Double-chamber linked scr flue gas denitration system

Abstract

The utility model provides a kind of SCR flue gas denitration system of double-chamber linkage, belong to flue gas denitration technical field, comprising: boiler, coal economizer, ammonia injection mixer, main reactor and auxiliary reactor, flue gas of boiler is sequentially discharged into coal economizer and ammonia injection mixer in pipeline, the inlet of ammonia injection mixer is also connected with the outlet of ammonia unit's pipeline mixer;The outlet of ammonia injection mixer is connected with the main reactor and auxiliary reactor connected in parallel respectively by pipeline;First electric stop valve is arranged on the inlet pipeline of main reactor, first electric regulating valve is arranged on the inlet pipeline of auxiliary reactor;Second electric regulating valve is arranged at the outlet of main reactor, second electric stop valve is arranged at the outlet of auxiliary reactor.The system can seamlessly switch or double-chamber collaborative operation to reactor by parallelly connected double-chamber, improve denitration efficiency, realize the purpose of no flow break, no denitration efficiency fluctuation, improve the stability and continuity of system operation.

Description

Technical Field

[0001] This utility model relates to the field of flue gas denitrification technology, and in particular to a dual-chamber SCR flue gas denitrification system. Background Technology

[0002] In recent years, environmental issues related to the coal gasification industry have received increasing attention. Among these, flue gas emissions, a major source of air pollution, have been a key focus of environmental research, with NOx emissions from coal combustion being a primary target for control. Over 95% of the NOx in coal-fired flue gas is in the form of NO, and of the remaining 5%, it is mainly NO2. NOx emitted into the atmosphere (including SOx) is a major contributor to acid rain. Besides acid rain, these acidic substances can also form "acid snow," "acid fog," and "acid frost" through snowfall, fog, and frost. Even in dry climates, these acidic substances can settle as dust and smoke, altering the pH of rivers, lakes, and seas, severely impacting the survival of flora and fauna and damaging ecosystems.

[0003] Among existing technologies, ammonia catalytic reduction is the most widely used. It produces no byproducts, does not cause secondary pollution, has a simple device structure, and boasts high removal efficiency (over 90%), reliable operation, and ease of maintenance. Selective catalytic reduction (SCR) is currently the most mature and reliable flue gas denitrification method in coal-fired power plants. It utilizes ammonia, carbon monoxide, or other reducing agents in the presence of a catalyst to reduce NOx in flue gas to nitrogen, water, or carbon dioxide, thereby removing NOx. However, current SCR flue gas denitrification systems generally operate with a single SCR reactor, which has significant limitations in performance, efficiency, and system safety. Furthermore, during normal coke oven production, if the SCR reactor malfunctions, it cannot promptly process nitrogen oxides in the coke oven flue gas, leading to substandard emissions, affecting normal coke oven production, and causing serious environmental pollution. Therefore, SCR flue gas denitrification systems require further improvement and refinement. Utility Model Content

[0004] This invention provides a dual-chamber SCR flue gas denitrification system with parallel dual chambers that can be seamlessly switched or operated in synergistic manner. This system improves denitrification efficiency, achieves the goal of no flow interruption and no denitrification efficiency fluctuation, and enhances the stability and continuity of system operation.

[0005] This utility model provides a dual-chamber linked SCR flue gas denitrification system, including: a boiler, an economizer, an ammonia injection mixer, a main reactor, and a secondary reactor. Flue gas from the boiler is sequentially discharged into the economizer and the ammonia injection mixer via pipelines. The inlet of the ammonia injection mixer is also connected to the outlet of the pipeline mixer in the ammonia unit. The outlet of the ammonia injection mixer is connected to the main reactor and the secondary reactor via pipelines. The ammonia unit includes an ammonia water storage tank, an ammonia stripping tower, and a pipeline mixer connected in sequence. The inlet of the pipeline mixer is also connected to the outlet of a blower. The main reactor and the secondary reactor are connected in parallel. A first electrically operated shut-off valve is installed on the inlet pipeline of the main reactor, and a first electrically operated regulating valve is installed on the inlet pipeline of the secondary reactor. The outlets of the main reactor and the secondary reactor are connected to a desulfurization system via pipelines. A second electrically operated regulating valve is installed at the outlet of the main reactor, and a second electrically operated shut-off valve is installed at the outlet of the secondary reactor.

[0006] Furthermore, the first electric shut-off valve, the first electric regulating valve, the second electric regulating valve, and the second electric shut-off valve are electrically connected to the controller.

[0007] Furthermore, an inlet flue with the same structure is provided between the first electric shut-off valve and the inlet of the main reactor, and between the first electric regulating valve and the inlet of the auxiliary reactor; the inlet flue has a tapered and gradually expanding structure.

[0008] Furthermore, multiple guide vanes are installed in the inlet flue, and these guide vanes are arranged parallel to each other along the flue gas flow direction; flue gas velocity measuring devices are also distributed between the inlet of the inlet flue and the guide vanes.

[0009] Furthermore, the surface of the guide plate is provided with a concave-convex flow disturbance structure; the concave-convex flow disturbance structure includes multiple strip-shaped protrusions, which are connected to each other to form alternating protrusions and depressions; the length direction of the strip-shaped protrusions is perpendicular to the flow direction of the flue gas.

[0010] Furthermore, the cross-sectional shape of the strip-shaped protrusion can be semi-circular, elliptical, triangular, trapezoidal, rectangular, or polygonal.

[0011] Furthermore, the cross-section of the strip-shaped protrusion is an isosceles triangle.

[0012] Furthermore, adjacent strip-shaped bumps have different heights, while spaced-out strip-shaped bumps have the same height, forming a "high-low-high" undulating structure on the surface of the guide plate.

[0013] Furthermore, the strip-shaped protrusions are symmetrically arranged on both the front and back sides of the guide plate, and the opposing strip-shaped protrusions on adjacent guide plates are staggered.

[0014] The dual-chamber SCR flue gas denitrification system provided by this utility model allows for seamless switching or coordinated operation of the reactors through parallel dual reactor chambers. These chambers operate independently, facilitating system maintenance, while also cooperating to improve denitrification efficiency, ensure NOx emission compliance, and prevent system shutdown due to single-equipment failure. It achieves the goal of uninterrupted flow and zero fluctuations in denitrification efficiency, meeting the flue gas volume requirements under various boiler load conditions. The system features a reasonable, efficient, and reliable structure, flexible operation, and strong operability, enhancing the stability, safety, and continuity of system operation, and has broad application prospects. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 A schematic diagram of the structure of a dual-chamber linked SCR flue gas denitrification system provided in one embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of the inlet flue provided in one embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of the guide plate provided in one embodiment of the present invention.

[0017] Explanation of reference numerals in the attached figures: 1. Boiler; 2. Economizer; 3. Ammonia injection mixer; 4. Main reactor; 5. Secondary reactor; 6. Pipeline mixer; 7. Ammonia storage tank; 8. Ammonia stripping tower; 9. Fan; 41. First electric shut-off valve; 42. Second electric regulating valve; 43. Inlet flue; 44. Baffle plate; 45. Flue gas velocity measuring device; 46. Strip-shaped protrusion; 51. First electric regulating valve; 52. Second electric shut-off valve. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions in the embodiments of this utility model are described clearly and completely below. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are also within the protection scope of this utility model.

[0019] like Figure 1This utility model discloses a dual-chamber SCR flue gas denitrification system, comprising: a boiler 1, an economizer 2, an ammonia injection mixer 3, a main reactor 4, and a secondary reactor 5. Flue gas from the boiler 1 is sequentially discharged into the economizer 2 and the ammonia injection mixer 3 via pipelines. The inlet of the ammonia injection mixer 3 is also connected to the outlet of the pipeline mixer 6 of the ammonia unit. The outlet of the ammonia injection mixer 3 is connected to the main reactor 4 and the secondary reactor 5 via pipelines. The ammonia unit includes an ammonia water storage tank 7, an ammonia stripping tower 8, and the pipeline mixer 6 connected in sequence. The inlet of the pipeline mixer 6 is also connected to the outlet of a blower 9. The main reactor 4 and the secondary reactor 5 are connected in parallel. A first electric shut-off valve 41 is installed on the inlet pipeline of the main reactor 4, and a first electric regulating valve 51 is installed on the inlet pipeline of the secondary reactor 5. The outlets of the main reactor 4 and the secondary reactor 5 are connected to a desulfurization system via pipelines. A second electric regulating valve 42 is installed at the outlet of the main reactor 4, and a second electric shut-off valve 52 is installed at the outlet of the secondary reactor 5.

[0020] After the denitrification system is operational, once the flue gas from boiler 1 reaches the preset temperature (e.g., ≥300℃), it is introduced into the system. After heat exchange in economizer 2, it is sent to ammonia injection mixer 3. Ammonia water in ammonia storage tank 7 of the ammonia unit is sent to ammonia stripping tower 8 for evaporation to form ammonia gas. The ammonia gas, along with air from fan 9 (or flue gas from the reactor outlet), enters pipeline mixer 6 for dilution and mixing, and then is sent to ammonia injection mixer 3 to mix evenly with the flue gas to be treated. The mixture then enters the main reactor 4 and / or auxiliary reactor 5, either individually or simultaneously. The flue gas vertically passes through the catalyst layer in the reaction chamber of the main reactor 4 and / or auxiliary reactor 5. Under the action of the catalyst, NOx in the flue gas reacts fully with the reducing agent (ammonia) to generate harmless N2 and H2O, achieving denitrification purification. The flue gas after denitrification is sent to the desulfurization system for further purification. The catalyst layers in the main reactor 4 and auxiliary reactor 5 can use commonly used catalysts in this field, such as V2O5 / WO3 / TiO2 catalysts, etc., without special restrictions.

[0021] The main reactor 4 and auxiliary reactor 5 can be seamlessly switched or operate in a dual-chamber coordinated manner. During operation, when the main reactor 4, which operates alone, requires maintenance (such as catalyst replacement) or experiences abnormalities (such as excessive flow rate or temperature), switching can be achieved via the electric regulating valves and electric shut-off valves on the reactor inlet and outlet pipes. This closes the main reactor 4 pipes and opens the auxiliary reactor 5 pipes. During the switching period, the flue gas continuously flows through the reaction chamber of the auxiliary reactor 5 without interruption, fluctuations in denitrification efficiency, or disruption to the normal operation of the denitrification system, ensuring continuous system operation. The switching steps from auxiliary reactor 5 to main reactor 4 are the same. Furthermore, when the overall flue gas treatment capacity of the system increases within a controllable range, such as when the flue gas volume exceeds the design load of a single reactor (e.g., ≥120%), the dual-chamber coordinated operation mode can be activated. Both the main and auxiliary reactors 5 simultaneously receive gas, sharing the denitrification load, improving denitrification efficiency, ensuring NOx emissions meet standards, and satisfying the requirements of high flue gas volume conditions. The system, with its parallel dual reactor chambers, allows for seamless switching or coordinated operation of the reactors, improving denitrification efficiency, avoiding system downtime due to single-equipment failure, achieving the goal of no flow interruption and no denitrification efficiency fluctuations, and enhancing the stability, safety, and continuity of system operation.

[0022] Preferably, the first electric shut-off valve 41, the first electric regulating valve 51, the second electric regulating valve 42, and the second electric shut-off valve 52 are electrically connected to the controller. The controller and its control program are common settings in the art and will not be described in detail here. The controller enables faster switching or coordinated operation control of the main and auxiliary reactors 5, improving the level of automation control of the system.

[0023] like Figure 1 Preferably, an inlet flue 43 with the same structure is provided between the first electric shut-off valve 41 and the inlet of the main reactor 4, and between the first electric regulating valve 51 and the inlet of the auxiliary reactor 5; the inlet flue 43 has a tapered and gradually expanding structure. The tapered and gradually expanding structure of the inlet flue 43 can guide the flue gas to gradually diffuse, initially reduce the flow rate and fluctuation of the flue gas, and ensure that the flue gas is evenly distributed in the reactor, thereby ensuring the stability of the catalyst layer and the full contact between the flue gas and the catalyst, which is beneficial to improving the denitrification effect.

[0024] like Figure 2Preferably, multiple guide vanes 44 are provided in the inlet flue 43, and the multiple guide vanes 44 are arranged parallel to each other along the flue gas flow direction; flue gas velocity measuring devices 45 are also distributed between the inlet of the inlet flue 43 and the guide vanes 44. The guide vanes 44 can make the flue gas evenly distributed in the inlet flue 43 and regulate the flow velocity distribution, thereby reducing local eddies and dead zones of flue gas in the reactor and reducing system resistance loss. The flue gas velocity measuring device 45 can be a Pitot tube, double Venturi velocimeter tube, backrest velocimeter tube, flute velocimeter tube, etc., which are commonly used in the field and are available on the market. The number can be one or more, which can be selected by technicians according to production conditions, and no special restrictions are imposed here.

[0025] like Figure 3 Preferably, the surface of the guide plate 44 is provided with a concave-convex turbulence structure; the concave-convex turbulence structure includes multiple strip-shaped protrusions 46, which are interconnected to form alternating protrusions and depressions; the length direction of the strip-shaped protrusions 46 is perpendicular to the flow direction of the flue gas. By providing a concave-convex turbulence structure on the surface of the guide plate 44, the vortex effect generated by the collision of the protrusions and depressions (i.e., grooves) with the flue gas is utilized to enhance the turbulence of the flue gas, significantly increasing the contact area and reaction sufficiency between the flue gas and the catalyst, and directly improving the denitrification efficiency.

[0026] Preferably, the cross-sectional shape of the strip-shaped protrusion 46 is semi-circular, elliptical, triangular, trapezoidal, rectangular, or polygonal.

[0027] Preferably, the cross-section of the strip-shaped protrusion 46 is an isosceles triangle.

[0028] like Figure 3 Preferably, adjacent strip-shaped protrusions 46 have different heights, while spaced-apart strip-shaped protrusions 46 have the same height, forming a "high-low-high" undulating structure on the surface of the guide plate 44. By using strip-shaped protrusions 46 of varying heights, the turbulence of the flue gas is further enhanced, changing the flow rate of the flue gas without increasing power consumption, thus improving the reaction rate while achieving energy saving and consumption reduction.

[0029] like Figure 3 Preferably, the strip-shaped protrusions 46 are symmetrically arranged on both sides of the guide plate 44, and the opposing strip-shaped protrusions 46 on adjacent guide plates 44 are staggered. The adjacent guide plates 44 are arranged in parallel with a certain gap, and the opposing strip-shaped protrusions 46 on adjacent guide plates 44 are staggered, so that a zigzag flue gas flow channel is formed between adjacent guide plates 44, which is beneficial to improving the uniformity of flue gas flow field distribution and promoting the stable operation of the flue gas denitrification reactor.

[0030] It should be noted that a rectifier plate, commonly used in the art, can also be installed behind the guide plate 44 to further ensure a uniform distribution of the flue gas velocity entering the SCR reactor. The guide plate 44 can also be equipped with an angle adjustment mechanism, commonly used in the art, and the rotation angle of the guide plate 44 can be controlled and adjusted by real-time monitoring of the flue gas velocity using the flue gas velocity measuring device 45, thereby precisely guiding the flue gas flow direction and ensuring its uniform distribution across the reactor cross-section. The above-mentioned mechanisms are all well-known technologies in the art; they are included here as extended examples, and the technical solutions included are also within the scope of protection of this utility model.

[0031] It should be noted that arrows without reference numerals indicate the flow direction of gas-liquid mixtures, gas phases, or liquid phases.

[0032] In the dual-chamber SCR flue gas denitrification system, flue gas from boiler 1 is heat-exchanged in economizer 2 and then sent to ammonia injection mixer 3. Ammonia water in ammonia storage tank 7 of the ammonia unit is sent to ammonia stripping tower 8 for evaporation to form ammonia gas. The ammonia gas, along with air from blower 9 (or flue gas from reactor outlet), enters pipeline mixer 6 for dilution and mixing, and then is sent to ammonia injection mixer 3 to mix evenly with the flue gas to be treated. The controller then opens the first electric shut-off valve 41 and the second electric regulating valve 42, while keeping the first electric regulating valve 51 and the second electric shut-off valve 52 closed, allowing the flue gas to enter the inlet flue duct 43. The flue gas gradually diffuses in the conical, gradually expanding inlet flue duct 43, and then passes through the guide plates 44 and the zigzag flue gas flow channels formed between adjacent guide plates 44, ensuring uniform distribution of the flue gas in the inlet flue duct 43 and initially reducing the flow rate and fluctuations of the flue gas, finally entering the main reactor 4. The flue gas passes vertically through the catalyst layer in the reaction chamber of the main reactor 4. Under the action of the catalyst, the NOx in the flue gas reacts fully with the reducing agent (ammonia) to generate harmless N2 and H2O, thus achieving denitrification and purification. The flue gas after denitrification is sent to the desulfurization system for the next step of purification.

[0033] When it is necessary to switch the denitrification to the auxiliary reactor 5, the controller opens the first electric regulating valve 51 and the second electric shut-off valve 52, and closes the first electric shut-off valve 41 and the second electric regulating valve 42, so that the flue gas enters the inlet flue 43 of the auxiliary reactor 5. After the flue gas undergoes flow rate and distribution adjustment in the inlet flue 43 and the guide plate 44 therein, it finally enters the auxiliary reactor 5 for denitrification reaction. After the denitrification is completed, the flue gas is sent to the desulfurization system for the next step of purification treatment.

[0034] When the overall flue gas treatment capacity of the system exceeds the design load of a single reactor (e.g., ≥120%), the controller will open the first electric shut-off valve 41, the first electric regulating valve 51, the second electric regulating valve 42, and the second electric shut-off valve 52. The main and auxiliary reactors 5 will simultaneously receive gas and share the denitrification load, thereby improving the denitrification efficiency, ensuring that NOx emissions meet the standards, and satisfying the requirements of high flue gas volume operation.

[0035] It should be noted that the detailed structure of some devices in this utility model is not described in detail, but belongs to the prior art known to those skilled in the art, and therefore will not be described again here. In addition, the parts of this device not described are the same as or can be implemented using existing technology.

[0036] It should be noted that those skilled in the art, under the guidance of this utility model, can also make some modifications to the design of the above system. For example, the equipment in the system is also equipped with level gauges, overflow / nitrogen pipelines, etc.; pumps, pressure sensors, flow meters or temperature sensors are installed on the conveying pipelines inside the system in different units or devices, and different valves, such as pressure relief valves, pressure regulating valves, safety valves, pneumatic valves, etc., are also installed to regulate and stabilize the pressure of the entire system, and the opening degree of the valves can also be adjusted to regulate the flow rate of materials in the pipeline, etc.

[0037] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it; although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

Claims

1. A dual-chamber SCR flue gas denitrification system, characterized in that, include: The system comprises a boiler, an economizer, an ammonia injection mixer, a main reactor, and a secondary reactor. Flue gas from the boiler is sequentially discharged into the economizer and the ammonia injection mixer via pipelines. The inlet of the ammonia injection mixer is also connected to the outlet of a pipeline mixer in the ammonia unit. The outlet of the ammonia injection mixer is connected to both the main reactor and the secondary reactor via pipelines. The ammonia unit includes an ammonia water storage tank, an ammonia stripping tower, and the pipeline mixer, all connected in sequence. The inlet of the pipeline mixer is also connected to the outlet of a blower. The main reactor and the auxiliary reactor are connected in parallel; a first electrically operated shut-off valve is installed on the inlet pipe of the main reactor, and a first electrically operated regulating valve is installed on the inlet pipe of the auxiliary reactor; the outlets of the main reactor and the auxiliary reactor are connected to the desulfurization system through pipelines, and a second electrically operated regulating valve is installed at the outlet of the main reactor, and a second electrically operated shut-off valve is installed at the outlet of the auxiliary reactor.

2. The dual-chamber linked SCR flue gas denitrification system according to claim 1, characterized in that, The first electric shut-off valve, the first electric regulating valve, the second electric regulating valve, and the second electric shut-off valve are each electrically connected to the controller.

3. The dual-chamber linked SCR flue gas denitrification system according to claim 1, characterized in that, An inlet flue with the same structure is provided between the first electric shut-off valve and the inlet of the main reactor, and between the first electric regulating valve and the inlet of the auxiliary reactor; the inlet flue has a tapered and gradually expanding structure.

4. The dual-chamber SCR flue gas denitrification system according to claim 3, characterized in that, The inlet flue is provided with multiple guide plates, which are arranged parallel to each other along the flue gas flow direction; a flue gas velocity measuring device is also distributed between the inlet of the inlet flue and the guide plates.

5. The dual-chamber linked SCR flue gas denitrification system according to claim 4, characterized in that, The surface of the guide plate is provided with a concave-convex flow disturbance structure; the concave-convex flow disturbance structure includes multiple strip-shaped protrusions, which are connected to each other to form alternating protrusions and depressions; the length direction of the strip-shaped protrusions is perpendicular to the flow direction of the flue gas.

6. The dual-chamber linked SCR flue gas denitrification system according to claim 5, characterized in that, The cross-sectional shape of the strip-shaped protrusion is semi-circular, elliptical, triangular, trapezoidal, rectangular, or polygonal.

7. The dual-chamber linked SCR flue gas denitrification system according to claim 5, characterized in that, The cross-section of the strip-shaped protrusion is an isosceles triangle.

8. The dual-chamber SCR flue gas denitrification system according to claim 5, characterized in that, The adjacent strip-shaped protrusions have different heights, while the spaced strip-shaped protrusions have the same height, forming a "high-low-high" undulating structure on the surface of the guide plate.

9. The dual-chamber SCR flue gas denitrification system according to claim 8, characterized in that, The strip-shaped protrusions are symmetrically arranged on both sides of the guide plate, and the opposite strip-shaped protrusions on adjacent guide plates are staggered.

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