JPS595830B2 - Atmosphere heating furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a radiant tube type atmosphere heating furnace.

In more detail, in a radiant tube type atmosphere heating furnace that uses No. A hydrocarbon gas as heating fuel, flammable in-furnace protective atmosphere waste gas is recovered and introduced into the heating burner, where it is re-burned. This article relates to improvements in atmosphere heating furnaces that utilize combustion heat as a heating source to save energy.

Conventional atmosphere heating furnaces often require electrical energy as a heating source, and they also use inert gas to protect the processed material from oxidation and decarburization, or depending on the processing purpose such as nitrocarburizing, carburizing, or brazing. An atmospheric gas containing flammable components such as H2 and CO is used.

Atmospheric gas containing these combustible components must be supplied into the furnace in an amount of 5 to 10 times the volume of the furnace per hour depending on the use of the material to be treated, and must be discharged from the furnace for safe operation. The waste gas is forced to burn at the exhaust port. For this reason, the amount of heat carried out by the heated atmospheric gas and the amount of heat lost through combustion at the gas outlet reach a considerable amount, resulting in an enormous amount of energy loss. By the way, instead of the above-mentioned electric furnace, a radiant tube type atmosphere heating furnace has been put into practical use, in which a combustion burner is installed in a cylinder to heat the workpiece using radiant heat from the cylinder surface. Also in the furnace, the above-mentioned atmospheric gas is combusted when it is discharged.

The present inventors have devised the present invention to improve the above-mentioned energy loss in an atmosphere heating furnace.In particular, the present inventors have discovered that atmospheric waste gas emitted by combustion in a radiant tube type furnace can be utilized. Therefore, the present invention has been made.
The object of the present invention is to provide a radiant tube type in which flammable furnace protective atmosphere waste gas is recovered and introduced into the heating burner of the radiant tube, where it is re-burned in the heating burner and the combustion heat is utilized as a heating source. We provide atmospheric heating furnaces.

Therefore, the purpose of the present invention is to re-combust waste gas and utilize it efficiently, heat the inside of the furnace with this combustion heat, and effectively utilize waste gas that was conventionally wastefully discharged and combusted.
This reduces fuel consumption by recovering and refining the fuel and supplying it to the furnace as a protective atmosphere gas.
To provide an atmosphere heating furnace that utilizes energy effectively and saves resources.

Next, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows a longitudinal sectional front view of the atmosphere heating furnace, and FIG. 2 shows a side view of the same.

The furnace 1 includes a furnace body 3 made of a refractory material surrounded by a frame 2, and a rail 5 is provided on a floor member 4 of the furnace body 3 for placing and transporting a workpiece w.

Recesses 6, 6 are provided on the left and right sides of the floor member 4, into which the U-shaped bent portions 7a of the radiant tubes 7, 7 face,
In the illustrated example, a plurality of radiant tubes 7, 7 are provided vertically in the front-rear direction so as to form pairs on the left and right sides of the furnace body 3. As is known, the radiant tubes 7, 7 are made of a cylindrical body made of refractory material or special refractory metal, which is bent into a U shape, and both ends 7b, 7c are connected to the furnace body 3 and the ceiling 3a, 2a of the frame 2. 7c is used as a discharge port. The other 7b is an inlet, and heating burners 8 are installed in this part, and the burners 8 are supplied with a hydrocarbon gas such as propane from a supply source via a pipe 9 and a control valve 10. Into the chamber S of the above-mentioned furnace 1, an inert gas for preventing oxidation and decarburization of the material to be treated, and an atmospheric gas according to the processing purpose such as nitrocarburizing, carburizing, and brazing are introduced, and the gas is H2 , containing combustible components such as CO.

Then, hydrocarbon gas is supplied to the burner 8 as a fuel gas, mixed with oxygen, burned in the burner 8, and the processed material W in the chamber S is transferred to the radiant tube 7...
It is heated by radiant heat to perform the desired treatment. By the way, as mentioned above, protective atmosphere gas is supplied into the chamber S in an amount of 5 to 10 times the furnace internal volume per hour depending on the purpose of processing the workpiece W, and therefore a gas introduction port (not shown) is provided. At the same time, the exhaust pipe 11 for exhaust gas after use is installed on the ceilings 3a, 2a.
The waste gas is discharged to the outside via the exhaust pipe 11. One end 11a of this discharge pipe 11 is connected to the chamber S.
The other end 11 is opened to the ceiling and led out to the outside of the ceiling.
b is bent in this direction to form the entrance portion 7b of the radiant tube 7.
The exhaust pipe 11 is connected to the burner 8, and the exhaust pipe 11 is connected to the burner 8, and the waste gas discharged through the exhaust pipe 11 is supplied to the burner 8. A valve 12 is provided in the middle of the pipe 11. Ta. A plurality of these discharge pipes 11 are provided, and each is connected to each radiant tube 7 as described above. Therefore, the waste gas is supplied to the burner 8 portion of the radiant tube 7 via the exhaust pipe 11, where it joins with the fuel gas and is mixed and combusted together. In this way, the waste gas becomes part of the fuel gas and is used for combustion, and the consumption of fuel gas is reduced and suppressed.Since the waste gas is high temperature, combustion is carried out effectively, and the fuel gas is improves combustion efficiency. In the illustrated example above, a type with a vertical radiant tube is shown, but it is of course possible to apply this type to a type installed horizontally inside the furnace, and if necessary, a pump for pumping out waste gas etc. can be attached. It is also possible to do so.

As is clear from the above, according to the present invention, combustible waste gas is used as part of the heating fuel for the radiant tube, so fuel consumption is suppressed and reduced, and combustion is performed efficiently, thereby eliminating waste. Waste gas that was previously emitted by combustion can be used effectively, saving energy and resources.
Moreover, it is sufficient to simply extend the waste gas piping to the burner, and the above can be carried out without making any special changes to the radiant tube type atmosphere heating furnace, resulting in tremendous practical effects.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a vertical side view of an atmosphere heating furnace, and FIG. 2 is a vertical front view thereof. In the drawing, 1 is a furnace, 7 is a radiant tube, 8 is a burner, and 11 is a waste gas discharge pipe.

Claims (1)

[Claims] 1. A radiant tube that uses hydrocarbon-based gas as a heating fuel faces a furnace to which flammable atmospheric gas is supplied, and the other end of a discharge pipe with one end open inside the furnace is connected to the inlet of the radiant tube. An atmosphere heating furnace characterized in that atmospheric gas within the furnace is supplied into a radiant tube as part of the fuel.