JPH054874A - Fire resisting mortar composition - Google Patents

Abstract

PURPOSE: To provide a fire-resistant mortel composition exhibiting a high thermal conductivity including fire-resistant materials, conductive metal, and connecting materials.

CONSTITUTION: The dried mixture of fire-resistant materials such as silicon carbide and aluminum nitride, thermal conductive metal such as copper, silver, and nickel, and the alloy and the mixture, and connecting agent such as phosphate system is dry mixed until they can be made uniform. Liquid components are added to this mixture as necessary, and then water is added so that a mortal composition can be prepared. This mortal composition has high thermal conductivity, and when this is packed between the hot air tube of a boiler and a tubular block or shield using SiC for protecting it as basic materials so that the heat efficiency of the boiler can be improved.

COPYRIGHT: (C)1993,JPO

Description

Detailed Description of the Invention

[0001] Technical Field The present invention contains the thermally conductive metal, relates mortar composition to a refractory based material. This composition exhibits high thermal conductivity.

[0002] refractory structures such as block and shielding BACKGROUND tube invention are often used to protect the hot air ducts, hot water pipe, a variety of structures, including the steam tube from heat loss. Boiler hot air tubes, steam tubes and water tubes are also protected by blocks or shields of such tubes to prevent corrosion caused by by-products of the materials combusted in the boiler. Shields and tube blocks are particularly useful in high temperature boilers such as those found in incinerators and commercial power plant boilers.

The tube blocks and shields used to protect such boiler tubes are generally not exposed to temperatures above about 700 ° C. in actual use, yet
It is generally made of silicon carbide because silicon carbide materials can withstand extremely high temperatures (up to 1000 ° C). Furthermore, SiC-based refractory tube blocks and shields have a relatively high thermal conductivity which results in good heat transfer in the boiler tube. This is important because some boiler tubes typically contain superheated steam, which is used, for example, to pass steam through a steam turbine to generate electricity. Thus, good heat transfer is required to operate a highly efficient boiler.

Although such tube blocks and shields have relatively high thermal conductivity, good heat flow between tube blocks or shields is desired due to manufacturing variations in the walls of the assembled metal tubes. It is often not available because it does not allow to make a fire resistant tube block or shield with the tight tolerances required for the best possible installation. As such, voids can result that result in insufficient heat flow between the block or shield and the metal tube. This inadequate heat flow has often been found to reduce the performance of tube blocks and heat shields.

One solution to this problem is to fill the voids with a refractory-based mortar.
However, prior art mortars based on SiC have a relatively low thermal conductivity which results in a heat flow far from optimal.

For example, US Pat. No. 4,682,568 is:
Disclosed is a superheater tube shield composed of nitride bonded silicon carbide. A refractory mortar is placed between the tube shield and the tube. This mortar helps keep the shield in contact with the boiler tube. The mortar comprises green silicon carbide, calcium aluminate and water. U.S. Pat. No. 4,767,790 discloses a tube shield attached to a boiler tube with the aid of the same refractory mortar.

US Pat. No. 4,562,958 is 5-10%
Of water and about 90-95% mixture containing 75-85% silicon carbide and 15-25% binder, wherein the binder is sodium aluminate, silica. Sodium acid and sodium phosphate may be used.

US Pat. No. 3470004 discloses a refractory mortar comprising 78-92% fused cast refractory particles containing chromium ore and magnesia, a water soluble sodium silicate plasticizer and an organic wetting agent. .

Each of these prior art refractory-based mortar compositions is in that each does not contain any conductive metal particles or other components that substantially enhance the heat flow properties of the mortar. Different from the composition of the present invention.

SUMMARY OF THE INVENTION The present invention addresses the problem of poor thermal conductivity known to be associated with prior art mortars by incorporating a conductive metallic material throughout the mortar composition. Solve. As used herein, the term "conductive" means thermally conductive.

The mortar composition comprises a refractory material such as silicon carbide, a conductive metal such as copper, and a binder. The presence of a conductive metal causes the thermal conductivity of mortar to be about 60 to 2,000 BTU · in / hr · ft ² · ° F.
(740 to 24,800 kcal · cm / hr · m ² · ° C).
The thermal conductivity of similar refractory compositions that do not contain conductive metals is generally about 33 BTU · in / hr · ft ² · ° F (410 kcal · cm
/ Hr · m ² · ° C). Best results are obtained when the conductive material is uniformly dispersed throughout the mortar composition. The composition is particularly effective for bonding refractory structures such as boiler tube shields and blocks to boiler tube assemblies.

Description of the Preferred Embodiments The compositions of the present invention generally comprise a refractory material, a conductive metal and a binder. The composition may also contain organic plasticizers and fillers.

Refractory materials useful herein include silicon carbide, silicon nitride and aluminum nitride. However, due to cost considerations, silicon carbide (Si
C) Mortar compositions are currently particularly effective at bonding silicon carbide refractory tube blocks or shields to metallic boiler tube assemblies and, as such, are currently available.
iC) is preferred. Most preferably, the refractory material component of the mortar is the same as, or at least comparable to, the refractory material used for the tube block or shield. This helps to prevent the formation of any significant amount of liquid material when the mortar is exposed to high temperatures during actual boiler or furnace operation. The refractory material is generally in an amount of about 5-90%, more preferably about 40-75%, most preferably about 50-65%, based on the total weight of the dry mortar composition. used.

The conductive metal is preferably copper or a copper alloy such as cupronickel (approximately Cu 65-80%, N 2.
i 35-20%), phosphor bronze, and monel (approximately Ni 70
%, Cu30%), but with that said other conductive metals such as silver, gold, nickel, inconel,
Materials such as nichrome, molybdenum, tungsten, niobium and tantalum, or alloys or mixtures thereof may be used. Conductive metals generally have a particle size of about 300 μm
Present in the form of less than metallic particles or flakes. The conductive metal is present in an amount of about 5 to 90% of the total weight of the dry mortar composition, more preferably about 10 to 60%, most preferably about 20 to 40%.

The binder used is preferably monoaluminum phosphate, aluminum orthophosphate, phosphoric acid,
Soluble phosphates such as alkali metal phosphates or alkaline earth metal phosphates. Other suitable binders useful herein include sodium silicate, potassium silicate and calcium aluminate cement. When the binder is a phosphate, it is generally in an amount of about 1-10%, more preferably about 2-8%, most preferably about 3% by total weight of the dry mortar composition. Present in an amount of ~ 7%. When the binder is a silicate, it is generally present in an amount of about 1-5%. If the binder is calcium aluminate cement, it generally
It is present in an amount of about 2-30%. When a liquid phosphate binder is utilized instead of a dry powder, it is generally about 1-6%, preferably about 2-4% P _{2 by} weight of the total mixture prior to the addition of water. It should have an O ₅ content.

Other materials that may be added to the composition include finely divided silica, clays such as bentonite and ball clay, and finely divided alumina. "Fine"
By means that the particles are generally smaller than about 44 μm in average particle size. These materials are generally present in amounts up to about 10%, more preferably up to about 8%.
Silica and alumina become part of the actual bond developed at the elevated temperatures experienced during mortar use. While clay enhances plasticity, it can also react with any free alumina, silica or phosphate present in the mortar composition and thus become part of the refractory bond. Thus, all of these additives serve to enhance the bond development when the mortar is subjected to operation and exposed to elevated temperatures, ie up to about 700 ° C.

Organic plasticizers may also be present in the composition to increase trowel suitability as well as mortar adhesion. Suitable organic plasticizers include, for example, methylcellulose, sodium or calcium lignosulfonates, dextrins, and polyacrylates, with methylcellulose and lignosulfonates being presently preferred. The organic plasticizer is generally present in an amount up to about 5% of the dry mortar composition, more preferably about 1 to 3% by weight.

The mortar composition is prepared by first mixing the dry ingredients in a suitable mixing device to form a homogeneous mixture, then adding any liquid ingredients and then adding water to the mixture. Dried ingredients may be dried in any suitable dry blender, such as Hobartland Castors.
(Hobart Landcaster) Blender, Muller blender, Erich blender, and the like can be mixed. This dry mixture is later
It can be stored with liquid ingredients, if any, and water. If a liquid ingredient, such as a liquid phosphate binder source, is used, it can be added to these dry ingredients when first mixing the dry ingredients, and this mixture is later added with water and It is stored in a sealed moisture-proof container until use. Alternatively, the liquid component can be added with water at the point of actual use. If this is done, the mixture is preferably about 15-60 to ensure complete mixing and dissolution of the soluble components, which improves the working properties of the mortar.
Let stand for a minute and then mix again before actually using.
Alternatively, the liquid components can be added simultaneously with the water and mixed until a homogeneous mixture is formed (generally about 5-10 minutes), and the resulting ready-to-use refractory mortar mixture is actually used. It can be stored in a sealed moisture-proof container until use. The water should generally be at a temperature above about 60 ° F (15.6 ° C), preferably about 70-90 ° F (21.1-32.2 ° C) at the time it is added. Although the amount of water to be used depends primarily on the particular physical consistency desired of the mortar, it is generally about 5-20% by weight of the dried mortar.
%, Preferably in the range of about 8-10%.

The present invention will now be described with respect to specific examples. In these examples, parts and percentages are by weight unless otherwise stated.

Example 1 57 parts of silicon carbide particles (less than 300 μm), 30 parts of copper particles (2
(Less than 00 μm), 5 parts ball clay particles, 5 parts dry monoaluminum phosphate, 0.15 parts alumina particles (45 μm
Dry blend of 0.85 parts of silica particles (less than 10 μm), 1.5 parts of calcium lignosulfonate and 0.5 parts of methylcellulose in a mixer until uniform. Add 9 parts of water at room temperature and mix for 10 minutes. The mortar is left for 30 minutes and mixed again just before use.

The resulting refractory mortar has a density of 3.00 g / cc after drying to a solid. Thermal conductivity is 270 BTU ・ in / hr ・ ft ²・ ° F (3350 kcal ・ cm /
hr · m ² · ° C).

Comparative Example A The procedure of Example 1 is repeated except that the copper particles are omitted and replaced with an equivalent amount of additional silicon carbide particles. The resulting refractory mortar is 33 BTU · in / hr ·
It shows the thermal conductivity of ft ² · ° F (410kcal · cm / hr · m ² · ° C).

Example 2 The procedure of Example 1 is repeated to produce another refractory mortar composition of the present invention. Their compositions are as shown below.

[0024]

[Table 1]

Composition A has a density of 2.77 g / cc and a thermal conductivity of
92 BTU ・ in / hr ・ ft ²・ ° F (1140kcal ・ cm / hr ・ m ²
・ C). Composition B has a density of 2.65 g / cc and a thermal conductivity of 60 BTU-in / hr-ft ^2- ° F (740 kcal-cm / hr-m ²
・ C).

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] June 11, 1991

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 16

[Correction method] Change

[Correction content]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 17

[Correction method] Change

[Correction content]

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 18

[Correction method] Change

[Correction content]

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical indication location C04B 35/66 T 7305-4G (72) Inventor Donald K. Ji Young Son USA, Masachi Youtsutsu 01520, Holden, Doyle Road 193

Claims (20)

[Claims] 1. A composition comprising a refractory material, a conductive metal and a binder. 2. The composition of claim 1, wherein the conductive metal is uniformly dispersed throughout the composition. 3. The conductive metal is copper, silver, gold, nickel, molybdenum, tungsten, niobium and tantalum,
And the composition of claim 1 selected from the group consisting of and alloys and mixtures thereof. 4. The conductive metal is copper or cupronickel containing about 65-80% Cu and 35-20% Ni, phosphor bronze, and about 70% Ni and 30% Cu. The composition of claim 1 which is a copper alloy selected from the group consisting of: Monel (TM). 5. The composition of claim 1, wherein the conductive metal is present in the form of particles having a particle size of less than about 300 μm. 6. The composition of claim 1, wherein the refractory material is selected from the group consisting of silicon carbide, silicon nitride and aluminum nitride. 7. The composition of claim 1, wherein the refractory material is silicon carbide. 8. The binder is a phosphate-based material,
The composition of claim 1. 9. The composition of claim 8 wherein said phosphate material is selected from the group consisting of monoaluminum phosphate, aluminum orthophosphate and phosphoric acid. 10. The composition of claim 1, further comprising a filler. 11. The filler is selected from the group consisting of alumina, silica, clay and mixtures thereof.
The composition as described. 12. The composition of claim 10, wherein the filler is present in an amount up to about 10% by weight. 13. The method of claim 1, further comprising an organic plasticizer.
The composition as described. 14. The composition of claim 13, wherein the organic plasticizer is selected from the group consisting of methyl cellulose, sodium or calcium lignosulfonate, dextrin, polyacrylate polymers and mixtures thereof. 15. The composition of claim 13, wherein the organic plasticizer is present in an amount of about 1-5% by weight. 16. The refractory material is present in an amount of about 5 to 90% by weight, based on the total weight of the refractory material and the metal, and the conductive metal is based on the total weight of the refractory material and the metal. The composition of claim 1 wherein said binder is present in an amount of about 5-90% by weight and said binder is present in an amount sufficient to render said composition a refractory mortar. 17. The refractory material is present in an amount of about 40-75 wt% based on the total weight of the refractory material and the metal, and the conductive metal is based on the total weight of the refractory material and the metal. The composition of claim 1 wherein the binder is present in an amount of about 10 to 60% by weight and the binder is present in an amount sufficient to render the composition a refractory mortar. 18. The refractory material is present in an amount of about 50-65% by weight, based on the total weight of the refractory material and the metal, and the conductive metal is based on the total weight of the refractory material and the metal. The composition of claim 1 wherein the binder is present in an amount of about 20-40% by weight and the binder is present in an amount sufficient to render the composition a refractory mortar. 19. The composition according to claim 1, wherein the conductive metal is copper or a metal alloy containing copper, and the refractory material is silicon carbide. 20. About 57 parts silicon carbide, about 30 parts copper or copper alloy, about 5 parts monoaluminum phosphate, about 0.15 parts fine alumina, about 0.85 parts fine silica, about 5 parts. Clay, about 1.5 parts calcium lignosulfonate, and about 0.
A composition comprising 5 parts of methyl cellulose.