System and method for coupling fine desulfurization and waste heat energy-saving utilization of blast furnace gas

Abstract

The invention discloses a blast furnace gas fine desulfurization coupling waste heat energy-saving utilization system and method, and the system comprises a bag-type dust collector, a residual pressure turbine, a heating device, a rotary heat exchanger, a steam heater and a dechlorination and hydrolysis integrated tower which are sequentially connected end to end; the dechlorination and hydrolysis integrated tower is communicated with the rotary heat exchanger, and after heat exchange, blast furnace gas subjected to dechlorination and hydrolysis treatment is cooled and desulfurized and then enters a gas main pipe network; a heat source of the heating device is a blast furnace hot blast stove, a hot air outlet of the blast furnace hot blast stove is connected with a hot air flue gas heat exchanger, and the hot air flue gas heat exchanger is connected with the heating device; and a heat source of the steam heater is flue gas in the large sintering flue. A cold source of the blast furnace gas cooler is from the refrigerator, a driving heat source of the refrigerator is from blast furnace slag flushing water, and the refrigerator is connected with the blast furnace gas cooler through cold water circulation. By adopting the system and the process provided by the invention, the energy head realizes fine desulfurization of blast furnace gas, and energy-saving comprehensive utilization of waste heat in the field of iron and steel industry can also be realized.

Description

Technical Field

[0001] The invention belongs to the technical field of energy conservation and environmental protection, and specifically relates to a system and method for energy-saving utilization of blast furnace gas fine desulfurization coupled with waste heat. Background Art

[0002] The statements herein merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Blast furnace gas (BFG) is a combustible byproduct produced during the blast furnace ironmaking process. Its primary components are CO2, CO, H2, N2, hydrocarbons, and a certain amount of sulfides. Although BFG has a relatively low calorific value, its high production volume makes it a key internal fuel for steel companies. It is typically used for internal heating, power generation with gas and steam turbines, and external supply.

[0004] The sulfides contained in blast furnace gas are primarily hydrogen sulfide and a small amount of organic sulfur, including carbonyl sulfide. Hydrogen sulfide itself is highly corrosive, especially in the presence of water vapor, causing severe corrosion to gas pipelines, valves, turbines, gasholders, and other equipment. After combustion, the sulfides in blast furnace gas are converted into sulfur dioxide, which condenses in low-temperature regions and causes dew point corrosion, severely shortening the service life of pipelines, waste heat recovery devices, gas boiler tail flues, chimneys, and downstream equipment. Furthermore, sulfur dioxide is a major atmospheric pollutant that contributes to acid rain, harming the ecological environment and human health. Therefore, desulfurization of blast furnace gas is essential.

[0005] There are many downstream gas consumption points for blast furnace gas and they are relatively scattered. The steel industry has entered the era of "ultra-low emissions". Conventional terminal flue gas treatment methods have problems such as many treatment points, high investment, large land area, many operating failure points, and high operating costs, which have caused a significant increase in the environmental protection costs of enterprises.

[0006] In addition, there is a lot of waste heat in the steel smelting process, and the recovery potential is large. If it cannot be effectively recovered, it will cause energy waste. Summary of the Invention

[0007] In view of the deficiencies in the prior art, the present invention aims to provide a system and method for blast furnace gas fine desulfurization coupled with waste heat energy-saving utilization.

[0008] In order to achieve the above object, the present invention is implemented through the following technical solutions: In a first aspect, the present invention provides a system for blast furnace gas fine desulfurization coupled with waste heat energy-saving utilization, comprising a bag filter, a waste pressure turbine, a temperature riser, a rotary heat exchanger, a steam heater, a chlorine removal and hydrolysis integrated tower, a cooler, and a desulfurization tower connected end to end in sequence; The chlorine removal and hydrolysis integrated tower is connected to the rotary heat exchanger and is used to exchange heat between the blast furnace gas after the chlorine removal and hydrolysis treatment and the untreated blast furnace gas. After the heat exchange, the blast furnace gas after the chlorine removal and hydrolysis treatment is cooled and desulfurized before entering the gas main network; The heat source of the warmer is a blast furnace hot blast furnace, the hot blast outlet of the blast furnace hot blast furnace is connected to the hot blast flue gas heat exchanger, water is used as a circulating heat exchange medium to heat the circulating heat exchange medium, and the hot blast flue gas heat exchanger is connected to the blast furnace gas warmer through circulating water; The heat source of the steam heater is the flue gas in the sintering flue. The flue gas in the sintering flue heats the desalted water in the flue heat exchanger into steam, which provides heat for the steam heater.

[0009] The cold source of the blast furnace gas cooler comes from a refrigerator, the driving heat source of the refrigerator comes from blast furnace slag flushing water, and the refrigerator and the blast furnace gas cooler are connected through a cold water circulation.

[0010] In a second aspect, the present invention provides a method for coupling blast furnace gas fine desulfurization with waste heat energy-saving utilization, comprising the following steps: After the blast furnace gas is bag-dusted, it enters the residual pressure turbine to generate electricity, and the temperature drops to 40-50℃; The blast furnace gas after power generation exchanges heat with the hot air from the blast furnace using circulating water as the heat transfer medium, and the blast furnace gas is heated to 60-70°C. It then enters the rotary heat exchanger and exchanges heat with the blast furnace gas after dechlorination and hydrolysis, raising its temperature to 100-110°C. It then enters the steam heater and is heated to 115-130°C, where the heated blast furnace gas undergoes dechlorination and hydrolysis. The blast furnace gas after dechlorination and hydrolysis treatment is heat exchanged with untreated blast furnace gas, and then further cooled to 45-60℃ through a gas cooler, and then desulfurized; The desulfurized blast furnace gas enters the gas main network.

[0011] The beneficial effects achieved by one or more embodiments of the present invention are as follows: The installation of a blast furnace gas warmer in front of the blast furnace gas rotary heat exchanger significantly reduces acid corrosion of the heat exchanger's components, extending the exchanger's service life and heat exchange efficiency. Furthermore, the warmer utilizes waste heat from the hot blast furnace's flue gas, achieving heat recovery while reducing the operating energy consumption of the blast furnace gas.

[0012] A blast furnace gas steam heater is installed at the original flue gas outlet of the blast furnace gas rotary heat exchanger. The steam heater utilizes the waste heat of the flue gas from the sintering flue. The quality of the steam generated can effectively increase the temperature of the blast furnace gas, realize the effective utilization of the waste heat of the flue gas, ensure the optimal active temperature and hydrolysis efficiency of the blast furnace gas dechlorination hydrolysis, and greatly reduce the operating energy consumption of the blast furnace gas.

[0013] Utilizing the waste heat from blast furnace slag flushing water to drive the chiller significantly improves cooling efficiency and stability, while reducing operating energy consumption. The blast furnace gas cooler has a smaller heat exchange area when operating with cooling water at 7°C, reducing both operating resistance and energy consumption. Furthermore, the gas temperature before entering the blast furnace gas desulfurization tower is effectively controlled below 50°C, preventing temperature fluctuations from impacting desulfurization efficiency or shortening the life of the desulfurizer.

[0014] Waste heat within the steel mill provides a high-quality heat source for the blast furnace gas heater, blast furnace gas steam heater, and blast furnace gas cooler. This not only minimizes the heat exchange area and operating resistance of the heat exchangers, but also provides a stable, highly active temperature window for the dechlorination hydrolyzer and desulfurizer. For the same blast furnace gas volume, the blast furnace gas system achieves the lowest energy consumption and cost, minimizes the resistance of the blast furnace gas pipeline network, and minimizes the impact on the power generation efficiency of the residual pressure turbine.

[0015] The system and process of the present invention can realize the fine desulfurization of blast furnace gas from the energy source, and realize the comprehensive energy-saving utilization of waste heat in the steel industry, effectively combining energy conservation and environmental protection. The energy inside can be efficiently utilized and recycled through technical means, thereby improving energy utilization efficiency, reducing energy waste, and greatly reducing the construction and operation costs of flue gas pollutants. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0017] Figure 1 It is a schematic diagram of the overall structure of an embodiment of the present invention.

[0018] Among them, 1-bag dust collector; 2-exhaust pressure turbine; 3-heater; 4-rotary heat exchanger; 5-steam heater; 6-chlorine removal and hydrolysis integrated tower; 7-blast furnace hot blast furnace; 8-hot air flue gas heat exchanger; 9-high temperature circulating water pump; 10-drain valve; 11-gas main network; 12-desulfurization tower; 13-cooler; 14-cooling circulating water pump; 15-refrigeration machine; 16-slag flushing water circulating water pump; 17-blast furnace slag flushing water; 18-sintering flue; 19-flue heat exchanger. DETAILED DESCRIPTION

[0019] It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0020] In a first aspect, the present invention provides a system for blast furnace gas fine desulfurization coupled with waste heat energy-saving utilization, comprising a bag filter, a waste pressure turbine, a temperature riser, a rotary heat exchanger, a steam heater, and a chlorine removal and hydrolysis integrated tower connected end to end; The chlorine removal and hydrolysis integrated tower is connected to the rotary heat exchanger and is used to exchange heat between the blast furnace gas after the chlorine removal and hydrolysis treatment and the untreated blast furnace gas. After the heat exchange, the blast furnace gas after the chlorine removal and hydrolysis treatment is cooled and desulfurized before entering the gas main network; The heat source of the temperature riser is a blast furnace hot blast furnace, the hot blast outlet of the blast furnace hot blast furnace is connected to the hot blast flue gas heat exchanger, water is used as a circulating heat exchange medium, the hot blast from the blast furnace hot blast furnace is used to heat the circulating heat exchange medium, and the hot blast flue gas heat exchanger is connected to the temperature riser; The heat source of the steam heater is the flue gas in the sintering flue. The flue gas in the sintering flue heats the desalted water in the flue heat exchanger, and the desalted water is heated into steam to provide heat for the steam heater.

[0021] In some embodiments, the hot air and flue gas heat exchanger cools the hot air after heat exchange and discharges it to the chimney through the hot air outlet.

[0022] In some embodiments, the steam outlet of the steam heater is connected to the condensate tank via a pipe, and a steam trap is provided on the pipe. The steam trap, also known as a steam trap, is installed at the end of the steam heating pipeline to continuously drain condensate from the steam heating pipeline to the outside of the pipeline.

[0023] In some embodiments, the large flue heat exchanger is a shell and tube heat exchanger, desalted water is passed into the heat exchange tubes, the shells of the heat exchange tubes are connected to the sintering large flue for passing flue gas, and the flue gas outlet is connected to the sintering flue gas environmental protection treatment system through a pipeline.

[0024] In some embodiments, a cooler is used to cool the blast furnace gas after the dechlorination and hydrolysis treatment, and the cold source of the cooler comes from a refrigerator.

[0025] In a second aspect, the present invention provides a method for coupling blast furnace gas fine desulfurization with waste heat energy-saving utilization, comprising the following steps: After the blast furnace gas is bag-dusted, it enters the residual pressure turbine to generate electricity, and the temperature drops to 40-50℃; The blast furnace gas after power generation exchanges heat with the hot air from the blast furnace hot blast stove through the circulating water medium, raising the temperature to 60-70°C; then enters the rotary heat exchanger, exchanges heat with the blast furnace gas after dechlorination and hydrolysis, raising the temperature to 100-110°C; then enters the steam heater, and the blast furnace gas after further heating undergoes dechlorination and hydrolysis treatment; The blast furnace gas after dechlorination and hydrolysis treatment is heat exchanged with untreated blast furnace gas, and then further cooled to 45-60℃ through a gas cooler, and then desulfurized; The desulfurized blast furnace gas enters the gas main network.

[0026] The heater is a static device that uses a non-metallic heat exchanger with strong corrosion resistance; while the heat exchange element of the rotary heat exchanger is made of metal and has weak corrosion resistance.

[0027] In some embodiments, the chlorine removal hydrolysis process is to hydrolyze carbonyl sulfide in blast furnace gas into hydrogen sulfide.

[0028] The reaction principle is: carbonyl sulfide is catalytically hydrolyzed to produce hydrogen sulfide. The catalyst is a γ-Al2O3-based carrier loaded with active components (TiO2, K2O, Fe2O3) to enhance resistance to sulfation.

[0029] In some embodiments, the temperature of the blast furnace gas after being heated by the steam heater is 115-130°C.

[0030] Preferably, the heat source of the steam heater is the flue gas in the sintering flue.

[0031] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0032] like Figure 1 As shown, a system for blast furnace gas fine desulfurization coupled with waste heat energy-saving utilization includes a bag filter 1, a waste pressure turbine 2, a temperature riser 3, a rotary heat exchanger 4, a steam heater 5, and a chlorine removal and hydrolysis integrated tower 6 connected end to end in sequence; The chlorine removal and hydrolysis integrated tower 6 is connected to the rotary heat exchanger 4 and is used to exchange heat between the blast furnace gas after the chlorine removal and hydrolysis treatment and the untreated blast furnace gas. After the heat exchange, the blast furnace gas after the chlorine removal and hydrolysis treatment is cooled and desulfurized and enters the gas main network 11; The heat source of the temperature riser 3 is the blast furnace hot blast stove 7, the hot blast outlet of the blast furnace hot blast stove 7 is connected to the hot blast flue gas heat exchanger 8 for heating the circulating heat exchange medium therein, and the hot blast flue gas heat exchanger 8 is connected to the temperature riser 3; The heat source of the steam heater 5 is the flue gas in the sintering flue 18. The flue gas in the sintering flue 18 heats the circulating heat exchange medium in the flue heat exchanger 19 to provide heat for the steam heater.

[0033] The hot air cooled by the hot air-smoke heat exchanger 8 is discharged to the chimney through the hot air outlet.

[0034] The steam outlet of the steam heater 5 is connected to the condensate tank via a pipe, on which a steam trap 10 is provided. The steam trap 10, also known as a steam trap, is installed at the end of the steam-heated pipeline to continuously discharge condensate from the steam-heated pipeline to the outside of the pipeline.

[0035] The large flue heat exchanger 19 is a shell and tube heat exchanger. Water is passed into the heat exchange tubes. The heat exchange tubes and the shell are connected to the sintered large flue 18 for passing flue gas. A flue gas outlet is provided on the shell, and the flue gas outlet is connected to the flue gas treatment system through a pipeline.

[0036] The cooler 13 is used to cool the blast furnace gas after the dechlorination and hydrolysis treatment, and the cold source of the cooler 13 comes from a refrigerator.

[0037] The blast furnace gas enters the blast furnace gas bag filter 1 for bag dust removal, reducing the dust in the blast furnace gas to 10mg / Nm 3 About; after the blast furnace gas after bag dust removal enters the residual pressure turbine 2 to generate electricity, the pressure of the blast furnace gas drops to 15~20Kpa and the temperature drops to 40~50℃.

[0038] Since the active temperature of the blast furnace gas desulfurization and dechlorination hydrolysis agent is between 110 and 150°C, when the blast furnace gas enters the blast furnace gas dechlorination and hydrolysis integrated tower 6, it needs to pass through the blast furnace gas heater 3 and the blast furnace gas rotary heat exchanger 4 to be heated to the optimal efficiency temperature for reaction to ensure hydrolysis efficiency and service life.

[0039] Cl in blast furnace gas - Acidic gases can irreversibly poison the organic sulfur conversion catalyst (the carrier of the organic sulfur conversion catalyst is alkaline). Furthermore, acidic gases compete with COS, severely impacting hydrolysis efficiency. In the system design of this invention, a pretreatment system is installed at the front end of the catalytic hydrolysis system, which is filled with a dechlorinating agent to remove acidic gases and adsorb impurities.

[0040] Organic sulfur conversion principle: COS+H2O→H2S+CO2; CS2+2H2O→2H2S+CO2.

[0041] Principle of iron oxide dry desulfurization: Fe2O3.H2O+3H2S→ Fe2S3.H2O +3H2O (under alkaline environment); Fe2O3.H2O + 3H2S → 2FeS + 1 / 8S8+ 4H2O (in acidic environment).

[0042] The acidic gases in the blast furnace gas after the residual pressure turbine 2 dissolve in the condensate, and factors such as the precipitation of chloride ions in the gas at high temperatures can cause corrosion of the heat exchange components of the rotary heat exchanger 4. Therefore, a temperature booster 3 is used to raise the blast furnace gas to 65°C before it enters the rotary heat exchanger 4. The higher the blast furnace gas temperature is above the acid dew point, the lower the risk of corrosion on the heat exchange components of the rotary heat exchanger 4, thereby improving the heat exchange efficiency and extending the service life of the rotary heat exchanger 4.

[0043] The outlet temperature of the raw flue gas side of the rotary heat exchanger 4 is 105°C. The temperature of the blast furnace gas is raised to 120°C by the steam heater 5. The blast furnace gas then enters the blast furnace gas dechlorination and hydrolysis integrated tower 6. The carbonyl sulfide in the blast furnace gas is hydrolyzed into hydrogen sulfide. The initial hydrolysis efficiency is above 95%. The hydrolyzed blast furnace gas enters the clean flue gas inlet side of the rotary heat exchanger 4. Considering that the temperature drop of the blast furnace gas dechlorination and hydrolysis integrated tower 6 is 2-3°C, the temperature of the clean flue gas inlet side of the rotary heat exchanger 4 is 117-118°C, and the temperature of the clean flue gas outlet side of the rotary heat exchanger 4 is about 80°C.

[0044] Since the desulfurization agent activity temperature of blast furnace gas is 45-60°C, the blast furnace gas enters the cooler 13 to be cooled to about 50°C, and then enters the desulfurization tower 12 for desulfurization. The desulfurized blast furnace gas enters the gas main network 11.

[0045] The heat source for the warmer 3 comes from the blast furnace hot blast furnace 7. A hot air flue gas heat exchanger 8 is installed in the flue of the blast furnace hot blast furnace 7. A circulating water pipeline transfers heat between the hot air flue gas heat exchanger 8 and the warmer 3. The high-temperature water that absorbs heat in the hot air flue gas heat exchanger 8 enters the warmer 3. The high-temperature water transfers heat through the warmer 3 to raise the temperature of the blast furnace gas to 65°C. The cooled circulating water then flows through the high-temperature circulating water pump 9 into the hot air flue gas heat exchanger 8 to absorb the waste heat of the blast furnace hot blast flue gas. The cooled blast furnace hot blast flue gas is then discharged into the chimney. This circulation not only realizes the comprehensive utilization of the waste heat of the blast furnace hot blast furnace, but also reduces the operating energy consumption cost of the blast furnace gas fine desulfurization.

[0046] The steam source for the steam heater 5 comes from the sintering flue 18, where a flue heat exchanger 19 is installed. Demineralized water from the waste heat boiler enters this heat exchanger, generating steam at approximately 150°C. This steam then enters the blast furnace gas steam heater 5, raising the raw flue gas outlet temperature of the rotary heat exchanger 4 from 105°C to 120°C. After heat exchange, the steam transforms into condensate, which is discharged into the condensate tank through a steam trap 10. This achieves comprehensive utilization of sintering waste heat and reduces the energy consumption of blast furnace gas fine desulfurization.

[0047] Cooler 13's cold source comes from chiller 15, which is driven by waste heat from blast furnace slag flushing water, typically at a temperature of 70-90°C. The chiller's cooling water outlet temperature is typically around 7°C. This cooling water enters cooler 13 via cooling circulating water pump 14, cooling the blast furnace gas from 80°C to around 50°C before entering the blast furnace gas desulfurization tower for desulfurization, maintaining high desulfurizer activity and efficiency.

[0048] The circulating slag water from the blast furnace slag water 17 to the refrigerator 15 is heat-transferred through the slag water circulating water pump 16. The waste heat of the blast furnace slag water is comprehensively utilized, and the cooled blast furnace slag water saves the operating energy consumption of the quenching tower, while reducing the operating cost of the blast furnace gas fine desulfurization.

[0049] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A system for blast furnace gas fine desulfurization coupled with waste heat energy-saving utilization, characterized by: It includes a bag dust collector, a residual pressure turbine, a temperature riser, a rotary heat exchanger, a steam heater and a chlorine removal and hydrolysis integrated tower connected end to end; The chlorine removal and hydrolysis integrated tower is connected to the rotary heat exchanger and is used to exchange heat between the blast furnace gas after the chlorine removal and hydrolysis treatment and the untreated blast furnace gas. After the heat exchange, the blast furnace gas after the chlorine removal and hydrolysis treatment is cooled and desulfurized before entering the gas main network; The heat source of the temperature riser is a blast furnace hot blast furnace, the hot blast outlet of the blast furnace hot blast furnace is connected to the hot blast flue gas heat exchanger, the circulating water is used as the circulating heat exchange medium to heat the circulating heat exchange medium, and the hot blast flue gas heat exchanger is connected to the temperature riser; The heat source of the steam heater is the flue gas in the sintering flue. The flue gas in the sintering flue heats the desalted water in the flue heat exchanger into steam, which provides heat for the steam heater.

2. The system for blast furnace gas fine desulfurization coupled with waste heat energy-saving utilization according to claim 1 is characterized in that: The hot air smoke heat exchanger is provided with a hot air outlet.

3. The system for blast furnace gas fine desulfurization coupled with waste heat energy-saving utilization according to claim 1 is characterized in that: The steam outlet of the steam heater is connected to the condensate tank through a pipeline, and a steam trap is provided on the pipeline.

4. The system for blast furnace gas fine desulfurization coupled with waste heat energy-saving utilization according to claim 1 is characterized in that: The large flue heat exchanger is a shell and tube heat exchanger. Water is passed into the heat exchange tube. The heat exchange tube and the shell are connected to the sintered large flue for passing flue gas. A flue gas outlet is provided on the shell, and the flue gas outlet is connected to the flue gas treatment system through a pipeline.

5. The system for blast furnace gas fine desulfurization coupled with waste heat energy-saving utilization according to claim 1 is characterized in that: A cooler is used to cool the blast furnace gas after dechlorination and hydrolysis treatment, and the cold source of the cooler comes from a refrigerator.

6. A method for energy-saving utilization of blast furnace gas fine desulfurization coupled with waste heat, characterized by: The method is carried out by using the system for blast furnace gas fine desulfurization coupled with waste heat energy-saving utilization as described in any one of claims 1 to 5, specifically comprising the following steps: After the blast furnace gas is bag-dusted, it enters the residual pressure turbine to generate electricity, and the temperature drops to 40-50℃; The blast furnace gas after power generation exchanges heat with the hot air from the blast furnace hot blast stove, raising its temperature to 60-70°C; then enters the rotary heat exchanger, exchanges heat with the blast furnace gas after dechlorination and hydrolysis, raising its temperature to 100-110°C; then enters the steam heater, raising its temperature to 115-130°C, and the heated blast furnace gas undergoes dechlorination and hydrolysis treatment; The blast furnace gas after the chlorine removal and hydrolysis treatment is heat exchanged with the untreated blast furnace gas, and then further cooled and desulfurized; The desulfurized blast furnace gas enters the gas main network.

7. The method for blast furnace gas fine desulfurization coupled with waste heat energy-saving utilization according to claim 6, characterized in that: The dechlorination hydrolysis treatment is to hydrolyze carbonyl sulfide in blast furnace gas into hydrogen sulfide.

8. The method for blast furnace gas fine desulfurization coupled with waste heat energy-saving utilization according to claim 6, characterized in that: The temperature of blast furnace gas after being heated by steam heater is 115-130℃.

9. The method for blast furnace gas fine desulfurization coupled with waste heat energy-saving utilization according to claim 6, characterized in that: The heat source of the steam heater is the flue gas in the sintering flue.

10. The method for blast furnace gas fine desulfurization coupled with waste heat energy-saving utilization according to claim 6, characterized in that: The temperature after further cooling is 45-60°C.

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