Wear-resistant and corrosion-resistant heat-pipe heat exchanger and preparation method therefor

Abstract

The present invention provides a wear-resistant and corrosion-resistant heat-pipe heat exchanger and a preparation method therefor. The preparation method in the present invention comprises: S1: soaking a heat pipe in an anti-corrosion solution containing β-cyclodextrin, gluconic acid, and a catalyst, and drying; S2, soaking the heat pipe in a sodium silicate solution, and drying; and S3, soaking the heat pipe in a solution containing PDMS and a matched curing agent, and curing to obtain the wear-resistant and corrosion-resistant heat-pipe heat exchanger. According to the present invention, the sodium silicate and the gluconic acid are used to respectively form films on the metal surface of the heat pipe, achieving dual-film synergistic anti-corrosion; and the cyclodextrin and the gluconic acid are combined, so that the thermal stability of the material is improved, adapting to a high flue gas temperature. In addition, the PDMS and the matched curing agent not only form a hydrophobic structure to isolate the impact of a corrosive medium, but also increase the viscosity of the dual-film, so that the film is not prone to falling off, and the sodium silicate has good strength, hardness and smoothness after being cured, capable of withstanding flue gas conditions with high dust content.

Description

Wear-resistant and corrosion-resistant heat pipe heat exchanger and preparation method thereof Technical Field

[0001] The present invention relates to the technical field of heat pipe heat exchangers, and in particular to a wear-resistant and corrosion-resistant heat pipe heat exchanger and a preparation method thereof. Background Art

[0002] In order to recover the heat loss caused by flue gas emission, a large number of low-temperature economizers are usually installed at the tail of the boiler. Low-temperature economizers are generally arranged between the air preheater and the electrostatic precipitator. The dust concentration of the flue gas at this location is relatively high, generally 20-50g / Nm 3 The dust-laden flue gas causes severe scouring and abrasion of the economizer's heat exchange tubes. Furthermore, the acidic gases in the flue gas corrode the tubes. Prolonged exposure to this scouring, abrasion, and corrosion can easily lead to tube perforations. These perforations can cause cooling water to leak into the flue gas, where it mixes with the flue gas dust and forms a solidified deposit at the bottom of the flue. This can lead to the loss of heat transfer capacity throughout the serpentine heat exchange tubes, necessitating the shutdown and isolation of the entire heat exchange module to prevent the cooling water from entering the flue, severely impacting the unit's operational reliability.

[0003] The current common solution to these problems is to use vacuum heat pipes with fins on the flue gas side. These vacuum heat pipe heat exchangers avoid the problem of water continuously entering the flue due to wear of the heat exchange tubes. However, due to the high dust concentration in the flue gas caused by the low-temperature economizer, the flue gas has a high dust concentration, which severely erodes the finned vacuum heat pipes. The external fins of the vacuum heat pipes are severely worn due to the long-term exposure to high-dust flue gas, which significantly reduces the heat exchange efficiency of the heat exchanger.

[0004] In view of this, the present invention is proposed.

[0005] Summary of the Invention

[0006] The purpose of the present invention is to provide a wear-resistant and corrosion-resistant heat pipe heat exchanger and a preparation method thereof, which are used to overcome the corrosion and wear problems of traditional low-temperature economizers and ensure the safe, stable and reliable operation of the heat pipe heat exchanger.

[0007] The present invention provides a method for preparing a wear-resistant and corrosion-resistant heat pipe heat exchanger, comprising the following steps in sequence:

[0008] S1: Immerse the heat pipe in an anti-corrosion solution containing β-cyclodextrin, gluconic acid and a catalyst and dry it;

[0009] S2: Immerse the heat pipe in sodium silicate solution and dry it;

[0010] S3: Immerse the heat pipe in a solution containing PDMS and its supporting curing agent, and after curing, obtain a wear-resistant and corrosion-resistant heat pipe heat exchanger.

[0011] Specifically, in step S1, the mass content of gluconic acid in the anti-corrosion solution is 20-30%, and the mass content of β-cyclodextrin is 10-20%; the catalyst is sodium dihydrogen phosphate, and the mass content of sodium dihydrogen phosphate in the anti-corrosion solution is 1-5%.

[0012] In particular, the preparation method of the anti-corrosion solution comprises: adding beta-cyclodextrin and a catalyst to a gluconic acid solution, stirring uniformly, and heating at 120-180° C. for 10-300 minutes.

[0013] In addition, in step S1, the soaking time is 10-15 hours; the drying temperature is 70-90° C., and the drying time is 4-6 hours.

[0014] In the above step S1, gluconic acid can complex with metal ions on the surface of the heat pipe metal to form an anti-corrosion film, thereby preventing the heat pipe metal from being continuously corroded; the intervention of β-cyclodextrin can increase the thermal stability of the anti-corrosion film formed by gluconic acid to adapt to higher flue gas temperatures.

[0015] In step S2, the mass content of the sodium silicate solution is 15-20%; in addition, the soaking time is 20-30 hours.

[0016] In the above step S2, sodium silicate can form a passivation film with the heat pipe metal, and synergistically act with the anti-corrosion film formed by gluconic acid to form a good anti-corrosion effect.

[0017] In step S3, the mass content of PDMS in the solution is 10-20%, the mass content of the curing agent is 1-2%, and the solvent of the solution is n-hexane; in addition, the immersion time is 8-12 minutes; and the curing time is 22-26 hours.

[0018] In the above step S3, PDMS can form a lotus leaf effect hydrophobic layer to prevent corrosive media such as moisture in the flue gas from contacting the heat pipe wall. While forming a hydrophobic structure to isolate the influence of the corrosive medium, PDMS and the matching curing agent can also increase the viscosity of the anti-corrosion film formed by gluconic acid and the passivation film formed by sodium silicate, making the double-layer film less likely to fall off; at the same time, sodium silicate has good strength, hardness and smoothness after curing, and can cope with dusty flue gas conditions; in particular, PDMS can form covalent bond bridges with the hydroxyl groups in the inner anti-corrosion film and the outer passivation film, thereby improving the thermal stability and viscosity of the anti-corrosion film and the passivation film.

[0019] The present invention also provides a wear-resistant and corrosion-resistant heat pipe heat exchanger, which is prepared according to the above preparation method.

[0020] The implementation of the present invention has at least the following advantages:

[0021] 1. The present invention forms an inner anti-corrosion film and an outer passivation film with the heat pipe metal by sodium silicate and gluconic acid respectively. The double films work synergistically to improve the anti-corrosion effect.

[0022] 2. The present invention combines β-cyclodextrin with gluconic acid through an esterification reaction, which increases the thermal stability of the material and can adapt to higher flue gas temperatures;

[0023] 3. The sodium silicate of the present invention has good strength, hardness and smoothness after curing, and can cope with flue gas and dust erosion;

[0024] 4. The present invention also uses PDMS and its supporting curing agent, which can not only form a hydrophobic structure to isolate the influence of corrosive media, but also increase the viscosity of the anti-corrosion film and the passivation film, making the anti-corrosion film and the passivation film not easy to fall off;

[0025] 5. The PDMS of the present invention can form a covalent bond bridge with the inner anti-corrosion film and the outer passivation film, overcoming the capillary action of water and thus improving the stability of the anti-corrosion film and the passivation film;

[0026] 6. The modification cost of the present invention is low, the loss is small, the maintenance cost is low, and the maintenance and flushing are convenient. During regular inspections, the heat pipe wall can be flushed with circulating water to make it look brand new. It is adaptable to various flue gas conditions and can well meet the actual application needs. DETAILED DESCRIPTION

[0027] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0028] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular also includes the plural. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0029] The technical solutions of the present invention are described clearly and completely below with reference to the embodiments. It is obvious that the embodiments described are only a portion of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are also within the scope of protection of the present invention.

[0030] Example 1

[0031] The preparation method of the wear-resistant and corrosion-resistant heat pipe heat exchanger of this embodiment comprises the following steps:

[0032] 1) A 20 wt % gluconic acid solution was prepared, and then 1 wt % sodium dihydrogen phosphate was added to the gluconic acid solution, and the mixture was stirred thoroughly to dissolve. Then, 10 wt % β-cyclodextrin was added, and the mixture was stirred uniformly. The mixture was heated at 120° C. for 4 h to prepare an anti-corrosion solution.

[0033] 2) Soak the heat pipe to be modified in the anti-corrosion solution of step 1) for 12 hours, take it out, and dry it at 80° C. for 5 hours.

[0034] 3) preparing a 15 wt % sodium silicate solution, placing the heat pipe modified in step 2) in the sodium silicate solution for 24 hours, then taking it out and blowing it dry.

[0035] 4) Add 10 wt% of PDMS to n-hexane and add 1 wt% of a matching curing agent, stir thoroughly to dissolve, and prepare a wear-resistant solution.

[0036] 5) placing the heat pipe modified in step 3) in a wear-resistant solution, soaking for 10 minutes, taking it out, and naturally curing it for 24 hours to obtain a wear-resistant and corrosion-resistant heat pipe heat exchanger.

[0037] Example 2

[0038] The preparation method of the wear-resistant and corrosion-resistant heat pipe heat exchanger of this embodiment comprises the following steps:

[0039] 1) A 25 wt % gluconic acid solution was prepared, and then 3 wt % sodium dihydrogen phosphate was added to the gluconic acid solution, and the mixture was stirred and dissolved. Then, 15 wt % of β-cyclodextrin was added, and the mixture was stirred and heated at 150° C. for 2 h to prepare an anti-corrosion solution.

[0040] 2) Soak the heat pipe to be modified in the anti-corrosion solution of step 1) for 10 hours, take it out, and dry it at 70° C. for 6 hours.

[0041] 3) preparing a 20 wt % sodium silicate solution, placing the heat pipe modified in step 2) in the sodium silicate solution for 20 hours, then taking it out and drying it with air.

[0042] 4) Add 15 wt % of PDMS to n-hexane and add 2 wt % of a matching curing agent, stir thoroughly to dissolve, and prepare a wear-resistant solution.

[0043] 5) placing the heat pipe modified in step 3) in a wear-resistant solution, soaking for 8 minutes, taking it out, and naturally curing it for 22 hours to obtain a wear-resistant and corrosion-resistant heat pipe heat exchanger.

[0044] Example 3

[0045] The preparation method of the wear-resistant and corrosion-resistant heat pipe heat exchanger of this embodiment comprises the following steps:

[0046] 1) A 30 wt % gluconic acid solution was prepared, and then 5 wt % sodium dihydrogen phosphate was added to the gluconic acid solution, and the mixture was stirred and dissolved. Then, 20 wt % of β-cyclodextrin was added, and the mixture was stirred and heated at 180° C. for 1 h to prepare an anti-corrosion solution.

[0047] 2) Soak the heat pipe to be modified in the anti-corrosion solution of step 1) for 15 hours, take it out, and dry it at 90° C. for 4 hours.

[0048] 3) preparing an 18 wt % sodium silicate solution, placing the heat pipe modified in step 2) in the sodium silicate solution for 30 hours, then taking it out and drying it with air.

[0049] 4) Add 20 wt% of PDMS to n-hexane and add 2 wt% of a matching curing agent, stir thoroughly to dissolve, and prepare a wear-resistant solution.

[0050] 5) placing the heat pipe modified in step 3) in a wear-resistant solution, soaking for 12 minutes, taking it out, and naturally curing it for 26 hours to obtain a wear-resistant and corrosion-resistant heat pipe heat exchanger.

[0051] Comparative Example 1

[0052] Except that gluconic acid is not added to the anti-corrosion solution in step 1), the rest is basically the same as in Example 1.

[0053] Comparative Example 2

[0054] Except that step 3) is not performed (ie, the sodium silicate solution treatment is not used), the rest is basically the same as in Example 1.

[0055] Comparative Example 3

[0056] Except that β-cyclodextrin is not added to the anti-corrosion solution in step 1), the rest is basically the same as in Example 1.

[0057] Comparative Example 4

[0058] Except that step 4) and step 5) (ie, PDMS and the supporting curing agent are not used for treatment), the rest is basically the same as Example 1.

[0059] Test Example 1

[0060] The coating strength, wear resistance and corrosion resistance of the heat pipe exchangers of each embodiment and the comparative example were tested using an adhesive strength tester, a falling sand method and a simulated acidic environment. The specific results are shown in Tables 1 and 2, respectively.

[0061] Table 1 Test results of heat pipe heat exchangers in various embodiments

[0062] Table 2 Test results of heat pipe heat exchangers of various comparative examples

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a wear-resistant and corrosion-resistant heat pipe heat exchanger, characterized in that: The steps include the following sequence: S1: Immerse the heat pipe in an anti-corrosion solution containing β-cyclodextrin, gluconic acid and a catalyst and dry it; S2: Immerse the heat pipe in sodium silicate solution and dry it; S3: Immersing the heat pipe in a solution containing PDMS and a curing agent, and curing to obtain a wear-resistant and corrosion-resistant heat pipe heat exchanger.

2. The preparation method according to claim 1, characterized in that The mass content of gluconic acid in the anti-corrosion solution is 20-30%, and the mass content of beta-cyclodextrin is 10-20%.

3. The preparation method according to claim 1, characterized in that The catalyst is sodium dihydrogen phosphate, and the mass content of the sodium dihydrogen phosphate in the anti-corrosion solution is 1-5%.

4. The preparation method according to claim 1, characterized in that The preparation method of the anti-corrosion solution comprises the following steps: adding beta-cyclodextrin and a catalyst into a gluconic acid solution, stirring the solution uniformly, and then heating the solution at 120-180° C. for 10-300 minutes.

5. The preparation method according to claim 1, characterized in that In step S1, the soaking time is 10-15 hours; the drying temperature is 70-90° C., and the drying time is 4-6 hours.

6. The preparation method according to claim 1, characterized in that The mass content of the sodium silicate solution is 15-20%.

7. The preparation method according to claim 1, characterized in that In step S2, the soaking time is 20-30 hours.

8. The preparation method according to claim 1, characterized in that The mass content of PDMS is 10-20%, and the mass content of its matching curing agent is 1-2%.

9. The preparation method according to claim 1, characterized in that In step S3, the soaking time is 8-12 minutes; and the curing time is 22-26 hours.

10. A wear-resistant and corrosion-resistant heat pipe heat exchanger, characterized in that: Prepared according to the preparation method according to any one of claims 1 to 9.

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