CN114653360A

CN114653360A - Novel catalyst suitable for SCR denitration of cement kiln

Info

Publication number: CN114653360A
Application number: CN202210430870.7A
Authority: CN
Inventors: 钱付平; 高艺华; 孙婉莹; 孙祎; 吴胜华; 吴越
Original assignee: Anhui University of Technology AHUT
Current assignee: Anhui University of Technology AHUT
Priority date: 2022-04-22
Filing date: 2022-04-22
Publication date: 2022-06-24

Abstract

The invention relates to the technical field of catalysts, in particular to a novel catalyst suitable for SCR denitration of a cement kiln, which comprises a cuboid catalyst unit body used for bearing active ingredients of the catalyst, wherein catalyst through holes are arranged in the catalyst unit, the catalyst through holes are arranged in an array manner and in the catalyst unit, the catalyst through holes are arranged in a lamination manner, the cross sections of the catalyst through holes in odd layers are regular hexagons, the cross sections of the catalyst through holes in even layers are regular triangles, and the catalyst through holes in all layers are staggered.

Description

Novel catalyst suitable for SCR denitration of cement kiln

Technical Field

The invention relates to the technical field of catalysts, and particularly relates to a novel catalyst suitable for SCR denitration of a cement kiln.

Background

Nitrogen Oxides (NO), a typical emission of the cement industry_X) Is one of the main pollution sources of atmospheric pollution. Domestic NO for cement industry_XThe control of (1) is more and more important, and the current industry executes the emission Standard of atmospheric pollutants for Cement industry (GB 4915-2013), wherein NO is_XThe emission standard is 400mg/Nm³Now, each province is on NO_XThe emission has higher requirements. Thus, realizing NO in cement industry_XUltralow emission is one of the important strategies for air pollution control.

Selective Catalytic Reduction (SCR) with the highest NO_XThe removal rate (90% to 95%) is considered to be the most practical post-treatment method. The catalyst is used as a core component of the SCR system, occupies about 50 percent of the investment of the whole denitration unit, and the chemical property, the stability and the service life of the catalyst can directly influence the denitration efficiency of the whole unit. The cement kiln flue gas has the characteristics of large air quantity, high temperature and large dust content, so that a catalyst of an SCR system of the cement kiln flue gas needs to have higher denitration efficiency, a wider reaction temperature window and stronger structural stability. The denitration catalysts on the market can be classified into three types: plate type, honeycomb type and corrugated plate type, and the honeycomb type catalyst with large pitch is preferably selected according to the comprehensive consideration of high dust characteristic of flue gas of a cement kiln, engineering operation stability, investment risk and the like. Therefore, the research and the design of a novel catalyst for denitration in the cement industry are key steps for improving the traditional process and exploring the catalytic removal of nitrogen oxides.

In view of the above-mentioned drawbacks, the inventors of the present invention have finally obtained the present invention through a long period of research and practice.

Disclosure of Invention

The invention aims to solve the problem that the existing catalyst cannot meet the requirements of an SCR system on high denitration efficiency, a wide reaction temperature window and strong structural stability, and provides a novel catalyst suitable for SCR denitration of a cement kiln.

In order to achieve the purpose, the invention discloses a novel catalyst suitable for SCR denitration of a cement kiln, which comprises a cuboid catalyst unit body used for bearing active ingredients of the catalyst, wherein catalyst through holes are arranged in the catalyst unit, the catalyst through holes are arranged in the catalyst unit in an array mode and in the catalyst unit in a laminated mode, the cross sections of the catalyst through holes in the odd layers are regular hexagons, the cross sections of the catalyst through holes in the even layers are regular triangles, and the catalyst through holes in all layers are arranged in a staggered mode.

And the size and the shape of each layer of through holes of the catalyst through holes are consistent.

The length of the catalyst through hole is 200mm, the number of laminated layers is 4-6, and the height of the catalyst unit is 800-1200 mm.

The side length of the catalyst through hole with the cross section being a regular hexagon is 10-20 mm, and the side length of the catalyst through hole with the cross section being a regular triangle is the same as that of the catalyst through hole with the cross section being a regular hexagon.

The number of the catalyst unit holes is 13, the thickness of the inner wall is 1.5mm, the thickness of the outer wall is 2.3mm, and the opening rate is 0.723.

The boundary of each catalyst through hole with the cross section of a regular hexagon is superposed with the projection position of the boundary of every six catalyst through holes with the cross sections of a regular triangle of the adjacent layer.

The catalyst is prepared by adopting an impregnation drying method and taking an organic vanadium compound as a vanadium precursor and titanium dioxide, titanium tungsten powder or titanium molybdenum powder as a carrier.

The active component of the catalyst is vanadium pentoxide, and the cocatalyst is tungsten oxide.

Compared with the prior art, the invention has the beneficial effects that: according to the invention, the active component is loaded in the catalyst carrier through a dipping and drying process, and the nitrogen oxide can be removed under the action of the catalyst when the flue gas containing pollutants passes through the catalyst, so that the flue gas denitration is realized. The catalyst laminated assembly structure used by the invention provides a higher specific surface area for gas-solid catalytic reaction, overcomes the defects that the smaller the size of the through hole is, the higher the removal efficiency is but the production cost is high in the existing research, is suitable for the catalytic requirements of high-dust processes of cement kilns and the like, and realizes the high efficiency of flue gas purification on the basis of the balance of difficult blockage of the larger catalyst through hole and high catalytic efficiency of the larger specific surface area.

The novel catalyst suitable for cement kiln flue gas denitration provided by the invention overcomes the pain of denitration efficiency reduction caused by adopting a top end hardening measure and cost increase caused by increasing the thickness of the catalyst wall in the traditional SCR catalyst, improves the flue gas treatment and purification efficiency, has long service life, reduces the production investment cost, and realizes energy conservation and consumption reduction.

Drawings

FIG. 1 is a schematic diagram of the structure of a catalyst unit according to the present invention;

FIG. 2 is a schematic view of a catalyst via stack according to the present invention;

FIG. 3 is a graph of the effect of temperature on the denitration efficiency of different types of catalysts;

FIG. 4 shows a comparison of the wear rates of different types of catalysts.

The figures in the drawings represent:

1-a catalyst unit; 2-catalyst through holes.

Detailed Description

The above and further features and advantages of the present invention are described in more detail below with reference to the accompanying drawings.

The embodiment provides a novel catalyst suitable for cement kiln flue gas denitration, as shown in fig. 1-2, including catalyst unit 1, its characterized in that: the catalyst unit 1 is assembled in a laminated manner, 4-6 layers of layers are laminated, the porosity of the wall surface of the catalyst is 42.3%, the thickness of the catalyst is 800-1200 mm, and the thickness of the outer wall of the catalyst is 2.3 mm; the catalyst through holes 2 are regular hexagons and regular triangles, the side length of each through hole is 10-20 mm, no matter how long the side length of each regular hexagon catalyst hole is, the side length of each regular triangle catalyst hole is consistent with that of each regular hexagon catalyst hole, the number of catalyst unit holes is 13, the thickness of the inner wall is 1.5mm, and the boundary of each regular hexagon catalyst through hole is superposed with the projection position of the boundary of every six regular triangle catalyst through holes of the adjacent layer. The advantage of this structure lies in, the stable structural performance of catalyst and excellent catalytic efficiency have been ensured to great aperture and the high specific surface area that honeycombed and triangle-shaped stromatolite equipment brought, accord with the high dust concentration SCR denitration demand of cement industry to because big aperture has lower filtration pressure drop, also reduced the consumption of energy simultaneously.

The flue gas passes through the surface of the catalyst at an incident angle of not more than 10 DEG and reaches a gas containing V₂O₅-WO₃/TiO₂The carrier of the catalyst, the catalyst in the carrier can efficiently and selectively catalyze and reduce the nitrogen oxide. The main chemical reaction formula of the flue gas passing through the catalyst is as follows:

4NO+4NH₃+O₂→4N₂+6H₂O

when the catalyst reaches or is close to the active life cycle, can change the comparatively serious catalyst layer of wearing and tearing can, increased the life of whole catalyst module promptly, can guarantee higher level catalysis denitration efficiency again. And finally, the denitrated clean flue gas flows out through the flue of the SCR reactor and is discharged from a chimney under the action of an induced draft fan.

According to the structural parameters of the specific embodiment, the denitration effect of the invention is simulated by combining with computational fluid dynamics commercial software ANSYS fluent. The numerical simulation conditions were: the catalyst in the preparation embodiment is used for evaluating the denitration performance of the flue gas of the cement kiln, the novel catalyst has 6 multiplied by 6-36 channels, the opening size of the channels is 6mm, the selected wall thickness is 1mm, and the length of the honeycomb catalyst is 50 mm. The porosity of the wall was 42.3%, and the average particle size in the porous medium was 1X 10^-6m, the coefficient of viscous drag calculated is 1.264 x 10¹⁵m^-2The inertial resistance coefficient was 502541 (1/m). The inlet speed is 0.017 m/s; the inlet temperature range is 513-593K; the components of the inlet smoke are 0.04 percent of NO and 0.05 percent of NH₃、5％O₂、8％H₂O, others are N₂. The test adopts 90-97% of dust with particle size less than l0 μm and 50% of dust with particle size less than 2-3 μm. The specifications and components of the catalyst of the comparison group with triangular, quadrangular and hexagonal through holes are consistent with the novel structure.

The denitration efficiency calculation method comprises the following steps:

η＝(C_in-C_out)×100％/C₁

wherein eta is denitration efficiency, C_inAnd C_outRespectively testing the concentration of NO at the inlet and the outlet of the catalyst in mg/Nm³。

The simulation results are shown in fig. 3. Due to the fact that the triangular through holes are formed, the contact area of the catalyst and the flue gas under the same specification is increased, and the denitration efficiency of the catalyst is higher than that of a common catalyst, as shown in figure 3. The wear rate of the catalyst in fig. 4 shows that the most worn area of the catalyst is the top end of the catalyst, but the average wear rate of the top end of the novel structure is the minimum, the average wear rate of the positions where Y is 10mm and Y is 20mm is slightly larger than that of the common catalyst, because the areas are triangular through hole areas, only the catalyst unit of the layer needs to be replaced when the catalyst is worn seriously, and the working time and the cost are saved.

The foregoing is merely a preferred embodiment of the invention, which is intended to be illustrative and not limiting. It will be appreciated by those skilled in the art that many variations, modifications, and equivalents may be made thereto without departing from the spirit and scope of the invention as defined in the claims.

Claims

1. The novel catalyst suitable for SCR denitration of the cement kiln is characterized by comprising a cuboid catalyst unit body used for bearing active ingredients of the catalyst, wherein catalyst through holes are formed in the catalyst unit, the catalyst through holes are arranged in an array mode and in the catalyst unit in a laminated mode, the cross sections of the catalyst through holes in the odd layers are regular hexagons, the cross sections of the catalyst through holes in the even layers are regular triangles, and the catalyst through holes in all layers are arranged in a staggered mode.

2. The novel catalyst suitable for SCR denitration of a cement kiln according to claim 1, wherein the size and the shape of each layer of through holes of the catalyst are consistent.

3. The novel catalyst suitable for SCR denitration of a cement kiln according to claim 1, wherein the length of the through hole of the catalyst is 200mm, the number of laminated layers is 4-6, and the height of the catalyst unit is 800-1200 mm.

4. The novel catalyst suitable for SCR denitration of a cement kiln as defined in claim 1, wherein the side length of the catalyst through hole with the cross section of a regular hexagon is 10-20 mm, and the side length of the catalyst through hole with the cross section of a regular triangle is the same as the side length of the catalyst through hole with the cross section of a regular hexagon.

5. The novel catalyst suitable for SCR denitration of a cement kiln as defined in claim 1, wherein the number of the catalyst unit cells is 13, the thickness of the inner wall is 1.5mm, the thickness of the outer wall is 2.3mm, and the aperture ratio is 0.723.

6. The novel catalyst suitable for SCR denitration of a cement kiln as defined in claim 1, wherein the boundary of each catalyst through hole with a regular hexagonal cross section is coincident with the projected position of the boundary of every six catalyst through holes with a regular triangular cross section adjacent to the catalyst through hole.

7. The novel catalyst suitable for SCR denitration of a cement kiln as defined in claim 1, wherein the catalyst is prepared by using an impregnation drying method and using an organic vanadium compound as a vanadium precursor and titanium dioxide, titanium tungsten powder or titanium molybdenum powder as a carrier.

8. The novel catalyst suitable for SCR denitration of a cement kiln according to claim 1, wherein an active component of the catalyst is vanadium pentoxide and a promoter is tungsten oxide.