JP3321947B2 - Tunnel type continuous firing furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tunnel type continuous firing furnace suitable for firing ceramics such as sanitary ware, tiles, etc., and stabilizes the atmosphere in the furnace when a change in firing load occurs. The present invention relates to a tunnel type continuous firing furnace that can automatically cope with such problems.

[0002]

2. Description of the Related Art A conventional tunnel type continuous firing furnace is composed of three parts, that is, a pre-tropical zone, a firing zone, and a cooling zone, which are arranged in order from an inlet side to an outlet side.

[0003] A firing burner is arranged in the firing zone, and the combustion gas generated in the firing zone is guided to the pre-tropical side by an exhaust fan provided outside the furnace at a position corresponding to the pre-tropical zone. After that, it is discharged outside the furnace.

Further, cooling air is blown into the cooling zone by a quenching fan provided outside the furnace to cool the fired product fired in the firing zone.

On the other hand, an outlet fan for blowing air toward the inlet side in the furnace is provided at the outlet of the firing furnace.

Further, a residual heat recovery fan is disposed in the cooling zone, and the fan is generated when the cooling air blown into the cooling zone comes into contact with the fired product to exchange heat and be heated. Air after heating can be collected.

In such a tunnel type continuous firing furnace, the opening degree of the exhaust fan, the quenching fan, the residual heat recovery fan, and the dampers provided on the suction side and the discharge side of each fan is controlled. , Pre-tropical and cooling zone heat curves. On the other hand, the heat curve of the firing zone is controlled by a firing burner.

[0008]

In the operation of the tunnel type continuous firing furnace described above, if a change in the firing time or a change in the firing load (such as the size of the product to be fired or an increase or decrease in the quantity) occurs, the firing of the firing zone is performed. The combustion amount of the burner fluctuates, the amount of generated combustion gas increases and decreases, the flow and pressure of the combustion gas in the furnace change, and a predetermined heat curve cannot be maintained, and a defect occurs in the fired product.

Therefore, conventionally, in order to maintain a predetermined heat curve, a furnace operator adjusts the air volume by operating dampers such as the exhaust fan, the cooling fan, and the residual heat recovery fan based on experience. There are the following problems.

(1) The timing of the adjustment is adjusted after the furnace operator confirms the fluctuation, and the adjustment cannot be performed in real time.

(2) When determining the amount to be adjusted, the amount of adjustment differs for each operator, and the firing quality is not stable.

(3) The amount to be adjusted is repeated several times while checking the result after adjustment, and it takes time to adjust to find an appropriate value.

An object of the present invention is to provide a tunnel type continuous firing furnace which can be set to a predetermined firing condition with high accuracy and without requiring the skill of an operator even when the firing time is changed or the firing load is changed. Is to provide.

[0014]

The present invention comprises three parts, a pre-tropical zone, a sintering zone, and a cooling zone. The combustion gas generated in the sintering zone is guided to the pre-tropical zone to be discharged outside the furnace. A tunnel-type continuous firing furnace comprising: an exhaust fan that discharges air; a quenching fan that blows air for rapidly cooling a fired product in the cooling zone; A pushing fan for pushing air inside the furnace in the cooling zone toward the furnace inlet, a discharge air amount adjusting means for adjusting the amount of air discharged from the pushing fan, and oxygen in the furnace in a buffer zone near a boundary between the firing zone and the cooling zone. The present invention relates to a tunnel type continuous firing furnace characterized by comprising oxygen concentration detecting means for detecting the concentration, and controlling the discharge air volume adjusting means by a signal from the oxygen concentration detecting means.

The present invention further comprises pressure detecting means for detecting the pressure inside the furnace in the pre-tropical zone, and exhaust air volume adjusting means for adjusting the amount of exhaust air from the exhaust fan, and a signal from the pressure detecting means. There are also structural features in controlling the discharge air volume adjusting means, and in sucking air in the furnace near the furnace outlet of the cooling zone with the pushing fan and discharging the air toward the firing zone side.

[0016]

The oxygen concentration detector provided in the buffer zone of the cooling zone detects and measures the oxygen concentration in that portion, so that the combustion gas flows from the firing zone to the cooling zone, and conversely, from the cooling zone to the firing zone. Of the air in the cooling zone is controlled, whereby the air pushed from the pushing fan toward the firing zone is controlled, and the pressure balance between the firing zone and the cooling zone is maintained.

[0017] Further, with respect to a sudden load fluctuation, the pressure fluctuation in the pre-tropical zone is detected by a pressure detector provided in the pre-tropical zone, together with the control of the air forced from the pushing fan toward the firing zone. By controlling the amount of exhaust from the exhaust fan, the balance in the furnace is maintained.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the embodiments shown in the accompanying drawings.

FIG. 1 shows a conceptual structure of a tunnel type continuous firing furnace (tunnel furnace) A for firing sanitary ware, and FIG.
Shows a heat curve (heat curve) in the tunnel type continuous firing furnace.

As shown in FIGS. 1 and 2, the tunnel-type continuous firing furnace A includes a pre-tropical zone 1, a firing zone 2, and a cooling zone 3 in order from the furnace inlet to the furnace outlet.

(Pre-tropical zone 1) First, the configuration of the pre-tropical zone 1 will be described. The pre-tropical zone 1 is provided with a flue (not shown) formed on both side walls and a lower portion of the furnace.

On the other hand, an exhaust fan 6 is disposed outside one side wall of the pre-tropical zone 1, and the exhaust fans 6 are attached to both sides of the pre-tropical zone 1 of the furnace at predetermined longitudinal intervals. The duct 9 communicates with the flue in the pre-tropical zone 1.

Therefore, the combustion gas generated in the sintering zone 2 by the operation of the exhaust fan 6 is drawn into the furnace inlet side or the pre-tropical zone 1 through the flue, and then discharged outside through the duct 9. be able to.

In FIG. 1, reference numeral 7 denotes a damper provided on the inlet side of the exhaust fan 6, and reference numeral 8 denotes a damper provided in the middle of each duct 9.

The pre-tropical zone 1 is provided with a pre-heat burner 41 for setting a heat curve in a region near the sintering zone 2.

Further, as shown in FIGS. 1 and 6, the pre-tropical zone 1 has, on one side wall thereof, a pressure detector for detecting a furnace pressure.
10 is attached, and the pressure detector 10 is connected to a pressure measuring device 11 arranged outside the furnace. On the other hand, the pressure measuring device 11
Is connected to a rotation speed control device (inverter) 31 of the exhaust fan 6, as shown in FIGS.

(Sintering Zone 2) Next, the configuration of the sintering zone 2 provided downstream of the pre-tropical zone 1 will be described.

As shown in FIG. 1, the sintering zone 2 has a plurality of sintering burners 12 mounted on both side walls thereof at intervals in the longitudinal direction. The unburned product can be fired by the high-temperature combustion gas generated by the operation of the firing burner 12 (see FIG. 2).

(Cooling Zone 3) Next, the structure of the cooling zone 3 provided continuously on the downstream side of the firing zone 2 will be described.

As shown in FIGS. 1 and 2, the cooling zone 3
It comprises a quenching section 4 on the upstream side and a slow cooling section 5 on the downstream side.

Here, the quenching section 4 is an area for rapidly cooling the fired product fired in the firing zone 2, and includes a quenching fan.
15 is arranged outside the furnace, and low-temperature room temperature air can be blown into the quenching section 4 through a duct 15a in which a damper 16 is mounted halfway.

On the other hand, the slow cooling section 5 is an area where the fired product cooled to a predetermined temperature in the rapid cooling section 4 is gradually cooled to room temperature.

As shown in FIG. 1, an oxygen concentration detector 13 for detecting the oxygen concentration in the furnace in the same region is arranged in a buffer zone 42 on the sintering zone side of the quenching section 4. .
The arrangement position is set to the buffer zone 42 because the buffer zone 42 is a region which is not affected by the air blown from the firing burner 12 and the quenching fan 15 of the firing zone 2.

The oxygen concentration detector 13 is, as shown in FIG.
The oxygen concentration detector 13 is attached to the furnace side wall such that its tip faces the inside of the furnace. On the other hand, as shown in FIG. 5 and FIG. (Oxygen analyzer) 14, and the oxygen concentration measuring device 14 is a rotational speed control device of the push-in fan 21 via an oxygen concentration controller 32.
(Inverter) 30 connected.

As shown in FIG. 1, the cooling zone 3 is provided with an outlet blower fan 25 at the furnace outlet downstream of the slow cooling unit 5. The air can be sucked and blown into the slow cooling unit 5.

Further, the cooling zone 3 is provided with a residual heat recovery fan 17 outside the furnace, and the fan 17 is provided with the air blown into the slow cooling section 5 by the outlet blowing fan 25 described above, and The outside air entering the slow cooling section 5 from the furnace outlet can be sucked through the plurality of branch intake ducts 20 and the collective intake duct 18a and discharged outside the furnace.

Reference numeral 19 denotes a damper provided in each of the branch intake ducts 20, and reference numeral 18 denotes a damper provided in the collective intake duct 18a.

As described above, in the cooling zone 3, the sucked low-temperature air comes into contact with the fired product, and the fired product is cooled at a predetermined temperature curve.

Further, in the cooling zone 3, a pushing fan 21 is arranged on a furnace side wall near a furnace outlet thereof.
The suction port communicates with the furnace outlet side space of the slow cooling section 5 by the suction duct 21a, and the discharge port communicates with the space on the upstream side of the furnace outlet side space by the discharge duct 21b.

The discharge opening of the discharge duct 21b is directed toward the sintering zone 2, as shown in FIGS.

As shown in FIGS. 1, 3 and 4,
Each of the suction duct 21a and the discharge duct 21b is provided with a damper 23 for adjusting the amount of furnace air suction and a damper 22 for adjusting the amount of furnace air discharge.

With this configuration, the air (about 100 to 200 ° C.) in the furnace in a relatively low temperature region of the slow cooling section 5 of the cooling zone 3 is drawn by the suction duct 21 a by the operation of the pushing fan 21.
Then, the sucked air can be blown toward the upstream portion (sintering zone side) in the furnace via the discharge duct 21b, that is, can be pushed in.

In this case, as shown in FIG.
On the suction side 21, a part of room air is sucked together through a part room air suction duct 24 a provided with a damper 24.

(Operation) Next, the operation of the tunnel type continuous firing furnace having the above configuration will be described.

The heat curve in FIG. 2 shows a heat curve in a preset steady state, in which the pressures in the sintering zone 2 and the cooling zone 3 are balanced and the combustion gas does not flow into the cooling zone 3. Has become. In this state, firing zone 2
The oxygen concentration in the furnace of the buffer section 42 of the cooling zone 3 is a set value (for example, 15 ± 1%).

When the calcination is performed for a shorter time than the predetermined time, the amount of combustion from the calcination burner 12 is required to increase the calcination weight, the generated combustion gas increases, and the pressure in the furnace of the calcination zone 2 decreases. High, and some of the combustion gas
And the oxygen concentration in the quenching section 4 decreases.

As shown in FIGS. 5 and 7, a signal from the oxygen concentration detector 13 is received by the oxygen concentration measuring device 14, and when the oxygen concentration falls below the set value, the signal from the oxygen concentration measuring device 14 is pushed. The rotation speed control device (inverter) 30 of the fan 21 receives the rotation speed of the push-in fan 21 and raises the pressure in the furnace of the cooling zone 3 to prevent the combustion gas from flowing into the cooling zone 3. I do. As a result, the set heat curve can be maintained.

When the weight of the fired product increases rapidly, the amount of combustion from the combustion burner 12 increases abnormally, the furnace pressure in the firing zone 2 increases, and the temperature of the firing zone 2 increases. Heat curve cannot be maintained. Then, a part of the combustion gas blows out from the furnace entrance of the pre-tropical zone 1.

In this state, the pressure in the furnace of the pre-tropical zone 1 rises above a set value, and the pressure rise is detected by the pressure detector 10. In response to this detection signal, the pressure measuring device 11 measures the pressure, and controls the rotation speed control device (inverter) 31 as the exhaust air volume adjusting means of the exhaust fan 6 based on the signal,
The rotation speed of the exhaust fan 6 is increased, and the pressure in the furnace of the pre-tropical zone 1 is controlled to a set value. As a result, the set heat curve can be maintained.

On the other hand, if the calcination is performed for a longer time than the predetermined time, the calcination burner 12
, The pressure in the furnace in the combustion zone 2 decreases, air at a low temperature from the cooling zone 3 flows into the firing zone 2, the oxygen concentration in the quenching section 4 increases, and As the temperature decreases, a predetermined heat curve cannot be maintained, defects such as insufficient baking of the product occur, more fuel is used than necessary to maintain the temperature, and heat loss increases.

In this case, the oxygen concentration detector 13 detects an increase in the oxygen concentration in the furnace of the quenching part 4 of the cooling zone 3 and
The rotation speed of 21 is reduced to reduce the pressure in the furnace of the cooling zone 3 to prevent the flow of low-temperature air from the cooling zone 3 into the sintering zone 2.

When the weight of the calcined product suddenly decreases from the steady state, the amount of combustion from the calcining burner 12 sharply decreases, and the exhaust fan 6 emits not only the combustion gas from the calcining zone 2 but also from the furnace inlet. Low temperature air is sucked in, and the heat curve of Pre-Tropical 1 cannot be maintained.

In this state, the rotation speed of the pushing fan 21 is controlled and the rotation speed of the exhaust fan 6 is controlled. That is, as shown in FIGS. 6 and 8, the pressure detector 10 detects a decrease in the pressure in the furnace of the pre-tropical zone 1 that is lower than a predetermined value. In response to the detection signal, the pressure is measured by the pressure measuring device 11, and the signal is used to control the rotation speed of the exhaust fan 6 (inverter) 3.
1 is controlled, the number of revolutions of the exhaust fan 6 is reduced, and the furnace pressure is controlled to a predetermined value.

In this embodiment, a rotation speed control device (inverter) for controlling the rotation speed of the push-in fan 21 is used as the means for adjusting the amount of air discharged from the push-in fan 21.
The rotation speed of the push-in fan 21 may be fixed, and the discharge-side damper 22 of the push-in fan 21 may be a control-type damper, and its opening may be adjusted to adjust the discharge air volume.

Similarly, in this embodiment, a rotation speed control device (inverter) for controlling the rotation speed of the exhaust fan 6 is used as the means for adjusting the amount of air discharged from the exhaust fan 6. The number of revolutions may be constant, and the intake-side damper 7 of the exhaust fan 6 may be a control-type damper, and its opening may be adjusted to adjust the amount of exhaust air.

The air sucked by the push-in fan 21 is not limited to the air inside the furnace of the cooling zone 3, but a separate device for heating the air may be provided to heat the room-temperature air and suck the heated air.

[0057]

As described above, according to the present invention,
In the tunnel type continuous firing furnace, a pushing fan for pushing the furnace air in the cooling zone toward the furnace entrance, a discharge air amount adjusting means for adjusting the amount of air discharged from the pushing fan, and the vicinity of the boundary between the firing zone and the cooling zone. Oxygen concentration detecting means for detecting the oxygen concentration in the furnace in the buffer zone is provided, and the discharge air volume adjusting means is controlled by a signal from the oxygen concentration detecting means.

In addition, the tunnel type continuous firing furnace further includes:
Pressure detection means for detecting the pressure in the furnace in the pre-tropics,
A discharge air amount adjusting means for adjusting the amount of air discharged from the exhaust fan is provided, and the exhaust air amount adjusting means is controlled by a signal of a pressure detecting means, or a forced air fan sucks air in the furnace near the furnace outlet of the cooling zone, Discharge is performed toward the firing zone.

Therefore, the present invention has the following effects.

The heat curve is automatically adjusted in real time in response to a change in the firing conditions such as a change in the firing time, a change in the firing load (a change in the size of the product to be fired, an increase or decrease in the quantity, etc.), and the furnace atmosphere is changed. Can be stabilized.

[0061] Irrespective of the change in the firing conditions, the firing can be performed under the optimum conditions, so that the occurrence of defects in firing of the product can be prevented, and the quality of the product is stabilized.

Since the firing conditions can be automatically controlled based on the oxygen concentration detection value and the pressure detection value, skill is not required to set the firing conditions as compared with a case where the firing is performed manually.

Since the pushing fan sucks air in the low temperature range of the cooling zone, the pushing fan is not required to have heat resistance and cost is reduced. Further, since the sucked low-temperature air is blown into the furnace again, there is an effect of cooling the fired product.

[Brief description of the drawings]

FIG. 1 is an overall plan view showing a conceptual configuration of a tunnel type continuous firing furnace according to the present invention.

FIG. 2 is a graph showing a change in furnace temperature in the tunnel type continuous firing furnace.

FIG. 3 is a plan view showing an installation state of a pushing fan.

FIG. 4 is a side view showing an installation state of a pushing fan.

FIG. 5 is a sectional view showing an installed state of an oxygen concentration measuring device.

FIG. 6 is a cross-sectional view showing an installation state of a pressure detector.

FIG. 7 is a push-in fan control block diagram based on oxygen concentration measurement.

FIG. 8 is an exhaust fan control block diagram based on pressure measurement.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pretropical zone 2 Firing zone 3 Cooling zone 6 Exhaust fan 15 Rapid cooling fan 17 Residual heat recovery fan 21 Push-in fan 42 Buffer zone

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-270884 (JP, A) JP-A-5-172465 (JP, A) JP-B-60-12553 (JP, B2) JP-B-1 13032 (JP, B2) (58) Field surveyed (Int. Cl. ⁷ , DB name) F27B 9/00-9/40

Claims (3)

(57) [Claims] 1. Pre-tropical zone (1), firing zone (2), cooling zone
(3), an exhaust fan (6) for guiding the combustion gas generated in the sintering zone (2) to the pre-tropical zone (1) and discharging the gas outside the furnace, and the cooling zone (3). ) A quenching fan (15) that blows air into the cooling zone (3) to rapidly cool the fired product
A tunnel type continuous firing furnace comprising a residual heat recovery fan (17) for recovering the blown air, a pushing fan (21) for pushing the furnace air in the cooling zone (3) toward the furnace inlet, Discharge air flow rate adjusting means for adjusting the discharge air flow rate from the pushing fan (21), and an oxygen concentration for detecting a furnace oxygen concentration in a buffer zone (42) near a boundary between the firing zone (2) and the cooling zone (3). A tunnel type continuous firing furnace, comprising: a detecting unit; and controlling the discharge air volume adjusting unit based on a signal from the oxygen concentration detecting unit. 2. A pressure detecting means for detecting a pressure in the furnace in the pre-tropical zone (1), and a discharge air amount adjusting means for adjusting an exhaust air amount from the exhaust fan (6). 2. The continuous firing furnace according to claim 1, wherein the control means controls the amount of discharged air. 3. The tunnel type as claimed in claim 1, wherein said pushing fan (21) sucks in-furnace air near the furnace outlet of the cooling zone (3) and discharges the air toward the firing zone. Continuous firing furnace.