Flue gas recycling system of rotary hearth furnace

Abstract

The utility model relates to a flue gas recycling system of a rotary hearth furnace, and belongs to the field of waste gas treatment in ferrous metallurgical industry. Comprising a rotary hearth furnace, a waste heat boiler, a flue gas furnace, a green pellet drying machine and an exhaust funnel which are sequentially connected through pipelines, and flue gas generated by the rotary hearth furnace sequentially passes through the waste heat boiler, the flue gas furnace and the green pellet drying machine and then is exhausted through the exhaust funnel. An outlet pipeline of the waste heat boiler is divided into a first branch pipe, a second branch pipe and a third branch pipe, the first branch pipe is connected to an inlet of the flue gas furnace, the second branch pipe is connected to an inlet of the green ball dryer, and the third branch pipe is connected to an inlet of the exhaust funnel. The first branch pipe is provided with a one-step air mixing adjusting valve, the second branch pipe is provided with a two-step air mixing adjusting valve, and the third branch pipe is provided with an accident emptying valve. The tail flue gas exhausted by the rotary hearth furnace is completely recycled to a green pellet drying process, tail gas heat is utilized to the greatest extent, the heat utilization efficiency is improved, and the overall process energy consumption of the rotary hearth furnace is reduced.

Description

Technical Field

[0001] The utility model belongs to the field of waste gas treatment in the iron and steel metallurgical industry and relates to a rotary hearth furnace flue gas circulation and reuse system. Background Art

[0002] In order to solve the problem of disposing a large amount of iron- and zinc-containing dust and mud in the steel industry, the rotary hearth furnace is widely used due to its wide applicability of raw materials, good product indicators, and high working efficiency. At present, the fuel of the general rotary hearth furnace is rich coal gas, and the flue gas generated is directly discharged into the atmosphere after waste heat recovery, filtration and purification. The exhaust gas temperature is between 140℃ and 200℃, which causes a certain amount of heat waste. Utility Model Content

[0003] In view of this, the purpose of the utility model is to provide a rotary hearth furnace flue gas recycling system to improve the utilization of tail gas heat and reduce the energy consumption of the overall process of the rotary hearth furnace.

[0004] In order to achieve the above-mentioned purpose, the utility model provides a rotary hearth furnace flue gas recycling system, comprising a rotary hearth furnace, a waste heat boiler, a flue gas furnace, a pellet dryer and an exhaust pipe connected in sequence through pipelines, and the flue gas generated by the rotary hearth furnace passes through the waste heat boiler, the flue gas furnace and the pellet dryer in sequence and is discharged from the exhaust pipe. The outlet pipe of the waste heat boiler is divided into a first branch pipe, a second branch pipe and a third branch pipe, the first branch pipe is connected to the inlet of the flue gas furnace, the second branch pipe is connected to the inlet of the pellet dryer, and the third branch pipe is connected to the inlet of the exhaust pipe.

[0005] Optionally, a flue gas dust collector and a main induced draft fan are sequentially arranged between the waste heat boiler and the flue gas furnace along the flue gas flow direction, and the outlet pipe of the waste heat boiler is divided into a first branch pipe, a second branch pipe and a third branch pipe after the main induced draft fan.

[0006] Optionally, a pellet drying dust collector and a dust removal fan are arranged in sequence between the pellet dryer and the exhaust pipe along the flue gas flow direction.

[0007] Optionally, a one-step air mixing regulating valve is provided on the first branch pipe, a two-step air mixing regulating valve is provided on the second branch pipe, and an emergency drain valve is provided on the third branch pipe.

[0008] Optionally, flow detectors are provided on all or part of the first branch pipe, the second branch pipe and the third branch pipe.

[0009] Optionally, an air bypass pipe is provided on the connecting pipe between the waste heat boiler and the flue gas dust collector.

[0010] Optionally, an air mixing valve is provided on the air bypass duct.

[0011] Optionally, the flue gas furnace is provided with an air duct and a gas duct.

[0012] Optionally, an air regulating valve is provided on the air pipeline, and a gas regulating valve is provided on the gas pipeline.

[0013] Optionally, pressure detectors and temperature detectors are provided on all or part of the inlet ducts of the waste heat boiler, the flue gas dust collector, the main induced draft fan, the pellet dryer and the pellet dryer dust collector.

[0014] The beneficial effects of the utility model are:

[0015] The recycling system provided by the utility model recycles all tail gas discharged from the rotary hearth furnace to the green ball drying process, making maximum use of the tail gas heat, improving the heat utilization efficiency, and reducing the overall process energy consumption of the rotary hearth furnace.

[0016] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and will be apparent to those skilled in the art based on the following examination and research, or can be taught from the practice of the present invention to some extent. The objectives and other advantages of the present invention can be achieved and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to make the purpose, technical solution and advantages of the utility model clearer, the utility model will be described in detail below in conjunction with the accompanying drawings, in which:

[0018] Figure 1 The utility model provides a schematic structural diagram of the rotary hearth furnace flue gas recycling system.

[0019] Figure numerals: 1-rotary hearth furnace; 2-waste heat boiler; 3-flue gas dust collector; 4-main induced draft fan; 5-flue gas furnace; 6-raw ball dryer; 7-raw ball dryer dust collector; 8-dust removal fan; 9-exhaust chimney; 10-air mixing valve; 11-one-step air mixing regulating valve; 12-two-step air mixing regulating valve; 13-accidental exhaust valve; 14-gas regulating valve; 15-air regulating valve; 16-pressure detection; 17-temperature detector 18-flow detector; 19-first sub-in-charge; 20-second sub-in-charge; 21-third sub-in-charge. DETAILED DESCRIPTION

[0020] The following describes the implementation of the present invention through specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific implementations, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner. The following embodiments and the features in the embodiments can be combined with each other without conflict.

[0021] Among them, the drawings are only used for illustrative explanations, and they only represent schematic diagrams rather than actual pictures, and should not be understood as limitations on the present utility model. In order to better illustrate the embodiments of the present utility model, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0022] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "front", "back" and the like indicate directions or positional relationships, they are based on the directions or positional relationships shown in the drawings, which are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as a limitation on the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0023] See also Figure 1 The utility model provides a rotary hearth furnace flue gas recycling system, comprising a rotary hearth furnace 1, a waste heat boiler 2, a flue gas dust collector 3, a main induced draft fan 4, a flue gas furnace 5, a pellet dryer 6, a pellet drying dust collector 7, a dust removal fan 8 and an exhaust pipe 9 which are sequentially connected through pipelines, and pressure detectors 16 and temperature detectors 17 are fully or partially provided on the inlet pipelines of the waste heat boiler 2, the flue gas dust collector 3, the main induced draft fan 4, the pellet dryer 6 and the pellet drying dust collector 7. Preferably, pressure detectors 16 and temperature detectors 17 are all provided on the inlet pipelines of the waste heat boiler 2, the flue gas dust collector 3, the main induced draft fan 4, the pellet dryer 6 and the pellet drying dust collector 7 to monitor the pressure and temperature conditions of the flue gas at different points in the system.

[0024] The outlet duct of the main induced draft fan 4 is divided into a first branch pipe 19, a second branch pipe 20 and a third branch pipe 21. The first branch pipe 19 is connected to the inlet of the flue gas furnace 5 to be used as the mixed air of the flue gas furnace 5; the second branch pipe 20 is connected to the inlet of the green ball dryer 6 to be mixed with the outlet flue gas of the flue gas furnace 5; the third branch pipe 21 is connected to the inlet of the exhaust chimney 9 to be used as an emergency discharge channel.

[0025] Further, the first branch pipe 19 is provided with a one-step air mixing regulating valve 11, the second branch pipe 20 is provided with a two-step air mixing regulating valve 12, and the third branch pipe 21 is provided with an emergency drain valve 13. The first branch pipe 19, the second branch pipe 20 and the third branch pipe 21 are all or partially provided with flow detectors 18, preferably, the first branch pipe 19, the second branch pipe 20 and the third branch pipe 21 are all provided with flow detectors 18. The control of the one-step air mixing regulating valve 11 and the two-step air mixing regulating valve 12 forms a PID loop with the signal of the temperature detector 17 at the outlet of the flue gas furnace 5 and the inlet of the green ball dryer 6.

[0026] Furthermore, an air bypass duct is provided on the connecting duct between the waste heat boiler 2 and the flue gas dust collector 3, and an air mixing valve 10 is provided on the air bypass duct. The control of the air mixing valve 10 forms a PID loop with the flue gas temperature signal at the inlet of the flue gas dust collector 3. The fuel of the flue gas furnace 5 is coal gas or natural gas, and an air duct and a gas duct are provided on it. An air regulating valve 15 is provided on the air duct, and the combustion-supporting air volume is controlled by the air regulating valve 15. A gas regulating valve 14 is provided on the gas duct of the flue gas furnace 5. The flue gas generated by the rotary hearth furnace 1 is introduced into the flue gas furnace 5 after being utilized once by the waste heat boiler 2, and is mixed twice with the high-temperature flue gas generated by the combustion in the flue gas furnace 5 for secondary utilization by the green ball dryer 6, and finally discharged from the exhaust pipe 9.

[0027] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model rather than to limit it. Although the utility model has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the technical solution of the utility model can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the utility model.

Claims

1. A rotary hearth furnace flue gas recycling system, characterized in that: The invention comprises a rotary hearth furnace (1), a waste heat boiler (2), a flue gas furnace (5), a pellet dryer (6) and an exhaust pipe (9) which are connected in sequence through pipelines, wherein the flue gas generated by the rotary hearth furnace (1) passes through the waste heat boiler (2), the flue gas furnace (5) and the pellet dryer (6) in sequence and is then discharged from the exhaust pipe (9); wherein: The outlet pipe of the waste heat boiler (2) is divided into a first branch pipe (19), a second branch pipe (20) and a third branch pipe (21), the first branch pipe (19) is connected to the inlet of the flue gas furnace (5), the second branch pipe (20) is connected to the inlet of the green ball dryer (6), and the third branch pipe (21) is connected to the inlet of the exhaust chimney (9).

2. The system according to claim 1, characterized in that: A flue gas dust collector (3) and a main induced draft fan (4) are arranged in sequence between the waste heat boiler (2) and the flue gas furnace (5) along the flue gas flow direction, and the outlet pipe of the waste heat boiler (2) is divided into a first branch pipe (19), a second branch pipe (20) and a third branch pipe (21) after the main induced draft fan (4).

3. The system according to claim 2, characterized in that: A pellet drying dust collector (7) and a dust removal fan (8) are arranged in sequence between the pellet dryer (6) and the exhaust pipe (9) along the flue gas flow direction.

4. The system according to any one of claims 1 to 3, characterized in that: The first branch pipe (19) is provided with a one-step air mixing regulating valve (11), the second branch pipe (20) is provided with a two-step air mixing regulating valve (12), and the third branch pipe (21) is provided with an emergency drain valve (13).

5. The system according to any one of claims 1 to 3, characterized in that: The first branch pipe (19), the second branch pipe (20) and the third branch pipe (21) are all or partially provided with flow detectors (18).

6. The system according to claim 2, characterized in that: An air bypass pipe is provided on the connecting pipe between the waste heat boiler (2) and the flue gas dust collector (3).

7. The system according to claim 6, characterized in that: The air bypass duct is provided with an air mixing valve (10).

8. The system according to any one of claims 1 to 3, characterized in that: The flue gas furnace (5) is provided with an air duct and a gas duct.

9. The system according to claim 8, characterized in that: The air pipeline is provided with an air regulating valve (15), and the gas pipeline is provided with a gas regulating valve (14).

10. The system according to claim 3, characterized in that: The inlet ducts of the waste heat boiler (2), the flue gas dust collector (3), the main induced draft fan (4), the green ball dryer (6) and the green ball dryer dust collector (7) are all or partially provided with a pressure detector (16) and a temperature detector (17).

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