JPH0229959B2 - NETSUKOKANKI - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat exchanger, and particularly to a heat exchanger for recovering heat from exhaust gas generated in a heating furnace, heat treatment furnace, or the like.

Generally, in heating furnaces, heat treatment furnaces, etc., a huge amount of thermal energy is lost through exhaust gas. Therefore, a heat exchanger is installed in the flow path of the exhaust gas, the exhaust gas is transferred to the air passed through the heat exchanger, and this heated air is used for the primary air of the burner or for preheating the object to be heated. In particular, it has been conventional practice to effectively utilize the heat of exhaust gas.

However, when trying to increase heat recovery efficiency with such a heat exchanger, conventional methods only focused on widening the heat transfer area in the heat exchanger.
Problems such as increased equipment size, increased production costs, and space requirements arose. Therefore, as the price of thermal energy continues to rise, there is a strong demand for heat exchangers that have good heat recovery efficiency, are small in size, and require little equipment cost.

The present invention has been made in view of these points, and next, one embodiment of the present invention will be described with reference to FIG. Reference numeral 1 denotes a passage for exhaust gas, and numeral 2 denotes an air-permeable solid which is curved and stretched in the flow direction of the exhaust gas so as to close the passage 1. Here, the term "breathable solid" refers to a solid formed from a heat-resistant material such as metal or ceramic into a shape having a net shape, a honeycomb shape, a fibrous shape, a porous shape, or the like. Reference numeral 3 denotes a heat recovery pipe installed on the inflow side of the breathable solid 2 at a predetermined interval so as to be surrounded by the breathable solid 2. The inside of the heat recovery tube 3 is filled with heat-resistant granules 4, .

The fluid to be heated, such as air for circulation in the furnace, flowing through the heat recovery pipe 3 is guided into the heat recovery pipe 3 through an inlet 5 provided at one end of the heat recovery pipe 3, and the granules are 4, 4... After passing through the gap 6 existing between,
The heat recovery tube 3 is configured to be sent out from an outlet 7 provided at the other end of the heat recovery tube 3 .

Since the present invention has the above-described configuration, the exhaust gas flowing in the direction of the arrow in the flow path 1 passes through the air permeable solid 2 installed in the flow path 1. Heating the solid to a high temperature.
Then, the exhaust gas itself is deprived of heat by the breathable solid 2, lowers its temperature, and flows out to the outside. In this case, the inflow side of the breathable solid 2 is heated to a higher temperature than the outflow side, so that more radiant heat energy is radiated toward the heat recovery pipe 3 installed on the inflow side of the breathable solid 2.

Thus, the radiant heat radiated from the breathable solid 2 toward the heat recovery tube 3 is transferred from the outer surface to the inner surface of the heat recovery tube 3. At this time, when the fluid to be heated is made to flow through the heat recovery pipe 3, the fluid to be heated is heated by the radiant heat radiated by the breathable solid 2 transferred to the inner surface of the heat recovery pipe 3. The radiant heat transferred to the inner surface of the heat recovery pipe 3 is transferred to the particles 4,
By heating 4... and causing heat transfer between the particles 4, 4..., or by heat transfer between the heated fluid once warmed by radiant heat and the particles 4, 4...,
Furthermore, due to the turbulent flow or meandering passage of the fluid to be heated in the heat recovery pipe 3, the radiant heat is transferred to the particles 4, 4...
Since the heat is transferred throughout the heat recovery tube 3, the heated fluid is heated not only at the inner periphery of the heat recovery tube 3, but also throughout the heat recovery tube 3 until it flows through the center.

On the other hand, the exhaust gas flowing through the flow path 1 passes around the heat recovery tube 3 before flowing into the air permeable solid 2, but at this time too, the heat of the exhaust gas is directed from the outer surface to the inner surface of the heat recovery tube 3. communicated. Therefore, the fluid to be heated can recover both the radiant heat emitted from the breathable solid 2 and the heat transferred directly from the exhaust gas to the heat recovery pipe 3.

FIG. 2 shows another embodiment of the present invention,
In the figure, the inside of the heat recovery tube 3 is partitioned halfway into two chambers 9a and 9b by a partition wall 8. The fluid to be heated is then introduced into the chamber 9 in the heat recovery pipe 3 through the inlet 5.
After passing through each of the chambers 9a and 9b, the heat is sent out from the outlet 7 to the outside of the heat recovery pipe 3.

Note that the present invention is not limited to the configuration shown in this embodiment; for example, if fins (not shown) are provided protruding from the outer periphery of the heat recovery tube 3, the heat recovery efficiency can be further improved. Further, the particles 4 do not necessarily have to be spherical, and it is sufficient that the fluid to be heated can effectively flow through the heat recovery tube 3, so they may be square or irregularly shaped. Further, the size of the particles 4 is not particularly limited, and may be a mixture of sizes. However, if pressure loss due to the heated fluid flowing through the heat recovery tube 3 is a problem, selecting spherical particles of a certain size will reduce the gap in the heat recovery tube 3. Since it can be maintained uniformly over the entire area, the fluid to be heated can pass through smoothly. Further, the material used for the grains 4 is not limited to ceramic materials, and various heat-resistant materials can be used.

The heat exchanger is installed so that the fluid to be heated is parallel to, opposite to, or perpendicular to the flow of exhaust gas.

As is clear from the above explanation, in the present invention, a breathable solid is provided in the exhaust gas flow path, and a heat recovery pipe is provided on the inflow side so as to be surrounded by the breathable solid. As a result, the air-permeable solid is heated, and radiant heat is radiated from the air-permeable solid to the heat recovery tube, and a large amount of thermal energy is absorbed into the heat recovery tube not only by heat transfer through direct contact with the exhaust gas but also by radiation.

Furthermore, the heat recovery tube is filled with particles of an appropriate size,
Since the fluid to be heated flows through the gaps between the granules, the heat absorbed in the heat recovery tube is efficiently transferred to the fluid to be heated through the granules, resulting in extremely high heat exchange efficiency as a whole. It is something that improves things.

In addition, it has a relatively simple structure and has various advantages such as low manufacturing cost of the heat exchanger.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view showing one embodiment of the heat exchanger according to the present invention, and FIG. 2 is a longitudinal cross-sectional view showing another embodiment of the heat exchanger according to the present invention. 1... Channel, 2... Air permeable solid, 3... Heat recovery tube, 4, 4... Particles, 6... Gap.

Claims (1)

[Claims] 1 In addition to providing a breathable solid in the exhaust gas flow path,
A heat recovery pipe is provided on the inflow side of the air permeable solid so as to be surrounded by the air permeable solid, and the heat recovery pipe is filled with appropriately sized heat-resistant granules such as ceramic material. A heat exchanger characterized in that it is configured to allow a fluid to be heated to flow through a gap between the heat exchangers.