Liquid pipeline, in particular a liquid pipeline for underground transport of hot liquids

Abstract

Liquid pipeline, in particular a liquid pipeline for underground transport of hot liquids A liquid pipeline (1A) comprises an outer casing (3), a medium-carrying pipe (5) within it, and insulation material between the outer casing (3) and the medium-carrying pipe (5). At one end of the liquid pipeline (1A), a baffle (9) is positioned against the insulation material. The baffle (9) is provided with a circular hole (11) through which the medium-carrying pipe (5) extends. The baffle (9) is connected liquid-tight to the medium-carrying pipe (5) over the entire circumference of the medium-carrying pipe (5) and to the outer casing (3) over the entire circumference of the outer casing (3). The baffle forms a water barrier, which, in the event of damage, limits the internal spread of penetrating (ground)water along the length of the liquid pipeline. As a result, when the liquid pipeline is repaired, at most the section of the liquid pipeline between two baffles on either side of the damage needs to be replaced.

Description

[0001] Liquid pipeline, in particular a liquid pipeline for underground transport of hot liquids

[0002] DESCRIPTION:

[0003] Technical field of the invention

[0004] The invention relates to a liquid pipeline, in particular a liquid pipeline for underground transport of hot liquids, comprising an outer casing, a medium-carrying pipe located within the outer casing and extending with its ends from the outer casing, and insulation material located between the outer casing and the medium-carrying pipe and being in contact with the inside of the outer casing and the outside of the mediumcarrying pipe, at, at least one end of the liquid pipeline, a baffle is present against the insulation material, the baffle being provided with a circular hole, and the mediumcarrying pipe extending through the hole. More specifically, the invention relates to a liquid pipeline for district heating, consisting of a network of underground liquid pipelines through which warm / hot water flows. This allows houses / buildings and / or hot tap water for tap water and showers to be heated. The heat source varies from a power plant or a waste incinerator to geo- / aquathermy and residual heat from data centers. The most common customers are private homeowners, housing associations, and business customers (office owners).

[0005] Background of the invention

[0006] A liquid pipeline according to the preamble of claim 1 is known from US 3 560 287 Al. In practice, the outer sheathing can become damaged by, for example, excavation work, subsurface settlement, or expansion due to temperature fluctuations. This can allow (ground)water to penetrate through cracks or holes in the outer sheathing into the insulation layer and reach the wall of the medium-carrying pipe. At a medium temperature exceeding 100°C, the insulation material (polyurethane foam) will boil away, and pressure will build up, causing moisture to spread along the length of the liquid pipeline and further degrade the insulation material. After the leak has been detected (due to a leak detection malfunction), repairs often take a long time to carry out, making replacement costs particularly high. A characteristic of such liquid pipelines is the formation of a space between the medium-carrying pipe and the insulation material. As a result of this space, groundwater ingress due to damage to the outer sheathing can spread along the length of the liquid pipeline. At a medium temperature of 100°C or higher, the groundwater in contact with the medium-carrying pipe will boil, boiling away the polyurethane foam. The boiling of the groundwater in the space between the sheathing pipe and the medium-carrying pipe creates a pressure buildup, causing the groundwater to move further along the medium-carrying pipe and / or seek an escape from the liquid pipeline. What remains is a weak, warm outer sheath draped over the medium-carrying pipe, and the lack of thermal insulation of the heat being transported from the surrounding environment. Groundwater containing boiled-off polyurethane foam that has escaped the outer casing will rise above the ground level / infrastructure as uncontrolled vapor / steam. This results in odor nuisance combined with visible vapor / steam formation.

[0007] When repairing the liquid pipeline, it is assumed that the liquid pipeline is damaged from bend to bend or from bend to T-piece and must be replaced.

[0008] Summary of the invention

[0009] An object of the invention is to provide a liquid pipeline with less damage in the event of damage to the outer casing than with the known liquid pipeline. To this end, the liquid pipeline according to the invention is characterized in that the baffle is liquid-tightly connected to the medium-carrying pipe along the entire circumference of the medium-carrying pipe, and is liquid-tightly connected to the outer casing along the entire circumference of the medium-carrying pipe. The baffle forms a water barrier, which, in the event of damage, limits the internal spread of penetrating groundwater along the length of the liquid pipeline. This means that when repairing a liquid pipeline, at most the section of the pipeline between two baffles on either side of the damage needs to be replaced.

[0010] US 2011 / 0214770 Al discloses an insulating element consisting of a closed, semicircular- arc -shaped housing containing insulating material that can be applied to a medium-carrying pipe to insulate it. This insulating element is not suitable for use with liquid pipelines where the insulating material is in direct contact with the medium-carrying pipe and an outer sheath surrounds the insulation material. An embodiment of the liquid pipeline according to the invention is characterized in that the baffle comprises an inner disc with a hole and threaded ends attached to it, as well as an outer disc with a hole and holes through which the threaded ends extend, a first annular seal between the two discs and between the discs and the outer casing, and a second annular seal between the two discs and between the discs and the medium-carrying pipe, with nuts threaded onto the threaded ends. This construction of the baffle ensures a liquid-tight connection between the baffle and the outer casing and the medium-carrying pipe, and allows for easy installation.

[0011] The first seal preferably comprises an HDPE ring with a rectangular cross-section, which is surrounded on both axial sides and the inside by an EPDM ring or silicone ring.

[0012] The second seal preferably comprises an EPDM ring or silicone ring that extends outward between the outer disc and the medium-carrying pipe, with a hose clamp around the protruding portion of the second seal. A further embodiment of the liquid pipeline according to the invention is characterized in that the baffle is formed by a cured layer of resin. The resin-formed baffle is bonded directly to the mediumcarrying pipe and the outer casing, so no additional sealing is required.

[0013] The invention also relates to a method for improving a liquid pipeline for underground liquid transport, which comprises an outer casing, a medium-carrying pipe within the outer casing, and insulation material between the medium-carrying pipe and the outer casing. The improvement involves modifying a liquid pipeline in such a way that, in the event of leakage in the outer casing, damage to the liquid pipeline is limited. Regarding this method, the invention is characterized in that the insulation material and the outer casing are removed from the liquid pipeline over a distance, after which a baffle is applied to the insulation material of one of the sections of the liquid pipeline adjacent to the interruption and is connected liquid-tightly to the medium-carrying pipe and to the outer casing of that section of the liquid pipeline. The baffle forms a water barrier that prevents groundwater seepage over a long length of the liquid pipeline in the event of a leak in the outer casing.

[0014] An embodiment of the method according to the invention is characterized in that the baffle is installed by placing two plate sections, each provided with a semicircular recess, over the exposed medium-carrying pipe and connecting them or bonding them together in a liquid-tight manner. In the case of a liquid pipeline already present in the ground, a plate with a hole can only be placed around the medium- carrying pipe after first interrupting the pipe. However, this is undesirable. With the method according to the invention, the liquid pipeline does not need to be interrupted to install the baffle.

[0015] A further embodiment of the method according to the invention is characterized in that the baffle is installed by applying a viscous resin over the entire side surface of the insulation material against the insulation material of one of the sections of the liquid pipeline adjacent to the interruption, thereby creating a liquid-tight connection to the medium-carrying pipe and the outer casing of that section of the liquid pipeline. The advantage of this method over the method described above is that the application of the resin also creates a liquid-tight connection to the medium-carrying pipe and the outer casing, without requiring any additional steps. This method also does not require interrupting the liquid pipeline to install the baffle.

[0016] Brief description of the drawings

[0017] The invention will be explained in more detail below using exemplary embodiments of the liquid pipeline according to the invention shown in the drawings. In the drawings:

[0018] Figure 1 shows a network of liquid pipelines during installation in the ground;

[0019] Figure 2 shows an end of a known liquid pipeline;

[0020] Figure 3 shows a first embodiment of the liquid pipeline according to the invention;

[0021] Figure 4 shows the baffle of the liquid pipeline shown in Figure 3;

[0022] Figure 5 shows a second embodiment of the liquid pipeline according to the invention;

[0023] Figure 6 shows a baffle for use in an existing liquid pipeline;

[0024] Figure 7 shows the liquid pipeline shown in Figure 3 with the baffle divided into separate parts;

[0025] Figure 8 shows a detail of the liquid pipeline with composite baffle shown in Figure 7 ;

[0026] Figure 9 shows a third embodiment of the liquid pipeline according to the invention in longitudinal section; and

[0027] Figure 10 shows the liquid pipeline shown in Figure 9 in front view. Detailed description of the drawings

[0028] Figure 1 shows a network of underground liquid pipelines 1 for district heating, through which hot water flows for heating homes and buildings. The network comprises interconnected straight and curved (bend) liquid pipelines 1. The connection between the liquid pipelines is established by welding the medium-carrying pipes together. The outer sheaths of the liquid pipelines are connected via a sleeve. This sleeve is welded to the outer sheaths by heating the inside of the sleeve by passing a high current through a resistance wire within the sleeve. The space between the insulation layers of the liquid pipelines is then filled with insulating material.

[0029] Figure 2 shows one end of a known liquid pipeline 1. This known liquid pipeline 1 has an outer sheath 3 and a medium-carrying pipe 5, which is located within the outer sheath 3 and extends from the outer sheath 3 at ends 3A. Insulating material 7 is present between the outer sheath 3 and the medium-carrying pipe 5. The mediumcarrying pipe 5 is often made of steel, and the outer sheath 3 is often made of polyethylene. Polyurethane foam is often used as the insulating material 7. Leak detection wires 8 extend through the insulating material 7.

[0030] Figure 3 shows one end of a first embodiment of the liquid pipeline 1A according to the invention. All components identical to the known liquid pipeline 1 shown in Figure 2 are designated with the same reference numerals. The liquid pipeline 1A is provided at one end with a baffle formed by a plate 9 that rests against the insulating material. This plate 9 is provided with a circular hole 11 and is slid over the medium-carrying pipe 5 until it touches the insulation material and the outer sheath 3. Hole 11 has a diameter equal to the outer diameter of the medium-carrying pipe 5. Plate 9 is connected liquid-tight to the medium-carrying pipe 5 over the entire circumference of the medium-carrying pipe 5 and is connected liquid-tight to the outer sheath 3 over the entire circumference of the outer sheath 3. Plate 9 is also provided with two (or in some cases four) small holes 13 through which the leak detection wires 8 extend liquid- tight. These small holes 13 are sealed liquid-tight after the leak detection wires 8 have been fed through the holes.

[0031] When connecting two liquid pipelines 1A, the baffle end of one of the liquid pipelines is attached to the non-baffle end of the other liquid pipeline. In the pipe network formed in this way, partitions are placed between the liquid pipelines, which liquid-tightly separate the spaces containing insulation material. This prevents incoming groundwater from moving internally to neighboring liquid pipelines in the event of a leak in the outer casing of a liquid pipeline.

[0032] Liquid pipeline 1A is constructed by inserting the medium-carrying pipe 5 into the outer casing 3 and filling the space between the medium-carrying pipe 5 and the outer casing 3 with insulation material 7. Then, at one end of liquid pipeline 1, plate 9 is slid over the protruding part of the medium-carrying pipe 5 and secured liquid- tightly to the outer casing 3 and the medium-carrying pipe 5, for example, with adhesive or sealant.

[0033] Plate 9 is shown separately in Figure 4. Plate 9 is formed by a circular disc with the circular hole 11 located in the center of the disc. The smaller holes 13 are both located in one half of the disc. In the case of four leak detection wires, there are also four smaller holes distributed across the disk.

[0034] The liquid pipeline can also be designed without leak detection wires and equipped with several medium-carrying tubes. As an example of another embodiment, one end of a second embodiment of the liquid pipeline according to the invention is shown in Figure 5. All components identical to the first embodiment of the liquid pipeline shown in Figure 3 are indicated with the same reference numerals. This liquid pipeline IB has two medium-carrying tubes 5; otherwise, this liquid pipeline is identical to the first embodiment.

[0035] Existing pipeline networks that are not equipped with water-retaining baffles can still be fitted with such baffles. Of course, access must first be granted to the liquid pipeline, and then the insulation material 7 and the outer sheathing 3 are removed along the entire circumference of the liquid pipeline, covering a portion of its length. Next, two plate sections 9A and 9B, each provided with a semicircular recess 11A, 1 IB, are placed over the exposed medium-carrying pipe 5 and against the insulation material 7 of one of the sections of the liquid pipeline adjacent to the interruption. These plate sections 9A and 9B are secured together in a liquid-tight manner, for example with sealant, and also secured in a liquid-tight manner to the medium-carrying pipe 5 and to the outer sheathing 3. The outer sheathing sections are then reconnected via a sleeve, and the space between the sections of the liquid pipeline is filled with insulation material. Figure 6 shows a plate for use in an existing liquid pipeline. This plate consists of two halves 9A and 9B, each provided with a semicircular recess 11A and 11B. Smaller holes 13 for the leak detection wires are located in one of the halves 9A.

[0036] Figure 7 shows the liquid pipeline 1 shown in Figure 3 with the baffle 9 in its separate components, and Figure 8 shows a detail of the liquid pipeline 1 shown in Figure 7 with an assembled baffle 9. Baffle 9 has a perforated steel inner disc 21 with threaded ends 23 attached to it and a perforated steel outer disc 25 with holes 27 through which the threaded ends 23 extend. Baffle 9 also has a first annular seal 29, which is located partly between the two discs 21 and 25 and partly between the discs 21 and 25 on one side and the outer casing 3 on the other. Baffle 9 also has a second annular seal 31 located between the two discs 21 and 25 and between the discs 21 and 25 on one side and the medium-carrying pipe 5 on the other. Nuts 33 are threaded onto the ends of the threaded end 23 to enclose the sealing rings 29 and 31.

[0037] The first seal 29 consists of an HDPE ring 35 with a rectangular crosssection and an EPDM or silicone ring 37 that surrounds both axial sides and the inside of the HDPE ring 35. The second seal 31 consists of an EPDM or silicone ring 39 that extends outward between the outer disc 25 and the medium-carrying pipe 5. A hose clamp 43 is provided around the protruding portion 41 of the second seal 31 to ensure an even better fit of the second seal 31 to the medium-carrying pipe 5.

[0038] Figures 9 and 10 show a third embodiment of the liquid pipeline according to the invention in longitudinal section and front view, respectively. All components identical to those of the previously described embodiments are indicated by the same reference numerals. In this embodiment, the baffle is formed by a layer of cured resin 10, which is applied in a viscous state to the side surface of the insulation material 7 during manufacturing, thereby adhering in a liquid-tight manner to the outside of the medium-carrying pipe 5 and to the inside of the outer casing 3.

[0039] Although the invention has been explained above with reference to the drawings, it should be noted that the invention is by no means limited to the embodiments shown in the drawings. The invention also extends to all embodiments deviating from the embodiments shown in the drawings, within the scope defined by the claims. The liquid pipeline according to the invention can also be used advantageously for transporting colder liquids, for example, if spaces in homes or business premises need to be cooled instead of heated. Here too, the insulation material is subjected to groundwater leakage in the outer sheathing, and the groundwater will spread along the length of the liquid pipeline through the insulation.

Claims

CLAIMS:

1. Liquid pipeline (1A; IB), in particular a liquid pipeline for underground transport of hot liquid, comprising an outer casing (3), a medium-carrying pipe (5), which is present in the outer casing (3) and protrudes with ends (3A) from the outer casing (3), and insulating material (7) present between the outer casing (3) and the medium-carrying pipe (5) and in contact with the inside of the outer casing (3) and the outside of the medium-carrying pipe (5), whereby at, at least one end of the liquid pipeline (1A; IB), a baffle is present against the insulating material (7), whereby the baffle is provided with a circular hole (11) and the medium-carrying pipe (5) protrudes through the hole (11), characterized in that the baffle is connected liquid-tightly to the medium-carrying pipe (5) over the entire circumference of the medium-carrying pipe (5) and to the outer casing (3) in a liquid-tight manner over the entire circumference of the outer casing (3).

2. Liquid pipeline (1A; IB) according to claim 1, characterized in that the baffle comprises an inner disc (21) with a hole and threaded ends (23) attached thereto, as well as an outer disc (25) with holes (27) through which the threaded ends (23) extend, a first annular seal (29) between the two discs (21, 25) and between the discs (21, 25) and the outer casing (3), and a second annular seal (31) between the two discs (21, 25) and between the discs (21, 25) and the medium-carrying pipe (5), with nuts (33) screwed onto the threaded ends (23).

3. Liquid pipeline (1A; IB) according to claim 2, characterized in that the first seal (29) comprises an HDPE ring (35) with a rectangular cross-section, surrounded on both axial sides and the inside by an EPDM ring or silicone ring (37).

4. Liquid pipeline (1A; IB) according to claim 2 or 3, characterized in that the second seal (31) comprises an EPDM ring or silicone ring (39) that extends outward between the outer disc (25) and the medium-carrying pipe (5), with a hose clamp (43) around the protruding portion (41) of the second seal (31).

5. Liquid pipeline (1A; IB) according to claim 1, characterized in that the baffle is formed by a cured layer of resin (10).

6. Method for improving a liquid pipeline (1A; IB) for underground transport of liquid, which liquid pipeline (1A; IB) comprises an outer casing (3), as well as a medium-carrying pipe (5) present in the outer casing (3) and insulating material (7) present between the medium-carrying pipe (5) and the outer casing (3), characterized inthat the insulating material (7) and the outer casing (3) are removed from the liquid pipeline over a distance, after which a baffle is fitted against the insulating material (7) of one of the parts of the liquid pipeline adjacent to the interruption and is connected in a liquid-tight manner to the medium-carrying pipe (5) and to the outer casing (3) of that part of the liquid pipeline.

7. Method according to claim 6, characterized in that the baffle is applied by placing two plate parts (9A, 9B), each provided with a semicircular recess (11 A, 1 IB), over the exposed medium-carrying pipe (5) and connecting or bonding them together in a liquid-tight manner.

8. Method according to claim 6, characterized in that the baffle is applied by applying a viscous resin (10) over the entire side surface of the insulation material (7) against the insulation material (7) of one of the sections of the liquid pipeline adjacent to the interruption, thereby connecting it in a liquid-tight manner to the medium-carrying pipe (5) and to the outer casing (3) of that section of the liquid pipeline.

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