Blast furnace gas fine desulfurization unit and system thereof

Abstract

The utility model relates to the technical field of gas desulfurization, in particular to a blast furnace gas fine desulfurization unit and a system thereof, the unit comprises a washing tower, a heater, a hydrolysis tower, a cooler and a desulfurization tower which are connected in sequence, the heater is used for heating the washed blast furnace gas; the hydrolysis tower is used for carrying out hydrolysis treatment on the heated blast furnace gas so as to convert organic sulfur into hydrogen sulfide; the cooler is used for cooling the hydrolyzed blast furnace gas; and the desulfurizing tower is used for removing hydrogen sulfide in the cooled blast furnace gas. After blast furnace gas is treated by the washing tower, most acidic components in the blast furnace gas can be removed, then the blast furnace gas enters the hydrolysis tower after being heated by the heater so as to improve the efficiency of converting organic sulfur into hydrogen sulfide, and the blast furnace gas enters the desulfurization tower after being cooled by the cooler so as to remove most hydrogen sulfide in the blast furnace gas. Therefore, fine desulfurization of the blast furnace gas is realized.

Description

Technical Field

[0001] The utility model relates to the technical field of gas desulfurization, in particular to a fine desulfurization unit and system for blast furnace gas. Background Art

[0002] As one of the most important secondary energy sources in iron and steel enterprises, blast furnace gas has a wide range of uses. However, when used as fuel for combustion heating, sulfur dioxide in the flue gas emissions is likely to pollute the atmospheric environment and is an important part of atmospheric environmental pollution such as acid rain. At present, the desulfurization of such flue gas generally adopts the end-treatment method, which has high engineering land occupation, investment and operation costs. The source treatment through blast furnace gas desulfurization is the most ideal and currently advocated environmental treatment technology.

[0003] The fine desulfurization technology of blast furnace gas is a source treatment technology for treating organic sulfur (mainly carbonyl sulfide) and inorganic sulfur (mainly hydrogen sulfide) in blast furnace gas. The key lies in the control and reduction of carbonyl sulfide (COS) in the gas. Carbonyl sulfide is a carbon compound structurally similar to carbon disulfide. The gaseous carbonyl sulfide molecule is linear, with stable properties. It is difficult to directly react with other compounds in the anaerobic environment of blast furnace gas, and the absorption efficiency of alkaline solution is relatively low. Generally, in the removal of carbonyl sulfide from industrial gases, carbonyl sulfide is first converted into hydrogen sulfide (H2S), and then further treated by removing hydrogen sulfide.

[0004] The conversion of carbonyl sulfide mainly includes hydrogenolysis and adsorption processes. The hydrogenolysis reaction has a relatively good conversion effect on carbonyl sulfide in blast furnace gas, but the hydrogenation treatment requires the use of highly active catalysts and high-temperature and high-pressure conditions, with high feasibility difficulties. For the adsorption and removal process of carbonyl sulfide, molecular sieves or microcrystalline material adsorbents are usually used, and the adsorbent needs to be desorbed frequently. Moreover, the desorption requires a relatively high temperature, and there are problems such as long adsorbent purging time, uneven heating, and low heating efficiency. Summary of the Utility Model

[0005] The purpose of the utility model is to provide a fine desulfurization unit and system for blast furnace gas to solve the problem of fine desulfurization of existing blast furnace gas.

[0006] To achieve the above purpose, the utility model provides a fine desulfurization unit for blast furnace gas, which includes a washing tower, a heater, a hydrolysis tower, a cooler and a desulfurization tower connected in sequence, wherein:

[0007] The washing tower is used for washing blast furnace gas to remove acidic gas in the blast furnace gas;

[0008] The heater is used for heating the washed blast furnace gas;

[0009] The hydrolysis tower is used to perform hydrolysis treatment on the heated blast furnace gas to convert the organic sulfur in the blast furnace gas into hydrogen sulfide;

[0010] The cooler is used to cool down the blast furnace gas after the hydrolysis treatment;

[0011] The desulfurization tower is used to remove hydrogen sulfide from the cooled blast furnace gas.

[0012] Optionally, the scrubbing tower uses water or alkaline solution to scrub the blast furnace gas.

[0013] Optionally, the fine desulfurization unit of the blast furnace gas further includes a heat exchanger. The two ends of the heating side of the heat exchanger are respectively connected to the scrubbing tower and the heater, and the two ends of the cooling side of the heat exchanger are respectively connected to the hydrolysis tower and the cooler.

[0014] Optionally, the heat exchange elements of the heat exchanger and the heating elements of the heater are both made of corrosion-resistant materials.

[0015] Optionally, the fine desulfurization unit of the blast furnace gas further includes a demister disposed between the scrubbing tower and the heat exchanger. The demister is used to remove the liquid water in the scrubbed blast furnace gas.

[0016] Optionally, the fine desulfurization unit of the blast furnace gas further includes a pretreatment tower disposed between the heater and the hydrolysis tower. The pretreatment tower is used to remove the halogen components in the blast furnace gas.

[0017] Optionally, the temperature of the blast furnace gas entering the hydrolysis tower is between 80°C and 100°C.

[0018] Optionally, the temperature of the blast furnace gas entering the desulfurization tower is between 35°C and 50°C.

[0019] Based on the same inventive concept, the present utility model also provides a fine desulfurization system for blast furnace gas, including at least two parallelly arranged fine desulfurization units for blast furnace gas as described above.

[0020] Optionally, the fine desulfurization unit of the blast furnace gas further includes a demister disposed between the scrubbing tower and the heat exchanger. All the fine desulfurization units for blast furnace gas share one scrubbing tower and one demister.

[0021] In the fine desulfurization unit for blast furnace gas and its system provided by the present utility model, there are at least one of the following beneficial effects:

[0022] 1) After the blast furnace gas is treated by the scrubber, most of the acidic components in the blast furnace gas can be removed. Then, it enters the hydrolysis tower after being heated by the heater to improve the efficiency of the conversion of organic sulfur to hydrogen sulfide. After being cooled by the cooler, it enters the desulfurization tower to efficiently remove most of the hydrogen sulfide in the blast furnace gas, thus realizing the fine desulfurization of the blast furnace gas.

[0023] 2) By adding a heat exchanger to exchange heat between the high-temperature gas after hydrolysis and the low-temperature gas before entering the heater, not only can the low-temperature gas be heated once, but also the high-temperature gas after hydrolysis can be cooled once. That is, through the heat exchange between the high-temperature gas and the low-temperature gas, the heat energy can be recycled within the system, thereby reducing the system energy consumption.

[0024] 3) By adding a demister between the existing demister between the scrubber and the heat exchanger, the liquid water in the blast furnace gas can be effectively removed, which can not only reduce the corrosion of the system caused by the dissolution of acidic gases in water, but also reduce the energy consumption of subsequent gas heating.

[0025] 4) By adding a pretreatment tower between the heater and the hydrolysis tower, the halogen components such as fluorine and chlorine in the blast furnace gas can be further removed, providing a relatively clean raw material gas for hydrolysis and desulfurization, and reducing the adverse effects of halogen components on the hydrolysis catalyst and desulfurization catalyst. Description of the Drawings

[0026] Those of ordinary skill in the art should understand that the provided drawings are used to better understand the present invention and do not constitute any limitation to the scope of the present invention. Among them:

[0027] Figure 1 is a schematic structural diagram of the fine desulfurization unit of the blast furnace gas provided by an embodiment of the present invention;

[0028] Figure 2 is a schematic structural diagram of the fine desulfurization system of the blast furnace gas provided by an embodiment of the present invention.

[0029] Among them:

[0030] 1 - Scrubber; 2 - Heater; 3 - Hydrolysis tower; 4 - Cooler; 5 - Desulfurization tower; 6 - Heat exchanger; 7 - Demister; 8 - Pretreatment tower; 9 - Reliable cut-off device. Detailed Embodiments

[0031] To make the objectives, advantages, and features of the present utility model clearer, the following further elaborates on the present utility model in conjunction with the accompanying drawings and specific embodiments. It should be noted that the accompanying drawings are in a very simplified form and use non-precise scales, solely for the purpose of facilitating and clearly assisting in explaining the objectives of the embodiments of the present utility model. To make the objectives, features, and advantages of the present utility model more obvious and understandable, please refer to the accompanying drawings. It should be noted that the structures, scales, sizes, etc. shown in the drawings of this specification are only used to cooperate with the content disclosed in the specification for those familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present utility model. Any modification of the structure, change in the proportional relationship, or adjustment of the size, in the case of being the same or similar to the effects that the present utility model can produce and the objectives that can be achieved, should still fall within the scope covered by the technical content disclosed by the present utility model.

[0032] As used in the present utility model, the singular forms "a", "an", and "the" include plural objects unless the context clearly indicates otherwise. As used in the present utility model, the term "or" is generally used in the sense of including "and / or" unless the context clearly indicates otherwise. As used in the present utility model, the term "several" is generally used in the sense of including "at least one" unless the context clearly indicates otherwise. As used in the present utility model, the term "at least two" is generally used in the sense of including "two or more" unless the context clearly indicates otherwise. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first", "second", "third" may explicitly or implicitly include one or at least two of such features.

[0033] In the description of the present utility model, unless otherwise clearly specified and defined, the terms "installed", "connected", "coupled", "fixed" shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the connection inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0034] Please refer to Figure 1 , this embodiment provides a fine desulfurization unit for blast furnace gas, including a scrubbing tower 1, a heater 2, a hydrolysis tower 3, a cooler 4, and a desulfurization tower 5 connected in sequence, where:

[0035] The scrubbing tower 1 is used to wash the blast furnace gas to remove acidic gases in the blast furnace gas;

[0036] Heater 2, used for heating the washed blast furnace gas;

[0037] A hydrolysis tower 3, used for hydrolyzing the heated blast furnace gas to convert organic sulfur in the blast furnace gas into hydrogen sulfide;

[0038] Cooler 4, used to cool down the blast furnace gas after hydrolysis treatment;

[0039] The desulfurization tower 5 is used to remove hydrogen sulfide from the cooled blast furnace gas.

[0040] After being treated by the scrubber 1, most of the acidic components in the blast furnace gas can be removed. Then, the blast furnace gas is heated by the heater 2 and enters the hydrolysis tower 3 to improve the efficiency of converting organic sulfur into hydrogen sulfide. Then, the blast furnace gas is cooled by the cooler 4 and enters the desulfurization tower 5 to efficiently remove most of the hydrogen sulfide in the blast furnace gas, thereby realizing the fine desulfurization of the blast furnace gas.

[0041] In this embodiment, the washing tower 1 uses water or alkali solution for spray washing, which can remove acidic gases such as fluoride and chlorine in the blast furnace gas, thereby reducing the acidic gases in the blast furnace gas as much as possible, which can prevent the halogen components from interfering with or even poisoning the subsequent hydrolysis, desulfurization and other treatment processes, and can also reduce the corrosion of the halogen components to the gas pipeline and equipment. It should be understood that if water is used for spray washing, most of the acidic gases can be dissolved in water to achieve removal, and if alkali solution is used for spray washing, the fluoride, chlorine and other acidic gases in the blast furnace gas are removed by chemical reaction.

[0042] Preferably, the blast furnace gas fine desulfurization unit also includes a heat exchanger 6, the two ends of the heating side of the heat exchanger 6 are respectively connected to the washing tower 1 and the heater 2, and the two ends of the cooling side of the heat exchanger 6 are respectively connected to the hydrolysis tower 3 and the cooler 4. Since the subsequent pretreatment and hydrolysis of coal gas require a higher temperature (80-100°C), and the desulfurization of coal gas requires a lower temperature (35-50°C), the heat exchanger 6 is provided to adjust the temperature of the coal gas and reduce the energy consumption of heating the coal gas. Specifically, the heat exchanger 6 provided in this embodiment can achieve a one-time heating of the low-temperature coal gas and a one-time cooling of the high-temperature coal gas after hydrolysis by exchanging heat with the low-temperature coal gas before entering the heater 2, that is, through the heat exchange between the high-temperature coal gas and the low-temperature coal gas, it is ensured that the heat energy is circulated in the system, thereby reducing the energy consumption of the system.

[0043] In this embodiment, the heat exchanger 6 includes but is not limited to a plate type or a shell and tube type, and its heat exchange elements are made of non-metallic or stainless steel or other materials with strong corrosion resistance to ensure the durability of the equipment.

[0044] In this embodiment, by setting up the heater 2, the blast furnace gas can be reheated for the subsequent gas pretreatment and hydrolysis, providing a relatively high gas temperature to ensure the effectiveness of the system. The heater 2 includes, but is not limited to, a steam heater 2 or an electric heater 2. The steam can be saturated steam or superheated steam. By adjusting the amount of the heating medium, the temperature of the blast furnace gas entering the pretreatment tower 8 and the hydrolysis tower 3 after passing through the heater 2 can be regulated to adapt to the changes in the performance of the pretreatment agent and the hydrolysis catalyst and the reaction temperature. In this embodiment, the heating element of the heater 2 needs to consider the corrosiveness and pressure resistance of the gas. After passing through the heater 2, the gas temperature is between 80 - 100 °C.

[0045] Preferably, the fine desulfurization unit of the blast furnace gas further includes a demister 7 disposed between the scrubbing tower 1 and the heat exchanger 6. The demister 7 is used to remove the liquid water in the scrubbed blast furnace gas. The blast furnace gas after alkali washing is usually in a saturated state at 30 - 40 °C and contains a large amount of liquid water. Although part of the liquid water is removed by the demisting layer at the outlet of the scrubbing tower 1, limited by the effect of the demisting layer, the flow field uniformity, and the temperature drop of the pipeline system, a separate demister 7 can be set up before entering the next process to effectively remove the liquid water in the blast furnace gas, which can not only reduce the corrosiveness of the acidic gas dissolved in water to the system but also reduce the energy consumption of the subsequent gas heating.

[0046] Preferably, the fine desulfurization unit of the blast furnace gas further includes a pretreatment tower 8 disposed between the heater 2 and the hydrolysis tower 3. The pretreatment tower 8 is used to remove the halogen components in the blast furnace gas. It should be noted that alkali washing can remove some acidic components such as fluorine and chlorine in the blast furnace gas, but due to the presence of liquid water, there are still a certain amount of halogen components such as fluorine and chlorine in the gas. These halogen components have a strong poisoning effect on the hydrolysis catalyst and the desulfurization catalyst. Therefore, in this embodiment, by setting up the pretreatment tower 8, a pretreatment agent containing alkaline substances such as calcium or sodium is used to further remove the halogen components such as fluorine and chlorine in the blast furnace gas, providing a relatively clean raw material gas for hydrolysis and desulfurization.

[0047] In this embodiment, the pretreatment tower 8 can be an axial tower or a radial tower, and the pretreatment agent can be solid particles in spherical, columnar or irregular shapes.

[0048] In this embodiment, the relatively clean blast furnace gas after pretreatment enters the hydrolysis tower 3. Under the catalytic action of the hydrolysis catalyst at a temperature of 80 - 100 °C, the organic sulfur in the blast furnace gas such as carbonyl sulfide is converted into hydrogen sulfide that is easy to remove. The chemical reaction formula of carbonyl sulfide is:

[0049] COS + H2O = H2S + CO2

[0050] In this embodiment, the hydrolysis tower 3 can be an axial tower or a radial tower, and the hydrolysis catalyst and the desulfurization catalyst can be solid particles in spherical, columnar or irregular shapes.

[0051] In this embodiment, after the hydrolyzed blast furnace gas is cooled once by the heat exchanger 6, the temperature is still relatively high, which is not conducive to the removal effect of the desulfurization catalyst. Therefore, in the present utility model, by setting the cooler 4 for secondary temperature reduction, a lower desulfurization temperature required by the desulfurization tower 5 can be provided.

[0052] In this embodiment, the cooler 4 adopts a tubular or plate heat exchanger, and the cooling medium can adopt circulating cooling water or other cooling media. By adjusting the amount of the cooling medium, the temperature of the blast furnace gas entering the desulfurization tower 5 after cooling is adjusted to adapt to the performance of the desulfurization catalyst and the change of the reaction temperature. At the same time, the heat exchange elements of the cooler 4 need to have high corrosion resistance and pressure resistance, and non-metallic materials or stainless steel materials such as stainless steel can be used.

[0053] It should be noted that the heat exchanger 6 is a preferred solution in this embodiment. If the heat exchanger 6 is not provided, the blast furnace gas can also be heated to the temperature required for hydrolysis or cooled to the temperature required for desulfurization by adjusting the amount of the heating medium in the heater 2 and the amount of the cooling medium in the cooler 4. The present utility model does not limit this.

[0054] The relatively clean blast furnace gas after being cooled by the cooler 4 finally enters the desulfurization tower 5. Under the temperature of 35 - 50 °C and the action of the desulfurization catalyst, hydrogen sulfide and a small amount of acidic gases are absorbed and removed, and finally the removal of organic sulfur and hydrogen sulfide in the fine desulfurization of blast furnace gas is realized, and the removal efficiency of both is not less than 90%.

[0055] In this embodiment, the desulfurization tower 5 can be an axial tower or a radial tower, and the desulfurization catalyst can be spherical, columnar or irregularly shaped solid particles.

[0056] Based on the same technical concept, as Figure 2 shown, the embodiment of the present utility model also provides a fine desulfurization system for blast furnace gas, which includes at least two parallelly arranged fine desulfurization units for blast furnace gas as described above, and the appropriate number of fine desulfurization units for blast furnace gas can be set according to the size of the gas volume. Generally speaking, the fine desulfurization units for blast furnace gas should be at least one more than the fine desulfurization units for blast furnace gas required for processing the gas volume, as a spare unit for maintenance.

[0057] In this embodiment, the fine desulfurization unit for blast furnace gas further includes a demister 7 arranged between the scrubbing tower 1 and the heat exchanger 6, and all the fine desulfurization units for blast furnace gas share one scrubbing tower 1 and one demister 7.

[0058] Preferably, reliable cut-off devices 9 are respectively arranged between the demister 7 and the heat exchanger 6 of each fine desulfurization unit of blast furnace gas, and at the outlets of each desulfurization tower 5. When replacing agents or overhauling equipment, by cutting off the reliable cut-off device 9 of the corresponding fine desulfurization unit of blast furnace gas, the overhaul or material replacement of this fine desulfurization unit of blast furnace gas can be carried out without affecting the function of other fine desulfurization units of blast furnace gas in treating all blast furnace gas.

[0059] In summary, the embodiment of the present invention provides a fine desulfurization unit of blast furnace gas and its system. After the blast furnace gas is treated by the scrubbing tower 1, most of the acidic components in the blast furnace gas are removed. After most of the liquid water is removed by the demister 7, it enters the heat exchanger 6 for preheating, and then enters the heater 2 for heating. The heated blast furnace gas enters the pretreatment tower 8, and after further removing halogen components such as fluorine and chlorine, it enters the hydrolysis tower 3 to convert the organic sulfur in the blast furnace gas into hydrogen sulfide. The hydrolyzed blast furnace gas is first cooled by the heat exchanger 6 and then cooled by the cooler 4 and then enters the desulfurization tower 5 to efficiently remove most of the hydrogen sulfide in the blast furnace gas, thus realizing the fine desulfurization of the blast furnace gas.

[0060] In addition, it should also be recognized that although the present invention has been disclosed above with preferred embodiments, the above embodiments are not intended to limit the present invention. For any person skilled in the art, without departing from the scope of the technical solution of the present invention, many possible changes and modifications can be made to the technical solution of the present invention by using the disclosed technical content above, or it can be modified into equivalent embodiments with equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still belong to the scope protected by the technical solution of the present invention.

Claims

1. A blast furnace gas fine desulfurization unit, characterized in that: It includes a washing tower, a heater, a hydrolysis tower, a cooler and a desulfurization tower connected in sequence, wherein: The washing tower is used to wash the blast furnace gas to remove the acid gas in the blast furnace gas; The heater is used to heat the washed blast furnace gas; The hydrolysis tower is used to hydrolyze the heated blast furnace gas to convert the organic sulfur in the blast furnace gas into hydrogen sulfide; The cooler is used to cool the blast furnace gas after the hydrolysis treatment; The desulfurization tower is used to remove hydrogen sulfide from the cooled blast furnace gas.

2. The blast furnace gas fine desulfurization unit according to claim 1, characterized in that: The washing tower uses water or alkaline solution to wash the blast furnace gas.

3. The blast furnace gas fine desulfurization unit according to claim 1, characterized in that: The blast furnace gas fine desulfurization unit also includes a heat exchanger, and the two ends of the heating side of the heat exchanger are respectively connected to the washing tower and the heater, and the two ends of the cooling side of the heat exchanger are respectively connected to the hydrolysis tower and the cooler.

4. The blast furnace gas fine desulfurization unit according to claim 3, characterized in that: The heat exchange element of the heat exchanger and the heating element of the heater are both made of corrosion-resistant materials.

5. The blast furnace gas fine desulfurization unit according to claim 3, characterized in that: The blast furnace gas fine desulfurization unit further includes a demister arranged between the washing tower and the heat exchanger, and the demister is used to remove liquid water in the washed blast furnace gas.

6. The blast furnace gas fine desulfurization unit according to claim 1, characterized in that: The blast furnace gas fine desulfurization unit further comprises a pretreatment tower disposed between the heater and the hydrolysis tower, and the pretreatment tower is used to remove halogen components in the blast furnace gas.

7. The blast furnace gas fine desulfurization unit according to claim 1, characterized in that: The temperature of the blast furnace gas entering the hydrolysis tower is between 80°C and 100°C.

8. The blast furnace gas fine desulfurization unit according to claim 1, characterized in that: The temperature of the blast furnace gas entering the desulfurization tower is between 35°C and 50°C.

9. A blast furnace gas fine desulfurization system, characterized in that: It comprises at least two blast furnace gas fine desulfurization units according to any one of claims 1-8 which are arranged in parallel.

10. A blast furnace gas fine desulfurization system, characterized in that: The blast furnace gas fine desulfurization unit also includes a demister arranged between the washing tower and the heat exchanger, and all the blast furnace gas fine desulfurization units share one washing tower and the demister.

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