Device for reducing sulfur dioxide emission of steel rolling heating furnace

Abstract

The utility model relates to a device for reducing sulfur dioxide emission of a steel rolling heating furnace. A device for reducing sulfur dioxide emission of a steel rolling heating furnace comprises a pretreatment tower (1), the system is characterized by further comprising a temperature swing adsorption purification tower (2), a first pressurizing machine (3), a first preheater (4), a first-section hydrolysis tower (5), a second preheater (6), a second-section hydrolysis tower (7), a cooler (8), a fine desulfurization tower (9), a first coal gas mixing device (10), a second pressurizing machine (11), a second coal gas mixing device (12) and a condensate water recovery device (13). The desulfurization device is high in desulfurization efficiency.

Description

Technical Field

[0001] The utility model relates to the field of a multi-step method for purifying waste gas, in particular to a device for reducing sulfur dioxide emission from a steel rolling heating furnace. Background Art

[0002] At present, the steel mill rolling process generally uses a mixture of coke oven gas, blast furnace gas and converter gas produced as by-products of the main steel production processes such as coking, ironmaking and steelmaking as fuel for the heat treatment furnace. This can make full use of the thermal energy of the gas, reduce gas emissions, and reduce pollution to the environment. It is an effective means of energy conservation and emission reduction. However, the sulfur components such as hydrogen sulfide (H2S) and carbonyl sulfide (COS), CS2, and thiophene (C4H4S) contained in the gas are burned as SO2 in the flue gas and emitted into the atmosphere to form pollution. Flue gas that has not been purified cannot meet the SO2 concentration limit of ≤50mg / m3 for flue gas (baseline oxygen content of dry flue gas is 8%) emitted from the steel rolling heat treatment furnace in the "Opinions on Promoting the Implementation of Ultra-low Emissions in the Steel Industry". 3 requirements.

[0003] In this regard, the traditional environmental protection transformation technology route is post-combustion desulfurization, installing a desulfurization device in the flue gas discharge flue of the furnace, and using calcium method (limestone / gypsum as desulfurizer), magnesium method (magnesium oxide as desulfurizer), ammonia method (synthetic ammonia as desulfurizer), sodium method (sodium hydroxide as desulfurizer) and other processes for desulfurization. However, the amount of flue gas doubles after combustion, and large steel companies often have dozens of steel rolling heat treatment furnaces with scattered locations. If a desulfurization device is installed in the flue of each heating furnace, there are problems such as a large amount of flue gas to be purified, a large number of flue gas desulfurization devices, high investment, difficult management, tight location in the general plan of the old factory, and difficulty in implementation due to limited sites.

[0004] In recent years, the steel enterprises have explored and applied the technology route of desulfurization of coke oven gas or blast furnace gas before combustion. At the source of coke oven gas generation - the outlet of the gas refining system of the coking unit (before entering the coke oven gas pipeline network of the whole plant), a fine desulfurization device is installed (mostly only hydrogen sulfide in the coke oven gas is removed, no or a small amount of organic sulfur is removed); at the source of blast furnace gas generation - before and after the blast furnace TRT, an organic sulfur hydrolysis device and a hydrogen sulfide removal device are installed, so that the sulfur content of the coke oven gas and blast furnace gas sent out of the coking unit and blast furnace unit and entering the gas pipeline network of the whole plant has been reduced, so that the back-end process using these purified gases can achieve ultra-low emission standards. Taking a large steel joint venture with an annual steel output of 15 million tons / a as an example, the average calendar hour generation of its blast furnace gas is about 2.45 million standard m 3 / h, and the average calendar hourly generation of coke oven gas is about 280,000 to 320,000 standard cubic meters. 3 / h. If these coal gases are desulfurized at the source, the gas processing volume is 2.73 to 2.77 million standard m 3 / h, but there are also problems such as large amount of gas to be purified, high investment and operating costs, and desulfurization at the source of the blast furnace affecting the TRT power generation output.

[0005] In recent years, as my country's restrictions on air pollutant emissions have become increasingly stringent, many steel companies have successively built end-of-pipe flue gas desulfurization facilities such as blast furnace hot blast stove flue gas desulfurization, coke oven flue gas desulfurization, sintering flue gas desulfurization, and boiler flue gas desulfurization through environmental protection transformation. Ultra-low emission standards have been achieved in the main users of steel plant gas - ironmaking blast furnace hot blast stoves, sintering, coking coke oven chimneys, self-contained power plant boilers and other processes; cold rolling heating furnaces and annealing furnaces can also mostly meet the standards because the current ultra-low emission standards stipulate that the baseline oxygen content of dry flue gas is 15%; only the problem of non-compliance with emissions from steel rolling (hot rolling) heat treatment furnaces is more prominent because it is difficult to solve. The amount of blast furnace gas and coke oven gas used by these users only accounts for about 7% of the total amount. If the blast furnace gas and coke oven gas are finely desulfurized at the source of the gas, this will result in repeated installation and excessive treatment of desulfurization facilities, and the high cost and uneconomical cost of achieving environmental protection goals. Figure 1 shown.

[0006] According to data analysis, the sulfur in the mixed gas used in the hot rolling series of furnaces in steel plants comes from coke oven gas and blast furnace gas. Converter gas basically does not contain sulfur, and the sulfur contributed by coke oven gas accounts for more than 70% of the total sulfur, while the sulfur component brought by blast furnace gas accounts for less than 30% of the total sulfur. Only fine desulfurization of blast furnace gas cannot achieve ultra-low emission standards. It is necessary to supplement it with a large amount of sulfur-free gas such as converter gas and natural gas to reduce the proportion of coke oven gas in the mixed gas to meet the standards. This method has the disadvantages of unstable supply of converter gas itself, large fluctuations in calorific value, difficulty in control, and high cost of mixing with natural gas. Utility Model Content

[0007] In order to overcome the defects of the prior art and provide a rolling auxiliary equipment with high desulfurization efficiency and environmental protection, the utility model discloses a device for reducing sulfur dioxide emission from a steel rolling heating furnace.

[0008] The utility model achieves the invention purpose through the following technical solutions:

[0009] A device for reducing sulfur dioxide emissions from a steel rolling heating furnace includes a pretreatment tower, and is characterized in that it also includes a temperature swing adsorption purification tower, a first compressor, a first preheater, a first hydrolysis tower, a second preheater, a second hydrolysis tower, a cooler, a fine desulfurization tower, a first gas mixing device, a second compressor, a second gas mixing device, and a condensate recovery device.

[0010] The inlet of the pretreatment tower is connected to the main pipe of coke oven gas sent to the steel rolling heat treatment furnace, and the outlet of the pretreatment tower is connected to the temperature swing adsorption purification tower. The pretreatment tower is filled with desulfurizer;

[0011] The air inlet of the temperature swing adsorption purification tower is connected to the outlet of the pretreatment tower, and the air outlet of the temperature swing adsorption purification tower is connected to the inlet of the first compressor;

[0012] The air inlet of the first compressor is connected to the outlet of the temperature swing adsorption purification tower, and the air outlet of the first compressor is connected to the first preheater.

[0013] The air outlet of the first compressor is also connected to the air inlet of the regeneration gas heater, the air outlet of the regeneration gas heater is connected to the air inlet of the temperature swing adsorption purification tower, the steam inlet of the regeneration gas heater is connected to the steam source, the water outlet of the regeneration gas heater is connected to the condensate recovery device, and the air inlet and the air outlet of the regeneration gas heater are also connected through a regeneration gas bypass pipeline;

[0014] The cold gas inlet of the first preheater is connected to the outlet of the first compressor, the cold gas outlet of the first preheater is connected to the first hydrolysis tower, the hot gas inlet of the first preheater is connected to the outlet of the second hydrolysis tower, and the hot gas outlet of the first preheater is connected to the cooler;

[0015] The air inlet of the first hydrolysis tower is connected to the cold gas outlet of the first preheater, the air outlet of the first hydrolysis tower is connected to the gas inlet of the second preheater, and the catalyst is loaded in the first hydrolysis tower;

[0016] The gas inlet of the second preheater is connected to the outlet of the first-stage hydrolysis tower, and the gas outlet of the second preheater is connected to the gas inlet of the second-stage hydrolysis tower;

[0017] The air inlet of the second-stage hydrolysis tower is connected to the gas outlet of the second preheater, and the air outlet of the second-stage hydrolysis tower is connected to the gas inlet of the first preheater, and the catalyst is loaded in the second-stage hydrolysis tower;

[0018] The air inlet of the cooler is connected to the hot gas outlet of the first preheater, and the air outlet of the cooler is connected to the fine desulfurization tower.

[0019] The air inlet of the fine desulfurization tower is connected to the outlet of the cooler, and the air outlet of the fine desulfurization tower is connected to the first coal gas mixing device. The fine desulfurization tower is filled with a carbon-based desulfurizer or an iron oxide-based desulfurizer.

[0020] A bypass pipeline is set between the inlet of the pretreatment tower and the outlet of the fine desulfurization tower. A cut-off valve is provided on the bypass pipeline. The cut-off valve is closed during normal production. When other components fail, the cut-off valve is quickly opened, and the coal gas enters the first coal gas mixing device through the bypass pipeline.

[0021] The inlet of the first coal gas mixing device is connected to the outlet of the fine desulfurization tower, and the outlet of the first coal gas mixing device is connected to the second compressor.

[0022] The air inlet of the second compressor is connected to the outlet of the first gas mixing device, and the air outlet of the second compressor is connected to the second gas mixing device.

[0023] The gas inlet of the second gas mixing device is connected to the outlet of the second compressor, and the gas outlet of the second gas mixing device is connected to the main pipe for sending mixed gas to the steel rolling heating furnace.

[0024] The condensate recovery device is connected to the second preheater and the regeneration gas heater.

[0025] The device for reducing sulfur dioxide emissions from a steel rolling heating furnace is characterized in that: there are at least two pretreatment towers, and the pretreatment towers are filled with an iron oxide-based desulfurizer;

[0026] The first-stage hydrolysis tower and the second-stage hydrolysis tower are both filled with a metal-based catalyst comprising at least one metal element selected from the group consisting of aluminum, titanium and silicon.

[0027] When the utility model is used, the following steps are implemented in sequence:

[0028] Pretreatment: H2S in coke oven gas reacts with desulfurizer and oxygen in the pretreatment tower to generate elemental sulfur which is stored in the desulfurizer. The desulfurizer is replaced after being saturated with adsorption. After pretreatment in the pretreatment tower, the H2S content in coke oven gas is reduced to no more than 50mg / m 3 , enters the temperature swing adsorption pretreatment tower;

[0029] Temperature swing adsorption: The coal gas enters the temperature swing adsorption purification tower from the bottom of the tower. The adsorbent filled in the tower selectively adsorbs impurities such as H2S, tar, naphthalene and benzene in the coal gas at room temperature. When the impurities adsorbed by the adsorbent in the tower reach saturation, it enters the regeneration process;

[0030] Pressurization: After the removal of impurities such as tar, naphthalene and benzene, the coke oven gas is pressurized by the first compressor, so that the pressure of the coke oven gas can overcome the resistance drop of the subsequent process equipment and pipelines;

[0031] Regeneration: During regeneration, a stream of purified gas is taken from the first compressor and connected to the temperature swing adsorption purification tower. The purified gas is used as "regeneration gas" and is heated by the regeneration gas heater to desorb the impurities in the inner pores of the adsorbent. After regeneration is complete, the regeneration gas is used to cold-blow the adsorbent bed of the temperature swing adsorption purification tower through the regeneration gas bypass pipeline to reduce it to room temperature. In order to achieve the purpose of continuous production, the temperature swing adsorption purification tower is set by setting programmable valves to switch multiple towers to alternately adsorb and regenerate. After regeneration, the regeneration gas is sent to the end user such as the boiler equipped with flue gas desulfurization facilities. The heat source of the regeneration gas heater comes from the steam of the external pipeline network, and its condensed water is discharged into the condensed water recovery device;

[0032] Preheating: In the first preheater, the pressurized cold gas exchanges heat with the hot gas from the outlet of the second hydrolysis tower. The temperature of the cold gas rises from 45℃ to 60℃ to 80℃ to 120℃ before entering the first hydrolysis tower. At the same time, the temperature of the hot gas drops from 180℃ to about 110℃ before entering the cooler.

[0033] Hydrolysis: At a temperature of 80℃ to 120℃, the organic sulfur components including COS and CS2 in the coke oven gas in the first hydrolysis tower react with the water vapor contained in the gas under the action of the catalyst to generate H2S. More than 98% of the COS in the coke oven gas is converted into H2S, and then enters the second preheater to continue to heat up;

[0034] Preheating: In the second preheater, the coal gas after the first hydrolysis undergoes heat exchange with 260℃, 3.2MPa~3.6MPa steam. The temperature continues to rise from 80℃~120℃ to 110℃~180℃ before entering the second hydrolysis tower. The steam condensate is discharged into the condensate recovery device;

[0035] Hydrolysis: At a temperature of 110℃~180℃, CS2 in the coke oven gas in the second-stage hydrolysis tower undergoes a hydrolysis reaction with the water vapor contained in the gas under the action of a catalyst. About 80% of the CS2 in the coke oven gas is converted into H2S, which then enters the first preheater;

[0036] Cooling: After hydrolysis, the gas is cooled to room temperature in the cooler;

[0037] Fine desulfurization: In the fine desulfurization tower, H2S in the coal gas reacts with the desulfurizer and oxygen to generate elemental sulfur which is stored in the desulfurizer. The desulfurizer is replaced after it is saturated with adsorption.

[0038] Mixing: The coke oven gas that has undergone fine desulfurization and the blast furnace gas that has not undergone desulfurization from the pipeline network outside the plant are mixed in a certain proportion in the first gas mixing device. The mixing is controlled by a flow meter, a flow regulating valve and a calorific value meter.

[0039] Pressurization: The mixed gas of high-coke and coke is pressurized by the second compressor, so that the pressure of the mixed gas can meet the requirements of the rear-end steel rolling heating furnace;

[0040] Mixing: The purified high coke mixed gas is mixed with the converter gas in a certain proportion in the second gas mixing device to make full use of the converter gas. The mixing is controlled by a flow meter, a flow regulating valve and a calorific value meter to form a calorific value of 1800kcal / standard m 3 ~2400kcal / standard m 3 The mixed gas is sent to the users of steel rolling heat treatment furnace outside the boundary through pipelines;

[0041] Condensation: The condensate recovery device collects the steam condensate discharged from the second preheater and the regeneration gas heater, and after recovery, it is pumped to the boiler and other places for reuse.

[0042] At present, the focus of coal gas purification patents is the gas purification process itself, while the focus of the utility model is to provide a technical route to reduce sulfur dioxide emissions from steel mill rolling heating furnaces to meet ultra-low emission standards: that is, by analyzing and calculating the composition of the fuel gas used in the steel rolling heating furnace and the sulfur content data brought by different types of gas, the sulfur composition and content of the mixed gas are determined, and then a single gas with the highest sulfur source contribution is selected for deep purification, and then it is mixed, pressurized, and re-mixed with the existing blast furnace gas and converter gas that have not been purified, and finally a complete solution is formed to meet the calorific value required by the hot rolling heating furnace and effectively reduce its sulfur dioxide emissions. The process flow is as follows: Figure 2 shown.

[0043] The utility model adopts the method of deep desulfurization of only coke oven gas before combustion and then mixes it with undesulfurized blast furnace gas / converter gas to supply the steel rolling heating furnace. Compared with the traditional flue gas desulfurization after combustion and the solution of desulfurization of coke oven gas before combustion (mostly only desulfurizing hydrogen sulfide in coke oven gas, without removing or removing a small amount of organic sulfur) and blast furnace gas at the source which has been gradually used in recent years, the utility model has the advantages of small purification device scale, high desulfurization efficiency, low investment and operation cost, easy implementation, etc. It is very suitable for steel mills whose main processes - blast furnace hot blast stove, sintering, coking, self-contained power plant, etc. have met the ultra-low emission requirements and only the steel rolling heat treatment furnace emissions do not meet the standards to achieve ultra-low emission standards for all processes at a relatively small economic cost.

[0044] The utility model has the following beneficial effects: high desulfurization efficiency, environmental protection, reduced investment and low operating cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 This is a schematic diagram of the equipment for source desulfurization of coke oven gas and blast furnace gas in the prior art.

[0046] Figure 2 This is a process flow chart of the utility model.

[0047] Figure 3 It is a structural schematic diagram of the utility model.

[0048] Figure 4 This is a graph showing the relationship between the CS2 hydrolysis conversion efficiency and the temperature when the hydrolysis step is implemented in the utility model.

[0049] Figure 5 It is a comparison chart of SO2 concentration emitted by the heating furnace before and after the implementation of the utility model. DETAILED DESCRIPTION

[0050] The present invention is further described below through specific embodiments. Example

[0051] A device for reducing sulfur dioxide emissions from a steel rolling heating furnace, comprising a pretreatment tower 1, a temperature swing adsorption purification tower 2, a first compressor 3, a first preheater 4, a first hydrolysis tower 5, a second preheater 6, a second hydrolysis tower 7, a cooler 8, a fine desulfurization tower 9, a first coal gas mixing device 10, a second compressor 11, a second coal gas mixing device 12 and a condensate recovery device 13, such as Figure 3 As shown, the specific structure is:

[0052] The inlet of the pretreatment tower 1 is connected to the main pipe of coke oven gas sent to the steel rolling heat treatment furnace, and the outlet of the pretreatment tower 1 is connected to the temperature swing adsorption purification tower 2. The pretreatment tower 1 is filled with a desulfurizer;

[0053] The air inlet of the temperature swing adsorption purification tower 2 is connected to the outlet of the pretreatment tower 1, and the air outlet of the temperature swing adsorption purification tower 2 is connected to the inlet of the first compressor 3;

[0054] The air inlet of the first compressor 3 is connected to the outlet of the temperature swing adsorption purification tower 2, and the air outlet of the first compressor 3 is connected to the first preheater 4.

[0055] The air outlet of the first compressor 3 is also connected to the air inlet of the regeneration gas heater 31, the air outlet of the regeneration gas heater 31 is connected to the air inlet of the temperature swing adsorption purification tower 2, the steam inlet of the regeneration gas heater 31 is connected to the steam source, the water outlet of the regeneration gas heater 31 is connected to the condensed water recovery device 13, and the air inlet and the air outlet of the regeneration gas heater 31 are also connected through a regeneration gas bypass pipeline 32;

[0056] The cold gas inlet of the first preheater 4 is connected to the outlet of the first compressor 3, the cold gas outlet of the first preheater 4 is connected to the first hydrolysis tower 5, the hot gas inlet of the first preheater 4 is connected to the outlet of the second hydrolysis tower 7, and the hot gas outlet of the first preheater 4 is connected to the cooler 8;

[0057] The air inlet of the first hydrolysis tower 5 is connected to the cold gas outlet of the first preheater 4, and the air outlet of the first hydrolysis tower 5 is connected to the gas inlet of the second preheater 6. The catalyst is loaded in the first hydrolysis tower 5;

[0058] The gas inlet of the second preheater 6 is connected to the outlet of the first-stage hydrolysis tower 5, and the gas outlet of the second preheater 6 is connected to the gas inlet of the second-stage hydrolysis tower 7;

[0059] The air inlet of the second-stage hydrolysis tower 7 is connected to the gas outlet of the second preheater 6, and the air outlet of the second-stage hydrolysis tower 7 is connected to the gas inlet of the first preheater 4, and the catalyst is loaded in the second-stage hydrolysis tower 7;

[0060] The air inlet of the cooler 8 is connected to the hot gas outlet of the first preheater 4, and the air outlet of the cooler 8 is connected to the fine desulfurization tower 9.

[0061] The air inlet of the fine desulfurization tower 9 is connected to the outlet of the cooler 8, and the air outlet of the fine desulfurization tower 9 is connected to the first coal gas mixing device 10. The fine desulfurization tower 9 is filled with a carbon-based desulfurizer or an iron oxide-based desulfurizer.

[0062] A bypass pipeline 91 is provided between the inlet of the pretreatment tower 1 and the outlet of the fine desulfurization tower 9. A cut-off valve 92 is provided on the bypass pipeline 91. The cut-off valve 92 is closed during normal production. When other components fail, the cut-off valve 92 is quickly opened, and the coal gas enters the first coal gas mixing device 10 through the bypass pipeline 91.

[0063] The inlet of the first gas mixing device 10 is connected to the outlet of the fine desulfurization tower 9, and the outlet of the first gas mixing device 10 is connected to the second compressor 11.

[0064] The air inlet of the second compressor 11 is connected to the outlet of the first gas mixing device 10, and the air outlet of the second compressor 11 is connected to the second gas mixing device 12.

[0065] The air inlet of the second gas mixing device 12 is connected to the outlet of the second compressor 11, and the air outlet of the second gas mixing device 12 is connected to the main pipe of the mixed gas for the steel rolling heating furnace.

[0066] The condensed water recovery device 13 is connected to the second preheater 6 and the regeneration gas heater 31 .

[0067] In this embodiment:

[0068] There are 8 pretreatment towers 1, and iron oxide-based desulfurizer is loaded in the pretreatment tower 1;

[0069] The first-stage hydrolysis tower 5 and the second-stage hydrolysis tower 7 are both filled with a metal-based catalyst comprising at least one metal element selected from the group consisting of aluminum, titanium and silicon.

[0070] When this embodiment is used, the composition of the fuel gas used in these heating furnaces and the sulfur content brought by different types of gas are first analyzed. The typical fuel structure is:

[0071] Mixed gas calorific value 2400kcal / standard m 3 ,

[0072] Gas ratio: (53.61%~37.66%) blast furnace gas (BFG) + (40.85%~46.39%) coke oven gas (COG) + (0~20%) converter gas (LDG).

[0073] The sulfur components in blast furnace gas are mainly hydrogen sulfide (H2S) and carbonyl sulfide (COS); the sulfides in coke oven gas are mainly carbonyl sulfide (COS), carbon disulfide (CS2), and thiophene (C4H4S). After sampling the gas, the chromatograph is used for detection and analysis, and the sulfur content in the gas is calculated based on the online detection data of SO2 concentration in the heating furnace flue gas. After comprehensive analysis, the typical organic sulfur composition in blast furnace gas and the typical organic sulfur composition in coke oven gas are shown in Table 1 and Table 2 respectively.

[0074] Table 1

[0075]

[0076] Table 2

[0077]

[0078] The total sulfur in the mixed gas is calculated to be 440.86 mg / m 3 ~514.02mg / m 3 (measured in SO2), the sulfur groups contributed by coke oven gas and blast furnace gas are 83.4% to 81.2% and 15.4% to 18.8% respectively. Therefore, the gas with the highest sulfur contribution, coke oven gas, was selected for deep purification, and the required purified gas volume was 200,000 standard m 3 / h.

[0079] Assuming that the blast furnace gas in the mixed gas is not purified, it is calculated that the SO2 concentration of the flue gas emitted by the steel rolling heating furnace using the mixed gas of blast furnace and coke is not higher than 50mg / m 3 (ultra-low emission standard limit), the mixed gas with the highest sulfur content (not mixed with converter gas) is 514.02 mg / m 3 (in terms of SO2), it is calculated that the total sulfur removal rate of coke oven gas must be no less than 71.23%, and the removal rates of the main sulfur components in coke oven gas must be: COS ≥ 90%, CS2 ≥ 80%, H2S ≤ 29 mg / m 3 (measured in SO2).

[0080] After determining the fine desulfurization parameters, the present embodiment is implemented in the following steps:

[0081] Pretreatment: H2S in coke oven gas reacts with desulfurizer and oxygen in pretreatment tower 1 to generate elemental sulfur which is stored in desulfurizer. After desulfurizer is saturated with adsorption, it is replaced. After pretreatment in pretreatment tower 1, H2S content in coke oven gas is reduced to no more than 50mg / m 3 , enters the temperature swing adsorption pretreatment tower 2;

[0082] If the H2S content in the inlet coke oven gas is not higher than 50mg / m 3, the pretreatment step can be omitted and the product can be directly input into the temperature swing adsorption purification tower 2 for temperature swing adsorption.

[0083] Temperature swing adsorption: The coal gas enters the temperature swing adsorption purification tower 2 from the bottom of the tower. The adsorbent filled in the tower selectively adsorbs impurities such as H2S, tar, naphthalene and benzene in the coal gas at room temperature. When the impurities adsorbed by the adsorbent in the temperature swing adsorption purification tower 2 reach saturation, it enters the regeneration process.

[0084] Pressurization: The coke oven gas after removal of impurities such as tar, naphthalene, and benzene is pressurized by the first compressor 3, so that the pressure of the coke oven gas can overcome the resistance drop of the subsequent process section equipment and pipelines.

[0085] Regeneration: During regeneration, a stream of purified gas is taken from the first compressor 1 and connected to the temperature swing adsorption purification tower 2. The purified gas is used as "regeneration gas" and is heated by the regeneration gas heater 31 to desorb impurities in the inner pores of the adsorbent. After regeneration is complete, the regeneration gas is passed through the regeneration gas bypass line 32 to cold-blow the adsorbent bed of the temperature swing adsorption purification tower 2 to reduce it to room temperature. In order to achieve the purpose of continuous production, the temperature swing adsorption purification tower 2 is switched by setting a programmable valve so that multiple towers alternately adsorb and regenerate. After regeneration, the regeneration gas is sent to users such as the boiler equipped with flue gas desulfurization facilities at the end. The heat source of the regeneration gas heater 31 comes from the steam of the off-site pipeline network, and its condensed water is discharged into the condensed water recovery device 13.

[0086] Preheating: In the first preheater 4, the pressurized cold gas exchanges heat with the hot gas from the outlet of the second-stage hydrolysis tower 7. The temperature of the cold gas is increased from 45°C to 60°C to 80°C to 120°C before entering the first-stage hydrolysis tower 5. At the same time, the temperature of the hot gas is reduced from 180°C to about 110°C before entering the cooler 8.

[0087] Hydrolysis: At a temperature of 80°C to 120°C, the organic sulfur components including COS and CS2 in the coke oven gas in the first hydrolysis tower 5 undergo a hydrolysis reaction with the water vapor contained in the gas itself under the action of a catalyst to generate H2S. More than 98% of the COS in the coke oven gas is converted into H2S, and then enters the second preheater 6 and continues to heat up. The following hydrolysis reaction mainly occurs in the first hydrolysis tower 5: COS+H2O=H2S+CO2.

[0088] Preheating: In the second preheater 6, the coal gas after the first stage of hydrolysis exchanges heat with 260℃, 3.2MPa~3.6MPa steam, and the temperature continues to rise from 80℃~120℃ to 110℃~180℃ before entering the second stage hydrolysis tower 7, and the steam condensate is discharged into the condensate recovery device 13.

[0089] Hydrolysis: At a temperature of 110°C to 180°C, CS2 in the coke oven gas in the second-stage hydrolysis tower 7 undergoes a hydrolysis reaction with the water vapor contained in the gas under the action of a catalyst, and about 80% of the CS2 in the coke oven gas is converted into H2S, which then enters the first preheater 4. The following hydrolysis reaction mainly occurs in the second-stage hydrolysis tower 7: CS2+2H2O=2H2S+CO2;

[0090] The relationship between CS2 hydrolysis conversion efficiency and temperature is as follows Figure 4 shown.

[0091] Cooling: After hydrolysis, the coal gas is cooled to room temperature in the cooler 8.

[0092] Fine desulfurization: In the fine desulfurization tower 9, H2S in the coal gas reacts with the desulfurizer and oxygen to generate elemental sulfur which is stored in the desulfurizer. The desulfurizer is replaced after it is saturated with adsorption. The waste desulfurizer can be sent to the sintering unit and mixed with the coarse coke for sintering and then burned.

[0093] Mixing: The coke oven gas that has undergone fine desulfurization and the undesulfurized blast furnace gas from the outside plant pipeline network are mixed in a certain proportion in the first gas mixing device 10, and the mixing is controlled by a flow meter, a flow regulating valve and a calorific value meter.

[0094] Pressurization: The mixed coal gas of high temperature and coke is pressurized by the second compressor 11 so that the pressure of the mixed coal gas can meet the requirements of the rear-end steel rolling heating furnace.

[0095] Mixing: The purified high coke mixed gas is mixed with the converter gas in a certain proportion in the second gas mixing device 12 to make full use of the converter gas. The mixing is controlled by a flow meter, a flow regulating valve and a calorific value meter to form a calorific value of 1800 kcal / m 3 ~2400kcal / standard m 3 The mixed gas is then sent to users of steel rolling heat treatment furnaces outside the boundary through pipelines.

[0096] Condensation: The condensate recovery device 13 collects the steam condensate discharged from the second preheater 6 and the regeneration gas heater 31, and after recovery, it is pumped to the boiler and other places for reuse.

[0097] After adopting this embodiment, the SO2 concentration at each flue gas outlet of the steel rolling heating furnace decreased significantly, with an average decrease of more than 50%, basically below 30 mg / Nm 3 ,like Figure 5 shown.

Claims

1. A device for reducing sulfur dioxide emissions from a steel rolling heating furnace, comprising a pretreatment tower (1), characterized in that: It also includes a temperature swing adsorption purification tower (2), a first compressor (3), a first preheater (4), a first hydrolysis tower (5), a second preheater (6), a second hydrolysis tower (7), a cooler (8), a fine desulfurization tower (9), a first coal gas mixing device (10), a second compressor (11), a second coal gas mixing device (12) and a condensate recovery device (13), The inlet of the pretreatment tower (1) is connected to the main pipe of coke oven gas sent to the steel rolling heat treatment furnace, the outlet of the pretreatment tower (1) is connected to the temperature swing adsorption purification tower (2), and the pretreatment tower (1) is filled with a desulfurizer; The air inlet of the temperature swing adsorption purification tower (2) is connected to the outlet of the pretreatment tower (1), and the air outlet of the temperature swing adsorption purification tower (2) is connected to the inlet of the first compressor (3); The air inlet of the first compressor (3) is connected to the outlet of the temperature swing adsorption purification tower (2), and the air outlet of the first compressor (3) is connected to the first preheater (4). The air outlet of the first compressor (3) is also connected to the air inlet of the regeneration gas heater (31), the air outlet of the regeneration gas heater (31) is connected to the air inlet of the temperature swing adsorption purification tower (2), the steam inlet of the regeneration gas heater (31) is connected to the steam source, the water outlet of the regeneration gas heater (31) is connected to the condensate recovery device (13), and the air inlet and the air outlet of the regeneration gas heater (31) are also connected via a regeneration gas bypass pipeline (32); The cold gas inlet of the first preheater (4) is connected to the outlet of the first compressor (3), the cold gas outlet of the first preheater (4) is connected to the first hydrolysis tower (5), the hot gas inlet of the first preheater (4) is connected to the outlet of the second hydrolysis tower (7), and the hot gas outlet of the first preheater (4) is connected to the cooler (8); The air inlet of the first hydrolysis tower (5) is connected to the cold gas outlet of the first preheater (4), the air outlet of the first hydrolysis tower (5) is connected to the gas inlet of the second preheater (6), and the catalyst is loaded in the first hydrolysis tower (5); The gas inlet of the second preheater (6) is connected to the outlet of the first-stage hydrolysis tower (5), and the gas outlet of the second preheater (6) is connected to the gas inlet of the second-stage hydrolysis tower (7); The air inlet of the second-stage hydrolysis tower (7) is connected to the coal gas outlet of the second preheater (6), the air outlet of the second-stage hydrolysis tower (7) is connected to the coal gas inlet of the first preheater (4), and the catalyst is loaded in the second-stage hydrolysis tower (7); The air inlet of the cooler (8) is connected to the hot coal gas outlet of the first preheater (4), and the air outlet of the cooler (8) is connected to the fine desulfurization tower (9). The air inlet of the fine desulfurization tower (9) is connected to the outlet of the cooler (8), the air outlet of the fine desulfurization tower (9) is connected to the first coal gas mixing device (10), and the fine desulfurization tower (9) is filled with a carbon-based desulfurizer or an iron oxide-based desulfurizer. A bypass pipeline (91) is provided between the inlet of the pretreatment tower (1) and the outlet of the fine desulfurization tower (9), and a cut-off valve (92) is provided on the bypass pipeline (91). The cut-off valve (92) is closed during normal production. When a failure occurs in the equipment 1-9, the cut-off valve (92) is quickly opened, and the coal gas enters the first coal gas mixing device (10) through the bypass pipeline (91); The inlet of the first coal gas mixing device (10) is connected to the outlet of the fine desulfurization tower (9), and the outlet of the first coal gas mixing device (10) is connected to the second compressor (11). The air inlet of the second compressor (11) is connected to the outlet of the first gas mixing device (10), and the air outlet of the second compressor (11) is connected to the second gas mixing device (12). The gas inlet of the second gas mixing device (12) is connected to the outlet of the second compressor (11), and the gas outlet of the second gas mixing device (12) is connected to the main pipe of the mixed gas for the steel rolling heating furnace. The condensate recovery device (13) is connected to the second preheater (6) and the regeneration gas heater (31).

2. The device for reducing sulfur dioxide emissions from a steel rolling heating furnace as claimed in claim 1, characterized in that: There are at least two pretreatment towers (1), and the pretreatment towers (1) are filled with an iron oxide-based desulfurizing agent; The first-stage hydrolysis tower (5) and the second-stage hydrolysis tower (7) are both filled with a metal-based catalyst comprising at least one metal element selected from the group consisting of aluminum, titanium and silicon.

Images