Ceramsite two-step drying and preheating system and method

Abstract

The invention discloses a ceramsite two-step drying and preheating system and method. The ceramsite two-step drying and preheating system comprises a roller screen, a material ball heating machine drying section, a swing feeding mechanism, a material ball preheating section, a kiln tail, a rotary kiln, a kiln head induced draft fan and a high-temperature fan. A material ball heating machine drying section is arranged at the tail end of the roller screen, a swing feeding mechanism is arranged at the running tail end of the material ball heating machine drying section, and a material ball preheating section is arranged at the tail end of the swing feeding mechanism. The pellet preheating section is communicated with efficient ceramsite cooling equipment through the kiln tail and the rotary kiln, and ceramsite is conveyed to ceramsite conveying equipment through the kiln tail, the rotary kiln and the efficient cooling equipment; and gas in the rotary kiln is used for heating the ceramsite on the pellet preheating section through the kiln tail. High-grade heat-resistant materials can be greatly saved, respective control is carried out completely according to respective heat exchange characteristics of the drying section and the preheating section, and the two sections can both achieve high heat efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of ceramsite production, and in particular relates to a two-step drying and preheating system and method for ceramsite. Background Art

[0002] In the existing expanded clay production process, the drying and preheating of expanded clay after molding are carried out in the same rotary equipment or in the same heater. This processing method makes it impossible for the two similar but different thermal processes of drying and cooling to operate according to their respective parameters with the highest thermal efficiency.

[0003] In addition, the process of drying and preheating in the same heater causes the heater to be too long, so that the low-temperature drying part that does not require high-temperature heat-resistant steel also consumes a large part of the high-temperature heat-resistant steel, increasing equipment investment and subsequent maintenance costs. Summary of the invention

[0004] In order to overcome the defects of the above-mentioned prior art, the purpose of the present invention is to provide a two-step drying and preheating system and method for expanded clay. The system and method independently control the air intake of two stages of fluidized beds, and respectively control the wind temperature, air volume, fluidized bed movement speed, and expanded clay ball layer thickness. The system and method have the characteristics of multiple process control means and flexible adjustment, can achieve a significant saving of high-grade heat-resistant materials, and can be controlled separately according to the heat exchange characteristics of the drying and preheating stages, so that both stages can achieve the purpose of higher thermal efficiency.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A two-step drying and preheating system for ceramsite, comprising a roller screen, a drying section of a ball heater, a swing feeding mechanism, a ball preheating section, a kiln tail, a rotary kiln, a kiln head induced draft fan, and a high-temperature fan;

[0007] A ball heater drying section is arranged at the end of the rotary roller screen, a swing feeding mechanism is arranged at the running end of the ball heater drying section, and a ball preheating section is arranged at the end of the swing feeding mechanism;

[0008] The ball preheating section is connected to the high-efficiency cooling equipment of ceramsite through the kiln tail and the rotary kiln, wherein the ceramsite is transported to the ceramsite transporting equipment through the kiln tail, the rotary kiln and the high-efficiency cooling equipment;

[0009] The gas in the rotary kiln passes through the kiln tail to heat the ceramsite in the ball preheating section.

[0010] The drying section and preheating section of the ball heater constitute a ball heater, the head of the high-efficiency cooling device for ceramsite is connected to the kiln head of the rotary kiln, and the tail is connected to the ceramsite conveying device;

[0011] Cyclone dust removal and flue gas denitrification devices are installed on both sides of the ball heater (one on each side). The residual air from the preheating section (high temperature section) of the ball heater enters the high-efficiency cooling equipment of the ceramsite to remove 95% of the dust in the flue gas and denitrify the flue gas to remove NO X Reduction to N 2 , meeting national industrial flue gas emission requirements.

[0012] A high-temperature centrifugal fan is arranged at the rear end of the cyclone dust removal and flue gas denitration device, and the high-temperature centrifugal fan provides power to the flue gas in the rotary kiln and the ball preheating section.

[0013] The drying section of the ball heater is a low-temperature section of the heater, the preheating section of the ball heater is a high-temperature section of the ball heater, and the high-temperature fan is a high-temperature centrifugal fan.

[0014] The ball heater drying section and ball preheating section include a slowly moving fluidized bed structure, a power device for fluidized bed movement, a bellows, a shell, an ash hopper and an air lock valve;

[0015] The fluidized bed is an annular plate chain with perforated grate plates on top and supporting wheels installed below to support the chain plates. The annular plate chain (including the grate plates) moves slowly under the action of power, and the airflow passes through the gaps between the balls and the gaps between the grate plates to exchange heat with the balls. The space between the bellows and the shell that is not occupied by the balls forms a hot air channel. The shell isolates the ball heater from the outside world to form an independent heat exchange space.

[0016] The dust settled in the flue gas enters the ash hopper and then enters the ash return and broken ball recovery system through the material pipe and air lock valve. The air lock valve operates intermittently according to the amount of ash return, which can not only ensure smooth ash discharge but also avoid large amounts of wind leakage.

[0017] A two-step drying and preheating method for ceramsite comprises the following steps:

[0018] Step 1: The wet ceramsite first enters the roller screen, and the broken balls leak from the gap of the roller screen into the ball recovery system, and the intact wet balls pass through the screen surface of the roller screen 1 and enter the low-temperature section of the heater;

[0019] Step 2: The medium-temperature air of about 400°C is introduced into the ceramsite cooler through the cooler. The medium-temperature air is mixed with the outlet air (after denitration treatment) of the preheating section and the cold air (the cold air ratio is adjusted according to the temperature) and then sent to the drying section of the ball heater by the high-temperature fan;

[0020] Step 3: The mixed air passes through the drying section of the ball heater from top to bottom to exchange heat with the wet balls. The wet balls slowly move from the feeding end to the discharging end of the drying section of the ball heater along with the movement of the fluidized bed. The ceramsite balls, after being dehydrated and slightly heated, enter the swing conveyor.

[0021] Step 4: The material balls enter the preheating section through the swing conveyor. The material balls discharge end of the preheating section exchanges heat with the flue gas generated by the rotary kiln. The material balls enter the rotary kiln through the kiln tail. The high-temperature ceramsite at the outlet of the rotary kiln enters the fluidized bed of the high-efficiency cooling equipment. The wind blown by the cooling fan exchanges heat with the high-temperature ceramsite on the fluidized bed. With the movement of the fluidized bed, the gradually cooled ceramsite is transported from the head of the cooler (close to the rotary kiln) to the tail, and then enters the ceramsite conveying equipment and is sent to the ceramsite storage.

[0022] Furthermore, under the action of the high-temperature fan, the flue gas in the rotary kiln moves from the kiln head to the kiln tail, enters the high-temperature section of the ball heater after leaving the kiln tail, and then enters the cyclone dust removal and flue gas denitrification device. After the flue gas dust removal and denitrification, it enters the high-temperature fan, and after leaving the high-temperature fan, it is mixed with the residual air of the cooler and the cold air of the kiln head induced draft fan and enters the low-temperature section of the ball heater.

[0023] In the step 4, the feed end of the ball preheating section is connected to the discharge end of the ball heater drying section through a swing conveying mechanism; the discharge end of the preheating section is connected to the kiln tail of the rotary kiln, and the flue gas in the rotary kiln enters the ball preheating section through the kiln tail. The temperature of the ball preheating section is about 900°C, and it moves from front to back (facing the equipment, the right hand direction is the front and the left hand direction is the back), passes through the material layer of the ball preheating section to exchange heat with the ceramsite balls, and the temperature of the ceramsite balls rises to about 850°C after absorbing heat, and the temperature of the hot flue gas leaving the preheating section drops to about 460°C, and enters the drying section after denitrification treatment.

[0024] In step 4, the ceramsite balls heated to about 850° C. pass through the tail of the rotary kiln and then enter the rotary kiln for calcination.

[0025] The main material of the drying section of the ball heater is boiler steel, and the main material of the preheating section is high-temperature heat-resistant steel.

[0026] In step 3, during this process, the moisture in the wet balls is continuously heated and gasified and taken out, and the 150°C gas after heat exchange is taken out of the drying section of the ball heater and enters the circulating fan. After the raw materials are dried, they are treated by the exhaust gas treatment system and then discharged.

[0027] Beneficial effects of the present invention:

[0028] The present invention occupies a small space, uses less heat-resistant steel, and has a low cost. The preheating process is no longer affected by the fact that the same material bed and material speed are shared with the drying equipment and the thick material layer state with high heat exchange efficiency cannot be operated. It breaks through the thermal efficiency limit of the existing preheating material balls and greatly improves the heat exchange efficiency. The wind temperature after preheating is reduced, and the temperature resistance requirements of the subsequent induced draft equipment are also reduced accordingly.

[0029] The two-stage fluidized bed in the present invention controls the air intake independently, and controls the wind temperature, air volume, fluidized bed movement speed, and ceramsite ball layer thickness respectively. It has the characteristics of multiple process control means and flexible adjustment, can achieve a significant saving of high-grade heat-resistant materials, and can be controlled separately according to the heat exchange characteristics of the drying and preheating stages respectively, so that both stages can achieve high thermal efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the structural flow of the present invention.

[0031] Figure 2 It is a schematic structural diagram of the drying section and the preheating section of the ball heater of the present invention. DETAILED DESCRIPTION

[0032] The present invention will be further described in detail below in conjunction with the accompanying drawings.

[0033] like Figure 1 As shown, a two-step drying and preheating system for ceramsite comprises a roller screen 1, a ball heater drying section 2, a swing feeding mechanism 3, a ball preheating section 4, a kiln tail 5, a rotary kiln 6, a kiln head induced draft fan 7, and a high-temperature fan 10;

[0034] A ball heater drying section 2 is provided at the end of the rotary roller screen 1, a swing feeding mechanism 3 is provided at the operation end of the ball heater drying section 2, and a ball preheating section 4 is provided at the end of the swing feeding mechanism 3;

[0035] The ball preheating section 4 is connected to the high-efficiency cooling device 8 of ceramsite through the kiln tail 5 and the rotary kiln 6, wherein the ceramsite is transported to the ceramsite transporting device through the kiln tail 5, the rotary kiln 6 and the high-efficiency cooling device 8;

[0036] The gas in the rotary kiln 6 heats the ceramsite in the ball preheating section 4 through the kiln tail 5 .

[0037] The ball heater drying section 2 and the ball preheating section 4 constitute a ball heater, the head of the ceramsite high-efficiency cooling device 8 is connected to the kiln head of the rotary kiln 6, and the tail is connected to the ceramsite conveying equipment;

[0038] Cyclone dust removal and flue gas denitrification devices 9 are installed on both sides of the ball heater (one on each side). The residual wind from the preheating section (high temperature section) of the ball heater at the outlet of the ball preheating section 4 enters the high-efficiency cooling device 8 of the ceramsite to remove 95% of the dust in the flue gas and denitrify the flue gas to remove NO X Reduction to N 2 , meeting national industrial flue gas emission requirements.

[0039] A high-temperature centrifugal fan 10 is arranged at the rear end of the cyclone dust removal and flue gas denitration device 9 , and the high-temperature centrifugal fan 10 provides power to the flue gas in the rotary kiln 6 and the ball preheating section 4 .

[0040] The drying section 2 of the ball heater is a low-temperature section of the heater, the preheating section 4 of the ball heater is a high-temperature section of the ball heater, and the high-temperature fan 10 is a high-temperature centrifugal fan.

[0041] like Figure 2 As shown: the ball heater drying section 2 and the ball preheating section 4 include a slowly moving fluidized bed structure, a power device for fluidized bed movement, a bellows, a shell, an ash hopper and an air lock valve;

[0042] The fluidized bed is an annular plate chain with perforated grate plates on top and supporting wheels installed below to support the chain plates. The annular plate chain (including the grate plates) moves slowly under the action of power, and the airflow passes through the gaps between the balls and the gaps between the grate plates to exchange heat with the balls. The space between the bellows and the shell that is not occupied by the balls forms a hot air channel. The shell isolates the ball heater from the outside world to form an independent heat exchange space.

[0043] The dust settled in the flue gas enters the ash hopper and then enters the ash return and broken ball recovery system through the material pipe and air lock valve. The air lock valve operates intermittently according to the amount of ash return, which can not only ensure smooth ash discharge but also avoid large amounts of wind leakage.

[0044] A two-step drying and preheating method for ceramsite comprises the following steps:

[0045] Step 1: The wet ceramsite first enters the roller screen 1, and the broken balls leak from the gap of the roller screen 1 into the ball recovery system, and the intact wet balls pass through the screen surface of the roller screen 1 and enter the low-temperature section 2 of the heater;

[0046] Step 2: The medium-temperature air of about 400°C is introduced into the ceramsite cooler through the cooler 7, and the medium-temperature air is mixed with the outlet air (after denitration treatment) of the preheating section and the cold air (the cold air ratio is adjusted according to the temperature) and then sent to the drying section 2 of the ball heater by the high-temperature fan;

[0047] Step 3: The mixed air passes through the drying section 2 of the ball heater from top to bottom to exchange heat with the wet balls. The wet balls slowly move from the feeding end to the discharging end of the drying section 2 of the ball heater along with the movement of the fluidized bed. The ceramsite balls, after being dehydrated and slightly heated, enter the swing conveyor 3.

[0048] Step 4: The material balls enter the preheating section 4 through the swing conveyor 3, and the material balls discharge end through the preheating section 4 exchanges heat with the flue gas generated by the rotary kiln 6. The material balls enter the rotary kiln 6 through the kiln tail 5. The high-temperature ceramsite at the outlet end of the rotary kiln 6 enters the fluidized bed of the high-efficiency cooling device 8. The wind blown by the cooling fan exchanges heat with the high-temperature ceramsite on the fluidized bed. With the movement of the fluidized bed, the gradually cooled ceramsite is transported from the head of the cooler (close to the side of the rotary kiln 6) to the tail, and then enters the ceramsite conveying equipment and is transported to the ceramsite storage.

[0049] Furthermore, under the action of the high-temperature fan 10, the flue gas in the rotary kiln 6 moves from the kiln head to the kiln tail, enters the high-temperature section 4 of the ball heater after exiting the kiln tail 5, and then enters the cyclone dust removal and flue gas denitrification device 9. After the flue gas is dusted and denitrified, it enters the high-temperature fan 10, and after exiting the high-temperature fan 10, it is mixed with the cooler residual air and cold air of the kiln head induced draft fan 7 and then enters the low-temperature section 2 of the ball heater.

[0050] In the step 4, the feed end of the ball preheating section 4 is connected to the discharge end of the ball heater drying section 2 through the swing conveying mechanism 3; the discharge end of the preheating section 4 is connected to the kiln tail 5 of the rotary kiln 6, and the flue gas in the rotary kiln 6 enters the ball preheating section 4 through the kiln tail 5. The temperature of the ball preheating section 4 is about 900°C, and it moves from front to back (facing the equipment, the right hand direction is the front and the left hand direction is the back), passes through the material layer of the ball preheating section 4 to exchange heat with the ceramsite balls. After absorbing heat, the temperature of the ceramsite balls rises to about 850°C, and the temperature of the hot flue gas exiting the preheating section 4 drops to about 460°C, and enters the drying section 2 after denitration treatment.

[0051] In step 4, the ceramsite balls heated to about 850° C. pass through the rotary kiln tail 6 and then enter the rotary kiln 5 for calcination.

[0052] The main material of the drying section 2 of the ball heater is boiler steel, and the main material of the preheating section is high-temperature heat-resistant steel.

[0053] In step 3, during this process, the moisture in the wet ball is continuously heated and gasified and taken out, and the 150°C gas after heat exchange is taken out of the ball heater drying section 2 and enters the circulating fan. After the raw material is dried, it is treated by the exhaust gas treatment system and then discharged.

[0054] Two-step heating process description:

[0055] This system consists of a roller screen 1, a ball heater drying section 2, a swing feeding mechanism 3, a ball preheating section 4, a gas-solid separator, a kiln head blower, a rotary kiln, and a high-temperature blower;

[0056] The roller screen 1 is used to screen out unqualified balls; the ball heating machine drying section 2 uses low-temperature gas below 400°C to dry the balls, dry out the moisture in the balls, and slightly increase the temperature of the balls; the ball preheating section 4 uses a rotary kiln with a high temperature of 950-1050°C.

[0057] The gas quickly preheats and dries the balls, and the temperature of the balls rises rapidly. The wet balls are conveyed to the roller screen 1 by the belt conveyor, and the unqualified balls are screened out. The qualified balls enter the drying section 2 of the ball heater to be dried, and then enter the ball preheating section 4 by the swing feeding mechanism 3 to be quickly preheated. The preheated ceramsite balls enter the rotary kiln 6 for calcination.

[0058] The two sections of the two-step ball heating equipment are similar in width and height, and the low-temperature section is slightly longer than the high-temperature section. Compared with the drying and preheating of the all-in-one machine, more than 50% of the heat-resistant steel with a heat-resistant grade of 1100°C can be replaced with heat-resistant steel of 500°C, and the cost of refractory materials for the side walls and top cover is reduced by about 17%.

[0059] The high temperature section and low temperature section of the two-step ball heating equipment control the material bed speed and material layer thickness respectively, thereby increasing the material layer thickness in the high temperature section and extending the heat exchange time, thereby increasing the thermal efficiency by more than 5%.

Claims

1. A two-step drying and preheating system for ceramsite, characterized in that: It comprises a roller screen (1), a ball heater drying section (2), a swing feeding mechanism (3), a ball preheating section (4), a kiln tail (5), a rotary kiln (6), a kiln head induced draft fan (7), and a high-temperature fan (10); A ball heater drying section (2) is provided at the end of the rotary roller screen (1), a swing feeding mechanism (3) is provided at the end of the running end of the ball heater drying section (2), and a ball preheating section (4) is provided at the end of the swing feeding mechanism (3); The pellet preheating section (4) is connected to the high-efficiency cooling device (8) for ceramsite via the kiln tail (5) and the rotary kiln (6), wherein the ceramsite is transported to the ceramsite transporting device via the kiln tail (5), the rotary kiln (6) and the high-efficiency cooling device (8); The gas in the rotary kiln (6) heats the ceramsite on the ball preheating section (4) through the kiln tail (5).

2. A two-step drying and preheating system for ceramsite according to claim 1, characterized in that: The ball heater drying section (2) and the ball preheating section (4) constitute a ball heater, the head of the ceramsite high-efficiency cooling device (8) is connected to the kiln head of the rotary kiln (6), and the tail is connected to the ceramsite conveying device; Cyclone dust removal and flue gas denitrification devices (9) are installed on both sides of the pellet heater (one on each side). The residual air of the pellet heater preheating section (high temperature section) of the pellet preheating section (4) enters the high-efficiency cooling device (8) of the ceramsite to remove 95% of the dust in the flue gas and denitrify the flue gas to remove NO X Reduced to N2, meeting national industrial flue gas emission requirements.

3. A two-step drying and preheating system for ceramsite according to claim 2, characterized in that: A high-temperature fan (10) is arranged at the rear end of the cyclone dust removal and flue gas denitration device (9), and the high-temperature fan (10) provides power to the flue gas in the rotary kiln (6) and the ball preheating section (4).

4. A two-step drying and preheating system for ceramsite according to claim 1, characterized in that: The drying section (2) of the ball heater is a low-temperature section of the heater, the preheating section (4) of the ball heater is a high-temperature section of the ball heater, and the high-temperature fan (10) is a high-temperature centrifugal fan.

5. A two-step drying and preheating system for ceramsite according to claim 1, characterized in that: The ball heater drying section (2) and the ball preheating section (4) include a slowly moving fluidized bed structure, a power device for fluidized bed movement, a bellows, a housing, an ash hopper and an air lock valve; The fluidized bed is a circular plate chain with perforated grate plates on top and supporting wheels installed below to support the chain plates. The circular plate chain moves slowly under the action of power, and the airflow passes through the gaps between the balls and the grate plates to exchange heat with the balls. The space between the bellows and the shell that is not occupied by the balls forms a hot air channel. The shell isolates the ball heater from the outside world, forming an independent heat exchange space. The dust settled in the flue gas enters the ash hopper and then passes through the material pipe and air lock valve into the ash return and broken ball recovery system.

6. A preheating method for a ceramsite two-step drying and preheating system according to any one of claims 1 to 5, characterized in that: The steps include: Step 1: The wet ceramsite first enters the roller screen (1), the broken balls leak through the gap of the roller screen (1) and enter the ball recovery system, and the intact wet balls pass through the screen surface of the roller screen (1) and enter the low-temperature section (2) of the heater; Step 2: medium-temperature air of about 400° C. is introduced into the ceramsite cooler through the cooler (7), and the medium-temperature air is mixed with the outlet air (after denitration treatment) of the preheating section and the cold air and then sent to the drying section (2) of the pellet heater by the high-temperature blower; Step 3: The mixed air passes through the drying section (2) of the ball heater from top to bottom to exchange heat with the wet pellets. The wet pellets slowly move from the feed end to the discharge end of the drying section (2) of the ball heater along with the movement of the fluidized bed. The ceramsite pellets, after being dehydrated and slightly heated, enter the swing conveyor (3); Step 4: The pellets pass through the swing conveyor (3) and enter the preheating section (4). The pellets passing through the preheating section (4) are heat-exchanged with the smoke generated by the rotary kiln (6). The pellets pass through the kiln tail (5) and enter the rotary kiln (6). The high-temperature ceramsite at the outlet of the rotary kiln (6) enters the fluidized bed of the high-efficiency cooling device (8). The wind blown in by the cooling fan exchanges heat with the high-temperature ceramsite on the fluidized bed. As the fluidized bed moves, the gradually cooled ceramsite is transported from the head of the cooler to the tail, and then enters the ceramsite transporting device and is transported to the ceramsite storage.

7. The preheating method of a ceramsite two-step drying and preheating system according to claim 6, characterized in that: Under the action of the high-temperature fan (10), the flue gas in the rotary kiln (6) moves from the kiln head to the kiln tail, and after exiting the kiln tail (5), enters the high-temperature section (4) of the ball heater, and then enters the cyclone dust removal and flue gas denitrification device (9). After the flue gas is dusted and denitrified, it enters the high-temperature fan (10), and after exiting the high-temperature fan (10), it is mixed with the residual air of the cooler and the cold air of the kiln head induced draft fan (7) and enters the low-temperature section (2) of the ball heater.

8. The preheating method of a two-step drying and preheating system for ceramsite according to claim 6, characterized in that: In the step 4, the feed end of the ball preheating section (4) is connected to the discharge end of the ball heater drying section (2) through the swing conveying mechanism (3); the discharge end of the preheating section (4) is connected to the kiln tail (5) of the rotary kiln (6), and the flue gas in the rotary kiln (6) enters the ball preheating section (4) through the kiln tail (5). The temperature of the ball preheating section (4) is about 900° C., and the ball passes through the material layer of the ball preheating section (4) to exchange heat with the ceramsite balls. After absorbing heat, the temperature of the ceramsite balls rises to about 850° C., and the temperature of the hot flue gas exiting the preheating section (4) is reduced to about 460° C., and then enters the drying section (2) after denitration treatment.

9. The preheating method of a ceramsite two-step drying and preheating system according to claim 6, characterized in that: In the step (4), the ceramsite balls heated to about 850° C. pass through the rotary kiln tail (6) and then enter the rotary kiln (5) for calcination.

10. The preheating method of a two-step drying and preheating system for ceramsite according to claim 6, characterized in that: In step 3, during this process, the moisture in the wet pellets is continuously heated and vaporized and taken out, and along with the 150°C gas after heat exchange, it is taken out of the pellet heater drying section (2) and enters the circulating fan, and after the raw materials are dried, they are treated by the exhaust gas treatment system and then discharged.

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