KR101639058B1 - Heat exchange tube coated with non-metal oxides - Google Patents

Heat exchange tube coated with non-metal oxides Download PDF

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Publication number
KR101639058B1
KR101639058B1 KR1020150182608A KR20150182608A KR101639058B1 KR 101639058 B1 KR101639058 B1 KR 101639058B1 KR 1020150182608 A KR1020150182608 A KR 1020150182608A KR 20150182608 A KR20150182608 A KR 20150182608A KR 101639058 B1 KR101639058 B1 KR 101639058B1
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South Korea
Prior art keywords
coating layer
heat exchange
exchange tube
oxide
heat
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KR1020150182608A
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Korean (ko)
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성상미
Original Assignee
주식회사 성진에스이
성상미
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F19/00—Preventing the formation of deposits or corrosion, e.g. by using filters or scrapers
    • F28F19/02—Preventing the formation of deposits or corrosion, e.g. by using filters or scrapers by using coatings, e.g. vitreous or enamel coatings
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D1/00—Coating compositions, e.g. paints, varnishes or lacquers, based on inorganic substances
    • C09D7/1216—
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
    • F22B37/00—Component parts or details of steam boilers
    • F22B37/02—Component parts or details of steam boilers applicable to more than one kind or type of steam boiler
    • F22B37/10—Water tubes; Accessories therefor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F1/00—Tubular elements; Assemblies of tubular elements
    • F28F1/10—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Materials Engineering (AREA)
  • Wood Science & Technology (AREA)
  • Organic Chemistry (AREA)
  • Geometry (AREA)
  • Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)

Abstract

The present invention relates to a heat-exchanging tube coated with non-metal oxides. More specifically, the present invention relates to the heat-exchanging tube coated with non-metal oxides, providing a coating layer made of non-metal oxides which improves corrosion resistance and abrasion resistance of the heat-exchanging tube generating steam by exchanging heat in a boiler facility installed in a power generation facility or an incinerator, has excellent thermal conductivity, and prevents a crack caused by thermal expansion. Moreover, the heat-exchanging tube coated with non-metal oxides can increase durability of the non-metal oxide coating layer.

Description

{HEAT EXCHANGE TUBE COATED WITH NON-METAL OXIDES} <br> <br> #

The present invention relates to a heat exchange tube for generating steam through heat exchange in various boiler facilities such as a circulating fluidized bed boiler (BFB), an arrangement recovery boiler (HRSG) and an incinerator of a cogeneration power plant, The present invention relates to a heat exchange tube coated with a non-glazing type non-metallic oxide capable of preventing cracks caused by heat generated in a heat exchange tube and a coating method thereof.

Generally, a boiler for generating high-temperature steam in a steam-generating power plant includes a combustion furnace 10, a waste heat recovery apparatus 30, a desulfurization plant 40, A dust collector 50, and a chimney 60.

The combustion furnace 10 is a device for generating a high temperature of about 1000 to 1300 ° C by burning a liquid fuel such as bunker seed oil or heavy oil or a solid fuel such as coal, wood chips, waste vinyl, building waste wood, In this process, the water supplied to the heat exchange tube 20 is converted into high-temperature and high-pressure steam through heat exchange and then transferred to a gas turbine (not shown) to rotate the blades of the turbine to produce electricity.

The waste heat recovery apparatus 30 is a device for recovering and recycling the residual heat in the combustion gas after the heat exchange in the heat exchange tube 20. The desulfurization facility 40 is a device for recovering the harmful gas such as sulfuric acid or chlorine gas contained in the combustion gas The dust collector 50 is a device for filtering ash and dust in the combustion gas. The chimney 60 discharges the process gas after the dehairing process and the dust collecting process to the atmosphere .

The heat exchange tube 20 is mainly made of carbon steel in consideration of the fact that it is installed in a high temperature environment of the combustion furnace 10. The heat exchange tube 20 is in continuous contact with sulfuric acid or chlorine gas contained in the combustion gas Corrosion occurs and abrasion occurs due to contact with foreign matter or ash, resulting in puncture of the fragile portion, resulting in leakage of water.

In order to solve such a problem, there is a method of using a stainless steel material as the material of the heat exchange tube 20 in order to improve abrasion resistance and corrosion resistance of a heat-bridged tube. However, since stainless steel is expensive compared to carbon steel, And it is also inefficient because it takes a long time and a lot of time to perform welding on the entire surface of the heat exchange tube 20, which is also ineffective.

As an example for improving the surface of the heat exchange tube, a Korean Registered Utility Model No. 20-0387131 (Patent Document 1) discloses a heat exchanging tube or a heat exchanging tube A method of dipping in an aluminum solution heated to an appropriate temperature to be plated, an aluminum electrolytic plating method, or a spraying method in order to prevent corrosion of the outer surface of the piping or the surface of the finned heat exchange pipe and the surface of the fin, A heat exchange pipe has been proposed in which the inner surface and the outer surface of the pipe and the surface of the fin are plated with aluminum. However, since this method is cured and solidified in the liquid phase, Since cracks tend to occur and the hardness of aluminum is low, the ash and dust contained in the combustion gas Therefore, this algorithm is the durability of the coating, such as wear occurs as good contact with the quality and continuously.

As another method for improving the surface of the heat exchange tube, there is a method of forming a glazing-type surface coating layer by applying a non-metal oxide coating agent having wear resistance and corrosion resistance. However, In order to remove foreign substances such as adherents while expanding the volume of the liquid stream by vapor, a glazing-type coated non-metallic oxide The coating layer also causes peeling. Further, since the metallic heat exchange tube has a large thermal expansion coefficient, the non-metallic oxide coating agent has a relatively low thermal expansion coefficient, so that the coating layer easily peels off due to the difference in the thermal expansion coefficient when it is placed under the high temperature environment in the combustion furnace.

1. Korean Registered Utility Model No. 20-0387131 (published on June 17, 2005)

SUMMARY OF THE INVENTION The present invention for solving the problems of the prior art described above is to provide a heat exchange tube for generating steam through heat exchange in a boiler facility installed in a power generation facility or an incinerator to improve the corrosion resistance and wear resistance of the heat exchange tube, Coated with a non-glazing nonmetal oxide that is vitrified during use to provide a coating layer with a non-metallic oxide containing silicon carbide and cobalt oxide that can prevent cracking and improve the durability of the non-metallic oxide coating layer The object of the present invention is to provide a heat exchange tube.

In order to accomplish the above object, the present invention is characterized in that a coating layer is formed on a surface of a heat exchange tube installed in a combustion furnace to convert circulating water into steam, and includes a non-glazing type non-metal oxide coating agent do.

As a preferred embodiment, the apparatus further comprises a plurality of anchors fixed to the surface of the heat exchange tube, wherein the non-metallic oxide coating agent may be coated on the surface of the anchor.

In a more preferred embodiment, the coating layer includes a first coating layer in contact with the heat exchange tube, and a second coating layer coated on the outer surface of the first coating layer, wherein the second coating layer is a non-expansive nonmetal oxide coating, The thermal expansion coefficient of the second coating layer is relatively larger than that of the second coating layer, and the thermal expansion coefficient of the second coating layer is smaller than the thermal expansion coefficient of the heat exchange tube.

According to the present invention, a non-metallic oxide having a high thermal conductivity and high hardness is used in a cost-effective manner, that is, under a high temperature environment in a combustion furnace after surface coating, and is melted and formed into a coating layer, thereby being excellent in wear resistance, durability and corrosion resistance.

In addition, if an anchor is attached to the surface of the heat exchange tube, the surface area of the heat exchange tube can be increased and the surface roughness can be lowered, thereby reducing the peeling phenomenon of the metal oxide coating layer.

Further, by forming a non-metal oxide coating layer on the surface of the heat exchange tube, and further forming an intermediate coating layer having a middle thermal expansion coefficient between the heat exchange tube and the non-metal oxide coating layer, the thermal expansion gap between the heat exchange tube and the non-metal oxide coating layer can be minimized, The coating layer peeling phenomenon can be prevented, and the durability can be greatly improved.

1 is a schematic view of a boiler of a general steam generating power plant.
FIG. 2 is an enlarged cross-sectional view of part 'A' of FIG. 1 showing a cross section of a heat exchange tube coated with a non-metallic oxide of the present invention.

Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to FIG. 2 of the accompanying drawings. It should be understood, however, that there is no intention in the art to limit the present invention, as it is intended to be illustrative only and not for purposes of limitation, A detailed description thereof will be omitted.

FIG. 2 is an enlarged cross-sectional view of part 'A' of FIG. 1 showing a cross section of a heat exchange tube coated with a non-metallic oxide of the present invention.

2, the heat exchange tube 20 of the present invention is installed in a combustion furnace 10 such as a circulating fluidized bed boiler (BFB), an arrangement recovery boiler (HRSG) and an incinerator of a cogeneration system, For example, a cylindrical tube having an outer diameter of about 30 to 70 mm and a thickness of about 5 mm by using carbon steel, and the present invention can be applied to heat exchange The diameter, thickness, and material of the tube 20 are not limited to those illustrated.

Such a heat exchange tube 20 should be excellent in corrosion resistance and abrasion resistance, have a high thermal conductivity for rapid heat exchange, and have little cracks or cracks due to thermal expansion. To this end, the coating layer 210 is formed on the surface of the heat exchange tube 20, which includes a non-metallic oxide coating agent having an excellent thermal conductivity while preventing corrosion due to thermal expansion while improving corrosion resistance and abrasion resistance. The thickness of the coating layer 210 may be 5 mm or less, preferably 0.1 to 2 mm.

In order to prevent the coating layer 210 from being easily peeled off by increasing the surface area of the heat exchange tube 20 and reducing the surface roughness to roughen the surface thereof, the surface of the heat exchange tube 20 is further provided with a plurality of anchors May be fixed.

The anchor 220 may be fixed to the surface of the heat exchange tube 20 by welding using carbon steel or stainless steel. The anchor 220 may have a predetermined thickness and shape or an unspecified shape. At this time, the coating layer 210 may be coated on the surface of the anchor 220.

The coating layer 210 may include a first coating layer 211 in contact with the heat exchange tube 20 and a second coating layer 212 coated on the outer surface of the first coating layer 211. In this case, The second coating layer 212 directly contacting with the high temperature heat in the combustion furnace is a nonmetal oxide coating material and the first coating layer 211 is formed of a material having a relatively larger thermal expansion coefficient than the second coating layer 212 desirable.

Furthermore, it is preferable that the thermal expansion coefficient of the first coating layer 211 is smaller than the thermal expansion coefficient of the heat exchange tube 20.

In this case, the first coating layer 211 formed between the metallic heat exchange tube 20 having a relatively large thermal expansion coefficient and the second coating layer 212, which is a nonmetal oxide having a relatively small thermal expansion coefficient, It is possible to reduce the difference in thermal expansion coefficient between the respective layers due to the intermediate thermal expansion coefficient of the coating layer 212. In this way, the peeling phenomenon due to the difference in thermal expansion coefficient can be prevented or reduced.

The non-metal oxide coating agent may be selected from silicon carbide, cobalt oxide, nickel oxide, alumina and silica having a hardness of 9 or more at the Mohs hardness, a small crack due to thermal expansion, and an excellent thermal conductivity, and water glass can be used as the binder The mixing ratio of these materials and the characteristics thereof are shown in Table 1 below.

<Composition> No 1 No 2 No 3 No 4 No 5 Silicon carbide 90 70 50 5 0 Magnesium oxide 0 One 10 3 0 Nickel oxide 0 One 10 2 0 Alumina 0 2 0 25 55 Silica 5 20 22 50 0 water glass 5 5 8 15 45 <Characteristics> Vitrified state ☆☆ ☆☆ ☆☆☆ ☆☆☆ ☆☆☆ Heat conduction state ☆☆☆☆ ☆☆☆☆ ☆☆☆ ☆☆ ☆ / insulation layer formation Adhesion of coating layer × (peeling) ☆☆ ☆☆☆ ☆☆☆ × (peeling) compatibility incongruity fitness fitness fitness incongruity

As shown in Table 1, the peeling phenomenon occurred in No 1 and No 5, in particular, in the case of No 5, the thermal conductivity was not formed. In the case of No 2 to No 4, vitrification, thermal conductivity, The peeling property was good.

When the amount of silicon carbide is less than 5% by weight, the effect of thermal conductivity is insufficient. When the amount of silicon carbide is more than 70% by weight, thermal conductivity and abrasion resistance are excellent, but peeling phenomenon occurs.

When the content of alumina is more than 25 wt%, the abrasion resistance is excellent, but the thermal conductivity is low, which interferes with the heat conductivity of the heat exchange tube, which is against the purpose of the heat exchanger.

Magnesium oxide and nickel oxide have a high thermal expansion coefficient and swell at the same time when the heat exchanger water pipe is in a pycnometer. When the contents of magnesium oxide and nickel oxide are less than 1 wt% each, the thermal expansion function is insufficient. And when it is more than 10% by weight, the wear resistance is insufficient and the role of the heat exchanger water pipe can not be expected.

In case of silica, it is a typical low expansion material. When it is contained in an amount of more than 50% by weight, peeling phenomenon occurs remarkably. If it is less than 20% by weight, it does not help vitrification function.

The water glass functions as a main binder. When the amount is less than 5% by weight, the bonding force is low and the adhesion is low. When the weight is more than 15% by weight, the coating agent is melted at high temperature by soda in the water glass.

As a result, the non-metal oxide coating agent may contain 5 to 70% by weight of silicon carbide, 2 to 25% by weight of alumina, 1 to 10% by weight of magnesium oxide, 1 to 10% by weight of nickel oxide %, Silica 20-50 wt%, and binder 5-15 wt%

The binder is not limited to the water glass exemplified above, and may be an inorganic or organic binder or a binder mixed with an organic material and an inorganic material. The material and the kind of the binder are not limited, but those having heat resistance are preferable.

The non-metallic oxide particles can be selected as particles smaller than 200 mesh. They are non-glazig coated in the form of particles on the surface of the heat exchange tube 20 in a state mixed with the binder, It is free from cracks and cracks due to thermal expansion, and is excellent in corrosion resistance and abrasion resistance.

On the other hand, the coating material of the first coating layer 211 is a material having a thermal expansion coefficient larger than the thermal expansion coefficient of the second coating layer 212, for example, a coating material containing boron as a main component such as cobalt oxide and nickel oxide, Specifically, 5 to 20% by weight of a mixture of one or more selected from the group consisting of chromium oxide, magnesium oxide, nickel oxide, manganese oxide and cobalt oxide, and 80 to 95% by weight of a coating material of boron or silica- However, in the present invention, as long as the material having the intermediate thermal expansion coefficient of the heat exchange tube 20 and the second coating layer 211 as described above is not limited, there is no limitation on the material, and the cobalt oxide, , The blending ratio of these is not limited either.

Although the present invention has been described in connection with the preferred embodiments described above, it will be appreciated by those skilled in the art that various other modifications and variations can be made without departing from the spirit and scope of the invention, All such changes and modifications are intended to be within the scope of the appended claims.

10: Combustion furnace
20: Heat exchange tube
30: Waste Heat Recovery Unit
40: Desulfurization equipment
50: Dust collector
60: chimney
210: Coating layer
211: first coating layer
212: Second coating layer
220: anchor

Claims (6)

A heat exchange tube installed in a combustion furnace and converting circulating water into steam,
A coating layer including a non-glazing type non-metallic oxide coating agent which is vitrified during use is formed on the surface of the heat exchange tube,
Wherein the coating layer comprises a first coating layer in contact with the heat exchange tube, and a second coating layer coated on an outer surface of the first coating layer, wherein the second coating layer is a non-
Wherein the first coating layer has a relatively higher thermal expansion coefficient than the second coating layer.
The method according to claim 1,
Further comprising a plurality of anchors fixed to a surface of the heat exchange tube,
Wherein the coating layer is coated on the surface of the anchor.
delete The method according to claim 1,
Wherein the first coating layer has a thermal expansion coefficient less than that of the heat exchange tube.
The method according to claim 1,
Wherein the coating agent for the non-metallic oxide includes 5 to 70 wt% of silicon carbide, 2 to 25 wt% of alumina, 1 to 10 wt% of magnesium oxide, 1 to 10 wt% of nickel oxide, 1 to 50 wt% of silica, &Lt; / RTI &gt; coated with a non-metallic oxide.
The method according to claim 1,
Wherein the coating agent of the first coating layer comprises 5 to 20% by weight of at least one selected from the group consisting of chromium oxide, magnesium oxide, nickel oxide, manganese oxide and cobalt oxide and 80 to 95% by weight of a boron or silica- Wherein the heat exchanger tube is coated with a non-metallic oxide.
KR1020150182608A 2015-12-21 2015-12-21 Heat exchange tube coated with non-metal oxides KR101639058B1 (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117906402A (en) * 2024-03-19 2024-04-19 三明市丰润化工有限公司 Energy-saving recovery device of sodium silicate kiln
CN117906402B (en) * 2024-03-19 2024-05-31 三明市丰润化工有限公司 Energy-saving recovery device of sodium silicate kiln

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005156057A (en) * 2003-11-27 2005-06-16 Osaka Gas Co Ltd Sulfuric acid dew point corrosion preventive heat exchanger and its application method
KR200387131Y1 (en) 2004-11-16 2005-06-17 박향수 Heat exchanging tube with fins coated with aluminium
KR20150010983A (en) * 2012-05-16 2015-01-29 밥콕 앤 윌콕스 뵐운트 아/에스 Heat exchanger having enhanced corrosion resistance

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005156057A (en) * 2003-11-27 2005-06-16 Osaka Gas Co Ltd Sulfuric acid dew point corrosion preventive heat exchanger and its application method
KR200387131Y1 (en) 2004-11-16 2005-06-17 박향수 Heat exchanging tube with fins coated with aluminium
KR20150010983A (en) * 2012-05-16 2015-01-29 밥콕 앤 윌콕스 뵐운트 아/에스 Heat exchanger having enhanced corrosion resistance

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117906402A (en) * 2024-03-19 2024-04-19 三明市丰润化工有限公司 Energy-saving recovery device of sodium silicate kiln
CN117906402B (en) * 2024-03-19 2024-05-31 三明市丰润化工有限公司 Energy-saving recovery device of sodium silicate kiln

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