CN113465439A

CN113465439A - Method for heat exchange tube anticorrosion treatment, heat exchanger and water heater

Info

Publication number: CN113465439A
Application number: CN202010242242.7A
Authority: CN
Inventors: 李超; 董玮利; 杨少强; 李小娇; 王秀萍
Original assignee: Qingdao Haier Smart Technology R&D Co Ltd; Haier Smart Home Co Ltd
Current assignee: Qingdao Haier Smart Technology R&D Co Ltd; Haier Smart Home Co Ltd
Priority date: 2020-03-31
Filing date: 2020-03-31
Publication date: 2021-10-01

Abstract

The application relates to the technical field of water heaters, and discloses a method for the anticorrosion treatment of a heat exchange tube, which comprises the following steps: after the heat exchange tube is pretreated, injecting a first plating solution into the inner wall of the heat exchange tube, and forming an electroplated layer through electroplating treatment; injecting a second plating solution into the heat exchange tube through a circulating pump, and performing chemical plating treatment on the basis of the electroplated layer to form an anticorrosive plated layer; and injecting sealing liquid into the heat exchange tube, and performing air drying and curing treatment to form a sealing layer. The method for the heat exchange tube anticorrosion treatment can form the anticorrosion coating and the sealing layer on the surface of the inner wall of the heat exchange tube, the anticorrosion effect of the heat exchange tube is improved by combining the anticorrosion coating and the sealing layer, the service life of the heat exchange tube can be effectively prolonged, and the service life of the heat exchange tube is not less than the scrapped age of the heat exchanger. The application also discloses a heat exchanger and water heater.

Description

Method for heat exchange tube anticorrosion treatment, heat exchanger and water heater

Technical Field

The application relates to the technical field of water heaters, for example, to a method for performing anticorrosion treatment on a heat exchange tube, a heat exchanger and a water heater.

Background

At present, in order to improve the heat conduction performance of a heat exchanger, heat exchange tubes made of metal materials are adopted, due to the characteristics of cost factors and materials, most of heat exchange tubes can be corroded by water after being contacted with the water for a long time, particularly, the corrosion process of the metal can be accelerated for water with more impurities, so that the heat exchange tubes are leaked, and the heat exchanger needs to be replaced frequently.

In addition, different fields are for guaranteeing the security of using the gas heater, are equipped with the scrap age to gas heater. The prior art provides an anti-corrosion method for electroplating, painting, passivation and the like, and aims to improve the anti-corrosion performance of a heat exchange tube so as to ensure that the service life of the heat exchange tube is not lower than the scrapped age.

In the process of implementing the embodiments of the present disclosure, it is found that at least the following problems exist in the related art:

for the situation of serious water pollution, the corrosion prevention method in the prior art can not effectively prevent the corrosion of the heat exchange tube for a long time.

Disclosure of Invention

The following presents a simplified summary in order to provide a basic understanding of some aspects of the disclosed embodiments. This summary is not an extensive overview nor is intended to identify key/critical elements or to delineate the scope of such embodiments but rather as a prelude to the more detailed description that is presented later.

The embodiment of the disclosure provides a method for performing anticorrosion treatment on a heat exchange tube, a heat exchanger and a water heater, and aims to solve the technical problem that an anticorrosion method in the prior art cannot effectively prevent corrosion of the heat exchange tube for a long time under the condition of serious water pollution.

In some embodiments, the method comprises:

after the heat exchange tube is pretreated, injecting a first plating solution into the inner wall of the heat exchange tube, and forming an electroplated layer through electroplating treatment;

injecting a second plating solution into the heat exchange tube through a circulating pump, and performing chemical plating treatment on the basis of the electroplated layer to form an anticorrosive plated layer;

and injecting sealing liquid into the heat exchange tube, and performing air drying and curing treatment to form a sealing layer.

In some embodiments, the heat exchanger comprises a heat exchange tube, and the inner wall surface of the heat exchange tube comprises an anti-corrosion coating and a sealing layer formed according to the method.

In some embodiments, the water heater includes the heat exchanger described above.

The method for the heat exchange tube anticorrosion treatment, the heat exchanger and the water heater provided by the embodiment of the disclosure can realize the following technical effects:

the method for the heat exchange tube anticorrosion treatment can form the anticorrosion coating and the sealing layer on the surface of the inner wall of the heat exchange tube, the anticorrosion effect of the heat exchange tube is improved by combining the anticorrosion coating and the sealing layer, the service life of the heat exchange tube can be effectively prolonged, and the service life of the heat exchange tube is not less than the scrapped age of the heat exchanger.

The foregoing general description and the following description are exemplary and explanatory only and are not restrictive of the application.

Drawings

One or more embodiments are illustrated by way of example in the accompanying drawings, which correspond to the accompanying drawings and not in limitation thereof, in which elements having the same reference numeral designations are shown as like elements and not in limitation thereof, and wherein:

FIG. 1 is a schematic diagram of a method for corrosion protection treatment of heat exchange tubes provided by an embodiment of the present disclosure;

FIG. 2a is a schematic view of a heat exchanger according to an embodiment of the present disclosure;

FIG. 2b is a schematic view of another heat exchanger according to an embodiment of the present disclosure;

FIG. 2c is a schematic view of another heat exchanger according to an embodiment of the present disclosure;

FIG. 3 is a schematic cross-sectional view of a heat exchange tube provided by an embodiment of the present disclosure;

FIG. 4a is a graph showing the results of an open circuit potential test during an electrochemical test provided by an embodiment of the present disclosure;

FIG. 4b is the result of an open circuit potential test during another electrochemical test provided by embodiments of the present disclosure;

FIG. 5a is the results of a polarization curve test and fitting provided by embodiments of the present disclosure;

fig. 5b is the result of another polarization curve test and fitting provided by embodiments of the present disclosure.

Detailed Description

So that the manner in which the features and elements of the disclosed embodiments can be understood in detail, a more particular description of the disclosed embodiments, briefly summarized above, may be had by reference to the embodiments, some of which are illustrated in the appended drawings. In the following description of the technology, for purposes of explanation, numerous details are set forth in order to provide a thorough understanding of the disclosed embodiments. However, one or more embodiments may be practiced without these details. In other instances, well-known structures and devices may be shown in simplified form in order to simplify the drawing.

The terms "first," "second," and the like in the description and in the claims, and the above-described drawings of embodiments of the present disclosure, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It should be understood that the data so used may be interchanged under appropriate circumstances such that embodiments of the present disclosure described herein may be made. Furthermore, the terms "comprising" and "having," as well as any variations thereof, are intended to cover non-exclusive inclusions.

The term "plurality" means two or more unless otherwise specified.

In the embodiment of the present disclosure, the character "/" indicates that the preceding and following objects are in an or relationship. For example, A/B represents: a or B.

The term "and/or" is an associative relationship that describes objects, meaning that three relationships may exist. For example, a and/or B, represents: a or B, or A and B.

The anticorrosion treatment method provided by the embodiment of the disclosure can be suitable for anticorrosion treatment of metal pieces in different fields. Because the heat exchange tube is in the course of the work, the heat exchange tube inner wall contacts with heat transfer solution for a long time, the probability of being corroded is great, and heat transfer solution temperature is higher, and the corrosion rate is faster, therefore, this application explains the step of anticorrosive treatment method with the inner wall to the heat exchange tube as an example, for the life of extension heat exchange tube, can also utilize the method that this application provided to carry out anticorrosive treatment to the outer wall of heat exchange tube, the outer wall anticorrosive treatment does not seal or select high temperature resistant sealant.

Fig. 1 is a schematic diagram of a method for corrosion protection treatment of a heat exchange pipe according to an embodiment of the present disclosure, and as shown in the drawing, the method includes the following steps:

s101, preprocessing the heat exchange pipe.

In order to improve the effectiveness of the heat exchange pipe anticorrosion treatment, the surface of the heat exchange pipe is pretreated before the heat exchange pipe is subjected to the anticorrosion treatment, so that the surface of the heat exchange pipe is clean and free of impurities.

In some embodiments, the pre-processing comprises: oil removal treatment and acid pickling treatment.

In some embodiments, the degreasing treatment comprises: determining oil removal time; injecting a degreasing agent into the inner wall of the heat exchange pipe according to the degreasing time; and (4) leading out the degreasing agent and injecting deionized water for washing so as to clean the degreasing agent remained on the inner wall of the heat exchange tube.

In some embodiments, the oil removal time may be set to 1-30 min. Optionally, the oil removal time is 1min, 5min, 10min, 15min, 20min, 25min or 30 min. The oil removing time is determined according to the oil stain condition of the inner wall of the heat exchange tube and the type and concentration of the oil removing agent. The more serious the oil stain condition on the inner wall of the heat exchange tube, the longer the oil removing time. When the type of the oil removing agent is determined, the oil removing time is shorter as the concentration is higher.

In some embodiments, the degreaser temperature ranges from 30 to 80 ℃, optionally 30 ℃, 35 ℃, 40 ℃, 45 ℃, 50 ℃, 55 ℃, 60 ℃, 65 ℃, 70 ℃, 75 ℃ or 80 ℃. Wherein, the temperature of the oil removing agent is determined according to the type and the concentration of the oil removing agent so as to improve the oil removing effect.

In different embodiments, the degreasing agent can be injected into the inner wall of the heat exchange tube in various ways. Optionally, the method of injecting the oil removing agent includes: pumped by a power device, guided by gravity and soaked in the whole machine.

In some embodiments, the method is used for performing anti-corrosion treatment on the outer wall of the heat exchange pipe, and a complete machine soaking mode can be directly selected.

In some embodiments, the method is used for performing anti-corrosion treatment on the inner wall of the heat exchange pipe, and a pumping mode through a power device or a power gravity leading-in mode is selected. The mode of pumping in through power device or leading-in degreaser through gravity can guarantee that degreaser fully contacts the heat exchange tube inner wall, improves deoiling speed, reduces the quantity of degreaser than the mode that the complete machine soaked.

In some embodiments, the flow rate of the degreasing agent is 0.2-2 m/s when the degreasing agent is pumped by a power device or injected by a gravity introduction mode. Optionally, the flow rate of the oil removing agent is 0.2m/s, 0.5m/s, 1m/s, 1.5m/s or 2 m/s. Wherein, the flow rate of the oil removing agent is determined according to the type and the concentration of the oil removing agent. When the type of the degreasing agent is determined, the higher the concentration is, the smaller the flow velocity is, so as to avoid scouring corrosion caused by the overlarge flow velocity of the degreasing agent.

In some embodiments, to improve the efficiency of the degreasing process, the flow rate is dynamically varied during the degreasing process, and the flow rate of the degreasing agent is gradually decreased as the degreasing process progresses. Along with the going on of deoiling process, the heat exchange tube inner wall greasy dirt reduces, then reduces the velocity of flow gradually and avoids causing the erosion and corrosion when the velocity of flow is too big.

In one embodiment, the oil remover is an alkali liquid oil remover, and the oil remover comprises the following components: 10-20 g/L of sodium carbonate, 10-20 g/L of trisodium phosphate, 10-20 g/L of sodium silicate and 2-3 g/L of OP emulsifier, and the temperature of the degreasing agent is 70 ℃. The pumping or introducing mode can be selected for injecting the degreasing agent, the flow rate is controlled to be less than or equal to 2m/s, the degreasing time is controlled to be 1-30 min, and the degreasing agent is specifically adjusted according to the oil stain condition on the inner wall of the heat exchange tube.

In some embodiments, the acid wash treatment comprises: determining the pickling time; injecting a pickling agent into the inner wall of the heat exchange pipe according to the pickling time; and leading out the pickling agent and injecting deionized water for washing so as to clean the residual pickling agent on the inner wall of the heat exchange tube. The acid washing treatment aims to remove oxide skin and corrosion products on the inner wall of the heat exchange tube, so that the inner wall of the heat exchange tube is in an activated state, and the good adhesion between a coating and the heat exchange tube in the subsequent electroplating process is facilitated.

In different embodiments, the pickling agent is injected into the inner wall of the heat exchange tube in various ways. Optionally, the manner of injecting the pickling agent includes: pumped by a power device, guided by gravity and soaked in the whole machine.

In some embodiments, the whole machine soaking mode can be directly selected for the anticorrosion treatment of the outer wall of the heat exchange pipe.

In some embodiments, the flow rate of the pickling agent is 0.2-2 m/s when the pickling agent is pumped by a power plant or injected by gravity introduction. Optionally, the flow rate of the pickling agent is 0.2m/s, 0.5m/s, 1m/s, 1.5m/s or 2 m/s. Wherein the flow rate of the pickling agent is determined according to the type and concentration of the pickling agent. When the type of the pickling agent is determined, the flow rate is smaller when the concentration is larger, so that the scouring corrosion caused by the overlarge flow rate of the pickling agent is avoided.

In some embodiments, the pickling time is determined according to the type and concentration of the pickling agent, and is adjusted according to the condition of attachments on the inner wall of the heat exchange tube after oil removal. When the type of pickling agent is determined, the pickling time is shortened as the concentration is increased. In some embodiments, the acid washing time may be set to 1 to 10 min. Optionally, the pickling time is 1min, 2min, 4min, 6min, 8min or 10 min.

In some embodiments, the pickling agent temperature ranges from 20 ℃ to 70 ℃, optionally 20 ℃, 25 ℃, 30 ℃, 45 ℃, 40 ℃, 45 ℃, 50 ℃, 55 ℃, 60 ℃, 65 ℃ or 70 ℃. Wherein, the temperature of the pickling agent is determined according to the type and concentration of the pickling agent so as to improve the pickling effect.

In one embodiment, the acid wash is an acidic solution comprising the following components: 170mL/L of hydrochloric acid, 80mL/L of sulfuric acid, 3g/L of hexamethylenetetramine and 100g/L of sodium chloride, and the temperature of the acid washing agent is 60 ℃. The mode of injecting the pickling agent can be selected to be a pumping or introducing mode, the flow rate is controlled to be less than or equal to 2m/s, the pickling time is controlled to be 1-10 min, and the pickling time is specifically adjusted according to the condition of attachments on the inner wall of the heat exchange tube after oil removal.

In some embodiments, injecting a pickling agent into the inner wall of the heat exchange tube according to the pickling time comprises: determining a first pickling time and a second pickling time according to the components of the pickling time, the first pickling agent and the second pickling agent; injecting a first pickling agent into the inner wall of the heat exchange tube according to the first pickling time; and injecting a second acid cleaning agent into the inner wall of the heat exchange tube according to the second acid cleaning time. Wherein, the first acid washing agent is a reducing acid solution, and the second acid washing agent is an oxidizing acid solution.

In some embodiments, before injecting the second acid washing agent into the inner wall of the heat exchange tube according to the second acid washing time, the method further comprises: the first pickling agent is led out and injected with deionized water for washing so as to clean the first pickling agent remained on the inner wall of the heat exchange tube and improve the pickling efficiency.

S102, injecting a first plating solution into the inner wall of the heat exchange tube, and forming an electroplated layer through electroplating treatment.

In some embodiments, the electroplating process comprises: determining the electroplating time and the set current; the heat exchange tube is used as a cathode, the nickel wire is used as an anode, and the heat exchange tube is electroplated according to the set current and the electroplating duration.

In some embodiments, the first plating solution is an acidic nickel salt solution.

In some embodiments, the composition of the acidic nickel salt solution comprises: 240g/L of nickel chloride hexahydrate and 320mL/L of 30% hydrochloric acid.

In some embodiments, the plating time is 3 to 5 seconds. Optionally, the plating time is 3s, 3.5s, 4s, 4.5s or 5 s. The electroplating aims to perform pre-plating operation for subsequent chemical plating to form a very thin nickel layer, and the growth of a nickel-phosphorus coating is realized through the autocatalysis effect of the chemical plating, so the electroplating time is not suitable to be too long.

In one embodiment, the acidic nickel salt solution comprises the following components: 240g/L of nickel chloride hexahydrate and 320mL/L of 30% hydrochloric acid, and the set current is 1-10A/dm²And the electroplating time is controlled within 3-5 s, and is determined according to the anti-corrosion requirement of the heat exchange tube.

In some embodiments, after the plating process forms the plating layer, the method further includes: and leading out the first plating solution and injecting deionized water for washing so as to clean the first plating solution remained on the inner wall of the heat exchange tube.

S103, injecting a second plating solution into the heat exchange tube through a circulating pump, and performing chemical plating treatment on the basis of the electroplated layer to form an anticorrosive plated layer.

In some embodiments, the electroless plating process comprises: determining the chemical plating time length and the flow rate of a circulating pump; and controlling the circulating pump to work according to the chemical plating time and the circulating pump flow rate.

In some embodiments, the electroless plating time is 30-60 min. Optionally, the chemical plating time is 30min, 35min, 40min, 45min, 50min, 55min or 60 min. Because the chemical plating time is long, the second plating solution is continuously injected into the heat exchange tube through the circulating pump, and the temperature of the second plating solution can be controlled to be relatively stable in the chemical plating treatment process.

In some embodiments, the circulation pump flow rate is 1 to 100 mm/s. Alternatively, the circulation pump flow rate is 10mm/s, 20mm/s, 30mm/s, 40mm/s, 50mm/s, 60mm/s, 70mm/s, 80mm/s, 90mm/s or 100 mm/s. Wherein, the flow rate of the circulating pump is determined according to the type and the concentration of the second plating solution. When the type of the second plating solution is determined, the smaller the concentration is, the smaller the flow speed of the circulating pump is, so as to ensure that the plating solution is effectively attached to the inner wall of the heat exchange tube, the growth speed of the nickel-phosphorus plating layer meets the anti-corrosion requirement within a limited time period, and the anti-corrosion plating layer reaches the ideal thickness after the chemical plating is finished. When the second plating liquid type is determined, the larger the concentration is, the stronger the adhesion ability is, the larger the acceptable range of the flow rate for the circulation pump is as compared with the solution having the smaller concentration.

In some embodiments, the second plating solution temperature is in a range of 80-95 ℃. Optionally, the temperature of the second plating solution is 80 ℃, 85 ℃, 90 ℃ or 95 ℃.

In some embodiments, the second plating solution comprises: nickel salts, dihydrogen phosphate, citrate, molybdate and acetate. In some embodiments, the second plating solution also includes other components commonly used in electroless plating solutions.

In some embodiments, the electroless plating process comprises: determining the chemical plating time length, the flow rate of a circulating pump and the swing period; and controlling the circulation pump to work according to the chemical plating time and the circulation pump flow rate, and adjusting the position of the heat exchange tube according to the swing period.

Fig. 2a, 2b and 2c are schematic diagrams of the heat exchanger provided by the embodiment of the disclosure in different placement positions, and as shown in the drawings, the heat exchange tube is a coiled tube.

During the chemical plating treatment, hydrogen is generated along with the growth of the coating, and if the position of the heat exchanger is kept unchanged, the hydrogen can be gathered at the bent part of the heat exchange tube to inhibit the growth of the coating, so that the position of the heat exchanger needs to be adjusted to avoid the gathering of the hydrogen. Because the circulating pump is required to continuously inject the second plating solution into the heat exchange tube in the chemical plating process, the position of the heat exchanger is not suitable to be continuously or frequently changed, and the position of the heat exchange tube is adjusted according to the set swing period. Optionally, the swing period is 1-5 min. Optionally, the swing period is 1min, 2min, 3min, 4min or 5 min.

In some embodiments, adjusting the position of the heat exchange tube according to the period of oscillation comprises: determining two or more setting angles; and controlling the heat exchange tube to maintain different setting angles in adjacent swing periods.

Optionally, three or four swing angles are selected.

In some embodiments, when four swing angles are selected, the swing angles are 45 °, 135 °, 225 °, and 315 ° in sequence with a certain point as an origin, and the time for maintaining the stable state after changing the swing angle is a set swing period.

In some embodiments, when three swing angles are selected, the first swing angle is 5 ° to 30 °, the second swing angle is 95 ° to 120 °, and the third swing angle is 330 ° to 355 ° with a certain point as an origin. And selecting an angle from the three set angle ranges, controlling the heat exchanger to be placed at a certain angle of the three angles in different swing periods, and controlling the angles in adjacent periods to be different.

In a specific embodiment, as shown in fig. 2a, the first swing angle is 5 °, as shown in fig. 2b, the second swing angle is 95 °, as shown in fig. 2c, the third swing angle is 355 °, and within the swing period, 2min, during the anti-corrosion treatment, the heat exchanger is rotated clockwise to the first swing angle of 5 °, and maintained at the first swing angle for 2min, then rotated clockwise to the second swing angle of 95 °, and maintained at the second swing angle for 2min, and then rotated clockwise to the third swing angle of 355 °, and maintained at the third swing angle for 2min, so as to circulate, and the heat exchanger position is adjusted by the first swing angle, the second swing angle, and the third swing angle after every 2 min.

In some embodiments, after forming the anticorrosive coating layer by performing an electroless plating treatment based on the plating layer, the method further includes: and leading out the second plating solution and injecting deionized water for washing so as to clean the second plating solution remained on the inner wall of the heat exchange tube.

In some embodiments, after the water washing, further comprising: and carrying out air drying treatment on the heat exchange pipe.

In some embodiments, the seasoning process comprises: determining the air drying temperature; and blowing air into the heat exchange tube according to the air drying temperature so as to improve the drying rate.

And S104, injecting sealing liquid into the heat exchange tube, and performing air drying and curing treatment to form a sealing layer.

In some embodiments, the confining liquid comprises: water-based resin, silane coupling agent and surfactant.

In one embodiment, the sealant fluid is an aqueous sealant fluid comprising the following components: 4-8 g/L of polyurethane resin, 2-4 g/L of surfactant and 0.5-2 g/L of silane coupling agent, wherein the surfactant is surfactant OP-5.

The method for the heat exchange tube anticorrosion treatment provided by the embodiment of the disclosure can form the anticorrosion coating and the sealing layer on the surface of the inner wall of the heat exchange tube, the anticorrosion effect of the heat exchange tube is improved by adopting the mode of combining the anticorrosion coating and the sealing layer, the service life of the heat exchange tube can be effectively prolonged, and the service life of the heat exchange tube is ensured to be not less than the scrapped age of the heat exchanger.

The embodiment of the disclosure also discloses a heat exchanger, which comprises a heat exchange tube, wherein the surface of the inner wall of the heat exchange tube comprises an anti-corrosion coating and a sealing layer formed by the method provided by the embodiment.

In some embodiments, the thickness of the corrosion protection coating is greater than the thickness of the seal layer.

In some embodiments, the thickness of the anti-corrosion coating is 5-10 μm; the thickness of the sealing layer is 1-3 μm. The seal coat can show and promote cladding material corrosion resistance, and thickness is less can not influence the heat transfer rate of heat exchange tube.

The embodiment of the disclosure also discloses a heat exchanger, and the water heater comprises the heat exchanger.

Fig. 3 is a schematic cross-sectional view of a heat exchange tube provided in an embodiment of the present disclosure, which is corrosion-protected according to the method provided in the above embodiment. As shown in the figure, the heat exchange tube includes: the heat exchange tube comprises a heat exchange tube substrate 1, an anticorrosive coating 2 and a sealing layer 3. In the disclosed embodiment, the anti-corrosion coating 2 is a nickel-phosphorus coating.

The combined structure of the anti-corrosion coating layer 2 and the sealing layer 3 can implement multiple anti-corrosion protection for the heat exchange tube, thereby realizing the purpose of prolonging the service life of the heat exchange tube. The anti-corrosion coating 2 is arranged on the inner side of the heat exchange tube substrate 1, has a barrier effect on a corrosion medium (such as a heat exchange solution in a heat exchange tube), and inhibits the corrosion medium from contacting with the heat exchange tube substrate 1. Meanwhile, in a corrosion medium contacted with the heat exchange tube, the open circuit potential of the anti-corrosion coating 2 is lower than that of the heat exchange tube substrate 1, and the anti-corrosion coating has a sacrificial anode effect relative to the heat exchange tube substrate 1, so that even if the corrosion medium is contacted with the heat exchange tube substrate 1 through the anti-corrosion coating 2, electrons can be provided for the heat exchange tube substrate 1 by accelerating the self corrosion of the anti-corrosion coating 2, and the heat exchange tube substrate 1 is protected from being corroded.

The anti-corrosion coating 2 formed by the method provided by the embodiment is of an amorphous structure, does not have crystal boundaries and crystal grains, can avoid forming microcosmic couples, has better corrosion resistance in a normal-temperature neutral solution, but the corrosion rate of the anti-corrosion coating 2 in a high-temperature heat exchange solution is rapidly increased.

Furthermore, a sealing layer 3 is arranged on the inner side of the anti-corrosion coating 2, and the sealing layer 3 is directly contacted with a corrosive medium. Because anticorrosive coating 2 inevitably has certain hole, a small amount of corrosion medium can see through hole and the contact of heat exchange tube substrate 1, and seal layer 3 can seal these holes, has promoted anticorrosive coating 2 and has promoted the separation effect to corrosion medium, and the suppression corrodes medium and contacts with anticorrosive coating 2, plays the corrosion protection effect to anticorrosive coating 2, has increased the one deck protective layer for heat exchange tube substrate 1, is favorable to prolonging heat exchange tube life-span.

In a specific embodiment, two heat exchange tube samples are prepared by the prior art and the method for the heat exchange tube anticorrosion treatment provided by the above embodiment, and the first heat exchange tube structure includes: substrate and nickel phosphorus cladding material, second kind heat exchange tube structure includes: the coating comprises a base material, a nickel-phosphorus coating and a sealing layer. Based on the two heat exchange tube samples and the heat exchange tube without antiseptic treatment, tests were carried out to compare the antiseptic property.

When a heat exchange tube sample corresponding to the second heat exchange tube structure is prepared according to the method provided by the embodiment, the process is as follows:

firstly, oil removal is carried out, and the oil removal agent comprises the following components: 15g/L of sodium carbonate, 15g/L of trisodium phosphate, 15g/L of sodium silicate and 2g/L of OP emulsifier, and degreasing is carried out at the temperature of 70 ℃ and the flow rate of 1m/s of degreasing agent for 5 min. And after the oil removal is finished, the oil removal agent is led out and deionized water is introduced at 1m/s for cleaning.

Then, acid washing is carried out, and the acid washing agent comprises the following components: 170mL/L of hydrochloric acid, 80mL/L of sulfuric acid, 3g/L of hexamethylenetetramine and 100g/L of sodium chloride, and carrying out acid pickling treatment at an acid pickling agent temperature lower than room temperature and an acid pickling agent flow rate of 0.5m/s for 2 min. After the oil removal, the pickling agent is led out and deionized water is introduced at 1m/s for cleaning.

And finally, carrying out treatment of an anti-corrosion coating and a sealing layer. In the process of carrying out the anticorrosive coating treatment, the first plating solution comprises the following components: 240g/L nickel chloride hexahydrate and 30% concentrationHydrochloric acid 320mL/L, set current 5A/dm²The electroless plating time was 3 seconds. After the electroplating treatment, the excessive pre-plating solution flows out, and deionized water is introduced at a rate of 1m/s for cleaning. The second plating solution comprises the following components: 50g/L of nickel sulfate, 25g/L of sodium dihydrogen phosphate, 40g/L of sodium citrate, 0.6g/L of copper sulfate, 35g/L of sodium acetate and 3mg/L of potassium molybdate, wherein the temperature of the second plating solution is 90 ℃, the flow rate of a circulating pump is 5mm/s, and the chemical plating time is 60 min. And after the chemical plating treatment is finished, deionized water is introduced at 1m/s for cleaning and air drying. In the sealing layer treatment process, the sealing liquid comprises the following components: 5g/L of polyurethane resin, 3g/L of surfactant and 1g/L of silane coupling agent, wherein the surfactant is surfactant OP-5. And after the sealing treatment is finished, the redundant sealing liquid is led out and naturally dried for 24 hours.

In the test process, the water quality of a typical area with the service life of the copper heat exchange tube within 1 year is selected as a corrosion test medium, and the corrosion resistance of the three samples is compared through an electrochemical test. As shown in fig. 4a, which shows the result of the open circuit potential test at 20 c, and as shown in fig. 4b, which shows the result of the open circuit potential test at 80 c, it can be determined from fig. 4a and 4b that the nickel-phosphorus plating layer has a sacrificial anode effect on the copper heat exchange tube.

Fig. 5a shows the results of the test and fitting of the polarization curves of the first heat exchange tube structure and the second heat exchange tube structure at 20 ℃, fig. 5b shows the results of the test and fitting of the polarization curves of the first heat exchange tube structure and the second heat exchange tube structure at 80 ℃, and the corrosion current can be determined from fig. 5a and 5b, so that the service life of the coating can be calculated according to the corrosion current. The following table 1 shows the fitting results shown in fig. 5a and 5b, and the data calculated according to the service time of 2h each day, the thickness of the anti-corrosion coating of the first heat exchange tube structure is 10 μm, and the thickness of the nickel-phosphorus coating of the second heat exchange tube structure is 10 μm. It can be seen that the heat exchange tube structure subjected to the anti-corrosion treatment according to the embodiment of the disclosure can ensure that the anti-corrosion service life is 8 years or more, so that the long-acting anti-corrosion of the heat exchange tube is realized, the service life of the heat exchange tube can be effectively prolonged, and the service life of the heat exchange tube is not less than the scrapped age of the heat exchanger.

TABLE 1

Samples corresponding to the nickel-phosphorus coating layer + sealing layer 1 and the nickel-phosphorus coating layer + sealing layer 2 are samples subjected to anticorrosion treatment according to the method for the anticorrosion treatment of the heat exchange tube; the nickel-phosphorus coating 1 and the nickel-phosphorus coating 2 are samples subjected to corrosion prevention treatment by using an electroplating method disclosed in the prior art, or samples subjected to corrosion prevention treatment in an electroplating treatment process in a method for performing corrosion prevention treatment on a heat exchange tube according to the present disclosure.

The above description and drawings sufficiently illustrate embodiments of the disclosure to enable those skilled in the art to practice them. Other embodiments may include structural and other changes. The examples merely typify possible variations. Individual components and functions are optional unless explicitly required, and the sequence of operations may vary. Portions and features of some embodiments may be included in or substituted for those of others. The embodiments of the present disclosure are not limited to the structures that have been described above and shown in the drawings, and various modifications and changes may be made without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims.

Claims

1. A method for the corrosion protection treatment of a heat exchange tube, comprising:

2. The method of claim 1, wherein the electroplating process comprises:

determining the electroplating time and the set current;

and electroplating the heat exchange tube by taking the heat exchange tube as a cathode and a nickel wire as an anode according to the set current and the electroplating duration.

3. The method of claim 1, wherein the electroless plating process comprises:

determining the chemical plating time length and the flow rate of a circulating pump;

and controlling the circulating pump to work according to the chemical plating time and the circulating pump flow rate.

4. The method of claim 1, wherein the electroless plating process comprises:

determining the chemical plating time length, the flow rate of a circulating pump and the swing period;

and controlling the circulating pump to work according to the chemical plating time and the flow rate of the circulating pump, and adjusting the position of the heat exchange tube according to the swing period.

5. The method of claim 4, wherein adjusting the position of the heat exchange tube according to a period of oscillation comprises:

determining two or more setting angles;

and controlling the heat exchange tube to maintain different setting angles in adjacent swing periods.

6. The method of claim 1, wherein the first plating solution is an acidic nickel salt solution;

the second plating solution comprises: nickel salts, dihydrogen phosphate, citrate, molybdate and acetate.

7. The method of claim 1, wherein the confining liquid comprises: water-based resin, silane coupling agent and surfactant.

8. A heat exchanger comprising a heat exchange tube, wherein the inner wall surface of the heat exchange tube comprises an anticorrosive coating and a sealing layer formed by the method according to any one of claims 1 to 7.

9. The heat exchanger of claim 8, wherein the corrosion protection coating has a thickness greater than a thickness of the seal layer.

10. A water heater comprising a heat exchanger as claimed in claim 8 or 9.