JPH03187966A - Dry-baking combination device for manufacturing ceramic product - Google Patents

Abstract

PURPOSE: To arrange a drying furnace and a baking furnace adjacent to each other in a single continuous furnace by splitting a tunnel type continuous furnace in which a circulation track for a truck is provided in the liquid and the airtightness is achieved into the drying furnace and the baking furnace by an excellently dividing means, and fixing a dry air circulating and heating means on the former furnace.

CONSTITUTION: A totally airtight continuous furnace is used in which at least one door P₁ and at least one door P₂ are provided on an entrance and an exit respectively, and a truck 1 provided with a skirt immersed in the liquid is circulated by the track immersed in a groove filled with the liquid inside. The continuous furnace is split into a drying furnace S and a baking furnace C by an airtight intermediate zone 1 or a guillotine type door P₃, and excellent airtightness is achieved between the furnaces. The humid air is taken out of the furnace by devices 5 arranged along the length of the drying furnace S, re-heated, and re-charged into the furnace. Ceramic products stacked on the truck 1 are dried and baked in the single continuous furnace by the devices.

COPYRIGHT: (C)1991,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to equipment for the production of ceramic products.

BACKGROUND OF THE INVENTION These products are formed by molding or extrusion, starting from wet clay or a mixture of clays, dried and then fired at high temperatures.

French Patent No. 356, registered June 27, 1905.
No. 838 describes an installation with a continuous tunnel. Inside this tunnel, trolleys with products circulate on suitable sliding tracks, which are dried and then fired in a furnace installation.

Problem to be Solved by the Invention However, the technical requirements for drying and calcination are so different that it has not been possible so far to economically and reliably apply the equipment described in Patent No. 356.839. Met.

In fact, desiccation occurs at relatively low temperatures (approximately 1
1k of water discharged at 20°C to 140°C (35°C at outlet)
Firing requires only a small air flow rate at very high temperatures (approximately 1.200° C.), whereas calcination requires a large air flow rate per gram.

As a result of this incompatibility, to date drying and calcination have always been carried out in separate equipment. Firing takes place in a tunnel furnace, into which fresh air and fuel are injected and burned to raise the temperature in the furnace above the firing temperature. Such combustion causes the release of carbon dioxide gas and the heating of toxic gas products, which mainly contain sulfur, chlorine and fluorinated substances. These somewhat contaminated combustion gases go to a heat exchanger, through which a stream of fresh air from the outside passes. The air thus reaches a temperature of approximately 120-140°C. This fresh air is reheated and sent to a second oven called a drying oven. Here, the shaped product, which remains wet, is dried.

Once these products are dry, they are sent to a kiln.

The somewhat polluted high temperature gas coming from the kiln, not only is its temperature too high and the flow rate is insufficient, but also the various gases introduced react with the wet clay of the product, causing efflorescence phenomenon. Therefore, it should be noted that it cannot be sent directly to the drying oven.

The above means that the technology described in the 1905 patent is not practical.

The present invention aims to achieve drying and calcination in a single continuous oven, something that has not been achieved to date.

SUMMARY OF THE INVENTION The object of the invention is a drying and firing device for ceramic products in the form of a tunnel furnace, comprising a continuous furnace divided into two parts by a gas-tight compartment, the first part of which is used as a drying oven, and a second part is used as a firing oven,
At least one door is provided at the end of the drying oven, and at least one door is provided at the outlet of the firing oven, so that the circulation track inside this single oven is immersed in a liquid-filled groove, and each carriage is With a peripheral skirt immersed in liquid, the bases of which are immersed in said liquid when the inlet and outlet doors are also closed, providing airtightness between the drying and baking areas with respect to each other and to the outside. The apparatus is characterized in that the drying area is provided with dry air recirculation means and reheating means.

The present invention also aims at the following configuration.

- Tightness between the two parts of the furnace is obtained by an intermediate compartment with pressure control and regulation means.

- Airtightness between the two parts of the furnace is provided by the guillotine grand door which, when in the closed position, is in airtight contact with the surface of the platform of the trolley.

- The relative lengths of the drying and calcination zones are proportional to the time of each operation (drying or calcination), and these times are determined by the characteristics of the raw materials.

A lock chamber with two doors is provided at the exit of one firing and/or the exit of the drying oven, and the distance between the two doors is longer than the length of the cart.

Drying air recirculation and reheating is perpendicular to the furnace;
a downwardly open suction channel, the suction channel leading to a ventilation cylinder, the delivery conduit of the ventilation cylinder being equipped with heating means, such as a burner, and leading to a slope parallel to the suction channel, the slope being A blower nozzle is provided for speed setting.

Advancement of the carriage in the drying oven-calcination oven combination takes place in pitches, the pitches being the length of the carriage or the length of the load;
or a perfect submultiple thereof, the products are arranged in equidistantly stacked supports (or gussets);
The center distance is equal to the length of the trolley, or a submultiple thereof, and the air recirculation and reheating means are provided with a space whose suction and delivery separate, at each stop, two gazettes or stacks of cargo. They are distributed so that both are located at right angles, and the length of the space is several decimeters.

The length of the intermediate section (1) is approximately equal to the length of the truck.

The product is protected by a ceramic support (or gusset) with perforated horizontal members that securely support the product.
Stacked on a trolley without touching each other, the horizontal members are provided with irregularities to secure the products and prevent deformation, and with lateral flanks perpendicular to the horizontal members.

BRIEF DESCRIPTION OF THE DRAWINGS Examples of the invention will be presented below with reference to the accompanying drawings, from which the inherent advantages of the invention will become clear.

NU1U When looking at the attached drawings, it can be seen that in the illustrated embodiment, the drying furnace S and the firing furnace C form a straight line and exist on an extension of each other. Although this configuration is not restrictive, such a configuration is desirable due to its manufacturing advantages.

The drying oven S is equipped with at least one door P1, which is opened when loading the trolley 1 carrying the raw product and closed after loading. The firing furnace C is equipped with an exit door P2 (in this case, a lock chamber for improving airtightness and reducing calorie loss).

Inside this installation, the products to be dried and baked are circulated on a trolley 1. On the trolley I, the products are distributed in stacks 2 using ceramic gussets (FIG. 2). The advance of the carriages is one pitch at a time, where one pitch is equal to the center distance between carriages or a simple divisor thereof, or the length of one stack of gussets.

The gusset consists of a perforated horizontal member 3 that reliably supports the product and, in some cases, a fixing unevenness (not shown) to prevent product deformation, and a structure that allows products to be stacked without touching each other. and has vertical flanks that allow for vertical transmission of loads.

In this way, the products pass successively through the drying and calcining ovens without the need for intermediate conveyance, and their stacking provides support for the raw or unprocessed products (without product-to-product contact and without deformation). This is achieved by simultaneously satisfying the conditions suitable for the prevention (measures that can prevent this) and the support of the dry product to be baked (temperature resistance, density of the stack, load drop on the stack, air circulation).

In order to implement this new technology, according to the invention, the drying oven and the calcining oven are very air-tight, this air-tightness means are the same in both ovens, and the whole installation has a continuous air-tight container. formation and therefore the pressure in each area must be tightly controlled.

When dry air at 20℃ reaches 85% humidity, air 1
Assuming that 12.2 g of water can be filled per kg, at 90°C and 85% humidity, 90 g per kg of air can be filled.
It must be noted that 0g is filled and at 120°C 3.5kg of air is filled. As a result, the tile after molding has a humidity of about 20%, that is, it contains 200 g of water per 1 kg of air, and therefore the temperature is 45°C.
, when air is discharged from a drying oven with a humidity of approximately 80%, 4 m3 of air is required per 1 kg of tiles. In the kiln, approximately 1.5
For a firing air flow rate of 00 m', water 60-100
A pressure of mm must be maintained. On the contrary,
In the drying oven, 3,500 m3 of air must be circulated at the suction 12 inlet at a pressure of approximately 40-5 Qmm per ton of product to be fired. Therefore, roughly speaking, it can be seen that the pressure is three times greater in the firing section than in the drying section, and the flow rate is three times greater in the drying section than in the firing section.

It is not possible to have the drying oven and the calcining oven next to each other in one continuous oven, unless special measures are taken to better differentiate the drying and baking operations.

Stacking the products to be processed on a gusset as shown in Figure 2 eliminates all transport work from one furnace to another, but stacking as shown in Figure 3 Obstructs good air circulation. This means that the drying air pressure in the drying oven according to the invention is significantly higher than the air pressure in the individual drying equipment.

Moreover, depending on the composition of the raw materials used, the drying and calcination cycle times vary greatly.

As a result of the above constraints, in order for a drying oven and a firing oven to function in combination, it is necessary to a) achieve good airtightness of all parts of the combined oven, and b) achieve good airtightness between the two parts of the oven. c) determine the respective length of drying and baking according to the time of circulation, and d) ensure that the drying air is not saturated, as this would result in loss of drying capacity. It is necessary to do so.

In order to satisfy condition a), inside the continuous furnace, the liquid 21
The rail 2 on which the ζ trolley l circulates at the bottom of the groove 22 filled with
3 is installed along the periphery of each trolley, as described in Japanese Patent Application No. 2003-12-12, to prevent air circulation under the platform of the trolley 1. Furthermore, each end of the continuous furnace,
In other words, at least 1
Install two doors P1 (drying) and P2 (firing). When the door is closed, these bases have liquid-filled grooves 22.
3 4 immersed in it. Therefore, the continuous equipment consisting of the drying furnace S and the firing furnace C is completely airtight.

Furthermore, it would be advantageous to improve the airtightness by installing double doors, forming a lock chamber, instead of just one door P1, P2. Furthermore, the distance between the two doors is
Make the distance slightly longer than the length of the trolley.

To fulfill condition b), between furnace S and furnace C either an intermediate zone 11 or a large guillotine door similar to doors P1 and P2 is used.

As is known, the firing furnace C includes air introduction means 13 under pressure.
, a fuel injection means 14, and a combustion material exhaust pipe. Furthermore, the drying oven S includes means 16 for introducing high temperature air under pressure,
A discharge pipe 17 is provided.

If intermediate zone I is used, it is provided with a pressure pickup 18.19 for controlling the air pressure at the ends of this installation (at the outlet of furnace S and at the intake of furnace C), preferably automatic means for controlling these pressure adjustments. be prepared for. For example, discharge tube 1
5 and a ventilation tube 16 that is pressurized when introducing air. 18.Adjusting the pressure at 19 means that the pressure at 19 is 1
The pressure should be equal to or higher than that at 8. 1
When the pressures at 8 and 19 are equal, there is no air flow between furnaces C and S, so section 3 is a dead area with respect to air circulation.

The combustion material from the furnace C does not pass through the furnace S, and the combustion material from the furnace S also does not pass into the furnace C, despite the absence of a door and the continuity of the space between the furnaces.

Furthermore, instead of the intermediate section I, a large guillotine door P3 placed between the furnace S and the furnace C can be simply used. In this case, it must be ensured that the large guillotine door can be lowered between the two carriages l and is supported on the upper wall of the platform of the carriage below the door. This means that the distance between the drying oven entrance and this door is an exact multiple of the length of the ridge overlap of the cart load or gazette.

In fact, the advancement through the installation takes place pitch by pitch, each pitch being at least equal to the length of the load on the trolley, and the movement is provided by transmitting a thrust to the trolley passing through the drying oven. This truck will push all the other trucks that come into contact with each other. This also means that the distance between the loads on the platform 56 is greater than the thickness of the door.

In order to meet condition C), the respective cycle times of drying and firing must be determined in each case depending on the composition of the clay or clay mixture used. Furthermore, since the cart moves at the same speed in both the drying furnace and the firing furnace, it is necessary to give each furnace a length proportional to the cycle time of drying and firing.

In order to meet condition d), the drying air must be periodically recirculated to reduce its relative humidity so as to restore its drying capacity.

Reconditioning of the drying air is realized according to the invention by devices 5 distributed along the length of the drying oven S. These devices remove humid air from the furnace, reheat it, and then reinject it into the furnace.

An embodiment of the device 5 is shown in FIGS. 4 and 5.

It is perpendicular to the furnace and open towards the bottom.
It is formed from a channel 6 forming an inlet in the form of a gutter or an inverted water trough. Channel 6 communicates with ventilation tube 7 via line 8 .

The air sucked in by the ventilation tube 7 is sent out through the conduit 9. The conduit 9 is provided with heating means 10 towards a slope 11 with a blowing nozzle 12 for setting the air velocity.

In the illustrated embodiment, the sloped surface 11 is coaxial with the channel 6, but parallel and adjacent, or
and stack 2 may be parallel with a spacing close to the center distance between them.

The invention constitutes a technical modification and, despite the increased investment and expense of using individual ceramic gussets, its advantages are significant because it at least prevents contact between the products. In practice, ceramic supports are expensive, brittle, and have a short lifetime. Therefore, in order to minimize the cost of the support, it is natural to use a support made of low-cost materials such as wood or plastic for drying, and for baking, it is natural to use a support made of low-cost materials such as wood or plastic. Ceramic supports having sufficient hardness to be stacked and placed in contact with each other so that sets or large quantities of products can be handled at once were envisioned.

Contrary to these data, in the installation according to the invention the ceramic support is multiplied (multiplying factor 10 ~ 15)
Therefore, the cost of the equipment in which the supports are introduced and the transportation cost (because the transportation involves a much larger number of fragile supports) are increased.

The combination according to the invention, in which the firing support has the characteristics of a drying support and the stack has the characteristics of a stack of firing supports, makes it possible to omit transportation between the drying oven and the firing oven, and at the same time The circulation time can be reduced to 6 hours for drying and 9 hours for baking.

This significant reduction in circulation time is due to the fact that the drying air flow rate is much lower than before, which is compensated for by systematic reheating along the dryer. The temperature of the withdrawn air is lower than for firing (40 °C), the thermal inertia of the stacking mode is much smaller, and the volume of the gusset is 6
7 dm" per kg of weight. Also, by using a very airtight furnace, the pressure can be suppressed,
The amount of air required for processing the product can be reduced.

In conventional kilns, the pressure is about 15-25 mm of water on intake air and the air consumption is about 3-4 tons per ton of product processed. In contrast, the equipment according to the invention
Functions under pressure of 100 mm water column, air consumption is 1
1.5 tons per ton.

The increased productivity and energy savings achieved in this way significantly compensate for the additional costs of storing and consuming ceramic supports.

Another advantage of the present invention is that contamination can be significantly reduced because the air flow rate used is reduced.

Furthermore, the present invention makes it possible to carry out things that have hitherto been difficult, especially the firing of overglazed products and more rational flushing.

In fact, when firing products coated with top coat, it is very important to prevent contact between the products that would cause defects in the top coat.

90 In the present invention, drying and calcination are carried out without intermediate transport, using stacking means on supports that prevent contact between the products, so that no additional measures are required for cutting, and after the product is formed. If it is not a top coat, there is a risk of deterioration of the top coat (products coated with a top coat can be manufactured).

Furthermore, since the products are not in contact with each other, a sufficient flushing effect can be obtained without requiring any special configuration.

The present invention can be modified and adjusted depending on the shape and nature of the product to be dried and baked. The length of each furnace, the length of circulation, the use of combustion material for drying, the number of stacks per trolley, the number of products per gusset, and the shape of the gusset can vary from case to case. .

The gussets shown in FIG. 2 can also be designed as individual supports, for example in the case of shaped roof tiles, but
Gazettes can also be designed to support multiple products, as shown in FIG. The main features of the invention are that these products are arranged without contacting each other (suitably fixed and supported on a perforated horizontal member 3);
The flanks 4 on both sides also allow for stacking of the gussets, lowering the load, and have mechanical resistance to compression.

In the above description, the division between the drying furnace S and the firing furnace C is obtained by the intermediate section (2) or the door P3. Door P3
Although it is simpler to use the drying furnace S, there is a risk that combustion gas containing contaminated gas may enter the drying oven S the moment the door is opened. Therefore, two partitioning means are used at the same time, that is, an intermediate partition (■) is provided, and the door P3 is placed in the center of this partition (■).
It is clear that it would be beneficial to have one installed.

The separation between the drying oven S and the firing oven C can also be achieved by completely stopping the introduction means I3 and 16 during the advance of the load. This time is sufficiently short compared to the overall processing time.

[Brief explanation of drawings]

1 is a schematic side elevational view of a drying-calcination furnace installation according to the invention; FIG. 2 is a schematic projection of a gusset support; and FIG. 4 is a schematic projection view showing the stacking of products on a trolley; FIG. 4 is a sectional view taken along the vertical line AA in FIG. 1 of additional means for recirculating and reheating dry air; , FIG. 5 is a partial view of the air reconditioning device shown in FIG. 4 viewed from above, FIG. 6 shows the gazette with the product on it, and FIG. It is a sectional view of the drying oven along. (Main reference numbers) S...Drying oven, C...Calcining oven, Pl, P2, P3...Door, l...Dolly, 2...Stacking, 3...Horizontal member, 4...Frank, 5...・Air reconditioning device, 6. Channel, 7. Ventilation pipe, 8. Pipe line,
9. Conduit, 10. Heating means, 11. Slope, 12. Blow nozzle, 13.16. Air introduction means, 14. Fuel injection means, 15.17. Discharge pipe, 18.19.・Pressure big up, 20..Skirt, 21..Liquid, 22..Groove,
23...Rail 3 4 (Voluntary) Handbook 1 Ho Seisho January 2S, 1990

Claims (10)

[Claims] (1) A drying and firing device for ceramic products in the form of a tunnel furnace, comprising a continuous furnace divided into two parts by a gas-tight compartment (I, P3), the first part of which is a drying furnace (S). ),
The second part constitutes a kiln (C), comprising at least one door (P1) at the inlet of the drying kiln (S) and at least one door (P2) at the outlet of the kiln; A circulation track (23) inside one furnace is a groove (21) filled with liquid (21).
22), and each trolley (1) is immersed in the liquid (21).
) with a peripheral skirt (20) immersed in the entrance door (P
1) and the outlet door (P2) are also immersed in the liquid with their bases closed, and the drying oven (S) is equipped with means for recirculating the drying air and means for reheating. (2) The airtight section between the drying furnace (S) and the firing furnace (C) is
2. The device according to claim 1, characterized in that it is obtained by an intermediate compartment (I) with means (18, 19) for controlling and regulating the pressure occupying the furnace (S) and the furnace (C). (3) The airtight section between the drying furnace (S) and the firing furnace (C) is
2. Device according to claim 1, characterized in that it is obtained by a guillotine door (P3) which in the closed state is in airtight contact with the surface of the platform of the trolley (1). 4. Device according to claim 1, characterized in that said hermetic partition is realized by simultaneously using the means according to claim 1 and the means according to claim 3. (5) The apparatus according to any one of claims 1 to 4, characterized in that the lengths of the drying oven (S) and the firing oven (C) are proportional to the cycle time of drying and firing, respectively. (6) Inlet of drying furnace (S) and/or firing furnace (C)
6. Device according to claim 1, characterized in that the exit of the device comprises a locking chamber with two doors, the distance between the two doors being greater than the length of the carriage (1). (7) The means for recirculating and reheating the dry air comprises an inlet channel (8) perpendicular to the furnace (S) and open downwards, which channel leads into the ventilator (7) and which The inlet conduit (9) of the cylinder is equipped with heating means, such as a burner (10), and opens into a slope (11) parallel to the intake channel;
7. Device according to any one of the preceding claims, characterized in that the slope is provided with a speed-setting air nozzle (12). (8) The carriage in the drying oven (S)-firing oven (C) combination device is moved forward in pitches, and the pitch is determined by the carriage (1
) or the length of the product stack, or an exact submultiple thereof, and the product is equal to the length of the stack of equally spaced supports (
air recirculation and reheating means, the suction and delivery of which are
8. According to any one of claims 1 to 7, characterized in that they are both located at right angles to a space dividing the stack of two gussets, the length of which space being several decimeters. Device. 9. Device according to claim 3, characterized in that the length of the intermediate section (I) is approximately equal to the length of the carriage. (10) The products can be placed on the trolley (1) without contacting each other by means of a ceramic support (or gusset) with perforated horizontal members (3) that securely support the products.
10. Stacked on top of each other, said horizontal member comprises an indentation for fixing the product and preventing deformation, and lateral flanks perpendicular to said horizontal member. equipment.