JP2003172582A - Drying furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drying furnace which reduces the newly supplied air for combustion by directly mixing a waste gas with the air for combustion of a burner of the drying furnace, and improves the efficiency in combustion of the burner by the preheat of the waste gas. <P>SOLUTION: A circulating channel 9 is formed for directly recirculating a part of the waste gas from a gas flue 6 to an air supply passage 5. Further a mixer 11 for adjusting a mixing ratio of the air for combustion and the waste gas is mounted on a meeting part of the air supply passage 5 and the circulating channel 9. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to
The present invention relates to a drying furnace for generating combustion gas with a burner and drying an object to be dried.

[0002]

2. Description of the Related Art Generally, a drying oven is used in various drying processes such as a dust processing process for drying solid waste to form a solid fuel, a paint drying process for an object to be coated, and a drying process after washing an article. ing. As shown in FIG. 3, a conventional drying furnace has a furnace body 2 into which a material to be dried is introduced, a burner 3 provided in the furnace body 2, and a fuel supply path 4 for supplying fuel to the burner 3. An air supply path 5 for supplying air to the burner 3 and a flue 6 for discharging the exhaust gas generated in the furnace body 2 to the outside.

The air supply passage 5 is provided with a pushing fan 7 for making the air flow direction constant, and the flue 6 is provided with a deodorizing device 8 for deodorizing exhaust gas. Although not shown, the deodorizing device 8 includes a deodorizing furnace that thermally decomposes or burns odorous components in the exhaust gas.

In the drying furnace as described above, the burner 3 is burned by supplying the fuel to the burner 3 through the fuel supply passage 4 and at the same time supplying the dilution air through the air supply passage 5. Hot air is generated by the generated combustion gas, and the hot air is blown onto the material to be dried to dry the material to be dried. The exhaust gas generated in the furnace body 2 is guided to the flue 6, introduced into the deodorizing device 8 to be deodorized, and then released to the atmosphere.

The temperature of the exhaust gas in the flue 6 is about 150 to 200 ° C., and the oxygen concentration in the exhaust gas is about 16 to 17%.

[0006]

In the conventional drying furnace as described above, in order to effectively use the energy of the exhaust gas, for example, a regenerated air preheater (not shown) is installed in the flue 6 to exhaust the exhaust heat. There is a method of collecting and preheating the air supplied into the furnace body 2. However, when the regenerated air preheater is adopted, the exhaust gas temperature is about 150 to 200 ° C. Therefore, for example, when a large amount of water is attached to the material to be dried, white smoke is caused by the excess water. Occurs, and also
In the solid waste fuel molding process, there is a problem that sulfuric acid dew point corrosion or the like is caused in the regenerated air preheater due to the generation of sulfur content. Further, since the amount of passing gas in the regeneration air preheater is enormous, there is a problem that the entire apparatus becomes large.

The present invention has been made in view of the above circumstances. By directly mixing the exhaust gas with the combustion air of the burner of the drying furnace, the combustion air to be newly supplied is reduced and the exhaust gas is preheated. Thus, it is an object of the present invention to provide a drying furnace capable of improving the efficiency of burner combustion.

[0008]

In order to solve the above-mentioned problems, the invention described in claim 1 is a furnace body, and a burner for generating combustion gas for drying an object to be dried in the furnace body, A drying furnace having an air supply path for supplying combustion air to the burner and a flue for discharging exhaust gas generated in the furnace body to the outside, wherein a part of the exhaust gas is supplied from the flue to the air. It is characterized by having a circulation flow path for direct recirculation to the passage. According to this drying furnace, a part of the exhaust gas flows through the circulation flow path and is recirculated, and is reused for combustion in the furnace body.

According to a second aspect of the present invention, a mixer for adjusting the mixing ratio of the combustion air and the exhaust gas is provided at the confluence of the air supply passage and the circulation passage. According to this drying furnace, the mixing ratio of the newly supplied combustion air and the exhaust gas in the mixed air supplied to the burner is adjusted by the mixer.

According to a third aspect of the present invention, the mixer is
It is characterized by having an automatic control mechanism for controlling the mixing ratio of the combustion air and the exhaust gas. According to this drying furnace, the mixing ratio of the newly supplied combustion air and the exhaust gas in the mixed air supplied to the burner is automatically adjusted by the mixer.

According to a fourth aspect of the present invention, the automatic control mechanism has a sensor for measuring the oxygen concentration in the exhaust gas. According to this drying furnace, the mixing ratio of the newly supplied combustion air and the exhaust gas in the mixed air supplied to the burner is automatically adjusted by the mixer by the sensor measuring the oxygen concentration in the exhaust gas. To be done.

[0012]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described below with reference to FIG. In FIG. 1, the same components as those in FIG. 3 are designated by the same reference numerals.

The drying furnace 1 is a furnace body 2 into which a material to be dried is introduced.
A burner 3 provided in the furnace body 2, a fuel supply path 4 for supplying fuel to the burner 3, an air supply path 5 for supplying air to the burner 3, and an exhaust gas generated in the furnace body 2. Is provided with a flue 6 for discharging The air supply path 5 is provided with a pushing fan 7 that makes the air flow direction constant, and the flue 6 is provided with a deodorizing device 8 that deodorizes exhaust gas.

A feature of this embodiment is that a circulation passage 9 for directly recirculating a part of exhaust gas from the flue 6 to the air supply passage 5 is provided. Further, an exhaust gas recirculation fan 10 that makes the flow direction of the exhaust gas constant is provided in the circulation flow path 9, and further, at the confluence of the air supply path 5 and the circulation flow path 9, the combustion air and the exhaust gas are combined. A mixer 11 for adjusting the mixing ratio is provided.

As shown in FIG. 2, the mixer 11 is provided with an automatic control mechanism 100 for adjusting the mixing ratio of the combustion air and the exhaust gas in the mixed air supplied to the burner. The automatic control mechanism 100 includes a combustion air flow rate adjusting valve 12, an exhaust gas flow rate adjusting valve 13, and motors 14 and 15 attached to the flow rate adjusting valves 12 and 13, respectively.
And a controller 17 for measuring the oxygen concentration of the exhaust gas and a controller 17.

Next, the operation of the illustrated example will be described. The burner 3 is burned by supplying fuel to the burner 3 in the furnace body 2 through the fuel supply passage 4 and at the same time supplying dilution air through the air supply passage 5. Then, hot air is generated by the combustion gas generated by the combustion of the burner 3, and the hot air is blown onto the object to be dried to dry the object to be dried.

The exhaust gas generated in the furnace body 2 is guided to the flue 6 and branched in two directions. One of the exhaust gases is introduced into the deodorizing device 8 to be deodorized and then released to the atmosphere. Further, the other exhaust gas is introduced into the circulation passage 9 by the exhaust gas recirculation fan 10 and circulated to the mixer 11.

The circulated exhaust gas is mixed with the combustion air supplied from the air supply passage 5 in the mixer 11. At that time, the sensor 16 measures the oxygen concentration in the exhaust gas, and the signal of the measurement result is input to the controller 17. Then, the controller 17 calculates optimum flow rate values of the exhaust gas and the combustion air based on the input signal, and outputs the optimum flow rate values to the motors 14 and 15. Each motor 14, 1
By adjusting the opening amount of each flow rate adjusting valve 12, 13 by driving 5, the mixing ratio of the exhaust gas in the mixed gas supplied to the burner 3 and the combustion air is automatically adjusted.

As described above, since a part of the exhaust gas having thermal energy and satisfying the combustion oxygen concentration is recirculated, and the exhaust gas is mixed with the combustion air to be reused as the burner combustion mixed gas, the efficiency is improved. Is planned. That is, the combustion air can be reduced, and further, the fuel required for preheating the air can be reduced. Further, since the amount of exhaust gas flowing into the atmosphere without being circulated is reduced, the deodorizing device 8 has a smaller capacity and a purification device (not shown) used for reducing volatile organic compounds in the exhaust gas. It is possible to reduce the storage capacity.

The present invention is not limited to the above-mentioned embodiments, and it goes without saying that various modifications can be made without departing from the gist of the present invention. For example, in the above-described embodiment, a part of the exhaust gas is recirculated to the furnace body 2 that has generated the exhaust gas, but when a plurality of furnace bodies 2 are used in the drying process or a gas turbine (not shown) is used. If you do
It is also possible to supply the exhaust gas generated from the furnace body 2 or the gas turbine for combustion of another furnace body 2. Also,
The oxygen concentration measuring sensor 16 in the exhaust gas used as an input of the automatic control mechanism of the mixer 11 is
It does not limit the installation location. For example, although the sensor 16 is installed in the mixer 11 in the above-described embodiment, it is not in the mixer 11 but in the circulation channel 9 or
Even if the sensor 16 is installed anywhere in the flue 6,
Operations and effects similar to those of the embodiment are achieved.

[0021]

As described above, according to the invention described in claim 1, since a part of the exhaust gas flows through the circulation flow path and is recirculated, it is reused for combustion in the furnace body. Combustion air can be reduced, and fuel required for air preheating can be reduced. Further, it becomes possible to reduce the emission amount of exhaust gas.

According to the invention described in claim 2, since the mixing ratio of the combustion air and the exhaust gas in the mixed air supplied to the burner is adjusted by the mixer, the oxygen concentration of the mixed air is always burned. It is possible to maintain the optimum value for.

According to the third aspect of the invention, since the mixing ratio of the combustion air and the exhaust gas in the mixed air supplied to the burner is automatically adjusted by the mixer, the oxygen concentration of the mixed air can be adjusted. It is possible to automatically maintain the optimum value for combustion at all times.

According to the invention described in claim 4, the mixing ratio of the combustion air in the mixed air supplied to the burner and the exhaust gas is automatically measured by the mixer by the sensor measuring the oxygen concentration in the exhaust gas. Since it is adjusted by, the oxygen concentration of the mixed air can always be automatically maintained at the optimum value for combustion.

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment of a drying furnace of the present invention.

FIG. 2 is a schematic view showing an embodiment of a mixer of the present invention.

FIG. 3 is a schematic view showing a conventional drying oven.

[Explanation of symbols]

1 drying oven 2 furnace body 5 Air supply path 6 flue 9 circulation channels 11 Mixer 16 sensors 100 Automatic control mechanism

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Fumihiko Tamamushi             3-2-16 Toyosu, Koto-ku, Tokyo Ishikawajima             Harima Heavy Industries Tokyo Engineering Co., Ltd.             In the center (72) Inventor Yuko Yoshida             3-2-16 Toyosu, Koto-ku, Tokyo Ishikawajima             Harima Heavy Industries Tokyo Engineering Co., Ltd.             In the center F term (reference) 3L113 AC04 AC61 AC87 BA39 CA12                       CB23 DA01

Claims (4)

[Claims] 1. A furnace body, a burner for generating combustion gas for drying an object to be dried in the furnace body, an air supply path for supplying combustion air to the burner, and an exhaust gas generated in the furnace body. A drying furnace having a flue for discharging the gas to the outside, the drying furnace having a circulation flow path for directly recirculating a part of the exhaust gas from the flue to the air supply path. 2. The drying furnace according to claim 1, wherein a mixer for adjusting a mixing ratio of the combustion air and the exhaust gas is provided at a confluence portion of the air supply passage and the circulation passage. 3. The drying furnace according to claim 2, wherein the mixer has an automatic control mechanism for controlling a mixing ratio of the combustion air and the exhaust gas. 4. The drying furnace according to claim 3, wherein the automatic control mechanism has a sensor for measuring the oxygen concentration in the exhaust gas.