Active coke desulfurization and denitrification system

Abstract

The utility model discloses an active coke desulfurization and denitrification system which comprises a desulfurization and denitrification tower and a regeneration tower, the desulfurization and denitrification tower is provided with a flue gas inlet and an active coke outlet, the flue gas inlet is connected with a first ammonia modification pipeline, and the active coke outlet is connected to an inlet of the regeneration tower and used for conveying active coke; the inlet of the regeneration tower is also connected with a second ammonia modification pipeline; wherein the first ammonia modification pipeline and the second ammonia modification pipeline are used for introducing ammonia modification gas to activate the active coke. According to the system disclosed by the utility model, different atmosphere ammonia gases can be introduced into different positions of the desulfurization and denitrification tower and the regeneration tower, and ammonia modification is carried out on the active coke, so that the denitrification performance of the active coke is further improved, and therefore, under the same removal efficiency requirement, the ammonia spraying amount of the system can be reduced, the operation cost is reduced, the escape of tail discharged ammonia is reduced, and the environmental protection requirement is met.

Description

Technical Field

[0001] The utility model relates to the technical field of flue gas purification, in particular to an activated coke desulfurization and denitrification system. Background Art

[0002] As the pressure of environmental protection continues to increase, the treatment of sintering flue gas desulfurization and denitrification has become particularly important. Currently, one of the mainstream sintering flue gas desulfurization and denitrification processes at home and abroad is activated coke desulfurization and denitrification. The principle is that activated coke has adsorption properties and catalytic activity, which can adsorb SO2 and catalytically treat NOx. The process is as follows: the flue gas first enters the moving bed absorption tower containing the activated coke module for desulfurization and denitrification. The absorption tower is generally divided into two parts: desulfurization and denitrification. Generally, the first part is desulfurization and the second part is denitrification. After adsorption saturation, the activated coke module recovers the sulfur dioxide obtained by thermal desorption for the production of sulfuric acid, ammonium sulfate and other products. Among them, the performance of activated coke is particularly critical, and the replacement of activated coke is also a major cost of this process.

[0003] In the actual operation of activated coke flue gas purification projects, many companies inject excessive amounts of ammonia to meet denitrification standards, resulting in ammonia escape. The flue gas tailing problem caused by excessive ammonia escape has received increasing attention. The newly promulgated "Action Plan for Continuous Improvement of Air Quality," implemented in November 2023, explicitly calls for "strengthening the prevention and control of ammonia escape from industrial flue gas desulfurization and denitrification." The effectiveness of ammonia escape control is directly related to the improvement of a company's environmental emission standards and environmental quality. With increasingly stringent environmental regulations, the requirements for ammonia escape control technology are also increasing. It is necessary to ensure the appropriate amount of ammonia added during the denitrification process to reduce the occurrence of ammonia escape.

[0004] Therefore, how to improve the performance of activated coke, enhance the efficiency of desulfurization and denitrification, and reduce ammonia escape is the key to improving the existing activated coke desulfurization and denitrification system. Summary of the Invention

[0005] In order to solve the above problems, the utility model aims to provide an activated coke desulfurization and denitrification system that can improve the performance of activated coke, increase the desulfurization and denitrification efficiency, and reduce ammonia escape.

[0006] In order to achieve the above-mentioned purpose, an activated coke desulfurization and denitrification system is provided, and the technical solutions adopted are as follows:

[0007] An activated coke desulfurization and denitrification system comprises a desulfurization and denitrification tower and a regeneration tower, wherein the desulfurization and denitrification tower has a flue gas inlet and an activated coke outlet, wherein the flue gas inlet is connected to a first ammonia modification pipeline, and the activated coke outlet is connected to the inlet of the regeneration tower for conveying activated coke; the inlet of the regeneration tower is also connected to a second ammonia modification pipeline; wherein the first ammonia modification pipeline and the second ammonia modification pipeline are used to introduce ammonia of a certain concentration to modify the activated coke.

[0008] Preferably, the first ammonia modification pipeline is used to introduce ammonia-air mixed gas.

[0009] Furthermore, the first ammonia modification pipeline is connected to an ammonia source and an air blower.

[0010] Preferably, the second ammonia modification pipeline is used to introduce ammonia-nitrogen mixed gas.

[0011] Furthermore, the second ammonia modification pipeline is connected to an ammonia source and a nitrogen source.

[0012] Furthermore, the ammonia source is connected to the first ammonia modification pipeline through an ammonia regulating valve; the air blower is connected to the first ammonia modification pipeline through an air regulating valve, and the first ammonia modification pipeline is connected to the flue gas inlet along the ammonia-air mixed gas conveying direction in one direction and to the transition air chamber of the desulfurization and denitrification tower in the other direction.

[0013] Furthermore, ammonia-air mixed gas regulating valves are respectively provided on the two first ammonia modified pipelines connected to the flue gas inlet and the transition gas chamber, and the ammonia-air mixed gas regulating valves are used to control the gas flow rate entering the flue gas inlet and the transition gas chamber to be in the ratio of (1-3): (7-9).

[0014] Furthermore, the ammonia source is connected to a second ammonia modification pipeline through an ammonia regulating valve, and the nitrogen source is connected to the second ammonia modification pipeline through a nitrogen regulating valve; the second ammonia modification pipeline is respectively connected to the inlet of the regeneration tower and the outlet of the regeneration tower along the conveying direction of the ammonia-nitrogen mixed gas; the ammonia concentration in the ammonia-nitrogen mixed gas introduced into the inlet and outlet of the regeneration tower is controlled to be less than 10% vol by the ammonia regulating valve and the nitrogen regulating valve.

[0015] Furthermore, an ammonia-nitrogen mixed gas regulating valve is provided on the second ammonia modification pipeline, and the carrier gas flow rate is controlled to be less than 2 m / min by the ammonia-nitrogen mixed gas regulating valve.

[0016] Preferably, the inlet discharger and the outlet discharger of the regeneration tower are both connected to gas-sealed nitrogen.

[0017] Furthermore, the gas-sealing nitrogen gas is an ammonia-nitrogen mixed gas transported by the second ammonia-modified pipeline.

[0018] Preferably, the regeneration tower is connected to a regeneration fan.

[0019] Beneficial effects:

[0020] 1) The system of the utility model can introduce different atmospheric ammonia into different positions of the desulfurization and denitrification tower and the regeneration tower, and at the same time perform ammonia modification on the activated coke to further improve the denitrification performance of the activated coke. Thus, under the same removal efficiency requirements, the amount of ammonia sprayed by the system can be reduced, the operating cost can be reduced, and the escape of tail ammonia can be reduced to meet environmental protection requirements.

[0021] 2) This system can adjust the ratio of the ammonia-air mixture at the flue gas inlet and the ammonia-air mixture in the transition gas chamber, so that the ammonia added at the flue gas inlet reacts with sulfur dioxide in the flue gas to form a small amount of ammonium sulfate, which is then decomposed in the regeneration tower to form new active centers, which is beneficial to improving the denitrification rate.

[0022] 3) This system can adjust the ammonia concentration in the ammonia-nitrogen mixed gas at the regeneration tower inlet, and adjust the carrier gas flow rate of the ammonia-nitrogen mixed gas, so that part of the ammonia reacts with the sulfur dioxide gas released during the regeneration process to form an intermediate substance to modify the surface of the activated coke. The oxygen-containing functional groups on the surface of the activated coke change, undergo secondary modification, and form new active sites. Part of the ammonia is decomposed into nitrogen by high temperature, and part is drawn out by the regeneration fan along with the regeneration gas into the subsequent process section. The increase in ammonia in the regeneration tail gas is less than 5% vol, which has almost no effect on the treatment of the subsequent process section.

[0023] 4) The denitrification performance curve of activated coke modified with ammonia in this system changes. Conventional thermal regeneration and activated coke denitrification show tail NOx levels rising, then falling, and then stabilizing. However, the denitrification process with ammonia modification is as follows: after an initial period of ammonia adsorption from the gas phase into the activated coke pores and participation in the reaction, the NOx on the modified activated coke quickly reacts on the surface and gradually approaches equilibrium, resulting in a relatively stable denitrification rate. This system can address the denitrification lag commonly seen in current projects, particularly during initial startup or after shutdown. The system also responds quickly, enabling NOx emissions to quickly meet emission targets. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be further described below with reference to the accompanying drawings.

[0025] Figure 1 This is a schematic diagram of the activated coke desulfurization and denitrification system of the utility model.

[0026] Figure 2 This is a comparison chart of the denitrification efficiency of the activated coke desulfurization and denitrification system using the utility model and the denitrification efficiency of conventional heat treatment.

[0027] Description of Figure Numbers:

[0028] 1-Ammonia source; 10, 11-Ammonia regulating valve; 2-Air fan; 20-Air regulating valve; 3-Desulfurization and denitrification tower; 4-Transition air chamber; 5-Flue gas inlet; 6-Flue gas outlet; 7-Regeneration tower; 8-Regeneration fan; 9-Nitrogen source; 90-Nitrogen regulating valve; A-First ammonia modification pipeline; A0, A1-Ammonia-air mixed gas regulating valve; B-Second ammonia modification pipeline; B0, B1, B2, B3-Ammonia-nitrogen mixed gas regulating valve. DETAILED DESCRIPTION

[0029] The present invention is further explained in detail below with reference to the accompanying drawings and specific embodiments.

[0030] According to a preferred embodiment of the present invention, Figure 1 As shown, an activated coke desulfurization and denitrification system includes a desulfurization and denitrification tower 3 and a regeneration tower 7. The desulfurization and denitrification tower 3 has a flue gas inlet 5 and an activated coke outlet. The flue gas inlet is connected to a first ammonia modified gas pipeline A, and the activated coke outlet is connected to the inlet of the regeneration tower 7 for transporting activated coke; the inlet of the regeneration tower 7 is also connected to a second ammonia modification pipeline B; wherein, the first ammonia modification pipeline A and the second ammonia modification pipeline B are used to introduce a certain concentration of ammonia to modify the activated coke.

[0031] According to this embodiment, the flue gas to be treated enters the desulfurization and denitrification tower 3 from the flue gas inlet, and the flue gas treated with activated coke is discharged from the flue gas outlet 6 of the desulfurization and denitrification tower 3. During the desulfurization and denitrification treatment process, ammonia-modified gas can be added to the flue gas inlet 5 of the desulfurization and denitrification tower 3 and the inlet of the regeneration tower 7 respectively, so as to simultaneously perform ammonia modification on the activated coke in the tower, change the surface properties of the activated coke, and improve the denitrification performance of the activated coke. Under the same removal efficiency requirement, the ammonia injection amount of the desulfurization and denitrification system is reduced by about 20%, which meets the tail nitrogen oxide emission requirements, and at the same time, the ammonia escape can be reduced by about 30%.

[0032] As another preferred embodiment, the first ammonia modification pipeline A is used to introduce ammonia-air mixed gas; the second ammonia modification pipeline B is used to introduce ammonia-nitrogen mixed gas.

[0033] Based on this, in this embodiment, the reducing agent ammonia is divided into two types, namely, ammonia-air mixed gas and ammonia-nitrogen mixed gas. The ammonia-air mixed gas is introduced into the flue gas inlet 5 and the ammonia-nitrogen mixed gas is introduced into the regeneration tower 7 inlet. The activated coke can be modified with ammonia at the same time, thereby further optimizing the performance of the activated coke.

[0034] As another preferred embodiment, the first ammonia modification pipeline A is connected to an ammonia source 1 and an air blower 2. The second ammonia modification pipeline B is connected to a nitrogen source and is also connected to the ammonia source 1. The ammonia source 1 is connected to the first ammonia modification pipeline A via an ammonia regulating valve 10; the air blower 2 is connected to the first ammonia modification pipeline A via an air regulating valve 20. The first ammonia modification pipeline A is connected to the flue gas inlet 5 along the direction of conveying the ammonia-air mixed gas and to the transition gas chamber 4 of the desulfurization and denitrification tower 3 on the other side. Based on this embodiment, in addition to the flue gas inlet 5, ammonia-modified gas can also be added to the transition gas chamber 4 of the desulfurization and denitrification tower 3 to activate the activated coke and further optimize the performance of the activated coke.

[0035] In addition, an ammonia-air mixed gas regulating valve A0 / A1 is respectively provided on the two first ammonia modified pipes A connected to the flue gas inlet 5 and the transition gas chamber 4, and the ammonia-air mixed gas regulating valve A0 / A1 controls the gas flow rate entering the flue gas inlet 5 and the transition gas chamber 4 to be (1~3):(7~9).

[0036] The ammonia source 1 is connected to the second ammonia modification pipeline B through another ammonia regulating valve 11, and the nitrogen source 9 is connected to the second ammonia modification pipeline B through a nitrogen regulating valve 90; the second ammonia modification pipeline B is respectively connected to the inlet of the regeneration tower 7 and the outlet of the regeneration tower 7 along the conveying direction of the ammonia-nitrogen mixed gas; the ammonia concentration in the ammonia-nitrogen mixed gas introduced into the inlet and outlet of the regeneration tower is controlled to be less than 10% vol by the ammonia regulating valve 11 and the nitrogen regulating valve 90.

[0037] The second ammonia modification pipeline B is provided with an ammonia-nitrogen mixed gas regulating valve, which controls the carrier gas flow rate entering the regeneration tower inlet through the ammonia-nitrogen mixed gas regulating valve B0 and the carrier gas flow rate entering the regeneration tower outlet through the ammonia-nitrogen mixed gas regulating valve B1 to be less than 2m / min.

[0038] To reduce the formation of ammonium sulfate in the first-stage bed of the desulfurization and denitrification tower 3, the volume ratio of the ammonia-air mixed gas at the flue gas inlet 5 and the transition chamber 4 in the desulfurization and denitrification tower 3 can be controlled to (1-3): (7-9). This allows a small amount of ammonia to be introduced into the flue gas inlet 5. If the sulfur dioxide concentration in the flue gas is high, it can easily clog the air intake grille, hindering the operation of the project. Based on this, the ammonia added at the flue gas inlet reacts with the sulfur dioxide in the flue gas to form a small amount of ammonium sulfate. The saturated activated coke is then transported to the regeneration tower 7 for ammonium sulfate decomposition, forming new active centers, which is conducive to improving the denitrification rate. To ensure the ammonia modification effect, the ammonia concentration in the ammonia-nitrogen mixed gas introduced into the inlet / outlet of the regeneration tower 7 is controlled to be less than 10% vol, and the carrier gas flow rate is within the range of less than 2 m / min. The ammonia-nitrogen mixed gas enters the regeneration tower 7 from the low-temperature section (e.g., 100°C) to the high-temperature section (e.g., 400°C) of the heating section of the regeneration tower 7. Part of the ammonia reacts with the sulfur dioxide gas released during the regeneration process to form an intermediate substance to modify the surface of the activated coke. The oxygen-containing functional groups on the surface of the activated coke change, undergo secondary modification, and form new active sites. Part of it decomposes into nitrogen at high temperature, and part of it is drawn out by the regeneration blower 8 along with the regeneration gas into the subsequent process section. The increase in the proportion of ammonia in the regeneration tail gas is less than 5% vol, which has almost no effect on the treatment of the subsequent process section.

[0039] Therefore, the system of the utility model can realize ammonia modification of the activated coke by introducing different atmospheres of ammonia at the flue gas inlet 5 and the regeneration tower inlet 7, further improving the denitrification performance of the activated coke, reducing the amount of ammonia sprayed by the system under the same removal efficiency requirements, reducing the operating costs, and at the same time reducing the escape of tail ammonia to meet environmental protection requirements.

[0040] In addition to the inlet and outlet of the regeneration tower 7, the ammonia-nitrogen mixed gas is passed through and used as the gas-sealing nitrogen in synchronization; the inlet discharger 71 and the outlet discharger 72 of the regeneration tower 7 are both connected to the gas-sealing nitrogen. In order to further optimize the system settings, the inlet discharger 71 and the outlet discharger 72 of the regeneration tower 7 are connected to the second ammonia modification pipeline. Thereby, the second ammonia modification pipeline B is not only connected to the inlet / outlet of the regeneration tower 7 along the direction of the ammonia-nitrogen mixed gas transportation, but is also connected to the inlet discharger 71 and the outlet discharger 72 as the gas-sealing nitrogen, realizing the multi-channel sharing of the ammonia-nitrogen mixed gas, which is more efficient and reasonable. In addition, the carrier gas flow rate entering the inlet discharger 71 is controlled by the ammonia-nitrogen mixed gas regulating valve B2, and the carrier gas flow rate of the outlet discharger 72 is controlled by the ammonia-nitrogen mixed gas regulating valve B3.

[0041] To ensure the stable operation of the regeneration tower 7. The regeneration tower 7 is also connected to a regeneration blower 8 for extracting part of the regeneration tail gas.

[0042] Based on the application of the desulfurization and denitrification system of this utility model:

[0043] The denitrification performance curve of the activated coke modified with ammonia through the above system has changed:

[0044] During denitrification of activated coke after conventional thermal regeneration, the tail exhaust nitrogen oxide concentration first increases, then decreases, and then stabilizes.

[0045] The denitrification performance of ammonia regeneration in this system is as follows Figure 2 As shown (denitration efficiency on the vertical axis, time on the horizontal axis), ammonia first absorbs from the gas phase into the activated coke pores and participates in the reaction. Then, the modified activated coke rapidly reacts with nitrogen oxides on the surface, gradually approaching equilibrium, ultimately maintaining a relatively stable denitration rate. This solves the denitration lag problem commonly seen in current projects, such as the initial startup or after shutdown of activated coke desulfurization and denitration units. The system responds quickly, ensuring that nitrogen oxide emissions meet emission targets quickly.

[0046] The above embodiments are only used to further illustrate the technical solution of the present invention in detail and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by technicians in this field based on the above content of the present invention are all within the scope of protection of the present invention.

Claims

1. An activated coke desulfurization and denitrification system, characterized in that: It includes a desulfurization and denitrification tower and a regeneration tower. The desulfurization and denitrification tower has a flue gas inlet and an activated coke outlet. The flue gas inlet is connected to a first ammonia modification pipeline, and the activated coke outlet is connected to the inlet of the regeneration tower for transporting activated coke; the inlet of the regeneration tower is also connected to a second ammonia modification pipeline; wherein, the first ammonia modification pipeline and the second ammonia modification pipeline are used to introduce a certain concentration of ammonia to modify the activated coke.

2. The activated coke desulfurization and denitrification system according to claim 1, characterized in that: The first ammonia modification pipeline is used to introduce ammonia-air mixed gas; the first ammonia modification pipeline is connected to an ammonia source and an air blower.

3. The activated coke desulfurization and denitrification system according to claim 1, characterized in that: The second ammonia modification pipeline is used to introduce ammonia-nitrogen mixed gas, and the second ammonia modification pipeline is connected to an ammonia source and a nitrogen source.

4. The activated coke desulfurization and denitrification system according to claim 2, characterized in that: The ammonia source is connected to the first ammonia modification pipeline through an ammonia regulating valve; the air blower is connected to the first ammonia modification pipeline through an air regulating valve, and the first ammonia modification pipeline is connected to the flue gas inlet along the ammonia-air mixed gas conveying direction in one direction and to the transition air chamber of the desulfurization and denitrification tower in the other direction.

5. The activated coke desulfurization and denitrification system according to claim 4, characterized in that: Ammonia-air mixed gas regulating valves are respectively provided on the two first ammonia modified pipelines connected to the flue gas inlet and the transition gas chamber, and the ammonia-air mixed gas regulating valves are used to control the gas flow ratio entering the flue gas inlet and the transition gas chamber.

6. The activated coke desulfurization and denitrification system according to claim 3, characterized in that: The ammonia source is connected to the second ammonia modification pipeline through an ammonia regulating valve, and the nitrogen source is connected to the second ammonia modification pipeline through a nitrogen regulating valve; the second ammonia modification pipeline is respectively connected to the inlet of the regeneration tower and the outlet of the regeneration tower along the conveying direction of the ammonia-nitrogen mixed gas; the ammonia concentration in the ammonia-nitrogen mixed gas introduced into the inlet and outlet of the regeneration tower is controlled by the cooperation of the ammonia regulating valve and the nitrogen regulating valve.

7. The activated coke desulfurization and denitrification system according to claim 6, characterized in that: The second ammonia modification pipeline is provided with an ammonia-nitrogen mixed gas regulating valve, and the maximum carrier gas flow rate is set to 2 m / min through the ammonia-nitrogen mixed gas regulating valve.

8. The activated coke desulfurization and denitrification system according to claim 1, characterized in that: The inlet discharger and the outlet discharger of the regeneration tower are both connected to gas sealing nitrogen.

9. The activated coke desulfurization and denitrification system according to claim 8, characterized in that: The inlet discharger and the outlet discharger of the regeneration tower are respectively connected to the second ammonia modification pipeline for receiving the transported ammonia-nitrogen mixed gas as gas sealing nitrogen.

10. The activated coke desulfurization and denitrification system according to claim 1, characterized in that: The regeneration tower is connected to a regeneration fan.

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