Heat exchange device and method for coal injection system

Abstract

The present invention provides a heat exchange device and method for a coal injection system, comprising a drying furnace, an exhaust flue gas pipe, an exhaust flue gas inlet, an exhaust flue gas outlet, a heat exchange pipe group, a steam inlet, a coal injection pipe group, and a switching component. The exhaust flue gas pipe is used to transport exhaust flue gas to the drying furnace; the heat exchange pipe group is connected to the exhaust flue gas pipe through the exhaust flue gas inlet and the exhaust flue gas outlet; the steam inlet is arranged near the exhaust flue gas inlet of the heat exchange pipe group; the heat exchange pipe group is used to heat the compressed gas in the coal injection pipe group; the switching component is arranged near the exhaust flue gas outlet of the heat exchange pipe group, and the switching component is used to discharge gas and / or liquid while preventing gas from entering the drying furnace through the exhaust flue gas outlet and the exhaust flue gas pipe. Different gases can be selected to heat the compressed gas, thereby improving the adaptability of the coal injection system heat exchange device to different situations.

Description

Technical Field

[0001] The present invention relates to the field of heating equipment, and in particular to a heat exchange device and method for a coal injection system. Background Art

[0002] Pulverized coal in blast furnace ironmaking coal injection systems is primarily transported to the blast furnace via injection tanks and pipelines using compressed gas as the conveying medium. In actual production, this process results in significant heat loss. This is primarily due to the relatively low temperature of the compressed gas used for transporting the pulverized coal. After mixing with the pulverized coal, it removes a significant amount of heat from the pulverized coal. Currently, factories use heated exhaust gas to heat the compressed gas, effectively utilizing existing resources and improving energy efficiency.

[0003] However, the amount of heat carried by exhaust flue gas is currently difficult to estimate, and to improve energy efficiency, the exhaust flue gas used for heating is introduced into the drying furnace after heating the compressed gas, where the heat in the exhaust flue gas is used to dry the material in the drying furnace. However, after the exhaust gas heats the compressed gas, the drying furnace's heat requirements may not be met, which can seriously affect the drying effect of the drying furnace. In severe cases, this can affect subsequent processing steps and may even require the resumption of the drying process or subsequent steps, resulting in unnecessary cost losses. Summary of the Invention

[0004] In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a coal injection system heat exchange device and method for solving the problem in the prior art that after the waste flue gas heats the compressed gas, the heat in the waste flue gas is sometimes unable to meet the heat requirement of the drying furnace.

[0005] To achieve the above-mentioned and other related purposes, the present invention provides a heat exchange device for a coal injection system, comprising:

[0006] drying oven;

[0007] a waste flue gas duct, the waste flue gas duct being used to transport waste flue gas to the drying furnace;

[0008] a waste smoke inlet and a waste smoke outlet, wherein the waste smoke inlet and the waste smoke outlet are both arranged on the waste smoke duct;

[0009] a heat exchange pipe group, wherein the heat exchange pipe group is connected to the waste flue gas pipe through the waste flue gas inlet and the waste flue gas outlet;

[0010] A steam inlet is provided at the heat exchange pipe group near the exhaust gas inlet;

[0011] A coal injection pipeline group, wherein the heat exchange pipeline group is used to heat the compressed gas in the coal injection pipeline group;

[0012] a switching component, the switching component being arranged at the heat exchange pipe group near the exhaust gas outlet, the switching component being used to discharge gas and / or liquid while preventing gas from entering the drying furnace through the exhaust gas outlet and the exhaust gas pipe;

[0013] Wherein, the waste gas inlet and the steam inlet are both provided with switch valves.

[0014] Optionally, the switching assembly includes a drain pipe, a drain valve arranged on the drain pipe, a vent, a vent valve and a stop valve arranged on the vent, the vent is used to release gas, the drain pipe is used to discharge steam water after steam condensation, and the stop valve is used to prevent gas from passing through the heat exchange pipe group into the waste flue gas pipe.

[0015] Optionally, the waste flue gas is blast furnace hot blast stove waste gas.

[0016] Optionally, a first thermometer and a first regulating valve for adjusting the air volume of the blast furnace hot blast stove exhaust gas are provided at the exhaust outlet of the blast furnace hot blast stove exhaust gas.

[0017] Optionally, a second temperature gauge and the first induced draft fan are provided at the gas inlet of the drying furnace.

[0018] Optionally, a second regulating valve is provided on the heat exchange pipe group near the waste gas inlet.

[0019] Optionally, a second induced draft fan is further provided near the exhaust gas inlet of the heat exchange pipe group, and along the flow direction of the gas, the second regulating valve, the second induced draft fan and the switch valve are sequentially spaced apart.

[0020] The present invention provides a heat exchange method for a coal injection system, comprising:

[0021] Providing the coal injection system heat exchange device as described above;

[0022] Measure the temperature value at the exhaust gas outlet;

[0023] Based on the temperature value, determining heating gas for heating compressed gas in the heat exchange device of the coal injection system;

[0024] According to the heating gas, the states of the switch valves and the switching components are adjusted so that the heating gas enters the heat exchange pipe group, flows along a preset route and heats the compressed gas;

[0025] The pulverized coal is sprayed using heated compressed gas.

[0026] In one embodiment of the present invention, determining the heating gas for heating the compressed gas in the heat exchange device of the coal injection system based on the temperature value includes:

[0027] When the temperature is greater than or equal to 160 degrees Celsius, the exhaust gas is used as the heating gas;

[0028] When the temperature is less than 160 degrees Celsius, steam is used as the heating gas.

[0029] In one embodiment of the present invention, adjusting the states of the switch valves and the switching components according to the heated gas includes:

[0030] If the heating gas is steam, close the vent valve and the on-off valve at the exhaust gas inlet, and open the drain valve and the on-off valve at the steam inlet;

[0031] If the heating gas is waste flue gas, open the bleed valve and the on-off valve at the waste flue gas inlet, the second regulating valve, and the second induced draft fan, and close the drain valve, the bleed valve, and the on-off valve at the steam inlet. The waste flue gas dries the inner wall of the heat exchange pipe group. After drying is completed, close the bleed valve and open the stop valve.

[0032] As described above, a heat exchange device and method for a coal injection system of the present invention has the following beneficial effects: by setting a waste flue gas inlet, a steam inlet and a switching component, when heating the compressed gas, it can be determined whether to use the waste flue gas to heat the compressed gas based on the temperature of the waste flue gas. When the waste flue gas heats the compressed gas and it is difficult to meet the drying temperature of the drying furnace, steam can be selected to heat the compressed gas, which increases the ways for the heat exchange device of the coal injection system to heat the compressed gas. When heating the compressed gas, the adaptability of the heat exchange device of the coal injection system to different situations is improved. And by setting a steam inlet, the heat in the steam can also be reasonably utilized. While ensuring production requirements, energy is reasonably utilized, achieving the purpose of energy recycling and energy conservation, emission reduction and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Shown is a structural schematic diagram of a heat exchange device of a coal injection system according to an embodiment of the present invention.

[0034] Explanation of reference numbers: 1. Drying furnace; 2. Second thermometer; 3. First induced draft fan; 4. Waste flue gas outlet; 5. Waste flue gas duct; 6. Waste flue gas inlet; 7. First regulating valve; 8. First thermometer; 9. Second regulating valve; 10. Second induced draft fan; 11. On-off valve; 12. Steam inlet; 13. Heat exchange pipe group; 14. Injection main pipe; 15. Gas distribution bag; 16. Vent; 17. Vent valve; 18. Stop valve; 19. Drain valve; 20. Drain pipe. DETAILED DESCRIPTION

[0035] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0036] See also Figure 1 It should be noted that the diagrams provided in this embodiment are only schematic illustrations of the basic concept of the present invention. Therefore, the diagrams only show the components related to the present invention and are not drawn according to the number, shape and size of the components in actual implementation. The type, quantity and proportion of each component in actual implementation can be changed at will, and the component layout type may also be more complex. The structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read. They are not used to limit the limiting conditions for the implementation of the present invention and therefore have no technical significance. Any modification of the structure, change in the proportional relationship or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the efficacy and purpose that can be achieved by the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description and are not used to limit the scope of the implementation of the present invention. Changes or adjustments in their relative relationships should also be considered as the scope of the implementation of the present invention without substantially changing the technical content.

[0037] See Figure 1The present invention provides a heat exchange device for a coal injection system, comprising a drying furnace 1, a waste flue gas pipe 5, a waste flue gas inlet 6, a waste flue gas outlet 4, a heat exchange pipe group 13, a steam inlet 12, a coal injection pipe group and a switching component; the waste flue gas pipe 5 is used to transport waste flue gas to the drying furnace 1; the waste flue gas inlet 6 and the waste flue gas outlet 4 are both arranged on the waste flue gas pipe 5; the heat exchange pipe group 13 is connected to the waste flue gas pipe 5 through the waste flue gas inlet 6 and the waste flue gas outlet 4; the steam inlet 12 is arranged at the heat exchange pipe group 13 near the waste flue gas inlet 6; the heat exchange pipe group 13 is used to heat the compressed gas in the coal injection pipe group; the switching component is arranged at the heat exchange pipe group 13 near the waste flue gas outlet 4, the switching component is used to discharge gas and / or liquid, and at the same time prevent gas from entering the drying furnace 1 through the waste flue gas outlet 4 and the waste flue gas pipe 5; wherein, a switch valve 11 is provided at both the waste flue gas inlet 6 and the steam inlet 12. By providing a waste flue gas inlet 6 and a steam inlet 12 and a switching component, the coal injection system heat exchanger can select waste flue gas or steam as the heating gas for heating the compressed gas when heating the compressed gas. The heating gas used to heat the compressed gas can be flexibly adjusted based on the heat requirement of the drying furnace 1 for the waste flue gas. In this embodiment, the compressed gas is nitrogen. In some embodiments, the compressed gas can be compressed air. In this embodiment, the coal injection system heat exchanger is used in a steel mill, which has a large amount of waste flue gas and steam. Waste flue gas is the flue gas with heat generated during combustion. Steam is a by-product in steel manufacturing, produced by evaporating water from waste heat during the steel production process. Waste flue gas and steam are both the first choice for factories to heat and keep materials warm.

[0038] The switching assembly includes a drain pipe 20, a drain valve 19 mounted on the drain pipe 20, a vent 16, a vent valve 17 mounted on the vent 16, and a shutoff valve 18. The vent 16 is used to release gas, the drain pipe 20 is used to drain condensed steam water, and the shutoff valve 18 is used to prevent gas from entering the exhaust flue gas duct 5 through the heat exchange pipe assembly 13. When steam heats the compressed gas in the heat exchange pipe assembly 13, it condenses into a liquid, which can then be discharged from the heat exchange pipe assembly 13 through the drain pipe 20. Since the heat exchange pipe assembly 13 is connected to the drying furnace 1 via the exhaust flue gas outlet 4 and the exhaust flue gas duct 5, and moisture cannot enter the drying furnace 1 during the material drying process, when steam is used to heat the compressed gas in the heat exchange pipe assembly 13, the shutoff valve 18 is required to prevent steam from entering the drying furnace 1 through the exhaust flue gas outlet 4 and the exhaust flue gas duct 5, thereby affecting the drying efficiency of the drying furnace 1. The condensed water is then discharged into the pipes through the drain valve 19. In this embodiment, the drying furnace 1 is used to dry the coal used in the blast furnace. The above-mentioned coal is ground into the pulverized coal required for the blast furnace ironmaking coal injection system by a coal mill. In this embodiment, the exhaust gas is the exhaust gas from the blast furnace hot blast furnace. When steam is used to heat the compressed gas, the steam will condense on the inner wall of the heat exchange pipe group 13 to form water droplets. When the heating gas in the heat exchange pipe group 13 is switched from steam to exhaust gas, in order to ensure that the water vapor in the heat exchange pipe group 13 does not enter the drying furnace 1, it is necessary to close the drain valve 19 and the switch valve 11 at the steam inlet 12, open the switch valve 11 at the exhaust gas inlet 6, open the vent valve 17, confirm that the stop valve 18 is still in the closed state, introduce the exhaust gas into the heat exchange pipe group 13, and dry the inner wall of the heat exchange pipe group 13.

[0039] Specifically, a first thermometer 8 and a first regulating valve 7 for adjusting the air volume of the blast furnace hot blast furnace exhaust gas are provided at the exhaust outlet of the blast furnace hot blast furnace. A second thermometer 2 and a first induced draft fan 3 are provided at the gas inlet of the drying furnace 1. The first thermometer 8 can monitor the temperature of the blast furnace hot blast furnace exhaust gas as it flows out, and the second thermometer 2 can monitor the temperature of the blast furnace hot blast furnace exhaust gas as it flows out. By detecting these temperatures, the first regulating valve 7 can be used to adjust the air volume of the blast furnace hot blast furnace exhaust gas as it flows out. The first induced draft fan 3 can increase the flow rate of the exhaust gas in the exhaust gas pipe to prevent the exhaust gas from losing a large amount of heat due to its slow flow rate during the process of flowing into the drying furnace 1. In this embodiment, the temperature value on the first thermometer 8 is used as a standard, and exhaust gas or steam is selected as the heating gas to enter the heat exchange pipe group 13 to heat the compressed gas. When the temperature on the first thermometer 8 is greater than or equal to 160 degrees Celsius, exhaust gas is used as the heating gas; when the temperature on the first thermometer 8 is less than 160 degrees Celsius, steam is used as the heating gas. These temperature settings can be adjusted based on actual production conditions. In this embodiment, the coal injection pipeline assembly includes a compressed gas distribution bag 15 and an injection main pipe 14. By heating and insulating the compressed gas distribution bag 15 and the injection main pipe 14, the temperature of the compressed gas is raised and maintained, thereby reserving sufficient heat for the subsequent injection of pulverized coal.

[0040] Specifically, a second regulating valve 9 is provided near the exhaust gas inlet 6 of the heat exchange pipe group 13. A second induced draft fan 10 is also provided near the exhaust gas inlet 6 of the heat exchange pipe group 13. The second regulating valve 9, the second induced draft fan 10, and the switch valve 11 are sequentially spaced along the direction of gas flow. The second regulating valve 9 can be used to adjust the amount of exhaust gas entering the heat exchange pipe group 13 based on the temperature values ​​displayed on the first thermometer 8 and the second thermometer 2, facilitating regulation and ensuring that the heat carried by the exhaust gas entering the drying furnace 1 meets the production needs of the drying furnace 1. The second regulating valve 9, the second induced draft fan 10, and the switch valve 11 are discharged sequentially, which can reduce wear on the regulating valves during use and protect the regulating valves at the first inlet.

[0041] The present invention provides a heat exchange method for a coal injection system, comprising providing a heat exchange device for the coal injection system as described above; measuring a temperature value at an exhaust gas outlet; determining, based on the temperature value, a heating gas for heating compressed gas in the heat exchange device for the coal injection system; adjusting the states of each switch valve 11 and a switching component according to the heating gas so that the heating gas enters a heat exchange pipe group 13, flows along a preset route, and heats the compressed gas; and using the heated compressed gas to inject pulverized coal.

[0042] In one embodiment of the present invention, the heating gas used to heat the compressed gas in the coal injection system heat exchange device is determined based on the temperature value, including: when the temperature value is greater than or equal to 160 degrees Celsius, exhaust gas is used as the heating gas; when the temperature value is less than 160 degrees Celsius, steam is used as the heating gas.

[0043] In one embodiment of the present invention, the states of the various on-off valves 11 and switching components are adjusted based on the heating gas. This includes: if the heating gas is steam, the on-off valve 11 and the bleed valve 17 at the exhaust gas inlet 6 are closed, while the drain valve 19 and the on-off valve 11 at the steam inlet 12 are opened. If the heating gas is exhaust gas, the bleed valve 17, the on-off valve 11 at the exhaust gas inlet 6, the second regulating valve 9, and the second induced draft fan 10 are opened, while the drain valve 19, the bleed valve 17, and the on-off valve 11 at the steam inlet 12 are closed. The exhaust gas dries the inner wall of the heat exchange pipe group 13. After drying is complete, the bleed valve 17 is closed and the shut-off valve 18 is opened. In this embodiment, the drying time is five minutes, which can be adjusted based on the actual pipeline length and layout. This drying process prevents any remaining water vapor from being discharged into the drying furnace 1, thereby affecting the drying effect of the pulverized coal.

[0044] In summary, by providing the exhaust gas inlet 6 and the steam inlet 12, a suitable heating gas can be selected to heat the compressed gas, ensuring that the quality of the subsequently produced products can be guaranteed after the first gas or the second gas has heated the compressed gas. If, during the process of fully utilizing the first gas or the second gas, the first gas or the second gas fails to meet subsequent production requirements after heating the compressed gas, another backup gas can be used to heat the compressed gas, thereby avoiding the problem of insufficient inherent heat in the gas, which could result in difficulty in ensuring the quality of the subsequently produced products after heating the compressed gas.

[0045] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A heat exchange device for a coal injection system, characterized in that: include: drying oven; a waste flue gas duct, the waste flue gas duct being used to transport waste flue gas to the drying furnace; a waste smoke inlet and a waste smoke outlet, wherein the waste smoke inlet and the waste smoke outlet are both arranged on the waste smoke duct; a heat exchange pipe group, the heat exchange pipe group being connected to the exhaust gas pipe through the exhaust gas inlet and the exhaust gas outlet; a steam inlet, the steam inlet being arranged at the heat exchange pipe group near the exhaust gas inlet; A coal injection pipeline group, wherein the heat exchange pipeline group is used to heat the compressed gas in the coal injection pipeline group; a switching component, the switching component being arranged at the heat exchange pipe group near the exhaust gas outlet, the switching component being used to discharge gas and / or liquid while preventing gas from entering the drying furnace through the exhaust gas outlet and the exhaust gas pipe; Wherein, the waste gas inlet and the steam inlet are both provided with switch valves.

2. The heat exchange device for coal injection system according to claim 1, characterized in that: The switching assembly includes a drain pipe, a drain valve arranged on the drain pipe, a vent, a vent valve and a stop valve arranged on the vent. The vent is used to release gas, the drain pipe is used to discharge steam water after steam condensation, and the stop valve is used to prevent gas from passing through the heat exchange pipe group into the waste flue gas pipe.

3. The heat exchange device of the coal injection system according to claim 2, characterized in that: The waste flue gas is blast furnace hot blast stove waste gas.

4. The heat exchange device for coal injection system according to claim 3, characterized in that: A first thermometer and a first regulating valve for regulating the air volume of the blast furnace hot blast stove exhaust gas are provided at the exhaust outlet of the blast furnace hot blast stove exhaust gas.

5. The heat exchange device for coal injection system according to claim 3, characterized in that: A second temperature gauge and a first induced draft fan are provided at the gas inlet of the drying furnace.

6. The heat exchange device for coal injection system according to claim 2, characterized in that: The heat exchange pipe group is provided with a second regulating valve near the waste gas inlet.

7. The heat exchange device for coal injection system according to claim 6, characterized in that: The heat exchange pipe group is further provided with a second induced draft fan near the exhaust gas inlet. Along the flow direction of the gas, the second regulating valve, the second induced draft fan and the switch valve are sequentially spaced apart.

8. A heat exchange method for a coal injection system, characterized in that: include: Providing a coal injection system heat exchange device according to claim 7; Measure the temperature value at the exhaust gas outlet; Based on the temperature value, determining heating gas for heating compressed gas in the heat exchange device of the coal injection system; According to the heating gas, the states of the switch valves and the switching components are adjusted so that the heating gas enters the heat exchange pipe group, flows along a preset route and heats the compressed gas; The pulverized coal is sprayed using heated compressed gas.

9. The heat exchange method of coal injection system according to claim 8, characterized in that: Determining, based on the temperature value, heating gas for heating the compressed gas in the heat exchange device of the coal injection system, comprising: When the temperature is greater than or equal to 160 degrees Celsius, the exhaust gas is used as the heating gas; When the temperature is less than 160 degrees Celsius, steam is used as the heating gas.

10. The heat exchange method of coal injection system according to claim 8, characterized in that: According to the heated gas, the states of the various switch valves and switching components are adjusted, including: If the heating gas is steam, close the vent valve and the on-off valve at the exhaust gas inlet, and open the drain valve and the on-off valve at the steam inlet; If the heating gas is waste flue gas, open the bleed valve and the on-off valve at the waste flue gas inlet, the second regulating valve, and the second induced draft fan, and close the drain valve, the bleed valve, and the on-off valve at the steam inlet. The waste flue gas dries the inner wall of the heat exchange pipe group. After drying is completed, close the bleed valve and open the stop valve.

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