RU2411435C1 - Method for increasing heat transfer of pipe surface of convection chamber with finning - Google Patents

Abstract

FIELD: power industry.

SUBSTANCE: on the pipe there arranged is spiral construction (spiral) from rolled metal of various sections (round, oval, triangular, square, etc.) with certain pitch, the inner surface of which is drilled, ground, passivated to provide tight adjoining with outer pipe surface. Inner surface of construction is lubricated with special compound to improve the sliding at tightening (installation) and to form servovit film at certain temperatures, which welds it to the pipe surface. Spiral is put on the pipe and front end is welded and spread with certain pitch according to the template; into the hole on the other spiral end there installed is safety hook with wire rope the end of which is fixed on the lever and tightened with force of 50-100 kgf and attached with cotter pin to the front end of the second spiral, which is welded to the pipe.

EFFECT: improving heat transfer of surface of convection pipes, reducing labour input of their manufacture, delivery, erection and repair.

7 cl, 4 dwg

Description

The proposed method relates to a power system and can be used to fin convective pipes in order to increase heat transfer, in tube furnaces, heat exchangers with increased thermal efficiency, in boiler units.

Various designs of heat-exchange elements are known [USSR author's certificate No. 507767, F28F 1/24, 1974; No. 517775, F28F 1/24, 1974; No. 711339, F24F 1/24, 1978; No. 1059412, F28F 1/24, 1982; No. 1673825, F28F 1/24, 1989].

The main disadvantage of these designs is not sufficiently intense heat transfer and the great complexity of their manufacture.

A known method of manufacturing a heat-exchange cylindrical element with transverse ribs having a metal coating on the surface, in order to enhance heat transfer, the coating is made of a material with higher thermal conductivity than the material of the ribs, and has a thickness that is variable in height of the rib (SU 1416849, F28F 1/24, F28F 13/18).

A disadvantage of the known pipes is their lack of thermal efficiency, as a result of which long tubes are required for the possibility of obtaining a compact heat exchanger.

The closest in technical essence to the method is a method of manufacturing a finned convective pipe of a heat exchanger, including the sequential placement of metal disks on the pipe, the inner diameter of which is equal to the nominal diameter of the outer surface of the pipe, fixing them with the pipe by plastic deformation of the latter (SU 634647, 11.26.1978, B21D 37/22).

The specified known method has a high complexity and cannot be applied to already installed pipes.

The technical problem to be solved by the claimed method is aimed at reducing the laboriousness of pipe finning, their repair and delivery to the installation site (since the delivery of a spiral structure and pipes does not require special conditions), increasing the intensity of heat transfer and turbulence of the gas stream in the convection chamber and product in the pipeline.

The problem is solved in that in a method of increasing the heat transfer surface of a convective pipe by fins in a tubular furnace and boiler units, which includes sequential placement of spiral structures (spirals) on the pipe, the inner diameter of which is equal to the diameter of the outer surface of the pipe, lubrication, welding of the front end of the spiral to the pipe, decompression , twisting, connecting with cotter pins to the front end of the next spiral welded to the pipe, etc., as well as the fact that the finning of the pipe is performed by installing a back rales with various section shapes; the inner surface of the spiral (with a given pitch of the ribs of the spiral fixed using a template-retainer) is drilled, ground, and passivated to the diameter of the pipe, while the inner surface of the spiral is lubricated with a special compound to improve sliding and splicing (welding) with it due to the formation of a servo-like film when heating to 500-700 ° C, and when installing the spiral in order to fit snugly to the pipe, it is twisted using a lever (having a cable with a carabiner at the end), hooking 50-100 to the hole of the second end of the spiral gf An oxidized oil base containing serpentinite and manganese oxide is used as a lubricating and welding compound. On the spiral structure, different directions of the turns can be made, the alternation of which on the pipe, as well as pipes having different curling directions, allows to turbulize the gas flow and increase the heat transfer to the heated product.

The list of drawings:

Figure 1 - this figure shows a spiral structure 1 installed inside the template-retainer 3 with a certain step, for subsequent drilling with a drill 5 of the inner surface of the spiral structure 1, the diameter of which is equal to the diameter of the outer surface of the pipe, which will subsequently be made ribbing.

Figure 2 - this figure shows the installation of the spiral structure 1 on the pipe 2 using the lever 6 for tightening.

Figure 3 - this figure depicts a spiral 1 of two types, differing in the curling directions (ribbing clockwise and counterclockwise), which allows to increase heat transfer.

Figure 4 - this figure shows the use of pipes 2 having different directions of curling to increase heat transfer.

According to the proposed method, instead of metal disks, a metal spiral structure (spiral) 1 of a metal of rectangular, round, square, trapezoidal and other sections is installed on the pipe 2, the front end is welded, it is twisted with a step according to the template with a special lever 6 for the second end of the spiral, previously A special lubricant is applied to the inner surface to improve sliding and welding to the pipe due to the formation of a servo film at certain temperatures.

There is the possibility of installing a spiral structure both on newly installed pipes, and on those already installed in tubular furnaces, boiler units, heat exchangers. A big advantage of the proposed method is that the fins are carried out directly at the pipe installation site.

By known methods, the manufacture of finned convective pipes is carried out in the following sequence. Pipes 2 are stacked on the feed rack 3. At the same time, rolls of tape are inserted onto the unwinding devices, the ends of which are tucked into a winding tool. After that, the pipes are subsequently fed into the installation for winding and welding the ribs (in the manufacture of an external spiral transverse finning). The fins 2 perform continuous along the entire length of each pipe.

The manufacture of fins for the installed convective pipe according to the proposed method is carried out in the following sequence.

To obtain a spiriform design by winding, a template tube is used. The template pipe is fed into the installation for winding. A tape of the desired calculated length is wound on it, thereby giving the tape the shape of a pipe on which it will subsequently be installed. The technology of winding the tape onto pipes with a diameter of 20-219 mm was mastered at the enterprises of ZiO-Podolsk, TsNIITMash, etc. The wound spiral structure 1 is removed from the template pipe, placed inside the template-retainer 3 with the rack 4 to give the working position adjacent to the edges of the pipe surface. To do this, they expose with a certain step and drill using a drill 5 with an inner diameter of the spiral 1 equal to the diameter of the outer surface of the pipe 2, grind and passivate (Figure 1). Due to drilling and grinding, the area of contact of the surface of the spiral 1 increases with pipe 2. In the spiral (at the end of the fins), holes are made for twisting the cabin with a special lever 6.

For the convenience of transportation and installation of spirals on the pipe 2, they are made with a size of 400-1000 mm in a compressed state. Two types of spirals are used, distinguished by the curling directions (ribbing clockwise and counterclockwise).

As a material for fins, blanks of rectangular, round, square, trapezoidal, etc. can be used. sections.

Under the conditions of convective pipe operation, for example, in tubular furnaces, in heat exchangers, or in boiler units, with significant temperature differences of the heat carriers on the external and internal surfaces, the spiral structure and pipe are made from materials with the same linear expansion coefficients, or their selection with similar provides added bond strength.

The finning of the pipe is carried out as follows: the inner surface of the spiral structure 1 is lubricated with a special composition containing an oil base and serpentinite, which contributes to the sliding of the spiral along the pipe 2 when twisting with a special lever 6 (Figure 2.), as well as welding of the spiral structure 1 to the pipe 2 behind due to the formation of a servo-like film on the inner surface of the spiral 1 and the outer surface of the pipe 2 under certain heating conditions with a fixed position of the spirals 1 on the pipe. When ribbing, the front end of the spiral 1 is welded to the pipe 2, the pitch of the spiral 1 is set, which is turned by the lever 6 for the second end, which, after tightening, is welded to the pipe 2. The front end of the second spiral is fastened with a cotter pin 7 for the welded second end, tightened by the lever 6 etc. In order to increase heat transfer finned tubes 2 are arranged in a certain sequence along the height of the convection chamber: pipes 2 alternate with right and left turns of the spiral (Figure 3); pipes 2 alternate, on each of which spirals 1 with different directions of turns are installed (Figure 4). This increases the transit time of the flue gases between the pipes, and hence the heat transfer. A convective pipe made by this method provides a total increase in the active heat transfer surface, operational reliability and durability of the connection of the spiral structure with the pipe, reduces the complexity of manufacturing and creates additional turbulization of the coolant flows.

The technical and economic efficiency of the technical solution is expressed in increasing the heat engineering parameters of tube furnaces, heat exchangers, boiler units and in reducing the fuel and energy, manufacturing, manufacturing, installation, repair and transportation costs.

Claims (7)

1. A method of increasing the heat transfer surface of a convective pipe by fins in a tubular furnace and boiler units, comprising sequentially placing spiral structures (spirals) on the pipe, the inner diameter of which is equal to the diameter of the outer surface of the pipe, lubricating, welding the front end of the spiral to the pipe, unloading, twisting, connecting with cotter pins to the front end of the next spiral welded to the pipe, etc. 2. The method according to claim 1, characterized in that the finning of the pipe is performed by installing spirals with various cross-sectional shapes. 3. The method according to claim 1, characterized in that the inner surface of the spiral (with a predetermined pitch of the ribs of the spiral, fixed using a fixing pattern) is drilled, ground, and passivated to the diameter of the pipe. 4. The method according to claim 1, characterized in that the inner surface of the spiral is lubricated with a special composition to improve sliding and splicing (welding) with it due to the formation of a servo-like film when heated to 500-700 ° C. 5. The method according to claim 1, characterized in that when installing the spiral in order to fit snugly to the pipe, it is twisted using a lever (having a cable with a carbine at the end), hooking 50-100 kgf to the hole of the second end of the spiral. 6. The method according to claim 1, characterized in that the oxidized oil base containing serpentinites and manganese oxide is used as a lubricating and welding composition. 7. The method according to claim 1, characterized in that on the spiral structure perform different directions of the turns, the alternation of which on the pipe, as well as pipes having different directions of curling, allows to turbulize the gas flow and increase the heat transfer to the heated product.

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