An energy-saving tunnel kiln that can effectively recover and utilize waste heat

Abstract

This utility model discloses an energy-saving tunnel kiln that can effectively recover and utilize waste heat, including a kiln body and a kiln car. The kiln body includes a drying zone, a preheating zone, a firing zone, and a cooling zone. A waste heat chamber with an inverted U-shaped cross-section is provided on the outer wall of the kiln body. A gas pipe and an auxiliary gas pipe are provided in the waste heat chamber. A flue gas chamber with an inverted U-shaped cross-section is provided inside the kiln body. An upper air hole communicating with the flue gas chamber is provided on the top of each zone of the kiln body. A row of connecting holes communicating with the internal space of the kiln body are provided on the flue gas chambers on both sides of the kiln body. A partition plate is horizontally provided in the flue gas chamber above the connecting holes at the positions of the drying zone, the preheating zone, and the cooling zone. The exhaust pipe on the cooling zone is connected to the air inlet pipe on the drying zone through a pipeline. A vent is provided on the partition plate between the preheating zone and the firing zone. The vent connects the flue gas chamber of the firing zone and the air inlet chamber of the preheating zone. The gas pipe and the auxiliary gas pipe are connected to the burner on the firing zone.

Description

Technical Field

[0001] This utility model relates to the field of energy-saving tunnel kiln technology, specifically to an energy-saving tunnel kiln that can effectively recover and utilize waste heat. Background Technology

[0002] A tunnel kiln is a continuous industrial kiln widely used in firing or heat treatment processes in ceramics, refractory materials, bricks and tiles, electronic components, and other fields. Its name comes from the long tunnel shape of the kiln body. A tunnel kiln consists of a preheating zone, a firing zone, and a cooling zone. The combustion equipment is located on both sides of the middle section of the tunnel kiln, forming a fixed high-temperature zone, the firing zone. The high-temperature flue gas generated by combustion flows along the tunnel towards the kiln head under the action of the chimney or induced draft fan at the front of the tunnel kiln, gradually preheating the products entering the kiln. This section constitutes the preheating zone of the tunnel kiln. At the kiln tail, cold air is blown in to cool the products in the latter part of the tunnel kiln. The residual heat is then extracted and sent to a dryer as a heat source for drying the green blanks. This section constitutes the cooling zone of the tunnel kiln. The workpieces move continuously via kiln cars or conveyor belts, sequentially passing through the preheating, firing, and cooling stages, achieving efficient and stable mass production.

[0003] Currently, tunnel kilns still face the following problems during operation: First, a large amount of heat is generated during firing, of which 70% to 80% may remain unused. This heat diffuses to the top, causing heat accumulation and wasting a significant amount of thermal energy. Second, the combustion flame of the burner is horizontally ejected, while the high-temperature flue gas rises, resulting in a higher temperature at the top than at the bottom. Existing technologies mostly address this by increasing the power or number of lower burners, which undoubtedly increases energy consumption and production costs. Therefore, it is objectively necessary to develop an energy-saving tunnel kiln that minimizes heat waste, reduces the temperature difference between the top and bottom of the kiln, and achieves better firing results while effectively recovering and utilizing waste heat. Utility Model Content

[0004] The purpose of this invention is to provide an energy-saving tunnel kiln that minimizes heat waste, reduces temperature differences between the upper and lower parts of the kiln, and achieves good firing results, while effectively recovering and utilizing waste heat.

[0005] The purpose of this utility model is achieved as follows: It includes a kiln body and a kiln car. The kiln body sequentially comprises a drying zone, a preheating zone, a firing zone, and a cooling zone. A waste heat chamber with an inverted U-shaped cross-section is provided on the outer wall of the kiln body. A gas combustion pipe and an auxiliary gas combustion pipe are installed within the waste heat chamber. An inverted U-shaped flue gas chamber is provided inside the kiln body. The flue gas chambers between the zones are separated by dividing plates. Each zone has an upper air hole at the top of the kiln body that communicates with the flue gas chamber. Rows of connecting holes communicating with the internal space of the kiln body are arranged on the flue gas chambers on both sides of the kiln body. The drying zone, preheating zone, and cooling zone are located... A partition plate is horizontally installed in the flue gas chamber above the connecting hole. The partition plate divides each flue gas chamber into an upper airflow chamber and a lower air inlet chamber. An exhaust pipe is installed at the bottom of the airflow chamber of the drying zone, preheating zone and cooling zone. An air inlet pipe is installed on the air inlet chamber of the drying zone and cooling zone. The exhaust pipe on the cooling zone is connected to the air inlet pipe on the drying zone through a pipeline. A vent is installed on the partition plate between the preheating zone and the firing zone. The vent connects the flue gas chamber of the firing zone and the air inlet chamber of the preheating zone. The gas combustion pipe and the combustion-supporting pipe are connected to the burner on the firing zone.

[0006] Furthermore, the kiln car is equipped with a refractory brick layer, and the interior of the refractory brick layer has several horizontal holes arranged in rows. The length direction of the horizontal holes is perpendicular to the length direction of the kiln body, and the height of the horizontal holes is the same as the height of the connecting holes. The upper surface of the refractory brick layer is equipped with several air jet holes that communicate with the horizontal holes.

[0007] Furthermore, a row of blow holes are arranged above the connecting hole.

[0008] Furthermore, the exhaust pipe on the preheating zone is connected to the intake pipe on the drying zone via a pipeline.

[0009] Furthermore, a water-cooled jacket is installed on the outer wall of the waste heat chamber.

[0010] Furthermore, a filter screen is provided at the air inlet end of the connecting hole.

[0011] Furthermore, several ash discharge ports are inclined at intervals along the length of the kiln body at the bottom of both sides of the flue gas chamber, and ash storage boxes are set on both sides of the kiln body, with the lower end of the ash discharge port connected to the ash storage box.

[0012] Furthermore, an auger mechanism is installed inside the ash storage box.

[0013] In operation, the ceramic or refractory products to be fired are placed on the kiln car. The kiln car moves the products within the kiln. The burner is turned on, spraying flames and generating high-temperature flue gas to fire the products in the firing zone. The high-temperature flue gas rises continuously and enters the flue gas chamber of the firing zone through the upper air vent. It then splits into two streams flowing to both sides of the kiln. When it reaches the lower part of the flue gas chamber on both sides, it splits again. One part of the flue gas flows back into the firing zone through the connecting hole, mixing with the flue gas in the firing zone to continue firing the products. The other part of the flue gas enters the air inlet chamber of the preheating zone through the vent, and then flows through the connecting hole... The product flows into the preheating zone to preheat it. After floating, it enters the airflow chamber of the preheating zone through the upper air hole and then exits. At the same time, cooling gas is introduced through the air inlet pipe of the cooling zone. The cooling gas enters the air inlet chamber of the cooling zone and flows into the cooling zone through the connecting hole to cool the product in the cooling zone. The cooling gas absorbs heat and mixes with the flue gas. After floating, it enters the airflow chamber of the cooling zone through the upper air hole and then exits. It is then sent to the air inlet chamber of the drying zone through the pipeline. The product enters the drying zone to dry it. After floating, it enters the airflow chamber of the drying zone and finally exits. The product passes through the drying zone, preheating zone, firing zone and cooling zone in sequence to complete the firing process. In this invention, a waste heat chamber is provided on the outer wall of the kiln. During the firing process, some heat is lost into the waste heat chamber. This heat is used to preheat the combustion gas and combustion-supporting gas, increasing their temperature. This preheated gas is then introduced into the burner to improve combustion efficiency, ensuring complete combustion, reducing gas consumption, and minimizing waste heat, thus increasing heat recovery and utilization. Secondly, when the high-temperature flue gas in the firing zone rises, it enters the flue gas chamber, flows downwards within the chamber, and re-enters the firing zone through the connecting holes, mixing with the existing flue gas. This creates a circulating flow of the flue gas within the firing zone, enhancing the agitation and... The mixing effect ensures a relatively uniform and stable temperature across the firing zone, resolving the issue of higher temperatures at the top than at the bottom due to rising high-temperature flue gas. This improves the firing effect and quality of the products, eliminating the need to increase burner power or quantity, thus reducing energy consumption and production costs. Furthermore, this invention utilizes the high flue gas temperature in the firing zone and the low temperature in the cooling zone. Waste heat from the cooling zone is used to dry the products in the drying zone, and waste heat from the firing zone is used to preheat the products in the preheating zone, resulting in a gradual increase in product temperature. This fully utilizes the waste heat generated during firing, effectively recovering and utilizing it. In summary, this invention offers advantages such as minimal heat waste, small temperature difference between the top and bottom of the kiln, excellent firing effect, and energy saving. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0015] Figure 2 for Figure 1 Schematic diagram of the cross-sectional structure of AA;

[0016] Figure 3 for Figure 1 Schematic diagram of the cross-sectional structure of BB;

[0017] Figure 4 for Figure 1 A schematic diagram of the cross-sectional structure of the C-C section;

[0018] Figure 5 for Figure 1 Schematic diagram of the cross-sectional structure of DD;

[0019] In the diagram: 1-Kiln car, 2-Drying zone, 3-Preheating zone, 4-Firing zone, 5-Cooling zone, 6-Residual heat chamber, 7-Gas pipe, 8-Gas-supporting pipe, 9-Flue gas chamber, 10-Separation plate, 11-Upper air hole, 12-Connecting hole, 13-Separation plate, 14-Airflow chamber, 15-Inlet chamber, 16-Exhaust pipe, 17-Inlet pipe, 18-Ventilation hole, 19-Burner, 20-Refractory brick layer, 21-Horizontal hole, 22-Air jet hole, 23-Pulse jet hole, 24-Water cooling jacket, 25-Filter screen, 26-Ash discharge port, 27-Ash storage box, 28-Auger mechanism. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings, but this description is not intended to limit the present invention in any way. Any changes or improvements made based on the present invention shall fall within the protection scope of the present invention.

[0021] like Figures 1-5As shown, this utility model includes a kiln body and a kiln car 1. The kiln body sequentially includes a drying zone 2, a preheating zone 3, a firing zone 4, and a cooling zone 5. Products such as porcelain and refractory materials are dried in the drying zone 2, preheated in the preheating zone 3, fired at high temperature in the firing zone 4, and cooled in the cooling zone 5. A waste heat chamber 6 with an inverted U-shaped cross-section is provided on the outer wall of the kiln body. A gas pipe 7 and an auxiliary gas pipe 8 are installed in the waste heat chamber 6. Some heat from the kiln body dissipates into the waste heat chamber 6, preheating the gas and auxiliary gas, increasing their temperature, and improving combustion efficiency. An inverted U-shaped flue gas chamber 9 is provided inside the kiln body. The flue gas chamber 9 is actually an internal cavity connecting the top and sides of the kiln body. The flue gas chambers 9 between each zone are separated by a zone divider plate 10. Each zone's top of the kiln body has an upper air hole 11 communicating with the flue gas chamber 9. The lower part of the flue gas chambers 9 on both sides of the kiln body is arranged with... The internal space of the kiln is connected by a connecting hole 12. A partition plate 13 is horizontally arranged in the flue gas chamber 9 above the connecting hole 12 at the positions of the drying zone 2, the preheating zone 3, and the cooling zone 5. The partition plate 13 divides each flue gas chamber 9 into an upper airflow chamber 14 and a lower air inlet chamber 15. An exhaust pipe 16 is provided at the bottom of the airflow chamber 14 of the drying zone 2, the preheating zone 3, and the cooling zone 5. An air inlet pipe 17 is provided on the air inlet chamber 15 of the drying zone 2 and the cooling zone 5. The exhaust pipe 16 on the cooling zone 5 is connected to the air inlet pipe 17 on the drying zone 2 through a pipeline. A ventilation hole 18 is provided on the dividing plate 10 between the preheating zone 3 and the firing zone 4. The ventilation hole 18 connects the flue gas chamber 9 of the firing zone 4 and the air inlet chamber 15 of the preheating zone 3. The gas pipe 7 and the combustion-supporting pipe 8 are connected to the burner 19 on the firing zone 4. The burner 19 is an existing device used to spray out the combustion flame of the gas and generate high-temperature flue gas to fire the products in the kiln.

[0022] In operation, the ceramic or refractory products to be fired are placed on the kiln car 1. The kiln car 1 moves the products within the kiln. The burner 19 is turned on, spraying flames and generating high-temperature flue gas to fire the products in the firing zone 4. The high-temperature flue gas rises continuously and enters the flue gas chamber 9 of the firing zone 4 through the upper air hole 11. It then splits into two streams flowing to both sides of the kiln. When it reaches the lower part of both sides of the flue gas chamber 9, it splits again. One part of the flue gas flows back into the firing zone 4 through the connecting hole 12, mixing with the flue gas in the firing zone 4 to continue firing the products. The other part of the flue gas enters the air inlet chamber 15 of the preheating zone 3 through the air vent 18, and then flows into the preheating zone 3 through the connecting hole 12. The products in the preheating zone 3 are preheated, float up and enter the airflow chamber 14 of the preheating zone 3 through the upper air hole 11, and then exit. At the same time, cooling gas is introduced through the air inlet pipe 17 of the cooling zone 5. The cooling gas enters the air inlet chamber 15 of the cooling zone 5, flows into the cooling zone 5 through the connecting hole 12, and cools the products in the cooling zone 5. The cooling gas absorbs the heat of the products and mixes with the flue gas. After floating up, it enters the airflow chamber 14 of the cooling zone 5 through the upper air hole 11, and then exits and is sent to the air inlet chamber 15 of the drying zone 2 through the pipeline. The products enter the drying zone 2 to dry. After floating up, it enters the airflow chamber 14 of the drying zone 2 and finally exits. The products pass through the drying zone 2, the preheating zone 3, the firing zone 4 and the cooling zone 5 in sequence to complete the firing process.

[0023] In this invention, a waste heat chamber 6 is provided on the outer wall of the kiln. During the firing process of the products inside the kiln, some heat is lost into the waste heat chamber 6. This heat is used to preheat the combustion gas and combustion-supporting gas, increasing their temperature. Then, it is introduced into the burner 19 to improve the combustion efficiency of the combustion gas, ensuring complete combustion, reducing gas consumption, and minimizing waste heat, thus improving heat recovery and utilization. Secondly, when the high-temperature flue gas in the firing zone 4 rises, it enters the flue gas chamber 9 and flows downward within it. It then re-enters the firing zone 4 through the connecting hole 12, mixing with the flue gas there. This creates a circulating flow of the flue gas within the firing zone 4, enhancing the agitation of the high-temperature flue gas. The mixing effect ensures that the temperature in each part of the firing zone 4 is relatively uniform and stable, solving the problem of the upper temperature being higher than the lower temperature caused by the rising of high-temperature flue gas. This improves the firing effect of the products and thus improves the firing quality of the products. There is no need to increase the power or number of burners 19, reducing energy consumption and production costs. In addition, in this invention, based on the characteristics of high flue gas temperature in the firing zone 4 and low flue gas temperature in the cooling zone 5, the waste heat of the flue gas in the cooling zone 5 is used to dry the products in the drying zone 2, and the waste heat of the flue gas in the firing zone 4 is used to preheat the products in the preheating zone 3, so that the product temperature gradually increases. This fully utilizes the waste heat generated during the product firing process and effectively recovers and utilizes the waste heat.

[0024] A refractory brick layer 20 is installed on the kiln car 1. Several horizontal holes 21 are arranged in rows inside the refractory brick layer 20. The length direction of the horizontal holes 21 is perpendicular to the length direction of the kiln body, and the height of the horizontal holes 21 is the same as the height of the connecting holes 12. Several air jet holes 22 connected to the horizontal holes 21 are provided on the upper surface of the refractory brick layer 20. During product firing, flue gas or cooling gas is ejected from the connecting holes 12. Since the height of the horizontal holes 21 is the same as the height of the connecting holes 12, when the flue gas or cooling gas is ejected, it will be injected into the horizontal holes 21 and then ejected from the air jet holes 22. The ejected flue gas dries, preheats, and fires the product, while the ejected cooling gas cools the product. The flue gas or cooling gas is ejected simultaneously from various parts of the kiln body, allowing for relatively uniform heating or cooling of the product.

[0025] Above the connecting hole 12, a row of blowing holes 23 are arranged. During operation, flue gas or cooling gas enters the kiln body through the connecting hole 12 and is injected into the horizontal hole 21, then ejected upwards from the jet hole 22. The ejected gas mainly targets the interior of the product, while the gas ejected from the blowing holes 23 can be directly sprayed towards the exterior of the product, improving the firing or cooling efficiency. In this invention, the product is dried, preheated, and fired in the drying zone 2, preheating zone 3, and firing zone 4, and cooled in the cooling zone 5.

[0026] The exhaust pipe 16 on the preheating zone 3 is connected to the air inlet pipe 17 on the drying zone 2 via a pipeline. When this invention is in operation, some of the flue gas in the firing zone 4 will enter the preheating zone 3 through the vent 18. The residual heat of the flue gas in the firing zone 4 will be used to preheat the products in the preheating zone 3, thereby improving the heat utilization rate. After the flue gas preheats the products in the preheating zone 3, the exhaust flue gas still contains a large amount of heat. It will be sent to the drying zone 2 through the pipeline to dry the products in the drying zone 2, thereby further improving the heat utilization rate.

[0027] A water-cooled jacket 24 is provided on the outer wall of the waste heat chamber 6. When this utility model is running, the heat in the kiln will be dissipated into the flue gas chamber 9. Most of the heat will be absorbed by the gas and combustion-supporting gas in the gas pipe 7 and combustion-supporting pipe 8. However, a lot of heat will still accumulate in the waste heat chamber 6 and continuously dissipate from the outer wall of the waste heat chamber 6, resulting in waste. After the water-cooled jacket 24 is provided, cooling water is introduced into the water-cooled jacket 24. The cooling water absorbs the above-mentioned heat and produces hot water. The hot water can be used for system or domestic purposes, and heat waste is avoided and heat loss is reduced.

[0028] A filter screen 25 is provided at the air inlet end of the connecting hole 12. In this utility model, the flue gas flows in the flue gas chamber 9 and enters the kiln body through the connecting hole 12. Considering that the flue gas may carry a certain amount of dust and impurities, these dust particles are entrained by the flue gas and will flow into the kiln body along with the flue gas. The dust particles in the flue gas will rush towards the products that need to be fired, which may affect the surface quality of the products or even cause damage to the products. Therefore, a filter screen 25 is provided to remove these dust and impurities, thereby filtering out the dust and impurities in the flue gas.

[0029] Several ash discharge ports 26 are provided at intervals along the length of the kiln body at the bottom of both sides of the flue gas chamber 9. Ash storage boxes 27 are provided on both sides of the kiln body. The lower end of the ash discharge port 26 is connected to the ash storage box 27. During long-term use, a lot of dust and impurities will accumulate at the bottom of both sides of the flue gas chamber 9. The ash discharge ports 26 are provided in order to discharge this dust. The dust can be discharged from the ash discharge port 26 into the ash storage box 27. It is only necessary to discharge the dust from the ash storage box 27 periodically.

[0030] The ash storage box 27 is equipped with an auger mechanism 28. As the usage time increases, a certain amount of dust will accumulate at the bottom of the flue gas chamber 9. This dust will fall into the ash storage box 27 along the ash discharge port 26. The auger mechanism 28 is existing technology. Activating the auger mechanism 28 can remove the dust in the ash storage box 27 without manual handling, which is highly efficient.

Claims

1. An energy-saving tunnel kiln capable of effectively recovering and utilizing waste heat, comprising a kiln body and a kiln car (1), wherein the kiln body sequentially comprises a drying zone (2), a preheating zone (3), a firing zone (4), and a cooling zone (5), characterized in that: The outer wall of the kiln is provided with a waste heat chamber (6) with an inverted U-shaped cross section. The waste heat chamber (6) is provided with a gas pipe (7) and a gas-supporting pipe (8). The inside of the kiln is provided with a flue gas chamber (9) with an inverted U-shaped cross section. The flue gas chambers (9) between each zone are separated by a zone divider plate (10). The top of the kiln body of each zone is provided with an upper air hole (11) that communicates with the flue gas chamber (9). The lower part of the flue gas chambers (9) on both sides of the kiln body is provided with a row of connecting holes (12) that communicate with the internal space of the kiln body. The flue gas chambers (9) above the connecting holes (12) at the positions of the drying zone (2), the preheating zone (3) and the cooling zone (5) are respectively provided with a horizontal partition plate (13). The partition plate (13) divides the flue gas chambers (9) of each zone into upper airflows. The air intake chamber (14) and the air intake chamber (15) below are provided with exhaust pipes (16) at the bottom of the airflow chamber (14) of the drying zone (2), the preheating zone (3) and the cooling zone (5). The air intake chamber (15) of the drying zone (2) and the cooling zone (5) are provided with air intake pipes (17). The exhaust pipe (16) on the cooling zone (5) is connected to the air intake pipe (17) on the drying zone (2) through a pipeline. The partition plate (10) between the preheating zone (3) and the firing zone (4) is provided with ventilation holes (18). The ventilation holes (18) are connected to the flue gas chamber (9) of the firing zone (4) and the air intake chamber (15) of the preheating zone (3). The gas pipe (7) and the combustion-supporting pipe (8) are connected to the burner (19) on the firing zone (4).

2. The energy-saving tunnel kiln that can effectively recover and utilize waste heat according to claim 1, characterized in that: The kiln car (1) is provided with a refractory brick layer (20). The interior of the refractory brick layer (20) is provided with a number of horizontal holes (21). The length direction of the horizontal holes (21) is perpendicular to the length direction of the kiln body. The height of the horizontal holes (21) is the same as the height of the connecting hole (12). The upper surface of the refractory brick layer (20) is provided with a number of air jet holes (22) that communicate with the horizontal holes (21).

3. The energy-saving tunnel kiln that can effectively recover and utilize waste heat according to claim 2, characterized in that: Above the connecting hole (12), there are rows of blow holes (23).

4. The energy-saving tunnel kiln that can effectively recover and utilize waste heat according to claim 1, characterized in that: The exhaust pipe (16) on the preheating zone (3) is connected to the intake pipe (17) on the drying zone (2) via a pipeline.

5. The energy-saving tunnel kiln that can effectively recover and utilize waste heat according to claim 1, characterized in that: A water-cooled jacket (24) is provided on the outer wall of the waste heat chamber (6).

6. The energy-saving tunnel kiln that can effectively recover and utilize waste heat according to claim 1, characterized in that: A filter (25) is provided at the air inlet end of the connecting hole (12).

7. An energy-saving tunnel kiln that can effectively recover and utilize waste heat according to claim 1, characterized in that: Several ash discharge ports (26) are provided at intervals along the length of the kiln body at the bottom of both sides of the flue gas chamber (9). Ash storage boxes (27) are provided on both sides of the kiln body. The lower end of the ash discharge port (26) is connected to the ash storage box (27).

8. An energy-saving tunnel kiln that can effectively recover and utilize waste heat according to claim 7, characterized in that: The ash storage box (27) is equipped with an auger mechanism (28).

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