RU2200922C2 - Method of burning brick and device for realization of this method - Google Patents

Abstract

FIELD: manufacture of bricks and structural ceramics. SUBSTANCE: method includes forming of brick burden by placing one article on another, thus arranging columns at clearances sufficient for free passage of heat-transfer agent. Brick burning is performed in shaft furnace whose burning channel is provided with vertical guides arranged in groups. Heat-transfer sources are located in clearances between guide passages; heat-transfer agent is supplied to clearances between laying surfaces. EFFECT: intensification of process; improved quality of articles. 14 cl, 10 dwg

Description

FIELD OF THE INVENTION
The invention relates to the building materials industry and can be used in the manufacture of bricks and some other ceramic products, namely in the firing process. The invention is applicable to all types of bricks and ceramic stones having the shape of a rectangular parallelepiped, as well as a shape close to it.

State of the art
The most widely known methods of firing bricks in ring and tunnel kilns. However, the disadvantage of such furnaces is the unevenness of firing bricks stacked, cumbersome production, heat loss, the presence of special trolleys to move the charge of products. Recently, continuous vertical furnaces have gained distribution: shaft and slot-type furnaces, with moving material and stationary technological zones. The technological process in vertical-type furnaces is directed from top to bottom, which made it possible to use the movement of products under their own weight and to exclude special vehicles for moving products through the furnace. In addition, the vertical design of the furnace made it possible to bring the heat sources closer to the products to be fired, which led to an increase in the thermal efficiency of the process and a reduction in the firing time. Thus, vertical furnaces are less material-tight, and the firing method in such furnaces is fast, more efficient and economical.

 A known method of firing ceramic products (patent for invention 2110027, RF, class F 27 B 1/00, F 27 B 9/14, publ. 04/27/1998), in which the products are sequentially fed into the furnace by a pusher from the press. The products are moved along a spiral trajectory defined by a spiral single-turn roller table from top to bottom through the heating, firing and cooling zones. The movement channel is formed by a cylindrical gap between the coaxially located walls of the furnace (internal and external). Brick is heated in the firing zone by means of gas burners located in the outer wall of the furnace.

 This method provides high productivity of the process, but requires special equipment. In addition, a brick cage, which is a product laid on top of one another on a die (i.e., bed on bed), does not provide uniform access of the coolant to the entire surface of the product, which leads to uneven firing of the product in its volume.

 A known method of heat treatment of ceramic products in a vertical furnace (patent for invention 2098384, RU, class C 04 B 33/32, F 27 B1 / 00, publ. 10.12.1997), comprising supplying the heat carrier to the cage in the horizontal direction with several formed in layers and directed towards each other by streams converging in the center of the cage, moving one step up and then diverging from the center in opposite directions. In this case, the cradling of products is carried out in such a way that in it there are alternations in the height of the rows of bricks installed on the spoon face and on the die. The pattern of the brick cages installed on the spoon edge does not change and is repeated through a row in height. It provides through channels for the passage of the coolant. The setting of the rows of brick laid on the die is changing. In the first embodiment, there is one channel for the passage of the coolant, and it passes through the center of the row, dividing the row into two equal parts. In the second embodiment, two side channels are formed, which are located between the cage and the opposite walls of the furnace, to which the furnaces adjoin. The aforementioned layer-by-layer motion of the coolant flows through the channels formed by a certain installation of products in rows is repeated many times, as well as the alternation of rows in the cage. This ensures a uniform distribution of coolant and air for cooling products along the height of the stack. The loading of raw brick is done manually or by a machine-garden. The movement of the cages can be continuous or periodic after a certain period of time. The entire brick cage is held and moved by a special device.

 The advantage of the above invention is to improve the quality of products by ensuring uniform firing, however, the cage has a rather complex structure and requires a special device to move.

 Closest to the claimed invention is a method of firing wall ceramic products in a vertical furnace (patent for invention 2031340, Russian Federation, class F 27 1/00, publ. March 20, 1995, bull. 8), which is a technological cycle including loading products in a layer-by-layer loading mechanism on top of the furnace, synchronizing one row down the entire cage along the firing channel and layer-by-layer batch unloading of finished products from the bottom of the case. Cage products made in the form of columns with a section of 250x250. When firing products in nozzles, fuel is burned, and through gas distribution devices, the resulting coolant leaves the gaps and washes the charge.

 The design of the charge plays a decisive role both in the process of heat exchange between the products and the gas stream, and in the distribution of heat in the brick body. Uneven heating of the product, especially in conditions of high-speed firing, leads to the appearance of warpage and deformation of the product, which means a decrease in the quality of the finished product. Therefore, the cage should provide minimal resistance to the movement of gases and air, contribute to the most uniform distribution of fire over the cross section of the furnace channel, be stable and at the same time convenient for loading and unloading bricks. Perfect in the heat engineering sense is the cage, in which the products are installed so that the maximum possible surface area of the product is freely and evenly washed by the coolant.

 In the decision according to patent 2031340, each pillar of the charge is formed by rows of bricks mounted on top of each other with the formation of a cross section of 250x250, i.e. several products in each row of the column. In this embodiment, the design of the cages there are labyrinth-like gaps for the passage of the coolant, which makes it difficult for the coolant to access the products. As a result, the firing intensity decreases, the time required for sufficient heating of the products increases, and, in addition, uniform heating of the products inside the cage is not ensured.

 A known vertical furnace for firing ceramic products (patent for invention 2023965, RF, class F 27 B 1/00, publ. 11/30/1994, bull. 22), containing vertical firing channels formed by vertical walls of heat-resistant material, mechanisms loading and unloading located on the frame of the furnace, respectively, above the inlet and under the outlet sections of the calcining channels. In the wall gaps between adjacent sections of the furnace are burner devices and channels for supplying air for burning and cooling products, as well as channels for removing heated air and flue gases. The sealing of the input section of the calcining channel and the separation of the calcining and cooling zones are carried out by spring-loaded rotary valves. Hydraulic cylinders, rotary clamps and a conveyor belt are used as elements of the mechanism for unloading finished ceramic products. The furnace belongs to vertical slotted furnaces and has all the advantages of slotted furnaces given above. In addition, an efficient radiation-convective firing regime is implemented in the furnace, in which the products are heated by a stream of flue gases and by thermal radiation of microflares and walls of burner devices.

 However, the furnace consists of several sections, containing one vertical firing channel and separated by walls made of heat-resistant material, which indicates its high material consumption. The design of the cage in this furnace is a column of products arranged in order, which implies the presence of small gaps between the products in the cage, which, in turn, affects the uniformity of heating of the products, and hence the quality of the products obtained.

 As a prototype of the claimed device adopted a vertical furnace (patent for invention 2031340, RF, class F 27 B 1/00, publ. 03.20.1995, bull. 8), containing a vertical rectangular housing with zones of heating, firing and cooling horizontal partitions with windows, loading and unloading devices, gas supply and exhaust ducts, product cages, which are placed with a gap in the windows of the partitions and are a collection of posts with a section of 250x250 mm. To improve the regulation of the firing process, the furnace is equipped with flowing tanks with water located in the heating and cooling zone and connected to each other, and the gas distribution devices of the furnace are made in the form of pieces of rectangular pipes laid by mutually intersecting horizontal rows covering the product cage with gaps at the intersection for exit coolant.

 The above-mentioned structural features of the furnace allow to some extent improve the uniformity of firing, however, the arrangement of products in the cage in the form of columns 250x250 in size limits the access of the coolant to the surface of the products inside the column.

The essence of the claimed invention
The claimed invention solves the problem of improving the quality of manufactured products by ensuring uniform firing, while intensifying the firing process.

 The problem is solved in that in the method of firing bricks in a shaft furnace, including loading products from the top of the furnace body with installation on a cage, made in the form of a collection of product columns evenly distributed in the furnace volume, synchronous movement of the cage along the calcining channel, the flow of coolant into the gaps between the columns and unloading the bottom of the furnace of finished products, according to the claimed invention, each cage column is formed by sequential installation of one product on another with the formation of the die surfaces of the products Vuh opposing pole faces arranged poles manufacturing roaster channel to form a gap between said pole faces, sufficient for free movement of the coolant, and the coolant flow is performed in the gaps perpendicular to the faces formed by surfaces plashkovymi products.

 The technical result, namely the uniformity of firing products, is achieved by increasing the surface, free for uniform access to the coolant. Such an increase was made possible by the proposed design of the cage products. In the inventive method, each brick is set in such a way that the product faces are the largest in surface area, i.e. dies turn out to be freely washed with coolant. In this case, in one specific case of the implementation of the proposed method, the bricks are installed "by pushing on a stick", and in another - "spoon on a spoon." The bump is the smallest facet of the brick, therefore, it is preferable to implement the method with the installation of products "poke on the poke." In any case, the implementation of the method is an indispensable condition for the formation of two opposite faces of the column with the die surfaces of the products, therefore, the die faces of the product that have the largest surface area, in any case, the formation of cage posts remain free and open for coolant access.

 Gaps are maintained between the product columns, and the gaps between the faces of adjacent columns formed by the die surfaces of the products are from 10 to 40 mm, and the gaps between the faces perpendicular to the above are from 20 to 80 mm. The gaps are used to ensure free access of the coolant to the products. However, when the gaps between the faces formed by the dice surfaces of the bricks are more than 40 mm and the size is greater than 80 mm for the gaps between the faces perpendicular to the aforementioned, there is not enough temperature stress required for firing. With the size of the gaps between the die surfaces of the bricks less than 10 mm, it is impossible to place the clamping elements of the locking mechanism in them to hold the pillars of the products during unloading. The size of the gaps between the faces perpendicular to the die surfaces of the products, less than 20 mm, will not allow them to place sources of thermal energy of firing and gas exhaust devices.

 Upon completion of the movement of the product columns in the firing channel by an amount equal to the size of the product along the height of the column, the products are unloaded. Unloading is carried out in order, and pre-fixation of each product in a row above in relation to the unloaded.

 This goal is also achieved by the fact that the shaft kiln for firing bricks, containing a firing channel, a loading device installed above the upper opening of the furnace, an unloading device located under the lower opening of the furnace, including a fixing mechanism for the charge and a mechanism for reducing and unloading products, sources of thermal energy for firing, gas exhaust devices located in the calcining channel according to the claimed invention, the furnace is equipped with vertical guides mounted in the calcining channel arranged in groups of in the form of a set of guide channels spaced apart from one another, freely spanning columns from successively mounted one on top of another with the formation of two opposite faces of the product column with the die surfaces, while the vertical guides adjacent to the mentioned column faces are spaced apart relative to the others with the formation of gaps between the columns products sufficient for the free movement of the coolant flow, and heat sources of time escheny in the gaps that are perpendicular to the said.

 The introduction of vertical guides into the device, dividing the working volume of the furnace into a set of vertical guide channels, allows you to organize the passage of fired products sequentially one after another from top to bottom along the firing channel. With this solution, the dimensions of the channels are as close as possible to the dimensions of the transported column of products, but do not impede the movement of products. Vertical guides can be made in the form of vertical rods of heat-resistant alloy. The rods are combined into groups forming a guide channel, and are fixed to each other by means of horizontal brackets, covering the rods on one or the other side of the channel with alternating height of the channel of the covered sides. The brackets have only a point connection with the guides, made, for example, by a welding method, and the welded rods are also alternated. The absence of a rigid connection ensures the mobility of the system, eliminates distortions and deformations possible under high-temperature firing conditions. Vertical guides can be made of thin strips of heat-resistant material, however, in any embodiment, the thickness of the guides should be significantly less than the size of the fired products. This is a necessary condition to ensure free circulation of the coolant between the products in the cage.

 Thus, the listed set of essential features allows to obtain a technical result similar to the method, namely, to ensure uniform firing of products in the furnace. Obtaining the same technical result indicates the unity of the inventive concept that connects the claimed method and device.

 The guide channels for moving the fired products are spaced with each other with the formation of gaps. The gaps between the sides of the guide channels corresponding to the faces of the cage posts formed by the die surfaces of the products are from 10 to 40 mm, and the gaps perpendicular to them are from 20 to 80 mm. The gaps correspond to the conditions for the implementation of the firing method and are explained above. The upper limit of the intervals is due to technological reasons, namely the fact that with large gaps, sufficient temperature stress will not be created to ensure the necessary heating of the products. The lower limits are due to technical reasons, namely the fact that in the gaps place sources of thermal energy, gas exhaust devices and clamping elements of the locking mechanism.

 The shaft furnace contains sources of thermal energy for firing, which can be made in the form of diffusion beam burners located in the firing channel and installed in such a way that the location of the coolant outlet openings coincides with the location of the gaps between the faces of the charge posts formed by the die surfaces of the products. Thus, the coolant flows are strictly oriented and directed into the gaps between the faces of the cage posts formed by the die surfaces of the products. This technical solution allows to increase thermal efficiency and efficiency of the firing process due to the maximum approximation of heat sources to fired products, to increase the intensity of the process due to the strict orientation of the coolant flows. To organize the coolant flows, the furnace can additionally be equipped with valves located horizontally in the gaps between the guide channels above the heat sources.

 The technology of firing using gas burners requires special channels for the removal of gas combustion products. In the furnace, gas exhaust devices are provided in the form of pipes, the pipes being carried out into the working volume of the kiln channel of the furnace and placed in the gaps between the guide channels similar to the location of gas burners. The lowering of the column of products is carried out in a step-by-step mode due to the interaction of the locking mechanism that rotates relative to the horizontal axis of the table and chain conveyors, which together form a mechanism for unloading products.

 The fixing mechanism of the charge is made in the form of a set of individual clamping elements for each column of products, which provide reliable retention of the charge in the calcining channel of the furnace during the unloading of the lower row of products.

 A rotary table mounted with the possibility of reciprocating movement vertically allows you to separate the lower unloading row of products and transfer these products to a transport means, eliminating the risk of damage to the surface of the finished products. The rotary table is equipped with slots located on the side opposite the axis of rotation of the table, and made with the possibility of passage in them of chain conveyors. Thus, the use of additional colliding means is excluded, unloaded products are laid directly on the conveyor, and then removed from the furnace zone. When performing the conveyor in the form of a chain conveyor, two threads are provided for each stack of products.

 In addition to the above technical result, which allowed to improve the quality of manufactured products, the claimed device is characterized by thermal efficiency due to the uniform distribution of heat load over the cross section and height of the furnace, thermal efficiency and the intensification of the firing process, due to the proximity of the burner devices to the fired products, and at the same time a small material consumption , simplicity and convenience of prevention and repair.

List of drawings
The invention is illustrated by drawings, which depict:
figure 1 - shaft furnace, a schematic representation;
in FIG. 2 is a diagram of a product cage with a “poke-to-poke” brick installation, a frontal isometric view showing the gaps between the product posts in the cage and the location of the guides for the product column;
in FIG. 3 - remote element I from figure 1, showing the relative position of the vertical guides and horizontal staples forming channels for the passage of products;
figure 4 is a horizontal section bB in figure 3, which shows the gaps between the guide channels;
in FIG. 5 is a side view of the cage with a schematic showing the location of gas burners and gas exhaust devices;
in FIG. 6 is a section BB of FIG. 5, which shows the distribution of coolant flows;
figure 7 - elements of the locking mechanism;
in FIG. 8 - unloading mechanism and the extreme positions of the rotary table are shown when working with a chain conveyor;
figure 9 is a top view of a chain conveyor with paged items;
figure 10 is a sketch of a brick indicating the faces.

Information confirming the possibility of carrying out the invention
The inventive method of firing bricks was implemented by the inventive device.

 The shaft brick kiln contains (see FIG. 1) a housing 1 in which the kiln channel 2 is located. A loading mechanism 3 is installed above the upper aperture of the kiln. Under the lower aperture of the furnace there is a locking mechanism 4 and a mechanism for lowering and unloading products, made in the form of a table 5 rotatable around a horizontal axis 6, mounted with the possibility of reciprocating movement vertically and interacting with a chain conveyor 7. The furnace is equipped with vertical guides 8 mounted in firing channel 2. Guides 8 are made in the form of vertical rods of heat-resistant alloy, arranged in groups by means of horizontal brackets 9 and forming a totality of one full vertical guide channels 10 for the passage of the pillars of the product. Horizontal staples 9 span the rods from one side to the other, alternating along the height of the channel of the covered sides (see FIG. 3).

 Guide channels 10 are used to organize the passage of products entering the firing. The dimensions of the guide channels are as close as possible to the dimensions of the products passing through them. The guide channels 10 form a gap between them 11 and 12 (see figure 4). The size of the gaps 12 is 75 mm and is due to the location of the sources of thermal energy of firing, made in the form of beam burners 13 diffusion type pipes 14 for exhaust flue gases and heated air, and valves 15 made in the form of profile strips and installed horizontally between the guides 8 (see Fig. 5).

 Cage products in the furnace is a collection of columns 16 (see Fig. 2). Each pillar is obtained by sequentially placing one product on another on the smallest face, i.e. "poke on the poke" (see Fig. 10).

 The burner 13 has openings 17 for the exit of the coolant (see Fig.6). The burners are installed between the guide channels, and the location of the holes 17 coincides with the location of the gaps 11 between the faces of the posts 16 cages formed by the die surfaces of the products. The size of the gaps 11 is 35 mm. The value is due, on the one hand, to technological reasons and is sufficient for the free passage of heat fluxes, on the other hand, in the gaps 11 are clamping elements 18 of the locking mechanism 4.

 The fixing mechanism 4 is made in the form of a set of elastic clamps 18, individual for each column of products (see Fig. 7), operating from a hydraulic actuator, and serves to hold the product stack posts during unloading.

 The rotary table 5 is equipped (see Fig. 8) with slots 19 located on the side opposite to the axis of rotation 6, and configured to pass chain conveyors 7 therein.

 The method of firing products in the above furnace is implemented as follows.

 With the loading mechanism 3, products prepared for firing (in our case, bricks) are installed on the upper row of posts 16 of the charge of the shaft furnace ready for operation.

 In gas burners 13, gaseous fuel is burned, and the resulting coolant through holes 17 is directed by a directed flow into the gaps 11 between the faces of the charge posts formed by the die surfaces of bricks (see Fig. 6). Due to the fact that the columns are spaced in the furnace volume with the formation of gaps 11 and 12, the coolant freely washes each column 16 of the product, thereby ensuring uniform heating of each brick. The coolant is as close as possible to the products being fired, which contributes to the firing intensity and allows to burn products without defects with high technical parameters in the shortest possible time with minimum fuel consumption. Valves 15, limiting the spread of coolant flows vertically upward and directing coolant flows in the horizontal direction between the columns 16 of the products, also contribute to the uniformity of firing.

 The flue waste resulting from combustion and heated air are captured by pipes 14 and discharged from the firing zone.

 After the technologically predetermined firing time has passed, the fixing mechanism 4 clamps the bricks of the penultimate, relatively unloaded row by means of individual clamping elements 18 and holds the posts 16 of the products. The rotary table 5, with the lower row of finished products 20 located on it, is lowered by an amount equal to the height of the product in the cage post, thereby separating the unloaded row of bricks. Then, the table 5 is rotated around the horizontal axis 6, while the unloaded products 20 are stacked directly on the conveyor 7 (see Fig. 9), passing in the slot 19 of the table 5, and then removed from the zone of the table, giving the latter the opportunity to rise in starting position. The next batch of raw brick is being loaded. Pillars 16 are unlocked. Brick cages are lowered by the size of the brick along the height of the column 16 cages. Then unloading is carried out, and the cycle repeats.

Claims (14)

 1. A method of firing bricks in a shaft furnace, including loading products on top of the furnace body with installation on a cage, made in the form of a plurality of product columns uniformly distributed in the volume of the firing channel of the furnace, synchronously moving the cages through the calcining channel, supplying coolant to the gaps between the columns and unloading from below furnaces of finished products, characterized in that each cage pillar is formed by sequential installation of one product on another with the formation of two opposite sides of the table with die surfaces of the products and, placing articles in columns roaster channel to form a gap between said pole faces, sufficient for free movement of the coolant, and the coolant flow is performed in the gaps perpendicular to the faces formed by surfaces plashkovymi products.  2. The method according to p. 1, characterized in that the products in the column of the charge are installed with a poke on the poke.  3. The method according to p. 1, characterized in that the products in the column cages set with a spoon on a spoon.  4. The method according to p. 2 or 3, characterized in that the gaps between the faces of adjacent columns formed by the die surfaces of the products are 10-40 mm, the gaps between the faces perpendicular to the aforementioned are 20-80 mm.  5. The method according to any one of paragraphs. 1-4, characterized in that the unloading of products is carried out in order at the end of the movement of the columns of products in the firing channel by an amount equal to the size of the product along the height of the column, and when unloading, each product is fixed in a row located in relation to the unloaded.  6. A shaft kiln for firing bricks, containing a firing channel, a loading device installed above the upper opening of the furnace, an unloading device located below the lower opening of the furnace, including a fixing mechanism for the charge and a mechanism for reducing and unloading products, sources of thermal energy for firing, located in the firing channel and gas exhaust devices, characterized in that the furnace is equipped with vertical guides mounted in the calcining channel, arranged in groups in the form of a set of spaced one relative to another about guide channels freely spanning columns from successively mounted one on the other with the formation of two opposite faces of the product column with the die surfaces, while the vertical guides adjacent to the mentioned column faces are spaced apart relative to the others with the formation of gaps between the product columns sufficient for free movements of the coolant flow, and sources of thermal energy are placed in the gaps perpendicular to the aforementioned.  7. The furnace according to claim 6, characterized in that the gaps between the sides of the guide channels corresponding to the faces of the cage posts formed by the die surfaces of the products are from 10 to 40 mm, and the gaps perpendicular to them are from 20 to 80 mm.  8. The furnace according to claim 6 or 7, characterized in that the vertical guides are made in the form of vertical rods of heat-resistant alloy and are grouped by horizontal brackets, covering rods on one or the other side of the channel, with alternating parties.  9. The furnace according to any one of paragraphs. 6-8, characterized in that the sources of thermal energy for firing are made in the form of beam burners of diffusion type, installed with a combination of the location of the openings for the exit of the coolant and the gaps between the faces of the cage posts formed by the die surfaces of the products.  10. The furnace according to claim 9, characterized in that the furnace is equipped with valves for organizing coolant flows located horizontally in the gaps between the guide channels above the sources of thermal energy.  11. The furnace according to any one of paragraphs. 6-10, characterized in that the gas exhaust devices are made in the form of pipes located in the gaps between the guide channels similar to heat sources.  12. The furnace according to any one of paragraphs. 6-11, characterized in that the fixing mechanism of the charge is made in the form of a set of individual clamping elements for each column of products.  13. The furnace according to any one of paragraphs. 6-12, characterized in that the mechanism for reducing and unloading products is made in the form of a table rotatable relative to the horizontal axis, mounted with the possibility of reciprocating movement vertically.  14. The furnace according to claim 13, characterized in that the rotary table is provided with slots located on the side opposite to the axis of rotation of the table and made with the possibility of passage of chain conveyors into them.

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