 1: 1. As a pressure vessel for storing CNG,
A cylindrical body having a diameter and an axial length;
Two cylindrical ends each having an axial depth; And
CNG inlet / outlet,
The cylindrical body and the cylindrical end together define a generally concave inner surface and a generally convex outer surface defining an internal volume for receiving CNG,
The total length of the pressure vessel is defined as the sum of the axial length of the cylindrical body and the corresponding axial depth of the cylindrical end, each measured internally and excluding the length of the CNG inlet /
Wherein the ratio between the total length of the pressure vessel and the outer diameter of the cylindrical body is from 2: 1 to 1: 1 and comprises a value of 2: 1 and 1: 1. 3. The method according to claim 1 or 2,
Wherein at least one of the cylindrical ends has a dome shape when viewed in the absence of an inlet or outlet or a throat. The method of claim 3,
Wherein the dome has a substantially constant radius around at least 90% of its radial extension. The method according to claim 3 or 4,
Said two cylindrical ends having such a dome shape, said pressure vessel for containing CNG. 6. The method according to any one of claims 1 to 5,
Said two cylindrical ends having the same axial depth. 7. The method according to any one of claims 1 to 6,
Wherein the volume and surface of the vessel are generally axisymmetric with respect to the axis of the cylindrical body. 8. The method according to any one of claims 1 to 7,
Wherein the cylindrical body has an outer diameter of 2 m to 5 m. 9. The method according to any one of claims 1 to 8,
And the outer diameter of the cylinder is 5 m to 50 m. 10. The method according to any one of claims 1 to 9,
Pressure vessel for storing CNG, intended to withstand internal pressures up to 150 bar. 11. The method according to any one of claims 1 to 10,
A pressure vessel for containing CNG, wherein a fiber reinforced polymer layer is provided around the vessel. 12. The method of claim 11,
Wherein the fiber reinforced polymer layer is provided throughout the cylindrical body of the vessel. 13. The method of claim 12,
Wherein the fiber-reinforced polymer layer is a Foam-wrapped fiber-reinforced polymer layer. 12. The method of claim 11,
Wherein the fiber-reinforced polymer layer covers at least 80% of the cylindrical end of the vessel or neck of the inlet or outlet and the cylindrical body. 15. The method according to any one of claims 1 to 14,
Wherein the cylindrical end is a geodesic dome. 16. The method according to any one of claims 1 to 15,
Wherein the cylindrical end has a radius that is at least half the total length of the container as defined in claim 1. A pressure vessel for containing CNG. 17. The method according to claim 15 or 16,
Wherein the fiber reinforced polymer layer is spirally wrapped over the cylindrical end through a rotating spiral hoop. The method according to any one of claims 11 to 14 or 17,
Said hoop being abutted against a neighboring hoop in its layer to provide a surface covering fiber layer. 19. The method according to any one of claims 1 to 18,
A pressure vessel for containing CNG, wherein a plurality of layers of fiber reinforcement are formed on the surface of the vessel. 20. The method according to any one of claims 1 to 19,
And a metal liner having a cross-sectional thickness of 1 to 50 mm and less than 1% of the diameter of the vessel. 21. The method according to any one of claims 1 to 20,
A pressure vessel for containing CNG, comprising a polymer layer made of one of polyester resin, vinyl ester resin, epoxy resin, phenol resin, high purity dicyclopentadiene resin, bismaleimide resin and polyimide resin. 22. The method according to any one of claims 1 to 21,
Wherein the wound fiber reinforcement comprises at least one of carbon fiber, glass fiber and aramid fiber. 23. The method according to any one of claims 1 to 22,
A pressure vessel for containing CNG, wherein a layer of fiber reinforced polymer is applied on the surface of the vessel, the layer having a thickness of at least 50 mm. A pressure vessel as described above with reference to any one of Figs. 3, 4 or 6 substantially. 24. A method of manufacturing a pressure vessel as claimed in any one of claims 1 to 24 substantially as hereinbefore described with reference to any one or more of the accompanying drawings. 24. A CNG transport vehicle comprising at least one pressure vessel according to any one of the preceding claims. 27. The method of claim 26,
Ships in the form of CNG transport vehicles. 27. The method of claim 26,
CNG transport vehicle in the form of road or rail car. A module for transporting CNG comprising a plurality of containers according to any one of claims 1 to 24, the containers being joined together through pipes.

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