Flue gas treatment system

Abstract

The utility model discloses a flue gas treatment system. The system comprises a first flue gas treatment unit used for first flue gas dry desulfurization and a second flue gas treatment unit used for second flue gas semi-dry or wet desulfurization, the first flue gas treatment unit comprises a first desulfurization mechanism and a first dust remover, and a flue gas inlet of the first dust remover is connected with a flue gas outlet of the first desulfurization mechanism; the second flue gas treatment unit comprises a second desulfurization mechanism, and a desulfurized fly ash outlet of the first dust remover is connected with a desulfurizer supply unit of the second desulfurization mechanism through a desulfurized fly ash conveying unit. According to the utility model, the flue gas can be respectively subjected to dry desulfurization and semi-dry desulfurization, the by-product of dry desulfurization is reused in the second desulfurization mechanism, the problem of treatment of the by-product of dry desulfurization is solved, the solid waste emission is reduced, meanwhile, the by-product of dry desulfurization can be used as a desulfurizer of semi-dry desulfurization, the investment cost of the second flue gas treatment unit is reduced, and the economic benefit is increased. The economic benefit is improved.

Description

Technical Field

[0001] The utility model relates to the field of flue gas treatment, in particular to a flue gas treatment system. Background Art

[0002] Flue gas desulfurization is divided into three categories: wet method, semi-dry method, and dry method. Among them, the applicable desulfurization methods for coke oven flue gas are sodium-based dry method (SDS), calcium-based granular dry method (DDSN), calcium-based powder dry method (ACA), activated coke dry method, and calcium-based semi-dry method (CFB); the applicable desulfurization methods for coke dry quenching are sodium-based dry method (SDS), calcium-based powder dry method (ACA), and activated coke dry method; the applicable desulfurization methods for ground stations are sodium-based dry method (SDS), calcium-based powder dry method (ACA), and activated coke dry method. Dry desulfurization is widely used because of its simple process, low energy consumption, no wastewater generation, and high temperature after purification, which is beneficial to emission.

[0003] However, the desulfurization efficiency of the current dry desulfurization process is not high, so the utilization rate of desulfurizer is also not high. There are still a large number of unutilized effective components (such as sodium hydroxide, calcium hydroxide, or sodium carbonate) in the desulfurization by-products (desulfurization ash). The by-products generated by dry desulfurization are usually transported to landfills for treatment, resulting in great waste. Therefore, it is particularly important to recycle the by-products of dry desulfurization. Summary of the Utility Model

[0004] In order to solve the above problems, the utility model provides a flue gas treatment system, which includes a first flue gas treatment unit for dry desulfurization of the first flue gas and a second flue gas treatment unit for semi-dry or wet desulfurization of the second flue gas. The first flue gas treatment unit includes a first desulfurization mechanism and a first dust collector. The flue gas inlet of the first dust collector is connected to the flue gas outlet of the first desulfurization mechanism; the second flue gas treatment unit includes a second desulfurization mechanism. The desulfurization ash outlet of the first dust collector is connected to the desulfurizer supply unit of the second desulfurization mechanism through a desulfurization ash conveying unit.

[0005] Further, the desulfurizer supply unit includes a second desulfurizer bin. The desulfurization ash conveying unit is connected to the second desulfurizer bin, and the second desulfurizer bin is connected to the second desulfurization mechanism through a desulfurizer supply pipeline.

[0006] Further, a fresh desulfurizer pipeline for supplying fresh desulfurizer is also connected to the second desulfurizer bin.

[0007] Further, a mixing component for mixing fresh desulfurizer and desulfurization ash is also provided in the second desulfurizer bin.

[0008] Further, flow regulating valves are respectively provided on the desulfurization ash outlet of the first dust collector, the fresh desulfurizer pipeline, and the desulfurizer supply pipeline.

[0009] Further, flue gas composition detection devices are respectively provided at the flue gas inlet and the flue gas outlet of the second desulfurization mechanism, and signal interlocks are respectively established between each of the flue gas composition detection devices and each flow regulating valve.

[0010] Further, the second flue gas treatment unit further includes an SCR denitration reactor and a second chimney. The flue gas inlet of the SCR denitration reactor is connected to the flue gas outlet of the second dust collector, and the second chimney is connected to the flue gas outlet of the SCR denitration reactor.

[0011] Further, a circulating flue is connected in parallel to the pipeline between the SCR denitration reactor and the second chimney, and the circulating flue is connected to the flue gas inlet of the second desulfurization mechanism.

[0012] Further, heat exchangers are respectively connected to the flue gas inlet and the flue gas outlet of the SCR denitration reactor.

[0013] Further, the first flue gas treatment unit further includes a first desulfurizing agent bin. The first desulfurizing agent bin is connected to the first desulfurization mechanism through a desulfurizing agent conveying unit. The desulfurizing agent conveying unit includes a screw feeder, a Roots blower and an ejector. The screw feeder is arranged at the discharge end of the first desulfurizing agent bin. The Roots blower is connected to the discharge port of the screw feeder. The ejector is arranged at the desulfurizing agent inlet of the first desulfurization mechanism and is connected to the Roots blower.

[0014] Due to the adoption of the above technical solutions, the present utility model has the following beneficial effects compared with the prior art:

[0015] 1) The flue gas treatment system provided by the present utility model can respectively perform dry desulfurization on the first flue gas and semi-dry or wet desulfurization on the second flue gas, and recycle the by-products of dry desulfurization to the second desulfurization mechanism, solving the problem of treating the by-products after dry desulfurization and reducing solid waste emissions. At the same time, the by-products of dry desulfurization can be used as desulfurizing agents for semi-dry or wet desulfurization, reducing the investment cost of the second flue gas treatment unit and improving economic benefits.

[0016] 2) In the dry desulfurization by-product recycling system provided by the present utility model, a mixing component for mixing fresh desulfurizing agent and desulfurization ash is provided in the second desulfurizing agent bin, which can fully mix the fresh desulfurizing agent with the waste desulfurizing agent in the desulfurization ash and enter the second desulfurization mechanism for flue gas desulfurization. While ensuring the flue gas desulfurization effect, the amount of fresh desulfurizing agent used can be saved, thereby saving costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0018] Figure 1 Structural schematic diagram of the flue gas treatment system provided by the present invention;

[0019] Figure 2 Structural schematic diagram of the first flue gas treatment unit in the flue gas treatment system provided by the present invention.

[0020] 1 - First flue gas; 2 - Second flue gas; 3 - First desulfurizing agent bin; 4 - Desulfurizing agent conveying unit; 41 - Screw feeder; 42 - Roots blower; 43 - Butterfly valve; 44 - Injector; 5 - First desulfurization mechanism; 6 - First dust collector; 7 - First induced draft fan; 8 - First chimney; 9 - Desulfurized ash conveying unit; 10 - Second desulfurizing agent bin; 11 - Second desulfurization mechanism; 12 - Second dust collector; 13 - SCR denitration reactor; 14 - Heat exchanger; 15 - Second induced draft fan; 16 - Second chimney; 17 - Circulation flue; 18 - Desulfurizing agent supply pipeline; 19 - Fresh desulfurizing agent pipeline. Detailed implementation manners

[0021] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention. In the drawings, for clarity, the size and relative size of some parts may be enlarged.

[0022] In the description of the present invention, unless otherwise clearly defined and limited, the terms "connection" and "connection" shall be interpreted in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. It can be the communication 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 invention can be understood according to specific situations.

[0023] In the description of the present utility model, the orientation or positional relationships such as "upper", "lower", "left", "right", "front", "rear", "center", "horizontal", "vertical", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings. These are only for the convenience of description and simplifying the operation, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present utility model.

[0024] In addition, in the description of the present utility model, the terms "first" and "second" are only used for distinction in description, and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. In addition, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features.

[0025] As shown in the attached Figure 1 description of the specification, the present utility model provides a flue gas treatment system, which includes a first flue gas treatment unit for dry desulfurization of the first flue gas 1 and a second flue gas treatment unit for semi-dry or wet desulfurization of the second flue gas 2. The first flue gas treatment unit includes a first desulfurization mechanism 5 and a first dust collector 6, and the flue gas inlet of the first dust collector 6 is connected to the flue gas outlet of the first desulfurization mechanism 5; the second flue gas treatment unit includes a second desulfurization mechanism 11, and the desulfurized ash outlet of the first dust collector 6 is connected to the desulfurizing agent supply unit of the second desulfurization mechanism 11 through a desulfurized ash conveying unit 9.

[0026] Specifically, in this embodiment, the second desulfurization mechanism 11 is semi-dry desulfurization, the first desulfurization mechanism 5 is a dry desulfurization component for dry desulfurization of the first flue gas 1, and the second desulfurization mechanism 11 is a semi-dry desulfurization component for dry desulfurization of the second flue gas 2. Among them, dry desulfurization can adopt sodium-based dry desulfurization, calcium-based powder dry desulfurization, calcium-based granular dry desulfurization, etc., and semi-dry desulfurization can adopt sodium-based semi-dry desulfurization, calcium-based semi-dry desulfurization, etc. In this embodiment, taking the flue gas treatment in the iron and steel coking industry as an example, the first desulfurization mechanism 5 is preferably a calcium-based powder dry desulfurization component, and the second desulfurization mechanism 11 is preferably a calcium-based semi-dry desulfurization component. After the first flue gas 1 is desulfurized by the first desulfurization mechanism 5, it enters the first dust collector 6 to remove particulate matter in the flue gas. The desulfurizing agent carried in the flue gas is deposited in the first dust collector 6 to obtain desulfurized ash. The desulfurized ash is transported to the desulfurizing agent supply unit of the second desulfurization mechanism 11 through the desulfurized ash conveying unit 9. The unreacted desulfurizing agent in the desulfurized ash can be used to continue flue gas desulfurization, which can effectively save the amount of desulfurizing agent in semi-dry desulfurization and save costs.

[0027] Preferably, both the first flue gas 1 and the second flue gas 2 enter their respective corresponding flue gas treatment units for flue gas treatment after heat recovery from the waste heat boiler.

[0028] Optimized implementation mode. The desulfurizer supply unit includes a second desulfurizer bin 10, which is used to store the desulfurizer required for semi-dry desulfurization. The desulfurizer includes fresh desulfurizer and desulfurization ash recovered from dry desulfurization. The desulfurization ash conveying unit 9 is connected to the second desulfurizer bin 10. The second desulfurizer bin 10 is connected to the second desulfurization mechanism 11 through a desulfurizer supply pipeline 18 to convey the desulfurizer in the second desulfurizer bin 10 into the second desulfurization mechanism 11 for the desulfurization reaction of the second flue gas 2.

[0029] Optimized implementation mode. A fresh desulfurizer pipeline 19 for supplying fresh desulfurizer is further connected to the second desulfurizer bin 10.

[0030] In this embodiment, to improve the semi-dry desulfurization efficiency, the desulfurization ash and fresh desulfurizer are mixed in the second desulfurizer bin 10. The desulfurization ash conveying unit 9 includes a desulfurization ash conveying pipeline. One end of the desulfurization ash conveying pipeline is connected to the desulfurization ash outlet of the first dust collector 6, and the other end is connected to the second desulfurizer bin 10, so that the desulfurization ash recovered from the first dust collector 6 can be conveyed into the second desulfurizer bin 10 and mixed with the fresh desulfurizer. The discharge port of the second desulfurizer bin 10 is connected to the second desulfurization mechanism 11 through a desulfurizer supply pipeline 18. The end of the desulfurizer supply pipeline 18 is connected with a spraying unit, which can spray the desulfurizer into the flue gas, so that the desulfurizer is fully and evenly dispersed in the flue gas, improving the flue gas desulfurization efficiency.

[0031] The second desulfurization mechanism 11 is preferably a CFB desulfurization tower. The spraying unit is arranged inside the tower and above the flue gas inlet. A spraying mechanism is further provided on the CFB desulfurization tower. The second flue gas 2 enters the tower from the bottom of the CFB desulfurization tower and is mixed with the desulfurizer sprayed into the tower. The second flue gas 2 contacts the sprayed water of the spraying mechanism in a countercurrent manner to complete the semi-dry desulfurization operation. The fresh desulfurizer in the second desulfurizer bin 10 is preferably slaked lime.

[0032] In this embodiment, the desulfurizer used in dry desulfurization is a calcium-based powdered desulfurizer. A coating film will form on the outer surface of the desulfurized desulfurizer after the reaction, and the unreacted desulfurizer is coated inside the coating film, which affects the reaction efficiency. To improve the reaction efficiency of the waste desulfurizer in the desulfurization ash, a mixing component for mixing fresh desulfurizer and desulfurization ash is further provided in the second desulfurizer bin 10. The mixing component includes a grinder, which is located at the feeding end of the second desulfurizer bin 10 and can grind the desulfurization ash, crush the agglomerated desulfurization ash, and obtain powdered desulfurizer with a smaller particle size. This can improve the mixing uniformity of the desulfurizer and the flue gas, and also break the coating film on the outer surface of the desulfurized desulfurizer after the reaction. At the same time, it can also make the desulfurization ash and the fresh desulfurizer mix evenly, improve the reaction efficiency of the desulfurizer and the flue gas, and thus improve the semi-dry desulfurization efficiency. Further, after the desulfurizer in the second desulfurizer bin 10 is sprayed into the second flue gas and contacts the sprayed water of the spraying mechanism, part of the remaining coating film can be dissolved by water, and the waste desulfurizer in the desulfurization ash can continue to participate in the reaction.

[0033] In an optimized implementation manner, flow regulating valves 20 are respectively provided on the desulfurization ash outlet of the first dust collector 6, the fresh desulfurizer pipeline 19, and the desulfurizer supply pipeline 18. The flow regulating valves 20 can adjust the amounts of the fresh desulfurizer and the desulfurization ash entering the second desulfurizer bin 10, and can adjust the ratio of the fresh desulfurizer to the desulfurization ash according to the flow rate of the second flue gas 2 and the sulfur content therein to ensure the desulfurization effect of the second flue gas 2.

[0034] In an optimized implementation manner, flue gas composition detection devices are respectively provided at the flue gas inlet and the flue gas outlet of the second desulfurization mechanism 11, and signal interlocks are established between each of the flue gas composition detection devices and each of the flow regulating valves 20. The flue gas composition at the flue gas outlet is monitored in real time. When the monitored sulfur content of the flue gas composition is less than the set value, it means that the desulfurization effect of the second desulfurization mechanism 11 is good, and the amount of the fresh desulfurizer can be appropriately reduced according to the actual value to save the use of the fresh desulfurizer while ensuring the desulfurization effect of the second flue gas 2. When the monitored sulfur content of the flue gas composition is greater than the set value, the amount of the fresh desulfurizer can be increased through the corresponding flow regulating valve to ensure the desulfurization effect of the second flue gas 2. Of course, when the monitored sulfur content of the flue gas composition is greater than the set value as described above, the flue gas also meets the emission standards.

[0035] Optimized implementation mode, the second flue gas treatment unit further includes an SCR denitration reactor 13 and a second chimney 16. The flue gas inlet of the SCR denitration reactor 13 is connected to the flue gas outlet of the second dust collector 12. After the second flue gas 2 is desulfurized by the second desulfurization mechanism 11, it enters the second dust collector 12 for dust removal. The second flue gas 2 after dust removal enters the SCR denitration reactor 13 for denitration reaction. The second chimney 16 is connected to the flue gas outlet of the SCR denitration reactor 13. After the purified flue gas is detected to be qualified, it is discharged from the second chimney 16.

[0036] Preferably, to ensure the smooth progress of the denitration reaction in the SCR denitration reactor 13, heat exchangers 14 are respectively connected to the flue gas inlet and the flue gas outlet of the SCR denitration reactor 13. The heat exchanger 14 is preferably a GGH heat exchanger. Specifically, a GGH heat exchanger is provided at the flue gas inlet of the SCR denitration reactor 13, which can heat the second flue gas 2 entering the SCR denitration reactor 13 to make the flue gas temperature reach the set temperature of the denitration reaction. The second flue gas 2 after temperature rise enters the SCR denitration reactor 13 for denitration. The second flue gas 2 after denitration is cooled by the GGH heat exchanger at the flue gas outlet, and the waste heat of the flue gas can be recovered. The second flue gas 2 after cooling is discharged from the second chimney 16.

[0037] A second induced draft fan 15 is provided on the pipeline of the SCR denitration reactor 13 and the second chimney 16. A circulating flue 17 is connected in parallel to the outlet pipeline of the second induced draft fan 15. The circulating flue 17 is connected to the flue gas inlet of the second desulfurization mechanism 11. A flow control valve is also provided on the circulating flue 17 for adjusting the flue gas flow on the circulating flue 17. Part of the purified second flue gas 2 is introduced into the second desulfurization mechanism 11, which can adjust the flue gas inlet flow of the second desulfurization mechanism 11 to ensure the normal operation of the CFB desulfurization tower and the SCR denitration reactor 13. The amount of the circulating flue gas can be adjusted according to the amount of the incoming second flue gas.

[0038] Optimized implementation mode, the first desulfurization mechanism 5 includes a desulfurization flue. One end of the desulfurization flue is provided with a flue gas inlet for the first flue gas 1 to enter. The flue gas flows in the desulfurization flue towards the flue gas outlet direction and is mixed with the desulfurizing agent sprayed into the desulfurization flue for desulfurization reaction. The other end of the desulfurization flue is connected to the first dust collector 6. The first flue gas 1 after being desulfurized by the desulfurization flue enters the first dust collector 6 for flue gas dust removal. The collected desulfurized ash is recycled to the second flue gas treatment unit.

[0039] Preferably, the first dust collector 6 is preferably a bag filter, an electrostatic precipitator or a cyclone dust collector. In this embodiment, the first dust collector 6 is a bag filter; the second dust collector 12 is preferably a bag filter, an electrostatic precipitator or a cyclone dust collector. In this embodiment, the second dust collector 12 is a bag filter.

[0040] Optimized implementation modes, as shown in the attached drawings of the specification Figure 2 As shown, the first flue gas treatment unit further includes a first desulfurizer bin 3, the first desulfurizer bin 3 is connected to the desulfurization flue through a desulfurizer conveying unit 4, the desulfurizer conveying unit 4 includes a screw feeder 41, a Roots blower 42 and an injector 44, the screw feeder 41 is arranged at the discharge end of the first desulfurizer bin 3, the Roots blower 42 is connected to the discharge port of the screw feeder 41, the injector 44 is arranged at the desulfurizer inlet of the desulfurization flue and is connected to the Roots blower 41, and a butterfly valve 43 is further arranged on the pipelines of the Roots blower 42 and the injector 11 for regulating the flow rate.

[0041] In this embodiment, the first desulfurizer bin 3 is provided with two discharge ports, two screw feeders 41 and Roots blowers 42 are provided, one is for standby. The screw feeder 41 quantitatively feeds a highly active calcium-based powdered desulfurizer with a particle size of 325 mesh and a sieving rate > 85% into the Roots blower 42. A butterfly valve 43 and an injector 44 are arranged on the outlet pipeline of the Roots blower 42. The butterfly valve 43 can regulate the desulfurizer flow rate, and the calcium-based powdered desulfurizer is sprayed into the desulfurization flue through the injector 44.

[0042] Optimized implementation mode, the discharge port of the second desulfurizer bin 10 can convey the desulfurizer to the CFB desulfurization tower through the above-mentioned desulfurizer conveying unit.

[0043] Optimized implementation mode, the first flue gas treatment unit further includes a first chimney 8, the first chimney 8 is connected to the flue gas outlet of the first dust collector 6, and a first induced draft fan 7 is arranged on the pipeline between the first dust collector 6 and the first chimney 8. After the first flue gas 1 is desulfurized, it is dust-removed and purified in the first dust collector 6 and then discharged into the air through the first chimney 8 after reaching the standard.

[0044] Meanwhile, the content not described in detail in this specification belongs to the prior art well-known to those skilled in the art.

[0045] Those skilled in the art of this technology should understand that the present utility model can be implemented in many other specific forms without departing from the spirit and scope of the present utility model. Although the embodiments of the present utility model have been described, it should be understood that the present utility model should not be limited to these embodiments, and those skilled in the art of this technology can make changes and modifications within the spirit and scope of the present utility model defined by the appended claims.

Claims

1. A flue gas treatment system, characterized in that, It includes a first flue gas treatment unit for the dry desulfurization of the first flue gas and a second flue gas treatment unit for the semi-dry or wet desulfurization of the second flue gas. The first flue gas treatment unit includes a first desulfurization mechanism and a first dust collector, and the flue gas inlet of the first dust collector is connected to the flue gas outlet of the first desulfurization mechanism; the second flue gas treatment unit includes a second desulfurization mechanism, and the desulfurized ash outlet of the first dust collector is connected to the desulfurizer supply unit of the second desulfurization mechanism through a desulfurized ash conveying unit.

2. The flue gas treatment system according to claim 1, wherein The desulfurizer supply unit includes a second desulfurizer bin, the desulfurized ash conveying unit is connected to the second desulfurizer bin, and the second desulfurizer bin is connected to the second desulfurization mechanism through a desulfurizer supply pipeline.

3. The flue gas treatment system according to claim 2, wherein A fresh desulfurizer pipeline for supplying fresh desulfurizer is also connected to the second desulfurizer bin.

4. The flue gas treatment system according to claim 3, characterized in that, A mixing component for mixing fresh desulfurizer and desulfurized ash is also provided in the second desulfurizer bin.

5. The flue gas treatment system according to claim 3, characterized in that, Flow regulating valves are respectively provided on the desulfurized ash outlet of the first dust collector, the fresh desulfurizer pipeline, and the desulfurizer supply pipeline.

6. The flue gas treatment system according to claim 5, characterized in that, Flue gas composition detection devices are respectively provided at the flue gas inlet and the flue gas outlet of the second desulfurization mechanism, and signal interlocks are established between each of the flue gas composition detection devices and each flow regulating valve.

7. The flue gas treatment system according to claim 1, wherein The second flue gas treatment unit further includes a second dust collector, an SCR denitration reactor, and a second chimney. The second dust collector is connected to the second desulfurization mechanism, the flue gas inlet of the SCR denitration reactor is connected to the flue gas outlet of the second dust collector, and the second chimney is connected to the flue gas outlet of the SCR denitration reactor.

8. The flue gas treatment system according to claim 7, wherein A circulation flue is connected in parallel to the pipeline between the SCR denitration reactor and the second chimney, and the circulation flue is connected to the flue gas inlet of the second desulfurization mechanism.

9. The flue gas treatment system according to claim 7, wherein Heat exchangers are respectively connected to the flue gas inlet and the flue gas outlet of the SCR denitration reactor.

10. The flue gas treatment system according to claim 1, characterized in that, The first flue gas treatment unit further includes a first desulfurizer bin, the first desulfurizer bin is connected to the first desulfurization mechanism through a desulfurizer conveying unit, the desulfurizer conveying unit includes a screw feeder, a Roots blower, and an ejector. The screw feeder is arranged at the discharge end of the first desulfurizer bin, the Roots blower is connected to the discharge port of the screw feeder, and the ejector is arranged at the desulfurizer inlet of the first desulfurization mechanism and is connected to the Roots blower.

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