JP6151938B2 - Thermal radiation material - Google Patents

Description

The present invention relates to a heat radiation material that is applied to the inner wall surface of a high-temperature furnace to increase the temperature of the furnace and increase the radiant heat transfer in the furnace.

  Thermal radiation materials are mainly used by applying to the inner wall of the furnace in order to improve radiant heat transfer in various high-temperature facilities such as chemical reactors and heating furnaces. It is applied to the outer surface of the tube and used to raise the temperature of the medium in the tube by absorbing radiant heat.

Conventionally, as a heat radiation material, a material based on silicon carbide (SiC), chromite (Cr ₂ O ₂ ) and titanium oxide (TiO ₂₎ is known. Examples of the heat radiation material based on silicon carbide include H.P. R. CIII (trade name of Japan Thermal Radiation Materials Laboratory Co., Ltd.) is sold, but the furnace temperature is about 800 ° C. Examples of the heat radiation material based on chromite include H.P. R. C (also a trade name of the above-mentioned laboratory) is sold, but it can be applied to a furnace temperature of 1,000 ° C. or higher.

Furthermore, examples of the heat radiation material based on titanium oxide (TiO ₂ ) include H.P. R. CII (also the trade name of the above laboratory) is sold, but the titanium oxide (TiO ₂₎ of the base material is reduced titanium oxide when heated at a high temperature in a furnace of H ₂ or CO ₂ atmosphere. _{(Ti 2 O 3, Ti 3} O 5, ··· Ti n O 2n-1) changes to, well absorbs near infrared, a high radiation, the coating film of reduced titanium oxide on the inner wall surface of the furnace When baked and formed, the radiant heat transfer in the furnace increases dramatically, and its application area becomes 1,000 ° C. or more.

It is important to select by making use of the characteristics of each of these heat radiating materials. However, any heat radiating material has a problem that when it is applied to the iron plate, the affinity with the iron plate surface is poor and peeling occurs. is there.
On the other hand, several infrared radiation coating materials that can be painted on the surface of an iron plate and have a high emissivity are known. For example, a coating material based on an organic material has been proposed (Patent Document 1), but the emissivity is 0.8 or more and the heat resistance is 500 ° C., which can endure a very high temperature. It is not a thing and can only be used as a heat radiation material. In terms of heat resistance, Okitsumo (trade name of Okitsumo Co., Ltd.) is known as a heat resistant paint, but the heat resistance is at most 650 ° C. and is only used for rust prevention and aesthetic purposes. Regarding the emissivity, a value of 0.9 is reported for a product made in Hungary, but the heat resistance is 350 ° C., and this also has a limited application range as a heat radiation material.

Japanese Patent Laid-Open No. 62-288152

The problem to be solved by the present invention is a heat radiation material that can be coated on the surface of an iron plate, has a high emissivity of 0.9 or more, can withstand high temperatures from 700 ° C. to 1,500 ° C., and has a low cost. It is to provide low enough.

  The present invention has been made in view of such problems, and is a heat that can be applied to the surface of an iron plate, characterized in that it is based on a composition in which ferromanganese oxide and silica are mixed and water is added as a diluent. Radiant material.

  In reaction furnaces, heating furnaces, and heat exchangers, it is desirable to keep the furnace temperature as high as possible by reducing the amount of energy input from a heat source such as a burner in order to efficiently perform the reaction and heating and increase the economy. ing.

  If the inner wall of the furnace is covered with a heat radiating material, the material with higher emissivity absorbs more heat, so the temperature of the furnace wall rises and the amount of radiant heat transfer from the inner wall increases. The temperature of an object or a material to be heated can be raised. At this time, since the heat radiation material itself is also exposed to high heat, heat resistance is also required.

  As a result of the furnace temperature becoming higher, the temperature of the object to be heated can be increased in a shorter time, so that the amount of energy input and time are shortened, and the total energy consumption is reduced. Further, at this time, the temperature of the exhaust gas is remarkably lowered, and energy that is wasted is reduced, so that high efficiency and energy saving can be realized.

  In addition to use in a furnace, for example, it may be applied to the outer surface of a condenser used for solar thermal power generation. In this example, sunlight is collected and irradiated onto the iron pipe, the temperature of the medium in the pipe is raised, water vapor is generated by the heat of this medium, and the power generation turbine is rotated to generate power. Therefore, it is desired to absorb sunlight as an energy source with a high absorption rate.

When a substance is irradiated with light, part of it is reflected and part of it is absorbed. Therefore,
Reflectance + Absorptance = 1 Equation 1
Is established. On the other hand, the absorbed light is converted into heat energy to warm the substance, but the material radiates electromagnetic waves proportional to the fourth power of the absolute temperature T. In steady state, absorbed energy and radiant energy are equal,
Absorption rate = Emissivity Equation 2
Therefore, from Equation 1 and Equation 2,
Reflectivity + emissivity = 1 Equation 3
Is established.

In short, a substance with a high emissivity means that the absorption rate of light is high.
Therefore, if a heat radiation material with a high emissivity is applied to the outer surface of the condenser tube, sunlight is absorbed with a high absorption rate, and as a result, the heat radiation material applied to the surface of the condenser tube is heated to a correspondingly high temperature. As a result, the heat radiation from the heat radiating material where the iron pipe becomes hot is heated to a high temperature by heat conduction, and as a result, the medium flowing in the iron pipe also receives heat from the iron pipe at a high temperature due to heat conduction and becomes a high temperature. Become. Since the power generation efficiency can be increased as the medium flowing in the pipe can be heated to a higher temperature, the heat radiation material applied to the surface of the iron pipe is naturally required to have heat resistance at the same time.

If the heat radiation material that can be painted on the surface of the iron plate of the present invention is used on the inner wall of these furnaces, the outer surface of the condenser tube, etc., energy that is wasted can be easily obtained at a lower cost and at a higher temperature. It can be reduced and the economy can be improved.
The material of the heat radiation material of the present invention is an oxide of iron, manganese, and silicon, all of which are easily available, have a large amount as a resource, and are low in cost.

A heat radiation material that has a high emissivity, can withstand high temperatures of 700 to 1,500 ° C., and can be painted on the surface of an iron plate can be provided at low cost.

Emissivity graph

  The heat radiation material of the present invention is a paint containing iron manganese oxide, silica, and an inorganic binder as main components and water as a diluent.

First, an iron / manganese oxide powder and silica powder are used as main raw materials, and a small amount of silicon carbide, iron oxide, aluminum oxide, etc. are mixed to prepare an intermediate mixture. The components of the intermediate mixture were subjected to fluorescent X-ray analysis by a briquette method using a fluorescent X-ray analyzer (manufactured by Rigaku Corporation, ZSX100e). Specifically, the black pigment and the intermediate mixture were molded into a disk-like sample using a press machine, the disk-like sample was set in a holder of a fluorescent X-ray analyzer, and the fluorescent X-ray intensity was measured. Quantitative value obtained by FP quantification method, Ig of black pigment measured in advance
Correction was made using the loss value, and the content of each element was determined.

As a result, the intermediate mixture was ferromanganese oxide (FeMn) ₂ O ₃ 24.8 to 25.3%, silicon carbide SiC 7.9 to 8.4%, iron oxide Fe ₂ O ₃ 9.5 to 10 0.1%, aluminum oxide Al ₂ O ₃ 2.3-2.5%, calcium oxide CaO 1.7-1.9%, potassium oxide K ₂ O 0.7-0.9%, manganese oxide MnO ₂ 0 It was 0.3 to 0.5% and silica SiO _{2 was} 16.3 to 16.8%.

  In addition to the above main component of the intermediate mixture, an inorganic adhesive is added as a subcomponent in the same manner as a normal heat resistant coating material.

  Further, water is used as a diluent, and the remaining amount is diluted with water to a solid content of 65% by weight.

  Furthermore, in addition to the main component and subcomponents described above, additives usually used in coating materials such as plasticizers and thickeners may be added as necessary.

  The heat radiation material according to the above description was coated on a stainless steel plate as an iron plate to form a coating film having a thickness of 30 to 40 μm. After the coating film was dried, baking was performed at 710 ° C. or more to prepare a test material. When this test material was subjected to a heat resistance test, a continuous heating test and an intermittent operation test (repetition test at a temperature rise of 1,350 ° C. to a lower temperature of 700 ° C.) were performed 15 times. There was no.

Moreover, the result of having measured the radiation rate of this test material in the Kanagawa Industrial Technology Center is shown in FIG. As shown in FIG. 1, a high emissivity of 0.89 was obtained on average at a wavelength of 710 degrees Celsius and a wavelength of 1.50 to 14.00 μm. This center can only measure 710 ° C, and our radiometer (Quantum Logic Corporation Model 1310) shows a value of 0.92 at 1,250 ° C.

  In various plants, there are devices such as a reactor operating at a high temperature in order to increase efficiency or yield. In solar thermal power generation devices, a highly efficient method using high-temperature molten salt has been developed. By using the heat radiating material that can be painted on the iron plate of the present invention in the above apparatus, it is possible to operate at a higher temperature with the same energy and to improve the efficiency.

Claims (2)

The main raw materials are iron manganese oxide powder and silica powder, and at least silicon carbide 7 . An iron plate characterized by comprising a base material composed of 9 to 8.4% , iron oxide 9.5 to 10.1% , aluminum oxide 2.3 to 2.5%, and water added as a solvent. Thermal radiation material that can be painted on the surface. The heat radiation material according to claim 1,
A heat radiation material characterized in that the weight ratio of iron manganese oxide to silica is approximately 3 to 2.