CN101975324A - Method for electric preheating construction of directly-buried pipeline - Google Patents
Method for electric preheating construction of directly-buried pipeline Download PDFInfo
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- CN101975324A CN101975324A CN 200910243296 CN200910243296A CN101975324A CN 101975324 A CN101975324 A CN 101975324A CN 200910243296 CN200910243296 CN 200910243296 CN 200910243296 A CN200910243296 A CN 200910243296A CN 101975324 A CN101975324 A CN 101975324A
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Abstract
The invention relates to a method for electric preheating construction of a directly-buried pipeline, which comprises the following steps of: putting the pipeline and pipe components into a ditch groove; backfilling sandy soil into the ditch groove provided with a preheated section pipeline, wherein a specified distance is reserved between the backfilled sandy soil and two ends of the preheated section pipeline; sealing two ends of the preheated section pipeline; connecting the two ends of the preheated section pipeline to at least one cable respectively, wherein the cable is connected with a power supply device; arranging a pipeline elongation detector on the preheated section pipeline; arranging a temperature sensor at one end of the preheated section pipeline; when the preheated section pipeline is electrified, at least recording an initial temperature displayed by the temperature sensor and the initial position of the elongation detector; and after the preheated section pipeline is detected to reach a specified temperature and specified elongation, dismounting a preheating device on the preheated section pipeline, and backfilling and compacting the whole ditch groove. The construction method is simple, has low heat consumption and uniform preheating, shortens the construction period, and greatly improves the production efficiency.
Description
Technical field
The invention relates to a kind of method of construction of directly buried pipeline, especially a kind of in the piping erection process to the pipeline preheating insulation of switching on, the directly buried pipeline electric preheating that can fully discharge the pipeline thermal stress is executed the formula method.
Background technique
Along with the development of society, to produce and the improving constantly of living standard, the scope of central heat supply is also in continuous increase, so the also rising year by year of the auxilliary amount of establishing of heat supply pipeline.Owing to carry high-temp liquid in the heat supply pipeline, therefore the temperature stress of pipeline depends on the expand with heat and contract with cold size of distortion and the releasing degree of distortion that temperature variation produces, be the influence of variation of temperature in reducing to use to the extending amount of pipeline, pipeline is auxilliary to carry out heat treated to pipeline when establishing usually carrying out, discharge ducted stress, to avoid, guarantee the stability of operation because of variation of temperature causes pipeline destroyed.
At present, application mainly contains two kinds to the method that pipeline carries out The pre-heat treatment in centralized heating project, and a kind of is water preheat, and another kind is the wind preheating.
Directly buried pipeline is carried out water preheat to be handled, be to utilize water-heating boiler that ducted water is heated, the heat energy that utilizes hot water is heated to the process of uniform temperature with steel pipe, and direct-burried prefabricated thermal insulation heat supply pipeline is carried out water preheat, pipeline is freely extended, eliminate in the pipeline residual stress is installed.Its method is, before carrying out water preheat, elder generation's backfill sandy soil are pushed down pipeline, pipeline is connected with water-heating boiler, hot water is circulated between pipeline and water-heating boiler, pipeline is carried out preheating, when the pipeline elongation reaches or during near theoretical elongation, uses one-off compensator to connect closed conduct.When pipeline carried out preheating work at logical hot water, along with the rising of temperature, the pipeline tensile stress reduced gradually, and when reaching preheating temperature, integrated piping stress under this temperature is zero; Continue to heat up, the pressure stress of pipeline produces, and increases gradually along with the rising of temperature, and when temperature was raised to operating temperature, the pressure of pipeline was still less than the allowable stress of pipeline.
Directly buried pipeline is carried out the wind The pre-heat treatment, is to utilize heating blower that the air of heating is blown into the inside of pipeline, utilizes hot blast that the temperature of steel pipe is heated to certain temperature.Disclose a kind of " heating direct-burying pipeline hot-air pre-heating method and used air heating device " as " 03144267.6 " number Chinese patent, this method is that direct-burried prefabricated thermal insulation heat supply pipeline is carried out hot-air pre-heating, pipeline is freely extended, eliminate in the pipeline residual stress is installed; When the pipeline elongation reaches or during near theoretical elongation, the backfill sandy soil are pushed down pipeline; With the pipeline cooling, and between each preheating section, connect sealing with one-off compensator; When the logical thermal technology of pipeline did, along with the rising of temperature, the pipeline tensile stress reduced gradually, and when reaching preheating temperature, integrated piping stress under this temperature is zero; Continue to heat up, the pressure stress of pipeline produces, and increases gradually along with the rising of temperature, and when temperature was raised to operating temperature, the pressure of pipeline was still less than the allowable stress of pipeline.
There is following some shortcomings part in above-mentioned two kinds of known pre-heating means in work progress:
Establish in the work progress of pipeline auxilliary, adopt the method for water preheat that pipeline is carried out The pre-heat treatment, because pipe interior must have the medium of heating, therefore cause heat transfer efficiency low, energy consumption is big; When pipeline is carried out water preheat, need in pipeline, inject a large amount of high-temperature-hot-waters, therefore to the water in the pipeline be heated with water-heating boiler, and this heating plant is bulky, need to occupy bigger place at the construction field (site), enlarged the shared zone of construction, will road, the life in the big zone of periphery have been impacted for construction in modern city especially; In addition, the water preheat time is long, and utilizing water preheat that the temperature of steel pipe is raised to the design preheating temperature time generally needs week age; In the water preheat process, pipe interior has a large amount of hot water, because the weight of water has strengthened frictional force, generally all need the earthing preheating, soil can absorb certain heat and causes heating time long in the earthing warm, and heating-up temperature is inhomogeneous, and the unsettled situation of the elongation of pipeline occurs; And utilize the water preheat pipeline must install one-off compensator and valve additional on pipeline, the construction process complexity has increased construction cost simultaneously.
And establish in the work progress of pipeline auxilliary, adopt the method for wind preheating that pipeline is carried out The pre-heat treatment, need major and minor two groups of heating equipments to be respectively confession, water return pipeline hot wind supply, two groups of feeder apparatus have included direct-combustion hot air machine, circulating fan, mixing box, connecting pipe, temperature demonstration and control box, therefore confession, water return pipeline are being carried out in the process of The pre-heat treatment, need two cover wind preheating heating equipments, equipment needed thereby is more; Sealing is a key issue in the wind warm, is difficult to accomplish in the wind warm to being preheated the sealing fully of segment pipe at present, causes the hot blast heat radiation bigger, and steel pipe heats inhomogeneous in heating process, is prone to the unsettled phenomenon of elongation; In addition, because sealing difficulty is big during the wind preheating, can't seal completely pipeline during construction, therefore the temperature of steel pipe being raised to the design preheating temperature time needs five days usually, causes the wind preheating long heating time.
Therefore, the preheating cost height of present known water preheat, wind pre-heating mean, the site operation difficulty is big, the seal request of equipment and pipeline is than higher, because equipment volume is big, the carrying of equipment is cumbersome, and the construction area area is big, can not satisfy the construction requirement that improves constantly.
Summary of the invention
The object of the present invention is to provide a kind of defective that can overcome the prior art existence, reach energy-saving and cost-reducing, improve the directly buried pipeline electric preheating method of construction of efficiency of construction purpose, this method is specially adapted in being preheated segment pipe the pre-heat construction with pipe parts such as reducing, compensator, threeway, valves.
For this reason, the directly buried pipeline electric preheating method of construction that the present invention proposes comprises: the excavation groove, pipeline is put into described groove; Backfill sandy soil in being provided with the groove that is preheated segment pipe make the sandy soil of this backfill apart from the two end part that are preheated segment pipe one predetermined distance be arranged; The two end part that are preheated segment pipe are hermetically enclosed, to prevent that managing interior hot gas scatters and disappears; The described two end part that are preheated segment pipe are connected with at least one elastic cable paper respectively, and described elastic cable paper connects power supply unit, form the loop of a sealing; Near the end that is preheated segment pipe pipeline elongation detection device is being set; At an end that is preheated segment pipe temperature transducer is set, to adjust described current in loop amount at any time; Before being preheated the segment pipe energising, to write down the initial temperature of temperature transducer demonstration and the initial position of elongation detection device at least; Described after testing be preheated the temperature and elongation that segment pipe reaches regulation after, and whole groove carried out backfill and compacting; After trench backfill is finished, cut off system power supply, remove and be preheated the preheating device that is provided with on the segment pipe.
Aforesaid directly buried pipeline electric preheating method of construction wherein, is welded at least one bolt at the described two end part that are preheated segment pipe, and described elastic cable paper is connected with described bolt; When being welded with a plurality of bolt at the described two ends that are preheated segment pipe, interval 100mm between each bolt, each bolt and an elastic cable paper are fixedly connected; And the distance of the described pipe end of described bolt distance is more than or equal to 30mm.
Aforesaid directly buried pipeline electric preheating method of construction, wherein, described being preheated when having bigger pipeline of diameter and small diameter pipeline in the segment pipe carried out segmentation at the reducing place, makes the reducing place be positioned at the starting point or the end of preheating section.
Aforesaid directly buried pipeline electric preheating method of construction, wherein, described being preheated when having bigger pipeline of diameter and small diameter pipeline in the segment pipe, in each both sides, reducing place temperature transducer is set, in real time the temperature of reducing place both sides pipeline is measured, and the preheating temperature that the pipeline of different-diameter is calculated warming velocity respectively and finally reaches.
Aforesaid directly buried pipeline electric preheating method of construction, wherein, an end that is connected the bigger pipeline of reducing one side diameter is connected with power supply unit by elastic cable paper, the end that is connected the small diameter pipeline of reducing opposite side is connected in series by the short-circuiting cable line; When the temperature of small diameter pipeline and elongation reach preheating requirement, stop heating to this section of tubing; The short-circuiting cable line that connects small diameter pipeline is removed, and this short-circuiting cable line is connected to the other end of the bigger pipeline of the described diameter that is connected with described reducing, make the loop that forms a sealing between bigger pipeline of this diameter and the power supply unit, continuation is carried out preheating to the bigger pipeline of this diameter, and the groove that small diameter pipeline is set is carried out backfill.
Aforesaid directly buried pipeline electric preheating method of construction, wherein, the distance of the described reducing of the joint of the pipeline the other end that described short-circuiting cable line and described diameter are bigger distance is greater than 200mm.
Aforesaid directly buried pipeline electric preheating method of construction, wherein, described when being preheated the valve that has compensator in the segment pipe or be connected by flange, on the described pipeline that is connected in described valve or compensator both sides, bolt is set, and the bolt that is provided with on the described pipeline with jump leads and described valve or compensator both sides is connected, and makes the temperature rise that electric current caused passed through in described valve, the compensator heat resisting temperature less than valve or compensator inner seal liner.
Aforesaid directly buried pipeline electric preheating method of construction, wherein, the described segment pipe that is preheated comprises water supply line and water return pipeline, is connected in series by the short-circuiting cable line between described water supply, the water return pipeline.
Aforesaid directly buried pipeline electric preheating method of construction wherein, is installed two length check devices at least on the described the longest straight length that is preheated segment pipe, calculate the conformity of elongation and theoretical elongation with checking; And the described two end part that are preheated segment pipe are sealed by covering plastic end cap.
Aforesaid directly buried pipeline electric preheating method of construction wherein, before the beginning preheating, is backfilled to 3/4 place highly that sandy soil height in the described groove will reach described outer diameter tube, and tamps; Continue then to be backfilled to and exceed described outer diameter tube 50mm, must not tamp; And the sandy soil of this backfill are about 12 meters apart from the distance that is preheated the two end part of segment pipe, described pipeline elongation detection device is arranged on apart from the about 2 meters position, end that is preheated segment pipe, and described temperature transducer is arranged on apart from about 11 meters-12 meters position, end that is preheated segment pipe; In to the described heating process that is preheated segment pipe, the length change amount of the measured pipeline of the shown temperature value of described temperature transducer and elongation detection device is carried out three times at least measure.
Characteristics and the advantage of comparing directly buried pipeline electric preheating method of construction of the present invention with known technology are:
The directly buried pipeline electric preheating method of construction that the present invention proposes is connected with power supply unit by being preheated segment pipe, constitute a closed-loop path, the section of being preheated pipeline section is applied the electric energy of low voltage, high electric current, utilize the principle of pipeline (steel pipe) self-resistance heating, the temperature of steel pipe is heated to the design preheating temperature.This method of construction is simple, and with known wind preheating, that water preheat is compared thermal losses is little, preheating is even, and required preheat time is short, has shortened construction period, has improved manufacturing efficiency greatly.
In addition, the present invention adopts the low voltage of 20-56V to carry out The pre-heat treatment, has guaranteed construction safety effectively.
Directly buried pipeline electric preheating method of construction of the present invention is compared with known water preheat, wind pre-heating mean, and pre-heating device is simple, volume is little, in light weight, and easy operating, shockproof, noise free.And applied widely, as long as steel pipe is the medium transport pipe, can realize.
Description of drawings
The following drawings only is intended to the present invention done and schematically illustrates and explain, not delimit the scope of the invention.Wherein,
Fig. 1 is the trench cross-section schematic representation that is provided with pipeline in the directly buried pipeline electric preheating method of construction of the present invention, has schematically shown each sandy soil layer of backfill;
Fig. 2 is the annexation schematic representation of directly buried pipeline electric preheating method of construction of the present invention;
Fig. 3 is the distolateral portion's schematic representation of looking of pipeline in the directly buried pipeline electric preheating method of construction of the present invention, has schematically shown the position that is provided with of bolt;
Fig. 4 is that the pipe end master looks schematic representation in the directly buried pipeline electric preheating method of construction of the present invention, schematically shown bolt and on pipe lengths the position has been set;
Fig. 5 is preheating step one schematic representation that has tapered pipeline in the directly buried pipeline electric preheating method of construction of the present invention;
Fig. 6 is preheating step two schematic representation that have tapered pipeline in the directly buried pipeline electric preheating method of construction of the present invention;
Fig. 7 is the annexation schematic representation that is provided with compensator in the directly buried pipeline electric preheating method of construction of the present invention.
Embodiment
Understand for technical characteristics of the present invention, purpose and effect being had more clearly, now contrast description of drawings the specific embodiment of the present invention.
Fig. 1 is the trench cross-section schematic representation that is provided with pipeline in the directly buried pipeline electric preheating method of construction of the present invention, has schematically shown each sandy soil layer of backfill; Fig. 2 is the annexation schematic representation of directly buried pipeline electric preheating method of construction of the present invention; Fig. 3 is the distolateral portion's schematic representation of looking of pipeline in the directly buried pipeline electric preheating method of construction of the present invention, has schematically shown the position that is provided with of bolt; Fig. 4 is that the pipe end master looks schematic representation in the directly buried pipeline electric preheating method of construction of the present invention, schematically shown bolt and on pipe lengths the position has been set.
As shown in the figure, the directly buried pipeline electric preheating that the present invention proposes is executed the formula method and is comprised: construction sequence excavation groove 1 routinely, pipeline is put into described groove 1.Backfill sandy soil in being provided with the groove 1 that is preheated segment pipe 2, for not backfill sandy soil in the predetermined range at the two end part that are preheated segment pipe 2, promptly, the sandy soil of this backfill have a predetermined distance apart from the two end part that are preheated segment pipe 2, wherein, that part of pipeline of determining to carry out The pre-heat treatment in the described pipeline is called and is preheated segment pipe 2.The two end part that are preheated segment pipe 2 are hermetically enclosed, to prevent that managing interior hot gas scatters and disappears.For example, in a feasible embodiment, seal by covering plastic end cap, or carry out hermetically enclosed with the non-thermal conductor that other well known materials is made at the two end part that are preheated segment pipe.The described two end part that are preheated segment pipe 2 are connected with at least one elastic cable paper respectively, and described elastic cable paper connects power supply unit, form the loop of a sealing.Near the end that is preheated segment pipe 2 pipeline elongation detection device is being set.At an end that is preheated segment pipe temperature transducer is set, to adjust described current in loop amount at any time.Before being preheated segment pipe 2 energisings, to write down temperature transducer initial temperature that shows and the initial position of stretching amount detecting device at least.Described after testing be preheated the temperature and elongation that segment pipe 2 reaches regulation after, and whole groove 1 carried out backfill and compacting.After trench backfill is finished, cut off system power supply, remove the preheating device that is provided with it on, i.e. dismounting is arranged on the device that the elastic cable paper that is preheated on the segment pipe, temperature transducer, elongation detection device, connecting bolt etc. are used for pipeline is carried out The pre-heat treatment.
As shown in Figure 1, before the beginning preheating, in groove 1, fill out bottom earlier and bury sandy soil L1, these bottom sandy soil L1 is tamped, put into then and be preheated segment pipe 2, the height that is backfilled to the landfill sandy soil layer L2 in the described groove 1 will reach described about 3/4 of segment pipe 2 external diameters that are preheated highly to be located, and compacting; Continue backfill top layer sandy soil L3 at last to exceeding the described about 50mm of segment pipe 2 external diameters that is preheated, must not tamp.And the landfill sandy soil L2 of this backfill, top layer sandy soil L3 are about 12 meters apart from the about h of distance at the two end part that are preheated segment pipe 2.
Be preheated in the segment pipe 2 described, if having elbow, then before preheating, earthing not in the groove 1 of elbow.That is, not backfill of the part sandy soil in two meters of the both sides of elbow can move freely after elbow is heated guaranteeing.If preheating again behind the necessary earthing in elbow then need be provided with foam in the elbow back crook, then earthing.In the elbow displacement measurement device is set, the sharp total displacement amount of preheating section that calculates.
Be preheated in the segment pipe 2 described, if having threeway, then all branch's threeways must keep spacious ditch (that is, being provided with not backfill sandy soil in the groove 1 of threeway place) to guarantee that threeway can move freely in warm.Threeway can not be connected with branch pipeline before the preheating.After must waiting preheating to finish, after the retraction of preheating pipeline section was stable, threeway could be connected with lateral.In addition, all need carry out hermetically enclosedly, and guarantee do not have ponding in the segment pipe, in order to avoid short circuit occurs after the energising whole described being preheated for being preheated in the segment pipe 2 laterals such as threeway that exist.
Further, weld at least one bolt at the described two end part that are preheated segment pipe 2, described elastic cable paper is connected with described bolt.Shown in Fig. 3,4, in the present embodiment, weld a plurality of bolts 21 at the described two ends that are preheated segment pipe 2, about the 100mm of interval, each bolt 21 and an elastic cable paper are fixedly connected between each bolt 21.The distance H of the described pipe end of described bolt 21 distances is more than or equal to 30mm.For example, can weld 7 or 5 bolts that specification is M12x16-25, elastic cable paper 3 of each bolt connection apart from directly over by the pipeline external surface at the port 30mm place of pre-right segment pipe.
As shown in Figure 2, when described when being preheated segment pipe 2 and comprising water supply line 22 and water return pipeline 23, an end is connected in series by short-circuiting cable line 4 between described water supply, the water return pipeline 22,23, the other end is connected with power supply unit by elastic cable paper 3, makes to be preheated the loop that forms a sealing between segment pipe and the power supply unit.
Described pipeline elongation detection device (not shown) is arranged on usually apart from the about 2 meters position, end that is preheated segment pipe 2, this pipeline elongation detection device for example can be a gage, can be fixed in to be preheated on the outer surface that segment pipe 2 is easy to observe.On the described the longest straight length that is preheated segment pipe, two length check devices are installed at least, are calculated the conformity of elongation and theoretical elongation with checking.And before being preheated the segment pipe energising, mark zero elongation position on gage.
In addition, described temperature transducer 5 is arranged on usually apart from about 11 meters-12 meters position, end that is preheated segment pipe, to guarantee the accuracy of the preheating temperature of being surveyed.
In to the described heating process that is preheated segment pipe, the length change amount of the measured pipeline of the shown temperature value of described temperature transducer and elongation detection device is carried out three times at least to be measured, can calculate theoretical elongation by temperature, compare with actual elongation, guarantee that whole warm meets the requirements.
In addition, described being preheated in the segment pipe when pipe diameter changes needs by reducer fitting, is called reducing 6 again the pipeline of two sections different-diameters is connected.
Fig. 5 is preheating step one schematic representation that has tapered pipeline in the directly buried pipeline electric preheating method of construction of the present invention; Fig. 6 is preheating step two schematic representation that have tapered pipeline in the directly buried pipeline electric preheating method of construction of the present invention.
When having reducer pipe, because the pipeline wall thickness difference that reducing 6 two ends connect (wall thickness of large-diameter pipeline is greater than the wall thickness of small diameter pipeline usually), the resistance difference of unit length, therefore when carrying out electric preheating, large diameter pipeline can occur heats up slow, the situation of small-bore pipeline quick heating causes whole temperature rise and the elongation that is preheated segment pipe inconsistent at last.For avoiding the appearance of this problem, when dividing preheating section, carry out segmentation at the reducer pipe place usually, make the reducing place be positioned at the starting point or the end of preheating section.
If the condition of job site does not allow reducing is placed on starting point or end, then need the pipeline of different wall in the preheating section (different-diameter) is calculated warming velocity and preheating temperature that finally can reach and elongation respectively.Promptly, be preheated when having reducer pipe in the segment pipe when described, in each both sides, reducing place temperature transducer is set, in real time the temperature of reducing place both sides pipeline is measured, thereby prevent small-bore pipe the channel temp too fast and too high destruction thermal insulation layer that raises, and the preheating temperature that the pipeline of different-diameter is calculated warming velocity respectively and finally reaches.
The concrete steps that segment pipe carries out preheating that are preheated to band reducing 6 are, at first as shown in Figure 5, the water supply that the diameter that is connected reducing 6 one sides is bigger, an end of water return pipeline 22,23 are connected with power supply unit by elastic cable paper 3, be connected the small diameter pipeline 22 ' of reducing 6 opposite sides, 23 ' end is connected in series by short-circuiting cable line 4.Because the pipe diameter at reducing 6 two ends is different with wall thickness, small diameter pipeline 22 ', 23 ' temperature rise can supply water than major diameter, that water return pipeline 22,23 temperature rise is fast, therefore temperature transducer 5 is set respectively on the pipelines on two sides of reducing 6, monitor the temperature of reducing 6 two ends pipelines respectively, when small diameter pipeline 22 ', 23 ' temperature reach preheating requirement, stop heating to this section of tubing, and to be provided with small diameter pipeline 22 ', 23 ' pipe trench carries out backfill.Then as shown in Figure 6, to connect small diameter pipeline 22 ', 23 ' short-circuiting cable line 4 is removed, and there is the position of an interval S to be welded to connect bolt 21 at the welding bead place of the heavy caliber end of distance reducing 6 and water supply, water return pipeline 22,23, this short-circuiting cable line 4 is connected with described connecting bolt 21, makes the loop that forms a sealing between the bigger water supply of this diameter, water return pipeline 22,23 and the power supply unit.Preferred described interval S should be greater than 200mm.Again start, and adjust the output current of pre-heating device, wherein, the setting method of connecting bolt 21 and that the position is set is identical with above-mentioned bolt method of welding at the two end part that are preheated segment pipe 2 does not repeat them here.
Fig. 7 is the annexation schematic representation that is provided with compensator in the present invention's directly buried pipeline electric preheating of the present invention method of construction.As shown in the figure, described when being preheated the valve (not shown) that has compensator 7 in the segment pipe or be connected by flange, on the described pipeline that is connected in described valve or compensator both sides, bolt is set, and the bolt that is provided with on the described pipeline with jump leads 8 and described compensator 7 or valve both sides is connected, to reduce preheat current flow through this compensator or valve.Wherein, the bolt method in valve or the setting of compensator both sides is the same with the bolt method of welding at the described two end part that are preheated segment pipe 2.And,, can make the heat resisting temperature of the interior temperature rise of passing through that electric current caused of described valve or compensator less than valve or compensator inner seal liner by the setting of described jump leads 8.
For the valve that is provided with in being preheated segment pipe is when being connected on the pipeline by the method for welding, can valve not to be carried out special processing, valve is handled getting final product as straight tube.
The directly buried pipeline electric preheating method of construction that the present invention proposes is connected with power supply unit by being preheated segment pipe, constitute a closed-loop path, the section of being preheated pipeline section is applied the electric energy of low voltage, high electric current, utilize the principle of pipeline (steel pipe) self-resistance heating, the temperature of steel pipe is heated to the design preheating temperature.This method of construction is simple, and with known wind preheating, that water preheat is compared thermal losses is little, preheating is even, and required preheat time is short, has shortened construction period, greatly the manufacturing efficiency of Ti Gaoing.In addition, the present invention adopts low voltage, high electric current to carry out The pre-heat treatment, for example can select for use the electric current of 20-56V voltage, 3000-10000A to carry out The pre-heat treatment, thereby guarantee construction safety effectively.
Following table is directly buried pipeline electric preheating method of construction of the present invention and the comparison of adopting water preheat, wind preheating method of construction:
| Pre-thermal uniformity | Comparatively even | Temperature drop is very big, and is least even | Very even |
| Preheat time | Chronic, more than the week | Time is longer | Time is short, and general needs 10-20 hour |
| Elongation control | Because the weight of water causes frictional force big, be difficult for elongation, wayward | Non-uniform temperature, elongation is inhomogeneous, and is wayward | Elongation evenly can accurately be controlled |
| Influence to pipeline | Less | Less | Have no effect |
| Pre-heat effect | Stress in the steel pipe is difficult to abundant release, and pre-heat effect is bad | Preheating is inhomogeneous, and effect is relatively poor | Pre-heat effect is best |
| The preheating expense | Expense is very high | Expense is very high | Expense is low |
| Prospect | Be eliminated gradually | Be eliminated gradually | Main preheating method |
Energy consumption relatively
The above only is the schematic embodiment of the present invention, is not in order to limit scope of the present invention.Any those skilled in the art, equivalent variations and the modification done under the prerequisite that does not break away from design of the present invention and principle all should belong to the scope of protection of the invention.
Claims (10)
1. directly buried pipeline electric preheating method of construction comprises:
The excavation groove is put into described groove with pipeline;
Backfill sandy soil in being provided with the groove that is preheated segment pipe make the sandy soil of this backfill apart from the two end part that are preheated segment pipe one predetermined distance be arranged;
The two end part that are preheated segment pipe are hermetically enclosed, to prevent that managing interior hot gas scatters and disappears;
The described two end part that are preheated segment pipe are connected with at least one elastic cable paper respectively, and described elastic cable paper connects power supply unit, form the loop of a sealing;
Near the end that is preheated segment pipe pipeline elongation detection device is being set;
At an end that is preheated segment pipe temperature transducer is set, to adjust described current in loop amount at any time;
Before being preheated the segment pipe energising, to write down the initial temperature of temperature transducer demonstration and the initial position of elongation detection device at least;
Described after testing be preheated the temperature and elongation that segment pipe reaches regulation after, and whole groove carried out backfill and compacting;
After trench backfill is finished, cut off system power supply, remove and be preheated the preheating device that is provided with on the segment pipe.
2. directly buried pipeline electric preheating method of construction as claimed in claim 1 is characterized in that, welds at least one bolt at the described two end part that are preheated segment pipe, and described elastic cable paper is connected with described bolt; When being welded with a plurality of bolt at the described two ends that are preheated segment pipe, interval 100mm between each bolt, each bolt and an elastic cable paper are fixedly connected; And the distance of the described pipe end of described bolt distance is more than or equal to 30mm.
3. directly buried pipeline electric preheating method of construction as claimed in claim 1 is characterized in that, described being preheated when having bigger pipeline of diameter and small diameter pipeline in the segment pipe carried out segmentation at the reducing place, makes the reducing place be positioned at the starting point or the end of preheating section.
4. directly buried pipeline electric preheating method of construction as claimed in claim 1, it is characterized in that, described being preheated when having bigger pipeline of diameter and small diameter pipeline in the segment pipe, in each both sides, reducing place temperature transducer is set, in real time the temperature of reducing place both sides pipeline is measured, and the preheating temperature that the pipeline of different-diameter is calculated warming velocity respectively and finally reaches.
5. as claim 3 or 4 described directly buried pipeline electric preheating method of construction, it is characterized in that, an end that is connected the bigger pipeline of reducing one side diameter is connected with power supply unit by elastic cable paper, the end that is connected the small diameter pipeline of reducing opposite side is connected in series by the short-circuiting cable line; When the temperature of small diameter pipeline reaches preheating requirement, stop heating to this section of tubing; The short-circuiting cable line that connects small diameter pipeline is removed, and this short-circuiting cable line is connected to the other end of the bigger pipeline of the described diameter that is connected with described reducing, make the loop that forms a sealing between bigger pipeline of this diameter and the power supply unit, continuation is carried out preheating to the bigger pipeline of this diameter, and the groove that small diameter pipeline is set is carried out backfill.
6. directly buried pipeline electric preheating method of construction as claimed in claim 5 is characterized in that, the distance of the described reducing of joint distance of the pipeline the other end that described short-circuiting cable line and described diameter are bigger is greater than 200mm.
7. directly buried pipeline electric preheating method of construction as claimed in claim 1, it is characterized in that, described when being preheated the valve that has compensator in the segment pipe or be connected by flange, on the described pipeline that is connected in described valve or compensator both sides, bolt is set, and the bolt that is provided with on the described pipeline with jump leads and described valve or compensator both sides is connected, and makes the temperature rise that electric current caused passed through in described valve, the compensator heat resisting temperature less than valve or compensator inner seal liner.
8. directly buried pipeline electric preheating method of construction as claimed in claim 1 or 2 is characterized in that, the described segment pipe that is preheated comprises water supply line and water return pipeline, is connected in series by the short-circuiting cable line between described water supply, the water return pipeline.
9. directly buried pipeline electric preheating method of construction as claimed in claim 1 is characterized in that, on the described the longest straight length that is preheated segment pipe two length check devices is installed at least, calculates the conformity of elongation and theoretical elongation with checking; And the described two end part that are preheated segment pipe are sealed by covering plastic end cap.
10. directly buried pipeline electric preheating method of construction as claimed in claim 1 is characterized in that, before the beginning preheating, is backfilled to 3/4 place highly that sandy soil height in the described groove will reach described outer diameter tube, and tamps; Continue then to be backfilled to and exceed described outer diameter tube 50mm, must not tamp; And the sandy soil of this backfill are about 12 meters apart from the distance that is preheated the two end part of segment pipe, described pipeline elongation detection device is arranged on apart from the about 2 meters position, end that is preheated segment pipe, and described temperature transducer is arranged on apart from about 11 meters-12 meters position, end that is preheated segment pipe; In to the described heating process that is preheated segment pipe, the length change amount of the measured pipeline of the shown temperature value of described temperature transducer and elongation detection device is carried out three times at least measure.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200910243296 CN101975324B (en) | 2009-12-30 | 2009-12-30 | Method for electric preheating construction of directly-buried pipeline |
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| CN 200910243296 CN101975324B (en) | 2009-12-30 | 2009-12-30 | Method for electric preheating construction of directly-buried pipeline |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103511743A (en) * | 2013-07-15 | 2014-01-15 | 北京豪特耐管道设备有限公司 | Electric pre-heating construction method for exceedingly-long pipeline |
| CN111442133A (en) * | 2020-01-19 | 2020-07-24 | 济南热力工程有限公司 | Large-pipe-diameter electric preheating compensation control method |
| CN111779886A (en) * | 2020-01-19 | 2020-10-16 | 济南热力工程有限公司 | Electric preheating compensation method for large-diameter long-heat-transmission pipeline |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1594959A (en) * | 2003-09-12 | 2005-03-16 | 天津市暖风机总厂 | Heat supply direct-buried pipe hot air preheating method and hot air supply apparatus used thereby |
| CN2836064Y (en) * | 2005-09-28 | 2006-11-08 | 李康宁 | Compensation-less electric preheater for thermal network |
| DE202006006307U1 (en) * | 2006-04-18 | 2007-08-30 | Michael Hesky Gmbh | Arrangement for the preparation of pipelines |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103511743A (en) * | 2013-07-15 | 2014-01-15 | 北京豪特耐管道设备有限公司 | Electric pre-heating construction method for exceedingly-long pipeline |
| CN103511743B (en) * | 2013-07-15 | 2015-09-23 | 北京豪特耐管道设备有限公司 | A kind of super-long pipeline electric preheating method of construction |
| CN111442133A (en) * | 2020-01-19 | 2020-07-24 | 济南热力工程有限公司 | Large-pipe-diameter electric preheating compensation control method |
| CN111779886A (en) * | 2020-01-19 | 2020-10-16 | 济南热力工程有限公司 | Electric preheating compensation method for large-diameter long-heat-transmission pipeline |
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| CN101975324B (en) | 2012-05-09 |
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