JP2009019784A - Continuous baking furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a continuous baking furnace capable of preventing diffusion of a reaction product gas to an outlet side of a furnace body while suppressing a flow rate of a reaction gas. <P>SOLUTION: This continuous baking furnace comprises the furnace body 2, a roller conveyor 3 for conveying a baked object W from a carry-in port to a carry-out port, a plurality of heaters, an introduction pipe for introducing the reaction gas G into the furnace body, an exhaust pipe for exhausting the gases G, G1 in the furnace body to the outside of the furnace body, and a reaction gas recovering pipe 10 disposed on an inner wall surface of a furnace body side wall 2a along the longitudinal direction of the furnace body in a region where the reaction product gas G1 generates by the reaction of the baked object W and the reaction gas G, having a plurality of suction holes 10a in the longitudinal direction of an outer peripheral face, and exhausting the gases G, G1 to the outside of the furnace body through the suction holes. The reaction gas recovering pipe is disposed at a certain height within a range from a top face of the baked object to a heater disposed at an upper part of the roller conveyor. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a continuous firing furnace for firing a material to be fired to obtain a fired product.

  Conventionally, a tunnel furnace is used as a continuous firing furnace for firing a material to be fired to obtain a fired product. A schematic cross section of such a continuous firing furnace is shown in FIG. The ceiling, side walls, and hearth constituting the furnace body 2 of the continuous firing furnace 1 are formed of a heat-resistant material such as brick or heat-resistant steel. The furnace body is provided with a conveying means 3 such as a roller conveyor or a belt conveyor, and the object to be fired W or the container containing the object to be fired W is placed on the means for conveying 3 and carried from the carry-in entrance, The fired product W is carried out from the carry-out port as a fired product.

  As described in Patent Document 1 (Japanese Patent Laid-Open No. 47-25210) and Patent Document 2 (Japanese Patent Laid-Open No. 1-252886), the furnace body includes partition means such as a shutter, a partition door, or a partition plate. 4 is divided into a preheating zone, a firing zone, and a slow cooling zone. Each zone is subjected to temperature management necessary for each zone by a heater H using infrared rays or the like and a temperature control device (not shown).

  An introduction pipe 5 is provided on the carry-out side, that is, on the slow cooling zone of the furnace body 2 in order to supply the reaction gas G necessary for firing. On the other hand, an exhaust pipe 6 for exhausting the reaction gas G and the reaction product gas G1 generated by firing is provided on the carry-in side, that is, the preheating zone of the furnace body 2.

  In the continuous firing furnace 1, it is important to prevent the product after firing from being contaminated by a reverse reaction with the reaction product gas G1. For this reason, a gas flow of the reactive gas G from the carry-out port toward the carry-in port is generated. The introduced reaction gas G is used not only for the firing reaction but also for discharging the reaction product gas G1. For this reason, an amount of reaction gas G larger than that required for the firing reaction is introduced.

  In the continuous firing furnace 1, the reaction gas G is preferably supplied to the entire region in the furnace body. If there is a region where the supply is not spread, the reaction product gas G1 is stagnated. For example, if such a region is present, not only the firing reaction does not proceed in the firing zone but also the reverse reaction may occur in the slow cooling zone. Sex occurs.

  In order to prevent the stagnation of the reaction product gas G1, conventionally, a plurality of introduction pipes are provided in the slow cooling zone and the firing zone to strengthen the gas flow from the carry-out side to the exhaust pipe, The reaction gas is supplied as close to the raw material as possible (not shown).

  However, when the reaction gas is supplied in this way, a number of vortices are generated locally. Therefore, in order to eliminate the generation of vortices and secure the basic gas flow in the furnace, In each case, the gas flow rate to be introduced must be adjusted accurately, and advanced technology and skill are required.

Even with such adjustment, the vortex is not completely eliminated, and adjustment that prevents the diffused reaction product gas from approaching the carry-out side is the limit. Also, if the gas flow rate is reduced to prevent the generation of vortices, the reaction product gas diffuses and flows to the carry-out side, so to adjust the reaction product gas so that it does not approach the carry-out side, It is necessary to introduce a large amount of reaction gas. As described above, in the conventional continuous firing furnace, it is extremely difficult to appropriately control the conditions in the furnace body.
JP 47-25210 A JP-A-1-252886

  An object of the present invention is to provide a continuous firing furnace that does not require high-level control and can prevent the reaction product gas from diffusing to the carry-out side of the furnace body while keeping the flow rate of the reaction gas low. To do.

The continuous firing furnace according to the present invention is:
A furnace body having a carry-in port and a carry-out port communicating with the carry-in port in the furnace body;
A transport means for transporting an object to be fired or a container containing the object to be fired from a carry-in port to a carry-out port;
A plurality of heating means provided in the furnace body;
An introduction pipe provided in the furnace body on the carry-out side, for introducing the reaction gas into the furnace body;
An exhaust pipe provided in the furnace body on the carry-in side, for exhausting the gas in the furnace body to the outside of the furnace body;
In the region where the reaction product gas is generated by the reaction between the object to be fired and the reaction gas,
A reaction that is provided along the longitudinal direction of the furnace body on the inner wall surface of the furnace body side wall, has a plurality of suction holes in the longitudinal direction of the outer peripheral surface, and exhausts reaction gas and reaction product gas out of the furnace body through the suction holes. A gas recovery pipe;
With
The reaction gas recovery pipe is arranged at a height within a range from the upper surface of the object to be fired to the heating means provided above the conveying means.

  The reaction gas recovery pipe is preferably provided on each of the inner wall surfaces of the left and right furnace body side walls.

  Further, it is preferable that a reaction gas supply pipe for spraying the reaction gas downward is provided on the upper part of the furnace body.

  In the continuous firing furnace of the present invention, the reaction product gas can be smoothly discharged in the reaction product gas generation region in the furnace body, so that the phenomenon that the reaction product gas diffuses in the furnace body and flows to the discharge port side is sufficient. It is possible to suppress the flow rate of the reaction gas flowing through the entire furnace body, and it becomes unnecessary to control the flow rate of the reaction gas at a high level.

  As a result of intensive studies, the present inventor has obtained knowledge that the following phenomenon occurs in the conventional continuous firing furnace.

  That is, in order to promote the firing reaction of the object to be fired, a reaction gas introduced from a large number of introduction pipes is sprayed toward the object to be fired, and the flow rate of the sprayed reaction gas flows through the entire furnace body. The reaction gas or reaction product gas that bounces off and repels the object to be fired or the fired product is vortexed (rotated) and becomes turbulent, causing complexity in the gas flow. .

  Such a complicated gas flow forms a flow that runs up to the ceiling and a flow that blows down from the ceiling to the object to be fired along the side wall of the furnace wall, and at the same time from the end of the roller of the roller conveyor as a conveying means. A flow that flows downward or a flow that blows from the lower side of the roller through the gap between the rollers is formed.

  In such a state, if the flow of gas from the carry-out port to the carry-in port that occurs above the roller is accelerated to prevent a reverse reaction between the calcined product and the reaction product gas, the roller upper side is below the roller. Contrary to this flow, a flow from the carry-in port to the carry-out port occurs.

  For this reason, the reaction product gas generated on the surface of the object to be fired moves and diffuses in a turbulent state while forming the vortex described above, and joins the flow that flows from the end of the roller to the lower side of the roller, Head to the bottom of the furnace. Furthermore, the gas flows from the carry-in port to the carry-out port below the furnace body, is carried to the vicinity of the carry-out port, and blows out from the lower side of the roller through the gap between the rollers to the upper side of the roller.

  Due to the above phenomenon, even if the gas flow is directed from the carry-out port to the carry-in port on the upper side of the roller, a part of the reaction product gas diffuses to the vicinity of the carry-out port, and the fired product and the reaction product gas As a result, the reverse reaction occurs.

  The present inventors have completed the present invention based on such findings. The continuous firing furnace according to the present invention will be described below with reference to the drawings. The basic structure of the continuous firing furnace 1 is the same as the conventional structure shown in FIG. Therefore, the description of the basic structure is omitted, and the same reference numerals are given to the same members.

  1 and 2 show the internal structure of a continuous firing furnace 1 according to the present invention. The illustrated one uses a roller conveyor 3 as a conveying means. In the roller conveyor 3, a large number of rollers 3 a are arranged and arranged, for example, a flat plate 7 on which a mortar 8 is placed can be placed, and the object to be fired W is accommodated in the mortar 8.

  In the furnace body, a plurality of heaters H as heating means are provided above and below the roller conveyor 3 along the longitudinal direction of the furnace body.

  In the continuous firing furnace 1 according to the present invention, in the region where the reaction product gas is generated by the reaction between the object to be fired W and the reaction gas, on the left and right inner wall surfaces of the furnace body side wall 2a along the longitudinal direction of the furnace body. The reaction gas recovery pipe 10 is provided horizontally. More specifically, the reaction gas recovery pipe 10 is arranged at a height within a range from the upper surface of the workpiece W to the heater H provided above the roller conveyor 3.

  In the reaction product gas generation region, basically, the product to be fired W and the reaction gas react in the firing zone under conditions of, for example, a furnace temperature of 600 ° C. and an oxygen concentration of 95% to produce a reaction product as a by-product. An area where gas is generated. Also, in the preheating zone, the object to be fired W and the reaction gas may react to generate a reaction product gas generation region. The position and length of the reaction product gas generation region are determined by the content of the object to be fired W, the type of reaction gas, the operating conditions, and the like, and the position and length may be determined from the previous conditions.

  The reaction gas recovery pipe 10 is made of a heat resistant material such as heat resistant steel or SUS304. As described above, the length of the reaction gas recovery pipe 10 varies depending on the application of the continuous firing furnace 1, but the length may be approximately the same as the reaction gas generation region. However, it is allowed to have some length compared to the reaction gas generation region. Of course, it is preferable to install the reaction gas recovery pipe 10 over the entire region of the reaction gas generation region.

  Further, as the reaction gas recovery pipe 10, a tubular member having a diameter of about 50 to 100 mm and an outer peripheral portion of about 1 to 2 mm can be used.

  Suction holes 10 a for sucking the reaction gas G are formed on the outer peripheral surface of the reaction gas recovery pipe 10 at intervals. The shape of the suction hole 10a may be a circular shape or an elliptical shape. The size of the suction hole 10a is, for example, about φ3 to 20 mm in the case of a structure having a circular hole. In this case, the suction holes 10a are formed at intervals of 10 to 500 mm. With respect to the arrangement of the suction holes 10a, there is a degree of freedom to change the angle around the central axis of the reaction gas recovery pipe 10, but from the viewpoint of ease of suction, the reaction gas so that the suction holes 10a face the side to be fired. It is preferable to arrange the recovery tube 10.

  When the suction holes 10a of the reaction gas recovery pipe 10 are formed at regular intervals, the reaction product gas G1 generated in a wide range in the furnace can be efficiently recovered at a substantially uniform flow rate.

  The reaction gas recovery pipe 10 is connected to an exhaust pump, and sucks the reaction product gas and a part of the reaction gas through the suction hole 10a with the internal pressure lowered. If the suction hole 10a is too large, the pressure distribution inside the reaction gas recovery pipe is increased, and the suction force of each suction hole is different. Therefore, it is important that the diameter of the suction hole is set to an appropriate size according to the diameter of the reaction gas recovery pipe 10.

  A configuration in which narrow tubes shaped to extend the suction holes 10a vacant in the reaction gas recovery tube 10 are arranged in parallel and recovered near the reaction product gas generation region is also effective depending on the state in the furnace. Is. In addition, in order to collect high concentration product gas intensively in the generation region, a method of separately providing a reactive gas recovery pipe having a strong suction force in the vicinity thereof may be considered. In some cases, it may be effective to add lattices or meshes to the suction holes to adjust the flow velocity in each suction hole, or to adjust the hole diameter according to the flow velocity.

  Only one reaction gas recovery pipe 10 is provided on at least one side of the left and right furnace body side walls 2a. The reaction gas recovery pipe 10 is disposed on the upper surface of the workpiece W conveyed by the roller conveyor 3 or at a position higher than the upper surface. That is, in the space above the roller conveyor 3 in the furnace, it is disposed at an arbitrary position up to the heater H disposed above the object to be fired W. When only one reaction gas recovery pipe 10 is disposed, a part of the reaction product gas released from the upper surface of the mortar 8 is diffused by the flow of the reaction gas in a region far from the reaction gas recovery pipe 10. A part of the air is sucked slowly at first and then as the flow velocity increases toward the suction hole 10a.

  Further, the specific determination of the height of the reaction gas recovery pipe 10 is based on the fact that the lower part of the suction hole 10a and the upper end of the bowl 8 are brought close to each other to form a wide low pressure region on the bowl. Specifically, when the height and width of the furnace body are each 2 m, the furnace body is preferably disposed at a height of about ± 5 mm from the upper surface of the workpiece W.

  Preferably, one reaction gas recovery pipe 10 is provided on each side of the left and right furnace body side walls 2a. The reaction gas recovery pipes 10 are provided so as to face each other at the height position of the upper surface of the object to be fired W or at a position higher than that. In this case, the reaction product gas generated from the upper surface of the mortar heads to the recovery tube which is closer to the left or right.

  Furthermore, it is preferable to provide a plurality of reaction gas recovery pipes 10 on both sides of the left and right furnace body side walls 2a.

  The reaction product gas G1 and the unreacted reaction gas G recovered from the suction hole 10a are discharged out of the furnace body through the reaction gas recovery pipe 10.

  In order to reinforce the flow of the gas for recovering the reaction product gas G1, it is preferable that a reaction gas supply pipe 11 for spraying the reaction gas G downward is provided on the upper part of the furnace body.

  The reactive gas supply pipe 11 and the reactive gas recovery pipe 10 are made of a heat resistant material such as heat resistant steel or SUS304. The reaction gas supply pipe 11 and the reaction gas recovery pipe 10 may be tubular members having a diameter of about 50 to 100 mm and an outer peripheral portion of about 1 to 2 mm.

  On the outer peripheral surface of the reaction gas supply pipe 11, ejection holes 11 a for supplying the reaction gas G are formed at a large number of intervals. The shape of the ejection hole 11a may take a shape such as a circle or an ellipse. For example, in the case of a structure having a circular hole, the size of the ejection hole 11a is about φ3 to 20 mm. In this case, the ejection holes 11a are formed at intervals of 10 to 500 mm.

  In addition, in this invention, the upper part in a furnace body means the space between the heater H installed above the roller conveyor 3, and the ceiling of a furnace body.

  The reaction gas supply pipes 11 are preferably arranged along the width direction of the furnace body. Specifically, the reaction gas supply pipe 11 is provided so as to span the left and right furnace body side walls 2a along the width direction of the furnace body. In addition, it arrange | positions so that the position may not overlap with the heater H installed in the downward direction so that the flow of the ejected reactive gas G may not be inhibited. The reason for installing the heater H not in the longitudinal direction but in the width direction is to arbitrarily set the furnace temperature distribution along the longitudinal direction. In that case, although the flow from the carry-out side and the heater H interfere, the diameter of the heater H is as thin as about φ10 mm, so the influence on the flow is small.

  With such a configuration, the reaction product gas G1 is not only discharged from the exhaust pipe 6 along the flow from the introduction pipe 5 to the exhaust pipe 6, which is the entire flow in the furnace body, but also on the roller conveyor. It is sucked into the reaction gas recovery pipe 10 and discharged to the outside in a relatively high concentration state on the flow drawn into the reaction gas recovery pipe 10 which is a partial flow. Therefore, the reaction product gas G1 can be quickly eliminated without diffusing into the furnace, and the adjustment of the introduction amount of the reaction gas G into the introduction pipe 5 becomes easy. Further, the concentration of the reaction product gas G1 around the object to be fired W is greatly reduced, and the object to be fired W is fired well.

(Example)
FIG. 3 shows a longitudinal section of the continuous firing furnace of this example. In this embodiment, oxygen is used as a reaction gas for firing nickel oxide and lithium hydroxide.

  The continuous firing furnace 1 is a furnace body 2 having a cylindrical tunnel (width of about 1000 mm × height of about 1000 mm) composed of a ceiling made of refractory bricks, side walls and a hearth. A large number of roller conveyors 3 in which a large number of rollers are arranged at equal intervals in the longitudinal direction of the continuous firing furnace 1 and a number of partition plates 4 for dividing the furnace body into a large number of zones are provided in the furnace body. In the upper part of the outlet side of the furnace body 2, an introduction pipe 5 for supplying a reaction gas is provided. In addition, exhaust pipes 6 for exhausting the reaction gas in the furnace body are provided at various locations on the inlet side upper part of the furnace body 2.

  In addition, a reaction gas supply pipe 11 for blowing a reaction gas downward is appropriately provided in the upper part of the furnace body. The reaction gas supply pipe 11 is made of SUS304, has an outer diameter of φ20 mm and an inner diameter of φ16 mm. The reaction gas supply pipe 11 has a length of about 1 m, and φ4 mm ejection holes are formed at 20 locations at intervals of about 2 cm on the outer peripheral surface, and is connected to the gas pipe of the supply source. The reaction gas supplied from the reaction gas supply pipe 11 is the same type as the reaction gas G supplied from the introduction pipe 5.

  A to-be-baked material is conveyed by the roller conveyor 3 in the state accommodated in the mortar (300 mm x 300 mm x 100 mm), and moves in a furnace body.

  The heaters H for raising the temperature inside the furnace are respectively arranged above and below the roller conveyor 3, and the mortar and the material to be fired that is contained therein are heated by the radiant heat from the upper and lower heaters H.

  In the region R in the furnace body, reaction gas recovery pipes 10 are provided on the inner wall surfaces of the left and right furnace body side walls along the longitudinal direction of the furnace body. The reaction gas recovery tube 10 was made of a stainless material and had a length of 1000 mm, an outer diameter of 70 mm, and an inner diameter of 66 mm. In addition, φ5 mm suction holes are formed in the reaction gas recovery pipe 10 at 10 positions at regular intervals (8 cm). Then, the reaction gas staying in the region R is sucked into a suction hole formed on the outer peripheral surface of the reaction gas recovery pipe 10. This region R has a length of about 1 m and is a portion heated to 400 to 800 ° C.

A reaction gas of 3 m ³ / hr was supplied from the introduction pipe 5. In the furnace body, a basic reaction gas flow at a speed of about 0.1 m / sec from the outlet side to the inlet side occurred. Next, supply of the reaction gas from the reaction gas supply pipe 11 on the upper side of the furnace was started. The supply amount was 3 m ³ / hr / tube, and the ejection speed from the ejection holes was 3 m / sec.

  The material to be fired was carried into a continuous firing furnace at a speed of 1 m / hr, and the material to be fired was heated at a temperature of 400 to 800 ° C. in the firing zone and fired. The flow distribution of the reaction gas and reaction product gas at this time was observed.

  As a result, the reaction gas introduced from the introduction pipe 5 and the reaction gas supply pipe 11 was sucked into the reaction gas recovery pipe 10 by the pressure in the high temperature furnace. A part of the recovered gas was sampled, and it was confirmed that the reaction gas was recovered by composition analysis.

(Comparative Example 1)
In Comparative Example 1, the same furnace body 2 as in the example was used, and the region R in which the reaction product gas was generated was also the same. A slit having a width of about 1 m × 50 mm was formed along the horizontal direction at the same height as the surface of the object to be fired on one side wall of the furnace body. The slit was provided in the center of the side surface of a stainless steel box having a length of 1.2 m, a height of 150 mm, and a thickness of 50 mm installed in the furnace. The box was connected to the pump via a pipe. This slit serves as a recovery port for the reaction product gas. Note that no reaction gas recovery pipe was provided on the side wall of the furnace body.

  When the flow of the reaction product gas is observed using the above continuous firing furnace 1, a part of the reaction gas is recovered from the slit, but most of the reaction gas rises in the furnace body and becomes integrated with a large vortex. Diffused. That is, the concentration of the reaction product gas around the object to be fired could not be reduced as compared with the example.

(Comparative Example 2)
Using the conventional continuous firing furnace 1, firing was performed under the same conditions as in the examples. When the flow of the reaction product gas was observed, the reaction product gas diffused throughout the furnace body, and then a part of the reaction product gas rides on the basic flow from the carry-out side to the carry-in side, and the exhaust pipe 6 More discharged outside. However, a part of the reaction product gas diffuses to the carry-out port side, and the fired product after the operation has dirt that shows a reverse reaction with the reaction product gas, and cannot be provided as a product.

It is explanatory drawing which shows roughly one Embodiment of the continuous baking furnace of this invention. It is a perspective view which shows the internal structure of the continuous baking furnace of FIG. It is a perspective view which shows the Example of the continuous baking furnace of this invention. It is explanatory drawing which shows the conventional continuous baking furnace roughly.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Continuous baking furnace 2 Furnace body 2a Furnace body side wall 3 Conveying means (roller conveyor)
3a Roller 4 Partition means (partition plate)
5 Introducing pipe 6 Exhaust pipe 7 Flat plate 8 Bowl 10 Reactive gas recovery pipe 10a Suction hole 11 Reactive gas supply pipe 11a Ejection hole H heater G Reactive gas G1 Reactive gas R area W Firing material

Claims (3)

A furnace body having a carry-in port and a carry-out port communicating with the carry-in port in the furnace body;
A transport means for transporting an object to be fired or a container containing the object to be fired from a carry-in port to a carry-out port;
A plurality of heating means provided in the furnace body;
An introduction pipe provided in the furnace body on the carry-out side, for introducing the reaction gas into the furnace body;
An exhaust pipe provided in the furnace body on the carry-in side, for exhausting the gas in the furnace body to the outside of the furnace body;
In the region where the reaction product gas is generated by the reaction between the material to be fired and the reaction gas, the inner wall surface of the furnace body side wall is provided along the longitudinal direction of the furnace body, and has a plurality of suction holes in the longitudinal direction of the outer peripheral surface. A reaction gas recovery pipe for exhausting the reaction gas and the reaction product gas out of the furnace body through the suction hole;
With
A continuous firing furnace, wherein the reaction gas recovery pipe is arranged at a height within a range from an upper surface of the object to be fired to a heating means provided above the conveying means.   The continuous firing furnace according to claim 1, wherein the reaction gas recovery pipe is provided on each of the inner wall surfaces of the left and right furnace body side walls.   The continuous firing furnace according to claim 1, wherein a reaction gas supply pipe for spraying a reaction gas downward is provided on an upper portion of the furnace body.

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