METHOD FOR CONSTRUCTING A PIPE SECTION OF A PIPE SYSTEM AND A PIPE SECTION OF A PIPE SYSTEM IN A HEATING NETWORK

Description

[0001] The invention relates to a method for erecting a pipe section of a pipe system in a heating network, which is provided for the transmission of a heat transfer fluid between a heat supplier and at least one heat consumer, wherein a trench extending over the pipe section is excavated in the pipe section, wherein a pipe extending over the pipe section for transmitting the heat transfer fluid along the pipe section is introduced into the trench and embedded in a bedding material surrounding the pipe, and wherein the trench is subsequently refilled with a backfill material.

[0002] A district heating system typically comprises a heat supplier connected to one or more heat consumers via a district heating network. The heat supplier, for example a combined heat and power plant, generates heat from suitable energy sources and transfers it into a heat transfer fluid. While early district heating systems often used heated steam as the heat transfer fluid, most district heating systems currently in operation use heated water as the heat transfer fluid. The district heating network connects the heat supplier to one or more heat consumers, with the heat transfer fluid circulating in a closed pipe system of the district heating network and transferring heat from the heat supplier to the heat consumers. The district heat transferred from the heat supplier to the heat consumers is regularly used for a central thermal energy supply to several buildings.Such a district heating system can be operated in an energy-efficient, ecologically sound, and economically viable manner, provided that heat generation can be carried out efficiently in the central heat supplier, and the thermal energy introduced into the heat transfer fluid can be transferred to the individual heat consumers in the district heating network without excessive heat loss. Often, the heat supplier can also utilize otherwise barely usable thermal energy, such as waste heat from industrial production processes, to heat the heat transfer fluid.

[0003] A heating network, which connects a heat supplier with several heat consumers, is of great importance in this regard. A heating network can be a district heating network or a local heating network. With the help of a heating network, a heated heat transfer fluid or a cooled heat transfer fluid can be transferred from the heat supplier to one or more heat consumers. The following discussion primarily focuses on a district heating network and the transfer of heat energy using a heated heat transfer fluid, although this should not be understood as a limitation to a specific type of heating network or heat energy transfer. The construction of the heating network is often comparatively high, meaning that the heating network is a significant cost factor in the economic assessment of a heating system, and in particular a district heating system.To minimize heat energy loss during transmission from the central heat supplier to the various heat consumers, a heating network typically uses a thermally insulated underground pipe system. The pipe system in a pipeline section of the heating network is typically composed of individual pipe elements that are double-walled and feature the best and most efficient thermal insulation possible. Suitable double-walled pipe system elements typically comprise an inner carrier pipe and a jacket pipe concentrically surrounding the carrier pipe, with suitable thermal insulation arranged between the carrier pipe and the jacket pipe.The carrier pipe and the casing pipe are made of a suitable plastic material or metal, with the casing pipe providing mechanical protection against the typical stresses that can affect the individual pipe elements in a buried pipe system of a heating network. The thermal insulation can be, for example, a suitable plastic foam, although polyurethane foam is often used as thermal insulation.

[0004] The individual piping elements are typically complex composite pipes with correspondingly high manufacturing costs. The individual piping elements are manufactured as prefabricated bar stock and delivered to the excavated trench, where they are first embedded and then connected to each other. The individual piping elements must be connected to each other in a fluid-tight manner using complex installation and welding techniques to prevent unwanted leakage of the heat transfer fluid at the joints of the individual piping elements.

[0005] The high investment costs for constructing such a pipe system in a heating network are a major obstacle to the development and construction of decentralized renewable heat supply systems. A large portion of the investment costs are attributable to the manufacture and installation of the thermally insulated pipe elements.

[0006] It is therefore considered an object of the present invention to design a method for erecting a pipe section of a pipe system in a heating network in such a way that a pipe section can be manufactured as cost-effectively as possible and at the same time can be used cost-efficiently for transmitting district heating in a heating network with the lowest possible heat losses.

[0007] This object is achieved according to the invention in that in a segmentation step the pipeline section is divided into several segments, wherein for each segment a segment characteristic is determined on the basis of at least one soil physical characteristic and the determined segment characteristics of two adjacent segments differ by more than a predetermined segment characteristic difference value, and in that in a bedding determination step for each segment a segment embedding of a pipeline segment introduced into the trench in this segment in a water-permeable segment bedding material is predetermined such that within the segment a heat loss of the heat transfer fluid transferred in the pipeline segment, averaged over the segment and related to a unit of length, is less than a predetermined heat loss limit value.The invention is based on the finding that it is advantageous, both ecologically and economically, to construct the pipeline in the respective pipeline section from pipeline elements that can be manufactured and installed as cost-effectively as possible. Complex thermal insulation of the individual pipeline elements is not considered an essential measure, nor, in contrast to conventional heating networks, the only measure to minimize heat loss during the transfer of the heat transfer fluid through the respective pipeline section.Rather, it is taken into account that, due to the physical conditions of the soil in individual segments within the pipeline section, greater heat losses are to be expected from a pipeline element with only slight or even negligible thermal insulation, while in other segments, the soil surrounding the pipeline can promote and enhance the thermal insulation provided by the bedding material surrounding the pipeline. In many cases, a primary cause of undesirable heat transfer away from the pipeline is the soil water present in the soil. This leads to water movement in the soil surrounding the pipeline and also in the bedding material immediately surrounding the pipeline. This water movement leads to undesirable convective heat transfer away from the pipeline.

[0008] All materials are considered to be water-permeable within the meaning of the present invention if their permeability coefficient in the operating state of the heating network in the water-saturated state is greater than 1·10 -12< m / s.

[0009] Embedding the pipeline in a water-impermeable bedding material could significantly reduce or almost completely prevent heat loss due to convection of the groundwater, but is associated with considerable manufacturing costs and also places high demands on mechanical protection of the pipeline in the pipeline section, since the pipeline repeatedly expands and contracts due to thermal factors during its intended use.

[0010] In the segmentation step, the pipeline section can be divided into several segments, which preferably differ with regard to the hydraulic and thermal soil physical parameters, such as in particular the soil water saturation, the soil moisture content relationship, the permeability of the soil for fluids and in particular for liquids, or the heat capacity or thermal conductivity of the soil. After dividing the pipeline section into several segments, a suitable segment embedding for each segment can then be determined and specified in such a way that, with the help of a suitable segment bedding material, which is usually as low as possible in terms of water permeability, for the respective segment and depending on the soil physical conditions, a heat loss averaged across the segment is achieved that is as low as possible, which is in any case lower than a specified heat loss limit.The thermal insulation of the pipeline laid in the relevant pipeline section is therefore not achieved by using double-walled pipeline elements that are as thermally insulated as possible, but rather by the most clever selection of a segmental bedding material that can be produced as cost-effectively as possible, in which the pipeline element is embedded and which assumes the function of thermal insulation.

[0011] For example, the specified heat loss limit can correspond to the heat loss achievable with the currently conventionally used double-walled and thermally insulated pipeline elements. A suitable, water-permeable segmented bedding material can be, for example, sand mixed with suitable aggregates. The aggregates reduce the thermal conductivity of the bedding material and thus improve its thermal insulation properties. The segmented bedding material therefore not only acts as a mechanical protective sheath around the pipeline element laid in the trench, but also provides efficient thermal insulation of the pipeline element and reduces the heat loss of the heat transfer fluid conveyed in the pipeline section.

[0012] Depending on the segmental bedding material used in each individual case and in each individual segment, it may be possible or even advantageous to backfill the trench exclusively with the respective segmental bedding material, i.e., the backfill material must match the segmental bedding material. The use of different materials is not necessary. Instead, the trench may be completely backfilled with the segmental bedding material if, for example, the additional costs incurred for using different materials exceed the additional costs of the segmental bedding material compared to a different backfill material.

[0013] According to one embodiment of the inventive concept, the segmentation step involves dividing the pipeline section into several segments based on at least one soil-physical parameter describing the soil water balance. Such a soil-physical parameter describing the soil water balance can be, for example, the saturation of the soil with soil water, the permeability of the soil to seeping or rising soil water from the subsurface, or the suction tension-water content relationship, or the suction tension of the pore water in the soil. The heat loss caused by convection of moisture, and in particular of pore water, represents a significant portion of the total heat loss occurring during the transfer of the heat transfer fluid in the buried pipeline section.The soil physical parameters describing the soil water balance are considered to be particularly important parameters for the division of the pipeline section into individual segments and the specification of a suitable segment bedding material for the individual segments.

[0014] In order to reduce the effort required to procure and install the segment bedding material in the individual segments concerned, an advantageous embodiment provides for the segment bedding material of at least one segment to contain a portion of trench segment material excavated during the excavation of the trench within the relevant segment. Thus, a portion of the segment bedding material, for example, a fine-grained fraction of the trench segment material excavated during the excavation of the trench, can be provided on-site without the need to transport large quantities of material over long distances.The relevant portion of trench segment material can be processed and thermally conditioned using suitable additives in order to exert a sufficient thermal insulation effect on the pipeline element covered with the processed trench segment material when subsequently used as segment bedding material.

[0015] It is also conceivable that the segment bedding material is manufactured from a standardized bedding material that essentially meets the mechanical requirements for reliable embedding and low stress on the pipeline. This could, for example, be a suitable sand material that is already used for conventional embedding of pipelines in excavated trenches. The standardized bedding material can be thermally conditioned for each individual segment by adding or mixing in suitable aggregates, thus providing it with the thermal insulation properties required for the thermal insulation of the pipeline in that segment.

[0016] To enable the most cost-effective construction of the pipeline section, one embodiment of the inventive concept provides for the pipeline segment to be provided in at least one segment as a coiled product, unwound from a transport reel, and inserted into the excavated trench. By using pipeline segments that can be long, for example, 50m, 100m, or more than 250m long, and that can be rolled up onto a transport reel in a space-saving manner, transported, and kept ready on site, the manufacturing and processing costs of the pipeline can be significantly reduced. It is also possible for the pipeline segment unwound from the transport reel to be pulled into the trench, for example, using a pipe plough.By using comparatively long piping elements, the number of joints between adjacent piping elements is significantly reduced, resulting in less time-consuming and costly welding work for fluid-tight connection of adjacent piping elements.

[0017] Advantageously, it is optionally provided that a plastic pipe segment with a pipe heat loss per unit length is introduced into the excavated trench as the pipe segment, wherein the pipe heat loss is higher than the specified heat loss limit. In order not to exceed the specified heat loss limit, it is therefore necessary for the segment bedding material surrounding the pipe segment to make a significant and, if necessary, significant contribution to the thermal insulation of the pipe segment in the trench.If the pipeline heat loss is comparatively low and only slightly exceeds the specified heat loss limit, the segment bedding material surrounding the pipeline segment can have a comparatively low thermal insulation effect and can be manufactured comparatively inexpensively from conventional bedding materials such as fine-grained sand, or possibly also from coarse-grained trench material or earth material with a different consistency. However, if a plastic pipe segment with a comparatively high pipeline heat loss is used, the surrounding segment bedding material must make a large and possibly significant contribution to the thermal insulation of the pipeline segment in the trench and possess the necessary thermal insulation properties. For this purpose, the plastic pipe segment used can be designed very cost-effectively.In many cases, by appropriately selecting and specifying the plastic pipe segment in conjunction with the surrounding segment bedding material, it is possible to ensure that the individual components can be manufactured very cost-effectively and used for the construction of the pipeline segment in the segment in question.

[0018] According to a particularly advantageous embodiment of the inventive concept, it is provided that the pipeline segment is not a double-walled pipe, but a single-walled pipe, preferably a single-walled pipe made of polyethylene, which is inserted into the excavated trench. A single-walled polyethylene pipe that is not surrounded by additional heat-insulating foam or the like can be manufactured particularly cost-effectively and transported to the trench in coils and embedded therein. Single-walled polyethylene pipes are commercially available in various diameters and wall thicknesses and are therefore very inexpensive. Various installation methods are known for inserting a single-walled plastic pipe into an excavated trench, which can be carried out relatively quickly and inexpensively.A polyethylene pipeline segment has a high resistance to the temperatures and temperature gradients occurring in a district heating network as well as to the mechanical stresses during installation and subsequent changing district heat transport in the ground.

[0019] By using single-walled polyethylene plastic pipes in combination with a suitable segmented bedding material that surrounds the pipe segment and reduces heat loss within the pipe segment to below a specified heat loss limit, a significant reduction in the costs incurred for the construction of the pipe section within the heating network is possible compared to a conventional construction of a comparable pipe section with double-walled and thermally insulated pipe elements. Estimates suggest that a very significant reduction in the total costs incurred for the construction of the pipe section is possible.

[0020] The invention also relates to a pipe section of a pipe system in a heating network, which is provided for transmitting a heat transfer fluid between a heat supplier and at least one heat consumer. In the pipe section, a pipe extending over the pipe section for transmitting the heat transfer fluid is arranged together with a bedding material surrounding the pipe in a lower region of a trench, which is filled with a backfill material in an upper region. For example, EP 3 165 831 A1 describes a pipe system of a heating network. In conventional pipe sections of a heating network, the pipe extending over the pipe section is usually of uniform design and composed of a large number of double-walled and thermally insulated rod-shaped pipe elements.The individual pipeline elements must be suitably inserted into the excavated trench and then connected to each other in a fluid-tight manner. The installation effort required for this is comparatively extensive and results in high investment costs for the construction of the pipeline section.

[0021] DE 102 02 186 A1 discloses an arrangement for buried tubular supply lines, in which spaced-apart hose bodies filled with a first backfill material are arranged beneath or around a pipe section, thereby securing the pipe section, while the trench areas between the hose bodies are filled with a different backfill material. The hose bodies and the associated different backfill materials are intended to promote and enable the most stress-free and extensive support of a pipe section within the subsequently introduced backfill material. The impact on heat losses within the pipe section is not taken into account.

[0022] Furthermore, EP 1 319 898 B1 discloses a pipeline laid underground for a district heating system, which comprises pipes embedded in a sand-filled pipe zone of a pipe trench. In order to enable a reduction in heat losses, it is proposed that at least 50% by weight of the sand filling of the pipe zone consist of fired clay. It is therefore also considered an object of the present invention to design a pipe section of the aforementioned type in such a way that the pipe section can be manufactured as cost-effectively as possible and yet a predetermined heat loss limit is not exceeded during the transfer of the heat transfer fluid through the pipe section. This object is achieved according to the invention in that the pipe section is divided into several segments,wherein a segment characteristic determined for each segment on the basis of at least one soil physical characteristic of two adjacent segments differs by more than a predetermined segment characteristic difference value, that a first segment embedding of a first pipeline segment introduced into the trench in a first segment in a first water-permeable segment bedding material differs from a second segment embedding of a second pipeline segment introduced into the trench in a second segment in a second water-permeable segment bedding material, and that in the case of a soil within a segment for which the determined segment characteristic already has advantageous and possibly almost sufficient thermal insulation properties,only a small expenditure is required for a suitable segment bedding material and the segment bedding material used has lower thermal insulation properties than in a segment with soil surrounding the pipeline segment, which, in terms of its physical soil properties, is not very suitable for providing sufficient thermal insulation for the pipeline segment laid therein, in which a suitable segment bedding material with sufficiently high thermal insulation properties is used.

[0023] The typically high investment costs for constructing a pipeline section within a heating network can be significantly reduced by appropriately dividing the pipeline section into several segments and using a segment bedding material tailored to the respective segment and provided at low cost. Using a water-permeable segment bedding material can avoid the costly provision and time-consuming embedding of the pipeline segment in a water-impermeable bedding material.The thermal insulation properties of the water-permeable segment bedding material used within a segment are adapted to the physical properties of the surrounding soil within each segment in such a way that the water-permeable segment bedding material provides sufficient thermal insulation for the use of the pipe segment within a heating network and that excessive heat loss during the passage of a heated heat transfer fluid can be avoided even with reduced or insignificant separate thermal insulation of the pipe segment.The segment bedding material used in each case can be adapted to the respective segment with regard to its various properties and can be specified in such a way that, in addition to the mechanical properties required for embedding the pipeline segment, the thermal and hydraulic properties of the segment bedding material required for thermal insulation are also advantageously adapted or the relevant requirements are met.

[0024] For example, effective thermal conductivity, a suction tension-water content function (pF curve), fluid permeability, and heat capacity are considered particularly relevant thermal and hydraulic parameters for the water-permeable segmented bedding material. With regard to mechanical properties, compaction, solubility, strength, dimensional stability, and, if applicable, rheology are considered important mechanical parameters for the water-permeable segmented bedding material used in each individual case. With a view to ensuring the particularly economical and ecological suitability of the heating network constructed in this way, additional properties such as durability, environmental performance, and recyclability of the pipeline segment and the surrounding segmented bedding material can be considered and advantageously specified or adapted.

[0025] In contrast to conventional heating networks, in which a buried pipeline section essentially consists of a single, thermally insulated pipeline laid in a uniformly specified bedding material, by dividing the pipeline section into different segments, the respective soil physical conditions in the individual segments can be advantageously utilized and used to reduce the manufacturing costs for a thermally insulating segmental bedding material and thus for sufficient thermal insulation within the segment. If the soil within a segment already has advantageous and possibly almost sufficient thermal insulation properties, only a minimal effort is required for a suitable segmental bedding material.If, however, the surrounding soil is not suitable in terms of its physical properties to provide sufficient thermal insulation for a pipeline segment laid therein, this thermal insulation function can be taken over and provided by a segment bedding material adapted to it and with sufficiently high thermal insulation properties.

[0026] In order to reduce the often complex and costly transport of segment bedding material from a distant production site to the excavated trench and thus to the site of use for the production or provision of the segment bedding material, it is optionally provided that the segment bedding material of at least one segment contains a proportion of trench segment material that was excavated within the respective segment during the excavation of the trench. The segment bedding material can, for example, be produced on site from a reprocessed fraction of the excavated trench segment material by adding additional aggregates and, if necessary, additional compaction of the segment bedding material introduced into the trench.By using excavated trench material on site, the transport volume and weight of the segment bedding material components that would otherwise need to be transported to the pipeline segment's installation site or to the excavated trench can be significantly reduced. Furthermore, the disposal costs associated with the otherwise necessary disposal of the excavated trench material can be reduced.

[0027] According to a particularly advantageous embodiment of the inventive concept, the pipeline segment has at least one pipeline element with a length of more than 20 meters, preferably more than 100 meters, and particularly preferably more than 250 meters, in at least one segment. The individual pipeline element with such a long length is preferably manufactured as a coiled product and is transported on a transport roller to the trench or to the installation site, where it is prepared on the transport roller for installation and insertion into the trench. Due to the great length of the individual pipeline elements, there are significantly fewer joints between adjacent pipeline elements in the entire pipeline section, which must be connected to one another in a fluid-tight manner using usually complex welding processes.This allows the manufacturing costs for a pipeline section designed in this way to be further reduced.

[0028] In order to also save costs during the production of the pipeline segment laid within a segment, one embodiment of the inventive concept provides for the pipeline segment to comprise a plastic pipe segment with a pipeline heat loss per unit length that is higher than the specified heat loss limit. Preferably, the pipeline segment comprises a single-walled plastic pipeline element, particularly preferably a single-walled plastic pipeline element made of polyethylene. Such plastic pipes, and in particular single-walled plastic pipeline elements made of polyethylene, are commercially available and very cost-effective.The cost savings possible for the procurement and installation of such inexpensive plastic piping elements significantly exceed the additional costs required for the individual adaptation and provision of the segment bedding material in the individual segments.

[0029] In this way, a heating network composed of multiple pipeline sections can be constructed at significantly lower cost than conventionally designed heating networks. By appropriately adapting the segment bedding material in the individual segments, which are specified depending on the physical soil conditions along the pipeline section, sufficient thermal insulation can be achieved even when using pipeline segments with little or no thermal insulation, and heat loss of the heat transfer fluid transferred in the pipeline segments can be achieved below a predetermined heat loss limit. Thus, a heating network according to the invention can be used and operated with comparable operating parameters and, in particular, with comparable operating costs to a conventionally constructed heating network.In individual cases, it may also be an economically sensible decision to deliberately accept a comparatively high heat loss in one segment if this can avoid significantly higher manufacturing costs for the relevant pipeline section.

[0030] Below, some embodiments of the inventive concept are explained in more detail, as shown in the drawing. It shows: Figure 1 a schematic representation of a district heating system with a heat supplier and several heat consumers, whereby a heat transfer fluid can be transferred from the heat supplier to the heat consumers via a heat network and returned to the heat supplier after heat extraction at the individual heat consumers, Figure 2a schematic representation of a pipeline section within the heating network, wherein the pipeline section is divided into several segments, with adjacent segments differing by the physical properties of the soil surrounding the pipeline section, Figure 3 a sectional view of a pipeline segment laid in a trench and embedded in a surrounding segment bedding material along a line III - III in Figure 2 , and Figure 4 a sectional view along a line IV - IV in Figure 2 of an adjacent segment with a pipeline segment laid in a trench and covered by a different segment bedding material than in Figure 3 shown surrounded.

[0031] In Figure 1A district heating system 1 is shown schematically for supplying several heat consumers 2 with thermal energy generated by a heat supplier 3. The heat supplier 3 can, for example, be a combined heat and power plant or a waste incineration plant or other industrial facility in which usable waste heat is generated and can be used to heat a heat transfer fluid. The heat transfer fluid impinged with thermal energy is transferred from the heat supplier 3 via a heating network 4 to the individual heat consumers 2 and, after each heat consumer 2 has individually removed thermal energy, is returned to the heat supplier 3, thus forming a circuit for the heat transfer fluid.

[0032] The heating network 4 comprises several pipeline sections 5, 6, 7. The individual pipeline sections 5, 6, 7 of the heating network 4 can be subdivided or assigned to a transport network typically connected to the heat supplier 3, to a subsequent distribution network, and to individual heat consumer connections from the distribution network. A division of the respective pipeline sections 5, 6 into individual segments according to the invention is particularly suitable for pipeline sections 5, 6 within the transport network and the distribution network.

[0033] In Figure 21 schematically shows a pipeline section 6 within the distribution network of the heating network 4, wherein the pipeline section 6 has two parallel pipelines for the supply and return of the heat transfer fluid. Preliminary investigations have determined soil physical parameters for the surrounding soil. On the basis of the soil physical parameters, such as a soil tension-water content relationship or a permeability for fluids, the pipeline section 6 is divided into several segments A, B, C, D and E in a segmentation step. For each segment A to E, a segment parameter is determined based on at least one of the determined soil physical parameters, and the determined segment parameters of two adjacent segments A to E differ by more than a predetermined segment size difference value.In this way, the pipeline section 6 is divided into several segments A to E, in which approximately uniform soil physical properties of the surrounding soil are present within the respective segments A to E, while the soil physical properties of the surrounding soil of two adjacent segments A to E differ sufficiently significantly, or by more than a predetermined segment size difference value.

[0034] The length of the individual segments A to E can vary depending on the surrounding soil along the pipeline section 6. It has been shown that, with regard to cost-effective construction of the pipeline section 6, advantageous lengths of the individual segments A to E can vary between less than 50 meters or 100 meters on the one hand and possibly several kilometers on the other.

[0035] For each segment A to E, a water-permeable segment bedding material is specified in a bedding determination step such that within the segment A to E, a heat loss of the heat transfer fluid transferred in a pipe segment 8, 9, 10, 11, 12 laid in the respective segments A to E, averaged over the segment A to E and related to a unit of length, is less than a specified heat loss limit value.

[0036] In the Figures 3 and 4 are two exemplary sectional views along the Figure 2 shown in the figure. For the installation of the pipes in the Figures 3 and 4 For the exemplary pipeline segments 9, 10, a trench 15 is first excavated from the ground 13, 14. In the trench 15, the Figure 3The pipeline segment 9 is inserted into the schematically shown segment B and surrounded by a segment bedding material 16 adapted to the segment B. In the same way, in the Figure 4 In the segment C shown, the relevant pipeline segment 10 is embedded in a segment bedding material 17 adapted to the segment C, whereby this segment bedding material 17 differs from the segment bedding material 16 introduced into segment B with regard to its thermal and hydrological properties. Subsequently, the remaining trench areas 18 not filled with the respective segment bedding material 16, 17 are refilled with the previously excavated soil 13, 14.

[0037] The pipeline segments 8, 9, 10, 11, and 12 laid within segments A to E are each single-walled plastic pipeline elements made of polyethylene, which have only low thermal insulation properties for a heat transfer fluid circulating through the respective pipeline segments 8, 9, 10, 11, and 12. The heat loss is therefore primarily caused by the segment bedding material 16, 17 surrounding the pipeline segments 8, 9, 10, 11, and 12.For this purpose, the segment bedding material 16, 17 used in the respective segments A to E is adapted to the soil physical properties of the surrounding soil 13, 14 in order to achieve the best possible thermal insulation and thus the lowest possible heat loss for the heat transfer fluid transferred through the pipe segments 8, 9, 10, 11, 12 in the pipe section 6 with the lowest possible manufacturing effort for the segment bedding material 16, 17 in question.

Claims

1. Method for constructing a pipeline portion (5, 6, 7) of a pipe system in a heating network (4) which is provided for transferring a heat transfer fluid between a heat supplier (3) and at least one heat consumer (2), wherein a trench (15) extending over the pipeline portion (5, 6, 7) is excavated in the pipeline portion (5, 6, 7), wherein a pipeline extending over the pipeline portion (5, 6, 7) for transferring the heat transfer fluid along the pipeline portion (5, 6, 7) is introduced into the trench (15) and is embedded in a bedding material surrounding the pipeline, and wherein the trench (15) is then backfilled with a backfill material again, characterised in that, in a segmentation step, the pipeline portion (5, 6, 7) is divided into a plurality of segments (A, B, C, D, E), wherein a characteristic segment variable is determined for each segment (A, B, C, D, E) based on at least one physical characteristic soil variable and the determined characteristic segment variables of two adjacent segments (A, B, C, D, E) differ by more than a predefined characteristic segment variable difference value, in that a segment embedding of a pipeline segment (8, 9, 10, 11, 12) introduced into the trench (15) in this segment (A, B, C, D, E) in a water-permeable segment bedding material (16, 17) is predefined in a bedding determination step for each segment (A, B, C, D, E) such that, within the segment (A, B, C, D, E), a length-unit-related heat loss, averaged over the segment (A, B, C, D, E), of the heat transfer fluid transferred in the pipeline segment (8, 9, 10, 11, 12) is less than a predefined heat loss limit value.

2. Method according to claim 1, characterised in that in the segmentation step, the pipeline portion (5, 6, 7) is divided into a plurality of segments (A, B, C, D, E) based on at least one physical characteristic soil variable describing the ground water balance.

3. Method according to claim 1 or claim 2, characterised in that the segment bedding material of at least one segment (A, B, C, D, E) comprises a portion of trench segment material which was excavated within the segment (A, B, C, D, E) in question during the excavation of the trench (15).

4. Method according to any of the preceding claims, characterised in that the pipeline segment (8, 9, 10, 11, 12) is provided in at least one segment (A, B, C, D, E) as a coiled bundle and is unwound from a transport reel and introduced into the excavated trench (15).

5. Method according to any of the preceding claims, characterised in that a plastics pipe segment having a length-unit-related pipeline heat loss is introduced into the excavated trench (15) as a pipeline segment (8, 9, 10, 11, 12), wherein the pipeline heat loss is greater than the predefined heat loss limit value.

6. Method according to any of the preceding claims, characterised in that the pipeline segment (8, 9, 10, 11, 12) which is introduced into the excavated trench (15) is not a double-walled pipe but a single-walled pipe, preferably a single-walled pipe made of polyethylene.

7. Pipeline portion (5, 6, 7) of a pipe system in a heating network (4) which is provided for transferring a heat transfer fluid between a heat supplier (3) and at least one heat consumer (4), wherein a pipeline extending over the pipeline portion (5, 6, 7) for transferring the heat transfer fluid is arranged in the pipeline portion (5, 6, 7) together with a bedding material surrounding the pipeline in a lower region of a trench (15), which is backfilled with a backfill material in an upper region (18), wherein the pipeline portion (5, 6, 7) is divided into a plurality of segments (A, B, C, D, E), wherein a characteristic segment variable, determined for each segment (A, B, C, D, E) based on at least one physical characteristic soil variable, of two adjacent segments (A, B, C, D, E) differs by more than a predefined characteristic segment variable difference value, and wherein a first segment embedding of a first pipeline segment (8, 9, 10, 11, 12), introduced into the trench (15) in a first segment (A, B, C, D, E), in a first water-permeable segment bedding material (16, 17) differs from a second segment embedding of a second pipeline segment (8, 9, 10, 11, 12), introduced into the trench (15) in a second segment (A, B, C, D, E), in a second water-permeable segment bedding material (16, 17), characterised in that, in ground within a segment (A, B, C, D, E) for which the determined characteristic segment variable already has advantageous and potentially almost sufficient thermal insulation properties, only a low amount of outlay is required for a segment bedding material (16, 17) adjusted thereto and the segment bedding material (16, 17) used has lower thermal insulation properties than in a segment (A, B, C, D, E) having ground surrounding the pipeline segment (8, 9, 10, 11, 12) that is less suitable in terms of its physical soil properties, in order to provide sufficient thermal insulation for the pipeline segment (8, 9, 10, 11, 12) laid therein in which a segment bedding material (16, 17) adjusted thereto having sufficiently high thermal insulation properties is used.

8. Pipeline portion (5, 6, 7) according to claim 7, characterised in that at least one segment bedding material (16, 17) comprises a portion of trench segment material which was excavated within the segment (A, B, C, D, E) in question during the excavation of the trench (15).

9. Pipeline portion (5, 6, 7) according to claim 7 or claim 8, characterised in that the pipeline segment (8, 9, 10, 11, 12) has, in at least one segment (A, B, C, D, E), at least one pipeline element having a length of greater than 20 metres, preferably greater than 100 metres, and particularly preferably greater than 250 metres.

10. Pipeline portion (5, 6, 7) according to any of claims 7 to 9, characterised in that the pipeline segment (8, 9, 10, 11, 12) comprises a plastics pipe segment having a length-unit-related pipeline heat loss that is greater than the predefined heat loss limit value.

11. Pipeline portion (5, 6, 7) according to any of claims 7 to 10, characterised in that the pipeline segment (8, 9, 10, 11, 12) is a single-walled plastics pipeline element, preferably a single-walled plastics pipeline element made of polyethylene.