JPS5818085A - Preheater for material to be heated - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

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, radiation is used as it is, which has 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.

This invention is based on the above-mentioned points, and aims to provide a preheating device for a heated material that has excellent heating characteristics for the heated material in a furnace and can achieve 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 type heating furnace, and 2 is a walking beam, which moves in a rectangular or elliptical shape by a known mechanism (not shown). 8 is a heating chamber of the heating furnace, and 4 is a burner.

Reference numeral 5 denotes a preheating chamber with an extended furnace length on the side of the heating chamber 3 where the material to be heated is charged, and a plenum having a large number of jet holes 6 facing the material to be heated on the walking beam 2 is installed in the ceiling of the preheating chamber 5. Chamber 7 is permanently installed. Reference numeral 8 denotes an exhaust gas pipe line that communicates the heating chamber 8 and the plenum chamber 7, and a high-temperature tube 7 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, and an opening 1 of the exhaust gas pipe 8 to the heating chamber 3.
2, and 18 is a heat radiation surface facing the heated material W on the walking beam 2. In this invention, the term "breathable solid" refers to a solid made of 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 perforated shape, or a porous shape, and having an appropriate thickness. In the example, stainless steel wire mesh (wire diameter Q, 511
11.16 mesh) is used, which is laminated in 8 layers to form a plate with a thickness of about 10 pieces. 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 number of convective heat transfers is extremely large. It can be said that it is large. 1 and 4 are flues.

In order to heat the material to be heated using the apparatus configured as described above, the material to be heated W is conveyed in the direction of the arrow X by the walking beam 2 while being burned by the burner 4 to heat the material to be heated in the heating chamber 8. At the same time, the high temperature fan 9 is operated. The material to be heated is mainly heated by radiant heat transfer from the furnace wall heated by high temperature (1000 to 1200° C.) combustion gas generated by the burner 4 and convective heat transfer with the combustion gas. When the high-temperature fan 9 is operated, the combustion gas in the heating chamber 3 passes through the partition 11 and is drawn into the high-temperature chamber 9 through the opening 12 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 one heat radiation surface and the heated material W passing near it is heated. 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 7 9, and is injected at high speed from the jet hole 6 to the preheating chamber 5.
A jet stream heats the heated material passing through the inside. After preheating, the exhaust gas has a temperature lowered to 400 to 600°C, flows to the heating material charging side, and is discharged to the outside through the flue 14 and a recuperator (not shown).

A part of the sensible heat of 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 heated material. Thermal efficiency in the area is improved. Furthermore, the temperature of high-temperature combustion gas decreases by about 200 to 800 degrees Celsius when it passes through the partition 11, so even in the case of a high-temperature furnace where the temperature of the combustion gas in the heating chamber 8 exceeds the allowable suction temperature of the high-temperature fan 9 by about 200 to 800 degrees 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 is 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 a breathable solid, so the substantial amount of gas entrained in the ejector increases, and the velocity of the jet toward the heated material passing through the preheating chamber 5 increases, 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, a very simple structure is provided in which a partition made of a breathable solid is provided to cover the opening of the exhaust gas pipe leading to the heating chamber into the heating chamber. Thermal efficiency in the heating chamber can be improved by adding radiant heat transfer to the heated material through partitions made of It can be achieved.

[Brief explanation of the drawing]

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

Claims (1)

[Claims] 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 a heat treatment furnace, and exhaust gas is introduced into an exhaust gas pipe line that communicates the heating chamber and the ejection hole. A preheating device for a heated material, characterized in that a pressure feeding device is provided, and a partition made of an air permeable solid that covers the opening in the heating chamber of the exhaust gas pipe and faces the heated material.