Heat Storage Device with Heat-Radiative Coating

Abstract

Taught herein is a heat retainer for a heat exchanger the retainer having a coating layer. At least one surface of the heat retainer is coated with a highly-radiative material forming a coating layer whose emissivity is greater than that of a substrate material of which the core of the heat retainer is made. The heat retainer is in the shape of a honeycomb, a fin, a ball, an ellipse or a plate, and one or a plurality of inner holes are disposed therein. The substrate of which the heat retainer is made is a refractory material, a ceramic material or a steel material. The heat retainer has comparatively good heat absorption and emission performance; heat storage capacity is increased, diathermancy is improved, and energy is saved.

Description

FIELD OF THE INVENTION

The invention relates to a heat exchanger and more particularly to a heat exchanger with a highly-radiative coating layer facilitating heat exchange.

DESCRIPTION OF THE RELATED ART

In industrial fields such as metallurgy, machinery and farm product processing, heat exchangers are commonly-used. The main function of a heat exchanger is to transfer heat to air or gas. One type of heat exchangers uses coal, gas, oil or electricity as a direct heat source. Another type of heat exchangers employs secondary sources of heat. A heat source firstly transfers energy to a heat retainer of the heat exchanger, and then air or gas that needs to be heated is passed over it. During heat exchange between the heat retainer and air or gas, heat is removed from the heat retainer, and air or gas is heated. Generally, the heat retainer is made of a refractory material, a ceramic material, an iron or a steel material.

Heat absorption and emission capability of heat retainers is an important factor for the heat exchange performance of a heat exchanger, and is directly associated with power savings. To improve the heat exchange efficiency of a heat exchanger, a plurality of patents, such as CN2462326Y and CN2313197Y, provide structural improvements. However, a heat exchanger employing a coating layer made of highly radiative material has not heretofore been proposed to improve the heat storage capability of the heat retainer and, in turn, to improve the efficiency of the heat exchanger.

SUMMARY OF THE INVENTION

To overcome the deficiencies of prior art, it is one objective of the invention to provide a highly-efficient and energy-saving heat retainer with a coating layer for facilitating heat exchange.

The invention provides a heat retainer with a coating layer for facilitating heat exchange, wherein at least one surface of the heat retainer is coated with a coating layer made of a highly-radiative material.

The thickness of the highly-radiative material coating layer is 0.02-3 mm.

The emissivity of the highly-radiative material is greater than that of the substrate material of which the core of the heat retainer is made.

Advantageously, the highly-radiative material is a material having an absorption rate and an emission rate higher than those of the substrate material of which the core of the heat retainer is made.

The heat retainer takes the shape of a honeycomb, a fin, a ball, an ellipse or a plate.

One or a plurality of inner holes is disposed within the heat retainer. The inner hole is circular, square, rectangular, rhombic, hexagonal or polygonal. The substrate of the heat retainer is made of a refractory material, a ceramic material, an iron or a steel material.

A cross section of the heat retainer is circular, square, rectangular, rhombic, hexagonal or polygonal.

The highly-radiative material is any suitable highly-radiative far-infrared material suitable for a heat retainer made of a refractory material, a ceramic material or a steel material.

The coating layer made of highly-radiative material is implemented by way of paste-coating, spray-coating or dip-coating, and the heat retainer having the coating layer is used directly after coating, or is used after high temperature curing.

Surfaces of the substrate of the heat retainer are pre-treated with a pre-treating liquid prior to being paste-coated, spray-coated or dip-coated with the highly-radiative material, so as to further improve adhesion between the highly-radiative material and the substrate.

The pre-treating liquid is an aqueous solution containing polyamine curing agent PA80 (PA80 adhesive) or an alkali metal silicate.

Solid components in the highly-radiative material are hyperfinely processed, so as to enable the particle size to be 20-900 nm, and to improve adhesion between the highly-radiative material and the substrate.

Surfaces of the heat retainer for the heat exchanger of the invention are coated with a coating layer of highly-radiative material whose emissivity is greater than that of the substrate material of which the core of the heat retainer is made; the heat absorption and emission capability of the heat exchanger is increased, which improves heat absorption and emission of the heat retainer, and increases the heat storage capacity.

Meanwhile, increasing the heat exchange efficiency of the heat exchanger also saves energy. Particularly, when a checker brick of a hot blast stove of a blast furnace is coated with the highly radiative material, temperature inside the hot blast stove is uniformly distributed, and the heat storage capacity is notably increased. This raises the temperature of the circulating air, shortens the startup period, and reduces the gas amount and air flow. Reduction of the gas amount and the air flow further saves energy, lowers the requirement of a wind turbine, and reduces the overall cost of devices. The coating layer of the heat retainer also operates to protect the substrate of which the core of the heat retainer is made. When the surfaces of the heat retainer of a steel-rolling regenerative furnace are coated with the highly-radiative material, temperature inside the heat retainer increases significantly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating a honeycomb-shaped heat retainer with a coating layer for a heat exchanger according to one embodiment of the invention;

FIG. 2 is a diagram illustrating a honeycomb-shaped heat retainer with a coating layer for a heat exchanger according to another embodiment of the invention;

FIG. 3 is a diagram illustrating a fin-shaped heat retainer with a coating layer for a heat exchanger according to another embodiment of the invention;

FIG. 4 is a partial cross-sectional view illustrating a plate-shaped heat retainer with a coating layer for a heat exchanger according to yet another embodiment of the invention;

FIG. 5 is a partial cross-sectional view illustrating a ball-shaped heat retainer with a coating layer for a heat exchanger according to yet another embodiment of the invention;

FIG. 6 is a diagram illustrating an elliptical heat retainer with a coating layer for a heat exchanger according to yet another embodiment of the invention; and

FIG. 7 is a partial cross-sectional view illustrating a non-metal heat retainer with a coating layer for a heat exchanger according to yet another embodiment of the invention.

In the drawings: 1-circular inner hole; 2-highly-radiative material coating layer; 3-circuilar inner hole; 4-highly-radiative material coating layer; 5-rectangular inner hole; 6-highly-radiative material coating layer; 7-highly-radiative material coating layer; 8-substrate; 9-heat exchange surface; 10-substrate; 11-highly radiative material coating layer; 12-heat exchange surface; 13-substrate; 14-highly radiative material coating layer; 15-heat exchange surface.

DETAILED DESCRIPTION OF THE INVENTION

Embodiment 1

As shown in FIG. 1, a heat retainer used for a hot blast stove of a blast furnace is a checker brick. The checker brick (heat retainer) has a plurality of circular inner holes 1, and all surfaces (comprising those of the inner holes) of the check brick (heat retainer) are coated with a coating layer of a highly radiative material 2 whose thickness is 0.02 mm. A substrate of the heat retainer is a refractory material, and the highly-radiative material coating layer 2 is a highly-radiative material whose emissivity in the far-infrared region is greater than that of a substrate material of the heat retainer. The highly-radiative material coating layer 2 comprises by weight: 110 parts of Cr₂O₃, 80 parts of clays, 90 parts of montmorillonites, 300 parts of brown corundums, 100 parts of silicon carbides, 400 parts of PA80 adhesive and 100 parts of water. These components are hyperfinely processed, so as to enable the particle size to be in the 25-700 nm range. Compared with existent heat exchangers, the heat exchanger of this embodiment saves over 20% of energy.

Embodiment 2

As described in embodiment 1, except that differences are as follows: the cross section of the honeycomb-shaped heat retainer is rectangular; and the highly-radiative material coating layer is disposed within a plurality of circular inner holes 3 (as shown in FIG. 2).

Embodiment 3

As shown in FIG. 3, the heat retainer for a heat exchange is fin-shaped. A plurality of rectangular inner holes 5 are disposed in the heat retainer, and all surfaces (comprising surfaces of the inner holes) of the heat retainer for the heat exchanger are paste-coated with a highly-radiative material coating layer 6 whose thickness is 0.03 mm. A substrate of the heat retainer is a ceramic material, and the highly-radiative material coating layer 4 is a highly-radiative material whose far-infrared emissivity is greater than that of a substrate material of the heat retainer. The highly-radiative material comprises by weight: 15 parts of zirconium oxide, 8 parts of Cr₂O₃, 10 parts of TiO₂, 2 parts of montmorillonites, 15 parts of Al₂O₃, 10 parts of carborundums, 30 parts of PA80 adhesives, and 10 parts of water. Compared with existent heat exchangers, the heat efficiency of the heat exchanger according to this embodiment is improved by over 10%.

Embodiment 4

As shown in FIG. 4, the heat retainer for use in a heat exchanger according to this embodiment is plate-shaped; and the surfaces of the heat retainer are paste-coated with a coating layer 7 made of a highly-radiative material and whose thickness is 0.1 mm. A substrate 8 of the heat retainer is an iron and a steel material, and the highly-radiative material is a highly-radiative material whose far-infrared emissivity is greater than that of the substrate material. The highly-radiative material comprises by weight: 60 parts of Cr₂O₃, 200 parts of brown corundums, 50 parts of clays, 30 parts of montmorillonites, 200 parts of silicon carbides, 200 parts of hydrated sodium silicate gels, and 100 parts of water. The outer surface of the coating layer 7 is the heat exchange surface 9. The surfaces of the heat retainer are coated with a pre-treating liquid prior to being paste-coated with the highly-radiative material. The pre-treating liquid comprises 10% aqueous solution (by weight) of hydrated sodium silicate gels. Compared with existent heat exchangers, the heating efficiency of the heat exchanger of this embodiment is improved by over 10%.

Embodiment 5

As shown in FIG. 5, the heat retainer for a heat exchanger is ball-shaped, and the surfaces of the heat retainer are paste-coated with a highly-radiative material resulting in a coating layer 11 whose thickness is 2 mm. An outer surface of the coating layer 7 is the heat exchange surface 12. A substrate 10 of the heat retainer is a refractory material, and the highly-radiative material forming the coating layer 11 is a highly-radiative material whose far-infrared emissivity is greater than that of a substrate material. The highly-radiative material comprises by weight: 5 parts of zirconium oxide, 10 parts of silicon carbides, 5 parts of titanium, 3 parts of clays, 40 parts of brown corundums, 10 parts of aluminum hydroxides, 15 parts of phosphoric acid, and 12 parts of water. Compared with existent heat exchangers, the relative temperature of the heat exchanger of this embodiment is increased by over 15° C. The heat retainer according to this embodiment is applicable for use as a regenerative furnace, in which the ball-shaped heat retainer exchanges heat within a heat accumulator being part of the regenerative furnace.

Embodiment 6

As described in embodiment 5, except that the heat retainer for a heat exchanger is elliptical in shape (as shown in FIG. 6).

Embodiment 7

The surfaces of a ball-shaped heat retainer are spray-coated with a highly-radiative material giving rise to a coating layer whose thickness is 2.5 mm. The coating layer comprises by weight: 15 parts of silicon carbides, 2 parts of brown corundums, 35 parts of zirconias, 2 parts of montmorillonites, 6 parts of chromium oxides, 27 parts of PA80 adhesives and parts of 13 water.

The surfaces of the heat retainer are coated with pre-treating liquid prior to being spray-coated with the highly-radiative material, The pre-treating liquid comprises 10% aqueous solution (by weight) of PA80 adhesive.

Embodiment 8

As shown in FIG. 7, the surfaces of a ceramic substrate 13 of a heat retainer are paste-coated with a highly-radiative material resulting in a coating layer 14 whose thickness is 3 mm. The outer surface of the coating layer 14 is the heat exchange surface 15. The coating layer comprises by weight: 60 parts of Fe₂O₃, 5 parts of zirconias, 20 parts of hydrated sodium silicate gels and 15 parts of water. The surfaces of the heat retainer are coated with a pre-treating liquid prior to being paste-coated with the highly-radiative material coating layer. the pre-treating liquid comprising a 8% by weight aqueous solution of hydrated sodium silicate gels.

The highly-radiative material forming a coating layer on the heat retainer may be freely selected. The above embodiments are intended to be illustrative only, and are not meant to limit the invention.

Claims

1. A heat retainer for a heat exchanger the heat retainer having a coating layer, wherein at least one surface of said heat retainer is coated with a highly-radiative material forming said coating layer.

2. The heat retainer of claim 1, wherein a thickness of said coating layer is 0.02-3 mm.

3. The heat retainer of claim 1, wherein an emissivity of said highly-radiative material is greater than that of a substrate material of which the heat retainer is made.

4. The heat retainer of claim 1, wherein the heat retainer is in the shape of a honeycomb, a fin, a ball, an ellipse or a plate.

5. The heat retainer of claim 1, comprising one or a plurality of inner holes disposed within said heat retainer.

6. The heat retainer of claim 5, wherein the inner hole may be circular, square, rectangular, rhombic, hexagonal or polygonal.

7. The heat retainer of claim 1, wherein a cross section of the heat retainer is circular, square, rectangular, rhombic, hexagonal or polygonal.

8. The heat retainer of claim 1, prepared by coating surfaces of the substrate of the heat retainer with a pre-treating liquid and then paste-coating, spray-coating or dip-coated with the highly-radiative material to form a coating layer, wherein the pre-treating liquid is an aqueous solution of the polyamine curing agent PA80 or an alkali metal silicate.

9. The heat retainer of claim 1, wherein the substrate of the heat retainer is made of a refractory material, a ceramic material, an iron and a steel material.