Exhaust gas desulfurization agent

Abstract

To provide a desulfurization agent that does not generate CO or CO2 during its production and has sufficient adsorption performance as a filler used in desulfurization equipment.SOLUTION: An exhaust gas desulfurization agent of the present invention is a desulfurization agent that is filled in an adsorption tower 4 in an exhaust gas treatment system for desulfurization comprising an adsorption tower 4 and a regeneration tower 5. The desulfurization agent consists of gas-activated carbon and non-gas-activated carbon which includes ironmaking coke, and the ratio of non-gas-activated carbon to the gas-activated carbon in the desulfurization agent is from 10% to 90%. Preferably, the specific surface area of the non-gas-activated carbon is 15 m2 / g or more, and the particle sizes of the non-gas activated carbon and the gas activated carbon satisfy the condition where the particle size D1 (mm) of the non-gas activated carbon / the particle size D2 (mm) of the gas-activated carbon is ≤0.8.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a flue gas desulfurization agent packed in an adsorption tower in an flue gas treatment facility equipped with an adsorption tower and a regeneration tower. [Background technology]

[0002] The desulfurization agent filled in the desulfurization equipment is generally activated carbon that has undergone gas activation treatment to achieve high adsorption performance. For example, Patent Document 1 discloses a technology for producing activated carbon with high adsorption performance through gas activation treatment (hereinafter referred to as gas-activated carbon). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-213544 Summary of the Invention [Problem to be solved by the invention]

[0004] In the technology disclosed in Patent Document 1, gas activation treatment requires the reaction of a carbon material with a gas such as water vapor at high temperatures to form pores in the activated carbon, which poses the problem of generating CO and CO2. In recent years, from the perspective of environmental friendliness, there has been a strong need to reduce CO2 emissions during the production of various materials, and the desulfurization agents used in desulfurization equipment are no exception. On the other hand, activated carbon that has not undergone gas activation treatment (hereinafter referred to as non-gas activated carbon) has the problem of poor adsorption performance as a filler used in desulfurization equipment.

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a desulfurization agent which does not generate CO or CO during its production and has sufficient adsorption performance as a filler for use in desulfurization equipment. [Means for solving the problem]

[0006] The flue gas desulfurization agent of the present invention is a desulfurization agent filled in an adsorption tower in a desulfurization flue gas treatment facility equipped with an adsorption tower and a regeneration tower, characterized in that the desulfurization agent is composed of gas-activated carbon and non-gas-activated carbon including steelmaking coke, and the ratio of the non-gas-activated carbon to the gas-activated carbon constituting the desulfurization agent is 10% to 90%.

[0007] In the flue gas desulfurization agent according to the present invention configured as described above, (1) The ratio of the non-gas activated carbon constituting the desulfurization agent to the gas activated carbon is 20% to 80%. (2) The specific surface area of the non-gas activated carbon is 15 m 2 / g or more, (3) The particle sizes of the non-gas-activated carbon and the gas-activated carbon are within the range of formula (1): Particle size D1 (mm) of non-gas activated carbon / Particle size D2 (mm) of gas activated carbon ≦ 0.8 ...Equation (1), This is considered to be a more preferable solution. [Effects of the Invention]

[0008] The flue gas desulfurization agent of the present invention replaces a portion of the conventional gas-activated carbon used as a filler in desulfurization equipment with non-gas-activated carbon, which has excellent CO2-saving properties, thereby improving CO2-saving properties during the production of the desulfurization agent compared to conventional methods. Furthermore, because the minimum amount of gas-activated carbon necessary is used, the flue gas can be desulfurized, reducing the amount of sulfur dioxide emitted from the chimney of the desulfurization equipment. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram for explaining an embodiment of an exhaust gas treatment facility for a sintering machine. [Figure 2] FIG. 1 is a diagram showing the appearance and various physical properties of activated coke as gas-activated carbon and coke for steelmaking that constitutes a part of non-gas-activated carbon. [Figure 3] 1 is a graph showing the relationship between the average diameter and particle size distribution of actually used coke for steelmaking and activated coke. [Figure 4] 4 is a graph showing a change in SOx concentration (ppm) before and after the adsorption tower, illustrating an example of an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] The following describes in detail the embodiments of the present invention. Note that the following embodiments are intended to exemplify devices and methods for embodying the technical concept of the present invention, and are not intended to limit the configuration to that described below. In other words, the technical concept of the present invention can be modified in various ways within the technical scope defined in the claims.

[0011] <Regarding the flue gas treatment equipment for sintering machines that uses the flue gas desulfurization agent according to the present invention> Fig. 1 is a diagram illustrating one embodiment of an exhaust gas treatment facility for a sintering machine that uses an exhaust gas desulfurization agent according to the present invention. In the example shown in Fig. 1, the exhaust gas treatment facility 1 includes an electrostatic precipitator 2, a main blower 3, an adsorption tower 4, a regeneration tower 5, a booster 6, and a chimney 7.

[0012] The electrostatic precipitator 2 collects dust and other particles in the exhaust gas generated in a sintering machine (not shown). The main blower 3 delivers the exhaust gas that has passed through the electrostatic precipitator 2 to the adsorption tower 4. The adsorption tower 4 is filled with the flue gas desulfurization agent according to the present invention, and the flue gas delivered by the main blower 3 adsorbs and removes harmful substances contained in the flue gas by the flue gas desulfurization agent, which serves as an adsorption medium. The booster 6 delivers the flue gas from which the harmful substances have been removed in the adsorption tower 4 to the chimney 7. The chimney 7 releases the flue gas from which the harmful substances have been removed, delivered from the booster 6, into the atmosphere. The regeneration tower 5 processes and regenerates the flue gas desulfurization agent from which the harmful substances have been adsorbed, and returns the regenerated flue gas desulfurization agent to the adsorption tower 4.

[0013] <About the flue gas desulfurization agent according to the present invention> The flue gas desulfurization agent of the present invention differs from commonly used activated coke (gas activated carbon) and is composed of gas activated carbon and non-gas activated carbon including steelmaking coke, with the ratio of non-gas activated carbon to gas activated carbon constituting the desulfurization agent being 10% to 90%. The flue gas desulfurization agent of the present invention is not composed solely of gas activated carbon, but is composed of a mixture of gas activated carbon and non-gas activated carbon including steelmaking coke. Therefore, compared to when only conventional gas activated carbon is used as a desulfurization agent, no CO or CO2 is generated during its production, and a desulfurization agent with sufficient adsorption performance as a filler for use in desulfurization equipment can be obtained.

[0014] In the flue gas desulfurization agent according to the present invention, the blending ratio of non-gas activated carbon to gas activated carbon is set to 10% or more and 90% or less. This is because, when the weight of non-gas activated carbon relative to the total weight of the desulfurization agent is within the above-mentioned range, the CO2 reduction and desulfurization performance required in this technical field can be achieved. The blending ratio of non-gas activated carbon to gas activated carbon is preferably 20% or more and more preferably 80% or less. If it is less than 10%, the CO2 reduction is insufficient, so it is set to 10% or more. Furthermore, if it exceeds 90%, the desulfurization performance cannot be fully exhibited as a filler for desulfurization equipment, so it is set to 90% or less.

[0015] FIG. 2 shows the appearance and various physical properties of activated coke as gas-activated carbon and steelmaking coke that constitutes part of non-gas-activated carbon. Steelmaking coke, which constitutes part of non-gas-activated carbon, has a lower SO2 adsorption capacity than activated coke, which is a commonly used gas-activated carbon. For this reason, steelmaking coke is not typically used alone. However, we discovered that by mixing it with gas-activated carbon as part of non-gas-activated carbon, it exhibits sufficient desulfurization performance as a desulfurization agent used in adsorption towers of flue gas treatment equipment, although the desulfurization performance is inferior to that of gas-activated carbon alone, and thus the present invention was achieved. For reference, FIG. 3 shows the relationship between the average diameter and particle size distribution of the steelmaking coke and activated coke actually used.

[0016] In other words, it is possible to use steelmaking coke generated in the steel industry as non-gas activated carbon. After extensive research into fillers with even greater CO2-saving properties, the inventors discovered that steelmaking coke can also be used as a desulfurization agent in desulfurization equipment. Both gas-activated and non-gas-activated carbon are typically exported from overseas, such as China, and CO2 emissions during production, as well as during sea or air transport, are problematic. On the other hand, steelmaking coke is generated within domestic steelworks, making it possible to significantly reduce CO2 emissions during transportation when imported from overseas.

[0017] Furthermore, when steelmaking coke is used, the powdering of the desulfurization agent is suppressed compared to when conventional activated coke is used. This is thought to be because, although the coke strength is at the same level, steelmaking coke has fewer pores than activated coke, which suppresses powdering.

[0018] <Preferred Examples of the Exhaust Gas Desulfurization Agent According to the Present Invention> The flue gas desulfurization agent according to the present invention has the following features (1) and (2) as preferred embodiments.

[0019] (1) The specific surface area of non-gas activated carbon is 15m 2 / g or more: Non-gas activated carbon has a specific surface area of 15m 2 / g or more. When the specific surface area is in this range, gases are more easily adsorbed, making it possible to improve desulfurization performance. As shown in Figure 2, the specific surface area of steelmaking coke alone is 15 m 2 Therefore, when forming non-gas activated carbon, it is preferable to achieve the above range of specific surface area by mixing coke for steelmaking with coke powder or the like, which has a larger specific surface area and a smaller particle size than coke for steelmaking.

[0020] (2) Particle size D1 (mm) of non-gas activated carbon / Particle size D2 (mm) of gas activated carbon ≦ 0.8: The particle size ratio of the non-gas-activated carbon to the gas-activated carbon is preferably within the above range. When the particle size ratio is within this range, the non-gas-activated carbon can penetrate into the gaps between the larger particle-sized gas-activated carbon, thereby increasing the packing density in the adsorption tower. As the packing density increases, the exhaust gas flow rate slows, allowing the gas adsorption time to be extended, resulting in improved desulfurization performance. [Example]

[0021] Example 1 Using flue gas desulfurization equipment under the same operating conditions, the desulfurization performance and CO2 reduction were compared by changing the blend ratio of non-gas activated carbon containing steelmaking coke and gas activated carbon that constitute the desulfurization agent. 2 The values of particle size (D1 / g) and particle size D1 (mm) of non-gas activated carbon / particle size D2 (mm) of gas activated carbon were calculated. For non-gas activated carbon, 10-30 mm steelmaking coke base material was used, and the under-sieved portion was sieved twice through a 15 mm square sieve. All particles were 15 mm or less, and activated coke was used as gas activated carbon. Furthermore, desulfurization performance was defined as the desulfurization rate = (inlet SOx (ppm) - outlet SOx (ppm)) / inlet SOx (ppm) in an actual plant, and was confirmed during operation. Furthermore, CO2 reduction was evaluated based on the amount of CO2 generated during production and the amount of CO2 generated during the activation process. The results are shown in Table 1 below, and the criteria for judging desulfurization performance and CO2 reduction are shown in Table 2 below.

[0022] [Table 1]

[0023] [Table 2]

[0024] From the results in Table 1, by comparing the Examples of Test Nos. 2 to 6 with the Reference Examples of Test Nos. 1 and 7, it can be seen that a flue gas desulfurization agent with good desulfurization performance and CO2 reduction can be obtained by setting the blending ratio of non-gas activated carbon to gas activated carbon at 10% to 90%. It can also be seen that a blending ratio of non-gas activated carbon to gas activated carbon of 20% to 80% is preferable.

[0025] Furthermore, by comparing Test Nos. 8 to 14 among the Examples, it was found that the specific surface area of the non-gas activated carbon was 15 m 2 / g or more. Furthermore, by comparing Test Nos. 8 to 14 among the Examples, it is clear that particle size D1 (mm) of non-gas-activated carbon / particle size D2 (mm) of gas-activated carbon is preferably 0.8 or less.

[0026] <Example 2> In addition, using the example of Test No. 4, which had a 50 / 50 blend ratio of non-gas activated carbon and gas activated carbon, as a representative example, the example of Test No. 4 and the comparative example of Test No. 1, we observed the change in SOx concentration (ppm) before and after (inlet and outlet) the adsorption tower of the flue gas treatment equipment. The results are shown in Figure 4. In Figure 4, the first half (21 / 2 / 1 to 21 / 2 / 5) shows the results when the comparative example of Test No. 1 was used as the desulfurization agent, while the second half (21 / 2 / 6 to 21 / 2 / 9) shows the results when the example of Test No. 4 was used as the desulfurization agent. The results in Figure 4 indicate that both samples were able to maintain low outlet SOx relative to inlet SOx over a long period of time, maintaining the required desulfurization performance. From the above, it can be seen that mixing a predetermined amount of non-gas activated carbon with gas activated carbon and filling the adsorption tower can inexpensively reduce the amount of sulfur dioxide emitted from the flue gas of a sintering machine more than before while maintaining desulfurization performance. [Industrial Applicability]

[0027] In the flue gas desulfurization agent of the present invention, part of the conventional gas-activated carbon used as a filler in desulfurization equipment is replaced with non-gas-activated carbon, which has excellent CO2-saving properties, thereby improving CO2-saving properties during the production of the desulfurization agent compared to conventional methods, and is therefore industrially useful. [Explanation of symbols]

[0028] 1. Exhaust gas treatment equipment 2. Electrostatic precipitator 3 Main Blower 4 Adsorption tower 5 Regeneration Tower 6 Booster 7. Chimney

Claims

1. In a flue gas treatment facility for desulfurization, which is equipped with an adsorption tower and a regeneration tower, a desulfurization agent is filled in the adsorption tower, the desulfurization agent being characterized in that the desulfurization agent is composed of gas-activated carbon and non-gas-activated carbon including coke for steelmaking, and the ratio of the non-gas-activated carbon to the gas-activated carbon constituting the desulfurization agent is 10% to 90%.

2. 2. The flue gas desulfurization agent according to claim 1, wherein the ratio of the non-gas activated carbon constituting the desulfurization agent to the gas activated carbon is 20% to 80%.

3. The non-gas activated carbon has a specific surface area of 15 m ２ 3. The flue gas desulfurization agent according to claim 1, wherein the SiO2 content is 1 / g or more.

4. The flue gas desulfurization agent according to claim 1 or 2, characterized in that the particle sizes of the non-gas activated carbon and the gas activated carbon are within the range of formula (1): Particle diameter D1 (mm) of non-gas activated carbon / particle diameter D2 (mm) of gas activated carbon≦0.8 ...Formula (1).

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