Cement kiln flue gas SCR denitration system
By setting up a mixing zone and a reaction zone with reverse flow in the flue gas duct, combined with a metal dispersion layer and heating wire, the problem of catalyst clogging is solved, achieving efficient flue gas denitrification treatment and convenient equipment maintenance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- JIANGSU PROVINCE LONGJIE ENVIRONMENT ENG CO LTD
- Filing Date
- 2025-02-25
- Publication Date
- 2026-04-10
AI Technical Summary
In existing flue gas denitrification processes, catalysts are prone to clogging, requiring manual cleaning and resulting in low operational efficiency.
A mixing zone and a reaction zone are set up in the flue gas flow channel, and a reverse flow design is adopted. A metal honeycomb porous dispersion layer is set at the top of the reaction zone. Combined with an ammonia injection grid, a mixer and a slow flow zone, the mixing efficiency of ammonia and flue gas is improved. The dust and ammonium sulfate are pre-dispersed and desorbed through the metal dispersion layer and resistance heating wire to reduce catalyst blockage.
It improves the mixing efficiency of flue gas and ammonia, reduces the concentration of solid particulate matter in local areas of flue gas, reduces catalyst blockage, and improves denitrification conversion efficiency and equipment maintenance convenience.
Smart Images
Figure CN224100391U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to the field of flue gas treatment especially relates to a cement kiln flue gas SCR denitration system. BACKGROUND
[0002] In the cement kiln flue gas treatment, the selective catalytic reduction technology (SCR) is generally used for the denitration treatment of flue gas, and the basic principle is that ammonia gas is mixed with flue gas first, and then ammonia water or urea reacts with nitrogen oxide under the action of a catalyst to convert into nitrogen and water vapor, thereby completing the denitration operation. However, the presence of dust particles, sulfur dioxide and alkali metals in the flue gas during the denitration treatment will cause the generation of ammonium salt on the one hand, and the deposition of dust particles in the small pores of the catalyst will hinder the arrival of NOx, NH3 and O2 at the active surface of the catalyst, causing the passivation of the catalyst and reducing the denitration efficiency. In the conventional denitration pipeline, the flue gas is directly introduced into the catalyst region, and the particle concentration in the middle of the flue gas is higher than that in other regions, so it is easy to cause the blockage of the middle region of the catalyst, and the operator needs to frequently perform the dust removal operation. SUMMARY
[0003] The technical problem to be solved by the utility model is that in the existing flue gas denitration treatment, the catalyst is prone to blockage, manual dust removal treatment is required, and the operation efficiency is low. The utility model provides a cement kiln flue gas SCR denitration system to solve the above problems.
[0004] The technical scheme adopted by the utility model to solve the technical problem is that a cement kiln flue gas SCR denitration system is provided, and a mixing zone and a reaction zone are sequentially arranged on a flue gas flow channel. The flue gas flow direction of the mixing zone is upward flow, and the flue gas flow direction of the reaction zone is downward flow. In the reaction zone, a dispersion layer is arranged at the top, and a plurality of catalyst layers are arranged below the dispersion layer. The dispersion layer is made of metal material and has a honeycomb type porous structure.
[0005] Further, the mixing zone comprises a vertical straight pipeline and an ammonia injection grid arranged in the straight pipeline. The straight pipeline has an equal cross-section structure, and the ammonia injection grid is connected with a spraying device.
[0006] Further, the mixing zone further comprises a flow mixer arranged above the ammonia injection grid.
[0007] Further, a buffer flow zone is arranged between the mixing zone and the reaction zone. The buffer flow zone comprises a buffer flow pipe, and the buffer flow pipe has a shape of an inverted conical horn. A flow guide plate is arranged on the side of the buffer flow pipe close to the mixing zone, and a flow regulation grid is arranged on the side of the buffer flow pipe close to the reaction zone. A transverse baffle is arranged on the top wall of the buffer flow pipe.
[0008] Further, the front end of the mixing area is provided with an import area, the import area comprises a transversely arranged import pipeline, the cross section of the import pipeline is gradually reduced near the mixing area, and a flow guide plate is arranged in the import pipeline.
[0009] Further, a soot blower is arranged above the dispersion layer, and an electric resistance heating wire is connected to the dispersion layer.
[0010] The cement kiln flue gas SCR denitration system has the advantages that: the reverse mixing area and reaction area are arranged, the mixing efficiency of flue gas and ammonia gas is improved, the dispersion layer made of metal is arranged to realize pre-dispersion of flue gas before the flue gas contacts the catalyst, the concentration of solid particles in the local area of flue gas is reduced, dust is pre-adsorbed, heating is cooperated, ammonium salt is decomposed in time, the occurrence of catalyst blockage in the subsequent process is slowed down, and the denitration conversion efficiency of the catalyst is improved. BRIEF DESCRIPTION OF DRAWINGS
[0011] The utility model is further explained below by combining with the drawings and examples.
[0012] Figure 1 is a structure schematic view of the cement kiln flue gas SCR denitration system of the utility model;
[0013] Figure 2 is Figure 1 the local enlarged view of A in the figure.
[0014] Fig. 1, mixing area, 2, reaction area, 3, dispersion layer, 4, catalyst layer, 5, straight pipeline, 6, ammonia injection grid, 7, injection device, 8, flow mixer, 9, slow flow area, 10, slow flow pipe, 11, flow guide plate, 12, rectifier grid, 13, transverse baffle, 14, import area, 15, import pipeline. DETAILED DESCRIPTION
[0015] The embodiments of the utility model are described in detail below, and the examples of the embodiments are shown in the drawings, wherein the same or similar reference signs represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are only used to explain the utility model and cannot be understood as the limitation of the utility model. On the contrary, the embodiments of the utility model include all changes, modifications and equivalents falling within the spirit and scope of the appended claims.
[0016] In the description of the utility model, it is understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential" are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the utility model and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the utility model.
[0017] In addition, the terms "first", "second", etc. are only for the purpose of description, and cannot be understood as indicating or implying relative importance. In the description of the utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected", "connected" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in the utility model can be understood according to the specific circumstances. In addition, in the description of the utility model, unless otherwise specified, the meaning of "multiple" is two or more.
[0018] Any process or method described in the flowchart or otherwise described herein can be understood as representing a module, a segment or a portion of code including one or more executable instructions for implementing specific logical functions or processes, and the scope of the preferred embodiments of the utility model includes additional implementations in which the functions can be performed in an order other than that shown or discussed, including in a substantially simultaneous manner or in a reverse order according to the functions involved, which should be understood by those skilled in the art to which the embodiments of the utility model belong.
[0019] As Figure 1 , Figure 2 shown, the utility model provides a kind of cement kiln flue gas SCR denitration system, mixing zone 1 and reaction zone 2 are sequentially arranged on flue gas flow channel, the flue gas flow direction of mixing zone 1 is upwards, the flue gas flow direction of reaction zone 2 is downwards;In the reaction zone 2, top end is provided with dispersion layer 3, multiple catalyst layers 4 are provided below the dispersion layer 3;The dispersion layer 3 is metal material, and structure is honeycomb type porous structure.
[0020] SCR denitration technology is to first spray ammonia or other suitable reducing agent into the upstream flue gas, and then convert NOx in the flue gas into nitrogen and water by using catalyst at a temperature of 200-450°C. In the technical solution, the mixing area 1 is the link for mixing ammonia and flue gas, and the reaction area 2 is the conversion reaction link under the action of the catalyst. In the mixing area 1, the flue gas flows upward, which can promote the full mixing of ammonia and flue gas, improve the gas-solid contact efficiency, improve the effect of the subsequent reduction reaction, and improve the denitration rate. The reaction area 2 is designed in a reverse manner, and the flue gas flows downward, which utilizes the gravity to promote the separation and sedimentation of solid dust, reduces the dust deposition, and reduces the direct impact of fly ash on the dispersion layer 3 and the catalyst layer 4.
[0021] The reaction area 2 adopts a design manner that the upper layer is the dispersion layer 3 and the lower layer is the catalyst layer 4. After reaching the reaction area 2, the flue gas first contacts the dispersion layer 3. The dispersion layer 3 has a honeycomb porous structure and has a certain dispersion and flow regulation effect, which can change the original state of the flue gas with concentrated dust in the middle and promote the uniform distribution of the solid dust content in the flue gas.
[0022] Meanwhile, the dispersion layer 3 is made of metal material, which can be steel, copper or other common metal materials or alloy materials. This material is different from the material of the catalyst layer 4 below. Due to the material characteristics, the denitration catalyst is easy to adsorb dust and cause dust accumulation and even blockage. However, due to the smooth surface and low roughness of the metal material of the dispersion layer 3, it has small adhesion to solid dust particles. The solid dust of the flue gas can be efficiently separated after encountering the dispersion layer 3, improving the dispersion efficiency. Moreover, the metal material dispersion layer 3 is more wear-resistant and can be efficiently cleaned by strong dust cleaning means when it is blocked, which is convenient to maintain.
[0023] In the dispersion layer 3, the airflow almost forms a static pressure area, and the solid dust particles are fully dispersed. After passing through the dispersion layer 3, the uniformly dispersed flue gas flows to the subsequent process, which changes the distribution state of the flue gas on the surface of the catalyst layer 4, reduces the plane concentration of the flue ash, and disperses the solid particles in the flue gas to occupy the position of the catalyst pores. When entering the catalyst layer 4, the flow rate is slowed down, the catalyst layer 4 can fully contact and react with the flue gas, and the catalyst layer 4 will not be blocked due to the high concentration in the local area.
[0024] The mixing area 1 comprises a vertical straight pipe 5 and an ammonia spraying grid 6 arranged in the straight pipe 5, the straight pipe 5 is of equal cross-section structure, and the ammonia spraying grid 6 is connected with a spraying device 7. The ammonia spraying grid 6 sprays ammonia uniformly to the flue gas, and the dynamic mixing of ammonia and flue gas is realized by flow rate control. The flue gas in the mixing area 1 flows upwards, and the straight pipe 5 of equal cross-section structure is adopted, so that the turbulent flow field of the flue gas in the mixing area 1 is formed, the mixing effect is improved in the turbulent state, the mixed gas is in uniform flow state, the dynamic mixing of ammonia and flue gas is realized, and the treatment effect of the subsequent reduction reaction is ensured.
[0025] The mixing area 1 further comprises a flow mixer 8 arranged above the ammonia spraying grid 6. The flow mixer 8 can adopt several flow guide structures, which can accelerate the diffusion of ammonia by turbulent disturbance, break the laminar flow state of the flue gas, and improve the mixing effect of ammonia and flue gas.
[0026] The mixing area 1 and the reaction area 2 are provided with a buffer flow area 9, the buffer flow area 9 comprises a buffer flow pipe 10, the buffer flow pipe 10 is in the shape of an inverted conical horn, a flow guide plate 11 is arranged at the side of the buffer flow pipe 10 close to the mixing area 1, a flow regulating grid 12 is arranged at the side of the buffer flow pipe 10 close to the reaction area 2, and a transverse baffle 13 is arranged at the top wall of the buffer flow pipe 10.
[0027] The flow speed of the flue gas is gradually reduced through the buffer flow pipe 10, the flow guide plate 11 and the flow regulating grid 12 cooperatively eliminate vortex and homogenize the flow distribution. The buffer flow pipe 10 is in the shape of an inverted conical horn, which can disperse the central flow impact of the flue gas and reduce the flow resistance, the flow regulating grid 12 uniformly divides and homogenizes the slow flue gas, and facilitates the reduction reaction in the reaction area 2. Because the flow directions of the flue gas in the mixing area 1 and the reaction area 2 are opposite, the buffer flow area 9 can realize slow speed and flue gas reversing. The transverse baffle 13 can also guide the transversely flowing flue gas to the downward flowing state, which is convenient for the flue gas flow in the reaction area 2.
[0028] The front end of the mixing area 1 is provided with an introduction area 14, the introduction area 14 comprises a transversely arranged introduction pipe 15, the cross-section of the introduction pipe 15 is gradually reduced at the side close to the mixing area 1, and the flow guide plate 11 is arranged in the introduction pipe 15.
[0029] The flow guide plate 11 arranged in the introduction pipe 15 is mostly designed in a spiral shape, the spiral flow can be generated by the tapered pipe cooperating with the flow guide plate 11, the initial state of the flue gas entering the mixing area 1 is adjusted, the initial flow speed of the flue gas is accelerated, and the disturbance effect of the mixing area 1 is enhanced. At the same time, the flow guide plate 11 pre-disperses the dust, and reduces the abrasion of the subsequent device by large particles.
[0030] The dispersing layer 3 is provided with a soot blower above it, and the dispersing layer 3 is connected with a resistance heating wire.
[0031] The temperature range of 200-210 DEG C is the best temperature range for the generation of ammonium sulfate, and the catalyst activity is low, and the dosage is large. SO3 in the flue gas reacts with NH3 to generate ammonium sulfate byproduct, which is easy to paste the catalyst, causes the catalyst to be inactivated, and the ammonium sulfate is sticky, and it is difficult to use the soot blower to blow off. The dispersing layer 3 is heated by the resistance heating wire, the surface temperature of the dispersing layer 3 can be adjusted regularly, the generated ammonium sulfate is inhibited and decomposed, the catalyst passivation problem is solved, the conversion efficiency of the catalyst is ensured, and the catalyst plugging is reduced.
[0032] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the terms does not necessarily mean the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.
[0033] Based on the above ideal embodiments according to the present application, through the above description, relevant personnel can make various changes and modifications without deviating from the technical concept of the present application. The technical scope of the present application is not limited to the contents of the specification, and the technical scope must be determined according to the scope of the claims.
Claims
1. A cement kiln flue gas SCR denitration system, characterized in that: A mixing area (1) and a reaction area (2) are arranged in sequence on a flue gas flow channel, the flue gas flows upward in the mixing area (1), and the flue gas flows downward in the reaction area (2); A dispersion layer (3) is arranged at the top end of the reaction area (2), and a plurality of catalyst layers (4) are arranged below the dispersion layer (3); the dispersion layer (3) is made of metal and has a honeycomb porous structure.
2. The cement kiln flue gas SCR denitration system according to claim 1, characterized in that: The mixing area (1) comprises a vertical straight pipe (5) and an ammonia injection grid (6) arranged in the straight pipe (5), the straight pipe (5) has an equal cross-section structure, and the ammonia injection grid (6) is connected with a spraying device (7).
3. The cement kiln flue gas SCR denitration system according to claim 2, characterized in that: The mixing area (1) further comprises a flow mixer (8) arranged above the ammonia injection grid (6).
4. The cement kiln flue gas SCR denitration system according to claim 3, characterized in that: A buffer area (9) is arranged between the mixing area (1) and the reaction area (2), the buffer area (9) comprises a buffer pipe (10), the buffer pipe (10) has a shape of an inverted conical horn, a flow guide plate (11) is arranged on the side of the buffer pipe (10) close to the mixing area (1), a flow regulation grid (12) is arranged on the side of the buffer pipe (10) close to the reaction area (2), and a transverse baffle (13) is arranged on the top wall of the buffer pipe (10).
5. The cement kiln flue gas SCR denitration system according to claim 4, characterized in that: A leading-in area (14) is arranged at the front end of the mixing area (1), the leading-in area (14) comprises a transversely arranged leading-in pipe (15), the cross-section of the leading-in pipe (15) gradually shrinks near the mixing area (1), and the leading-in pipe (15) is provided with a flow guide plate (11).
6. The cement kiln flue gas SCR denitration system according to claim 5, characterized in that: A soot blower is arranged above the dispersion layer (3), and the dispersion layer (3) is connected with an electric resistance heating wire.