Converter venting gas recycling system

Abstract

This invention discloses a converter vent gas recovery and utilization system, relating to the field of energy recovery technology. The system connects the flue gas inlet of a gas heater to the flue gas outlet of a low-temperature molten salt furnace, and the gas outlet of the gas heater to the gas inlet of a burner. The burner heats the high-temperature molten salt furnace and generates flue gas. The flue gas outlet of the high-temperature molten salt furnace is connected to the flue gas inlet of the low-temperature molten salt furnace. The molten salt outlet of the high-temperature molten salt furnace is connected to the molten salt inlet of a high-temperature molten salt tank. The molten salt outlet of the high-temperature molten salt tank is connected to both the molten salt inlet of the high-temperature molten salt furnace and the molten salt inlet of a molten salt heat exchanger. The molten salt outlet of the molten salt heat exchanger is connected to the molten salt inlet of the low-temperature molten salt tank, and the molten salt outlet of the low-temperature molten salt tank is connected to the molten salt inlet of the low-temperature molten salt furnace. The molten salt outlet of the low-temperature molten salt furnace is connected to both the molten salt inlet of the low-temperature molten salt tank and the molten salt inlet of the high-temperature molten salt furnace. This invention can improve the utilization rate of converter gas, save energy and reduce emissions, and improve economic efficiency.

Description

Technical Field

[0001] This invention relates to the field of energy recovery technology, specifically to a converter vent gas recovery and utilization system. Background Technology

[0002] Although the recovery rate of converter gas in steel plants across the country is gradually increasing, a certain amount of converter gas is still released due to reasons such as low recovery technology precision or full gas holders. Moreover, the calorific value of converter gas is relatively high. Therefore, the waste heat and energy loss caused by the inability to recover converter gas each year is quite staggering. If its calorific value can be recovered and utilized, it will generate considerable economic benefits. Summary of the Invention

[0003] The purpose of this invention is to provide a converter vent gas recovery and utilization system to solve the problems existing in the prior art, thereby improving the utilization rate of converter gas, saving energy and reducing emissions, and improving economic benefits.

[0004] To achieve the above objectives, the present invention provides the following solution:

[0005] This invention provides a converter vent gas recovery and utilization system, including a high-temperature molten salt furnace, a high-temperature molten salt ladle, a low-temperature molten salt furnace, a low-temperature molten salt ladle, a gas heater, a burner, and a molten salt heat exchanger. The flue gas inlet of the gas heater is connected to the flue gas outlet of the low-temperature molten salt furnace. The gas inlet of the gas heater is used for the gas to be treated to enter. The gas outlet of the gas heater is connected to the gas inlet of the burner. The burner is used to heat the inside of the high-temperature molten salt furnace and generate flue gas. The air inlet of the burner is connected to the outside. The flue gas outlet is connected to the flue gas inlet of the low-temperature molten salt furnace, the molten salt outlet of the high-temperature molten salt furnace is connected to the molten salt inlet of the high-temperature molten salt tank, the molten salt outlet of the high-temperature molten salt tank is connected to the molten salt inlet of the high-temperature molten salt furnace and the molten salt inlet of the molten salt heat exchanger, the molten salt outlet of the molten salt heat exchanger is connected to the molten salt inlet of the low-temperature molten salt tank, the molten salt outlet of the low-temperature molten salt tank is connected to the molten salt inlet of the low-temperature molten salt furnace, and the molten salt outlet of the low-temperature molten salt furnace is connected to the molten salt inlet of the low-temperature molten salt tank and the molten salt inlet of the high-temperature molten salt furnace.

[0006] Preferably, the gas inlet of the gas heater is connected to a converter vent gas storage device.

[0007] Preferably, the flue gas outlet of the gas heater is sequentially connected to a flue gas regulating valve, an induced draft fan, and a chimney.

[0008] Preferably, it further includes an air preheater, wherein the air inlet of the air preheater is connected to the outside, the air outlet of the air preheater is connected to the air inlet of the burner, the flue gas inlet of the air preheater is connected to the flue gas outlet of the low-temperature molten salt furnace, and the flue gas outlet of the air preheater is connected to the flue gas inlet of the gas heater.

[0009] Preferably, the lower end of the high-temperature molten salt tank is provided with a high-temperature electric heater, the heating temperature range of which is 400℃~600℃; the lower end of the low-temperature molten salt tank is provided with a low-temperature electric heater, the heating temperature range of which is 250℃~350℃.

[0010] Preferably, a high-temperature molten salt pump is provided between the molten salt outlet of the high-temperature molten salt tank and the molten salt inlet of the high-temperature molten salt furnace, a molten salt circulation pump is provided between the molten salt outlet of the high-temperature molten salt tank and the molten salt inlet of the molten salt heat exchanger, and a high-temperature molten salt regulating valve is provided between the molten salt outlet of the high-temperature molten salt furnace and the molten salt inlet of the high-temperature molten salt tank.

[0011] Preferably, a low-temperature molten salt pump is provided between the molten salt outlet of the low-temperature molten salt tank and the molten salt inlet of the low-temperature molten salt furnace, and a low-temperature molten salt regulating valve is provided between the molten salt outlet of the low-temperature molten salt furnace and the molten salt inlet of the high-temperature molten salt furnace.

[0012] Preferably, the molten salt heat exchanger is provided with a water inlet that communicates with the outside, and the steam outlet of the molten salt heat exchanger is connected to the steam inlet of the steam drum.

[0013] Preferably, both the high-temperature molten salt tank and the low-temperature molten salt tank have a heat insulation layer on their side walls.

[0014] The present invention achieves the following technical effects compared to the prior art:

[0015] The converter vent gas recovery and utilization system provided by this invention includes a gas heater with a gas inlet for receiving gas to be treated. The gas heater's flue gas inlet is connected to the flue gas outlet of a low-temperature molten salt furnace, allowing the flue gas from the low-temperature molten salt furnace to be introduced into the gas heater and heated. The heated flue gas is then discharged through the gas heater's flue gas outlet. The gas heater's gas outlet is connected to the burner's gas inlet, allowing the heated gas from the gas heater to be fed into the burner for combustion. The burner heats the high-temperature molten salt furnace and generates flue gas. The burner's air inlet is connected to the outside environment. The high-temperature molten salt furnace's flue gas outlet is connected to the low-temperature molten salt furnace's flue gas inlet, allowing the flue gas generated from the combustion of the mixed gas in the burner to be transported to the low-temperature molten salt furnace for heating. The high-temperature molten salt furnace's molten salt outlet is connected to the high-temperature molten salt tank's molten salt inlet. The heat generated by the burner heats the molten salt in the high-temperature molten salt furnace to a high temperature and then transports it to the high-temperature molten salt tank for storage. The molten salt outlet of the salt tank is connected to the molten salt inlet of the high-temperature molten salt furnace and the molten salt inlet of the molten salt heat exchanger. A portion of the high-temperature molten salt in the high-temperature molten salt tank is transported to the molten salt heat exchanger to exchange heat with the feed water. The water is heated into high-temperature, high-pressure steam and then stored. Another portion of the high-temperature molten salt in the high-temperature molten salt tank is mixed with the low-temperature molten salt transported from the low-temperature molten salt furnace and transported together to the high-temperature molten salt furnace. The molten salt outlet of the molten salt heat exchanger is connected to the molten salt inlet of the low-temperature molten salt tank to transport the heat-exchanged low-temperature molten salt to the low-temperature molten salt tank for storage. The molten salt outlet of the low-temperature molten salt tank is connected to the molten salt inlet of the low-temperature molten salt furnace. The low-temperature molten salt is then heated in the low-temperature molten salt furnace using the high-temperature flue gas transported from the high-temperature molten salt furnace. The molten salt outlet of the low-temperature molten salt furnace is connected to the molten salt inlet of the low-temperature molten salt tank and the molten salt inlet of the high-temperature molten salt furnace. A portion of the low-temperature molten salt in the low-temperature molten salt furnace is transported to the low-temperature molten salt tank for storage, while the other portion is mixed with the high-temperature molten salt in the high-temperature molten salt tank and transported together to the high-temperature molten salt furnace. This invention adds a molten salt heat storage system to the existing equipment in a steel plant. The released coal gas is fed into a burner to heat the molten salt, storing the heat within the salt. The stored heat is then released by heat exchange between the high-temperature molten salt and water, generating high-temperature, high-pressure steam. This not only significantly improves the utilization rate of converter gas but also yields high-quality, high-temperature, high-pressure steam, thus enhancing economic efficiency. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the converter vent gas recovery and utilization system provided by the present invention;

[0018] In the diagram: 1-Low-temperature molten salt tank; 2-Low-temperature electric heater; 3-Low-temperature molten salt pump; 4-Low-temperature molten salt furnace; 5-Low-temperature molten salt regulating valve; 6-High-temperature molten salt furnace; 7-Converter vented gas storage device; 8-Gas heater; 9-Burner; 10-High-temperature molten salt regulating valve; 11-High-temperature molten salt tank; 12-High-temperature electric heater; 13-High-temperature molten salt pump; 14-Molten salt circulation pump; 15-Molten salt heat exchanger; 16-Steam drum; 17-Air preheater; 18-Flue gas regulating valve; 19-Induced draft fan. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] The purpose of this invention is to provide a converter vent gas recovery and utilization system to solve the technical problems of low recovery rate and loss of existing converter vent gas.

[0021] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] like Figure 1As shown, this embodiment provides a converter vent gas recovery and utilization system, including a high-temperature molten salt furnace 6, a high-temperature molten salt tank 11, a low-temperature molten salt furnace 4, a low-temperature molten salt tank 1, a gas heater 8, a burner 9, and a molten salt heat exchanger 15. The flue gas inlet of the gas heater 8 is connected to the flue gas outlet of the low-temperature molten salt furnace 4 to allow the flue gas in the low-temperature molten salt furnace 4 to be introduced into the gas heater 8 and heated. The heat-exchanged flue gas is discharged through the flue gas outlet of the gas heater 8. The gas inlet of the gas heater 8 is used for the gas to be treated. The gas outlet of the gas heater 8 is connected to the gas inlet of the burner 9 to allow the gas to be heated. The heated coal gas is fed into burner 9 for combustion. Burner 9 heats the high-temperature molten salt furnace 6 and generates flue gas. Burner 9 mixes and combusts the converter gas and air in a specific manner, with a combustion temperature range of 1100℃~1300℃. The heat generated by the combustion of the converter gas is used to heat the molten salt to 500℃~600℃. The air inlet of burner 9 is connected to the outside, and the flue gas outlet of high-temperature molten salt furnace 6 is connected to the flue gas inlet of low-temperature molten salt furnace 4. This allows the flue gas generated after the mixed gas in burner 9 is burned to be transported to low-temperature molten salt furnace 4, where the low-temperature molten salt is heated and melted to 250℃~350℃. The molten salt outlet of furnace 6 is connected to the molten salt inlet of high-temperature molten salt tank 11. The heat generated by the combustion of burner 9 heats the molten salt in high-temperature molten salt furnace 6 to a high temperature and then transports it to high-temperature molten salt tank 11 for storage. The molten salt outlet of high-temperature molten salt tank 11 is connected to the molten salt inlet of high-temperature molten salt furnace 6 and the molten salt inlet of molten salt heat exchanger 15. A portion of the high-temperature molten salt in high-temperature molten salt tank 11 is transported to molten salt heat exchanger 15 to exchange heat with feed water. The water is heated into high-temperature, high-pressure steam and then stored. Another portion of the high-temperature molten salt in high-temperature molten salt tank 11 is mixed with the low-temperature molten salt transported from low-temperature molten salt furnace 4 and transported together to high-temperature molten salt furnace 6. The molten salt outlet of the salt heat exchanger 15 is connected to the molten salt inlet of the low-temperature molten salt tank 1 to transport the heat-exchanged low-temperature molten salt to the low-temperature molten salt tank 1 for storage. The molten salt outlet of the low-temperature molten salt tank 1 is connected to the molten salt inlet of the low-temperature molten salt furnace 4, where the low-temperature molten salt is heated by the high-temperature flue gas transported from the high-temperature molten salt furnace 6. The molten salt outlet of the low-temperature molten salt furnace 4 is connected to both the molten salt inlet of the low-temperature molten salt tank 1 and the molten salt inlet of the high-temperature molten salt furnace 6. A portion of the low-temperature molten salt in the low-temperature molten salt furnace 4 is transported to the low-temperature molten salt tank 1 for storage, while the other portion is mixed with the high-temperature molten salt in the high-temperature molten salt tank 11 and transported together to the high-temperature molten salt furnace 6. In this embodiment, a molten salt heat storage system is added to the existing equipment of the steel plant. The released gas is sent to the burner 9 to burn and heat the molten salt, thereby storing the heat in the molten salt. This improves the flexibility of converter gas usage. The stored heat is then released by heat exchange between the high-temperature molten salt and water, generating high-temperature and high-pressure steam. This not only significantly improves the utilization rate of converter gas and reduces emissions, but also yields high-temperature, high-pressure, high-quality steam products, thereby increasing economic benefits.

[0023] Specifically, the gas inlet of the gas heater 8 is connected to a converter vented gas storage device 7 to store the converter head and tail gas of the steel plant and the vented gas caused by factors such as full tank or abnormal operation.

[0024] The flue gas outlet of the gas heater 8 is sequentially connected to a flue gas regulating valve 18, an induced draft fan 19, and a chimney. The gas heater 8 can utilize the waste heat from the flue gas of the low-temperature molten salt furnace 4 to heat the converter gas to 150℃~250℃. The flue gas regulating valve 18 is used to adjust the suction force within the flue and rationally control the flue gas flow rate according to the operating conditions. The induced draft fan 19 can increase the flue gas pressure by relying on externally input mechanical energy, creating a negative pressure environment to draw the flue gas out.

[0025] The converter vent gas recovery and utilization system provided in this embodiment also includes an air preheater 17. The air inlet of the air preheater 17 is connected to the outside, the air outlet of the air preheater 17 is connected to the air inlet of the burner 9, the flue gas inlet of the air preheater 17 is connected to the flue gas outlet of the low-temperature molten salt furnace 4, and the flue gas outlet of the air preheater 17 is connected to the flue gas inlet of the gas heater 8. The air preheater 17 uses the waste heat of the flue gas from the low-temperature molten salt furnace 4 to heat the air to between 200°C and 300°C.

[0026] The lower end of the high-temperature molten salt tank 11 is equipped with a high-temperature electric heater 12, which is used to heat, maintain, and heat the flowing liquid and gaseous media. The heating range is 400℃~600℃. The lower end of the low-temperature molten salt tank 1 is equipped with a low-temperature electric heater 2, which is used to heat, maintain, and heat the flowing liquid and gaseous media. The heating range of the low-temperature electric heater 2 is 250℃~350℃.

[0027] A high-temperature molten salt pump 13 is provided between the molten salt outlet of the high-temperature molten salt tank 11 and the molten salt inlet of the high-temperature molten salt furnace 6. A molten salt circulation pump 14 is provided between the molten salt outlet of the high-temperature molten salt tank 11 and the molten salt inlet of the molten salt heat exchanger 15. A high-temperature molten salt regulating valve 10 is provided between the molten salt outlet of the high-temperature molten salt furnace 6 and the molten salt inlet of the high-temperature molten salt tank 11. The high-temperature molten salt regulating valve 10 has the characteristic of being able to precisely regulate the flow rate of high-temperature molten salt.

[0028] A low-temperature molten salt pump 3 is provided between the molten salt outlet of the low-temperature molten salt tank 1 and the molten salt inlet of the low-temperature molten salt furnace 4. A low-temperature molten salt regulating valve 5 is provided between the molten salt outlet of the low-temperature molten salt furnace 4 and the molten salt inlet of the high-temperature molten salt furnace 6. The low-temperature molten salt regulating valve 5 has the characteristic of being able to precisely regulate the flow rate of low-temperature molten salt.

[0029] The molten salt heat exchanger 15 is equipped with a water inlet that connects to the outside. The molten salt heat exchanger 15 allows molten salt and water to exchange heat energy to generate superheated steam with a temperature range of 540℃ to 600℃, and the steam outlet of the molten salt heat exchanger 15 is connected to the steam inlet of the steam drum 16. The steam drum 16 is used for steam-water separation and steam purification, forming a water circulation loop and storing boiler water.

[0030] Both the high-temperature molten salt tank 11 and the low-temperature molten salt tank 1 have insulation layers on their side walls and are capable of bearing weight.

[0031] The molten salt is a binary mixed molten salt composed of potassium nitrate and sodium nitrate.

[0032] The converter vent gas consists of converter head and tail gas, as well as gas released due to factors such as full tank or operational interruption. The calorific value of the converter head and tail gas is 800~1500 kcal / m³, while the calorific value of other vent gas is 1800~2200 kcal / m³.

[0033] As a specific embodiment, the working process of this embodiment is as follows:

[0034] A. Heat storage stage

[0035] The converter gas released from the steel plant first enters the converter vent gas storage device 7 for storage. When needed, it is heated to 200°C by the gas heater 8 and then enters the burner 9. Air, preheated to 200°C by the air preheater 17, also enters the burner 9. The converter vent gas mixed with air in the burner 9 burns to a temperature of 1200°C, heating the molten salt in the high-temperature molten salt furnace 6 (the molten salt is a binary molten salt composed of potassium nitrate and sodium nitrate, with potassium nitrate and sodium nitrate accounting for 60% and 40% respectively). The molten salt is heated to 550°C and then transferred to the high-temperature molten salt tank 11 for storage. The flue gas produced after the mixed gas in the burner 9 burns enters the low-temperature molten salt furnace 4 and exchanges heat with the low-temperature molten salt. The low-temperature molten salt is heated to 250°C and then transferred to the low-temperature molten salt tank 1 for storage. After exchanging heat with low-temperature molten salt, the flue gas is transported to the air preheater 17 and the air therein is preheated to 200°C. Then it enters the gas heater 8 and the converter vent gas therein is heated to 150°C~250°C. After that, the flue gas passes through the flue regulating valve 18 and the induced draft fan 19, and finally is discharged from the chimney.

[0036] B. Heat release phase

[0037] When steam is required, the high-temperature molten salt at 550°C in the high-temperature molten salt tank 11 is pumped to the molten salt heat exchanger 15 using the high-temperature molten salt pump 13. In the heat exchanger, the high-temperature molten salt exchanges heat with water to generate high-temperature, high-pressure steam at 530°C, and the steam is then fed into the steam drum 16. After the high-temperature molten salt cools down to 250°C through heat exchange with water, it is then stored in the low-temperature molten salt tank 1.

[0038] This specification uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A converter vent gas recovery and utilization system, characterized in that: The system includes a high-temperature molten salt furnace, a high-temperature molten salt ladle, a low-temperature molten salt furnace, a low-temperature molten salt ladle, a gas heater, a burner, and a molten salt heat exchanger. The flue gas inlet of the gas heater is connected to the flue gas outlet of the low-temperature molten salt furnace. The gas inlet of the gas heater is used for the intake of gas to be treated. The gas outlet of the gas heater is connected to the gas inlet of the burner. The burner is used to heat the contents of the high-temperature molten salt furnace and generate flue gas. The air inlet of the burner is connected to the outside environment. The flue gas outlet of the high-temperature molten salt furnace is connected to the low-temperature molten salt ladle. The flue gas inlet of the salt furnace is connected, the molten salt outlet of the high-temperature molten salt furnace is connected to the molten salt inlet of the high-temperature molten salt tank, the molten salt outlet of the high-temperature molten salt tank is connected to the molten salt inlet of the high-temperature molten salt furnace and the molten salt inlet of the molten salt heat exchanger, the molten salt outlet of the molten salt heat exchanger is connected to the molten salt inlet of the low-temperature molten salt tank, the molten salt outlet of the low-temperature molten salt tank is connected to the molten salt inlet of the low-temperature molten salt furnace, and the molten salt outlet of the low-temperature molten salt furnace is connected to the molten salt inlet of the low-temperature molten salt tank and the molten salt inlet of the high-temperature molten salt furnace.

2. The converter vent gas recovery and utilization system according to claim 1, characterized in that: The gas inlet of the gas heater is connected to a converter vent gas storage device.

3. The converter vent gas recovery and utilization system according to claim 1, characterized in that: The flue gas outlet of the gas heater is sequentially connected to a flue gas regulating valve, an induced draft fan, and a chimney.

4. The converter vent gas recovery and utilization system according to claim 1, characterized in that: It also includes an air preheater, the air inlet of which is connected to the outside, the air outlet of which is connected to the air inlet of the burner, the flue gas inlet of which is connected to the flue gas outlet of the low-temperature molten salt furnace, and the flue gas outlet of which is connected to the flue gas inlet of the gas heater.

5. The converter vent gas recovery and utilization system according to claim 1, characterized in that: The lower end of the high-temperature molten salt tank is equipped with a high-temperature electric heater, the heating temperature range of which is 400℃~600℃; the lower end of the low-temperature molten salt tank is equipped with a low-temperature electric heater, the heating temperature range of which is 250℃~350℃.

6. The converter vent gas recovery and utilization system according to claim 1, characterized in that: A high-temperature molten salt pump is provided between the molten salt outlet of the high-temperature molten salt tank and the molten salt inlet of the high-temperature molten salt furnace; a molten salt circulation pump is provided between the molten salt outlet of the high-temperature molten salt tank and the molten salt inlet of the molten salt heat exchanger; and a high-temperature molten salt regulating valve is provided between the molten salt outlet of the high-temperature molten salt furnace and the molten salt inlet of the high-temperature molten salt tank.

7. The converter vent gas recovery and utilization system according to claim 1, characterized in that: A low-temperature molten salt pump is provided between the molten salt outlet of the low-temperature molten salt tank and the molten salt inlet of the low-temperature molten salt furnace, and a low-temperature molten salt regulating valve is provided between the molten salt outlet of the low-temperature molten salt furnace and the molten salt inlet of the high-temperature molten salt furnace.

8. The converter vent gas recovery and utilization system according to claim 1, characterized in that: The molten salt heat exchanger is provided with a water inlet that communicates with the outside, and the steam outlet of the molten salt heat exchanger is connected to the steam inlet of the steam drum.

9. The converter vent gas recovery and utilization system according to claim 1, characterized in that: Both the high-temperature molten salt tank and the low-temperature molten salt tank have insulation layers on their side walls.

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