CATALYTIC REFRACTORY HEATING APPLIANCE

Abstract

A catalytic refractory heating appliance includes a body formed from a silicon carbide refractory material having a porosity that permits ionic oxygen to pass through the refractory material. The body defines a gas flow channel. A catalyst coating is on a surface of the refractory material of the body, whereby the refractory material becomes an active component with catalytic capability. For example, when the catalytic refractory heating appliance is a fire tube carbon dioxide and sulfur compounds can be directly absorbed, or carbon monoxide is reduced to methane.

Claims

1. A catalytic refractory heating appliance, comprising: a body formed from a silicon carbide refractory material having a porosity that permits ionic oxygen to pass through the refractory material, the body defining a gas flow channel; and a catalyst coating a surface of the refractory material of the body, whereby the refractory material becomes an active component with catalytic capability.

2. The catalytic refractory heating appliance of claim 1, wherein the body is tubular.

3. The catalytic refractory heating appliance of claim 2, wherein the body is a fire tube.

4. The catalytic refractory heating appliance of claim 1, wherein the body is formed of conductive nitride-bonded silicon carbide refractory material.

5. The catalytic refractory heating appliance of claim 1, wherein the catalyst coating is a metal oxide framework catalyst.

6. The catalytic refractory heating appliance of claim 1, wherein the catalyst coating is a metal oxide framework of calcium and magnesium oxide layers interconnected with an iron oxidation pathway for oxygen.

7. The catalytic refractory heating appliance of claim 6, wherein the catalyst coating is a dolomitic limestone whitewash.

8. The catalytic refractory heating appliance of claim 1, wherein a metallic vapor coating is positioned on the silicon carbide refractory material.

9. The catalytic refractory heating appliance of claim 8, wherein the metal vapor coating is combined with the catalyst coating.

10. The catalytic refractory heating appliance of claim 9, wherein the metal vapor coating is comprised of a majority of lead sulfide with bismuth trioxide.

11. A catalytic refractory heating appliance, comprising: a body formed from a conductive nitride-bonded silicon carbide refractory material having a porosity that permits ionic oxygen to pass through the refractory material, the body being tubular and defining a gas flow channel; and a metal oxide framework catalyst coating a surface of the refractory material of the body, whereby the refractory material becomes an active component with catalytic capability.

12. The catalytic refractory heating appliance of claim 11, wherein the metal oxide framework catalyst coating is of calcium and magnesium oxide layers interconnected with an iron oxidation pathway for oxygen.

13. The catalytic refractory heating appliance of claim 11, wherein a metal vapor coating is combined with the metal oxide framework catalyst coating.

14. The catalytic refractory heating appliance of claim 13, wherein the metal vapor coating is comprised of a majority of lead sulfide with bismuth trioxide.

Description

DESCRIPTION OF THE DRAWINGS

[0017] Reference is now made to the accompanying drawings, in which:

[0018] FIG. 1 is a depiction of a crystal structure of calcite; and

[0019] FIG. 2 is a depiction of a crystal structure of dolomite; and

[0020] FIG. 3 is a perspective view of a tubular body of catalytic refractory material; and

[0021] FIG. 4 is a side elevation view of the tubular body of FIG. 3 incorporated into a catalytic refractory heating appliance.

DETAILED DESCRIPTION

[0022] Aspects of various embodiments are described in relation to the figures.

[0023] A catalytic refractory, generally identified by reference numeral 10, will now be described with reference to FIG. 1 through FIG. 4.

Structure and Relationship of Parts

[0024] Nitride bonded silicon carbide material withstands extreme heat and does not disintegrate when exposed to oxygen. Due to the firing process the resulting silicon carbide material has a porosity that permits ionic oxygen to pass through the refractory materials. By modifying the porosity of the refractory and coating the surface of the refractory with a catalyst, the refractory becomes an active component with catalytic capability. For example, a fire tube can be coated with a metal oxide framework (MOF) catalyst whereby carbon dioxide and sulfur compounds can be directly absorbed, or carbon monoxide is reduced to methane.

[0025] Referring to FIG. 1, a typical natural limestone or the calcium carbonate is calcined to form calcite, a refractory material. Naturally occurring limestone deposits exposed to magnesium rich water over time form a different material known as dolomitic limestone, shown in FIG. 2. Dolomite refractories mainly consist of calcium magnesium carbonate. Typically, dolomite refractories are used in converter and refining furnaces. FIG. 2 shows Ca(Mg, Fe)(CO.sub.3).sub.2.

[0026] A variation in the dolomitic limestone containing calcium magnesium carbonate forms when iron carbonate is added prior to calcining to form a metal oxide framework of calcium and magnesium oxide layers interconnected with an iron oxidation pathway for oxygen. This catalyst has been demonstrated to reduce up to 80 percent of the carbon dioxide to carbon monoxide while the oxygen oxidizes the iron.

[0027] Referring to FIG. 3, catalytic refractory 10 consists of a nitride bonded silicon carbide body 20, coated with a MOF catalyst coating of dolomitic limestone whitewash (MOF catalyst 30), and calcined at 700 C. for 20 minutes and then cooled for a 20-minute cooling period. As will hereinafter be described, catalytic refractory 10 is engineered to define a gas flow channel for secondary heat recovery to preheat combustion air. Maximum efficiency is obtained in secondary heat recovery incorporating these refractory elements.

[0028] Referring to FIG. 4, hydrocarbon fuel 40 is fed into catalytic refractory heating appliance 50, into which has been incorporated the catalytic refractory 10. When the hydrocarbon fuel is ignited, hot carbon dioxide 60 enters the pore space of the MOF catalyst 30, in a manner similar to the manner in which carbon dioxide is received by leaves on a tree. Carbon dioxide 60 dissociates into carbon monoxide 70 and an oxygen ion. The oxygen ion bonds with the iron forming iron oxide while the carbon monoxide leaves the MOF catalyst 30.

[0029] When heating appliance 50 is shut down, catalytic refractory 10 cools. As MOF catalyst 30 cools it continues to adsorb carbon dioxide from the atmosphere provided the humidity is above a minimum % relative humidity (RH). Regeneration of catalytic refractory 10 coated with MOF catalyst 30 occurs each cycle upon reheating the appliance. In order to increase the number of regeneration cycles and therefore the longevity of MOF catalyst 30, the electrons required to reduce the iron oxide are supplied by a metallic vapor coating 80, between the MOF and the conductive nitride bonded silicon carbide structure. This metal vapor coating consists of a base material consisting of a majority of lead sulfide and bismuth trioxide combined with the dolomitic limestone and iron carbonate prior to calcining the applied whitewash coating.

[0030] The embodiments described in this document provide non-limiting examples of possible implementations of the present technology. Upon review of the present disclosure, a person of ordinary skill in the art will recognize that changes may be made to the embodiments described herein without departing from the scope of the present technology. Practical implementation of the features may incorporate a combination of some or all of the aspects, and features described herein should not be taken as indications of future or existing product plans.