Fine desulfurization pretreatment system for blast furnace gas

Abstract

The invention relates to the technical field of smelting equipment, and particularly provides a blast furnace gas fine desulfurization pretreatment system which comprises a secondary dechlorination device and a hydrolysis catalysis device, the secondary dechlorination device comprises a secondary dechlorination pretreatment agent, and the hydrolysis catalysis device comprises a hydrolysis catalyst. An outlet of the secondary dechlorination device is communicated with an inlet of the hydrolysis catalysis device; the secondary dechlorination pretreatment agent comprises the following components in percentage by mass: 85%-90% of a first carrier, 1%-10% of a first active component and 5%-10% of a pore forming agent; the hydrolysis catalyst comprises the following components in percentage by mass: 80%-90% of a second carrier, 1%-5% of a second active component and 5%-15% of a pore forming agent. The problems that a COS hydrolysis catalyst is short in service life and low in hydrolysis conversion rate can be solved.

Description

Technical Field

[0001] The invention relates to the technical field of smelting equipment, and in particular to a blast furnace gas fine desulfurization pretreatment system. Background Art

[0002] During the blast furnace ironmaking process, sulfur, chlorine and other elements contained in iron ore, sintered ore, coke and coal will react with other substances to generate carbonyl sulfide COS, H2S and HCl, etc., which enter the blast furnace gas. Blast furnace gas containing COS and H2S will generate sulfur dioxide during the combustion process. Desulfurization of blast furnace gas can effectively reduce the sulfur dioxide generated during the combustion of blast furnace gas, playing a role in source control.

[0003] H2S in blast furnace gas easily reacts with alkali solution and is absorbed, while COS is an organic sulfur and is difficult to react with alkali solution. In industry, COS is usually removed by using a catalyst to hydrolyze COS into H2S and then reacting with alkali solution. However, the catalyst for catalyzing COS hydrolysis will have a shortened service life and a low COS hydrolysis conversion rate after a period of use. In current industrial applications, new catalysts are usually replaced after the conversion efficiency decreases. Frequent replacement of COS hydrolysis catalysts will increase the operating costs of blast furnace gas desulfurization and increase the desulfurization cost. Summary of the invention

[0004] In order to solve the problems of short service life and low hydrolysis conversion rate of COS hydrolysis catalyst, the present invention provides a blast furnace gas fine desulfurization pretreatment system, and adopts the following technical scheme:

[0005] A blast furnace gas fine desulfurization pretreatment system, comprising a secondary dechlorination device and a hydrolysis catalytic device, wherein the secondary dechlorination device comprises a secondary dechlorination pretreatment agent, the hydrolysis catalytic device comprises a hydrolysis catalyst, and the outlet of the secondary dechlorination device is connected to the inlet of the hydrolysis catalytic device;

[0006] The secondary dechlorination pretreatment agent comprises the following components in percentage by mass: 85%-90% of a first carrier, 1%-10% of a first active component and 5%-10% of a pore-forming agent;

[0007] The hydrolysis catalyst comprises the following components in percentage by mass: 80%-90% of a second carrier, 1%-5% of a second active component and 5%-15% of a pore former;

[0008] Among them, the first carrier is a γ-Al2O3-based carrier, the second carrier includes a γ-Al2O3-based carrier and titanium dioxide, the first active component is potassium oxide, and the second active component includes one or more of sodium salt, potassium salt and barium oxide.

[0009] Optionally, the second active component comprises 70-80% potassium salt, 10-20% sodium salt and 1-5% barium oxide;

[0010] Optionally, the pore-forming agent includes one or more of sesbania powder, higher alcohols and carboxymethyl cellulose.

[0011] Optionally, the secondary dechlorination pretreatment agent is a strip structure, and the cross-sectional diameter of the secondary dechlorination pretreatment agent is 4-6 mm.

[0012] Optionally, the hydrolysis catalyst is a spherical structure, and the diameter of the hydrolysis catalyst is 5-7 mm.

[0013] Optionally, the secondary dechlorination pretreatment agent is prepared by the following method:

[0014] Mixing and grinding the first carrier and the first active component to obtain a first mixed powder;

[0015] dissolving the pore-forming agent in water to obtain a pore-forming agent solution;

[0016] adding the pore-forming agent solution into the first mixed powder until the first mixed powder is agglomerated, and extruding the agglomerated first mixed powder to obtain a strip-shaped catalyst carrier;

[0017] The strip catalyst carrier is dried and calcined to obtain a secondary dechlorination pretreatment agent.

[0018] Optionally, the mass ratio of the first carrier and the first active component is (3.5-4.5):1.

[0019] Optionally, the temperature for drying the strip-shaped catalyst carrier is 120-140°C, and the temperature for calcining the strip-shaped catalyst carrier is 450-600°C.

[0020] Optionally, the hydrolysis catalyst is prepared by the following method:

[0021] dissolving the pore-forming agent in water to obtain a pore-forming agent solution;

[0022] The second carrier and the titanium dioxide are mixed and ground to obtain a second mixed powder, the pore-forming agent solution is sprayed on the surface of the second mixed powder, and the second mixed powder is made into a spherical catalyst carrier;

[0023] dissolving the second active component in water to obtain an active solution, and immersing the spherical catalyst carrier in the active solution;

[0024] The impregnated spherical catalyst carrier is dried and calcined to obtain a hydrolysis catalyst.

[0025] Optionally, the mass ratio of the second carrier to the titanium dioxide is (3.5-5.5):1.

[0026] Optionally, the impregnation time of the spherical catalyst carrier is 1-3 hours, the drying temperature of the spherical catalyst carrier is 120-140°C, and the calcination temperature of the spherical catalyst carrier is 500-630°C.

[0027] Optionally, the blast furnace gas fine desulfurization pretreatment system further includes a primary dechlorination device, and the outlet of the primary dechlorination device is connected to the inlet of the secondary dechlorination device;

[0028] The primary dechlorination device comprises a spraying component and a primary dechlorination agent, and the spraying component is used for spraying the primary dechlorination agent onto blast furnace gas.

[0029] Optionally, the blast furnace gas fine desulfurization pretreatment system further includes a heating device, which is arranged at the inlet end of the spraying member and the hydrolysis catalytic device.

[0030] Optionally, the blast furnace gas fine desulfurization pretreatment system further includes a bag dust removal device, and the bag dust removal device is arranged between the primary dechlorination device and the secondary dechlorination device;

[0031] Optionally, the blast furnace gas fine desulfurization pretreatment system further includes a chlorine element detection device, which is arranged at the inlet end of the spraying component, and the primary dechlorination device further includes a primary dechlorination regulating valve and a controller, and the primary dechlorination regulating valve and the chlorine element detection device are electrically connected to the controller respectively;

[0032] The chlorine element detection device is used to detect the chlorine content of the blast furnace gas at the inlet end of the spraying component, and the controller is used to control the opening of the first-level dechlorination regulating valve according to the chlorine content of the blast furnace gas at the inlet end of the spraying component.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] The present invention pre-treats the blast furnace gas by setting a secondary dechlorination device before the catalytic reaction of the blast furnace gas hydrolysis, specifically using potassium oxide with a γ-Al2O3 base as a carrier as a catalyst to remove hydrogen chloride in the blast furnace gas, thereby reducing the influence of hydrogen chloride on the hydrolysis link. Furthermore, in the hydrolysis catalytic device, potassium salt with a γ-Al2O3 base as a carrier and modified by titanium dioxide is used as a hydrolysis catalyst to complete the catalytic hydrolysis process of the blast furnace gas. Experimental demonstration shows that the catalyst combination system and process of the present invention can significantly improve the dechlorination effect and hydrolysis conversion rate of the blast furnace gas, extend the service life of the hydrolysis catalyst, and reduce the fine desulfurization operation cost of the blast furnace gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Schematic diagram of a blast furnace gas fine desulfurization pretreatment system according to an embodiment of the present invention;

[0036] Figure 2 is a graph showing the relationship between the chlorine capacity of the CuO catalyst and temperature;

[0037] Figure 3 is a curve diagram showing the relationship between the chlorine capacity and temperature of the secondary dechlorination pretreatment agent in an embodiment of the present invention;

[0038] Figure 4 It is a curve diagram showing the relationship between the chlorine capacity and chlorine content of the CuO catalyst;

[0039] Figure 5 is a curve diagram showing the relationship between the chlorine capacity and the chlorine content of the secondary dechlorination pretreatment agent in an embodiment of the present invention;

[0040] Figure 6 It is the relationship curve between the chlorine capacity and space velocity of CuO catalyst;

[0041] Figure 7 It is a curve diagram showing the relationship between the chlorine capacity and the space velocity of the secondary dechlorination pretreatment agent in the embodiment of the present invention.

[0042] Description of reference numerals:

[0043] 1. Primary dechlorination device; 11. Spraying parts; 12. Air inlet valve; 13. Primary dechlorination regulating valve; 14. Metering pump; 15. Silo; 16. Controller; 2. Secondary dechlorination device; 3. Hydrolysis catalytic device; 4. Heating device; 5. Bag dust removal device; 6. Bypass line; 61. Bypass line shut-off valve; 7. Chlorine element detection device; 8. Carbonyl sulfide first detection device; 9. Carbonyl sulfide second detection device; 10. CEMS detection device. DETAILED DESCRIPTION

[0044] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. Although certain embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be interpreted as being limited to the embodiments described herein. On the contrary, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the drawings and embodiments of the present invention are only for exemplary purposes and are not intended to limit the scope of protection of the present invention.

[0045] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as those commonly understood by those skilled in the art to which this application belongs; the terms used in the specification of this application are only for the purpose of describing specific implementation methods and are not intended to limit this application;

[0046] The term "including" and its variations used in this article are open inclusions, that is, "including but not limited to"; the term "based on" is "based at least in part on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one other embodiment"; the term "some embodiments" means "at least some embodiments"; the term "optionally" means "optional embodiments". The relevant definitions of other terms will be given in the following description. It should be noted that the concepts of "first" and "second" mentioned in the present invention are used to distinguish different objects, rather than to describe a specific order or a primary and secondary relationship. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, the meaning of "multiple" is two or more.

[0047] Blast furnace gas is a combustible gas produced as a byproduct during the blast furnace ironmaking process. Recycling and making good use of blast furnace gas has high economic and environmental benefits. The specific process route of blast furnace gas fine desulfurization technology is blast furnace gas pretreatment + organic sulfur conversion + wet oxidation desulfurization. The inventors found that when performing organic sulfur conversion, in the presence of chlorine, the catalyst catalyzing the hydrolysis of carbonyl sulfide is prone to deactivation, and its service life will be greatly shortened, which further increases the replacement frequency of the carbonyl sulfide hydrolysis catalyst, thereby increasing the operating cost of blast furnace gas desulfurization. Therefore, the dechlorination effect of blast furnace gas has an important influence on its hydrolysis catalytic effect.

[0048] In order to solve the problem of short service life of carbonyl sulfide hydrolysis catalyst due to deactivation of chlorine in coal gas, and to improve the dechlorination effect of blast furnace gas and carbonyl sulfide hydrolysis conversion rate, the embodiment of the present invention provides a blast furnace gas fine desulfurization pretreatment system. Figure 1 As shown, the system includes a secondary dechlorination device 2 and a hydrolysis catalytic device 3. The secondary dechlorination device 2 includes a secondary dechlorination pretreatment agent, the hydrolysis catalytic device 3 includes a hydrolysis catalyst, and the outlet of the secondary dechlorination device 2 is connected to the inlet of the hydrolysis catalytic device 3.

[0049] The secondary dechlorination pretreatment agent comprises the following components in mass percentage: 85%-90% of a first carrier, 1%-10% of a first active component and 5%-10% of a pore-forming agent; the hydrolysis catalyst comprises the following components in mass percentage: 80%-90% of a second carrier, 1%-5% of a second active component and 5%-15% of a pore-forming agent; wherein the first carrier is aluminum oxide, the second carrier comprises aluminum oxide and titanium dioxide, the first active component is potassium oxide, and the second active component comprises one or more of sodium salt, potassium salt and barium oxide.

[0050] In the embodiment of the present invention, before the catalytic reaction of blast furnace gas hydrolysis, the blast furnace gas is pretreated by a secondary dechlorination device 2, specifically, potassium oxide with a γ-Al2O3 base as a carrier is used as a catalyst to remove hydrogen chloride in the blast furnace gas, thereby reducing the influence of hydrogen chloride on the hydrolysis link. And further, in the hydrolysis catalytic device 3, potassium salt with a γ-Al2O3 base as a carrier modified by titanium dioxide is used as a hydrolysis catalyst to complete the catalytic hydrolysis process of the blast furnace gas. It has been experimentally demonstrated that the use of the catalyst combination system in the embodiment of the present invention can significantly improve the dechlorination effect and hydrolysis conversion rate of blast furnace gas, extend the service life of the hydrolysis catalyst, and reduce the operating cost of fine desulfurization of blast furnace gas.

[0051] In some optional embodiments, the secondary dechlorination device 2 and the hydrolysis catalytic device 3 can both be in the form of a reaction tower, and the secondary dechlorination pretreatment agent and the hydrolysis catalyst are respectively loaded in the corresponding reaction tower. In the secondary dechlorination pretreatment agent and the hydrolysis catalyst, the aluminum oxide in the first carrier and the second carrier can be specifically γ-Al2O3, the first active component can be specifically K2O, and the second active component includes 70-80% potassium salt, 10-20% sodium salt and 1-5% barium oxide, wherein the potassium salt can be K2CO3, and the sodium salt can be Na2CO3. The pore-forming agent can be one or more of sesbania powder, high carbon alcohol and carboxymethyl cellulose.

[0052] In the embodiment of the present invention, γ-Al2O3-supported alkaline oxide is used as a secondary dechlorination pretreatment agent. Experiments have shown that, compared with conventional metal oxide pretreatment agents, the secondary dechlorination pretreatment agent in the embodiment of the present invention has a higher chlorine capacity under specific environmental conditions, and can effectively adsorb hydrogen chloride, making the dechlorination reaction more complete. The hydrolysis catalyst in the embodiment of the present invention can significantly improve the hydrolysis conversion rate of carbonyl sulfide in blast furnace gas under specific conditions such as space velocity and temperature.

[0053] In some optional embodiments, the secondary dechlorination pretreatment agent is a strip structure, the cross-sectional diameter of the secondary dechlorination pretreatment agent is 4-6 mm, and the hydrolysis catalyst is a spherical structure, the diameter of the hydrolysis catalyst is 5-7 mm. The diameters of the secondary dechlorination pretreatment agent and the hydrolysis catalyst in the embodiment of the present invention are both in the millimeter level, and the strip and spherical structural settings can increase the contact area between the pretreatment agent and the blast furnace gas, which is more conducive to the dechlorination reaction and the hydrolysis catalytic reaction.

[0054] In some optional embodiments, the secondary dechlorination pretreatment agent is prepared by the following method:

[0055] S11: Mix and grind the first carrier and the first active component to obtain a first mixed powder. Specifically, the mass ratio of the first carrier and the first active component when mixed can be (3.5-4.5): 1. At the same time, dissolve the pore-forming agent in water to obtain a pore-forming agent solution.

[0056] S12: slowly adding the pore-forming agent solution to the first mixed powder until the first mixed powder is agglomerated. Then the agglomerated first mixed powder is extruded into strips to obtain a strip catalyst carrier. Specifically, the mass ratio of the pore-forming agent solution to the first mixed powder can be 1:(1-3).

[0057] S13: drying the strip catalyst carrier at 120-140° C. for 4-5 hours, and then calcining at 450-600° C. for 4-6 hours to obtain a secondary dechlorination pretreatment agent.

[0058] In some optional embodiments, the hydrolysis catalyst is prepared by the following method:

[0059] S21: dissolving the pore-forming agent in water to obtain a pore-forming agent solution, and mixing and grinding the second carrier and titanium dioxide to obtain a second mixed powder. Specifically, the mass ratio of the second carrier and titanium dioxide when mixed can be (3.5-5.5): 1. Then, while spraying the pore-forming agent solution on the surface of the second mixed powder, the second mixed powder is made into a spherical catalyst carrier.

[0060] S22: dissolving the second active component in water to obtain an active solution, and immersing the spherical catalyst carrier obtained in step S21 in the active solution. The second active component may include 70-80% potassium salt, 10-20% sodium salt and 1-5% barium oxide, wherein the potassium salt may be K2CO3, the sodium salt may be Na2CO3, and the immersion time may be 1-3 hours.

[0061] S23: drying the impregnated spherical catalyst carrier at 120-140° C. for 3-5 h, and then calcining at 500-630° C. for 4-6 h to obtain a hydrolysis catalyst.

[0062] In some optional embodiments, referring to Figure 1 As shown, the blast furnace gas fine desulfurization pretreatment system also includes a primary dechlorination device 1, and the outlet of the primary dechlorination device 1 is connected to the inlet of the secondary dechlorination device 2 through a main pipeline. Figure 1 As shown, the primary dechlorination device 1 includes a spraying component 11 and a primary dechlorination agent. The spraying component 11 can be specifically arranged on the main pipe to spray the primary dechlorination agent onto the blast furnace gas in the main pipe.

[0063] Optionally, the primary dechlorination agent may be baking soda powder, preferably baking soda powder of 800 mesh. The spraying member 11 may be a high-pressure nozzle.

[0064] Optionally, refer to Figure 1 As shown, the primary dechlorination device 1 further includes a silo 15, a metering pump 14, a primary dechlorination regulating valve 13 and an air inlet valve 12, and the silo 15, the metering pump 14, the primary dechlorination regulating valve 13, the air inlet valve 12 and the spraying part 11 are sequentially connected. The silo 15 is used to provide the primary dechlorination agent to the spraying part 11, the air inlet valve 12 and the primary dechlorination regulating valve 13 are used to control the connection between the silo 15 and the spraying part 11, and the metering pump 14 is used to display the spraying amount of the primary dechlorination agent.

[0065] The embodiment of the present invention can perform preliminary dechlorination on blast furnace gas by further providing a primary dechlorination device 1, can alleviate the dechlorination pressure of the secondary dechlorination device 2, and can also avoid the adverse effect of excessive chlorine content on the secondary dechlorination pretreatment agent by preliminarily reducing the chlorine content of the blast furnace gas, which is beneficial to improving the dechlorination effect of the secondary dechlorination pretreatment agent.

[0066] Optionally, refer to Figure 1 As shown, the inlet end of the spraying member 11 is also provided with a heating device 4, which is arranged on the main pipeline and is used to heat the blast furnace gas. The heating device 4 automatically starts and stops according to the blast furnace gas temperature of the main pipeline, and automatically starts when the primary dechlorination device 1 is working and the blast furnace gas temperature is lower than 100°C, so as to ensure that the gas temperature adapts to the reaction conditions of the primary dechlorination device 1. In other embodiments, since the temperature of the blast furnace gas will drop after the primary dechlorination and the secondary dechlorination, in order to meet the temperature requirements of the hydrolysis catalysis, the inlet end of the hydrolysis catalysis device 3 can also be provided with a heating device 4 so that the hydrolysis temperature of the blast furnace gas meets the requirements.

[0067] Optional, see Figure 1 As shown, the blast furnace gas fine desulfurization pretreatment system also includes a bag dust removal device 5, which is arranged between the primary dechlorination device 1 and the secondary dechlorination device 2. The bag dust removal device 5 is used to remove dust from the blast furnace gas after the primary dechlorination to remove impurities such as baking soda powder mixed in the blast furnace gas.

[0068] Optionally, refer to Figure 1 As shown, the blast furnace gas fine desulfurization pretreatment system also includes a bypass pipeline 6, one end of the bypass pipeline 6 is connected to the inlet end of the secondary dechlorination device 2, and the other end is connected to the outlet end of the hydrolysis catalytic device 3. A bypass pipeline shut-off valve 61 is provided on the bypass pipeline 6, and correspondingly, a shut-off valve is also provided between each device on the main pipeline. The setting of the bypass pipeline 6 is conducive to controlling the opening and closing of the secondary dechlorination device 2 and the hydrolysis catalytic device 3 according to the chlorine content in the blast furnace gas, thereby increasing the adjustable function of the system.

[0069] Optionally, refer to Figure 1As shown, the blast furnace gas fine desulfurization pretreatment system also includes a chlorine element detection device 7, which is arranged at the inlet end of the spraying part 11, specifically at the inlet end of the heating device 4 at the inlet of the spraying part 11. Further, the primary dechlorination device 1 also includes a controller 16, and the chlorine element detection device 7, the primary dechlorination regulating valve 13 and the air intake valve 12 are electrically connected to the controller 16 respectively. The chlorine element detection device 7 is used to detect the chlorine content of the blast furnace gas at the inlet end of the spraying part 11, and the controller 16 is used to control the opening of the primary dechlorination regulating valve 13 according to the chlorine content of the blast furnace gas at the inlet end of the spraying part 11, so as to adjust the injection amount of the spraying part 11.

[0070] The present invention detects the chlorine content in the blast furnace gas at the inlet end of the primary dechlorination device 1 by means of a chlorine element detection device 7. If the detected value of the chlorine content is less than a set value, the primary dechlorination regulating valve 13 and the air intake valve 12 are controlled to be in a closed state, and the blast furnace gas passes through the secondary dechlorination device 2 and the hydrolysis catalytic device 3 in sequence to complete the catalytic conversion; if the chlorine content in the blast furnace gas at the inlet end of the primary dechlorination device 1 is greater than or equal to the set value, the primary dechlorination regulating valve 13 and the air intake valve 12 are controlled to be in an open state, and the opening of the primary dechlorination regulating valve 13 is controlled according to the chlorine content value, and the blast furnace gas passes through the primary dechlorination device 1, the secondary dechlorination device 2 and the hydrolysis catalytic device 3 in sequence to complete the catalytic conversion.

[0071] Specifically, in the blast furnace gas fine desulfurization pretreatment process, the set value can be 5 mg / Nm3. The present invention can select different process modes according to the chlorine content through the above control process, and maximize the reduction of operating costs while adapting to different working conditions.

[0072] Optionally, refer to Figure 1 As shown, the blast furnace gas fine desulfurization pretreatment system also includes a first carbonyl sulfide detection device 8, a second carbonyl sulfide detection device 9 and a CEMS detection device 10. The first carbonyl sulfide detection device 8 is used to detect the carbonyl sulfide content in the blast furnace gas before secondary dechlorination, the second carbonyl sulfide detection device 9 is used to detect the carbonyl sulfide content in the blast furnace gas after secondary dechlorination, and the CEMS detection device 10 is used to perform comprehensive detection of various pollutants in the blast furnace gas after hydrolysis.

[0073] Optionally, the blast furnace gas fine desulfurization pretreatment process further includes: the temperature of the blast furnace gas at the inlet end of the primary dechlorination device 1 is not less than 100° C., and the temperature of the blast furnace gas at the inlet end of the hydrolysis catalytic device 3 is not less than 90° C. Specifically, the temperature can be controlled by the heating device 4. When the blast furnace gas is under the above temperature conditions, it has better dechlorination effect and hydrolysis catalytic effect.

[0074] The present invention is described in detail below through specific examples and comparative examples:

[0075] Example 1

[0076] (I) Preparation of secondary dechlorination pretreatment agent

[0077] The following steps are used to prepare the secondary dechlorination pretreatment agent:

[0078] S11: γ-Al2O3 and K2O are mixed and ground in a mass ratio of 3.5:1 to obtain a first mixed powder. At the same time, sesbania powder is dissolved in water to obtain a pore-forming agent solution.

[0079] S12: slowly adding the pore-forming agent solution into the first mixed powder until the first mixed powder is agglomerated, and then extruding the agglomerated first mixed powder into strips to obtain a strip-shaped catalyst carrier.

[0080] S13: drying the strip catalyst carrier at 120° C. for 5 h, and then calcining at 450° C. for 6 h to obtain a secondary dechlorination pretreatment agent.

[0081] (II) Preparation of hydrolysis catalyst

[0082] S21: dissolving a high carbon alcohol in water to obtain a pore-forming agent solution, and mixing and grinding γ-Al2O3 and titanium dioxide in a mass ratio of 3.5:1 to obtain a second mixed powder. Then, while spraying the pore-forming agent solution on the surface of the second mixed powder, the second mixed powder is rolled into a spherical catalyst carrier.

[0083] S22: dissolving the second active component in water to obtain an active solution, wherein the second active component comprises 75% K2CO3, 20% Na2CO3 and 5% barium oxide by mass percentage. Then, the spherical catalyst carrier obtained in step S21 is immersed in the active solution for 2 hours.

[0084] S23: The impregnated spherical catalyst carrier is first dried at 140° C. for 3 h, and then calcined at 500° C. for 6 h to obtain a hydrolysis catalyst.

[0085] After testing, the average cross-sectional diameter of the secondary dechlorination pretreatment agent is 4.2 mm, specifically including 85% γ-Al2O3, 10% K2O and 5% sesbania powder. The average diameter of the hydrolysis catalyst is 6.5 mm, specifically including 62% γ-Al2O3, 21% titanium dioxide, 1.5% K2CO3, 0.4% Na2CO3, 0.1% barium oxide and 15% high-carbon alcohol. The physical properties of the secondary dechlorination pretreatment agent, the hydrolysis catalyst and the CuO catalyst were tested and compared, and the comparison results are shown in Table 1:

[0086] Table 1 Comparison of physical properties of various catalysts

[0087]

[0088] As can be seen from Table 1, compared with conventional CuO catalysts, the secondary dechlorination pretreatment agent and the hydrolysis catalyst in the embodiment of the present invention have higher specific surface area, pore volume and pore diameter. This shows that the secondary dechlorination pretreatment agent in the embodiment of the present invention has a larger reaction area with blast furnace gas, thereby improving the reaction efficiency.

[0089] (III) Comparative experiment on the factors affecting the chlorine capacity of secondary dechlorination pretreatment agent and CuO catalyst

[0090] Prepare blast furnace gas. The blast furnace gas includes the following components: 22.1% CO, 17.4% CO2, 56.3% N2, 3.8% H2, 0.2% O2, 0.2% CH4, 20mg / Nm3H2S, 80mg / Nm3COS, 5mg / Nm3CS2, at normal pressure and air velocity of 2000h -1 、The concentration of imported HCL is 1000~1050mg / m 3 Under the conditions of 35℃ saturated water vapor, the relationship between the chlorine capacity and temperature of conventional CuO catalyst and secondary dechlorination pretreatment agent was investigated. The results are as follows Figure 2-3 As shown. Among them, Figure 2 The relationship between the chlorine capacity of CuO catalyst and temperature is shown in the figure. Figure 3 This is a curve diagram showing the relationship between the chlorine capacity and temperature of the secondary dechlorination pretreatment agent.

[0091] Depend on Figure 2 It can be seen that the chlorine capacity of the CuO catalyst gradually decreases with the increase of temperature, reaching the lowest chlorine capacity of 16.8% at 100°C, and then gradually increases with the increase of temperature. The main reason is that at low temperatures, the bed adsorbs water, and the hydrogen chloride in the gas phase first combines with water, ionizes hydrogen ions and chloride ions, and can quickly react with metal oxides. When the temperature rises from 60°C to 100°C, the water adsorbed by the bed gradually decreases, reducing the ability of the bed to capture and adsorb hydrogen chloride, causing the hydrogen chloride and pretreatment agent to gradually change from liquid-solid reaction to gas-solid reaction, resulting in low chlorine capacity. When the bed temperature is higher than 100°C, the number of activated molecules increases, the binding force between hydrogen chloride and the protective agent increases, the reaction rate also increases, the reaction is more complete, and the chlorine capacity increases accordingly.

[0092] Depend on Figure 3 It can be seen that the chlorine capacity of the secondary dechlorination pretreatment agent decreases slowly with the increase of temperature, reaching a minimum chlorine capacity of 10.2% at 100°C, and then gradually increases slowly with the increase of temperature, and the maximum and minimum chlorine capacity values ​​are within 0.5%. Therefore, within this temperature range, the chlorine tolerance value of the secondary dechlorination pretreatment agent is small, and compared with conventional metal oxide catalysts, it has significant advantages of high precision and stable chlorine capacity.

[0093] Furthermore, at normal pressure and airspeed of 20000h-1 The relationship between the chlorine capacity and chlorine content of conventional CuO catalyst and secondary dechlorination pretreatment agent was investigated under the conditions of reaction temperature of 120℃ and 35℃ saturated water vapor. The results are as follows Figure 4-5 As shown. Among them, Figure 4 The relationship curve between the chlorine capacity and chlorine content of CuO catalyst is shown in Fig. Figure 5 This is a curve diagram showing the relationship between the chlorine capacity and chlorine content of the secondary dechlorination pretreatment agent.

[0094] Depend on Figure 4 It can be seen that the chlorine capacity of the CuO catalyst gradually decreases with the increase of the chlorine content in the blast furnace gas, and the chlorine capacity gradually decreases from 17.4% to 15.2%, and the rate of decrease tends to increase with the increase of chlorine concentration. The reason is that when the catalyst bed is working, the upper layer is the saturated zone where the chlorine capacity reaches the saturated state, the middle layer is the unsaturated mass transfer zone that is being dechlorinated, and the lower layer is the clean zone that is not dechlorinated. With the increase of hydrogen chloride content in the gas phase, the reaction kinetics of CuO and hydrogen chloride gradually changes from diffusion control to reaction activation energy control. As the chlorine content in the gas phase increases, the hydrogen chloride reaction is not complete, resulting in an increase in the mass transfer layer of the catalyst and a corresponding decrease in the clean zone, and the penetration chlorine capacity decreases accordingly.

[0095] Depend on Figure 5 It can be seen that the chlorine capacity of the secondary dechlorination pretreatment agent decreases with the increase of the chlorine content in the blast furnace gas, but it only gradually decreases from 10.3% to 9.5%, and the decrease is small. This shows that the reaction rate of the secondary dechlorination pretreatment agent in the embodiment of the present invention with hydrogen chloride gas is faster, and the chlorine content of the blast furnace gas is 10-100 mg / m 3 The thickness of the mass transfer layer is relatively small, and hydrogen chloride can be basically completely reacted under this condition. Therefore, compared with the conventional CuO catalyst, the penetration chlorine capacity of the secondary dechlorination pretreatment agent in the present invention is less affected by the chlorine content.

[0096] Furthermore, at normal pressure, reaction temperature of 120°C, and blast furnace gas inlet concentration of 1000-1050 mg / m 3 Under the conditions of saturated water vapor at 35℃, the relationship between the chlorine capacity and space velocity of the secondary dechlorination pretreatment agent and CuO catalyst was investigated. The results are as follows Figure 6-7 As shown. Among them, Figure 6 The relationship between the chlorine capacity and space velocity of CuO catalyst is shown in the figure. Figure 7 This is a curve diagram showing the relationship between the chlorine capacity and space velocity of the secondary dechlorination pretreatment agent.

[0097] Depend on Figure 6It can be seen that the chlorine capacity of the CuO catalyst gradually decreases with the increase of the space velocity. The reason is that with the increase of the space velocity, the residence time of hydrogen chloride in the bed gradually decreases, which is not conducive to the full contact of the gas-solid reaction. The contact probability between hydrogen chloride and the active components of the CuO catalyst gradually decreases, the mass transfer layer gradually increases, and the penetration chlorine capacity decreases.

[0098] Depend on Figure 7 It can be seen that the secondary dechlorination pretreatment agent in the present invention is less affected by the space velocity. As the space velocity increases, the chlorine capacity gradually decreases from 10.7% to 10.2%, and the chlorine capacity changes slightly. This shows that the secondary dechlorination pretreatment agent in the present invention has a relatively stable treatment capacity for blast furnace gas.

[0099] Through the comparison of the above experimental data, it can be found that the secondary dechlorination pretreatment agent prepared by the present invention is not easily affected by changes in conditions such as temperature, gas composition and air velocity, and has the advantage of being more stable under working conditions with large fluctuations in blast furnace gas.

[0100] (III) Experiment on factors affecting the hydrolysis conversion rate of hydrolysis catalyst

[0101] At a reaction temperature of 90°C, atmospheric pressure, saturated water at room temperature, CO2 content of 10%, and inlet COS concentration of 100 mg / m 3 500h -1 、1000h -1 , 2000h -1 The hydrolysis conversion rates of the hydrolysis catalyst of the present invention and the D504 type normal temperature COS hydrolysis catalyst at the same space velocity are shown in Table 2:

[0102] Table 2 Hydrolysis conversion of two hydrolysis catalysts at different space velocities

[0103]

[0104] It can be seen from Table 2 that the hydrolysis catalyst in the embodiment of the present invention is -1 and 1000h -1 In the case of , the hydrolysis conversion rate is 100%, but at a space velocity of 2000h -1 Under these conditions, the hydrolysis conversion rate was reduced to 95.2%. However, the D504 room temperature COS hydrolysis catalyst was -1 At a space velocity of 500 h, the hydrolysis conversion rate dropped to below 100%. This shows that the hydrolysis catalyst in the embodiment of the present invention has -1 -1000h -1 Under the space velocity condition, the hydrolysis conversion rate is more stable.

[0105] Furthermore, at an airspeed of 1000 h -1, normal pressure, normal temperature saturated water vapor, CO2 content is 10%, inlet COS concentration is 100mg / m 3 The hydrolysis conversion rates of the hydrolysis catalyst of the present invention and the D504 type normal temperature COS hydrolysis catalyst at 60-150° C. were investigated under the conditions of , and the results are shown in Table 3:

[0106] Table 3 Hydrolysis conversion of two hydrolysis catalysts at different temperatures

[0107]

[0108] As shown in Table 3, the hydrolysis conversion rate of the hydrolysis catalyst is 100% when the temperature is greater than 90°C, while the D504 normal temperature COS hydrolysis catalyst can maintain a 100% hydrolysis conversion rate at a temperature of less than 100°C. When the temperature reaches 120°C, the hydrolysis conversion rate drops to 97%, and when the temperature reaches 150°C, the hydrolysis conversion rate drops to 93%. In actual industry, the temperature of blast furnace gas before and after TRT power generation is usually between 80-150°C, and the most common is between 90-120°C. It can be seen that the hydrolysis catalyst in the embodiment of the present invention can better adapt to the actual operating temperature of blast furnace gas and has a more stable hydrolysis conversion rate at the operating temperature of blast furnace gas.

[0109] Further, at a reaction temperature of 90°C and a space velocity of 1000 h -1 , atmospheric pressure, saturated water vapor at room temperature, CO2 content of 10%, the hydrolysis catalyst of the present invention and the D504 type normal temperature COS hydrolysis catalyst were investigated at inlet COS concentrations of 50 mg / m 3 , 100mg / m 3 and 285 mg / m 3 The hydrolyzing agent conversion rate under the conditions of . The results are shown in Table 4:

[0110] Table 4 Hydrolysis conversion of two hydrolysis catalysts at different COS concentrations

[0111]

[0112] It can be seen from Table 4 that the hydrolysis catalyst in the present invention has a COS concentration of 50 mg / m 3 and 100 mg / m 3 The hydrolysis conversion rate under the conditions was 100%, indicating that when the COS concentration was 100 mg / m 3 Within this range, the hydrolysis catalysts can show extremely high reactivity even when the COS concentration reaches 200 mg / m 3 The hydrolysis conversion rate can also be maintained above 98%. The D504 room temperature COS hydrolysis catalyst can maintain a COS concentration of 100 mg / m 3When the hydrolysis conversion rate drops below 100%, the COS concentration is ≤100mg / m 3 Therefore, the hydrolysis catalyst in the present invention can ensure that the system has a more stable fine desulfurization effect under the actual working conditions of blast furnace gas.

[0113] At a reaction temperature of 90°C and a space velocity of 1000 h -1 , normal pressure, CO2 content is 10%, inlet COS concentration is 100mg / m 3 The hydrolysis agent conversion rates of the hydrolysis catalyst of the present invention and the D504 type normal temperature COS hydrolysis catalyst at different water vapor contents were investigated under the conditions of , and the results are shown in Table 5:

[0114] Table 5 Hydrolysis conversion of two hydrolysis catalysts at different water vapor contents

[0115]

[0116] As shown in Table 5, when the water vapor content is ≤2, the hydrolysis conversion rate of the hydrolysis catalyst in the embodiment of the present invention is greater than 99%, and when the water vapor content is ≤10%, the hydrolysis agent conversion rate can be maintained above 95%. Compared with the D504 type normal temperature COS hydrolysis catalyst, at the same water vapor content, the hydrolysis catalyst in the present invention has a relatively higher hydrolysis conversion rate.

[0117] Further, the reaction temperature was 90°C, atmospheric pressure, and the space velocity was 1000 h -1 , saturated water vapor at room temperature, CO2 content is 10%, and the inlet COS concentration is 100 mg / m 3 The conversion rates of the two hydrolysis catalysts at different Cl- contents were investigated under the conditions of , and the results are shown in Table 6:

[0118] Table 6 Different Cl - Hydrolysis conversion rate of hydrolysis catalyst under

[0119]

[0120]

[0121] As shown in Table 6, the influence of chloride ions on the hydrolysis activity of the two hydrolysis catalysts is relatively large, and the hydrolysis activity of the hydrolysis catalysts decreases with the increase of chloride ion content. Specifically, when the chlorine content is 5%, the hydrolysis conversion rate of the hydrolysis catalyst in the present invention is reduced to 95.4%, and the D504 type normal temperature COS hydrolysis catalyst is reduced to less than 90%. When the chlorine content is 10%, the hydrolysis catalyst conversion rate in the present invention is reduced to 90.6%, and the D504 type normal temperature COS hydrolysis catalyst is reduced to 80.4%. It can be seen that compared with conventional hydrolysis catalysts, the influence of chloride ion content on the hydrolysis activity of the hydrolysis catalyst in the present invention is relatively smaller.

[0122] The primary dechlorination device 1, the secondary dechlorination device 2 and the hydrolysis catalytic device 3 are connected in sequence to form a blast furnace gas fine desulfurization pretreatment system, and the primary dechlorination device 1 uses baking soda powder as the primary dechlorination agent, the secondary dechlorination device 2 uses the secondary dechlorination pretreatment agent prepared in (I) of this embodiment, and the hydrolysis catalytic device 3 uses the hydrolysis catalyst prepared in (II) of this embodiment. At normal pressure, an air velocity of 20000h-1, a reaction temperature of 120°C, 35°C saturated water vapor, the HCL concentration of the imported blast furnace gas is 1000-1050mg / m 3 The temperature of the blast furnace gas entering the primary dechlorination device 1 is controlled to be 120°C, and the temperature of the blast furnace gas entering the hydrolysis catalytic device 3 is controlled to be 100°C.

[0123] Comparative Example 1

[0124] The difference between this comparative example and Example 1 is that the CuO catalyst is used as the secondary dechlorination pretreatment agent in the secondary dechlorination device 2 .

[0125] Comparative Example 2

[0126] The difference between this comparative example and Example 1 is that the hydrolysis catalytic device 3 uses a D504 type room temperature COS hydrolysis catalyst.

[0127] The blast furnace gas fine desulfurization pretreatment system was operated for one month, and during the operation, the gas components at the inlet and outlet of the hydrolysis catalytic device 3 were detected by the second carbonyl sulfide detection device 9 and the CEMS detection device 10. It was found through detection that the carbonyl sulfide content in the gas at the outlet of the hydrolysis catalytic device 3 in Example 1 of the present invention was maintained below 5.2% within one month, and the chlorine content was maintained below 1.8%, while the carbonyl sulfide content in the gas at the outlet of the hydrolysis catalytic device 3 in Comparative Example 1 gradually increased on the 15th day and reached 10.5% on the 20th day, and correspondingly, the chlorine content gradually increased on the 10th day and reached 20.3% on the 15th day. The maximum chlorine content of the gas at the outlet of the hydrolysis catalytic device 3 in Comparative Example 2 was 4.2% within one month, and the carbonyl sulfide content began to increase on the 20th day and reached 8.5% on the 30th day.

[0128] It can be seen that the use of the blast furnace gas fine desulfurization pretreatment system and catalyst combination process in the embodiment of the present invention can simultaneously improve the dechlorination effect and hydrolysis conversion rate of blast furnace gas.

[0129] Although the present invention is disclosed as above, the protection scope of the present invention is not limited thereto. Those skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will fall within the protection scope of the present invention.

Claims

1. A blast furnace gas fine desulfurization pretreatment system, characterized in that: The invention comprises a secondary dechlorination device (2) and a hydrolysis catalytic device (3), wherein the secondary dechlorination device (2) comprises a secondary dechlorination pretreatment agent, the hydrolysis catalytic device (3) comprises a hydrolysis catalyst, and the outlet of the secondary dechlorination device (2) is connected to the inlet of the hydrolysis catalytic device (3); The secondary dechlorination pretreatment agent comprises the following components in percentage by mass: 85%-90% of a first carrier, 1%-10% of a first active component and 5%-10% of a pore-forming agent; The hydrolysis catalyst comprises the following components in percentage by mass: 80%-90% of a second carrier, 1%-5% of a second active component and 5%-15% of a pore former; Among them, the first carrier is a γ-Al2O3-based carrier, the second carrier includes a γ-Al2O3-based carrier and titanium dioxide, the first active component is potassium oxide, and the second active component includes one or more of sodium salt, potassium salt and barium oxide.

2. The blast furnace gas fine desulfurization pretreatment system according to claim 1 is characterized in that: The second active component comprises 70-80% potassium salt, 10-20% sodium salt and 1-5% barium oxide; And / or, the pore-forming agent includes one or more of sesbania powder, higher carbon alcohol and carboxymethyl cellulose.

3. The blast furnace gas fine desulfurization pretreatment system according to claim 1 is characterized in that: The secondary dechlorination pretreatment agent is in a strip structure, and the cross-sectional diameter of the secondary dechlorination pretreatment agent is 4-6 mm; And / or, the hydrolysis catalyst is a spherical structure, and the diameter of the hydrolysis catalyst is 5-7 mm.

4. The blast furnace gas fine desulfurization pretreatment system according to claim 1, characterized in that: The secondary dechlorination pretreatment agent is prepared by the following method: Mixing and grinding the first carrier and the first active component to obtain a first mixed powder; dissolving the pore-forming agent in water to obtain a pore-forming agent solution; adding the pore-forming agent solution into the first mixed powder until the first mixed powder is agglomerated, and extruding the agglomerated first mixed powder to obtain a strip-shaped catalyst carrier; The strip-shaped catalyst carrier is dried and calcined to obtain the secondary dechlorination pretreatment agent.

5. The blast furnace gas fine desulfurization pretreatment system according to claim 4 is characterized in that: The mass ratio of the first carrier and the first active component is (3.5-4.5):1; And / or, the temperature for drying the strip-shaped catalyst carrier is 120-140°C, and the temperature for calcining the strip-shaped catalyst carrier is 450-600°C.

6. The blast furnace gas fine desulfurization pretreatment system according to claim 1, characterized in that: The hydrolysis catalyst is prepared by the following method: dissolving the pore-forming agent in water to obtain a pore-forming agent solution; The second carrier and the titanium dioxide are mixed and ground to obtain a second mixed powder, the pore-forming agent solution is sprayed on the surface of the second mixed powder, and the second mixed powder is made into a spherical catalyst carrier; dissolving the second active component in water to obtain an active solution, and immersing the spherical catalyst carrier in the active solution; The impregnated spherical catalyst carrier is dried and calcined to obtain the hydrolysis catalyst.

7. The blast furnace gas fine desulfurization pretreatment system according to claim 6, characterized in that: The mass ratio of the second carrier to the titanium dioxide is (3.5-5.5):1; And / or, the impregnation time of the spherical catalyst carrier is 1-3 hours, the drying temperature of the spherical catalyst carrier is 120-140°C, and the calcination temperature of the spherical catalyst carrier is 500-630°C.

8. The blast furnace gas fine desulfurization pretreatment system according to claim 1, characterized in that: It also includes a primary dechlorination device (1), wherein the outlet of the primary dechlorination device (1) is connected to the inlet of the secondary dechlorination device (2); The primary dechlorination device (1) comprises a spraying component (11) and a primary dechlorination agent, and the spraying component (11) is used to spray the primary dechlorination agent onto blast furnace gas.

9. The blast furnace gas fine desulfurization pretreatment system according to claim 8, characterized in that: It also includes a heating device (4), which is arranged at the inlet end of the spraying member (11) and the hydrolysis catalytic device (3); And / or, the blast furnace gas fine desulfurization pretreatment system further comprises a bag dust removal device (5), and the bag dust removal device (5) is arranged between the primary dechlorination device (1) and the secondary dechlorination device (2).

10. The blast furnace gas fine desulfurization pretreatment system according to claim 8, characterized in that: It also includes a chlorine element detection device (7), which is arranged at the inlet end of the spraying member (11). The primary dechlorination device (1) also includes a primary dechlorination regulating valve (13) and a controller (16). The primary dechlorination regulating valve (13) and the chlorine element detection device (7) are electrically connected to the controller (16) respectively. The chlorine element detection device (7) is used to detect the chlorine content of the blast furnace gas at the inlet end of the spraying component (11), and the controller (16) is used to control the opening of the primary dechlorination regulating valve (13) according to the chlorine content of the blast furnace gas at the inlet end of the spraying component (11).

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