Blast furnace natural gas injection heating system

Abstract

The utility model relates to a natural gas injection heating system for a blast furnace and belongs to the field of metallurgical industry. The system comprises a hot-blast stove for generating high-temperature flue gas, a heat exchanger and a blast furnace, a first natural gas inlet, a natural gas outlet, a flue gas inlet and a flue gas outlet which are respectively connected with a natural gas pipeline and a flue gas pipeline are formed in the heat exchanger, the hot blast stove is connected to the flue gas inlet through a high-temperature flue gas pipeline and a first flue gas pipeline, and the blast furnace is connected to the natural gas outlet through the first natural gas pipeline; a second flue gas pipeline communicated to the chimney is arranged on the hot blast stove; and a waste heat recovery device is arranged on the second flue gas pipeline. A central control system electrically connected with the thermometers, the flow adjusting valves and the flow meters is further arranged. The high-temperature flue gas generated by the hot-blast stove is used for preheating the natural gas injected into the blast furnace, so that the requirement of heating the natural gas injected into the blast furnace is met, one-time heat exchange is reduced, the heat efficiency is high, and the fuel ratio of the blast furnace can be reduced.

Description

Technical Field

[0001] This utility model belongs to the field of metallurgical industry and relates to a blast furnace natural gas injection heating system. Background Technology

[0002] With increasing global awareness of environmental protection and the promotion of a low-carbon economy, the requirements for low-carbonization in blast furnace ironmaking processes are becoming increasingly prominent. How to achieve green transformation in this traditional heavy industry has become a focus of attention both inside and outside the industry.

[0003] Some blast furnaces use natural gas injection to reduce the consumption of coke and pulverized coal. However, the low temperature of the natural gas directly entering the blast furnace cannot bring enough heat to the furnace. Therefore, the natural gas needs to be heated. However, how to heat the natural gas in a way that consumes less energy is a topic worthy of research.

[0004] In traditional hot blast stoves, the high-temperature flue gas after combustion is typically maintained at a temperature above 350°C. This gas is used to heat the cold air and gas entering the hot blast stove. The heated cold air and gas then enter the hot blast stove and, after combustion, heat the hot blast stove itself. The heated hot blast stove then heats a large amount of cold air, which is finally sent into the blast furnace. In this process, the heat from the high-temperature flue gas in the hot blast stove undergoes three energy transfers before entering the blast furnace: first, the air and gas are preheated; then, the preheated air and gas are burned in the hot blast stove to heat the stove; and finally, the hot blast stove heats the cold air. As a result, the heat utilization rate is relatively low.

[0005] However, with increasing global environmental awareness and the continuous development of the low-carbon economy, the requirements for low-carbonization in blast furnace ironmaking processes are becoming increasingly stringent. Against this backdrop, there is a lack of mature and effective technological solutions for effectively reducing carbon emissions during blast furnace ironmaking and for more efficiently utilizing the residual heat from the high-temperature flue gas generated by hot blast stove combustion. Therefore, there is an urgent need for a new technology that can simultaneously meet the requirements for low-carbonization of blast furnaces and efficiently utilize the residual heat of hot blast stoves to promote the green transformation and sustainable development of the metallurgical industry. Utility Model Content

[0006] In view of this, the purpose of this utility model is to provide a blast furnace natural gas injection heating system that meets the requirements of blast furnace decarbonization and natural gas injection. It uses high-temperature flue gas from the hot blast stove to heat low-temperature natural gas, and then transports the heated natural gas into the blast furnace, thereby improving the energy utilization efficiency of high-temperature flue gas and reducing the fuel consumption of the blast furnace.

[0007] To achieve the above objectives, this utility model provides the following technical solution:

[0008] A blast furnace pulverized natural gas heating system includes a hot blast stove that generates high-temperature flue gas, and a blast furnace connected to the hot blast stove via a heat exchanger. The heat exchanger is provided with a first natural gas inlet, a natural gas outlet, a flue gas inlet, and a flue gas outlet. The hot blast stove is connected to the flue gas inlet via a first flue gas pipe, and the blast furnace is connected to the natural gas outlet via a first natural gas pipe. High-temperature flue gas enters the heat exchanger through the flue gas inlet, and natural gas before heating enters through the first natural gas inlet for heat exchange. The heated natural gas is then transported to the blast furnace via the first natural gas pipe.

[0009] Optionally, the hot air furnace is provided with a high-temperature flue gas duct, the end of which is away from the hot air furnace is connected to a second flue gas duct and the first flue gas duct respectively; the end of the second flue gas duct away from the high-temperature flue gas duct is connected to a chimney.

[0010] Optionally, a thermometer is installed on the high-temperature flue gas pipeline; a flow regulating valve and a flow meter are sequentially installed on the first flue gas pipeline; a thermometer and a flow regulating valve are sequentially installed on the first natural gas pipeline.

[0011] Optionally, a waste heat recovery device is installed on the second flue gas duct.

[0012] Optionally, a flow regulating valve 12 is provided on the second flue gas duct located between the waste heat recovery device and the hot air furnace.

[0013] Optionally, the first natural gas inlet is connected to a cryogenic natural gas pipeline network via a second natural gas pipeline.

[0014] Optionally, a flow regulating valve, a flow meter, and a thermometer are sequentially installed on the second natural gas pipeline.

[0015] Optionally, the flue gas outlet is connected to the chimney via a third flue gas duct.

[0016] Optionally, a thermometer and a flow regulating valve are sequentially installed on the third flue gas duct.

[0017] Optionally, a central control system is also provided that is electrically connected to each thermometer, flow regulating valve, and flow meter.

[0018] The beneficial effects of this utility model are as follows:

[0019] When natural gas is injected into the blast furnace, the waste heat of the high-temperature flue gas in the hot blast stove is used to heat the natural gas before it enters the blast furnace directly, reducing the number of energy conversions and improving energy utilization efficiency. Furthermore, the amount of hot blast stove flue gas consumed can be automatically adjusted according to the actual amount of natural gas injected into the blast furnace, enabling fully automatic operation without the need for additional operators.

[0020] 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

[0021] 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:

[0022] Figure 1 This is a schematic diagram of the blast furnace natural gas injection heating system of this utility model.

[0023] Figure label:

[0024] 1 Blast furnace, 2 Hot blast stove, 3 High-temperature flue gas duct, 4 Thermometer, 5 First flue gas duct, 6 Flow regulating valve, 7 Flow meter, 8 Heat exchanger, 9 Third flue gas duct, 10 Thermometer, 11 Flow regulating valve, 12 Flow regulating valve, 13 Waste heat recovery device, 14 Second flue gas duct, 15 Chimney, 16 Flow regulating valve, 17 Thermometer, 18 Flow meter, 19 Second natural gas duct, 20 First natural gas duct, 21 Thermometer, 22 Flow regulating valve, 23 Second natural gas inlet, 24 Low-temperature natural gas pipeline, 25 First natural gas inlet, 26 Natural gas outlet, 27 Flue gas inlet, 28 Flue gas outlet. Detailed Implementation

[0025] 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.

[0026] 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.

[0027] 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.

[0028] Please see Figure 1 This is a blast furnace natural gas injection heating system, comprising a hot blast stove 2 that generates high-temperature flue gas, and a blast furnace 1 connected to the hot blast stove 2 via a heat exchanger 8. The heat exchanger 8 is equipped with a first natural gas inlet 25, a natural gas outlet 26, a flue gas inlet 27, and a flue gas outlet 28. The hot blast stove 2 is connected to the flue gas inlet 27 via a first flue gas pipe 5, and the blast furnace 1 is connected to the natural gas outlet 26 via a first natural gas pipe 20. High-temperature flue gas enters the heat exchanger 8 through the flue gas inlet 27, and the natural gas before heating enters through the first natural gas inlet 25 for heat exchange. The heated natural gas is then transported to the blast furnace 1 via the first natural gas pipe 20.

[0029] The heating gas source is taken from the high-temperature flue gas generated by the hot blast stove 2, and the gas being heated is natural gas. The high-temperature flue gas generated by the hot blast stove 2 exchanges heat with the natural gas that will be blown into the blast furnace 1 in the heat exchanger 8, so that the low-temperature natural gas is heated into high-temperature natural gas, reducing the number of energy conversions and improving energy utilization efficiency.

[0030] A high-temperature flue gas duct 3 is installed on the hot blast stove 2. The end of the high-temperature flue gas duct 3 away from the hot blast stove 2 is connected to a second flue gas duct 14 and a first flue gas duct 5, respectively. The end of the second flue gas duct 14 away from the high-temperature flue gas duct 3 is connected to a chimney 15. The high-temperature flue gas from the hot blast stove 2 can be transported to the heat exchanger 8 through the first flue gas duct 5, or it can be transported to the chimney 15 and discharged through the second flue gas duct 14.

[0031] A thermometer 4 is installed on the high-temperature flue gas duct 3 to measure the initial temperature of the high-temperature flue gas; a flow regulating valve 6 and a flow meter 7 are installed sequentially on the first flue gas duct 5 to adjust and measure the flow rate of the high-temperature flue gas entering the heat exchanger 8.

[0032] A waste heat recovery device 13 is installed on the second flue gas duct 14; the high-temperature flue gas flowing through the second flue gas duct 14 undergoes waste heat recovery in the waste heat recovery device 13.

[0033] A flow regulating valve 12 is installed on the second flue gas duct 14 located between the waste heat recovery device 13 and the hot air furnace 2 to adjust the flow rate of high-temperature flue gas through the second flue gas duct 14 and the waste heat recovery device 13.

[0034] The first natural gas inlet 25 is connected to the cryogenic natural gas pipeline network 24 via the second natural gas pipeline 19, and the natural gas entering the second natural gas pipeline 19 originates from the cryogenic natural gas pipeline network 24.

[0035] A thermometer 21 and a flow regulating valve 22 are sequentially installed on the first natural gas pipeline 20. The thermometer 21 is used to measure the temperature of the natural gas after it has been heated, and the flow regulating valve 22 is used to adjust the flow rate of the natural gas entering the blast furnace 1. A flow regulating valve 16, a flow meter 17, and a thermometer 18 are sequentially installed on the second natural gas pipeline 19. The flow regulating valve 16 is used to adjust the flow rate of the low-temperature natural gas entering the heat exchanger 8, the flow meter 17 is used to measure the flow rate of the low-temperature natural gas entering the heat exchanger 8, and the thermometer 18 is used to measure the temperature of the low-temperature natural gas before it is heated.

[0036] The flue gas outlet 28 is connected to the chimney 15 through the third flue gas duct 9. The high-temperature flue gas, after heat exchange in the heat exchanger 8, is discharged from the flue gas outlet 28, and then through the third flue gas duct 9 until it is discharged from the chimney 15.

[0037] A thermometer 10 and a flow regulating valve 11 are sequentially installed on the third flue gas duct 9. The thermometer 10 is used to measure the temperature of the high-temperature flue gas after heat exchange, and the flow regulating valve 11 is used to regulate the flow rate of the flue gas discharged through the third flue gas duct 9.

[0038] It also has a central control system that is electrically connected to each thermometer, flow regulating valve, and flow meter.

[0039] The flow regulating valves 16 and 7 installed on the second natural gas pipeline 19 and the first flue gas pipeline 5, respectively, can be adjusted to open or close depending on whether the heat exchanger 8 needs maintenance.

[0040] Figure 1 The dashed line in the middle indicates the flue gas route of the conventional hot blast stove. That is, the high-temperature flue gas generated by the hot blast stove 2 is used by the waste heat recovery device 13 after passing through the high-temperature flue gas pipe 3, and then discharged after passing through the flue gas pipe 14 and the chimney 15.

[0041] The entire system is installed on the natural gas injection pipeline of blast furnace 2. The second natural gas pipeline 19 is connected to the natural gas inlet of heat exchanger 8. The natural gas outlet of heat exchanger 8 is connected to the second natural gas air inlet 23 on the blast furnace via the second natural gas pipeline 20. A thermometer is installed on the second natural gas pipeline 19 to measure the natural gas temperature. A flow regulating valve 16 and a flow meter 18 are also installed on the second natural gas pipeline 19 to regulate the natural gas flow. A flow regulating valve 22 is installed on the second natural gas pipeline 20 after the outlet of heat exchanger 8 to regulate the natural gas flow. A thermometer 21 is installed on the second natural gas pipeline 20 after the outlet of heat exchanger 8 to measure the temperature of the heated natural gas.

[0042] A first flue gas duct 5 is led out from the high-temperature flue gas duct 3 and connected to the flue gas inlet 27 of the heat exchanger 8. A third flue gas duct 9 is set after the flue gas outlet 28 on the heat exchanger 8, which merges into the second flue gas duct 14 and is then discharged through the chimney 15. A thermometer 4 is installed on the high-temperature flue gas duct 3 to measure the temperature of the high-temperature flue gas, and a flow regulating valve 12 is installed to regulate the flue gas flow. A flow regulating valve 6 and a flow meter 7 are installed on the newly added first flue gas duct 5, and a flow regulating valve 11 is installed on the third flue gas duct 9 to regulate the flue gas flow. A thermometer 10 is installed on the third flue gas duct 9 to measure the temperature of the flue gas after heat exchange.

[0043] A flow regulating valve 22 is installed on the first natural gas pipeline 20, and a flow regulating valve 11 is installed on the third flue gas pipeline 9 to facilitate the maintenance of the heat exchanger; a thermometer 21 is installed on the first natural gas pipeline 20 to measure the temperature of the heated natural gas; a thermometer 10 is installed on the third flue gas pipeline 9 to measure the temperature of the flue gas after heat exchange; the opening of the flow regulating valves on the flue gas pipelines is controlled by the central control system, and can be automatically set by a computer program according to the needs of natural gas heating, or can be manually set by production experience.

[0044] The control method of the blast furnace natural gas injection heating system of this utility model is as follows:

[0045] When the blast furnace injects natural gas, the natural gas heating operation is started; when the blast furnace stops injecting natural gas, the natural gas heating operation is stopped.

[0046] The specific control methods for natural gas heating operations are as follows:

[0047] S1, When natural gas is injected into the blast furnace, the central control system determines that the natural gas in the blast furnace needs to be heated;

[0048] S2, the central control system calculates the blast furnace natural gas flow rate to be heated and the hot blast stove high-temperature flue gas flow rate to be provided based on the blast furnace natural gas temperature and flow rate measured by thermometer 17 and flow meter 18 on the blast furnace natural gas pipeline 19 and the hot blast stove high-temperature flue gas temperature measured by thermometer 4 on the high-temperature flue gas pipeline 3.

[0049] S3, open the flow regulating valve 6 on the first flue gas duct 5 before the heat exchanger 8 and the flow regulating valve 11 on the third flue gas duct 9 after the heat exchanger 8, and at the same time, appropriately close the flow regulating valve 12 on the second flue gas duct 14 before the waste heat recovery device 13, so that the data measured by the flow meter 7 on the first flue gas duct 5 before the heat exchanger 8 is the same as the calculated required hot blast stove flue gas flow. The high temperature hot blast stove flue gas enters the flue gas inlet 27 of the heat exchanger 8, and after heat exchange in the heat exchanger 8, the flue gas flows through the third flue gas duct 9 into the second flue gas duct 14 after the waste heat recovery device 13 and is discharged through the chimney 15.

[0050] S4, open the flow regulating valves 16 and 22 on the second natural gas pipeline 19 and the first natural gas pipeline 20 respectively, so that the flow data measured by the flow meter 18 is the same as the flow rate of the natural gas to be injected. The low temperature natural gas flows to the first natural gas inlet 25 of the heat exchanger 8 heated by the high temperature flue gas, and is then heated by the heat exchanger 8. The heated blast furnace injection natural gas enters the blast furnace 1 through the second natural gas inlet 23.

[0051] When the natural gas heating operation is stopped, i.e. when the blast furnace does not require natural gas injection, the reverse procedure of the natural gas heating operation is executed. The specific control method is as follows:

[0052] S1, close the flow regulating valves 16 and 22 on the natural gas pipeline;

[0053] S2, close the flue gas flow regulating valves 6 and 11 on the flue gas duct, and at the same time fully open the flow regulating valve 12 on the second flue gas duct 14 before the waste heat recovery device 13, so that all the flue gas from the hot blast stove is discharged from the hot blast stove chimney 15 after passing through the waste heat recovery device 13.

[0054] The opening and closing or the degree of opening of the flow regulating valves on natural gas pipelines and flue gas pipelines are automatically controlled by the central control system according to the needs of natural gas heating, or they can be manually set according to production experience.

[0055] 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 blast furnace natural gas injection heating system, characterized in that: The system includes a hot blast stove (2) that generates high-temperature flue gas, and a blast furnace (1) connected to the hot blast stove (2) via a heat exchanger (8). The heat exchanger (8) is provided with a first natural gas inlet (25), a natural gas outlet (26), a flue gas inlet (27), and a flue gas outlet (28). The hot blast stove (2) is connected to the flue gas inlet (27) via a first flue gas pipe (5), and the blast furnace (1) is connected to the natural gas outlet (26) via a first natural gas pipe (20). The high-temperature flue gas enters the heat exchanger (8) via the flue gas inlet (27), and the natural gas before heating enters the heat exchanger (8) via the first natural gas inlet (25) for heat exchange. The heated natural gas is then transported to the blast furnace (1) via the first natural gas pipe (20).

2. The blast furnace natural gas injection heating system according to claim 1, characterized in that: The hot air furnace (2) is provided with a high-temperature flue gas pipe (3), and the end of the high-temperature flue gas pipe (3) away from the hot air furnace (2) is connected to the second flue gas pipe (14) and the first flue gas pipe (5) respectively; the end of the second flue gas pipe (14) away from the high-temperature flue gas pipe (3) is connected to the chimney (15).

3. The blast furnace natural gas injection heating system according to claim 2, characterized in that: A thermometer (4) is installed on the high-temperature flue gas pipeline (3); a flow regulating valve (6) and a flow meter (7) are installed in sequence on the first flue gas pipeline (5); a thermometer (21) and a flow regulating valve (22) are installed in sequence on the first natural gas pipeline (20).

4. The blast furnace natural gas injection heating system according to claim 3, characterized in that: The second flue gas duct (14) is equipped with a waste heat recovery device (13).

5. The blast furnace natural gas injection heating system according to claim 4, characterized in that: A flow regulating valve (12) is installed on the second flue gas duct (14) located between the waste heat recovery device (13) and the hot air furnace (2).

6. The blast furnace natural gas injection heating system according to claim 2, characterized in that: The first natural gas inlet (25) is connected to the low-temperature natural gas pipeline network (24) through the second natural gas pipeline (19).

7. The blast furnace natural gas injection heating system according to claim 6, characterized in that: The second natural gas pipeline (19) is equipped with a flow regulating valve (16), a flow meter (18) and a thermometer (17) in sequence.

8. The blast furnace natural gas injection heating system according to claim 7, characterized in that: The flue gas outlet (28) is connected to the chimney (15) through the third flue gas duct (9).

9. The blast furnace natural gas injection heating system according to claim 8, characterized in that: A thermometer (10) and a flow regulating valve (11) are sequentially installed on the third flue gas duct (9).

10. The blast furnace natural gas injection heating system according to any one of claims 5 or 9, characterized in that: It also has a central control system that is electrically connected to each thermometer, flow regulating valve, and flow meter.

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