RU2045725C1 - Method and device for roasting ceramic articles - Google Patents

Abstract

FIELD: firing kilns for roasting ceramic articles. SUBSTANCE: double- chamber kiln has three parallel walls 1 (two lateral walls and one intermediate wall) connected by roof 2. Mounted on lateral walls are gas burners 7 connected to distributing combs 9 through mixing chamber 19. Combs are made in recesses 8 of lateral walls and are provided with nozzles 13 located coaxially relative to channels 11 of brick charge 12. Located in intermediate wall is central smoke collector 14 with holes 15 for taking waste kiln gases. Method of roasting ceramic articles consists in feeding heat-transfer agent from gas burners and smoke recirculant under pressure through nozzles 13 of distributing combs 9 and directing it to channels 11 of brick charge; waste gases flow to top portion of smoke collector 14 and through holes 16 for recirculation to mixing chamber 19 and to bottom portion of smoke collector through passages 20 to furnace flue 22. EFFECT: enhanced reliability. 3 cl, 5 dwg

Description

 The invention relates to heat engineering, and in particular to furnaces for firing ceramic products.

Known continuous kilns for firing clay bricks with a more uniform heating of the products and reducing the occupied area. The furnace is made in the form of a two-three-tier tunnel, on each tier of which trolleys with a brick, laid on metal gratings, move along the rails, ensuring the passage of the coolant from the bottom up through the bricks. After heating on the first tier, the trolleys rise to the second for firing, then lower to the lower for cooling. Waste heat from the firing zone enters the preheating zone. In such furnaces, the principle of the passage of heat through the brick cage and its more economical use is used. However, they are complex in design, metal consuming and unreliable in [1]
The closest in technical essence is a kiln for firing ceramic products, including two chambers, separated by an intermediate wall with a channel for exhaust gases placed in it, under the side walls with burners, screens separated from the working space. The uniformity of temperature over the entire volume of the furnace is ensured by the fact that niches are made in the side walls, and the burners are installed coaxially in the narrowed places of the niches. Although in this furnace, due to the turbulence of the movement of hot gases, a more uniform heating is ensured over the volume of the furnace, but uniformity of heating over the volume of brick cages is also not achieved, which affects the quality of the products. In addition, this furnace is inefficient due to the length of the temperature equalization cycle for the volume of brick stacking and the inability to load large batches of products, since in this case there is no guarantee of reliable operation of the lifting mechanisms and the strength of the hearth [2]
The firing method used in the known furnace is as follows. The torch from the burners is directed along the walls in opposite directions. The coolant enters through the openings of the screens and from the end walls of the furnace into the chamber, washes the products, and then part of the exhaust gases of the first chamber through the openings and flues in the hearth masonry enters the second chamber. Exhaust flue gases enter the chimneys located in the walls and roof of the furnace, giving off heat to the latter, and then to the exhaust. Cooling is done by atmospheric air with extinguished burners. The disadvantage of this method is the uneven heating in the volume of the charge and low efficiency of the furnace.

 The aim of the invention is to improve the quality of products by ensuring a uniform firing temperature throughout the volume of the brick cages and reducing firing time.

 In the proposed method of firing ceramic products, including the flow of coolant to the charge of products, channels are formed in the charge, and the exhaust gases are divided into two streams, one of which is mixed with the coolant and fed into the charge channels, and the other is removed from the furnace with subsequent disposal.

 In a kiln for firing ceramic products, including two chambers separated by an intermediate wall with a channel for exhaust gases placed in it, burner devices located in the side walls of the chambers, burner devices are made with a distribution comb with nozzles directed into the channels in the cage, and with a mixing a chamber placed in front of the distribution comb and connected by a pipeline to the exhaust gas channel.

 In FIG. 1 shows the proposed furnace, cross section; figure 2 is the same, a top view; figure 3 is the same, a cross section along the axis of the Central smoke collector; figure 4 comb and cage of brick in the context; figure 5 cage brick.

 The furnace is made of two-chamber and includes three parallel walls 1, of which two side and one intermediate, connected by arches 2. The ends of the chambers are blocked by walls 3 on one side and sealed doors 4 on the other side. The tightness of each chamber 5 is achieved by installing sand shutters 6. On the side walls 1 are installed high-speed burners 7 located in two rows in height. In front of the burners in the niches 8, distribution combs 9 are installed with nozzles 10 located opposite the channels 11 of the brick 12. In nozzles 10 there are nozzles 13 with the possibility of centering them relative to the channels 11 of the brick. In the intermediate wall 1 there is a central smoke collector 14 with openings 15 for the removal of furnace gases from the working space of the furnace. In the upper part of the smoke collector 14, holes 16 are made for the intake of furnace gases for recirculation using a high-pressure heat fan 17 and pipelines 18 supplying smoke to the mixing chamber 19 located between the burner 7 and the comb 9. At the bottom of the smoke collector 14 there are passages 20 for removal furnace gases through the pipe 21 in the burs of the furnace 22. The brick 12 is mounted on a substrate 23 made of hollow refractory, which is fixedly mounted on a trolley 24 moving along rails 25. To improve For heating the brick cages, the side and intermediate walls 1 are made with vertical 26 and horizontal 27 clamps.

 The furnace operates as follows. Four trolleys 24, on each of which 4 cages of brick 12 are located, are rolled into the furnace, two trolleys are placed in each chamber 5. The chambers are sealed with doors 4 and sand gates 6. The burners 7 are ignited, the heat fan 17 is turned on and the brick is fired. Combustion products from burners and smoke are recirculants, and in the initial period, air from the heat fan 17 is supplied under pressure to the mixing chamber 19, where they move, and through a niche 8 they are sent to the nozzles 10 of the distribution comb 9 and then through the nozzles 13 to the channels 11 brick cages 12. The targeted flow of hot gases supplied directly to the cage and brick channels ensures uniform heating of the products throughout the volume of brick cages. In the working space of the furnace, the circulation of furnace gases is created due to the ejection that occurs at the inlet of the coolant into the channels 11 and as the coolant passes through the channels through the charge. This ensures a high level of gas permeability of the cages, which also contributes to uniform heating. The dispersion of the flow into the gaps between the cages, the furnace end walls, and trolleys is eliminated thanks to the clamps 26 and 27, which serve as plugs. The coincidence of the axes of the nozzles 13 of the comb 9 with the channels 11 of the brick cage is ensured by the fixed installation of the trolley and the fixed location of the brick cage on it, the installation of which is carried out by a machine (not shown), and also by the fact that the nozzles 13 are installed in the nozzles 10 of the comb 9 with the possibility of clear fixation relative to the longitudinal channel 11 of the brick cages 12. In this case, the cross-sectional area of the nozzles 10 is several times larger than the area of the nozzles 13. The exhaust gases are directed through openings 15 into the central smoke collector 14, from otorrhea portion is fed to the fan 17 dymoprovod recirculating furnace gases 18 to 18 dymoprovod recirculation of furnace gases to the mixing chamber 19, in other dymoprovod 21. Further in hog and 22 for disposal.

The proposed design of the furnace and a new method of firing ceramic products in comparison with the known allows to obtain a number of advantages:
the introduction of high-speed firing modes due to the forced introduction of the coolant into the cage channels and, as a result, improving the uniformity of the cage heating, reducing critical temperature differences over the cage cross-section for individual technological firing periods with a maximum temperature rise rate;
obtaining high-quality bricks with a minimum variation in quality in a batch of bricks;
simplicity of design and high reliability of the furnace;
the possibility of the most complete utilization of the heat spent on firing makes it possible to use fuel more economically. Consumption of 250 kg of standard fuel per 1000 pcs. brick is a high technical and economic indicator. Heat losses with flue gases account for 33.6% while in known chamber furnaces they account for 60-70%
the ability to create automatic lines of flexible productivity from 5 to 50 min pcs. conditional brick, which will allow, in the case of a forced decrease in the volume of brick production, to turn off part of the furnaces and work without increasing the specific fuel consumption.

Claims (2)

 1. A method of firing ceramic products by supplying a coolant to the product cage, characterized in that channels are formed in the cage and the exhaust gases are divided into two streams, one of which is mixed with the coolant and fed into the cage channels, and the other is removed from the furnace with subsequent disposal .  2. A kiln for firing ceramic products, mainly bricks, containing two chambers separated by an intermediate wall with an exhaust gas channel placed therein, burner devices located in the side walls of the chambers, characterized in that the burner devices are made with a distribution comb with nozzles directed into the channels in the cage, and with a mixing chamber placed in front of the distribution comb and connected by a pipe to the channel for exhaust gases.