CN112588038B - Prefabricated cold end method - Google Patents
Prefabricated cold end method Download PDFInfo
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- CN112588038B CN112588038B CN202011342600.8A CN202011342600A CN112588038B CN 112588038 B CN112588038 B CN 112588038B CN 202011342600 A CN202011342600 A CN 202011342600A CN 112588038 B CN112588038 B CN 112588038B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D46/00—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
- B01D46/42—Auxiliary equipment or operation thereof
- B01D46/4263—Means for active heating or cooling
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B3/00—Ohmic-resistance heating
- H05B3/40—Heating elements having the shape of rods or tubes
- H05B3/54—Heating elements having the shape of rods or tubes flexible
- H05B3/56—Heating cables
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Abstract
A method for prefabricating a cold end belongs to the technical field of heating, and particularly relates to a method for prefabricating a cold end. The invention provides a prefabricated cold end method with convenient connection. The method for prefabricating the cold end comprises the following steps: the heating core wire, the insulating layer and the outer sleeve are assembled, the cold end wire core is welded at the two ends of the heating core wire and the insulating layer and the outer sleeve to serve as a non-heating section, and the heating section and the cold end surface of the prefabricated cold end heating cable are formed by a whole seamless pipe.
Description
Technical Field
The invention belongs to the technical field of heating, and particularly relates to a method for prefabricating a cold end.
Background
The process gas temperature of the high-temperature flue gas filter during operation is up to 520-550 ℃, and all the high-temperature filters are in a working state under a normal state. The filter may become clogged in a relatively short period of time and therefore requires periodic cleaning after a certain amount of filter dust has accumulated on the filter rod. When one filter is used for ash removal maintenance, the other filters are continuously kept in operation, and impurities in the process gas can be completely removed. After the high temperature filter to be cleaned is cut, the filter is heated. Then pulse dedusting is carried out after ensuring that the nitrogen pressure is high enough (about 5-6 bar) and the temperature of the high-temperature flue gas filter is high enough (500 ℃). After two-round pulse dust removal, the filter is heated to above 400 ℃ again, and medium gas is introduced for use. If the filter is overhauled, the temperature needs to be raised before the process gas is introduced after the overhaul is finished, and the medium gas is introduced after the temperature of the filter is higher than 400 ℃. Therefore, a heating system is needed for heating the high-temperature flue gas filter before starting, maintaining the temperature in the running process and removing dust. The heating system needs to be connected with a cold end lead, so that a cold end lead connection mode which is convenient to connect is needed.
Disclosure of Invention
The invention aims at the problems and provides a method for prefabricating a cold end, which is convenient to connect.
In order to achieve the purpose, the invention adopts the following technical scheme that the method for prefabricating the cold end comprises the following steps: the heating core wire, the insulating layer and the outer sleeve are assembled, the cold end wire core is welded at the two ends of the heating core wire and the insulating layer and the outer sleeve to serve as a non-heating section, and the heating section and the cold end surface of the prefabricated cold end heating cable are formed by a whole seamless pipe.
As a preferable scheme, the cold end lead penetrates through the terminal joint to be welded with the lead, the welding position is arranged at the rear end of the terminal joint, and the lead is connected with the temperature control box through the junction box.
As another preferable scheme, the insulating layer of the present invention is a magnesium oxide insulating layer.
As another preferable scheme, the cold-end wire core adopts an N6 wire core.
As another preferable mode, the seamless pipe of the present invention is a steel pipe.
As another preferred scheme, the terminal joint of the present invention comprises a front end connector and a rear end connector, wherein the front end connector has a structure with a central through hole Contraband, the rear end connector comprises a front end insertion portion and a rear end connection portion, the outer wall of the front end insertion portion and the inner wall of the front end connector are correspondingly provided with threads, the central portions of the front end insertion portion and the rear end connection portion are provided with through holes for communication, and a cold end lead passes through the through holes; the outer wall of the rear part of the rear end connecting part is provided with an external thread.
As another preferable scheme, the rear end of the through hole of the front end connector is in a horn shape which is increased from front to back, and the front end of the through hole of the front end insertion part is in a horn shape which is decreased from front to back;
the rear end aperture of the through hole of the front end insertion part is larger than the front aperture, and the joint of the rear end aperture and the front aperture is in a horn shape which is increased from front to back;
the aperture of the through hole of the rear end connecting part is larger than that of the through hole of the front end inserting part, and the connecting part of the rear end of the through hole of the front end inserting part and the through hole of the rear end connecting part is in a horn shape which is increased from front to back.
As another preferable scheme, the outer wall of the rear end of the front end connector extends outwards to form a wrench convex block, and the outer wall of the rear end connector at the rear end of the front end connector extends outwards to form a wrench convex block.
As another preferred scheme, a sealant piece with an inner contour and an outer contour corresponding to the through hole of the rear-end connecting part is inserted into the through hole of the rear-end connecting part, and epoxy resin sealant is arranged between the side wall of a large hole of the sealant piece and the cold-end lead.
As another preferable scheme, locking beads are arranged around the cold end lead at the trumpet-shaped part at the rear end of the through hole of the front end connector and the trumpet-shaped part at the front end of the through hole of the front end insertion part.
As another preferable mode, the heating cable according to the present invention is installed at a pitch of not more than 50 mm.
As another preferable mode, the heating cable of the present invention is disposed on the surface of the device by a pre-punched tape.
The pre-punched strip comprises a bottom strip, hook-shaped parts bent towards the length direction of the pre-punched strip are arranged on the upper end face of the strip, the number of the hook-shaped parts is multiple, the hook-shaped parts are uniformly distributed along the length direction of the pre-punched strip, and the bending directions of the hook-shaped parts are consistent.
In addition, the pre-punched belt of the invention is a stainless steel pre-punched belt.
The invention has the beneficial effects.
The invention adopts a prefabricated cold end mode, and is convenient to connect. The heating section and the cold end surface of the prefabricated cold end heating cable are formed by a whole seamless steel pipe, no welding point exists, and the problem of welding seam cracking in long-term use can be avoided.
Drawings
The invention is further described with reference to the following figures and detailed description. The scope of the invention is not limited to the following expressions.
FIG. 1 is a schematic view of the thermocouple arrangement according to the present invention.
Fig. 2 and 3 are schematic views of the structure of the pre-punched hole of the present invention.
Figure 4 is a view of the use of the pre-punched tape of the present invention.
FIG. 5 is a schematic view of a prefabricated cold end construction of the present invention.
Fig. 6 and 7 are schematic structural views of the temperature control box of the invention.
Fig. 8, 9 and 10 are circuit diagrams of the temperature control box of the invention.
Fig. 11 is a schematic view of a terminal fitting structure of the present invention.
In fig. 1 to 5, 1 is an explosion-proof junction box, 2 is a thermocouple, 3 is a sleeve, 4 is a T-shaped connector, 5 is a protection tube, 6 is a hot end fixing block, 7 is a device body surface, 8 is a hook-shaped part, 9 is a strip-shaped strip, 10 is a heating cable, 11 is a heating section, 12 is a cold end lead, 13 is a prefabricated cold end and hot end wire core welding point, 14 is epoxy resin sealant, 15 is a lead section, 16 is a sealant, 17 is a rear end connector, 18 is a front end connector, and 19 is a locking bead.
Detailed Description
As shown in the figure, the method for prefabricating the cold end is applied to a heating system, the heating system comprises a heating part, a temperature control box and a temperature measuring element, a detection signal input port of the temperature control box is connected with a detection signal output port of the temperature measuring element, and a control signal output port of the temperature control box is connected with a control signal input port of the heating part. The heating system is convenient for controlling the heating temperature and has good heating effect through the matching of all parts.
The heating part adopts a heating cable.
The heating part adopts an armored mineral insulated heating cable.
The purity of magnesium oxide in the magnesium oxide insulating layer of the armored mineral insulating heating cable is more than or equal to 97 percent.
The magnesium oxide insulating layer contains SiO2And (3) components.
The SiO2The mass percentage of the components is 1-2%.
The carbon content of the magnesia porcelain column as the magnesia raw material is not more than 0.03%; can improve the insulating property of the heating cable, reduce the surface temperature load of the heating cable and prolong the service life of the heating cable
The granularity of the magnesia ceramic post is more than 200 meshes, the sintering temperature is 1200-1300 ℃, and the sintering time is 2 hours.
An ultrasonic cleaning procedure is arranged before the heating core wire of the armored mineral insulation heating cable is assembled, and grease on the surface of the heating core wire is removed through an ultrasonic cleaning machine. The grease is prevented from being carbonized in the subsequent processing process and mixed into the insulating layer, so that the high-temperature insulating property of the heating cable is prevented from being influenced.
The heating core wire heating section is made of a NiCr20 or NiCr10 core wire, the cold end is made of an N6 core wire, the monofilament diameter of the core wire is phi 0.5-phi 9, the 20 ℃ resistivity of the NiCr20 or NiCr10 core wire is 69 mu omega cm-117 mu omega cm, and the 20 ℃ resistivity of the N6 core wire is 6.84 mu omega cm.
And (3) heating core wire welding: the method comprises the following steps that N6 core wires are welded at two ends of a heating section (NiCr20 or NiCr10 core wires), argon arc welding is adopted in a welding mode, a heating cable core wire is formed by sequentially connecting a cold section, a heating section and a cold section in series, the resistivity of the cold section core wire is greatly different from that of the heating section core wire, when the two ends of a heating cable are electrified, the heating section and the cold section core wire are connected into the same series circuit, the part with large resistivity is high in heating power, the part with small resistivity is low in heating power, and the heating power of the heating section is at least 10 times different from that of the cold section.
The forging and rolling and polishing are carried out aiming at welding spots of the heating section and the cold section, the welding spots are processed through forging and rolling and polishing, the outer diameter of each welding spot is consistent with the outer diameter of the core wire, and the phenomenon that the insulation layer at the position is thin due to the fact that the welding spots are too large and the insulation resistance of the heating cable is influenced is prevented. The heating core wire is coiled into a circle by the take-up reel after being stretched, and the heating core wire is straightened into a straight line by the straightening machine before being assembled, so that the assembly is convenient. Before assembling, the core wire is subjected to vacuum annealing treatment at the annealing temperature of 800 ℃ and is stretched into the armored cable.
After a heating core wire, a magnesium oxide insulating layer and an outer sleeve of the armored mineral insulating heating cable are assembled and before drawing is started, a drying procedure is set, bound water in magnesium oxide molecules is separated, and protective gas is introduced during drying to prevent the outer sleeve and the heating core wire from being oxidized.
The outer sleeve is firstly milled (the assembled outer sleeve is milled to be thin so as to pass through the stretching die), and the length of the milled end is 100-200 mm. After the wire core is threaded on the magnesium columns, no gap exists between the magnesium columns, and the wire core is placed in the outer sleeve at a constant speed. The tail part of the outer sleeve is clamped flat (the magnesium column is prevented from sliding out of the tail part), stretched and clasped, and then is sent to annealing treatment.
The stretching process comprises the following steps: 1.Φ 25 → Φ 21 → anneal → Φ 19 → anneal → Φ 17 → anneal → Φ 16 → anneal → Φ 14 → anneal → Φ 13 → anneal → Φ 12 → anneal → Φ 11 → anneal → Φ 10 → anneal → Φ 9.0 → anneal → Φ 8.0 → anneal → Φ 7.2 → anneal → Φ 6.5 → anneal → Φ 6.0 → anneal → Φ 5.5 → anneal → Φ 5.0 → anneal → Φ 4.5 → anneal → Φ 4.0 → anneal.
The annealing adopts 2 modes, wherein the first mode is vacuum annealing, the annealing temperature is 800-880 ℃, the other mode is over-annealing, the annealing temperature is 900-1100 ℃, and nitrogen or hydrogen is filled for protection during annealing to prevent the surface of the heating cable from being oxidized.
The heating cable for vacuum annealing is coiled into a disc, and labels are marked in batches for annealing.
When the material is taken, the material is hung by a crane.
And (3) prediction: and (4) predicting before finished products are produced, and measuring the total resistance of the heating wire, the lead meter resistance of the cold end, the outer diameter of the heating wire, the length of a heating area and the length of a non-heating area.
And (3) checking the semi-finished product coil material by coil and breaking the head (including surface, existence of transverse and longitudinal cracks, outer diameter and electrical insulation), then putting the semi-finished product coil material into a drying box, drying the semi-finished product coil material within the range of 150 plus materials and 200 ℃ until the insulation is qualified, sealing the semi-finished product coil material, and searching and marking the junction point of the heating area and the non-heating area after the semi-finished product coil material is completely gelled. And measuring the total resistance of the heating wire, the lead resistance of the cold end, the outer diameter of the heating wire, the length of the heating area and the length of the non-heating area after searching is finished, and calculating the size of a finished product according to the data and the requirements of production cards.
The boundary point searching method adopts physical magnetism searching, N6 attracts a magnet, and the heating section material does not have obvious reaction when contacting the magnet.
Polishing is carried out before bright annealing and during finishing.
The sandpaper type and the rotational speed of the polisher.
Type of sand paper: 60#100#180#240#320#400#600#1000 #.
The rotating speed of the polishing machine is as follows: 100 to 350 r/min.
Liquid crystal display of the frequency converter of the wire rewinding machine: 1 to 11.
And (3) finished product detection: and (3) detecting finished product coil materials by coil and breaking ends (including surface, existence of transverse and longitudinal cracks, outer diameter, total resistance, heating area length, cold end length, electric insulation and the like), remanufacturing or marking unqualified products, tying a label after the finished products are qualified, drying and sealing the label, recording, and warehousing (water immersion is needed to detect leakage points before a finished product die is stretched).
Blanking and manufacturing:
1. before blanking, finished coil materials are taken according to production cards, and checking volume ventilation, insulation, total resistance of a heating wire, length of a heating area and length of a cold end are carried out.
2. Testing before blanking, blanking after being qualified, and if not, testing after retreating. .
3. According to the standard, the diameter of a disc with the diameter more than 5.0mm is 450mm, the diameter of a disc with the diameter more than 3.0mm is 300mm, the diameter of a disc with the diameter of 1.0-2.0 mm is 170mm, and the diameter of a disc with the diameter less than 1.0mm is 100 mm. The length error of each cable is 50-500 mm.
4. After blanking, the two parts are bound by iron wires at a fixed length of more than 5 meters, the two ends are left to be 200-300 mm long, then the ends are broken, and the inner wires are broken at the two ends by 20 mm.
5. Putting the raw materials into a drying oven according to specification, variety and quantity, and drying at 150-200 ℃ until the insulation resistance is qualified to obtain the end socket (sealing epoxy resin sealant).
After a heating core wire, a magnesium oxide insulating layer and an outer sleeve of the armored mineral insulated heating cable are assembled and before drawing is started, a drying procedure of 600 ℃ for 2 hours is set, bound water in magnesium oxide molecules is separated, and H2 or N2 is introduced to serve as protective gas during drying, so that oxidation of the outer sleeve and the heating core wire is prevented. The bound water can be separated from the magnesium oxide only when the temperature of the bound water is more than 500 ℃, and if the bound water is not sufficiently separated from the magnesium oxide in the manufacturing process, the insulation resistance of the heating cable above 500 ℃ is seriously influenced when the service temperature of the heating cable exceeds 500 ℃.
The thickness of the insulating layer of the armored mineral insulating heating cable is 1.2 mm. Repeated tests prove that the thickness can effectively improve the high-temperature insulation resistance of the heating cable, and the installation difficulty cannot be too large due to excessive increase of the outer diameter.
The armored mineral insulated heating cable has the following measurement results of high-temperature insulation resistance power-on heating (the length of the heating section of the test sample is 24 meters):
| temperature of | High temperature edge resistance M omega |
| 300 | 350 |
| 400 | 100 |
| 500 | 20 |
| 600 | 1.5 |
| 650 | 0.5 |
| 800 | 0.1 |
The above table shows that the armored mineral insulated heating cable has high-temperature insulation resistance, and meets the requirement of long-term high-temperature stable operation of the electric heating (heat tracing) system of the high-temperature flue gas filter.
The wall thickness of an outer sleeve of the armored mineral insulated heating cable is 12% of the outer diameter of the armored mineral insulated heating cable; effectively prolong the service life of the heating cable in a long-term high-temperature environment.
The prefabricated cold end mode is as follows: the heating core wire, the magnesium oxide insulating layer and the outer sleeve are assembled, the N6 wire cores (cold end lead wires are welded at the two ends of the heating core wire before assembly, the heating power is low, people are prevented from being injured, and terminal joints are prevented from being damaged by scalding) are used as non-heating sections, and the heating section and the cold end surface of the prefabricated cold end heating cable are formed by a whole seamless steel pipe.
The cold end lead penetrates through the terminal joint to be welded with the lead, the welding position is arranged at the rear end of the terminal joint, and the lead is connected with the temperature control box through the junction box. The terminal connector is arranged to be conveniently connected with the junction box.
The terminal joint comprises a front end connecting body and a rear end connecting body, the front end connecting body is of a structure with a through hole Contraband in the middle, the rear end connecting body comprises a front end inserting part and a rear end connecting part, the outer wall of the front end inserting part and the inner wall of the front end connecting body are correspondingly provided with threads, the middle parts of the front end inserting part and the rear end connecting part are provided with communicated through holes, and a cold end lead passes through the through holes; the outer wall of the rear part of the rear end connecting part is provided with an external thread. The external thread of the outer wall of the rear part of the rear end connecting part is matched with the internal thread hole of the junction box.
The rear end of the through hole of the front end connector is in a horn shape which is increased from front to back, and the front end of the through hole of the front end insertion part is in a horn shape which is decreased from front to back;
the rear end aperture of the through hole of the front end insertion part is larger than the front aperture, and the joint of the rear end aperture and the front aperture is in a horn shape which is increased from front to back;
the aperture of the through hole of the rear end connecting part is larger than that of the through hole of the front end inserting part, and the connecting part of the rear end of the through hole of the front end inserting part and the through hole of the rear end connecting part is in a horn shape which is increased from front to back.
The outer wall of the rear end of the front end connector extends outwards to form a wrench convex block, and the outer wall of the rear end connector of the rear end of the front end connector extends outwards to form a wrench convex block.
A sealant piece with the inner and outer contours corresponding to the through hole of the rear-end connecting part is inserted into the through hole of the rear-end connecting part, and epoxy resin sealant is arranged between the side wall of the large hole of the sealant piece and the cold-end lead; the sealing and moisture-proof performance is improved.
Locking balls are arranged around the cold end lead at the trumpet-shaped part at the rear end of the through hole of the front end connecting body and the trumpet-shaped part at the front end of the through hole of the front end inserting part; the sealing performance is improved.
The installation distance of the heating cables is not more than 50 mm. Effectively shorten the temperature difference between the surface of the heating wire and the temperature measuring point, further reduce the surface temperature of the heating cable and prolong the service life of the heating cable.
The heating cable is arranged on the surface of the equipment through a pre-punched belt. The pre-punched tape may be welded to the surface of the apparatus.
The pre-punching strip comprises a bottom long strip, hook-shaped parts bent towards the length direction of the pre-punching strip are arranged on the upper end face of the long strip, the hook-shaped parts are multiple and uniformly distributed along the length direction of the pre-punching strip, and the bending directions of the hook-shaped parts are consistent. The mounting mode guarantees that the armored mineral insulated heating cable is attached to the surface of the equipment to the maximum extent, suspended dry burning cannot be caused, and the service life of the heating wire is prolonged.
The distance between the lower end of the transverse edge of the hook-shaped component and the upper end of the long strip is 6mm, and the length of the transverse edge is 10 mm.
After the heating cable passes below the hook-shaped component, the hook-shaped component is pressed downwards to fix the heating cable.
The pre-punched belt is made of stainless steel.
The upper end of the temperature control box is provided with a rain cover.
The temperature control box is provided with a relay KM0, one end of a controlled normally-open switch of KM0 is connected with a power supply through a switch QF0, the other end of the controlled normally-open switch of KM0 is respectively connected with one end of a switch QF01, one end of a switch QF-B and one end of a switch QF-K, and the other end of a switch QF01 sequentially passes through an air switch and a controlled normally-open switch of the relay KM01 and is connected with a heat receiving part;
the other end of the switch QF-B is connected with a power supply end of a heat tracing loop through an air switch (the control box is heated through heat tracing, and the air switch is suitable for cold environments);
the other end of the switch QF-K is connected with a power supply end of the control circuit through an air switch.
The controlled normally open switch of relay KM01 in fig. 8 is controlled by the control terminal of relay KM in fig. 9.
As shown in FIG. 8, the temperature control box of the present invention can control 10 heating circuits.
As shown in fig. 9, TK denotes TK0 to TK10, and KM0 to KM10, corresponding to 10 heating circuits. The 3, 4-pin switch of SA0 and SA is interlocked with the 1, 2-pin switch, i.e. if the 3, 4-pin switch is open, the 1, 2-pin switch is closed. The signal input port of the temperature control meter is connected with the signal output port of the temperature measuring element.
The control loop comprises a change-over switch SA0, wherein a No. 3 contact of SA0 is respectively connected with a 001 end, a No. 1 contact of SA0, one end of a normally open switch of a controlled end of a relay KAO, one end of a switch QF-SD, one end of a control end of a relay TK, a No. 3 contact of a switch SA and a No. 1 contact of a switch SA;
a contact No. 4 of the SA0 is respectively connected with one end of a control end of a relay KA0 and a contact No. 2 of the SA0 through a relay K controlled switch, and the other end of the control end of the relay KA0 is respectively connected with an end 000, one end of a control end of a relay KM0, one end of an indicator lamp HL x 5, the other end of a control end of the relay TK and one end of a control end of the relay KM;
the control end of the relay K receives a remote control signal, the other end of the control end of the relay KM0 is connected with the other end of the normally open switch at the controlled end of the relay KAO, the other end of the indicator light HL 5 is connected with the other end of the switch QF-SD, the other end of the control end of the relay KM is respectively connected with one end of the normally open switch controlled by the relay TK and the No. 2 contact of the switch SA, and the other end of the normally open switch controlled by the relay TK is connected with the No. 4 contact of the switch SA.
The temperature measuring element adopts a thermocouple.
The thermocouple is arranged in the sleeve, the explosion-proof junction box is arranged at the upper end of the sleeve, the lower end of the sleeve is in threaded connection with the upper end of the protection tube, the lower end of the protection tube is connected with the upper end of the protection tube through the hot end fixing block (the hot end fixing block is arranged to prevent the thermocouple measuring end from being separated from the surface of equipment due to equipment vibration and inaccurate temperature measurement), and the bottom of the hot end fixing block is connected with the surface of the equipment. Has the advantage of convenient disassembly after failure. When the temperature measuring element is replaced, the machine does not need to be stopped and the temperature is not needed to be removed, and the temperature measuring element can be replaced at any time when the temperature measuring element breaks down.
The sleeve pipe lower extreme is provided with T shape connector, and T shape connector middle part is provided with the T shape hole, and the big hole in T shape hole is inserted to the sleeve pipe lower extreme, and sleeve pipe lower extreme outer wall meets with the big hole lateral wall in T shape hole, and the sleeve pipe internal diameter is greater than the aperture in T shape hole, and the welding of department of meeting of sleeve pipe lower part and T shape connector up end, the little head outer wall of T shape connector has the external screw thread, and protection tube upper end inner wall has the internal thread.
The middle part of the hot end fixing block is provided with a vertical through hole, the upper end of the vertical through hole is in a horn shape with a large upper part and a small lower part (the insertion is convenient when a thermocouple is replaced), and the aperture of the vertical through hole below the horn-shaped hole is the same as that of the lower end of the horn-shaped hole;
the inner wall of the lower end of the protection tube is sunken outwards, the side wall of the sunken part is connected with the outer wall of the hot end fixing block, and the upper end surface of the sunken part is connected with the upper end surface of the hot end fixing block; the lower end of the protection pipe is higher than the bottom of the hot end fixing block, the outer wall of the bottom of the hot end fixing block is welded with the surface of the tank body, and the joint of the lower end face of the protection pipe and the outer wall of the hot end fixing block is welded.
The temperature difference between the surface temperature of the heating cable and the temperature of the temperature measuring point is relatively low (the temperature measuring point is arranged between two parallel heating cables, the installation distance of the heating cables is 50mm, and the temperature measuring point and the heating cables are both tightly attached to the surface of equipment), the temperature control is more accurate, the surface temperature of the heating cable can be integrally reduced, and the service life is prolonged.
It should be understood that the detailed description of the present invention is only for illustrating the present invention and is not limited by the technical solutions described in the embodiments of the present invention, and those skilled in the art should understand that the present invention can be modified or substituted equally to achieve the same technical effects; as long as the use requirements are met, the method is within the protection scope of the invention.
Claims (7)
1. The method for prefabricating the cold end is characterized in that the cold end wire core is welded at two ends before the heating core wire, the insulating layer and the outer sleeve are assembled to serve as a non-heating section, and the heating section and the cold end surface of the prefabricated cold end heating cable are formed by a whole seamless pipe;
the insulating layer is a magnesium oxide insulating layer;
the terminal joint comprises a front end connecting body and a rear end connecting body, the front end connecting body is of a structure with a through hole Contraband in the middle, the rear end connecting body comprises a front end inserting part and a rear end connecting part, the outer wall of the front end inserting part and the inner wall of the front end connecting body are correspondingly provided with threads, the middle parts of the front end inserting part and the rear end connecting part are provided with communicated through holes, and a cold end lead passes through the through holes; the outer wall of the rear part of the rear end connecting part is provided with an external thread;
the rear end of the through hole of the front end connector is in a horn shape which is increased from front to back, and the front end of the through hole of the front end insertion part is in a horn shape which is decreased from front to back;
the rear end aperture of the through hole of the front end insertion part is larger than the front aperture, and the joint of the rear end aperture and the front aperture is in a horn shape which is increased from front to back;
the aperture of the through hole of the rear end connecting part is larger than that of the through hole of the front end inserting part, and the connecting part of the rear end of the through hole of the front end inserting part and the through hole of the rear end connecting part is in a horn shape which is enlarged from front to back;
and (3) heating core wire welding: welding core wires made of N6 materials at two ends of the heating section, wherein the welding mode adopts argon arc welding, and the core wires of the heating cable are formed by sequentially connecting a cold section, the heating section and the cold section in series;
forging, rolling and polishing are carried out aiming at welding points of the heating section and the cold section, and the welding points are subjected to forging, rolling and polishing treatment, so that the outer diameter of the welding points is consistent with the outer diameter of the core wire, and the phenomenon that the insulation layer at the position is thin due to overlarge welding points and the insulation resistance of the heating cable is influenced is prevented; the heating core wire is coiled into a circle by a take-up reel after being stretched, and the heating core wire is straightened into a straight line by a straightening machine before being assembled, so that the assembly is convenient; before assembling, the core wire is subjected to vacuum annealing treatment and is stretched into an armored cable;
the heating cable is arranged on the surface of the equipment through a pre-punched belt; the pre-punched strip comprises a bottom long strip, hook-shaped parts bent towards the length direction of the pre-punched strip are arranged on the upper end face of the long strip, the hook-shaped parts are uniformly distributed along the length direction of the pre-punched strip, and the bending directions of the hook-shaped parts are consistent;
the method for prefabricating the cold end is applied to a heating system, the heating system comprises a heating part, a temperature control box and a temperature measuring element, a detection signal input port of the temperature control box is connected with a detection signal output port of the temperature measuring element, and a control signal output port of the temperature control box is connected with a control signal input port of the heating part; the temperature measuring element adopts a thermocouple; the thermocouple is arranged in the sleeve, the explosion-proof junction box is arranged at the upper end of the sleeve, the lower end of the sleeve is in threaded connection with the upper end of the protection tube, the lower end of the protection tube is connected with the hot end fixing block, and the bottom of the hot end fixing block is connected with the surface of equipment.
2. The method of prefabricating a cold end according to claim 1 wherein the cold end lead is welded to the wire through a terminal fitting, the weld being located at the rear end of the terminal fitting, the wire being connected to the temperature controlled box by a junction box.
3. The prefabricated cold end method of claim 1, wherein said cold end wire core is N6 wire core.
4. The pre-fabrication cold end method of claim 1, wherein the seamless tube is a steel tube.
5. The prefabrication cold end method of claim 1, wherein the front end connector rear end outer wall extends outwardly to form a wrench tab, and the rear end connector rear end outer wall extends outwardly to form a wrench tab.
6. The prefabrication cold end method according to claim 1, wherein a sealant having an inner and outer contour corresponding to the through hole of the rear end connection portion is inserted into the through hole of the rear end connection portion, and an epoxy resin sealant is provided between a side wall of a large hole of the sealant and the cold end lead.
7. The prefabrication cold end method according to claim 1, characterized in that locking beads are arranged around the cold end lead at the trumpet-shaped part at the rear end of the through hole of the front end connecting body and the trumpet-shaped part at the front end of the through hole of the front end inserting part.
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| CN202011342600.8A CN112588038B (en) | 2020-11-25 | 2020-11-25 | Prefabricated cold end method |
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| CN202011342600.8A CN112588038B (en) | 2020-11-25 | 2020-11-25 | Prefabricated cold end method |
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| US4611394A (en) * | 1982-12-17 | 1986-09-16 | Gellert Jobst U | Method of manufacture of an injection molding integral heated probe |
| WO1998031195A1 (en) * | 1997-01-07 | 1998-07-16 | Nota Bene Ltd. | A heating cable and a method of making it |
| CN101772227A (en) * | 2010-01-27 | 2010-07-07 | 无锡赛丰仪表有限公司 | Armored heating cable |
| CN101909373A (en) * | 2010-04-29 | 2010-12-08 | 莱芜市富强特种线缆有限公司 | Heating cable with invisible joint and manufacturing method thereof |
| CN206380112U (en) * | 2016-12-30 | 2017-08-04 | 久盛电气股份有限公司 | A kind of high-temperature ignition cable |
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2020
- 2020-11-25 CN CN202011342600.8A patent/CN112588038B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4611394A (en) * | 1982-12-17 | 1986-09-16 | Gellert Jobst U | Method of manufacture of an injection molding integral heated probe |
| WO1998031195A1 (en) * | 1997-01-07 | 1998-07-16 | Nota Bene Ltd. | A heating cable and a method of making it |
| CN101772227A (en) * | 2010-01-27 | 2010-07-07 | 无锡赛丰仪表有限公司 | Armored heating cable |
| CN101909373A (en) * | 2010-04-29 | 2010-12-08 | 莱芜市富强特种线缆有限公司 | Heating cable with invisible joint and manufacturing method thereof |
| CN206380112U (en) * | 2016-12-30 | 2017-08-04 | 久盛电气股份有限公司 | A kind of high-temperature ignition cable |
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| CN112588038A (en) | 2021-04-02 |
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