Efficient SCR denitration system
By introducing pre-dust removal equipment, rectifiers, wire mesh and honeycomb catalysts into the SCR denitrification system, the problem of catalyst layer blockage is solved, the catalyst layer life is extended and the denitrification efficiency is improved.
Patent Information
- Application Number
- CN202420910228.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-04-26
- Publication Date
- 2024-12-20
- Estimated Expiration
- 2034-04-26
AI Technical Summary
The catalyst layer in the SCR reactor is easily blocked by the clogged fly ash in the dust, resulting in a decrease in denitrification efficiency and wear of the catalyst layer, which affects the service life.
A highly efficient SCR denitrification system was designed, including air preheater, pre-dust removal equipment, SCR reactor and ash delivery equipment. Through primary and secondary breaking technology, rectifier and wire mesh structure, combined with honeycomb denitrification catalyst and soot blower , to ensure effective filtration of dust in the flue gas and protection of the catalyst layer.
It effectively reduces the probability of blockage of the catalyst layer, extends the service life of the catalyst layer, improves denitrification efficiency and wear resistance, and ensures stable operation in high dust environments.
Smart Images
Figure CN222196514U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of flue gas treatment, in particular to a high-efficiency SCR denitration system. Background Art
[0002] SCR denitrification (Selective Catalytic Reduction, referred to as SCR) is the selective catalytic reduction denitrification technology, sometimes also known as ammonia catalytic reduction denitrification. It is to inject ammonia or other suitable reducing agents into the flue gas upstream of the catalyst, and use catalysts (alkali metals such as iron, vanadium, chromium, cobalt or molybdenum) to convert NOx in the flue gas into nitrogen and water at a temperature of 200-450°C.
[0003] For the SCR high ash stage process flue gas denitrification system, an air preheater is generally used to preheat the flue gas and an SCR reactor is used to catalyze the flue gas. The SCR reactor is generally arranged after the air preheater. It has been tested that the dust content of the flue gas at the outlet of the air preheater is as high as 70-85g / Nm 3 , which is a high-dust area. In particular, the agglomerated fly ash contained in the dust will often cause the catalyst layer in the SCR reactor to be blocked, seriously affecting the denitrification efficiency. Utility Model Content
[0004] The utility model provides a high-efficiency SCR denitration system, which can solve the problem that the catalyst layer in the SCR reactor is easily clogged by fly ash.
[0005] This application provides the following technical solutions:
[0006] A high-efficiency SCR denitration system comprises an air preheater, a pre-dust removal device, an SCR reactor, and an ash conveying device which are arranged in sequence along the flow direction of an airflow, the pre-dust removal device is connected to the ash conveying device at the same time, mesh grilles are installed between the pre-dust removal device and the ash conveying device and between the SCR reactor and the ash conveying device; a rectifier is arranged on the top of the SCR reactor, a catalyst layer is arranged in the SCR reactor, a wear-resistant layer is fixedly arranged on the top of the catalyst layer, and wire meshes are fixedly arranged between adjacent wear-resistant layers.
[0007] Beneficial effects:
[0008] 1. Pre-dust removal equipment is arranged between the air preheater and the SCR reactor to perform primary removal of the agglomerated fly ash in the flue gas flowing out of the air preheater and into the SCR reactor, ensuring that the dust content at the entrance of the SCR reactor is effectively controlled. This can not only avoid the blockage of the catalyst layer caused by the agglomerated fly ash contained in the dust, but also reduce the wear of the catalyst layer when the flue gas enters the catalyst layer by reducing the dust content of the flue gas, thereby increasing the service life of the catalyst layer, which is of great significance to the improvement of the denitrification efficiency.
[0009] 2. The mesh grille installed at the entrance of the SCR reactor and the rectifier installed on the top of the SCR reactor perform secondary removal of the agglomerated fly ash in the flue gas flowing out of the pre-dust removal equipment and flowing to the SCR reactor, thereby reducing the probability of clogging of the catalyst layer.
[0010] 3. Fixedly setting a wear-resistant layer on the top of the catalyst layer and fixedly setting a wire mesh between adjacent wear-resistant layers are important designs for improving the service life of the catalyst layer; the setting of the wire mesh with fine through holes also has a rectifying effect on the flue gas, so that the dusty flue gas can pass through the pores in the catalyst layer evenly, reducing the scouring of the inner wall of the catalyst layer and improving the wear resistance; it is worth mentioning that the agglomerated fly ash after secondary breaking may form large agglomerates of particles, and the wire mesh also has the function of intercepting large agglomerates of particles; the role of the wear-resistant layer is to prevent large agglomerates of particles from directly acting on the surface of the catalyst layer, reduce the wear of the catalyst layer and improve the service life of the catalyst layer; this solution significantly improves the catalyst layer's ability to cope with harsh working conditions with high dust scouring, and meets the requirements for the service life of the catalyst layer.
[0011] Furthermore, as an improvement, an air outlet is provided on the SCR reactor corresponding to the upper edge of the wire mesh, and a soot blower is provided to be connected to the air outlet.
[0012] Beneficial effect: The compressed air sprayed by the soot blower will gradually blow away the large particles trapped on the wire mesh until it is blown clean, further reducing the probability of clogging of the catalyst layer.
[0013] Furthermore, as an improvement, the rectifier is a grid rectifier.
[0014] Beneficial effects: The grid-shaped rectifier has a simple structure and can perform secondary removal of agglomerated fly ash in the flue gas while ensuring a good rectification effect on the flue gas.
[0015] Furthermore, as an improvement, the catalyst layer uses a honeycomb denitration catalyst, including a plurality of honeycomb holes, and the inner wall thickness of the honeycomb holes is ≥1.5 mm.
[0016] Beneficial effects: Honeycomb denitrification catalysts have obvious advantages over other types of denitrification technologies, mainly reflected in the fact that honeycomb denitrification catalysts can efficiently convert NOx in flue gas into harmless nitrogen and water vapor in the catalytic reaction, with high removal efficiency and low investment and operation and maintenance costs. Generally speaking, the inner wall thickness of the honeycomb holes on the honeycomb denitrification catalysts is less than 1mm. This solution can effectively improve the wear resistance of the catalyst product by increasing the inner wall thickness while ensuring excellent flue gas pass rate, thereby further improving the service life of the catalyst product.
[0017] Further, as an improvement, a reducer is installed at the inlet of the SCR reactor, and the mesh grille is fixedly arranged in the reducer.
[0018] Beneficial effect: Compared with the solution of directly installing the mesh grille in the flue gas conveying pipe, the mesh grille is arranged in the reducer, which provides convenient conditions for the installation of the mesh grille. The reducer itself as a pipe connecting device also helps to connect the SCR reactor and the pre-dust removal equipment.
[0019] Furthermore, as an improvement, a boss is provided on the top of the catalyst layer, and a groove matching with the boss is provided at the bottom of the wear-resistant layer.
[0020] Beneficial effect: The wear-resistant layer is fixedly arranged on the catalyst layer through the cooperation of the boss on the catalyst layer and the groove on the wear-resistant layer.
[0021] Further, as an improvement, the honeycomb denitration catalyst is composed of several honeycomb modules, and through grooves and protrusions are respectively provided on both sides of each honeycomb module. The through grooves and protrusions on adjacent honeycomb modules constitute a connecting component for fixedly connecting adjacent honeycomb modules.
[0022] Beneficial effect: The honeycomb modules are spliced together through the connecting components consisting of the through grooves and protrusions on the adjacent honeycomb modules. The modular structure makes the catalyst layer more versatile and can be adjusted arbitrarily according to project needs.
[0023] Further, as an improvement, the protrusion is arranged in the middle position of the side wall so that after the protrusion is inserted into the through groove, a partial gap remains above the protrusion, and a convex strip is arranged at the bottom of the wear-resistant layer so as to be inserted into the gap.
[0024] Beneficial effect: After the protrusion is inserted into the through groove, a part of the gap is left above the protrusion, which reserves a connection position for fixing the wear-resistant layer on the catalyst layer. Specifically, a convex strip is provided at the bottom of the wear-resistant layer, which can be inserted into the gap to achieve fixation. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Figure 1 This is a schematic structural diagram of a first embodiment of a high-efficiency SCR denitration system of the utility model;
[0026] Figure 2 for Figure 1 The enlarged schematic diagram of point A in the middle;
[0027] Figure 3 for Figure 2 Schematic diagram of the structure of the middle mesh grille;
[0028] Figure 4 for Figure 1 A cross-sectional view of the first catalyst portion;
[0029] Figure 5 For comparative example 1 Figure 4 A cross-sectional view of
[0030] Figure 6 for Figure 5 The enlarged schematic diagram of point B in the middle;
[0031] Figure 7 It is a top view of the catalyst layer in the second embodiment of the present utility model;
[0032] Figure 8 for Figure 7 CC section view in;
[0033] Fig. 9 For the corresponding Figure 8 Cross-sectional view of the installation of a wear-resistant layer on the catalyst layer. DETAILED DESCRIPTION
[0034] The following is further described in detail through specific implementation methods:
[0035] The marks in the drawings of the specification include: air preheater outlet 1, pre-dust removal equipment 2, SCR reactor 3, reactor shell 31, air outlet 311, rectifier 32, first catalyst 33, inner wall 331, honeycomb holes 332, boss 333, wear-resistant layer 334, convex strip 334a, wire mesh 335, second catalyst 34, ash conveying equipment inlet 4, reducer 5, mesh grille 51, large particles 6, dust 7, honeycomb module 8, through groove 81, gap 811, protrusion 82.
[0036] Embodiment 1
[0037] Combination Figure 1-Figure 6 As shown, a high-efficiency SCR denitrification system includes an air preheater outlet 1, a pre-dust removal device 2, and an SCR reactor 3 arranged in sequence along the air flow direction; the pre-dust removal device 2 and the SCR reactor 3 are respectively connected to ash conveying equipment, specifically connected to the ash conveying equipment inlet 4, the function of the ash conveying equipment is to recycle the agglomerated fly ash and dust 7 and other wastes collected by the pre-dust removal device 2 and the SCR reactor, and the SCR reactor 3 includes a reactor shell 31 and a catalyst layer fixedly arranged in the reactor shell 31.
[0038] The pre-dust removal device 2 uses an electrostatic precipitator with a dust removal efficiency of not less than 50%. The electrostatic precipitator is used to break up the agglomerated fly ash hidden in the flue gas at the first level. The pre-dust removal device 2 is connected to the air preheater outlet 1, the reactor shell 31 inlet, and the ash conveying device through pipelines, wherein the two ends of the pipeline between the pre-dust removal device 2 and the reactor shell 31 are respectively connected to the outlet of the pre-dust removal device 2 and the small end of the reducer 5 installed at the inlet of the reactor shell 31, and the large end of the reducer 5 is connected to the inlet of the SCR reactor 3. A mesh grille 51 is fixedly arranged in the small end and the large end of the reducer 5. The structure of the mesh grille 51 is as shown in FIG. Figure 3 As shown, it is a steel structure with several rectangular channels arranged crosswise in the middle. When the agglomerated fly ash passes through the rectangular channels, it will undergo secondary breaking and eventually form fine ash and enter the SCR reactor 3.
[0039] A grid-shaped rectifier 32 is fixedly installed on the upper layer of the catalyst in the SCR reactor shell 31 . The rectifier 32 not only rectifies the flue gas to make the flow field distribution more uniform, but also has the same function of breaking up the agglomerated fly ash as the mesh grid 51 .
[0040] The catalyst layer includes a first catalyst 33 located at the top and a second catalyst 34 located at the bottom, which are arranged in sequence. In other embodiments, the number of catalyst layers can be adaptively adjusted. Taking the first catalyst 33 as an example, the first catalyst 33 uses a 10*10 honeycomb denitration catalyst, including a plurality of honeycomb holes 332 surrounded by an inner wall 331. In this embodiment, the thickness C of the inner wall 331 is selected to be 1.5 mm. A boss 333 is arranged on the top of the first catalyst 33. A wear-resistant layer 334 is fixedly arranged on the top of the first catalyst 33. The wear-resistant layer 334 has the same honeycomb structure as the catalyst layer. The wear-resistant layer 334 is made of a high-hardness metal alloy. 4 is provided with a groove matched with the boss 333 to fix the wear-resistant layer 334 on the first catalyst 33, and a wire mesh 335 is welded and fixed between two adjacent wear-resistant layers 334. The wire mesh 335 has a plurality of small and precisely distributed holes in the middle. The wire mesh 335 is provided to intercept the large agglomerates 6 remaining in the fine ash on the wire mesh 335. An air port 311 is provided on the reactor shell 31 at the upper edge position corresponding to the wire mesh 335, and a rake soot blower is provided to communicate with the air port 311. The compressed air blown out by the rake soot blower can disperse the large agglomerates 6 into fine particles so as to fall into the honeycomb holes 332 in the catalyst layer.
[0041] The specific application process is as follows:
[0042] When in use, the flue gas from the air preheater outlet 1 first flows into the pre-dust removal device 2 to remove the agglomerated fly ash hidden in the flue gas. The sieved dust 7 is connected to the ash conveying device inlet 4 through a pipeline from the bottom for collection. Then the flue gas passes through Figure 1 As shown, the pipeline located on the right side of the pre-dust removal device 2 flows into the SCR reactor 3. It is worth mentioning that the mesh grille 51 installed in the reducer 5 and the rectifier 32 installed in the reactor shell 31 will perform secondary decomposition of the agglomerated fly ash remaining in the flue gas to form large agglomerates or fine particles that fall into the first catalyst 33, as shown in FIG. Figure 4 As shown, the fine particles falling onto the wear-resistant layer 334 will also fall into the honeycomb holes 332 in the first catalyst 33 through the holes in the wire mesh 335 under the action of the vertically downward flue gas flow, while the large particles 6 will be intercepted outside the wire mesh 335, and the compressed air generated by the rake soot blower connected to the air outlet 311 will blow the large particles 6 away to eventually form a number of fine particles, namely dust 7. Finally, the dust 7 that is sieved out is also connected to the inlet 4 of the ash conveying equipment through a pipeline from the bottom of the SCR reactor 3 for collection and centralized treatment.
[0043] Compared with the existing technology, this solution can effectively increase the service life of the catalyst layer by providing a two-stage structure for breaking up agglomerated fly ash and a protective structure on the catalyst layer, which has an important and positive significance for improving the denitrification efficiency.
[0044] Embodiment 2
[0045] Compared with the first embodiment, this embodiment Figure 7-Figure 9 As shown, the difference lies in the specific structure of the catalyst layer. The catalyst layer still uses a honeycomb denitration catalyst, which is composed of a plurality of honeycomb modules 8. Figure 7 What is shown is that four honeycomb modules 8 are spliced together, each honeycomb module 8 is provided with a through groove 81 and a protrusion 82, and the through grooves 81 and protrusions 82 on adjacent honeycomb modules 8 constitute a connecting component. It is worth noting that Figure 8 The through groove 81 on the honeycomb module 8 is a through groove arranged on the side wall, and the protrusion 82 is arranged in the middle position of the side wall. Fig. 9 As shown, after the protrusion 82 is inserted into the through groove 81, a partial gap 811 is left above the protrusion 82. The wear-resistant layer 334 and the catalyst layer also have a honeycomb structure. A convex strip 334a is provided at the bottom of the wear-resistant layer 334. The convex strip 334a can be inserted into the above-mentioned gap 811 and the through groove 81 on the honeycomb module 8 at the edge position of the catalyst layer where the protrusion 82 is not inserted.
[0046] In this embodiment, if Fig. 9 As shown, the wire mesh 335 adopts a whole piece structure and is sandwiched between the wear-resistant layer 334 and the catalyst layer. A through hole is opened on the wire mesh 335 at the position corresponding to the gap 811, so that the protrusion 334a can be smoothly inserted into the gap 811, and at the same time, it can also fix the wire mesh 335.
[0047] Comparative Example 1
[0048] Compared with Example 1, the difference between this comparative example and Example 1 is that Figure 5 As shown, the wire mesh 335 is an integral structure and is laid on the wear-resistant layer 334 as a whole. Compared with the first embodiment, the fine particles formed by the large particles 6 being blown away are easily stuck in the wear-resistant layer 334. Figure 6 The wire mesh 335 corresponding to the top of the wear-resistant layer 334 shown in the figure makes it impossible for the compressed air to act on the fine particles, which brings inconvenience to the removal of the fine particles.
[0049] The above is only an embodiment of the utility model. The utility model is not limited to the field involved in this implementation case. The common knowledge such as the known specific structure and characteristics in the scheme is not described in detail here. It should be pointed out that for those skilled in the art, several deformations and improvements can be made without departing from the structure of the utility model, which should also be regarded as the protection scope of the utility model, and these will not affect the effect of the implementation of the utility model and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.
Claims
1. A high-efficiency SCR denitration system, characterized by: It includes an air preheater, a pre-dust removal device, an SCR reactor, and an ash conveying device which are arranged in sequence along the air flow direction. The pre-dust removal device is connected to the ash conveying device at the same time, and a mesh grille is installed at the entrance of the SCR reactor; A rectifier is arranged on the top of the SCR reactor, a catalyst layer is arranged in the SCR reactor, a wear-resistant layer is fixedly arranged on the top of the catalyst layer, and a wire mesh is fixedly arranged between adjacent wear-resistant layers or is arranged below the wear-resistant layer.
2. A high-efficiency SCR denitration system according to claim 1, characterized in that: An air outlet is opened on the SCR reactor corresponding to the upper edge of the wire mesh, and a soot blower is arranged to be connected to the air outlet.
3. A high-efficiency SCR denitration system according to claim 2, characterized in that: The rectifier is a grid rectifier.
4. A high-efficiency SCR denitration system according to claim 3, characterized in that: The catalyst layer uses a honeycomb denitration catalyst, which includes a plurality of honeycomb holes, and the inner wall thickness of the honeycomb holes is ≥1.5mm.
5. A high-efficiency SCR denitration system according to claim 4, characterized in that: A reducer is installed at the inlet of the SCR reactor, and the mesh grille is fixedly arranged in the reducer.
6. A high-efficiency SCR denitration system according to claim 5, characterized in that: A boss is arranged on the top of the catalyst layer, and a groove matching with the boss is arranged at the bottom of the wear-resistant layer.
7. The high-efficiency SCR denitration system according to claim 5, characterized in that: The honeycomb denitration catalyst is composed of a plurality of honeycomb modules. Through grooves and protrusions are respectively arranged on both sides of each honeycomb module. The through grooves and protrusions on adjacent honeycomb modules form a connecting assembly for fixedly connecting adjacent honeycomb modules.
8. The high-efficiency SCR denitration system according to claim 7, characterized in that: The protrusion is arranged at the middle position of the side wall so that a part of the gap is left above the protrusion after the protrusion is inserted into the through groove, and the convex strip arranged at the bottom of the wear-resistant layer can be inserted into the gap.