CN86104136A - Titanium-aluminum composite fin tube and manufacturing process - Google Patents

Abstract

Heat exchanger titanium-Al bimetal composite fin tube and manufacturing process thereof, internal layer is the titanium pipe, skin is an aluminum finned tube, titanium-aluminium composite pipe the base that makes with cold-drawing process, through 200-400 ℃, 1～2 hour vacuum heat, with the mill milling fin that the different-diameter blade is housed on the roll, 80～86 millimeters of blade diameters, several 9～23 crust of blade, corrosion resisting property with the same good heat-conducting of copper-aluminum composite fin tube and pure titanium can be used as the heat transfer element of the heat exchanger that uses Korrosionsmedium, prolongs heat exchanger service life.

Description

The invention belongs to composite bimetal pipe.

Domestic coastal power plant generally adopts the heat transfer element of copper-aluminum composite fin tube as aerial cooler at present.This pipe has the good heat transfer characteristic, but internal layer brass is in the cooling water medium (routine seawater) that pollutes, owing to stress corrosion produces cracking, leaks, service life is shorter, according to investigations, three, four years pipes of general use promptly begin to leak, serious use once, begin to leak (1) after 2 years, industrially pure titanium has excellent corrosion resistant performance, abroad, obtain extensive use in fields such as oil, chemical industry, also adopt titanium pipe (2) in a large number in some power plant salt water cooling systems of states such as Japan and the United States, but the price of pure titanium pipe is more expensive.

The manufacture method of composite bimetal pipe has: rolling and hubbing, rolling is because the deviation of the downforce of roll and pipe thickness and cause that easily body length direction composite force is inhomogeneous, in general, even improving the downforce of roll, the roll forming method can not obtain sufficient composite force, hubbing will be obtained relatively difficulty of very high composite force, but composite force is more even, and is stable.It is compressive residual stress can not be stayed in the multiple tube that two kinds of methods have a common drawback, so composite force can not be retained under the higher compression for a long time, just obviously descends in its composite force of the rolling back of fin like this.

The purpose of this invention is to provide a kind of heat exchanger bimetallic composite fin tube, it had both had the such good heat transfer characteristic of copper-aluminum finned tube, the good corrosion resistance of titanium material is arranged again, and manufacturing cost was more cheap than pure titanium pipe; Another object of the present invention is the manufacturing process that proposes a kind of bimetallic composite fin tube that is made of the bigger two kinds of metals (titanium-aluminium) of difference of thermal expansion coefficients, adopt this technology, composite bed can keep higher composite force, thereby has the good heat transfer characteristic.

The present invention is a kind of composite bimetal pipe, and by internal layer titanium pipe, outer aluminous fin pipe constitutes.Make heat exchanger heat transfer element usefulness, its essence is that internal layer is the good titanium pipe of corrosion resistance, thus this heat transfer element be used for polluting cooling medium the time do not produce because the cracking that causes of stress corrosion, leakage phenomenon can increase the service life.

The present invention proposes a kind of manufacturing process of titanium-aluminum composite fin tube, and its technological process is: Incoming Quality Control-aluminum pipe is taken the lead-is cleaned-alignment-cold-drawn-compound-crop-cleaning-annealing-alignment-rolled fin-cleaning-scale-packing.

The essence of this technology is to make composite interface keep high composite force, thereby reduces the thermal resistance of composite bed, improves the heat transfer efficiency of heat transfer element, and its key measure is:

(1) the composite pipe blank heat treatment of before rolled fin, annealing, heat-treat condition:

Temperature 200-400 ℃, the time: 1～2 hour.

(2) adopt the mill milling fin that the blade of various outer diameter is housed on the roll, by adjusting blade external diameter and angle, the blade of various outer diameter produces different linear velocities, makes composite pipe blank be subjected to additional " distortion " stress.Thereby avoid the decline of composite pipe blank composite force when rolling wing, the roll number is 3, and blade is several 9～23, blade external diameter 80-66 millimeter.

Invention is described in detail as follows:

Titanium-aluminum composite fin tube:

Fig. 1 is titanium-aluminum composite fin tube, longitudinal section.

By internal layer titanium pipe 1, outer aluminum finned tube 2 constitutes.

Titanium-aluminum composite fin tube manufacturing process (in turn) by manufacturing process:

1, Incoming Quality Control: titanium pipe quality should meet " condenser pipe seamless titanium tube " national standard requirement, and tube surfaces does not have serious scratch, scuffing; Aluminum tube surfaces, loose, crackle must not be arranged when observing under the low power metallographic microscope, subtract layer, the tail that contracts, slag inclusion, and intermetallic compound and thick bright crystallization, in order to avoid fin produces phenomenons such as cracking, the aluminum pipe external diameter is derived by experience before compound, and is general than the big 10-15% of aluminum pipe sectional area after compound.

2, aluminum pipe is taken the lead, and dials clamp for drawing.

3, compound firm for guaranteeing, titanium pipe and aluminum pipe composite surface are answered free from dust and greasy dirt, use Y _B-5 cleaning agents are mixed with 5% aqueous solution and clean, and rinse well in 60 ℃ of water immediately then.

4, straightener alignment.

5, the synthetic titanium of cold-drawing recovery-aluminium composite pipe base on general drawbench, the external diameter section reduction rate of aluminum pipe and titanium pipe is respectively 11-15% and 1-3%, recombination velocity during drawing: 4-10 rice/minute, lubricant: steam cylinder oil.

6, composite pipe blank crop, cleaning

7, composite pipe blank annealing heat treatment: this operation is to make finned tube have one of key measure of high composite force, be that effect is 1. to eliminate grain growth in the Cold Drawing Process, avoid multiple tube obviously to descend because of the composite force that aging phenomenon produces, 2. pipe (titanium) has bigger processing resilience characteristics in utilizing, improve the composite force of composite bed, heat-treat condition: temperature 200-400 ℃, 1～2 hour time, vacuum atmosphere

8, pipe alignment

9, rolled fin: this operation is one of key of titanium-aluminum composite fin tube manufacturing process, and fin is rolling to carry out on cold-rolling mill, and the different blade of diameter is housed on each roll, and Fig. 2 is a three-high mill rolled fin schematic diagram.Equipment is supplied with by power motor, pass to three rolls of 120 ° each other through speed change, three groups of blades are housed on the roll, and composite pipe blank is subjected to the effect of insert tangential power and screw, along with blade is pressed into gradually, force metal to enter mecystasis, and forcing metal upwards to flow along the two side faces of blade, the design of blade is that deflection progressively is distributed on each blade, so pipe for the helical movement advancing under the roll effect, through set of blades, promptly form the desired fin of product.

Roll the principal element that wing is shaped: the friction system of (1) blade and Metal Contact, when lack of lubrication or blade fineness are relatively poor when rolling, metal increases to the high direction flow resistance of wing, cause the top layer of metal that tangible stagnant zone is arranged, thereby make the rolling deficiency of fin height, profile is polygon, and serious situation can make composite bed loose fully.For this reason, the pipe surface should be coated with lubricating grease, and uses the oil emulsion cooling and lubricating, guarantees blade fineness △ simultaneously.More than; (2) adjustment of rolling blade: make pipe when progressively the roll forming blade is in adjustment behind the process roll, corresponding same blade will be adjusted on same the helix on three rolls, its pitch should be consistent with finned tube pitch, and three roll centers should same partially angle with respect to center line, the numerical value of this angle should with the helical angle consistent (approximate mark method) in footpath in the finned tube, each is organized gap blade and should be consistent, thereby guarantees that the pipe helical angle is calculated as follows:

tgα＝ (t)/(πD ₂) ，

Alpha-helix angle in the formula, t-pitch, D ₂Footpath in the-finned tube; (3) tube blank size: the pipe external diameter determines that by product specification according to plastic deformation constancy of volume principle, the pipe external diameter can be calculated as follows before rolling:

$\mathrm{d\; =}\sqrt{\frac{V}{\mathrm{t\; \times }\frac{\pi }{4}}{\mathrm{+<figure-callout\; id="2"\; label="D"\; filenames="86104136\_DRIMG1.png"\; state="\{\{state\}\}">D</figure-callout>}}^2{}_1\mathrm{\times (1\; +\; \mu \; )}}$

In the formula: d-pipe external diameter, D ₁Footpath at the bottom of the-product fin, V-fin volume,

The t-pitch of fin, μ-lengthening coefficient.

V＝ (πh)/4 〔2（B+b）D ₁+ 8/3 hB+ 4/3 hb〕+πr ²D ₁（2- (π)/2 ）

H-fin height in the formula, B-fin root width,

B-fin top width, r-fin root garden arc radius.

10, last, finned tube is through cleaning, scale, packing.

With titanium-aluminum composite fin tube that this technology is made, do the anticorrosion stress-resistant test with the Qinshan polluted seawater, through constant load, the permanent distortion and slow strain rate test two months, stress corrosion does not take place, the stress corrosion (cracking) test condition:

Medium composition: original Qinshan seawater (Cl

5996PPM, PH8.37,

Conductance: 16.0 * 10 ³MV/cm), add NaCl, NaS, NH again ₄Cl is mixed with and contains NaCl 3.5%, S.1Mg/L, and NH ⁺ ₄The 2mg/L aqueous solution, final PH=7.6; Test temperature: 50 ℃ (wick test sample, surface temperature are 100 ± 10 ℃), test method: laterally afterburning.

Under the identical condition of finned tube physical dimension, cold fluid and hot fluid condition, titanium-aluminum composite fin tube and copper-aluminum composite fin tube have been made the heat-transfer character contrast test, test shows: titanium-aluminum finned tube has the same good heat transfer characteristic of copper-aluminum finned tube.

The heat-transfer character contrast test

Titanium-aluminum composite fin tube copper-aluminum composite fin tube

Ribbed pipe external diameter (millimeter) 43.93 43.38

Parent tube external diameter (millimeter) 24.73 24.94

Inner tube diameter (millimeter) 19.1 18.44

Aluminum pipe wall thickness (millimeter) 2.02 2.25

Thick (millimeter) 0.8 1.0 of inner tubal wall

Composite force (kg/cm ²) 50 16

Heat transfer coefficient-Kl 17.5u ^0.48 _∞15.5u ^0.48 _∞

Shanghai Electric Machine Plant of production unit Shanghai Non-Standard Steel Pipe Plant

Test specimen length: 582 millimeters, average fin is thick: 0.45 millimeter, and spacing of fin:

2.5 millimeter.

This titanium-aluminum composite fin tube is used for the power station cooler, and the interior pipe cracking that can avoid stress corrosion to produce leaks, and not only can guarantee safe power generation, and can save a large amount of expenses such as stopping production, replace tubes, maintenance and time.Also can be used as the heat exchanger heat transfer element.Be used for fields such as oil, chemical industry, boats and ships.

Description of drawings:

Fig. 1 is titanium-aluminum composite fin tube longitudinal section

1-internal layer titanium pipe wherein, the outer aluminum finned tube of 2-

Fig. 2 is a three-high mill rolled fin schematic diagram.Wherein, the 3-composite pipe blank,

The 4-roll mandrel, 5-blade, 6, finned tube, 7-key.

Embodiment:

Interior pipe titanium pipe (AT ₂), external diameter φ 21mm, wall thickness 0.8mm, outer tube aluminum pipe (L ₂), external diameter φ 33mm, wall thickness 5mm, aluminum pipe is taken the lead, and is with after aluminum pipe, the cleaning of titanium pipe, the alignment, cold drawn compound on drawbench then, drawing speed: 6 meters/minute.

Mould aperture: φ 31mm passage: 1 time

Obtain titanium-aluminium composite pipe base, external diameter is 31mm, and through crop, after the cleaning, in vacuum furnace annealing heat treatment, 300 ℃ are incubated 1 hour, and this moment, the composite force of composite pipe blank was 173kg/cm ², after alignment, on three roller roller machines, roll wing, 23 every group on rolling blade, the blade external diameter: φ 80～86mm finally obtains the finned tube size: external diameter 44mm, the high 10mm of wing, wing be apart from 2.5mm, endoporus 19.4mm, composite force: 143kg/cm ²

Claims (5)

1, a kind of composite bimetal pipe, skin is the aluminous fin pipe, it is characterized in that internal layer is the titanium pipe.

2, the manufacturing process of the compound finned tube of titanium-aluminium comprises Incoming Quality Control, and aluminum pipe is taken the lead, cleaning, alignment, cold-drawn are compound, and crop, scale is characterized in that:

(1) the composite pipe blank heat treatment of before rolled fin, annealing, heat-treat condition is:

Temperature 200-400 ℃, 1～2 hour time.

(2) adopt the mill milling fin that the blade of various outer diameter is housed on the roll.

3, according to the described technology of claim 2, the roll number is 3.

4, according to claim 2 or 3 described technologies, be equipped with 9～23 blade on each roll.

5, according to claim 2 or 3 or 4 described technologies, the external diameter of blade is 80～86 millimeters.

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