DD287248A5 - THERMAL RADIATION ACTIVE COVERING METHOD AND METHOD FOR THE PRODUCTION THEREOF - Google Patents

Abstract

heat radiation active coating composition; coating; vitroceramic matrix; Temperature treatment; refractory lining; furnaces; furnaces; Heat exchanger; absorption-active solid content; Silicate glass; refractory fillers; Mineralizers; colloidal solution; Sol

Description

Field of application of the invention

The invention relates to a heat-radiation-active coating composition for coatings and to a method for the production thereof for the inner surfaces of the lining of industrial furnaces, furnace fireboxes, metallurgical vessels, heat exchangers and other heat transfer systems and burner stones. Radiation elements and other elements located in the interior of such systems. The heat-active coating units are available in all sectors of industry, agriculture, construction and services.

Characteristic of the known state of the art Heat application systems, such as industrial furnaces, furnaces, metallurgical vessels and certain types of Heat exchangers have a refractory lining made of masonry masonry, monolithic or block infeed

or multi-layer construction.

In the recently applied lightweight catfish fiber material comes in the form of mats, plates, strips and modules in

different strengths for use. Also known is the wallpapering of inner surfaces of the existing

Heavyweight lining with these fiber elements for the purpose of additional heat insulation and thus Enorgleelnspar. mg, in particular in batch furnace operation and in furnaces with frequently changing Oven temperature regime is very effective, since in addition to the loss of wall loss even lower storage heat and Persistence heat loss (lower inertia loss due to faster control behavior) and less wear of the Refractory lining occurs and performance increases of the aggregates are possible. The radiation emissivity of most refractories used in these refractory liners In the high-temperature range, building materials have an emissivity of less than or equal to 0.7. The emissivity

aluminosilicate fiber products is less than 0.4 (in some cases less than 0.3).

In the solution according to DE-AS 1302596, coatings which form a glass phase are produced from a mixture of substances,

consisting of calcium fluoride, silicon and calcium oxide, sodium carbonate, sodium fluoride, sodium silicate and silicon carbide and / or molybdenum carbide and / or graphite.

According to SU-UHS 881506 a frit of Fe ₂ O ₃ and a high proportion of flux is applied (the layer has a Emissivity close to 0.9). Both solutions have the disadvantage that they are applied relatively thick (greater than 2mm), which requires large amounts

are and an order on fibers is not possible. Another decisive disadvantage is the glass character

(Flux more than 50%) of these coatings. They have a narrow melting interval and overheating (even localized) can cause the layer to run off.

Furthermore, a wall lining for heaters to further improve the economic use of energy is known

(DE-PS 3016377), where between a binder-containing SiC coating and the inside of the heating furnace wall, a layer of an inorganic fibrous heat-insulating material is arranged. This SiC coating has the disadvantage that the

SiC is oxidized with oxygen in oxideric atmosphere and high temperatures and is not stable. After the solution of DD-WP 206522 refractory coating compositions of metallurgical slag certain Composition or chromium or SiC Materlal and fillers and binders used in a layer thickness of

2 to 5mm are applied, whereby thermal stresses occur and there is a risk of chipping, large quantities are needed, and can not be applied to fiber material.

It is also known that binder-containing metal oxide coatings on a scale basis without (DD-WP 223803) and with refractory Aggregates of alumina and / or magnesite (DD-WP 224099) are used. This achieves emissivities of 0.93. While this layer on solid refractory liners gives good results

Depending on the type, structure and manufacture of the fibers, fiber material may be used

Oven conditions at temperatures above 1100 ° C to flaking.

In general, it should be noted that the known coating compositions with a high emissivity for refractory linings, especially on oxidic basis, tend to flaking due to high brittleness. Particularly serious damage is observed in modern lightweight deliveries of refractory fibers.

The glassy matrix of known coatings changes in the course of use, so that the radiation activity decreases and so the operating parameters of the heat system are changed in an undesirable manner, at the same time the energy consumption

increases. Not infrequently even a dripping of the coating with known glassy matrix from the furnace wall or the absorption by the porous background material is observed.

The radiation-active oxides of the known coating compositions are effective in their Glasphasenübsrgänge

impaired. Is to eliminate this disadvantage, the glass phase content of known coatings minimized, this is associated with the disadvantage of Abplatzneigung described because the elasticity is lost and because an adjustment of the thermal expansion of the coating to the substrate material is no longer possible.

Object of the invention

The aim of the invention is a heat-radiation-active coating composition and the process for their preparation for wear-resistant coatings for intensifying the radiant heat transfer, to reduce the wall, storage, Beharrungswärme · and exhaust gas losses and wear of the refractory lining, especially in fiber delivery or Fasertapezierung, creating a permanent improvement in efficiency is achieved by reducing energy consumption and longer availability of equipment and performance improvement.

Explanation of the essence of the invention

The invention has for its object to produce a heat radiation active coating composition for coatings for the refractory lining of heat application systems with a Strahlungsemissionsgred to near 1.0 from the beginning of the operation of the plant at an application temperature to about 1800 K, which after application to the corresponding surfaces in a thickness of equal to or less than 1.0 mm, preferably less than 0.5 mm, even with intermittent thermal stress, in particular on fiber products, by appropriate viscosity, surface activity of the constituents, spinel formation and adaptation of the thermal physical properties, in particular the expansion of the carrier building material, a high elasticity and adhesiveness in a wide temperature range, high protection against abrasion and by sealing the microporous refractory surface has a high wear resistance at the application temperature.

When applied to fiber products, the post-shrinkage on the firing side is simultaneously reduced. According to the invention, the object is achieved by the coating having an vitroceramic matrix and the absorptive-active vitroceramic base mixture consisting of a dry and a liquid component, the dry component of the coating mixture being composed of:

a) 8 to 95 Ma .-% absorption-active solid content consisting of:

- 5 to 100Ma .-% of finely divided iron oxide and / or iron oxide mixtures, preferably in Minteralbestand the scale of iron and / or iron alloys and / or ferro-slag (solidified liquid scale) and / or iron ore and / or iron ore concentrate and / or black metallurgical Ofenflugstaub

- 0 to 60% by weight of finely divided chromium oxide-containing compounds (calculated as Cr ₂ O ₃ ), preferably chromite and / or chromite periclase and / or chromium oxide-containing secondary raw materials

0 to 30% by weight of finely powdered, easily oxidizable alloys such as FeCr and / or FeMn and / or FeSi and / or SiMn or

From 0 to 60 Ma.% Of finely divided carbon compounds, such as carbides (eg silicon carbide) and / or graphite and / or carbon black and / or high carbon contents,

b) 0.5 to 25% by weight of glass, preferably finely comminuted silicate glass breakage and / or glaze frits and / or substances based on natural and / or synthetic alkali and / or alkaline earth compounds and / or boron compounds,

c) 0 to 87% by weight refractory fillers consisting of finely comminuted porcelain and / or cordierite ceramic fracture and / or Al ₂ O ₃ "and / or aluminosilicate and / or MgO compounds and / or forsterite in the form of particles and / or finely porous granules and / or inorganic fiber chips, these refractory components consisting partly or wholly of the material of the refractory lining to which the coating is applied, preferably of secondary material,

d) 0.1 to 15 Ma ·% finely ground mineralizers such as ZrO ₂ , ZrSiO ₄ , TiO ₂ , ZnO, fluorides, sulfides, phosphates alone or mixed to stimulate Vitrokerammatrixbildung

in a grain size of at least 90Ma .-% less than or equal to 0.3mm.

The liquid component includes water and / or colloidal sols (Sol), preferably a silica sol-sodium polyphosphide mixture and / or dispersing and / or suspending and / or binding agents, preferably a silica-based lubricating binder.

Dry and liquid components are mixed before application cuf a suitable according to the application technology consistency and applied in a layer thickness of equal to or less than 1 mm, preferably less than 0.5 mm, in single or multiple application to the cold or still warm surface to be coated.

The two-component Vitrokeram mixture according to the invention can be cost-effectively brought to mortar consistency and serve as a joint layer between refractory components, such as blocks or blocks, preferably on forsterite or chromite or chromite / periclase or Magnesiaferrit base.

This mixture with mortar consistency can be up to 20Ma .-% short ceramic fibers and / or finely granular granules mixed

become.

The erfiridungsgemäße coating composition is after application to the refractory lining or as a joint layer between

subjected to refractory elements of a defined heat treatment for the formation of the Vitrokerammatrix.

According to the invention, the heat treatment to form the Vitrokerammatrix in the temperature range of 800 to

1700 ° C with holding times of at least 1 hour.

The inventive coatings with vitroceramic matrix are surprisingly spalling, even after intermittent

thermal operation and are characterized by a high elasticity in all temperature ranges of the application.

Apparently, this is caused by the large number of defects at the Krisiallgrenzen the Vitrokerammatrix. : drip off as at

known radiation-active materials with glass matrix does not occur. The high radiation activity of the invention

Masses is characterized by high consistency over the entire period of application. Decisive for the stated advantages over known radiation-active masses is the invention

formed vitroceramic matrix in the coating. The emission of embedded in the coating known radiation active

Oxide is surprisingly not hindered, but still activated. The once formed vitroceramic matrix records

beyond the stated range of application of the coating, even at temperatures above the formation temperature of the coating

Vitrokerammatrix, characterized by high stability. The adaptation of the thermal expansion of the strahlungsaktivnn coating to the substrate in a known manner on the Raw mixture components of the coating composition according to the invention. embodiments

The heat radiation active coating composition according to the invention for coatings with vitroceramic matrix of refractory linings and the process for their production will be explained in more detail below with reference to four exemplary embodiments.

example 1 The dry component of the coating mixture having the composition:

Mass in% mixing ratio ZrSiO ₄ Grain size in mm 30 mill scale Frit *) less than 0.3 17 mill scale Klei Nero, 1 6 FeSi 90 less than 0.1 1.5 Zeolithbasaltmehl kleiner0,03 36 Chamomile flour Ix less than 0.1 Vitrokoramic skeleton: 1.5 less than 0.03 8th less than 0.05

* Seger formula of glaze 0.42 Na ₃ O 0.03 K, 0

0.18 CaO 0.47Al ₂ O] 3.44 SiO ₁ 0.68 B] O ₁

0.27 ZnO 0.08 MgO 0.02 BaO

is mixed until reaching the color consistency with water and 5Ma .-% (based on dry component) silica sol G1 and the flame boundary surfaces and the remaining directed to the furnace chamber surface of a large radiation elements made of fireproof F15 single application in a thickness of about 0.4mm sprayed. After heating and heat treatment at 1150 ° C and 4 h hold time, the vitroceramic matrix of the coating is completely formed. The emission level of the coating is greater than 0.95 and remains stable over the entire oven travel. The coating resists oven temperatures of 135O ⁰ C ₁ is free from waste and does not tend to drip.

Example 2 For a Hubbiikenofen lining made of corundum concrete is a mixture (dry component) of:

Mass in% mixing ratio ZrSiO ₄ Grain size in mm 22 mill scale quartz flour less than 0.1 30 Chrome ore (about 50% Cr ₂ O ₃ ) less than 0.1 0 Mullitmehl klei nero, 1 5 Chamomile flour Ix less than 0.1 3 ball clay less than 0.05 vitroceramic skeleton: 2 less than 0.03 8th less than 0.04

mixed with water and stirred for color consistency. After addition of 2Ma .-% sulfide waste liquor, the mass is workable. The application is carried out by means of a spray gun in a thickness of about 0.4 mm. If necessary, depending on the degree of coverage and surface condition of the lining, it is sprayed a second time after drying.

After a temperature treatment of 1400 ⁰ C and 2 h holding time forms the vitroceramic matrix of the coating. The coating is resistant to over 155O ⁰ C and flake test against temperature changes. The emissivity of the furnace walls is 0.93.

Example 3

On the inner surfaces of the lining of a hearth furnace with intermittent operation, fibreboards with a thickness of 40mm are applied. Subsequently, the surface is coated with the coating mixture according to the invention. The dry component of the coating mixture is composed of:

Mass in% mixing ratio Glaze frit (corresponding to example 1) Grain size in mm 61 mill scale ZrSiO ₄ klei nero, 1 16 Cordieritbruchmehl less than 0.08 9 Chamomile flour Ix kleiner0,01 9 chromium oxide-stabilized fiber shreds (Fiber length less than 10mm) vitroceramic skeleton: 4.5 less than 0.05 0.5 less than 0.03

These ingredients are brought to color consistency with silica solbloit binder G1 before application. The order is made in single or multiple orders up to a thickness of 0.3mm. Subsequently, the coating is dried and a temperature of 1200 ⁰ C, 6h to form the Vitroceram matrix subjected. The coating makes the fiber lining erosion-resistant and radiation-active

(Emissivity equals 0.94). The lining is resistant to temperature changes and does not run off. The

Absorption is sustainably suppressed. Example 4 The dry component, consisting of: Mass In% Mixing ratio Grain in mm

5 mill scale klelnerO, 3

4 Glühzunder smaller 0.2

2 oven airborne dust fromE-melting furnaces smaller O.OS

2 quartz glass powder less than 0.05

1 ZrSiO ₄ less than 0.03

86 seawater magnesia less than 0.3

is brought to about 2 wt .-% sulfide liquor and water on Schlicker- or mortar consistency and can be used with or without the addition of fiber chips or finely porous granules as mortar for magnesite and / or chrome ore stones, for example for delivery in rotary kilns.

Claims (15)

claims: 1. A process for the preparation of a heat radiation active coating composition for coatings of refractory linings with a radiation emissivity close to 1.0 and high heat and abrasion resistance and elasticity in a wide temperature range even with intermittent thermal stress on the inner surfaces of industrial furnaces, furnaces, combustion chambers, metallurgical vessels, Heat exchangers and other heat transfer systems to increase the efficiency of heat transfer and wear protection using known application methods, characterized in that homogenized a vitroceramic base mixture with absorption active solids and optionally refractory fillers and a liquid component, applied to a refractory lining and a heat treatment of 800 ⁰ C to 1700 ⁰ C is subjected to a holding time of at least 1 hour, until the vitroceramic basic gomic a vitroceramic Ma trix is formed in the coating. 2. Radiation active coating composition using known absorption-active solid components and refractory fillers, characterized in that a basic vitroceramic mixture consisting of - 0.5 to 25Ma .-% silicate glass and 0.1 to 15% by weight of very finely ground mineralizers
With 3. thermal radiation active coating composition according to claim 2, characterized in that the absorption-active solid content of 4. thermal radiation active coating composition according to claim 2 and 3, characterized in that the iron oxide and / or iron oxide mixture in the mineral population of the scale of iron and / or iron alloys and / or ferro-slag and / or iron ore and / or iron ore concentrate and / or black metallurgical Ofenflugstaub lies. 5. thermal radiation active coating composition according to claim 2 and 3, characterized in that the chromium oxide-containing compounds are preferably chromite and / or chromite periclase and / or chromium oxide-containing secondary raw materials. - 5 to 100Ma .-% finely divided iron oxide and / or iron oxide mixtures and - 0 to eOMa .- ^ Of einteiligechromoxidhaltige compounds and 0 to 30 Ma .-% finely powdered, easily oxidizable metallic alloys or - 0 to 60Ma .-% finely divided carbon compounds. , 6. thermal radiation active coating composition according to claim 2 and 3, characterized in that the easily oxidizable metallic alloys FeCr and / or FeMn and / or FeSi and / or SiMn. 7. thermal radiation active coating composition according to claim 2 and 3, characterized in that are used as carbon compounds carbides and / or graphite and / or carbon black. 8. thermal radiation active coating composition according to claim 2, characterized in that preferably glass as finely comminuted silicate glass and / or glaze frits and / or substances based on natural and / or synthetic alkali metal uid / or alkaline earth metal compounds and / or boron compounds are used. - 8 to 95% by mass of absorption active solids and 0 to 87% by weight of refractory fillers is homogeneously mixed, wherein the Einscizstoffe have a grain size of at least 90Ma .-% equal to less than 0.3 mm and with a liquid binder component of 1 to 40 wt .-%, based on the dry ingredients, and if necessary, water, is made. 9. thermal radiation active coating composition according to claim 2, characterized in that the refractory fillers of finely divided porcelain and / or cordierite ceramic fracture and / or AI2O3 and / or aluminosilicate and / or MgO compounds and / or forsterite. 10. thermal radiation active coating composition according to claim 2 and 9, characterized in that the refractory fillers in the form of particles and / or finely porous granules and / or fiber particles is used. 11. thermal radiation active coating composition according to claim 2, 9 and 10, characterized in that the refractory fillers consists partially or completely of the material of the refractory lining, to which the coating is applied, preferably of secondary material. 12. thermal radiation active coating composition according to claim 2, characterized in that the mineralizers ZrÖ2, ZrSiOi, T1O2, ZnO, fluorides, sulfides, phosphates or mixtures thereof. 13. thermal radiation active coating composition according to claim 2, characterized in that the liquid component is water and / or a colloidal solution (sol), preferably a silica sol-sodium polyphosphate mixture and / or dispersion and / or suspension and / or binder, preferably a Glide binder based on silica sol. 14, heat radiation active coating composition according to claim 2 to 13, characterized in that the two-component Vitrokeram mixture according to the invention brought to mortar consistency and as a joint layer between refractory components, such as blocks or blocks, preferably on forsterite or chromite or chromite / periclase or periclas or Magnesiaferrit base is used. 15. thermal radiation active coating composition according to claim 14, characterized in that the two-component Vitrokeram mixture according to the invention with mortar consistency up to 20 Ma. ·% Short ceramic fibers and / or finely porous granules are mixed.