JPS5812513B2 - heating furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a natural convection type heating furnace which is incorporated into a part of a conveyor line and is used to dry, bake coat, etc. the articles being conveyed.

In this type of heating furnace, an appropriate heat source is selected in consideration of thermal efficiency, stability, uniformity, safety, etc.

A burner device that burns liquid or gaseous fuel and heats the furnace by directly introducing hot air from the combustion gas into the furnace has economic advantages such as high thermal calorie, simple equipment, and ease of use.

However, on the other hand, since heat is carried into the furnace by the combustion gas to heat the article, it is necessary to introduce a large amount of combustion gas into the furnace.

This results in the same amount of gas being exhausted from the furnace, which results in wasted fuel if it is not metabolized efficiently.

Particularly problematic is the handling of the entrances and exits for goods on the conveyor line.

For this reason, a recirculation method has been considered in which the exhausted hot gas is recovered and forcibly introduced into the furnace again.

However, the recirculation method requires the installation of a circulation blower, duct, or heat exchanger, which has the disadvantage of increasing the number of parts and complicating the structure.

In addition, when a recirculation type furnace is used as a heating furnace for baking paint, the concentration of thinner generated from the paint gradually increases due to recirculation, which has the negative effect of making the painted surface cloudy. There is a risk of

To prevent this, air must be replenished to reduce the concentration, and heat dissipation from the recirculation duct is also large, resulting in no particular improvement in thermal efficiency.

By the way, there are cases where it is necessary to set the furnace body to be long due to the relationship between the speed of the conveyor line and the required heating time.

Although it is possible to use a mountain-shaped furnace for such a furnace, the flow of exhaust gas becomes faster, creating turbulent flow within the furnace and causing uneven temperature distribution within the furnace, making stable heating difficult. become capable.

A somewhat stable heat distribution can be obtained by carefully arranging the burner device, but it cannot be uniformly controlled depending on the heating temperature (fuel).

In particular, there is a lot of gas congested in the central part, and as mentioned above, in the case of baking painting, there is a risk of an adverse effect on the painted surface or an explosion.

In view of the above-mentioned problems, the present invention provides a natural convection type heating furnace having a long furnace body that can obtain stable and uniform heat distribution.

An embodiment of the present invention will be described below.

FIG. 1 shows the principle of a heating furnace of direct fuel combustion type.

In the figure, reference numeral a indicates a so-called chevron-shaped furnace body of the heating furnace, and a burner device C is installed in the lower floor b of the furnace body a.

Both ends of the furnace body a are inclined downwardly toward the outside, and an article inlet f and an article outlet g are formed at both ends, and a conveyor line d extends from the article inlet f to the article outlet g of the furnace body a. Articles e are placed on the top wall of the furnace, and are carried into the furnace from the article entrance f by the conveyor line d.The articles e are suspended and supported by the conveyor line d, pass through the furnace, and reach the article outlet g.
While the article e passes through the furnace, it is heated or baked or painted.

The upper edges f' and g' of the article entrances and exit ports f and g are set at approximately the same height as the floor surface of the lower furnace floor part b, and a bowl-shaped article heating area is formed in the furnace. .

The hot air generated by combustion in burner device c rises due to natural convection and is guided to the top of the furnace.
The low-temperature gas whose temperature has been lowered by heat exchange with the transported article e descends and is pushed out from the upper edges of the article inlet f and outlet g.

Therefore, the gas that fills the furnace is high temperature, and a mechanism is adopted in which the low temperature gas is exhausted first.

Next, specific examples of the heating furnace of the present invention are shown in FIGS. 2 and 3.

In FIG. 2, reference numeral 1 denotes a furnace body of a so-called mountain-shaped furnace, which is shaped like a long tunnel, and both ends thereof are inclined diagonally downward, and an article inlet 2 and an article outlet 3 are opened.

Inside the furnace body 1, a conveyor line 4 which is introduced and led out from an article inlet 2 and an article outlet 3 is laid along the upper wall, and articles 5 on the conveyor line 4 pass through the inside of the furnace body 1.

The upper edges of the article inlet 2 and article outlet 3 are set at approximately the same height as the lower floor 6 in the furnace.

A pit 8 is recessed in the lower floor 6 of the furnace, and a burner device 7 of a predetermined length is installed at the inner bottom of the pit 8.

The burner device 7 is constructed by arranging a large number of horizontal nozzle bars 9, 9 at regular intervals in the vertical direction.

A large number of nozzles are arranged on the nozzle bars 9, 9, and a large number of nozzle groups are arranged in the burner device 7 over a predetermined length having a constant width.

A plurality of burner devices 7, with this burner device 7 as one unit,
7 are arranged at appropriate intervals in the length direction inside the furnace.

Reference numerals 10 and 10 indicate baffle plates that cover the burner devices 7 and 7.

Hoods 11 and 1 are provided above the article inlet 2 and article outlet 3.
2 and connect the exhaust pipes 13 and 14.

If necessary, install a fan in the exhaust stack 13, 14.

Next, an exhaust pipe 15, 15 is inserted into the furnace body 1 between each burner device 7, 7 at a position that does not interfere with the passage of the article 5, for example, along the furnace side wall, as shown in the figure, and an exhaust port at the lower end thereof is inserted. 1
5', 15% upper edge 2' of the article inlet 2, article outlet 3,
It opens at the same height as 3'.

A fan is provided in the exhaust pipe 15.15 as required.

The exhaust pipe is connected to both conveyor lines 4 and 4, as shown by the dotted line in the figure.
4, or may be opened directly into the side wall of the furnace body 1.

In addition, the installation of the exhaust pipe 15.15 is performed at one of the burner devices 7,
-Multiple sets are assembled and installed between the burner devices of each set.

Even in a furnace body in which one side of the furnace body 1 is closed, the conveyor line makes a U-turn, and there is only one article entrance/exit, a similar configuration can be made by opening an exhaust port at the closed end.

The structure is constructed as described above, and the operation is as follows.

By driving the conveyor line 4, the articles 5 pass through the furnace from the article inlet 2 to the article outlet 3 one after another.

The burner devices 7, 7 are ignited all at once, and the furnace is filled with hot air as the fuel burns.

The hot air from each burner device 7, 7 is discharged from the article inlet 2, article outlet 3 and each exhaust stack 15, 15, with the hotter gas rising to the top and the cooler gas falling, due to convection phenomena.

That is, a heating furnace is constructed in which a burner device 7 is arranged in the center for each section of the furnace body 1 which is sandwiched between a material inlet 2, an article outlet 3, and an exhaust pipe 15, and these continuously form a long furnace body. form.

Therefore, the heat distribution is uniform and stable in each section as described above, and the heat distribution is uniform and stable as a whole.

In this way, the heating furnace of the present invention has a plurality of burner devices appropriately arranged, one to a plurality of burner devices being sandwiched between the article entrance,
Since the article outlet and the exhaust port are provided, a heating furnace that can accommodate a long conveyor line can be configured, and a long direct combustion type furnace body can be put to practical use.

Therefore, the speed and heating time of the conveyor line can be adjusted to any requirements, and it is easy to combine baking painting, draining and drying processes, etc. with other processes and incorporate them into the line.

By appropriately selecting the capacity and length of the burner device and appropriately limiting the interval between exhaust ports, the temperature distribution throughout the furnace can be maintained at a uniform high temperature, and the heating temperature conditions for the article can be adjusted to the required values. can.

The gas in the furnace is cooled by natural convection and is discharged from the article inlet, article outlet, and exhaust port, so it is constantly metabolized and there is no accumulation of gas. It also prevents negative effects on the paint and the risk of explosion.

Therefore, this furnace is thermally efficient and saves fuel.
It is a unique heating furnace that is easy to use, has low equipment costs, is extremely economical, and has excellent functionality.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing the principle of a heating furnace of direct fuel combustion type, Fig. 2 is a partially cutaway vertical side view showing an embodiment of the heating furnace of the present invention, and Fig. 3 is a central part of Fig. 2. FIG. 2 is a cross-sectional view showing a cut state. 1... Furnace body, 2... Article inlet, 3...
... Goods exit, 4 ... Conveyor line, 5
. . . Goods, 7 . . . Burner device, 13.
14...Exhaust pipe, 15...Exhaust pipe.

Claims (1)

[Claims] 1. In a natural convection type heating furnace equipped with a conveyor line for supporting articles to be conveyed to a nearly sealed furnace body having an article entrance/exit, the furnace body is configured to have a furnace structure that can accommodate a long conveyor line, and the furnace body has a furnace structure that can accommodate a long conveyor line. A plurality of burner devices are arranged at intervals on the lower floor of the furnace body along the longitudinal direction of the body, and the upper edge of the article entrance is set at approximately the same height as the floor surface of the lower furnace floor, The heating apparatus is characterized in that the burner apparatuses are arranged in sets of one or more burner apparatuses, and an exhaust port is provided in the furnace body between the burner apparatuses of each set and opens at a position approximately at the same height as the upper edge of the article entrance/exit. Furnace.