Pretreatment system for prolonging service life of blast furnace gas fine desulfurization hydrolytic agent

Abstract

The utility model relates to a pretreatment system for prolonging the service life of a blast furnace gas fine desulfurization hydrolytic agent, which is characterized in that normal-temperature blast furnace gas is heated by a GGH (gas-gas heater) heat exchanger and then is connected into a special device for integrated mixing and purification of alkali liquor injection; the flue gas passing through the alkali liquor injection integrated mixing and purifying special device exchanges heat with steam in a steam heater, so that the temperature is further increased; the steam is condensed into steam condensate water in the steam heater; steam condensed water is introduced into the alkali liquor tank, and the steam condensed water in the alkali liquor tank is sprayed into a coal gas inlet of the alkali liquor spraying integrated mixing and purifying special device through the alkali liquor spraying and atomizing device. According to the utility model, local materials are used for steam condensate water, meanwhile, after the cold coal gas is heated by the GGH, the water content in the coal gas is in an undersaturated state, then the steam condensate water and alkali liquor are adopted for atomization deacidification, dechlorination and impurity removal, the water consumption is low, a large amount of sewage is not generated, secondary pollution and process energy consumption are not generated, and clean and stable coal gas is provided for the next process.

Description

Technical Field

[0001] The utility model relates to a pretreatment process for fine desulfurization of blast furnace gas, and specifically to a pretreatment system for improving the service life of hydrolysis agent for fine desulfurization of blast furnace gas, belonging to the technical field of fine desulfurization of blast furnace gas. Background Art

[0002] The main components of raw blast furnace gas generated by the blast furnace ironmaking process are: dust, carbon monoxide, carbon dioxide, nitrogen, hydrogen sulfide, organic sulfur (COS, CS2), hydrogen chloride, soluble salts, etc.

[0003] The sulfur in blast furnace gas comes from the furnace burden charged into the blast furnace (such as sinter, coke, pulverized coal, etc.). After high-temperature smelting, about 85 - 90% of the sulfur in the furnace burden enters the blast furnace slag, about 5% is transferred into the hot metal, and only about 10 - 5% is transferred into the blast furnace gas. The formed sulfides are mainly of two types: one is inorganic compounds of sulfur, mainly hydrogen sulfide (H2S), accounting for about 30%; the other is organic compounds of sulfur, such as carbonyl sulfide (COS), carbon disulfide (CS2), etc., among which carbonyl sulfide (COS) accounts for about 70%, and trace amounts of carbon disulfide.

[0004] The chlorine element in blast furnace gas mainly comes from iron-bearing burden, coke and pulverized coal. Only a small amount of chlorine element enters the slag, about 25% enters the dry dedusting ash, and about 60% enters the blast furnace gas.

[0005] In order to solve the corrosion problem of the gas main pipe caused by impurities (salts, HCl, etc.) in blast furnace gas, there are two common practices in the iron and steel metallurgy industry:

[0006] 1) Set up a separate water washing tower, spray a large amount of alkaline solution (liquid-gas ratio 0.6 - 0.7 L / m3) for water washing. After the external drainage is precipitated with medicine, it is recycled. Problems: Due to the large amount of water sprayed, the equipment investment of the water washing tower is high; the water treatment system is huge, and salts in the recycled water are continuously enriched, further deteriorating the saturation concentration of impurities (salts, HCl, etc.) in the gas, and more likely to cause scaling and corrosion of the gas pipeline.

[0007] 2) Spray alkali at multiple levels (liquid-gas ratio 0.05 - 0.2 L / m3) on the gas pipeline for water washing, and the external drainage is transported and treated by tanker. Problems: Since the partial pressure of water vapor in the gas after passing through the TRT (equipment for generating electricity by utilizing the residual pressure of blast furnace top gas) has reached the saturation equilibrium state, a small amount of water washing cannot break through the double electric layer on the surface of existing impurities (dust, salts, HCl, etc.), and it basically enters the gas condensate system in the form of liquid mechanical water in the gas, unable to achieve the goal of impurity and salt removal, and instead affecting the normal combustion of the user's burner. Content of the Utility Model

[0008] The purpose of the present utility model is to meet the technical requirements of fine desulfurization of blast furnace gas, and in combination with the fluctuations of impurity components in blast furnace gas and the characteristics of steam condensate that can be utilized in the fine desulfurization process of blast furnace gas, to provide a pretreatment method and system that can make use of local materials, has a simple process, obvious impurity removal effect, and can extend the service life of the hydrolysis agent for fine desulfurization of blast furnace gas.

[0009] The present utility model adopts the following technical solutions:

[0010] A pretreatment method for extending the service life of the hydrolysis agent for fine desulfurization of blast furnace gas. After the blast furnace gas at normal temperature is heated and raised in temperature by a GGH heat exchanger, it is connected to a special device for integrated mixing and purification by alkali liquid injection; the flue gas after passing through the special device for integrated mixing and purification by alkali liquid injection exchanges heat with steam in a steam heater to further increase the temperature; the steam condenses into steam condensate in the steam heater; the steam condensate is connected to an alkali liquid tank, and the steam condensate in the alkali liquid tank is sprayed into the gas inlet of the special device for integrated mixing and purification by alkali liquid injection through an alkali liquid injection atomization device 1.

[0011] Preferably, a circle of the alkali liquid injection atomization device 1 is arranged radially along the periphery of the pipeline at the gas inlet.

[0012] Preferably, a metering device is added to the alkali liquid tank.

[0013] Preferably, after being heated by the steam heater, the temperature of the blast furnace gas is ≥60°C.

[0014] A pretreatment system for extending the service life of the hydrolysis agent for fine desulfurization of blast furnace gas, including a GGH heat exchanger, a steam condensate injection atomization device, an alkali liquid tank, and a special device for integrated mixing and purification by alkali liquid injection; the special device for integrated mixing and purification by alkali liquid injection is arranged after the GGH heat exchanger and before the steam heater. The steam condensate injection atomization device uses steam condensate and alkali liquid as the media for acid removal and impurity removal, and mixes the alkali liquid in the alkali liquid tank with the steam condensate and then atomizes and sprays it into the gas inlet of the special device for integrated mixing and purification by alkali liquid injection.

[0015] Preferably, the special device for integrated mixing and purification of alkali solution spraying is in the shape of a cylinder, which includes a liquid spraying and atomizing device 1, a sinusoidal sieve 2, a demisting device 3, and a flushing device 4; the liquid spraying and atomizing device 1 is installed around the gas inlet; the sinusoidal sieve 2 is installed obliquely downward in front of the gas inlet passage; the demisting device 3 is installed horizontally above the gas inlet and covers the entire cross-section of the cylinder; the flushing device 4 is arranged above the demisting device 3 with the flushing direction downward; gas flow direction: the gas first mixes with the alkali solution of the liquid spraying and atomizing device 1, enters the special device, collides and filters with the sinusoidal sieve 2, then enters the fixed-bed demisting device 3, and finally enters the steam heater of the next process from the gas outlet; the flow direction of mechanical water, dust and salts: the gas first mixes and coalesces with the alkali solution of the liquid spraying and atomizing device 1, enters the special device and collides with the sinusoidal sieve 2, large particles of mechanical water, dust and salts sink into the sewage hopper of the special device under the action of gravity, and fine particles enter the demisting device 3 with the gas for further purification and dehydration. The demisting device 3 is regularly flushed with water, and the sewage in the sewage hopper is discharged regularly.

[0016] Preferably, the gas outlet at the top and the sewage outlet at the bottom of the cylinder are both conical.

[0017] Preferably, the sinusoidal sieve has a multi-layer sieve surface structure. When the gas flow impacts the sieve surface, its warp or weft fluctuates like a string.

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

[0019] 1) The steam condensate of the steam heat exchanger is a waste generated in the process of gas fine desulfurization. Its temperature is 80 - 90°C and its quality is deionized soft water (or pure water); therefore, the present utility model uses local materials and will not increase the impurity content in the gas as the gas washing water; the spraying process is simple and reliable, with low material and energy consumption, low production cost, and no three wastes pollution in the production process.

[0020] 2) According to the gas fine desulfurization process, after the cold gas is heated by the GGH, the temperature difference is more than 10°C, and the saturated water content in the gas increases by about 20 g / m 3 Above, the liquid-gas ratio of the completely atomized sprayed alkali solution can reach 0.02 L / m 3 , so that the water content in the gas is in an undersaturated state, and the steam condensate and alkali solution atomization are used for acid removal, chlorine removal and impurity removal, with less water consumption, no large amount of sewage generated, no secondary pollution and process energy consumption, and providing clean and stable gas for the next process (such as gas desulfurization of hydrogen sulfide; realizing anti-corrosion protection of gas pipelines, etc.).

[0021] 3) The sine screen at the inlet of the special integrated mixing and purification device for lye injection efficiently collides and coalesces mechanical water, dust, and salts in the coal gas, with high removal efficiency and a simple device; the demisting device at the outlet ensures that the mechanical water content in the coal gas entering the heater is ≤ 75 mg / m 3 , which has no impact on the subsequent processes.

[0022] 4) The special integrated mixing and purification device for lye injection can remove H2S in the coal gas with an efficiency of over 30%, which can reduce the filling amount of desulfurization adsorbent or extend the service life of the desulfurization adsorbent;

[0023] 5) The special integrated mixing and purification device for lye injection removes acidic impurities (H2S), chlorine (such as HCl), and salts in the coal gas, and at the same time also has an effect on removing dust in the coal gas; the remaining gaseous basic substances in the coal gas play a role in repairing and activating the basic active sites of the hydrolysis agent, which can extend the service life of the hydrolysis agent.

[0024] 6) The steam condensation injection atomization device uses micro-mist lye injection, which does not reduce the temperature of the coal gas. The removal efficiency of H2S in the coal gas can reach over 30%, reducing the filling amount of desulfurization adsorbent or extending the service life of the desulfurization adsorbent.

[0025] 7) The amount of steam condensate generated by the heating exchanger is matched with the completely atomized water volume of lye injection. The molar flow ratio (R) of H2O and COS in the coal gas can be controlled within an appropriate range, which has no poisoning effect on the hydrolysis agent; the condensate water generated by the special integrated mixing and purification device enters the coal gas water seal water and is regularly discharged; the spraying and washing process is simple and reliable, with low material and energy consumption and extremely low production cost, and there is no pollution of the three wastes during the process.

[0026] 8) The sine screen in the special integrated mixing and purification device is a multi-layer screen surface structure. When the air flow impacts the screen surface, its warp or weft fluctuates like a string, increasing the collision probability between fine dust, salts, and micro-mist, and improving the effects of dust removal, desalination, deacidification, and demisting. Description of the Drawings

[0027] Figure 1 is a flow chart of the pretreatment method for improving the service life of the hydrolysis agent for fine desulfurization of blast furnace gas in the present invention.

[0028] Figure 2 is a structural schematic diagram of the special integrated mixing and purification device for lye injection in the pretreatment system for improving the service life of the hydrolysis agent for fine desulfurization of blast furnace gas in the present invention.

[0029] In the figure, 1. Lye injection atomization device, 2. Sine screen, 3. Demisting device, 4. Flushing device. Detailed Embodiments

[0030] The present invention will be further described below in conjunction with the drawings and specific embodiments.

[0031] The GGH heat exchanger (flue gas - flue gas reheater) is a device used in the limestone - gypsum wet flue gas desulfurization system of thermal power plants. Its main functions are to increase the flue gas discharge temperature and lifting height to improve the effect of flue gas emission, and at the same time recover thermal energy.

[0032] See Figure 1 , a pretreatment method for prolonging the service life of the hydrolysis agent for fine desulfurization of blast furnace gas. After the normal - temperature blast furnace gas is heated and raised in temperature by the GGH heat exchanger, it is connected to a special integrated device for alkali - liquid injection and mixed purification; the flue gas after passing through the special integrated device for alkali - liquid injection and mixed purification exchanges heat with steam in a steam heater to further increase the temperature; the steam condenses into steam condensate in the steam heater; the steam condensate is connected to an alkali - liquid tank, and the steam condensate in the alkali - liquid tank is sprayed into the gas inlet of the special integrated device for alkali - liquid injection and mixed purification through an alkali - liquid injection atomization device 1.

[0033] In this embodiment, see Figure 2 , a circle of the alkali - liquid injection atomization device 1 is arranged radially along the periphery of the pipeline at the gas inlet.

[0034] In this embodiment, see Figure 1 , a metering device is added to the alkali - liquid tank.

[0035] In this embodiment, after being heated by the steam heater, the temperature of the blast furnace gas is ≥60°C.

[0036] Continue to see Figure 1 , a pretreatment system for prolonging the service life of the hydrolysis agent for fine desulfurization of blast furnace gas, including a GGH heat exchanger, a steam condensate injection atomization device, an alkali - liquid tank, and a special integrated device for alkali - liquid injection and mixed purification; the special integrated device for alkali - liquid injection and mixed purification is arranged after the GGH heat exchanger and before the steam heater. The steam condensate injection atomization device uses steam condensate and alkali - liquid as the media for acid removal and impurity removal, and mixes the alkali - liquid in the alkali - liquid tank with the steam condensate and then atomizes and sprays it into the gas inlet of the special integrated device for alkali - liquid injection and mixed purification.

[0037] In this embodiment, see Figure 2, the special device for integrated mixing and purification of alkali solution injection is in the shape of a cylinder, which includes a liquid injection and atomization device 1, a sine screen 2, a demisting device 3, and a flushing device 4; the liquid injection and atomization device 1 is installed around the gas inlet; the sine screen 2 is installed obliquely downward in front of the gas inlet passage; the demisting device 3 is installed horizontally above the gas inlet and covers the entire cross-section of the cylinder; the flushing device 4 is arranged above the demisting device 3, and the flushing direction is downward; gas flow direction: the gas first mixes with the alkali solution of the liquid injection and atomization device 1, enters the special device, collides and filters with the sine screen 2, then enters the fixed bed demisting device 3, and finally enters the steam heater of the next process from the gas outlet; the flow direction of mechanical water, dust and salts: the gas first mixes and coagulates with the alkali solution of the liquid injection and atomization device 1, enters the special device and collides with the sine screen 2, the large-particle mechanical water, dust and salts sink into the sewage hopper of the special device under the action of gravity, and the fine particles enter the demisting device 3 with the gas for further purification and dehydration. The demisting device 3 is regularly flushed with water, and the sewage in the sewage hopper is discharged regularly.

[0038] In this embodiment, refer to Figure 2 , the gas outlet at the top and the sewage outlet at the bottom of the cylinder are both conical.

[0039] In this embodiment, continue to refer to Figure 2 , the sine screen has a multi-layer screen surface structure. When the air flow hits the screen surface, its warp or weft fluctuates like a string.

[0040] In Figure 1 , before the blast furnace gas from the pipe network enters the special device for integrated mixing and purification of alkali solution injection, it is first heated up by the GGH heat exchanger. The purpose is to use the high-temperature gas before entering the cooler to exchange heat with the cold gas, causing a temperature difference between the inlet and outlet of the cold gas, making the water vapor in the gas in an undersaturated state, which helps the fine mist of the injected alkali solution to quickly wet and coagulate with impurities such as dust and salts in the integrated mixing and purification special device, and no large amount of mechanical water will be generated.

[0041] It should be noted that:

[0042] Figure 1 , the steam condensate in is generated in the heater process and normally needs to be discharged and treated. This method can directly utilize the local materials without increasing the production cost after utilization. The spraying and washing process is simple and reliable, with low material and energy consumption and low production cost, and there is no pollution of the three wastes in the production process.

[0043] Figure 1 , the lowest temperature in the hydrolysis tower process of the blast furnace gas should not be less than 60 °C at present, and the temperature in the desulfurization tower process is at normal temperature (30 - 40 °C). The GGH heat exchanger uses the hot and cold gases in the process for gas-gas heat exchange, which is an energy-saving configuration for the fine desulfurization of gas.

[0044] In Figure 2 the front view of the special pretreatment device for prolonging the service life of the hydrolysis agent for fine desulfurization of blast furnace gas shown in the figure, an alkali liquid spraying and atomizing device 1 is arranged on the gas inlet pipeline, a sine screen 2 is arranged at the inlet of the special device, a demisting device 3 is arranged at the outlet, and a flushing device 4 is arranged above the demisting device 3.

[0045] Gas flow direction: The gas first mixes with the alkali liquid of the alkali liquid spraying and atomizing device 1, enters the special device, collides and filters with the sine screen 2, then enters the fixed bed demisting device 3, and finally enters the next process (steam heater) from the gas outlet.

[0046] Flow directions of mechanical water, dust and salts: The gas first mixes and coalesces with the alkali liquid of the alkali liquid spraying and atomizing device 1, enters the special device and collides with the sine screen 2. Large particles of mechanical water, dust and salts sink into the sewage hopper of the special device under the action of gravity, and fine particles enter the demisting device 3 together with the gas for further purification and dehydration. The demisting device 3 is regularly flushed with water, and the sewage in the sewage hopper is discharged regularly.

[0047] In the prior art, as introduced in the background art part, the alkali liquid spraying is generally arranged before the GGH heat exchanger, while in the present invention, it is arranged after the GGH heat exchanger. According to the fine desulfurization process of blast furnace gas, after the cold gas is heated by the GGH, the temperature difference is more than 10°C, and the water content in the saturated state in the gas increases by about 20 g / m 3 Above, the liquid-gas ratio for complete atomization of the sprayed alkali liquid can reach 0.02 L / m 3 , so that the water content in the gas is in an undersaturated state. Moreover, steam condensate and alkali liquid atomization are used for acid removal, chlorine removal and impurity removal, with less water consumption, no large amount of sewage generated, no secondary pollution and process energy consumption, and providing clean and stable gas for the next process (such as removing hydrogen sulfide from gas; realizing anti-corrosion protection of gas pipelines, etc.).

[0048] The sine screen at the inlet of the alkali liquid spraying integrated mixing and purification special device efficiently collides and coalesces mechanical water, dust and salts in the gas, with high removal efficiency and a simple device; the demisting device at the outlet ensures that the mechanical water content in the gas entering the heater is ≤ 75 mg / m 3 , without affecting the subsequent process.

[0049] The alkali liquid spraying integrated mixing and purification special device can remove H2S in the gas with an efficiency of more than 30%, which can reduce the filling amount of the desulfurization adsorbent or prolong the service life of the desulfurization adsorbent;

[0050] The special device for integrated lye injection mixing and purification removes acidic impurities (H2S), dechlorinates (such as HCl), and salts in the coal gas, and also has an effect on removing dust in the coal gas; the residual gaseous basic substances in the coal gas play a role in repairing and promoting the activation of the basic active sites of the hydrolysis agent, which can extend the service life of the hydrolysis agent.

[0051] The steam condensation injection atomization device uses micro-mist lye injection without reducing the temperature of the coal gas. The removal efficiency of H2S in the coal gas can reach more than 30%, reducing the filling amount of the desulfurization adsorbent or extending the service life of the desulfurization adsorbent.

[0052] The amount of steam condensate generated by the heating exchanger is matched with the fully atomized water volume of the lye injection. The molar flow ratio (R) of H2O and COS in the coal gas can be controlled within an appropriate range, which has no poisoning effect on the hydrolysis agent; the condensate water generated by the integrated mixing and purification special device enters the coal gas water seal water and is regularly discharged; the spraying process is simple and reliable, with low material and energy consumption and extremely low production cost, and there is no pollution of the three wastes during the process.

[0053] The sine screen in the integrated mixing and purification special device is a multi-layer screen surface structure. When the air flow impacts the screen surface, its warp or weft fluctuates like a string, increasing the collision probability between fine dust, salts and micro-mist, and improving the dust removal, desalination, deacidification and demisting effects.

[0054] The utility model can be widely used in the pretreatment method and device for fine desulfurization of blast furnace gas in iron and steel metallurgy enterprises, ensuring the stable operation of fine desulfurization of blast furnace gas and extending the service life of the hydrolysis agent for fine desulfurization of blast furnace gas.

[0055] The above are the preferred embodiments of the utility model. Those of ordinary skill in the art can also make various transformations or improvements on this basis. Without departing from the general concept of the utility model, these transformations or improvements should all fall within the scope of protection required by the utility model.

Claims

1. A pretreatment system for increasing the life of a blast furnace gas desulfurization hydrolyzing agent, characterized in that: It includes GGH heat exchanger, steam condensation spray atomization device, alkali liquid tank, and alkali liquid spray integrated mixing purification special device; The alkali liquid injection integrated mixing purification device is set after the GGH heat exchanger and before the steam heater. The steam condensation spray atomization device uses steam condensate and alkali solution as deacidification and impurity removal media, and mixes the alkali solution in the alkali solution tank with the steam condensate and then sprays it into the gas inlet of the alkali solution spray integrated mixing purification special device.

2. The pretreatment system for prolonging the life of the blast furnace gas fine desulfurization hydrolyzing agent according to claim 1, characterized in that: The alkali liquid injection integrated mixing purification device is in the shape of a cylinder, and comprises a liquid injection atomization device (1), a sinusoidal screen (2), a demisting device (3), and a flushing device (4); The liquid spray atomization device (1) is installed around the gas inlet; The sinusoidal screen (2) is installed in front of the gas inlet passage in a manner that it is tilted downward; The demisting device (3) is installed transversely above the gas inlet and covers the entire cross section of the cylinder; The flushing device (4) is arranged above the demisting device (3), and the flushing direction is downward; Gas flow: The gas is first mixed with the alkali solution of the alkali solution spray atomization device (1), enters a special device, collides and filters with the sinusoidal screen (2), then enters the fixed bed demisting device (3), and finally enters the steam heater of the next process from the gas outlet; Flow direction of mechanical water, dust and salt: the coal gas is first mixed with the alkali solution of the alkali solution spray atomization device (1) and condensed, and then enters the special device to collide with the sinusoidal screen (2). Large particles of mechanical water, dust and salt sink into the sewage hopper of the special device under the action of gravity, and fine particles enter the demisting device (3) together with the coal gas for further purification and dehydration. The demisting device (3) is regularly flushed with water, and the sewage in the sewage hopper is regularly discharged.

3. The pretreatment system for prolonging the life of the blast furnace gas fine desulfurization hydrolyzing agent according to claim 2, characterized in that: The gas outlet at the top and the sewage outlet at the bottom of the cylinder are both conical.

4. The pretreatment system for prolonging the life of the blast furnace gas fine desulfurization hydrolyzing agent according to claim 1, characterized in that: The sinusoidal screen has a multi-layer screen surface structure. When the airflow hits the screen surface, its warp or weft lines fluctuate like strings.

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