JP2013165685A - Tunnel type oven - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve combustion efficiency of a gas burner, to stabilize combustion and to make combustion temperature characteristics of a material to be burned at an initial stage of combustion suitable for the kind of the material to be burned in a tunnel type oven.SOLUTION: A tunnel type oven includes a plurality of convection heaters having suction ports arranged at the outside of a combustion furnace, suction pipes that make the suction ports communicate with a combustion room and take air outside the furnace in the combustion room, air jetting tubes that are connected to the suction pipes and have small holes for jetting air outside the furnace toward the material to be burned, pressure detection parts arranged on the suction pipes and pressure blowers for regulating pressure in the suction pipes at the entrance zone of the combustion room. The tunnel type oven further has a convection heater control part equipped with a memory part of a pressure value in a standard suction pipe for memorizing the pressure value in the standard suction pipe fit for the combustion condition of the material to be burned and a pressure blower control part for controlling the actuation of the pressure blower based on pressure values detected by the pressure detection parts and the memorized pressure value in the standard suction pipe.

Description

  The present invention relates to a tunnel oven for baking a baking object such as bread dough and confectionery dough.

  Tunnel-type ovens are used when baking objects such as bread dough and confectionery dough on a baking sheet and baking the baking sheet while conveying the baking sheet with the conveyor on a conveyor. ing. The tunnel oven has a firing furnace and a firing chamber formed in the firing furnace, and the temperature of the atmosphere in the firing chamber (firing temperature) is adjusted by controlling a heating device such as a burner provided in the firing chamber. Is done.

And since baking conditions differ with bread | pans or confectionery, it is necessary to bake on the temperature conditions corresponding to bread dough and confectionery dough.
Therefore, in Japanese Patent Publication No. 8-22201 (“Temperature Control Device for Tunnel Oven”: Patent Document 1), the inside of the tunnel oven is divided into a plurality of zones and sections, and a temperature detecting means is provided for each of these zones or sections. The control unit is arranged to store the optimum temperature of each zone for each product in the storage unit, and to control the temperature for each zone in the input unit, and performs control so that the optimum temperature is obtained for each zone. Are disclosed.

  Moreover, in patent 4680175 ("baking method of baked confectionery": Patent Document 2), a plurality of heat sources are provided above and below the operation kiln, and a duct as an intake means for taking in air above the operation kiln, Air release tube as an air release means for releasing air taken in from the intake means downward in the operation kiln, a blower pipe for sending air taken from the intake means to the air release means, and air taken in from the intake means Convection apparatus provided with air moving means in the air blowing pipe that moves the air through the air blowing pipe so as to be discharged from the air discharge port of the air discharging means. While heated by the heat sources above and below the operation kiln, the convection device continuously or intermittently applies air taken from the intake means to the surface of the confectionery dough, and the side of the baked confectionery dough How the temperature of the vicinity fired adjusted so as not to be lower relatively than near the top is disclosed.

  Furthermore, the applicant of the present application also focused on the bottom surface of the food mold as a baking means for baking the dough put into the food mold in Japanese Patent No. 4198573 ("Bread bread manufacturing apparatus and bread bread manufacturing method: Patent Document 3"). A bottom heating means for heating and a side heating means for heating the side surface of the food mold after heating the bottom surface of the food mold intensively, and the bottom surface heating means and the side surface heating means blow out hot air. In the baking process of bread, the degree of heating of the bottom and side surfaces of the food mold is changed at an arbitrary timing, for example, from the start of the baking process. During a certain period, the bottom surface of the food mold is heated relatively stronger than the other periods, and after the certain period is over, the side surface of the food mold is moved more than the other periods by using the side surface heating means. relative It has proposed what was to be able to strongly heated to.

Japanese Patent Publication No. 8-22201 Patent No. 4680175 Japanese Patent No. 4,198,573

However, in the invention of Patent Document 1, temperature control is performed by operating or stopping the burner, and precise temperature control is difficult. In addition, the initial stage of firing of an object to be fired carried into the firing chamber, that is, firing. In the entrance zone of the chamber, the surface temperature of the object to be fired cannot be controlled to the firing conditions according to the kind of the object to be fired.
The invention of Patent Document 2 is provided with a convection device, but discharges the air in the operation kiln from the air discharge tube and cannot send outside air as secondary combustion air into the operation kiln. Since the convection device is installed in the operation kiln, a device such as a blower that can withstand high temperatures is required.
Then, the ambient air in the baking chamber is agitated so that the temperature near the side of the baked confectionery dough conveyed on the top plate by the conveyor to the baking chamber does not become lower than that near the top. However, the surface temperature of the object to be fired cannot be controlled to an appropriate temperature for the time corresponding to the kind of the object to be fired in the initial stage of firing. It is.
The invention of Patent Document 3 does not use a convection heating device, and cannot control the surface temperature of the material to be fired to a firing temperature characteristic that matches the type of the material to be fired in the initial stage of firing. .

  In view of the above problems, the object of the present invention is to blast the air outside the furnace taken in through the suction pipe from the suction port provided outside the furnace by the convection heating device provided in the firing furnace, After increasing the combustion efficiency of the gas burner in the firing chamber and stabilizing the combustion, and further controlling the firing temperature characteristics of the firing object in the early stage of firing, after evaporating the moisture on the surface of the firing object and firing the surface hard An object of the present invention is to provide a tunnel oven that can be baked as a whole.

What achieves the above object is as follows.
(1) A bread provided with a baking furnace extending a predetermined length, a baking chamber formed in the baking furnace and provided with a gas burner, and a conveyor for conveying an object to be fired so as to pass through the baking chamber or A tunnel oven for baking confectionery,
The tunnel oven is connected to the suction port provided outside the firing furnace, the suction port and the firing chamber, the intake pipe for taking air outside the furnace into the firing chamber, and the suction pipe. An air ejection tube having a small hole for ejecting the air outside the furnace taken in toward the object to be fired moving in the firing chamber, a pressure detection unit provided in the suction pipe and detecting a pressure in the pipe, A convection heating device provided in a pipe line of the suction pipe and having a pressure blower for adjusting the pressure in the suction pipe is transferred to the inlet zone of the firing furnace on the side of the firing object to be conveyed. There are several in the direction,
Further, the tunnel oven includes a reference suction pipe pressure value storage unit that stores a reference suction pipe pressure value that matches a firing condition of the object to be fired, and a pressure value detected by the pressure detection unit of each of the convection heating devices. Bread or confectionery baking characterized by having a convection heating device control unit comprising a pressure blower control unit that controls the operation of the pressure blower of each convection heating device using the stored reference suction pipe pressure value Tunnel oven.

(2) The convection heating device controller adjusts the amount of air ejected from the air ejection tube of each of the convection heating devices, and the convection heating device control unit controls The tunnel oven according to the above (1), which controls the amount of high-temperature air flow toward the surface.
(3) The air ejection tube of the convection heating device is provided so as to be substantially orthogonal to the conveying direction of the object to be fired on the conveyor, and further includes a plurality of small holes for ejecting air. Or the tunnel-type oven as described in (2).
(4) The air ejection tube of the convection heating device includes an oblique rear ejection small hole row that ejects air toward an oblique rearward direction in the conveyance direction of the object to be fired, directly below the air ejection tube. The tunnel type oven according to any one of the above (1) to (3), further comprising a slanted front ejection small hole row that ejects air toward a slanting front in the conveying direction of the firing object.

(5) The air ejection tube is disposed at a position close to the ceiling of the combustion chamber so that the air outside the furnace ejected from the small hole convects the hot air in the upper part of the firing chamber. (1) thru | or the tunnel type oven in any one of (4).
(6) The reference suction pipe pressure value storage section stores a plurality of reference suction pipe pressure values suitable for firing conditions of the plurality of objects to be fired, according to any one of (1) to (5). Tunnel oven.
(7) The air jetting tube of the convection heating device jets air at an angle of about 30 degrees forward from the direction immediately below the air jetting tube with respect to the conveying direction of the object to be fired by the belt conveyor. The tunnel oven according to any one of the above (1) to (6), comprising a small hole for discharging and a small hole for ejecting at an angle of about 30 degrees rearward.

(8) A plurality of the convection heating devices are arranged in the entrance zone, the central zone, and the exit zone of the firing furnace so as to face the conveyance direction of the object to be fired and are spaced apart from each other by a predetermined interval. The tunnel oven according to any one of (1) to (7) above.
(9) The tunnel type according to any one of (1) to (8), wherein the pressure blower provided in the pipe line of the suction pipe is provided in the pipe line located outside the firing chamber. oven.
(10) The convection heating device control unit operates one or a plurality of convection heating devices installed in the entrance zone of the baking furnace as needed to act on the surface of the object to be baked. The tunnel oven according to any one of (1) to (9), which controls the amount of high-temperature air flow.

  The tunnel-type oven of the present invention jets air outside the furnace into the combustion chamber by a plurality of convection heating devices provided in the entrance zone on the carry-in side of the firing object of the firing furnace in the conveying direction of the fired object. Therefore, it is possible to supply secondary combustion air containing oxygen sufficiently in the firing chamber, and to stir the secondary combustion air in the firing chamber, to improve the combustion efficiency of the gas burner and to stabilize the combustion. Can do. In the conventional tunnel oven, the supply route of the secondary combustion air is mainly used to supply and exhaust the secondary combustion air from the opening of the entrance / exit of the firing chamber using an intake / exhaust fan. However, since this intake / exhaust amount decreases, heat loss can be suppressed and energy saving can be achieved.

In the tunnel oven of the present invention, the air outside the furnace is ejected from the small hole of the air ejection tube into the firing chamber by the convection heating device, and the convection of the air including the high-temperature air in the firing chamber is created. The convection high-temperature air can be applied to the surface of the object to be fired by the convection heating device control unit, the reference suction pipe pressure value stored in the reference suction pipe pressure value storage unit, and the suction pipe. Based on the pressure value in the pipe detected by the pressure detection unit, the pressure of the pressure blower can be controlled and the pressure can be adjusted via the pressure blower control unit. Corresponding to this kind, the whole surface can be baked after high-temperature air acts on the dough surface at an early stage of firing to evaporate moisture on the surface of the material to be fired and hard-fire the surface.
On the contrary, the convection heating device control unit can bake the surface of the object to be baked without making it harder by gently evaporating the water on the surface of the object to be fired without strongly heating in the initial stage of firing.
In this way, the amount of air ejected from the small hole of the air ejection tube of each convection heating device is adjusted by the convection heating device controller, and the firing initial stage of the object to be fired carried into the firing chamber Because it is possible to control the air volume of high-temperature air toward the surface of the object to be baked, it is easy to control the temperature characteristics at the initial stage of baking to the desired characteristics. It can be fired under the combined firing conditions, and the quality can be improved.

  The tunnel-type oven of the present invention is provided with the air ejection tube of the convection heating device so as to be substantially orthogonal to the conveying direction of the object to be fired on the conveyor, and further includes a plurality of small holes for ejecting air. Therefore, high-temperature air can be made to act evenly on each workpiece to be conveyed.

  The tunnel-type oven of the present invention is a slanting rear jet in which the air jetting tube of the convection heating device jets air toward a diagonally rearward direction in the conveying direction of the object to be fired, directly below the air jetting tube. Since the small hole row for use and the small hole row for oblique forward ejection that ejects air toward the diagonally forward direction in the conveying direction of the object to be fired, the convective high temperature air can be applied to a predetermined range. Since it can act on the surface of the object to be fired substantially continuously for a predetermined time, a large number of objects to be fired that are continuously conveyed by the conveyor can be efficiently fired at a high speed.

  In the tunnel-type oven of the present invention, since the air ejection tube is disposed at a position close to the ceiling of the combustion chamber, the air outside the furnace ejected from a small hole of the air ejection tube is the upper part of the firing chamber. In particular, high temperature air having a high temperature is entangled and convection is performed, so that convection of high temperature air can be generated with high thermal efficiency.

  In the tunnel-type oven of the present invention, the reference suction pipe pressure value storage unit stores a plurality of reference suction pipe pressure values adapted to the firing conditions of the plurality of objects to be baked. Can be fired under suitable firing conditions.

  In the tunnel type oven of the present invention, the direction of the air ejected from the small hole of the air ejection tube of the convection heating device is approximately from the front of the air ejection tube to the forward direction of the object to be fired by the belt conveyor. Since it has a small hole for ejecting at an angle of 30 degrees and a small hole for ejecting at an angle of about 30 degrees rearward, a single convection heating device can be used for a wide range of objects to be fired. The convective hot air can be applied to the surface almost continuously for a predetermined time.

  In the tunnel oven of the present invention, a plurality of the convection heating devices are arranged in the entrance zone of the baking furnace so as to face the conveying direction of the object to be fired and spaced apart by a predetermined distance. It is possible to raise the firing temperature of the product, evaporate the moisture on the surface of the object to be fired at the initial stage of firing, and harden the surface, and then the whole can be baked. Also suitable for other types of products The firing temperature can be controlled.

   In the tunnel type oven of the present invention, the pressure blower is provided in a pipe line of the suction pipe outside the firing chamber whose temperature is significantly lower than that in the firing chamber. There is no need to use it, the price is low, and there are fewer failures.

  In the tunnel oven of the present invention, one or more convection heating devices installed in the entrance zone of the firing furnace can be operated as needed by the convection heating device control unit. The firing temperature characteristics can be adjusted over a wide range by controlling the amount of high-temperature air applied to the surface of the object to be fired and adjusting the number of bases on which the convection heating device operates.

FIG. 1 is an enlarged explanatory view of an entrance zone portion of a tunnel oven according to the present invention. FIG. 2 is an explanatory diagram of the tunnel oven according to the present invention. FIG. 3 is a cross-sectional view of the air ejection tube. FIG. 4 is a longitudinal sectional view of the air ejection tube. FIG. 5 is a diagram showing the temperature characteristics of the surface temperature and the atmospheric temperature in the initial stage of firing of the object to be fired according to the present invention.

The tunnel oven according to the present invention will be described with reference to the embodiments shown in the drawings.
1 and 2, A is a baking furnace for baking bread and confectionery extending a predetermined length, and in the baking furnace A, a baking chamber B having a gas burner 7 and the like is provided, and the baking furnace A is , An entrance zone a, a central zone b, and an exit zone c.
The baking furnace A is provided with a conveyor 12 for transporting an object to be baked 10 such as bread dough and confectionery dough so as to pass through the baking chamber B. The to-be-fired object 10 placed on the tray 11 is carried in, heated and fired while passing through the inlet zone a, the central zone b, and the outlet zone c, and the to-be-fired object has been fired from the carry-out port 9 of the firing furnace A 10 is carried out.

C is a convection heating device, and, as shown in FIGS. 1 and 2, the entrance zone a on the carry-in side of the firing furnace A is directed from the carry-in entrance 8 of the firing furnace A to the carry-out exit 9 of the firing furnace A. That is, three convection heating devices C are installed in order in the transport direction of the object to be fired 10.
Although each convection heating device C is installed at a predetermined interval, in order to make high-temperature air easily act on the surface of the object to be fired 10 in the initial stage of firing, the first convection heating on the carry-in side is performed. The apparatus is installed near the carry-in entrance 8, and the first convection heating device C and the second convection heating device C are also installed with a small interval therebetween, and the second and third convection heating devices C are installed. The distance from the convection heating device C is set slightly wider.
Three or more convection heating devices C are installed, but more than that may be used, and only one convection heating device or only two convection heating devices may be used as necessary by a convection heating device controller D described later, or Three units are controlled to operate.

Each of the three convection heating devices C includes a mechanism for supplying the air outside the furnace to the firing chamber B and a mechanism for controlling the amount of the air outside the furnace ejected into the firing chamber.
The former mechanism for supplying the air outside the furnace to the firing chamber B includes a suction port 1 for sucking the air outside the furnace, the suction port 1 and the firing chamber B communicating with each other, and the air outside the furnace is supplied to the firing chamber B. A suction pipe 2 to be taken in, a pressure blower 5 such as a blower which is inserted and installed in a pipe line of the suction pipe 2 and blows air by adjusting the pressure inside the suction pipe 2, and outside air taken in by the suction pipe 2 In the firing chamber B, and an air ejection tube 3 provided with a small hole 4 ejected toward the object to be fired 10 conveyed by the conveyor 12.
The suction port 1 is installed outside the firing furnace A and is provided in communication with the upper end of the suction pipe. Further, the lower end of the suction pipe is connected to the air ejection tube 3 installed at a position close to the ceiling 13 of the baking chamber B.

The latter mechanism for controlling the amount of air blown out of the furnace into the combustion chamber includes a pressure detector 6 such as a pressure gauge attached to the suction pipe 2 for detecting the pressure in the suction pipe 2, and the suction pipe. 2, a pressure blower 5 such as a blower for adjusting the in-pipe pressure, and a convection heating device controller D.
In addition, the convection heating device control unit D includes a reference suction pipe pressure value storage unit that stores a reference suction pipe pressure value that conforms to the firing conditions of the article 10, and a pressure value detected by the pressure detection unit 6. A pressure blower control unit that controls the pressure blower 5 based on a reference suction pipe pressure value stored in the storage unit is provided.
The pressure detector 6 such as a pressure gauge, the pressure blower 5 such as a blower, and the convection heating device controller D are not installed in the firing chamber B having a high temperature, but are all outside the firing furnace A. is set up.

  The convection heating device control unit D is electrically connected to the pressure blower 5 and the pressure detection unit 6 of the convection heating device C, and corresponds to the type of bread dough / confectionery dough to be baked. A reference suction pipe pressure value suitable for the article to be fired 10 is selected from the reference suction pipe pressure values of the plurality of articles to be fired 10 that have been input and stored in advance in the pressure value storage unit. A reference suction pipe internal pressure value is compared with the pressure value detected by the pressure detection unit 6, and the operation of the pressure blower 5 is controlled and sucked via the pressure blower control unit of the convection heating device control unit D. The pressure in the tube is adjusted, the amount of air blown out from the small hole 4 of the air blowing tube 3 of each of the convection heating devices C is adjusted, and the object to be fired 10 carried into the firing chamber B in the initial stage of firing. High-temperature sky toward the surface of the fired product It is intended to control the air flow.

A pressure blower 5 such as the blower of the convection heating device C is installed in a pipe line of the suction pipe 2, and the suction pipe is controlled by a control signal from the pressure blower control unit of the convection heating device control unit D. 2 and the pressure in the air ejection tube 3 can be adjusted. And when the pressure in the said air blower tube 3 is the diameter of the said small hole 4 being 1 mm, the said pressure blower 5 makes the pressure in the said suction pipe 2 of the said convection heating apparatus C 10 kpa-60 kpa. It can be adjusted within the range.
The pressure blower 5 such as a blower is installed in the path of the suction pipe 2, and the pressure detection unit 6 such as the pressure gauge is attached to the suction pipe 2 on the downstream side of the pressure blower 5. Yes.

3 and 4 are a transverse sectional view and a longitudinal sectional view of the air ejection tube 3, and the air ejection tube 3 is provided with a plurality of small holes 4 that eject air toward the object to be fired 10. Has been.
As shown in FIG. 3, the small hole 4 is formed on the line 10 at a 30 ° angle (a depression angle 60 °) to the left from the center of the transverse section of the air ejection tube 3. An oblique rear ejection small hole array for ejecting air toward the oblique rear in the conveyance direction is provided, and oblique to the firing direction of the article 10 on a line at an angle of 30 ° to the right with respect to immediately below. Diagonal forward ejection small hole arrays for ejecting air toward the front are provided, and convection of high-temperature air is generated in a square shape as shown in FIG.
The size of the small hole 4 and the position to be drilled are provided on the small hole 4 provided on the line at an angle of 30 ° to the left with respect to the direct lower side and on the line at an angle of 30 ° to the right with respect to the direct lower side. As shown in FIG. 4, the small holes 4 are arranged at a middle position between the adjacent small holes 4 provided on the line with an angle of 30 ° on the left and on a line with an angle of 30 ° on the right. The provided small holes 4 are positioned so that the interval between the adjacent small holes 4 and the small holes 4 is 120 mm to 160 mm, preferably 150 mm. Moreover, the diameter of the small hole 4 is 0.5 mm-1.5 mm, Preferably it is 1 mm.

The air ejection tube 3 of the convection heating device C is provided across the firing chamber B so as to be substantially orthogonal to the conveying direction of the object 10 to be fired on the conveyor 12, and the small holes 4 have the positional relationship. High-temperature air is uniformly applied to all of the objects to be fired 10 arranged in a plurality of rows arranged and carried on the tray 11 by the conveyor 12.
In addition, the air ejection tube 3 is configured so that the air ejected from the small hole 4 entrains the hot air staying in the vicinity of the ceiling 13 at the upper part of the firing chamber so that the hot air can be convected. It is installed at a position close to the ceiling 13 of the combustion chamber.

  Since the present invention is configured as described above, the convection heating device sucks air outside the furnace and blows it out of the air blowing tube into the firing chamber, so that air sufficiently containing oxygen outside the furnace is contained. Since it can be supplied to the gas burner as secondary combustion air and the air in the firing chamber is agitated, the combustion efficiency of the gas burner can be improved and stable combustion can be achieved. In addition, since the amount of secondary combustion air taken in or discharged from the inlet / outlet of the baking chamber by an intake / exhaust fan or the like is reduced as in the prior art, in addition to reducing temperature unevenness in the baking chamber, By agitating the air, the high-temperature air that has conventionally existed in the vicinity of the ceiling as a heat reservoir is made uniform in the firing chamber, and the energy loss can be reduced by exhausting the low-temperature air. it can.

Further, according to the present invention, the convection heating device causes air outside the furnace to be ejected from a small hole of the air ejection tube toward the object to be fired, and convection of high temperature air in which high temperature air in the firing chamber is entrained is generated. It is possible to adjust the amount of hot air flow on the surface of the object.
Therefore, according to the present invention, the firing temperature of the object to be fired is adjusted first by adjusting the atmosphere temperature of the firing chamber by the combustion control of the gas burner, and secondly, it is conveyed by the conveyor by the convection heating device. Since the amount of high-temperature air that acts on the object to be fired is adjusted, the upper surface temperature of the material to be fired at the initial stage of firing is controlled to an appropriate temperature on the upper surface of the material as time passes, that is, the material to be fired is moved by the conveyor. be able to.

FIG. 5 shows the relationship between the pressure change in the suction pipe and the air jet tube of the convection heating device, the atmosphere temperature in the baking chamber and the top surface temperature of the baking chamber when the diameter of the small hole drilled in the air jet tube is 1 mm. Of the three convection heating devices as shown,
(A) The pressure of the air jet tube of the second convection heating device (No. 2) is 35 kPa from the carry-in side of the firing object of the firing furnace, and the air jet of the third convection heating device (No. 3). The temperature characteristics when the tube pressure is 50 kPa and the first convection heating device (No. 1) is stopped are shown in (1-1) Atmosphere and (1-2) Upper surface of the object to be fired. In addition, the ambient temperature continued to rise almost linearly from about 30 ° C to about 205 ° C in 6 minutes from the start of firing, and then gradually decreased from 205 ° C to around 160 ° C from 6 minutes to 10 minutes. Thereafter, stable temperature characteristics are shown at around 160 ° C.
The upper surface temperature of the object to be fired starts to gradually rise from about 30 ° C. to about 50 ° C. for 2 minutes from the start of firing, and rapidly rises to about 140 ° C. from 2 minutes to 5 minutes to 6 minutes. .

(B) The pressure of the air jet tube of the second convection heating device (No. 2) is 20 kPa from the carry-in side of the firing object of the firing furnace, and the air jet of the third convection heating device (No. 3). The temperature characteristics when the tube pressure is 20 kPa and the first convection heating device (No. 1) is stopped are shown in (2-1) Atmosphere and (2-2) Upper surface of the object to be fired. In addition, after the ambient temperature has continued to rise almost linearly from about 30 ° C to about 105 ° C in 2 minutes from the start of firing, the temperature rise becomes moderate and a parabola is applied from about 105 ° C to about 150 ° C in 2 minutes to 6 minutes. It rises like drawing and then changes around 150 ° C. and keeps the temperature.
The upper surface temperature of the object to be baked gradually increases from about 30 ° C. to about 100 ° C. for 6 minutes from the start of baking, and further increases gradually after about 6 minutes, and about 30 ° C. after 6 to 16 minutes. The temperature characteristic rises and changes at about 130 ° C.

(C) The pressure of the air jet tube of the first convection heating device (No. 1) is 50 kPa from the inlet side of the firing object of the firing furnace, and the air jet of the second convection heating device (No. 2). The temperature characteristics when the pressure of the tube is 30 kPa and the pressure of the air jet tube of the third convection heating device (No. 3) is 20 kPa are: (3-1) atmosphere, (3-2) top surface of the object to be fired As shown in, after the ambient temperature continued to rise almost linearly from about 30 ° C. to about 178 ° C. in 3 minutes from the start of firing, it decreased to 170 ° C. in 3 to 4 minutes from the start of firing. Thereafter, the temperature changes from 160 ° C. to 170 ° C. and maintains the temperature.
The upper surface temperature of the object to be fired reaches about 50 ° C. in about 1 minute and 40 seconds from the start of firing, reaches 78 ° C. in 2 minutes and 30 seconds, and reaches about 100 ° C. in 3 minutes, and the temperature rapidly rises from the start of firing. After that, the temperature continued to rise and reached 130 ° C. in 5 minutes and 25 seconds, and thereafter changed from 120 ° C. to 130 ° C.

As is apparent from the above temperature characteristics, by controlling the convection heating device, the upper surface temperature of the object to be baked is rapidly increased or gently increased in the baking process for about 6 minutes from the start of baking. Stepwise firing temperature characteristics are obtained.
Therefore, the present invention does not simply provide the convection heating device so that the air in the baking chamber is uniformly stirred and the temperature is uniformed, and the heat acts equally on the surface of the object to be baked. It is possible to obtain various firing temperature characteristics in the initial stage of firing by selecting the position of the convection heating device in the firing furnace, setting the pressure value of the air ejection tube, etc. Depending on the type, optimum firing conditions can be provided, and firing is performed under such conditions, so that a product with a good appearance and volume can be provided.

  In particular, in the case of melon bread, by controlling the above (c), it becomes possible to rapidly heat the dough surface at the beginning of baking, and the dough surface temperature reaches 100 ° C. in 3 minutes from the start of baking. Therefore, the amount of water evaporated from the surface of the fabric after 3 minutes has increased, and after the surface of the fabric is evaporated and the surface is hard baked, the whole object to be baked is baked to make it tall and plump After baking, the melon bread with clear baked color can be baked. In addition, for the baking of Danish, pie, and croissant, a product of good quality can be baked by the control of (c).

  In addition, the pressure blower such as the blower of the convection heating device of the present invention, the pressure detection unit such as the pressure gauge, and the convection heating device control unit are installed outside the furnace at a low temperature outside the firing chamber. Therefore, it is not necessary to take measures for these heat resistances, and it is not necessary to use expensive heat-resistant equipment.

A Firing furnace B Firing chamber C Convection heating device D Convection heating device controller a Inlet zone b Central zone c Outlet zone 1 Intake port 2 Intake tube 3 Air ejection tube 4 Small hole 5 Pressure blower 6 Pressure detection unit 7 Gas burner 8 Carrying-in port 9 Carrying-out port 10 To-be-baked thing 11 Tray 12 Conveyor 13 Ceiling

Claims (10)

For baking bread or confectionery comprising a baking furnace extending for a predetermined length, a baking chamber formed in the baking furnace and provided with a gas burner, and a conveyor for transporting an object to be baked so as to pass through the baking chamber Tunnel oven,
The tunnel oven is connected to the suction port provided outside the firing furnace, the suction port and the firing chamber, the intake pipe for taking air outside the furnace into the firing chamber, and the suction pipe. An air ejection tube having a small hole for ejecting the air outside the furnace taken in toward the object to be fired moving in the firing chamber, a pressure detection unit provided in the suction pipe and detecting a pressure in the pipe, A convection heating device provided in a pipe line of the suction pipe and having a pressure blower for adjusting the pressure in the suction pipe is transferred to the inlet zone of the firing furnace on the side of the firing object to be conveyed. There are several in the direction,
Further, the tunnel oven includes a reference suction pipe pressure value storage unit that stores a reference suction pipe pressure value that matches a firing condition of the object to be fired, and a pressure value detected by the pressure detection unit of each of the convection heating devices. Bread or confectionery baking characterized by having a convection heating device control unit comprising a pressure blower control unit that controls the operation of the pressure blower of each convection heating device using the stored reference suction pipe pressure value Tunnel oven. The convection heating device control unit adjusts the amount of air ejected from the air ejection tube of each convection heating device, and moves toward the surface of the material to be fired at the initial stage of firing of the material to be fired carried into the firing chamber. The tunnel type oven according to claim 1, which controls a high-temperature air flow rate. The said air ejection tube of the said convection heating apparatus is provided so that it may be substantially orthogonal to the conveyance direction of the to-be-fired thing of a conveyor, Furthermore, it equips with the several small hole which ejects air. Tunnel oven. The air ejection tube of the convection heating device includes an oblique rear ejection small hole row that ejects air toward an oblique rearward direction in the conveying direction of the object to be fired, directly below the air ejection tube; The tunnel type oven according to any one of claims 1 to 3, further comprising a slant forward jet small hole array that spouts air toward a slant front in a conveying direction of the fired product. The said air ejection tube is arrange | positioned in the position close | similar to the ceiling of the said combustion chamber so that the air outside the furnace ejected from the said small hole may convect the hot air of the upper part of the said firing chamber. 4. The tunnel oven according to any one of 4 above. The tunnel type oven according to any one of claims 1 to 5, wherein the reference suction pipe pressure value storage unit stores a plurality of reference suction pipe pressure values suitable for firing conditions of a plurality of objects to be fired. The air ejection tube of the convection heating device is small in order for the air ejection direction to be ejected at an angle of about 30 degrees forward with respect to the conveying direction of the object to be baked by the belt conveyor from directly below the air ejection tube. The tunnel type oven according to any one of claims 1 to 6, further comprising a hole and a small hole for ejecting at an angle of about 30 degrees rearward. A plurality of the convection heating devices are arranged in an entrance zone among the entrance zone, the central zone, and the exit zone of the firing furnace so as to be directed in the conveying direction of the object to be fired and spaced apart from each other by a predetermined interval. The tunnel type oven according to any one of 7 to 7. The tunnel type oven according to any one of claims 1 to 8, wherein the pressure blower provided in a pipe line of the suction pipe is provided in the pipe line located outside the baking chamber. The convection heating device control unit operates a plurality of convection heating devices installed in the entrance zone of the firing furnace as needed to operate one or a plurality of devices and act on the surface of the object to be fired. The tunnel type oven according to any one of claims 1 to 9, which controls the above.

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