JPS6261643B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a preheating device for preheating a material to be heated in a heating furnace, a heat treatment furnace, or the like.

Conventionally, in heating furnaces, heat treatment furnaces, etc. (hereinafter collectively referred to as heating furnaces) that perform heating or heat treatment of materials to be heated, a preheating chamber is provided by extending the length of the furnace on the side where the material to be heated is charged, and the inside of the preheating chamber is A preheating device has been proposed that sprays exhaust gas from a furnace onto a passing material to be heated to preheat it by convection heat transfer. However, as the exhaust gas in this furnace is the high-temperature exhaust gas that has passed through the furnace while heating the furnace walls and materials to be heated mainly through convective heat transfer, it is possible to dissipate heat with a large amount of heat transfer to the materials to be heated. There is a problem in that sufficient heating is not performed in the furnace, and high thermal efficiency cannot be obtained even when combined with jet preheating.

The present invention has been made in view of the above points, and it is an object of the present invention to provide a preheating device for a heated material that has excellent heating characteristics for the heated material in a furnace and can provide high thermal efficiency.

An embodiment of the present invention will be described below with reference to the drawings.

In the figure, 1 is a walking beam heating furnace, 2
is a walking beam, which moves in a rectangular or elliptical shape by a known mechanism (not shown). 3 is a heating chamber of the heating furnace, and 4 is a burner.
Reference numeral 5 denotes a preheating chamber which is provided with an extended furnace length on the heating material charging side of the heating chamber 3, and a plenum chamber having a large number of ejection holes 6 facing the heating material W on the walking beam 2 is installed in the ceiling of the preheating chamber. 7 is permanently installed. Reference numeral 8 denotes an exhaust gas pipe line that communicates the heating chamber 3 and the plenum chamber 7, and a high temperature fan 9 for pressurizing the exhaust gas is provided in the middle of this pipe line. 10 is a heat insulating material that covers the outer periphery of the exhaust gas pipe line 8. Reference numeral 11 denotes a partition made of a breathable solid material, which is provided to cover the opening 12 of the exhaust gas pipe 8 into the heating chamber 3, and 13 is a heat radiation surface for the heated material W on the walking beam 2. In this invention, the term "breathable solid" refers to a solid made of a heat-resistant material such as metal or ceramic, and formed into a shape having air permeability such as a net shape, a honeycomb shape, a fiber shape, or a porous shape, and having an appropriate thickness. In the example, a plate-shaped material with a thickness of about 10 mm made by laminating 8 layers of stainless wire mesh (wire diameter 0.6 mm, 16 meshes) is used. This air-permeable solid is considered to be equivalent to a large number of small spheres or small-diameter wires, so its effective surface area is extremely large, and when gas is passed through this air-permeable solid, the convective heat transfer coefficient is extremely large. It can be said. 14 is a flue.

In order to heat the material to be heated using the apparatus configured as described above, the material to be heated W is transported in the direction of the arrow X by the walking beam 2 while being burned by the burner 4, and the material to be heated is heated in the heating chamber 3. At the same time, the high temperature fan 9 is operated. The heated material is mainly exposed to the high temperature (1000°C) generated by burner 4.
It is heated by radiant heat transfer from the furnace wall heated by the combustion gas (~1200°C) and convective heat transfer with the combustion gas. Due to the operation of the high temperature fan 9, the combustion gas in the heating chamber 3 passes through the partition 11 and enters the opening 12.
and is sucked into the high-temperature fan 9 as exhaust gas.
At this time, the partition 11 is heated to around 1000°C by convective heat transfer by the passing combustion gas, so the partition 11 radiates a large amount of radiant heat from its heat radiation surface 13, and the heated material W passing near the partition 11 radiates a large amount of radiant heat. radiant heating. The combustion gas whose temperature has decreased to approximately 800°C by passing through the partition 11 is forced into the plenum chamber 7 via the exhaust gas pipe 8 and the high temperature fan 9, and is injected at high speed from the jet hole 6 and passes through the preheating chamber 5. Jet preheats the material to be heated. The exhaust gas after preheating is
The temperature is lowered to 400 to 600°C, and the heated material flows to the charging side, and is discharged to the outside through the flue 14 and a recuperator (not shown).

In this way, a part of the sensible heat possessed by the combustion gas flowing out of the heating chamber 3 is converted into radiant heat by the partition 11 made of a breathable solid and is directly and effectively used for heating the material to be heated. Thermal efficiency in the area is improved. Furthermore, since the temperature of high-temperature combustion gas drops by about 200 to 300°C when it passes through the partition 11, even in the case of a high-temperature furnace where the temperature of the combustion gas in the heating chamber 3 exceeds the allowable suction temperature of the high-temperature fan 9 by about 200 to 300°C, By installing 11, exhaust gas can be pumped without any trouble using the high temperature fan, and jet preheating in the preheating chamber 5 is made possible.

In the above embodiment, a high-temperature fan was used as the exhaust gas pumping device, but an ejector may be used instead. In this case, the temperature of the combustion gas decreases as it passes through the partition 11 made of breathable solid, so the substantial amount of gas entrained in the ejector increases, and the jet velocity increases toward the heated material passing through the preheating chamber 5, causing the jet to flow. Preheating efficiency is improved.

In addition to the embodiments described above, the present invention can be applied to various types of heating furnaces, heat treatment furnaces, etc. that use high-temperature combustion gas or high-temperature atmospheric gas.

As explained above, according to the present invention, the ventilation inside the heating chamber is improved by using an extremely simple structure in which a partition made of an air-permeable solid is provided to cover the opening of the exhaust gas pipe leading to the preheating chamber into the heating chamber. Thermal efficiency in the heating chamber can be improved by adding radiant heat transfer to the heated material in the partition made of a solid material, and together with the improvement in thermal efficiency in the preheating chamber due to jet preheating, the thermal efficiency of the furnace is improved, resulting in energy savings. can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a preheating device for a heated material showing an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along the line AA in FIG. 3...Heating chamber, 5...Preheating chamber, 6...Blowout hole,
7...Plenum chamber, 8...Exhaust gas pipe, 9
... High temperature fan, 11 ... Partition, 12 ... Opening, 13 ... Heat radiation surface.

Claims (1)

[Claims] 1. A preheating chamber equipped with an ejection hole facing the material to be heated is provided on the heating material charging side of the heating chamber of a heating furnace or heat treatment furnace, and a preheating chamber is provided in the exhaust gas pipe that communicates the heating chamber and the ejection hole. 1. A preheating device for a heated material, comprising: an exhaust gas pressure feeding device; and a partition made of an air-permeable solid that covers an opening in the heating chamber of the exhaust gas pipe and faces the heated material.