Preheating and replacing method for pyrolysis process of rotary kiln and upgrading system

Abstract

The invention discloses a rotary kiln pyrolysis process preheating and replacing method which comprises the following steps: replacing and preheating an upgrading system when a rotary kiln is started, performing low-load operation on the rotary kiln, heating the rotary kiln by a rotary kiln hot blast stove and a flue gas fan, closing a pipeline valve from a dry gas fan to a first dust remover, and performing low-load operation on the rotary kiln; a rotary kiln nitrogen replacement valve is slightly opened, nitrogen enters the rotary kiln through a dry gas guide screw for replacement and heat removal, an oil and gas pipeline is preheated, direct cooling tower spraying cooling water and indirect cooling tower circulating cooling water are put into use, a coal gas fan is started for system circulation, and an electrical tar precipitator outlet is opened to a rotary kiln starting line valve; the invention further discloses a rotary kiln quality improvement system, the rotary kiln pyrolysis process preheating and replacement method is adopted, the start-up time is effectively shortened, the investment and operation cost is saved, and meanwhile a foundation is laid for long-period stable operation of the system.

Description

Technical Field

[0001] This invention relates to the field of coal conversion technology, and in particular to a preheating and replacement method and upgrading system for rotary kiln pyrolysis process. Background Technology

[0002] At present, the domestic coal pyrolysis industry, especially the rotary kiln pyrolysis process of pulverized coal, is not very mature. It often experiences shutdown problems, and the start-up process is long and the operation is cumbersome. Therefore, how to effectively shorten the start-up time and optimize the start-up operation steps, and provide a simple preheating and replacement operation method, has become an important technical problem that needs to be solved by those skilled in the art. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a preheating and replacement method and upgrading system for rotary kiln pyrolysis process that can shorten start-up time and optimize start-up operation steps.

[0004] To achieve the above objectives, the present invention provides the following technical solution: This invention discloses a preheating and displacement method for a rotary kiln pyrolysis process, comprising the following steps: When the rotary kiln is started, the upgrading system is replaced and preheated. The rotary kiln operates at low load. The rotary kiln hot blast stove and flue gas fan heat the rotary kiln. The valve of the dryer gas fan to the first dust collector pipeline is closed. The rotary kiln replacement nitrogen valve is slightly opened. Nitrogen enters the rotary kiln through the dryer gas guide spiral for replacement and heat extraction. The oil and gas pipeline is preheated. At the same time, the direct cooling tower spray cooling water and the indirect cooling tower circulating cooling water are put into operation. The gas fan is started to circulate the system. The valve from the electrostatic precipitator outlet to the rotary kiln start-up line is opened. The valve from the electrostatic precipitator to the flare is closed to establish a circulation system.

[0005] Furthermore, as the temperature rises, the rotary kiln nitrogen replacement valve is opened to increase the nitrogen input and the load on the gas blower. When the temperature of the upgrading system rises to 200-400℃, the nitrogen replacement in the vertical furnace, filter tube dust collector, and electrostatic precipitator is slightly opened to replace the equipment. When the system's circulating gas volume reaches its maximum, the valve to the flare system is opened to discharge the excess circulating gas to the flare, and the system maintains normal operating pressure.

[0006] Furthermore, when the system temperature rises to the feeding temperature, the hot air furnace is adjusted to maintain a constant system temperature. After the system is properly purged, the amount of nitrogen purged from the rotary kiln is reduced, and the valve from the outlet of the electrostatic precipitator to the flare is closed to maintain the normal operating pressure of the system.

[0007] An invention provides a rotary kiln upgrading system, which employs the preheating and replacement method of a rotary kiln pyrolysis process described above. The rotary kiln upgrading system comprises: a rotary kiln, a vertical furnace, a two-stage cyclone dust collector, a filter tube dust collector, a direct cooling tower, an indirect cooling tower, and a gas blower connected in sequence. A hot air furnace is also connected to the tail end of the rotary kiln; The first dust collector and the second dust collector are connected to the first end of the rotary kiln by pipelines. Nitrogen gas, used for purging the rotary kiln, enters the rotary kiln through the pipeline of the first dust collector.

[0008] Furthermore, it also includes an electrostatic precipitator for tar removal, wherein the inlet of the electrostatic precipitator is connected to a nitrogen replacement pipeline, and one outlet of the electrostatic precipitator is connected to the flare, and another outlet is connected to the pipeline from the first dust collector to the rotary kiln.

[0009] Furthermore, the outlet of the first dust collector is sequentially connected to a drying air fan and an venting pipeline.

[0010] Furthermore, the outlet of the second dust collector is sequentially connected to the flue gas fan and the hot air furnace.

[0011] Furthermore, the pipeline between the flue gas fan and the hot air furnace is connected to the desulfurization and denitrification device via a branch line.

[0012] Furthermore, the rotary kiln is connected to a screw feeder at its head end, and the screw feeder is connected to the inlet pipeline of the first dust collector.

[0013] Furthermore, the flue gas collection hood at the beginning of the rotary kiln is connected to the inlet pipeline of the second dust collector.

[0014] In the above technical solution, the present invention provides a preheating and replacement method for rotary kiln pyrolysis process. This method involves introducing replacement nitrogen into the pyrolysis rotary kiln during the start-up and heating process. After heat exchange in the kiln, the temperature of the nitrogen increases, which can both preheat and replace the pipelines and equipment in the subsequent system. This eliminates the complex operation process of separate replacement and preheating in the original traditional process, thus effectively shortening the start-up time and optimizing the operation process.

[0015] In the above technical solution, the rotary kiln upgrading system provided by the present invention adopts the preheating and replacement method of the above-mentioned rotary kiln pyrolysis process, which effectively shortens the start-up time, avoids the need for separate system preheating of equipment and pipelines during start-up, and saves investment and operating costs.

[0016] Secondly, this method can replace the entire system, avoiding the problem of incomplete segmented replacement.

[0017] In addition, this method can form various circulation systems in the entire pyrolysis process system, reduce the overall pressure and temperature fluctuations after feeding during start-up, and lay the foundation for the long-term stable operation of the system. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0019] Figure 1 This is a process flow diagram of a preheating and replacement method for rotary kiln pyrolysis disclosed in this invention.

[0020] Explanation of reference numerals in the attached figures: 1. Rotary kiln; 2. Hot blast stove; 3. Vertical furnace; 4. Two-stage cyclone dust collector; 5. Filter tube dust collector; 6. Direct cooling tower; 7. Indirect cooling tower; 8. Gas fan; 9. Electrostatic precipitator; 10. Nitrogen replacement; 11. Flare removal; 12. First dust collector; 13. Drying gas fan; 14. Second dust collector; 15. Flue gas fan; 16. Desulfurization and denitrification device; 17. Rotary kiln nitrogen replacement. Detailed Implementation

[0021] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0022] See Figure 1 As shown; An invention provides a preheating and displacement method for a rotary kiln pyrolysis process, comprising: When the rotary kiln 1 is started, it replaces and preheats the upgrading system. First, the rotary kiln 1 is started to operate at low load. At the same time, the rotary kiln hot blast stove 2 and flue gas fan 15 are started to heat the rotary kiln 1. The valve of the pipeline from the drying gas fan 13 to the first dust collector 12 is closed. The rotary kiln replacement nitrogen valve 17 is slightly opened. The nitrogen enters the rotary kiln 1 through the drying gas guide spiral to replace and heat it, preheat the oil and gas pipeline, and also play a replacement role. At the same time, the direct cooling tower 6 sprays cooling water and the indirect cooling tower 7 circulates cooling water. The gas fan 8 is started to circulate the system (initially at low load). The valve from the outlet of the electrostatic precipitator 9 to the start-up line of the rotary kiln 1 is opened. The valve from the electrostatic precipitator 9 to the flare 11 is closed to establish a circulation system.

[0023] As the temperature rises, slowly open the rotary kiln replacement nitrogen valve 17 to increase the nitrogen input and the load on the gas blower 8, thereby increasing the system's replacement and preheating gas volume. When the temperature of the upgrading system rises to 200-400℃, slightly open the replacement nitrogen valves of the vertical furnace 3, filter tube dust collector 5, and electrostatic precipitator 9 to replace the equipment. When the system's circulating gas volume reaches its maximum, open the flare 11 system valve to discharge the excess circulating gas to the flare, and maintain the system's normal operating pressure.

[0024] When the system temperature rises to the feeding temperature, adjust the load of the hot air furnace 2 appropriately to maintain a constant system temperature. After the system is properly purged (oxygen content less than 1%), reduce the amount of nitrogen purged by the rotary kiln 1, and at the same time close the valve from the outlet of the electrostatic precipitator 9 to the flare 11. The system should maintain normal operating pressure.

[0025] The preheating and replacement method of this rotary kiln pyrolysis process involves introducing replacement nitrogen into the pyrolysis rotary kiln during the start-up and heating process. After heat exchange within the kiln, the nitrogen's temperature rises, allowing the subsequent system to both preheat and replace pipelines and equipment. This eliminates the complex operation process of separate replacement and preheating as in the traditional process, effectively shortening start-up time and optimizing the operation process.

[0026] See Figure 1 As shown: A rotary kiln upgrading system is invented, which adopts the preheating and replacement method of the above-mentioned rotary kiln pyrolysis process. The rotary kiln upgrading system includes: a rotary kiln 1, a hot blast stove 2, a vertical furnace 3, a two-stage cyclone dust collector 4, a filter tube dust collector 5, a direct cooling tower 6, an indirect cooling tower 7, and a gas blower 8. The rotary kiln 1 is connected in sequence to the vertical furnace 3, the two-stage cyclone dust collector 4, the filter tube dust collector 5, the direct cooling tower 6, the indirect cooling tower 7, and the gas blower 8; The rotary kiln 1 is connected to the hot air furnace 2 at its tail end. The first dust collector 14 and the second dust collector 14 are connected to the first dust collector 14 at its head end through pipelines. The rotary kiln replacement nitrogen gas 17 enters the rotary kiln 1 through the pipeline of the first dust collector 14.

[0027] The quality improvement system also includes an electrostatic precipitator 9, the inlet of which is connected to a replacement nitrogen pipeline 10, and the outlet of the electrostatic precipitator 9 is connected to a flare 11 via one pipeline and to a pipeline from the first dust collector 14 to the rotary kiln 1 via another pipeline. The outlet of the first dust collector 12 is connected in sequence to a drying gas fan 13 and a venting pipeline.

[0028] Preferably, the outlet of the second dust collector 12 is connected in sequence to the flue gas fan 15 and the hot air furnace 2, wherein the pipeline between the flue gas fan 15 and the hot air furnace 2 is connected to the desulfurization and denitrification device 16 through a branch.

[0029] Preferably, the rotary kiln 1 is connected to a screw feeder at its head end, the screw feeder is connected to the inlet pipeline of the first dust collector 12, and the flue gas collection hood at the head end of the rotary kiln 1 is connected to the inlet pipeline of the second dust collector 14.

[0030] In the above technical solution, the present invention provides a preheating and replacement method and system for rotary kiln pyrolysis process. First, the entire pulverized coal pyrolysis process system is preheated and replaced during start-up, which achieves a short start-up time, basically controlled within 24 hours, effectively shortening the start-up time (by half compared to the traditional method). This avoids the need for separate system preheating of equipment and pipelines during start-up, saving investment and operating costs.

[0031] Secondly, this method can replace the entire system, avoiding the problem of incomplete segmented replacement.

[0032] In addition, this method can form various circulation systems in the entire pyrolysis process system, reduce the overall pressure and temperature fluctuations after feeding during start-up, and lay the foundation for the long-term stable operation of the system.

[0033] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A preheating and displacement method for rotary kiln pyrolysis process, characterized in that, Includes the following steps: When the rotary kiln is started, the upgrading system is replaced and preheated. The rotary kiln operates at low load. The rotary kiln hot blast stove and flue gas fan heat the rotary kiln. The valve of the dryer gas fan to the first dust collector pipeline is closed. The rotary kiln replacement nitrogen valve is slightly opened. Nitrogen enters the rotary kiln through the dryer gas guide spiral for replacement and heat extraction. The oil and gas pipeline is preheated. At the same time, the direct cooling tower spray cooling water and the indirect cooling tower circulating cooling water are put into operation. The gas fan is started to circulate the system. The valve from the electrostatic precipitator outlet to the rotary kiln start-up line is opened. The valve from the electrostatic precipitator to the flare is closed to establish a circulation system.

2. The preheating and displacement method for rotary kiln pyrolysis process according to claim 1, characterized in that: When the temperature rises, open the rotary kiln's nitrogen replacement valve to increase the nitrogen input and the load on the gas blower. When the temperature of the upgrading system rises to 200-400℃, slightly open the replacement nitrogen in the vertical furnace, filter tube dust collector, and electrostatic precipitator to replace the equipment. When the system's circulating gas volume reaches its maximum, open the valve to the flare system to discharge the excess circulating gas to the flare, and maintain the system's normal operating pressure.

3. The preheating and replacement method for rotary kiln pyrolysis process according to claim 2, characterized in that: When the system temperature rises to the feeding temperature, adjust the hot air furnace to maintain a constant system temperature. After the system is properly purged, reduce the amount of nitrogen purging gas in the rotary kiln and simultaneously close the valve from the outlet of the electrostatic precipitator to the flare. The system should maintain normal operating pressure.

4. A rotary kiln upgrading system, which employs the preheating and replacement method of the rotary kiln pyrolysis process as described in any one of claims 1-3, characterized in that: The rotary kiln upgrading system includes: a rotary kiln (1), a vertical furnace (3), a secondary cyclone dust collector (4), a filter tube dust collector (5), a direct cooling tower (6), an indirect cooling tower (7), and a gas blower (8) connected in sequence. The rotary kiln (1) is also connected to a hot air furnace (2) at its tail end; The first dust collector (14) and the second dust collector (14) are respectively connected to the first dust collector (14) and the second dust collector (14) through pipelines at the head end of the rotary kiln (1). Nitrogen gas (17) is purged from the rotary kiln and enters the rotary kiln (1) through the pipeline of the first dust collector (14).

5. A rotary kiln upgrading system according to claim 4, characterized in that: It also includes an electrostatic precipitator (9), the inlet of which is connected to a nitrogen (10) pipeline, and one outlet of the electrostatic precipitator (9) is connected to a flare (11), and another outlet is connected to the pipeline from the first dust collector (14) to the rotary kiln (1).

6. A rotary kiln upgrading system according to claim 4, characterized in that: The outlet of the first dust collector (12) is connected in sequence to the dry air blower (13) and the venting pipeline.

7. A rotary kiln upgrading system according to claim 4, characterized in that: The outlet of the second dust collector (12) is connected in sequence to the flue gas fan (15) and the hot air furnace (2).

8. A rotary kiln upgrading system according to claim 7, characterized in that: The pipeline between the flue gas fan (15) and the hot air furnace (2) is connected to the desulfurization and denitrification device (16) via a branch.

9. A rotary kiln upgrading system according to claim 4, characterized in that: The rotary kiln (1) is connected to a screw feeder at its head end, and the screw feeder is connected to the inlet pipeline of the first dust collector (12).

10. A rotary kiln upgrading system according to claim 9, characterized in that: The flue gas collection hood at the beginning of the rotary kiln (1) is connected to the inlet pipeline of the second dust collector (14).

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