Three-section type flue gas system of green pellet dryer of rotary hearth furnace

Abstract

The utility model belongs to the field of flue gas waste heat utilization, and relates to a three-section flue gas system of a green ball dryer of a rotary hearth furnace, which divides a box body of the green ball dryer into a preheating section, a drying section I and a drying section II along a material conveying direction, and wind-shield walls are arranged among the sections to prevent wind channeling. Rotary hearth furnace tail gas with the temperature of 100-250 DEG C is introduced into the first drying section, flue gas furnace flue gas with the temperature of 200-400 DEG C is introduced into the second drying section, and outlet flue gas of the second drying section is introduced to the preheating section for waste heat utilization and is finally discharged after being converged with outlet flue gas of the first drying section. The system controls the mixing amount of the tail gas of the rotary hearth furnace through the regulating valve, stabilizes the flue gas temperature of each section, and ensures that the drying process is stable. By means of sectional type drying and waste heat recycling, heat utilization efficiency is improved, energy consumption is reduced, the pellet blasting rate and the pulverization rate of pellets are reduced, production efficiency and product quality are improved, and remarkable energy-saving and environment-friendly benefits are achieved.

Description

Technical Field

[0001] This utility model belongs to the field of flue gas waste heat utilization and relates to a three-stage flue gas system for a rotary hearth furnace green pellet dryer. Background Technology

[0002] To address the challenge of disposing of large quantities of iron- and zinc-containing dust and sludge in the steel industry, the rotary hearth furnace process has been widely adopted due to its advantages of wide raw material applicability, good product performance, and high efficiency. The green pellet dryer is a crucial piece of equipment in the rotary hearth furnace production line, requiring the pellets to be dried to a moisture content of <2%. Green pellet dryers typically use flue gas generated by a flue gas furnace for direct contact heat exchange with the pellets during drying. This invention relates to a three-stage flue gas system for a rotary hearth furnace green pellet dryer, dividing the dryer's casing into three sections from the inlet to the outlet: a preheating section, a first drying section, and a second drying section. Windbreaks are installed within the casing between each section to prevent cross-flow. The first and second drying sections introduce rotary hearth furnace tail gas and flue gas from the flue gas furnace, respectively. The flue gas from the second drying section is discharged and then recirculated to the preheating section for reuse, ultimately merging with the outlet flue gas from the first drying section before being discharged. On the one hand, this system can make full use of the waste heat of the rotary hearth furnace, improve heat utilization efficiency, reduce the energy consumption of the flue gas furnace, and reduce the energy consumption of the production line process. On the other hand, since the green pellet drying process is carried out in three stages, the drying temperature rise curve is more gradual, and the pellet temperature increases step by step, reducing the probability of "ball bursting", reducing the pellet pulverization rate, and improving production efficiency. Utility Model Content

[0003] In view of this, the purpose of this utility model is to provide a three-stage flue gas system for a rotary hearth furnace green pellet dryer, which significantly improves drying efficiency and pellet quality through segmented design, waste heat circulation and precise temperature control.

[0004] To achieve the above objectives, this utility model provides the following technical solution: a three-stage flue gas system for a rotary hearth furnace green pellet dryer. The green pellet dryer is divided into a preheating section, a first drying section, and a second drying section along the material conveying direction from the feed end to the discharge end. The first drying section introduces exhaust gas from the rotary hearth furnace, and the second drying section introduces flue gas from the flue gas furnace. The outlet flue gas from the second drying section is sent to the preheating section for waste heat utilization, and the outlet flue gas from the preheating section merges with the outlet flue gas from the first drying section before being discharged. Windbreak walls are provided between the preheating section, the first drying section, and the second drying section to prevent air leakage. This system uses a three-stage stepped temperature control to make the pellet temperature rise curve smooth, reducing pellet bursting and pulverization rates.

[0005] Optionally, the green pellet dryer is a fully enclosed device with windbreak walls installed between adjacent sections to isolate the airflow between sections.

[0006] Optionally, the temperature of the exhaust gas from the rotary hearth furnace introduced into the drying section is 100℃~250℃.

[0007] Optionally, the flue gas temperature introduced into the second drying stage is 200℃~400℃.

[0008] Optionally, the flue gas duct of the second drying stage is connected to the tail gas branch of the rotary hearth furnace, and the tail gas mixing amount is controlled by a regulating valve to stabilize the inlet flue gas temperature of the second drying stage.

[0009] Optionally, the inlet flue gas temperature of the preheating section is 100℃~220℃, and the combined exhaust flue gas temperature of the preheating section and the drying section is 100℃~150℃.

[0010] Optionally, the outlet flue gas duct of the preheating section is connected to the tail gas branch of the rotary hearth furnace, and the tail gas mixing amount is controlled by a regulating valve to stabilize the outlet flue gas temperature of the preheating section.

[0011] Optionally, pressure, temperature, and flow detection instruments and regulating valves are installed on the preheating section, the first drying section, and the second drying section, as well as on the inlet and outlet pipes, for real-time monitoring and adjustment of flue gas parameters.

[0012] Optionally, the flue gas from the second drying stage can be sent to the preheating stage after passing through the material layer, forming a waste heat recycling path.

[0013] The beneficial effects of this utility model are as follows: This utility model provides a three-stage flue gas system for a rotary hearth furnace green pellet dryer. By dividing the green pellet dryer housing into a preheating section, a first-stage drying section, and a second-stage drying section, and introducing rotary hearth furnace tail gas and flue gas from the flue gas furnace respectively, it achieves efficient utilization of flue gas waste heat, reduces energy consumption of the flue gas furnace, and lowers the energy consumption of the production line process. The system adopts a stepped, segmented drying method, resulting in a gentler drying temperature rise curve, avoiding the "pellet bursting" phenomenon caused by sudden temperature increases, reducing pellet pulverization rate, and improving production efficiency and product quality. Simultaneously, the system controls the amount of rotary hearth furnace tail gas incorporated through regulating valves, stabilizing the flue gas temperature in each stage and ensuring the stability of the drying process. The fully enclosed design and the installation of windbreak walls effectively prevent air leakage and cross-flow, further improving drying uniformity and efficiency. Furthermore, the system is equipped with pressure, temperature, and flow detection instruments and regulating valves, achieving intelligent monitoring and regulation, ensuring the reliability and stability of system operation. In summary, this system has significant energy-saving and environmental protection benefits, improving production efficiency and product quality.

[0014] Other advantages, objectives, and features of this invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination and study, or may be learned from practice of this invention. The objectives and other advantages of this invention can be realized and obtained through the following description. Attached Figure Description

[0015] To make the objectives, technical solutions, and advantages of this utility model clearer, the preferred embodiments of this utility model will be described in detail below with reference to the accompanying drawings, wherein:

[0016] Figure 1 This is a schematic diagram of the overall system of this utility model.

[0017] Figure labels: Preheating section 1, Drying section 1 2, Drying section 2 3. Detailed Implementation

[0018] The following specific examples illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification. This utility model can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this utility model. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this utility model. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0019] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the present invention. To better illustrate the embodiments of the present invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0020] In the accompanying drawings of this utility model, the same or similar reference numerals correspond to the same or similar components. In the description of this utility model, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting this utility model. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0021] Please see Figure 1 This is a three-stage flue gas system for a rotary hearth furnace green pellet dryer, including a green pellet dryer housing. The housing is divided into a preheating section 1, a first drying section 2, and a second drying section 3 along the material conveying direction from the feed end to the discharge end. Windbreak walls are installed between each section to prevent cross-flow and ensure the independence of airflow in each section.

[0022] Preheating section 1 is located at the feed end of the green pellet dryer housing and is mainly used for preliminary heating of the incoming green pellets. The inlet flue gas temperature of preheating section 1 is 100℃~220℃, and the flue gas originates from the outlet flue gas of drying section 2 3 and is introduced to preheating section 1 through a pipeline. The outlet flue gas of preheating section 1 and the outlet flue gas of drying section 1 2 are merged through a pipeline before being discharged, and the temperature of the merged flue gas is 100℃~150℃. In order to stabilize the outlet flue gas temperature of preheating section 1, a rotary hearth furnace tail gas branch is connected to the outlet flue gas pipeline of preheating section 1, and the tail gas mixing amount is controlled by a regulating valve.

[0023] Drying section 2 is located after preheating section 1 and is mainly used for preliminary drying of green pellets. Drying section 2 introduces exhaust gas from the rotary hearth furnace, with a temperature of 100℃~250℃, which enters drying section 2 through a pipeline. The exhaust gas from drying section 2 is then discharged after merging with the exhaust gas from preheating section 1 through a pipeline.

[0024] Drying section 3, located after drying section 2, is primarily used for the final drying of green pellets. Flue gas from the flue gas furnace, with a temperature of 200℃~400℃, is introduced into drying section 3 via pipeline. To stabilize the inlet flue gas temperature of drying section 3, a rotary hearth furnace tail gas branch is connected to the flue gas pipeline, and the tail gas mixing rate is controlled by a regulating valve. After passing through the material bed, the flue gas from drying section 3 is piped to preheating section 1 for waste heat utilization.

[0025] Pressure, temperature, and flow detection instruments and regulating valves are installed on the preheating section 1, drying section 1 2, and drying section 2 3, as well as on their inlet and outlet pipes. These instruments are used to monitor and regulate the flow, pressure, and temperature of the flue gas in real time, ensuring the stability and reliability of the system operation.

[0026] The working principle of this invention is as follows: green pellets enter the preheating section 1 from the feed end, where they are initially heated by the flue gas in the preheating section 1; then they enter the first drying section 2, where they are initially dried using the exhaust gas from the rotary hearth furnace; finally, they enter the second drying section 3, where they are finally dried using the flue gas from the flue gas furnace. The flue gas from the second drying section 3, after passing through the material layer, is piped back to the preheating section 1 for waste heat utilization, and finally merges with the exhaust gas from the first drying section 2 before being discharged. The system controls the amount of exhaust gas from the rotary hearth furnace introduced through regulating valves to stabilize the flue gas temperature in each section, ensuring the stability and efficiency of the drying process.

[0027] This invention significantly improves drying efficiency and pellet quality through a three-stage design, waste heat recycling, and precise temperature control, while reducing energy consumption and pellet pulverization rate, resulting in significant energy-saving, environmentally friendly, and production benefits.

[0028] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of this utility model and are not intended to limit it. Although this utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solution of this utility model without departing from the spirit and scope of this technical solution, and all such modifications or substitutions should be covered within the scope of the claims of this utility model.

Claims

1. A three-stage flue gas system for a rotary hearth furnace green pellet dryer, characterized in that: The green pellet dryer is divided into a preheating section, a first drying section, and a second drying section along the material conveying direction from the feed end to the discharge end. The first drying section introduces exhaust gas from the rotary hearth furnace, and the second drying section introduces flue gas from the flue gas furnace. The exhaust gas from the second drying section is sent to the preheating section for waste heat utilization, and the exhaust gas from the preheating section is combined with the exhaust gas from the first drying section before being discharged. Windbreak walls are installed between the preheating section, the first drying section, and the second drying section to prevent air leakage. This system uses a three-stage stepped temperature control to make the temperature rise curve of the pellets smooth, reducing pellet bursting and pulverization rates.

2. The three-stage flue gas system for a rotary hearth furnace green pellet dryer according to claim 1, characterized in that: The green pellet dryer is a fully enclosed device, with windbreak walls installed between adjacent sections to isolate the airflow between sections.

3. The three-stage flue gas system for a rotary hearth furnace green pellet dryer according to claim 1, characterized in that: The temperature of the exhaust gas from the rotary hearth furnace introduced into the drying section is 100℃~250℃.

4. The three-stage flue gas system for a rotary hearth furnace green pellet dryer according to claim 1, characterized in that: The flue gas temperature introduced into the second drying stage is 200℃~400℃.

5. The three-stage flue gas system for a rotary hearth furnace green pellet dryer according to claim 4, characterized in that: The flue gas duct of the second drying stage is connected to the tail gas branch of the rotary hearth furnace, and the tail gas mixing amount is controlled by the regulating valve to stabilize the inlet flue gas temperature of the second drying stage.

6. The three-stage flue gas system for a rotary hearth furnace green pellet dryer according to claim 1, characterized in that: The inlet flue gas temperature of the preheating section is 100℃~220℃, and the combined exhaust flue gas temperature of the preheating section and the drying section is 100℃~150℃.

7. The three-stage flue gas system for a rotary hearth furnace green pellet dryer according to claim 1, characterized in that: The flue gas outlet pipe of the preheating section is connected to the tail gas branch of the rotary hearth furnace, and the tail gas mixing amount is controlled by the regulating valve to stabilize the flue gas temperature at the outlet of the preheating section.

8. The three-stage flue gas system for a rotary hearth furnace green pellet dryer according to claim 1, characterized in that: Pressure, temperature, and flow detection instruments and regulating valves are installed on the preheating section, the first drying section, and the second drying section, as well as on the inlet and outlet pipes, for real-time monitoring and adjustment of flue gas parameters.

9. The three-stage flue gas system for a rotary hearth furnace green pellet dryer according to claim 1, characterized in that: The flue gas from the second drying stage is sent to the preheating stage after passing through the material layer, forming a waste heat recycling path.

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