SCR coupled SNCR denitration system in high-sulfur environment and working method

Abstract

The invention relates to the technical field of SCR (Selective Catalytic Reduction) coupled SNCR (Selective Non-Catalytic Reduction) denitration, and discloses an SCR coupled SNCR denitration system in a high-sulfur environment, which comprises two C5 cyclones, two C4 cyclones, two C3 cyclones, two C2 cyclones, two C1 cyclones, a decomposing furnace, an SCR reactor, an SCR ammonia spraying module, an SNCR ammonia spraying module, two groups of SNCR spray guns, a plurality of SCR spray guns, a gas analyzer, an intelligent prediction distribution module and the like. The invention further provides an SCR coupling SNCR denitration working method in the high-sulfur environment, and the method comprises the following steps: S1, collection and analysis: collecting flue gas at an inlet and an outlet of a decomposing furnace and an outlet of a C1 cyclone cylinder in real time through a gas analyzer. The method not only solves the problem of avoiding an area where ammonia reacts with SO2 under a water vapor condition in a high-sulfur environment, but also can save the total ammonia water consumption, reduce the production cost and realize ammonia escape control and ultralow emission.

Description

Technical Field

[0001] The present invention relates to the technical field of SCR coupled with SNCR denitration, and particularly to an SCR coupled with SNCR denitration system and a working method under a high-sulfur environment. Background Art

[0002] The Ministry of Ecology and Environment has issued the Opinions on Promoting the Implementation of Ultra-low Emissions in the Cement Industry, clearly requiring that under the condition of a reference oxygen content of 10%, the hourly average nitrogen oxide emission concentration of cement kilns and kiln tail waste heat utilization systems shall not be higher than 50 mg / m 3 , and the ammonia slip ≤ 8 mg / m 3 , and some provinces have even put forward an emission requirement of 35 mg / m 3 . As the most stable nitrogen oxide ultra-low emission technology solution at present, the SCR denitration process has been widely used. Currently, SCR generally sprays ammonia assisted by the C1 cyclone or C2 cyclone. However, in a high-sulfur environment, most of the ammonia water sprayed at the C1 and C2 cyclones reacts with SO2 and fails to participate in the denitration reaction, resulting in a high overall ammonia water consumption for denitration, high usage costs, and difficulty in controlling ammonia slip emissions.

[0003] From the perspectives of the safety of storing solutions and saving operating costs, the cement industry normally uses ammonia water spraying for denitration, rather than spraying liquid ammonia similar to the power industry and evaporating it before entering the SCR denitration. The ammonia slip that has not reacted after the cement industry uses SNCR to spray ammonia for denitration at the C5 cyclone or the decomposition furnace enters the SCR reactor. When SNCR normally sprays ammonia, the ammonia-nitrogen molar ratio escaping to the SCR is low, resulting in low SCR denitration efficiency. The SNCR reaction temperature window is generally between 850 - 1000 °C. If excessive ammonia is sprayed in this area and the ammonia slip is allowed to enter the SCR for denitration, it is also a solution. However, in the case of a high ammonia-nitrogen ratio, a high local ammonia concentration will cause a large amount of ammonia to be adsorbed by the raw meal, and it will also increase the side reaction of NH3 oxidation to generate NO. The generation range of NH3 oxidation to generate NO is between a molar ratio of ammonia to oxygen of 1:1 to 4:1, and the higher the ammonia-nitrogen ratio, the more NH3 oxidation to generate NO. Most of the water vapor brought during the ammonia water spraying process will be adsorbed by the raw meal in each stage of the cyclone. The normal temperature range for the decomposition reaction of sulfides to generate SO2 is 400 - 600 °C.

[0004] In the case of a higher ammonia-nitrogen molar ratio, the SCR denitration efficiency is higher. For the SCR ammonia spraying in the cement industry, it is necessary to avoid directly spraying ammonia water at the SCR inlet to cause catalyst blockage, avoid the SNCR reaction temperature window, and avoid the area where ammonia reacts with SO2 under water vapor conditions in a high-sulfur environment. Summary of the Invention

[0005] (I) Technical Problems to be Solved

[0006] In view of the deficiencies of the prior art, the present invention provides an SCR coupled with SNCR denitration system and a working method under a high-sulfur environment, which solves the problems that in the case of a higher ammonia-nitrogen molar ratio, the SCR denitration efficiency is higher, the ammonia injection in the SCR of the cement industry should avoid directly injecting ammonia water at the SCR inlet to cause catalyst blockage, avoid the reaction temperature window of SNCR, and avoid the region where ammonia reacts with SO2 under the condition of water vapor in a high-sulfur environment.

[0007] (II) Technical solution

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] An SCR coupled with SNCR denitration system under a high-sulfur environment includes two C5 cyclones, two C4 cyclones, two C3 cyclones, two C2 cyclones, two C1 cyclones, a decomposition furnace, an SCR reactor, an SCR ammonia injection module, an SNCR ammonia injection module, two groups of SNCR spray guns, a plurality of SCR spray guns, a gas analyzer and an intelligent prediction and distribution module. The two C5 cyclones are respectively arranged on both sides of the decomposition furnace, and the decomposition furnace is connected to the two C5 cyclones through an air duct. The adjacent C5 cyclone, C4 cyclone, C3 cyclone, C2 cyclone and C1 cyclone are connected to each other through an air duct. The outlets of the two C1 cyclones are connected to the SCR reactor through a three-way air duct. The plurality of SCR spray guns are respectively arranged on the outlet pipelines of the two C3 cyclones and the two C4 cyclones. The SCR ammonia injection module is connected to the SCR spray guns through a pipeline. The two groups of SNCR spray guns are respectively arranged on the two C5 cyclones. The SNCR module is connected to the SNCR spray guns through a pipeline. The gas analyzer is arranged on the three-way pipe at the outlets of the decomposition furnace and the two C1 cyclones. The intelligent prediction and distribution module is connected to the SCR ammonia injection module and the SNCR ammonia injection module through an electric signal.

[0010] Further, the two C4 cyclones, C3 cyclones, C2 cyclones and C1 cyclones are respectively arranged on both sides of the decomposition furnace.

[0011] On the basis of the foregoing solution, the plurality of SCR spray guns are respectively located on the straight sections or conical sections of the C3 cyclone and the C4 cyclone bodies.

[0012] As a further solution of the present invention, the SNCR spray gun is located on the straight section or conical section of the C5 cyclone body.

[0013] Further, the gas analyzer is located at the inlet, outlet of the decomposition furnace and the outlet of the C1 cyclone.

[0014] On the basis of the foregoing solution, the intelligent prediction and distribution module synchronously collects the temperature of the decomposition furnace and the temperature data of the C5 cyclone, C4 cyclone, C3 cyclone, C2 cyclone, C1 cyclone, and the coal consumption data at the kiln tail.

[0015] As a further solution of the present invention, the number of the two groups of SNCR spray guns is two or more.

[0016] The present invention also provides a SCR coupling SNCR denitration working method in a high-sulfur environment, including the following steps:

[0017] S1: Acquisition and analysis, the flue gas at the inlet, outlet of the decomposition furnace and the outlet of the C1 cyclone is collected in real time by a gas analyzer, and the contents of SO2, NO X and O2 are analyzed, and the data is transmitted to the intelligent prediction and distribution module;

[0018] S2: Concentration prediction, the intelligent prediction and distribution system predicts the NOx and SO2 concentrations of each subsequent cyclone according to the real-time data of the gas analyzer, combined with the temperature of the decomposition furnace and the parameters of the temperatures of the C5 cyclone, C4 cyclone, C3 cyclone, C2 cyclone, C1 cyclone, and the coal consumption at the kiln tail.

[0019] S3: Intelligent distribution, the intelligent prediction and distribution module automatically distributes ammonia water to the SCR ammonia injection module and the SNCR ammonia injection module according to the predicted data in S2, and at the same time distributes different ammonia water dosages to the SCR spray guns on the C4 cyclone and the C3 cyclone.

[0020] S4: Real-time adjustment, by real-time adjusting the ammonia water dosage of the SCR spray guns on the C4 cyclone and the C3 cyclone, and gradually reducing the ammonia water dosage of the SNCR spray guns until dynamic balance is achieved under the condition that the outlet emission index meets the requirements.

[0021] The beneficial effects of the present invention are as follows:

[0022] 1. According to the reaction mechanism of SO2 and ammonia water, in a high-sulfur environment, by avoiding the temperature range where SO2 is released in large quantities, ammonia is injected at the C4 and C3 cyclones above 600 °C, and the time difference and regional concentration difference between ammonia and water evaporation are utilized to avoid the reaction of ammonia and SO2. The ammonia gas enters the SCR reactor and undergoes denitration reaction under the action of the catalyst, solving the problem of avoiding the area where ammonia reacts with SO2 under the condition of water vapor in a high-sulfur environment.

[0023] 2. The present invention uses the intelligent prediction and distribution module to predict and adjust the ammonia water dosage of the SCR spray guns corresponding to the C4 and C3 cyclones according to the real-time data of the gas analyzer, and gradually reduces the SNCR ammonia water dosage, giving play to the advantage of high SCR denitration efficiency, saving the total ammonia water dosage, reducing the production cost, and realizing ammonia slip control and ultra-low emissions. Description of the Drawings

[0024] Figure 1 It is a process layout diagram of an SCR coupled with SNCR denitration system under a high - sulfur environment of the present invention;

[0025] Figure 2 It is a schematic flow - structure diagram of a working method of SCR coupled with SNCR denitration under a high - sulfur environment of the present invention.

[0026] In the figure: 1. C5 cyclone; 2. C4 cyclone; 3. C3 cyclone; 4. C2 cyclone; 5. C1 cyclone; 6. decomposition furnace; 7. SCR reactor; 8. SCR ammonia injection module; 9. SNCR ammonia injection module; 10. SNCR spray gun; 11. SCR spray gun; 12. gas analyzer; 13. intelligent prediction and distribution module. Detailed Embodiments

[0027] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. It should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection", and "setting" should be understood in a broad sense. For those of ordinary skill in the art, the specific meanings of the above terms in this patent can be understood according to specific situations.

[0028] Embodiment 1

[0029] Refer to Figure 1 - Figure 2, an SCR coupled with SNCR denitration system in a high-sulfur environment, includes two C5 cyclones 1, two C4 cyclones 2, two C3 cyclones 3, two C2 cyclones 4, two C1 cyclones 5, a decomposition furnace 6, an SCR reactor 7, an SCR ammonia injection module 8, an SNCR ammonia injection module 9, two groups of SNCR spray guns 10, multiple SCR spray guns 11, a gas analyzer 12 and an intelligent prediction and distribution module 13. The two C5 cyclones 1 are respectively arranged on both sides of the decomposition furnace 6, and the decomposition furnace 6 is connected to the two C5 cyclones 1 through air ducts. The adjacent C5 cyclone 1, C4 cyclone 2, C3 cyclone 3, C2 cyclone 4 and C1 cyclone 5 are interconnected through air ducts. The outlets of the two C1 cyclones 5 are interconnected with the SCR reactor 7 through a three-way air duct. Multiple SCR spray guns 11 are respectively arranged on the outlet pipes of the two C3 cyclones 3 and the outlet pipes of the two C4 cyclones 2. The SCR ammonia injection module 8 is connected to the SCR spray guns 11 through a pipeline. The two groups of SNCR spray guns 10 are respectively arranged on the two C5 cyclones 1. The SNCR module 9 is connected to the SNCR spray guns 10 through a pipeline. The gas analyzer 12 is arranged on the three-way pipe at the outlets of the decomposition furnace 6 and the two C1 cyclones 5. The intelligent prediction and distribution module 13 is connected to the SCR ammonia injection module 8 and the SNCR ammonia injection module 9 through electrical signals. According to the reaction mechanism of SO2 and ammonia water, in a high-sulfur environment, by avoiding the temperature range where a large amount of SO2 is released, ammonia is injected at the C4 and C3 cyclones above 600 °C. Utilizing the time difference and regional concentration difference between the evaporation of ammonia and water, the reaction between ammonia and SO2 is avoided. The ammonia gas enters the SCR reactor and undergoes a denitration reaction under the action of a catalyst, solving the problem of avoiding the area where ammonia reacts with SO2 under the condition of water vapor in a high-sulfur environment.

[0030] Particularly in the present invention, the two C4 cyclones 2, C3 cyclones 3, C2 cyclones 4 and C1 cyclones 5 are respectively arranged on both sides of the decomposition furnace 6. Multiple SCR spray guns 11 are respectively located on the straight sections of the C3 cyclones 3 and C4 cyclones 2. The SNCR spray guns 10 are located on the straight sections of the C5 cyclones 1. The gas analyzer 12 is located at the inlet, outlet of the decomposition furnace 6 and the outlet of the C1 cyclone 5. The intelligent prediction and distribution module 13 synchronously collects the temperature of the decomposition furnace 6 and the temperatures of the C5 cyclone 1, C4 cyclone 2, C3 cyclone 3, C2 cyclone 4, C1 cyclone 5, and the data of the coal consumption at the kiln tail. The number of each group of SNCR spray guns 10 is two.

[0031] The present invention also proposes an SCR coupled with SNCR denitration working method in a high-sulfur environment, including the following steps:

[0032] S1: Acquisition and analysis, the gas analyzer 12 is used to collect the flue gas at the inlet, outlet of the decomposition furnace 6 and the outlet of the C1 cyclone 5 in real time, and analyze the SO2 and NO therein Xand the O2 content, and transmit the data to the intelligent prediction and distribution module 13;

[0033] S2: Predict the concentration. The intelligent prediction and distribution system 13 predicts the NOx and SO2 concentrations of each subsequent cyclone based on the real-time data of the gas analyzer 12, combined with the temperature of the decomposition furnace 6 and the temperatures of the C5 cyclone 1, C4 cyclone 2, C3 cyclone 3, C2 cyclone 4, C1 cyclone 5, and the parameter of the coal consumption at the kiln tail;

[0034] S3: Intelligent distribution. The intelligent prediction and distribution module 13 automatically distributes ammonia water to the SCR ammonia injection module 8 and the SNCR ammonia injection module 9 according to the predicted data in S2, and at the same time distributes different ammonia water dosages to the SCR spray guns 11 on the C4 cyclone 2 and the C3 cyclone 3;

[0035] S4: Real-time adjustment. By real-time adjusting the ammonia water dosages of the SCR spray guns 11 on the C4 cyclone 2 and the C3 cyclone 3, when the outlet emission index meets the requirements, gradually reduce the ammonia water dosage of the SNCR spray gun 10 until dynamic balance. Utilize the intelligent prediction and distribution module to predict and adjust the ammonia water dosages of the SCR spray guns corresponding to the C4 and C3 cyclones according to the real-time data of the gas analyzer, and gradually reduce the SNCR ammonia water dosage, giving full play to the high SCR denitrification efficiency, saving the total ammonia water dosage, reducing the production cost, and achieving ammonia slip control and ultra-low emissions.

[0036] Embodiment 2

[0037] Refer to Figure 1 - Figure 2, A SCR coupled with SNCR denitration system in a high-sulfur environment, comprising two C5 cyclones 1, two C4 cyclones 2, two C3 cyclones 3, two C2 cyclones 4, two C1 cyclones 5, a decomposition furnace 6, an SCR reactor 7, an SCR ammonia injection module 8, an SNCR ammonia injection module 9, two groups of SNCR spray guns 10, multiple SCR spray guns 11, a gas analyzer 12 and an intelligent prediction and distribution module 13. The two C5 cyclones 1 are respectively arranged on both sides of the decomposition furnace 6, and the decomposition furnace 6 is connected to the two C5 cyclones 1 through air ducts. The adjacent C5 cyclone 1, C4 cyclone 2, C3 cyclone 3, C2 cyclone 4 and C1 cyclone 5 are interconnected through air ducts. The outlets of the two C1 cyclones 5 are interconnected with the SCR reactor 7 through a three-way air duct. Multiple SCR spray guns 11 are respectively arranged on the outlet pipes of the two C3 cyclones 3 and the outlet pipes of the two C4 cyclones 2. The SCR ammonia injection module 8 is connected to the SCR spray guns 11 through a pipeline. The two groups of SNCR spray guns 10 are respectively arranged on the two C5 cyclones 1. The SNCR module 9 is connected to the SNCR spray guns 10 through a pipeline. The gas analyzer 12 is arranged on the three-way pipe at the outlets of the decomposition furnace 6 and the two C1 cyclones 5. The intelligent prediction and distribution module 13 is connected to the SCR ammonia injection module 8 and the SNCR ammonia injection module 9 through electrical signals. According to the reaction mechanism of SO2 and ammonia water, in a high-sulfur environment, by avoiding the temperature range where a large amount of SO2 is released, ammonia is injected at the C4 and C3 cyclones above 600 °C. Utilizing the time difference between the evaporation of ammonia and water and the regional concentration difference, the reaction between ammonia and SO2 is avoided. The ammonia gas enters the SCR reactor and undergoes a denitration reaction under the action of a catalyst, solving the problem of avoiding the region where ammonia reacts with SO2 under water vapor conditions in a high-sulfur environment.

[0038] Particularly in the present invention, the two C4 cyclones 2, C3 cyclones 3, C2 cyclones 4 and C1 cyclones 5 are respectively arranged on both sides of the decomposition furnace 6. Multiple SCR spray guns 11 are respectively located on the conical sections of the C3 cyclones 3 and C4 cyclones 2. The SNCR spray guns 10 are located on the conical section of the C5 cyclone 1. The gas analyzer 12 is located at the inlet, outlet of the decomposition furnace 6 and the outlet of the C1 cyclone 5. The intelligent prediction and distribution module 13 synchronously collects the temperature of the decomposition furnace 6 and the temperatures of the C5 cyclone 1, C4 cyclone 2, C3 cyclone 3, C2 cyclone 4, C1 cyclone 5, and the coal consumption data at the kiln tail. The number of each group of SNCR spray guns 10 is two or more.

[0039] The present invention also proposes a working method for SCR coupled with SNCR denitration in a high-sulfur environment, comprising the following steps:

[0040] S1: Acquisition and analysis, the gas analyzer 12 is used to collect the flue gas at the inlet, outlet of the decomposition furnace 6 and the outlet of the C1 cyclone 5 in real time, and analyze the SO2 and NO therein Xand the O2 content, and transmit the data to the intelligent prediction and distribution module 13;

[0041] S2: Predict the concentration. The intelligent prediction and distribution system 13 predicts the NOx and SO2 concentrations of each subsequent cyclone based on the real-time data of the gas analyzer 12, combined with the temperature of the decomposition furnace 6 and the temperatures of the C5 cyclone 1, C4 cyclone 2, C3 cyclone 3, C2 cyclone 4, C1 cyclone 5, and the parameter of the coal consumption at the kiln tail.

[0042] S3: Intelligent distribution. The intelligent prediction and distribution module 13 automatically distributes ammonia water to the SCR ammonia injection module 8 and the SNCR ammonia injection module 9 according to the predicted data in S2, and at the same time distributes different ammonia water dosages to the SCR spray guns 11 on the C4 cyclone 2 and the C3 cyclone 3.

[0043] S4: Real-time adjustment. By real-time adjusting the ammonia water dosage of the SCR spray guns 11 on the C4 cyclone 2 and the C3 cyclone 3, when the outlet emission index meets the requirements, gradually reduce the ammonia water dosage of the SNCR spray gun 10 until dynamic balance. Use the intelligent prediction and distribution module to predict and adjust the ammonia water dosage of the SCR spray guns corresponding to the C4 and C3 cyclones according to the real-time data of the gas analyzer, and gradually reduce the SNCR ammonia water dosage, giving full play to the high SCR denitrification efficiency, saving the total ammonia water dosage, reducing the production cost, and achieving ammonia slip control and ultra-low emissions.

[0044] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution of the present invention and its inventive concept, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. An SCR coupled SNCR denitration system in a high sulfur environment, characterized in that: The invention comprises two C5 cyclones (1), two C4 cyclones (2), two C3 cyclones (3), two C2 cyclones (4), two C1 cyclones (5), a decomposition furnace (6), an SCR reactor (7), an SCR ammonia spraying module (8), an SNCR ammonia spraying module (9), two groups of SNCR spray guns (10), a plurality of SCR spray guns (11), a gas analyzer (12) and an intelligent prediction distribution module (13). The two C5 cyclones (1) are respectively arranged on both sides of the decomposition furnace (6), and the decomposition furnace (6) is connected to the two C5 cyclones (1) through an air duct. The adjacent C5 cyclones (1), C4 cyclones (2), C3 cyclones (3), C2 cyclones (4) and C1 cyclones (5) are connected to each other through an air duct. The outlets of the C1 cyclones (5) are interconnected with the SCR reactor (7) through three ventilation pipes, the plurality of SCR spray guns (11) are respectively arranged on the outlet pipes of the two C3 cyclones (3) and the outlet pipes of the two C4 cyclones (2), the SCR ammonia spray module (8) is connected to the SCR spray gun (11) through a pipe, the two groups of SNCR spray guns (10) are respectively arranged on the two C5 cyclones (1), the SNCR module (9) is connected to the SNCR spray gun (10) through a pipe, the gas analyzer (12) is arranged on the three-way pipes at the outlets of the decomposition furnace (6) and the two C1 cyclones (5), and the intelligent prediction and distribution module (13) is connected to the SCR ammonia spray module (8) and the SNCR ammonia spray module (9) through an electrical signal.

2. The SCR coupled SNCR denitration system in a high sulfur environment according to claim 1, characterized in that: The two C4 cyclones (2), the C3 cyclone (3), the C2 cyclone (2) and the C1 cyclone (5) are respectively arranged on both sides of the decomposition furnace (6).

3. The SCR coupled SNCR denitration system in a high sulfur environment according to claim 2, characterized in that: The plurality of SCR spray guns (11) are respectively located on the straight section or the conical section of the C3 cyclone (3) and the C4 cyclone (2) body.

4. The SCR coupled SNCR denitration system in a high sulfur environment according to claim 1, characterized in that: The SNCR spray gun (10) is located on the straight section or the conical section of the C5 cyclone (1) body.

5. The SCR coupled SNCR denitration system in a high sulfur environment according to claim 1, characterized in that: The gas analyzer (12) is located at the inlet and outlet of the decomposition furnace (6) and the outlet of the C1 cyclone (5).

6. The SCR coupled SNCR denitration system in a high sulfur environment according to claim 1, characterized in that: The intelligent prediction and allocation module (13) synchronously collects the temperature of the decomposition furnace (6) and the temperatures of the C5 cyclone (1), the C4 cyclone (2), the C3 cyclone (3), the C2 cyclone (2), the C1 cyclone (5), and the coal consumption data at the kiln tail.

7. The SCR coupled SNCR denitration system in a high sulfur environment according to claim 1, characterized in that: The number of the two groups of SNCR spray guns (10) is two or more.

8. A method for SCR-coupled SNCR denitration in a high sulfur environment, characterized in that: The following steps are involved: S1: Collection and analysis: The flue gas at the inlet and outlet of the decomposition furnace (6) and the outlet of the C1 cyclone (5) is collected in real time by a gas analyzer (12) to analyze the SO2, NO X and O2 content, and transmit the data to the intelligent prediction and allocation module (13); S2: Predicted concentration: the intelligent prediction and distribution system (13) predicts the concentration of NOx and SO2 in each subsequent cyclone according to the real-time data of the gas analyzer (12), combined with the temperature of the decomposition furnace (6) and the temperature of the C5 cyclone (1), C4 cyclone (2), C3 cyclone (3), C2 cyclone (2), C1 cyclone (5), and the parameters of the amount of coal used at the end of the kiln; S3: Intelligent distribution, the intelligent prediction distribution module (13) automatically distributes ammonia water to the SCR ammonia spray module (8) and the SNCR ammonia spray module (9) according to the data predicted in S2, and at the same time distributes different ammonia water dosages to the SCR spray guns (11) on the C4 cyclone (2) and the C3 cyclone (3); S4: Real-time adjustment, by real-time adjustment of the amount of ammonia water used by the SCR spray gun (11) on the C4 cyclone (2) and the C3 cyclone (3), when the outlet emission index meets the requirements, the amount of ammonia water used by the SNCR spray gun (10) is gradually reduced until a dynamic balance is achieved.

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