Flue gas desulfurization and denitrification system

Abstract

The invention discloses an improved flue gas desulfurization and denitrification system. The technical problem that the denitrification efficiency is reduced due to the influence of water vapor in flue gas to be denitrified on a denitrification catalyst is solved. Comprising a catalytic flue gas desulfurization device and an SCR denitration device, the catalytic flue gas desulfurization device comprises a desulfurization reactor, the SCR denitration device comprises an SCR denitration reactor, an activated carbon-based denitration catalyst is adopted as a denitration catalyst, and the working temperature of the activated carbon-based denitration catalyst is 120-200 DEG C; a desulfurized flue gas exhaust port of the desulfurization reactor is connected with a to-be-denitrated flue gas inlet of the SCR denitration reactor through a flue gas dehumidification device, and the flue gas dehumidification device is used for reducing the content of water vapor in flue gas entering the to-be-denitrated flue gas inlet. The influence of water vapor on the activated carbon-based denitration catalyst (for example, the pore structure becomes loose) is avoided, and the sufficient contact degree of nitrogen oxide and the denitration catalyst is ensured, so that the relatively high denitration efficiency is maintained.

Description

Technical Field

[0001] The present invention relates to the technical field of industrial furnace flue gas purification, and in particular to a flue gas desulfurization and denitrification system. Background Art

[0002] The applicant provides a flue gas desulfurization and denitrification system in a Chinese patent document with publication number CN118491291A (see paragraph 0009 of the specification), comprising: a catalytic flue gas desulfurization device, comprising a desulfurization reactor, the desulfurization reactor having an air inlet for flue gas to be desulfurized, an exhaust port for desulfurized flue gas, a desulfurization catalyst regeneration liquid discharge port, and a desulfurization catalyst loading space located in the desulfurization reactor, the desulfurization reactor is provided with a desulfurization catalyst regeneration liquid spraying device for washing and regenerating the desulfurization catalyst in the desulfurization catalyst loading space, during desulfurization, the flue gas enters the desulfurization reactor from the air inlet for the flue gas to be desulfurized, is desulfurized by the desulfurization catalyst, and is then discharged from the exhaust port for the desulfurized flue gas, the sulfur dioxide in the flue gas reacts on the desulfurization catalyst to form sulfuric acid when passing through the desulfurization catalyst, When the desulfurization catalyst is washed and regenerated, the sulfuric acid enters the desulfurization catalyst regeneration liquid and is discharged from the desulfurization catalyst regeneration liquid discharge port; an SCR denitration device comprises an SCR denitration reactor, the SCR denitration reactor has an air inlet for flue gas to be denitrated, an exhaust port for flue gas that has been denitrated, and a denitration catalyst loading space located in the SCR denitration reactor, the denitration catalyst loading space is used to load the denitration catalyst, the denitration catalyst can adopt an activated carbon-based denitration catalyst, the operating temperature of the activated carbon-based denitration catalyst is 120°C-200°C, during denitration, the flue gas mixed with the denitration reducing agent enters the SCR denitration reactor from the air inlet for the flue gas to be denitrated, and then is denitrated by the denitration catalyst and discharged from the exhaust port for the denitrated flue gas, and the exhaust port for the desulfurized flue gas is connected to the air inlet for the flue gas to be denitrated.

[0003] In the above-mentioned flue gas desulfurization and denitrification system, the desulfurization reactor of the catalytic flue gas desulfurization device utilizes the principle of catalytic flue gas desulfurization (that is, sulfur dioxide, water, and oxygen in the flue gas are adsorbed on the pretreatment catalyst and react to generate sulfuric acid under the catalytic action of the active components) to remove sulfur dioxide from the flue gas to be denitrified. The flue gas to be denitrified entering the desulfurization reactor must contain a certain amount of water vapor (usually ≥8 vol.%). The inventors found that the flue gas discharged from the desulfurization reactor still contains water vapor. After entering the SCR denitrification reactor with the flue gas to be denitrified, it will affect the denitrification catalyst, thereby reducing the denitrification efficiency. Further research found that due to its strong polar characteristics, water molecules will react with NH 3The reaction gases compete for adsorption on the surface of the activated carbon-based denitrification catalyst, occupying the active sites originally used for the catalytic reaction; at the same time, the continued presence of water vapor will cause the activated carbon particles to agglomerate and reduce the specific surface area, making its pore structure loose and reducing the number of effective active sites; more importantly, water molecules may also react with the active ingredients on the surface of the activated carbon-based denitrification catalyst or promote the diffusion of certain toxic substances (such as alkali metals) into the activated carbon, resulting in the loss or conversion of active ingredients. These combined effects ultimately reduce the catalytic conversion efficiency of the activated carbon-based denitrification catalyst for nitrogen oxides. Summary of the invention

[0004] The purpose of the present invention is to provide an improved flue gas desulfurization and denitrification system to solve the technical problem that water vapor in the flue gas to be denitrified affects the denitrification catalyst and thus reduces the denitrification efficiency.

[0005] Provided is a flue gas desulfurization and denitrification system, comprising: a catalytic flue gas desulfurization device, comprising a desulfurization reactor, the desulfurization reactor having a flue gas inlet to be desulfurized, a flue gas exhaust port for desulfurized flue gas, a desulfurization catalyst regeneration liquid discharge port, and a desulfurization catalyst loading space located in the desulfurization reactor, the desulfurization reactor is provided with a desulfurization catalyst regeneration liquid spraying device for washing and regenerating the desulfurization catalyst in the desulfurization catalyst loading space, during desulfurization, the flue gas enters the desulfurization reactor from the flue gas inlet to be desulfurized, is desulfurized by the desulfurization catalyst, and is then discharged from the desulfurized flue gas exhaust port, the sulfur dioxide in the flue gas reacts on the desulfurization catalyst when passing through the desulfurization catalyst to form sulfuric acid, the sulfuric acid enters the desulfurization catalyst regeneration liquid and is discharged from the desulfurization catalyst regeneration liquid discharge port when the desulfurization catalyst is washed and regenerated, and the sulfur dioxide content in the flue gas discharged from the desulfurized flue gas exhaust port is 100 mg / Nm 3 The following is an SCR denitration device, comprising an SCR denitration reactor, wherein the SCR denitration reactor has an air inlet for flue gas to be denitrated, an exhaust port for flue gas that has been denitrated, and a denitration catalyst loading space located in the SCR denitration reactor, wherein the denitration catalyst loading space is used to load a denitration catalyst, wherein the denitration catalyst adopts an activated carbon-based denitration catalyst, and the operating temperature of the activated carbon-based denitration catalyst is 120°C-200°C. During denitration, flue gas mixed with a denitration reducing agent enters the SCR denitration reactor from the air inlet for flue gas to be denitrated, and then is denitrated by the denitration catalyst and then discharged from the exhaust port for flue gas that has been denitrated, and the exhaust port for flue gas that has been denitrated is connected to the air inlet for flue gas to be denitrated; the exhaust port for flue gas that has been desulfurized is connected to the air inlet for flue gas to be denitrated via the flue gas dehumidification device, and the flue gas dehumidification device is used to reduce the water vapor content in the flue gas entering the air inlet for flue gas to be denitrated.

[0006] By arranging a flue gas dehumidification device between the exhaust port of the desulfurized flue gas and the air inlet of the flue gas to be denitrified, the water vapor content of the flue gas entering the SCR denitrification reactor is effectively reduced, avoiding the influence of water vapor on the activated carbon-based denitrification catalyst (such as making the pore structure loose), ensuring the sufficient contact between nitrogen oxides and the denitrification catalyst, thereby maintaining a high denitrification efficiency; at the same time, since the flue gas dehumidification device is arranged after the flue gas is discharged from the desulfurization reactor, it will not affect the water vapor content required for catalytic flue gas desulfurization, thereby ensuring the desulfurization effect of the flue gas desulfurization and denitrification system.

[0007] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments. Additional aspects and advantages provided by the present invention will be partially given in the following description, partially become apparent from the following description, or be learned through practice. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The drawings constituting a part of this specification are used to assist the understanding of the present invention. The contents provided in the drawings and the related descriptions in this specification can be used to explain the present invention, but do not constitute improper limitations on the present invention.

[0009] Figure 1 The present invention is a schematic diagram of the principle of a flue gas desulfurization and denitrification system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0010] The present invention is described clearly and completely below in conjunction with the accompanying drawings. A person skilled in the art will be able to implement the present invention based on these descriptions. Before describing the present invention in conjunction with the accompanying drawings, it should be particularly noted that:

[0011] The technical solutions and technical features provided in each section, including the following description, can be combined with each other without conflict. In addition, where possible, these technical solutions, technical features and related combinations can be assigned specific technical themes and protected by relevant patents.

[0012] The embodiments of the present invention involved in the following description are generally only a part of the embodiments rather than all the embodiments. Based on these embodiments, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of patent protection.

[0013] The terms "include", "comprises", "have" and any variations thereof in this specification and the corresponding claims and related parts are intended to cover non-exclusive inclusions. Other related terms and units can be reasonably interpreted based on the relevant content provided in this specification.

[0014] Figure 1FIG. 1 is a schematic diagram of the principle of a flue gas desulfurization and denitrification system according to an embodiment of the present invention. Figure 1 As shown, the flue gas desulfurization and denitrification system comprises: a catalytic flue gas desulfurization device 1, comprising a desulfurization reactor, the desulfurization reactor having an air inlet for flue gas to be desulfurized, an exhaust port for desulfurized flue gas, a desulfurization catalyst regeneration liquid discharge port and a desulfurization catalyst loading space located in the desulfurization reactor, the desulfurization reactor is provided with a desulfurization catalyst regeneration liquid spraying device for washing and regenerating the desulfurization catalyst 11 in the desulfurization catalyst loading space, during desulfurization, the flue gas enters the desulfurization reactor from the air inlet for the flue gas to be desulfurized, is desulfurized by the desulfurization catalyst, and is then discharged from the exhaust port of the desulfurized flue gas, the sulfur dioxide in the flue gas reacts on the desulfurization catalyst 11 when passing through the desulfurization catalyst 11 to form sulfuric acid, the sulfuric acid enters the desulfurization catalyst regeneration liquid and is discharged from the exhaust port of the desulfurized flue gas when the desulfurization catalyst is washed and regenerated, and the sulfur dioxide content in the flue gas discharged from the exhaust port of the desulfurized flue gas is 100 mg / Nm 3 Below (preferably 50 mg / Nm 3 The SCR denitration device 2 includes an SCR denitration reactor, the SCR denitration reactor has an air inlet for flue gas to be denitrated, an exhaust port for flue gas that has been denitrated, and a denitration catalyst loading space located in the SCR denitration reactor, the denitration catalyst loading space is used to load a denitration catalyst 21, the denitration catalyst 21 adopts an activated carbon-based denitration catalyst, the operating temperature of the activated carbon-based denitration catalyst is 120°C-200°C, and a denitration reducing agent (NH 3 ) enters the SCR denitrification reactor from the flue gas inlet to be denitrified and then is discharged from the denitrified flue gas exhaust port after being denitrified by the denitrified flue gas catalyst 21, and the desulfurized flue gas exhaust port is connected to the flue gas inlet to be denitrified; the desulfurized flue gas exhaust port and the flue gas inlet to be denitrified are connected through the flue gas dehumidification device, and the flue gas dehumidification device is used to reduce the water vapor content in the flue gas entering the flue gas inlet to be denitrified.

[0015] Generally speaking, the sulfur dioxide concentration of the flue gas at the inlet of the flue gas to be desulfurized is 300 mg / Nm 3 -2000mg / Nm 3 In addition, the desulfurization catalyst is usually an activated carbon-based desulfurization catalyst.

[0016] By arranging a flue gas dehumidification device between the exhaust port of the desulfurized flue gas and the air inlet of the flue gas to be denitrified, the water vapor content of the flue gas entering the SCR denitrification reactor is effectively reduced, avoiding the influence of water vapor on the activated carbon-based denitrification catalyst (such as making the pore structure loose), ensuring the sufficient contact between nitrogen oxides and the denitrification catalyst, thereby maintaining a high denitrification efficiency; at the same time, since the flue gas dehumidification device is arranged after the flue gas is discharged from the desulfurization reactor, it will not affect the water vapor content required for catalytic flue gas desulfurization, thereby ensuring the desulfurization effect of the flue gas desulfurization and denitrification system.

[0017] Specifically, the flue gas dehumidification device adopts a condenser 3, and the condenser 3 is connected to the air inlet of the flue gas to be denitrified through a heater 4.

[0018] The heater 4 uses water vapor as a heat source (ie, the heater 4 is a steam heater), and the water vapor comes from a public steam source of the factory where the flue gas desulfurization and denitrification system is located.

[0019] In addition, the SCR denitration reactor is provided with a denitration catalyst regeneration liquid spraying device for washing and regenerating the denitration catalyst 21 in the denitration catalyst filling space. The SCR denitration reactor also has a denitration catalyst regeneration liquid discharge port. When the denitration catalyst is washed and regenerated, the denitration catalyst regeneration liquid acts on the denitration catalyst through the denitration catalyst regeneration liquid spraying device and is discharged from the denitration catalyst regeneration liquid discharge port.

[0020] At the same time, the SCR denitrification device 2 further includes a drying device, which includes a blower 5 and a drying gas distribution network. The blower 5 and the heater 4 can be connected to the SCR denitrification reactor through the drying gas distribution network, so that the airflow generated by the blower 5 is heated by the heater 4 to form drying gas and enters the SCR denitrification reactor after the denitrification catalyst is washed and regenerated and passes through the denitrification catalyst 21 of the SCR denitrification reactor. When the drying gas passes through the denitrification catalyst, the denitrification catalyst regeneration liquid attached to the denitrification catalyst evaporates and is discharged from the SCR denitrification reactor, so that the SCR denitrification reactor can quickly resume working condition.

[0021] Furthermore, the blower 5 and the heater 4 can also be connected to the desulfurization reactor through the drying gas distribution pipeline network, so that the airflow generated by the blower 5 is heated by the heater 4 to form drying gas and enters the desulfurization reactor after the desulfurization catalyst is washed and regenerated and passes through the desulfurization catalyst 11 of the desulfurization reactor. When the drying gas passes through the desulfurization catalyst, the desulfurization catalyst regeneration liquid attached to the desulfurization catalyst evaporates and is discharged from the desulfurization reactor, so that the desulfurization reactor can quickly resume working condition.

[0022] The drying gas distribution pipeline network can simultaneously or sequentially input the drying gas into the pretreatment reactor and the SCR denitration reactor.

[0023] like Figure 1 As shown, in this embodiment, a first valve K1 is provided at the air inlet of the flue gas to be desulfurized, a second valve K2 is provided on the flue between the condenser and the heater, a third valve K3 is provided on the flue between the heater and the air inlet of the flue gas to be denitrified, and a fourth valve K4 is provided at the exhaust port of the flue gas that has been denitrified; the drying gas distribution pipeline includes an air inlet pipeline connected between the blower 5 and the heater 4, a first exhaust pipeline connected between the heater 4 and the air inlet of the flue gas to be desulfurized, and a second exhaust pipeline connected between the heater 4 and the air inlet of the flue gas to be denitrified, a fifth valve K5 is provided on the air inlet pipeline, a sixth valve K6 is provided on the first exhaust pipeline, and a seventh valve K7 is provided on the second exhaust pipeline, and the sixth valve K6 and the seventh valve K7 are flow regulating valves; an air guide pipeline is also connected between the exhaust port of the desulfurized flue gas and the exhaust port of the denitrified flue gas, and an eighth valve K8 is provided on the air guide pipeline.

[0024] When the first valve K1, the second valve K2, the third valve K3 and the fourth valve K4 are opened, Figure 1 When the other valves are closed, the flue gas first passes through the desulfurization reactor, then enters the condenser 3 for deep dehumidification and is heated by the steam heater; when the steam heater is heated to a temperature of 120-200°C, the dehumidified flue gas is mixed with NH 3 After the desulfurization catalyst 11 and the denitration catalyst 21 are sprayed and washed, the first valve K1, the second valve K2, the third valve K3, and the fourth valve K4 are closed, and the fifth valve K5, the sixth valve K6, the seventh valve K7, and the eighth valve K8 are opened. The drying system (composed of the blower 7, the heater 6, and the drying gas distribution network) serves the drying of the corresponding catalysts in the desulfurization reactor and the SCR denitration reactor at the same time.

[0025] The above is a description of the relevant contents of the present invention. A person skilled in the art will be able to implement the present invention based on these descriptions. Based on the above contents of this specification, all other embodiments obtained by a person skilled in the art without making creative work should fall within the scope of the present invention.

Claims

1. Flue gas desulfurization and denitrification system, including: A catalytic flue gas desulfurization device comprises a desulfurization reactor, wherein the desulfurization reactor has an air inlet for flue gas to be desulfurized, an exhaust port for desulfurized flue gas, a desulfurization catalyst regeneration liquid discharge port and a desulfurization catalyst loading space located in the desulfurization reactor, wherein the desulfurization reactor is provided with a desulfurization catalyst regeneration liquid spraying device for washing and regenerating the desulfurization catalyst in the desulfurization catalyst loading space, wherein during desulfurization, the flue gas enters the desulfurization reactor from the air inlet for flue gas to be desulfurized, is desulfurized by the desulfurization catalyst and is then discharged from the exhaust port for the desulfurized flue gas, wherein the sulfur dioxide in the flue gas reacts on the desulfurization catalyst to form sulfuric acid when passing through the desulfurization catalyst, and when the desulfurization catalyst is washed and regenerated, the sulfuric acid enters the desulfurization catalyst regeneration liquid and is discharged from the exhaust port for the desulfurized flue gas, and the sulfur dioxide content in the flue gas discharged from the exhaust port for the desulfurized flue gas is 100 mg / Nm 3 The following is an SCR denitration device, comprising an SCR denitration reactor, wherein the SCR denitration reactor has an air inlet for flue gas to be denitrated, an exhaust port for flue gas that has been denitrated, and a denitration catalyst loading space located in the SCR denitration reactor, wherein the denitration catalyst loading space is used to load a denitration catalyst, wherein the denitration catalyst adopts an activated carbon-based denitration catalyst, and the operating temperature of the activated carbon-based denitration catalyst is 120°C-200°C. During denitration, the flue gas mixed with a denitration reducing agent enters the SCR denitration reactor from the air inlet for flue gas to be denitrated, and then is denitrated by the denitration catalyst and then discharged from the exhaust port for flue gas that has been denitrated, and the exhaust port for flue gas that has been denitrated is connected to the air inlet for flue gas to be denitrated; characterized in that: the exhaust port for flue gas that has been denitrated is connected to the air inlet for flue gas to be denitrated via the flue gas dehumidification device, and the flue gas dehumidification device is used to reduce the water vapor content in the flue gas entering the air inlet for flue gas to be denitrated.

2. The flue gas desulfurization and denitrification system according to claim 1, characterized in that: The flue gas dehumidification device adopts a condenser, and the condenser is connected to the air inlet of the flue gas to be denitrated through a heater.

3. The flue gas desulfurization and denitrification system according to claim 2, characterized in that: The heater uses water vapor as a heat source, and the water vapor comes from a public steam source of the factory where the flue gas desulfurization and denitrification system is located.

4. The flue gas desulfurization and denitrification system according to claim 2, characterized in that: The SCR denitration reactor is provided with a denitration catalyst regeneration liquid spraying device for washing and regenerating the denitration catalyst in the denitration catalyst filling space. The SCR denitration reactor also has a denitration catalyst regeneration liquid discharge port. When the denitration catalyst is washed and regenerated, the denitration catalyst regeneration liquid acts on the denitration catalyst through the denitration catalyst regeneration liquid spraying device and is discharged from the denitration catalyst regeneration liquid discharge port.

5. The flue gas desulfurization and denitrification system according to claim 4, characterized in that: It also includes a drying device, which includes a blower and a drying gas distribution pipeline. The blower and the heater can be connected to the SCR denitration reactor through the drying gas distribution pipeline, so that the airflow generated by the blower is heated by the heater to form drying gas and enters the SCR denitration reactor after the denitration catalyst is washed and regenerated, and passes through the denitration catalyst of the SCR denitration reactor. When the drying gas passes through the denitration catalyst, the denitration catalyst regeneration liquid attached to the denitration catalyst evaporates and is discharged from the SCR denitration reactor.

6. The flue gas desulfurization and denitrification system according to any one of claims 2 to 5, characterized in that: It also includes a drying device, which includes a blower and a drying gas distribution pipeline. The blower and the heater can be connected to the desulfurization reactor through the drying gas distribution pipeline, so that the airflow generated by the blower is heated by the heater to form drying gas and enters the desulfurization reactor after the desulfurization catalyst is washed and regenerated and passes through the desulfurization catalyst of the desulfurization reactor. When the drying gas passes through the desulfurization catalyst, the desulfurization catalyst regeneration liquid attached to the desulfurization catalyst evaporates and is discharged from the desulfurization reactor.

7. The flue gas desulfurization and denitrification system according to claim 6, characterized in that: The drying gas distribution network simultaneously or sequentially inputs the drying gas into the desulfurization reactor and the SCR denitration reactor.

8. The flue gas desulfurization and denitrification system according to claim 7, characterized in that: A first valve is provided at the air inlet of the flue gas to be desulfurized, a second valve is provided on the flue between the condenser and the heater, a third valve is provided on the flue between the heater and the air inlet of the flue gas to be denitrified, and a fourth valve is provided at the exhaust port of the flue gas that has been denitrified; the drying gas distribution pipeline includes an air inlet pipeline connected between the blower and the heater, a first exhaust pipeline connected between the heater and the air inlet of the flue gas to be desulfurized, and a second exhaust pipeline connected between the heater and the air inlet of the flue gas to be denitrified, a fifth valve is provided on the air inlet pipeline, a sixth valve is provided on the first exhaust pipeline, and a seventh valve is provided on the second exhaust pipeline, and the sixth valve and the seventh valve are flow regulating valves; an air guide pipeline is also connected between the exhaust port of the desulfurized flue gas and the exhaust port of the denitrified flue gas, and an eighth valve is provided on the air guide pipeline.

9. The flue gas desulfurization and denitrification system according to claim 1, characterized in that: The desulfurization catalyst is an activated carbon-based desulfurization catalyst.

10. The flue gas desulfurization and denitrification system according to claim 1, characterized in that: The sulfur dioxide content in the flue gas discharged from the desulfurized flue gas exhaust port is 50 mg / Nm 3 the following.

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