Heat exchanger device with heat-radiative coating

Abstract

A heat retainer for a hot blast stove of a blast furnace, the heat retainer adapted to function without decomposition at temperatures of about 1200° C., wherein: at least one surface of said heat retainer is coated with a high radiative and highly-emissive material forming said coating layer; the thickness of said coating layer is critically between 0.02 mm and 3 mm; the heat retainer absorbs energy or emits energy mainly by radiation; and energy of radiation is mainly at a wavelength of 1-5 μm.

1 . A heat retainer for a hot blast stove of a blast furnace, the heat retainer adapted to function at temperatures of about 1200° C. present during operation of a hot blast stove of a blast furnace, and adapted to absorb thermal energy from air in the hot blast stove of the blast furnace, the heat retainer experiencing a heat storage period and a heat release period, the heat retainer having a coating layer, 
       wherein:
 at least one surface of said heat retainer is coated with a high radiative material forming said coating layer; 
 the thickness of said coating layer is critically between 0.02 mm and 3 mm; 
 the heat retainer absorbs energy in the heat storage period, whereby end temperature of the heat retainer is increased during heat storage period compared to what it would have been in the absence of said coating layer; 
 the heat retainer emits energy in the heat release period, whereby end temperature of the heat retainer is decreased during heat release period compared to what it would have been in the absence of said coating layer; 
 the heat retainer absorbs energy or emits energy mainly by radiation at a wavelength of between 1 and 5 μm. 
 
     
     
         2 . The heat retainer of  claim 1 , wherein said coating layer achieves rapid and efficient heat transfer and increases the heat storage capacity of the heat retainer. 
     
     
         3 . The heat retainer of  claim 1 , wherein said high radiative material is not highly-reflective. 
     
     
         4 . The heat retainer of  claim 1 , adapted to transfer more heat by radiation than by convection. 
     
     
         5 . The heat retainer of  claim 1 , adapted to absorb and emit heat non-simultaneously, wherein a steady-state for heat absorption and emission is not reached during a heat absorption period or a heat emission period. 
     
     
         6 . The heat retainer of  claim 1 , comprising a core and a coating layer, wherein the heat emissivity of the coating layer is greater than the heat emissivity of the core. 
     
     
         7 . The heat retainer of  claim 6 , wherein said coating layer increases heat absorption and heat radiation ability of the core. 
     
     
         8 . The heat retainer of  claim 6 , further comprising at least one cavity in said core. 
     
     
         9 . The heat retainer of  claim 8 , wherein said cavity passes through the matrix from its one end to another and said coating layer completely coats the surface of said cavity. 
     
     
         10 . The heat retainer of  claim 1 , wherein the substrate of the heat retainer is made of one of a refractory material, or a ceramic material. 
     
     
         11 . The heat retainer of  claim 1 , wherein said coating layer comprises one or more of the following: Cr 2 O 3 , clay, montmorillonite, brown corundum, silicon carbide, TiO 2 , Al 2 O 3 , aluminum hydroxide, zirconium oxide, phosphoric acid, or hydrated sodium silicate gel. 
     
     
         12 . A heat retainer comprising: a core having a first heat emissivity; a plurality of inner passages in said core, said plurality of said inner passages extending from a first surface of said core to a second surface of said core, and being immovable with respect to one another; and a coating layer coating said core and said passages, said coating layer having a second heat emissivity; wherein said coating layer comprises a high radiative material; the thickness of said coating layer is critically between 0.02 mm and 3 mm; said second heat emissivity is greater than said first heat emissivity; said coating layer achieves rapid and efficient heat transfer and increases the heat storage capacity of the heat retainer; said high radiative material is not highly-reflective; said heat retainer is adapted to absorb heat from and to emit heat to air in a hot blast stove of a blast furnace mainly by thermal radiation; said heat retainer is adapted to absorb and emit heat non-simultaneously; said heat retainer is adapted for use in a high temperature heat exchanger and for use at temperatures below 1400° C. present during operation of a hot blast stove of a blast furnace; the heat retainer experiences a heat storage period and a heat release period; the heat retainer absorbs energy in the heat storage period, whereby end temperature of the heat retainer is increased during heat storage period relative to what it would have been without said coating layer; the heat retainer emits energy in the heat release period, whereby end temperature of the heat retainer is decreased during heat release period relative to what it would have been without said coating layer; and energy of thermal radiation is mainly at a wavelength of between 1 and 5 μm. 
     
     
         13 . The heat retainer of  claim 1 , wherein said coating layer achieves rapid and efficient heat transfer and increases the heat storage capacity of the heat retainer. 
     
     
         14 . The heat retainer of  claim 1 , wherein said high radiative material is not highly-reflective. 
     
     
         15 . The heat retainer of  claim 1 , adapted to transfer more heat by radiation than by convection. 
     
     
         16 . The heat retainer of  claim 1 , adapted to absorb and emit heat non-simultaneously. 
     
     
         17 . The heat retainer of  claim 1 , comprising a core and a coating layer, wherein the heat emissivity of the coating layer is greater than the heat emissivity of the core. 
     
     
         18 . The heat retainer of  claim 6 , wherein said coating layer increases heat absorption and heat radiation ability of the core. 
     
     
         19 . The heat retainer of  claim 6 , further comprising at least one cavity in said core. 
     
     
         20 . The heat retainer of  claim 8 , wherein said cavity passes through the matrix from its one end to another and said coating layer completely coats the surface of said cavity. 
     
     
         21 . A method for enhancing radiative heat absorption and radiative heat emission and for simultaneously reducing heat reflection in a heat retainer for a hot blast stove of a blast furnace, comprising: placing into a hot blast stove of a blast furnace a core coated with a coating layer, and operating said hot blast stove or said blast furnace at usual operating temperatures about 1200° C.; wherein said core has a first heat emissivity; said coating layer has a second heat emissivity; said second heat emissivity is greater than said first heat emissivity; said coating layer comprises a high radiative material; the thickness of said coating layer is critically between 0.02 mm and 3 mm; said coating layer achieves rapid and efficient heat transfer and increases the heat storage capacity of the heat retainer; said high radiative material is not highly-reflective; said heat retainer absorbs heat from and emits heat to air in a hot blast stove of a blast furnace mainly by thermal radiation; said heat retainer absorbs and emits heat non-simultaneously; the heat retainer experiences a heat storage period and a heat release period; the heat retainer absorbs energy in the heat storage period, whereby end temperature of the heat retainer is increased during heat storage period; the heat retainer emits energy in the heat release period, whereby end temperature of the heat retainer is decreased during heat storage period; and energy of thermal radiation is mainly in a wavelength of 1-5 μm.