SCR (Selective Catalytic Reduction) denitration catalytic device of grate-fired furnace

Abstract

The utility model provides a grate-fired furnace SCR denitration catalytic device which comprises a vertical flue, an inclined flue, a transverse flue, an ammonia spraying grid, a static mixer, a guide plate and a catalyst layer, the vertical flue, the inclined flue and the transverse flue are sequentially communicated end to end, a flue gas inlet is formed in the side wall of the vertical flue, and an outlet of the transverse flue is a flue gas outlet; the ammonia spraying grid is fixed on the inner wall of the vertical flue and is connected with an ammonia source, and an air spraying opening of the ammonia spraying grid is arranged upwards; an input port of the static mixer corresponds to the upper part of the air nozzle and is fixed on the inner wall of the vertical flue; the plurality of flow guide plates are arc-shaped plates, are arranged in parallel and are fixed at the joint of the vertical flue and the inclined flue; the SCR denitration catalytic device of the grate-fired furnace belongs to the technical field of SCR denitration, enables flue gas and ammonia gas to be fully mixed, enables a flow field to be uniform, and improves the effect of reducing nitric oxide gas.

Description

Technical Field

[0001] The utility model relates to a SCR denitration catalytic device for a layer-burning furnace, belonging to the technical field of SCR denitration. Background Art

[0002] The flue gas produced by the operation of the layer-burning furnace contains a high content of nitrogen oxide (NOx) gas. NOx is a key atmospheric pollutant in the coal combustion process, which directly or indirectly harms the environment, buildings, animals, plants, and humans. Selective catalytic reduction (SCR) technology has the advantages of high efficiency, reliability, and simple structure, and is widely used in coal-fired boilers. In the SCR denitrification system, ammonia is injected into the flue as a reducing agent, mixed with the flue gas and then flows through the catalyst layer. Under the action of the catalyst, in the temperature range of 300℃ to 400℃, ammonia and NOx, O2, etc. in the flue gas react as follows:

[0003] 4NH3+4NO+O2→4N2+6H2O NO+NO2+2NH3→2N2+3H2O

[0004] The pollutant gas NOx is reduced to harmless N2 and eventually discharged into the atmosphere.

[0005] In the prior art, the catalyst layer of the SCR denitration system is installed horizontally in the denitration longitudinal flue, and the mixed gas of flue gas and ammonia passes through the catalyst layer from top to bottom to cause a denitration reaction. The multi-layer catalyst placed horizontally in the longitudinal flue, the ash particles in the dusty flue gas are filtered down by gravity, and ash will accumulate on the surface of the catalyst layer. This will reduce the contact area between the catalyst and the flue gas and ammonia mixed gas in the denitration reaction, aggravate the wear of the ash particles and the catalyst, and even cause the catalyst to be blocked in severe cases, affecting the performance of the catalyst, making the denitration reaction incomplete, and causing high NOx emissions.

[0006] The existing patent CN201720081491.6 discloses an SCR denitration system with an inclined catalyst arrangement, in which the catalyst layer is inclined and a multi-stage impact separator is set, which can effectively solve the problem of catalyst layer dust accumulation. However, the system still has problems such as uneven flow field and easy dust accumulation in the inlet transverse flue. Utility Model Content

[0007] The technical problem to be solved by the utility model is to provide a layer-fired furnace SCR denitration catalytic device, which can fully mix the flue gas and ammonia, and can make the flow field uniform, thereby improving the effect of reducing nitrogen oxide gas.

[0008] The utility model solves the above technical problems with the following technical solutions: A layer-fired furnace SCR denitration catalytic device, comprising:

[0009] A vertical flue, an inclined flue and a transverse flue connected in sequence end to end, a smoke inlet is provided on the side wall of the vertical flue, and an outlet of the transverse flue is a smoke outlet;

[0010] An ammonia injection grid, wherein the ammonia injection grid is fixed to the inner wall of the vertical flue and a gas delivery pipe connected thereto passes through a through hole opened above the vertical flue corresponding to the flue gas inlet to connect to an ammonia source, and an air jet of the ammonia injection grid is arranged upward;

[0011] A static mixer, wherein the input port of the static mixer is arranged above the jet port and fixed on the inner wall of the vertical flue;

[0012] A plurality of guide plates for forming a uniform flow field for the mixed flue gas outputted from the static mixer and guiding the mixed flue gas to the inclined flue, wherein the plurality of guide plates are arc-shaped plates and are arranged in parallel and fixed at the connection between the vertical flue and the inclined flue;

[0013] A plurality of catalyst layers for catalyzing nitrogen oxides are arranged in parallel and at intervals and fixed on the inner wall of the inclined flue.

[0014] The beneficial effects of the utility model are as follows: the flue gas enters the vertical flue from the flue gas inlet, the ammonia spraying grid sprays ammonia toward the static mixer, the flue gas and ammonia are mixed in the static mixer, the mixed gas is guided by the guide plate to form a uniform flow field, and is reduced to nitrogen after entering the catalyst layer, thereby improving the effect of reducing nitrogen oxide gas.

[0015] On the basis of the above technical solution, the present invention can also be improved as follows.

[0016] Furthermore, the guide plate has a radius of 800 to 1000 mm and an arc of 33° to 37°.

[0017] Furthermore, the guide plate has a length of 1500-1900 mm and a width of 500-600 mm.

[0018] The beneficial effects of adopting the above further scheme are as follows: the flow guiding effect is good, and the mixed gas consisting of flue gas and ammonia can form a uniform flow field, preventing the mixed gas from having turbulent flow at the connection between the vertical flue and the inclined flue.

[0019] Furthermore, it also includes a gas rectifier, which is located between the guide plate and the catalyst layer and fixed on the inner wall of the inclined flue.

[0020] The beneficial effects of adopting the above further scheme are: preventing the mixed gas of flue gas and ammonia from being disordered, rectifying it into the catalyst layer, improving the contact effect with the catalyst layer, giving full play to all the effective area of ​​the catalyst layer, and improving the effect of reducing nitrogen oxide gas.

[0021] Furthermore, it also includes a plurality of sonic soot blowers, wherein the blowing ends of the plurality of sonic soot blowers correspond to the plurality of catalyst layers and are fixed on the inner wall of the inclined flue.

[0022] The beneficial effects of adopting the above further scheme are as follows: the sonic soot blower cleans the dust on the surface of the catalyst layer, thereby improving the circulation effect of the mixed flue gas and improving the contact effect between the mixed flue gas and the catalyst layer.

[0023] Furthermore, it also includes a screen for intercepting large particles of coal ash in the flue gas, wherein the screen is located in the vertical flue and is fixed obliquely at the flue gas inlet.

[0024] The beneficial effect of adopting the above further scheme is that large particles of coal ash carried in the flue gas are filtered at the flue gas inlet to prevent the large particles of coal ash from adhering to other components and hindering the circulation of the flue gas.

[0025] Furthermore, the inclination angle α of the barrier is 5° to 15°.

[0026] Furthermore, the material of the barrier net is stainless steel, and the mesh holes are square, and the aperture of the mesh holes is 4 to 6 mm.

[0027] Furthermore, it also includes a coal ash hopper, which is located below the smoke inlet and has an opening facing upward and is fixed to the inner wall of the vertical flue.

[0028] The beneficial effects of adopting the above further scheme are: the interception net is tilted at a certain angle to ensure the effective interception area, and large particles of coal ash fall into the coal ash hopper after being blocked by the interception net. Multiple catalyst layers are fixed in the inclined flue, which can make the ash fall into the coal ash hopper under the action of gravity.

[0029] Furthermore, the angle β between the vertical flue and the inclined flue is 45° to 55°.

[0030] The beneficial effect of adopting the above-mentioned further scheme is as follows: the angle between the movement direction of the ash particles in the flue gas and the direction of gravity is greater than 90°. The need to overcome the effect of gravity when approaching the catalyst layer can effectively reduce the ash particles reaching the catalyst layer and weaken the force of the ash particles impacting the catalyst layer, thereby greatly reducing the wear, blockage, ash ingress, ash accumulation and other problems of the catalyst layer.

[0031] The problem of low denitrification efficiency caused by uneven flow field is solved by using static mixers, guide plates, gas rectifiers and other devices, avoiding ammonia escape caused by a significant increase in ammonia water input due to low denitrification efficiency, thereby further reducing the amount of ammonia water used and saving costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1The utility model provides a structural schematic diagram of a layer combustion furnace SCR denitration catalytic device.

[0033] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0034] 1- flue gas inlet, 2- screen, 3- coal ash hopper, 4- vertical flue, 5- ammonia injection grid, 6- static mixer, 7- guide plate, 8- inclined flue, 9- gas rectifier, 10- catalyst layer, 11- sonic soot blower, 12- flue gas outlet, 13- horizontal flue. DETAILED DESCRIPTION

[0035] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0036] The utility model aims to provide a layer-fired furnace SCR denitration catalytic device to solve the problems existing in the prior art, enable flue gas and ammonia to be fully mixed, and enable a uniform flow field, thereby improving the effect of reducing nitrogen oxide gas.

[0037] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0038] The utility model provides a layer-fired furnace SCR denitration catalytic device, such as Figure 1 As shown, it includes: a vertical flue 4, an inclined flue 8 and a transverse flue 13 connected in sequence from end to end, an ammonia injection grid 5, a static mixer 6, a plurality of guide plates 7 for forming a uniform flow field for the mixed flue gas output from the static mixer 6 and guiding it to the inclined flue 8, and a plurality of catalyst layers 10 for catalyzing nitrogen oxides. A flue gas inlet 1 is provided on the side wall of the vertical flue 4, and the outlet of the transverse flue 13 is a flue gas outlet 12; the ammonia injection grid 5 is fixed to the inner wall of the vertical flue 4 and the gas pipeline connected thereto passes through the through hole opened above the vertical flue 4 corresponding to the flue gas inlet 1 to connect the ammonia source, and the jet of the ammonia injection grid 5 is arranged upward; the input port of the static mixer 6 is arranged above the corresponding jet and fixed on the inner wall of the vertical flue 4; the plurality of guide plates 7 are arc-shaped plates and are arranged in parallel and fixed at the connection between the vertical flue 4 and the inclined flue 8; the plurality of catalyst layers 10 are arranged in parallel and at intervals and fixed on the inner wall of the inclined flue 8.

[0039] The utility model provides a layer-fired furnace SCR denitration catalytic device, in which flue gas enters a vertical flue 4 from a flue gas inlet 1, an ammonia spraying grid 5 sprays ammonia toward a static mixer 6, the flue gas and ammonia are mixed in the static mixer 6, the mixed gas is guided by a guide plate 7 to form a uniform flow field, and is reduced to nitrogen after entering a catalyst layer 10, thereby improving the effect of reducing nitrogen oxide gas.

[0040] Preferably, the ammonia injection grid 5 can be a movable ammonia injection grid 5 disclosed in the existing patent CN208130799U.

[0041] Preferably, the back of the guide plate 7 has reinforcing ribs.

[0042] Preferably, the static mixer 6 can be any one of a Y-type mixer, a K-type mixer or a vortex mixer.

[0043] The mixing process of the static mixer 6 is carried out by a series of mixing units of different specifications installed in a hollow pipe. Due to the action of the mixing unit, the fluid sometimes rotates left and sometimes rotates right, constantly changing the flow mixing direction, not only pushing the central fluid to the periphery, but also pushing the peripheral fluid to the center, thereby creating a good radial mixing effect. At the same time, the rotation of the fluid itself also occurs at the interface where adjacent components are connected. This perfect radial circulation mixing effect enables the materials to be mixed evenly. The static mixer 6 is a non-moving, efficient mixing device. Through the internal parts of the mixing unit fixed in the tube, two or more fluids are cut, sheared, rotated and remixed, so as to achieve the purpose of good dispersion and sufficient mixing between the fluids.

[0044] In a specific embodiment of the present invention, further, the radius of the guide plate 7 is 800-1000 mm, and the curvature is 33°-37°.

[0045] In a specific embodiment of the present invention, the guide plate 7 has a length of 1500-1900 mm and a width of 500-600 mm.

[0046] The flow guiding effect is good, and the mixed gas composed of the flue gas and ammonia can form a uniform flow field, thereby preventing the mixed gas from having turbulent flow at the connection between the vertical flue 4 and the inclined flue 8.

[0047] In a specific embodiment of the utility model, a gas rectifier 9 is further included. The gas rectifier 9 is located between the guide plate 7 and the catalyst layer 10 and is fixed on the inner wall of the inclined flue 8 .

[0048] The mixed gas of flue gas and ammonia is prevented from being disordered, and enters the catalyst layer 10 after rectification, thereby improving the contact effect with the catalyst layer 10, giving full play to all the effective areas of the catalyst layer 10, and improving the effect of reducing nitrogen oxide gas.

[0049] The gas rectifier 9 is a device for changing an irregularly flowing airflow into a regularly flowing airflow, or changing a rotating airflow into a linearly flowing airflow.

[0050] In a specific embodiment of the utility model, a plurality of sonic soot blowers 11 are further included. The blowing ends of the plurality of sonic soot blowers 11 correspond to the plurality of catalyst layers 10 and are fixed on the inner wall of the inclined flue 8 .

[0051] The sonic soot blower 11 cleans the dust on the surface of the catalyst layer 10 , thereby improving the circulation effect of the mixed flue gas and the contact effect between the mixed flue gas and the catalyst layer 10 .

[0052] Preferably, the catalyst layer 10 is perpendicular to the axis of the inclined flue 8, and the sonic soot blower 11 is blown regularly or irregularly to clean the catalyst layer 10 to prevent blockage and dust accumulation.

[0053] Preferably, a plurality of sonic soot blowers 11 are disposed one by one below a plurality of catalyst layers 10 along the direction of the inclined flue 8 , so as to facilitate cleaning of dust attached to the catalyst layers 10 .

[0054] Preferably, the guide plate 7 is made of Q235 carbon steel.

[0055] In a specific embodiment of the utility model, a blocking net 2 for intercepting large particles of coal ash in the flue gas is also included. The blocking net 2 is located in the vertical flue 4 and is fixed at an angle at the flue gas inlet 1.

[0056] At the flue gas inlet 1, large particles of fly ash carried in the flue gas are filtered to prevent the large particles of fly ash from adhering to other components and hindering the flow of flue gas.

[0057] In a specific embodiment of the utility model, the inclination angle α of the barrier net 2 is 5° to 15°.

[0058] In a specific embodiment of the utility model, the material of the barrier net 2 is stainless steel, and the mesh holes are square, and the aperture of the mesh holes is 4-6 mm.

[0059] Preferably, the material of the barrier net 2 is 316L or 2250 stainless steel.

[0060] In a specific embodiment of the utility model, a coal ash hopper 3 is further included. The coal ash hopper 3 is located below the smoke inlet 1 and its opening faces upward and is fixed to the inner wall of the vertical flue 4 .

[0061] The intercepting net 2 is tilted at a certain angle to ensure the effective interception area, and allows large particles of coal ash to fall into the coal ash hopper 3 after being blocked by the intercepting net. Multiple catalyst layers 10 are fixed in the inclined flue 8, which can allow the ash to fall into the coal ash hopper 3 under the action of gravity.

[0062] Preferably, when the furnace is shut down, the coal ash hopper 3 can be opened to clean the ash accumulated in the flue.

[0063] In a specific embodiment of the present invention, the angle β between the vertical flue 4 and the inclined flue 8 is 45° to 55°.

[0064] By making the angle between the movement direction of the ash particles in the flue gas and the direction of gravity greater than 90°, the ash particles approaching the catalyst layer 10 need to overcome the effect of gravity, which can effectively reduce the ash particles reaching the catalyst layer 10 and weaken the force of the ash particles impacting the catalyst layer 10, thereby greatly reducing the problems of wear, blockage, ash ingress, ash accumulation, etc. of the catalyst layer 10.

[0065] The problem of low denitration efficiency caused by uneven flow field is solved by means of static mixer 6, guide plate 7, gas rectifier 9 and other devices, avoiding ammonia escape caused by a significant increase in ammonia water input due to low denitration efficiency, thereby further reducing the amount of ammonia water used and saving costs.

[0066] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A layer-fired furnace SCR denitration catalytic device, characterized in that: include: A vertical flue (4), an inclined flue (8) and a transverse flue (13) connected in sequence end to end, a smoke inlet (1) being provided on the side wall of the vertical flue (4), and an outlet of the transverse flue (13) being a smoke outlet (12); an ammonia injection grid (5), wherein the ammonia injection grid (5) is fixed to the inner wall of the vertical flue (4) and a gas transmission pipe connected thereto passes through a through hole opened above the vertical flue (4) corresponding to the flue gas inlet (1) to connect to an ammonia source, and the gas injection port of the ammonia injection grid (5) is arranged upward; a static mixer (6), wherein an input port of the static mixer (6) is arranged above the jet port and fixed on the inner wall of the vertical flue (4); a plurality of guide plates (7) for forming a uniform flow field for the mixed flue gas outputted from the static mixer (6) and guiding the mixed flue gas to the inclined flue (8); the plurality of guide plates (7) are arc-shaped plates and are arranged in parallel and fixed at the connection between the vertical flue (4) and the inclined flue (8); A plurality of catalyst layers (10) for catalyzing nitrogen oxides, wherein the plurality of catalyst layers (10) are arranged in parallel and at intervals and fixed on the inner wall of the inclined flue (8).

2. A grate furnace SCR denitration catalytic device according to claim 1, characterized in that: The guide plate (7) has a radius of 800 to 1000 mm and an arc of 33° to 37°.

3. A grate furnace SCR denitration catalytic device according to claim 2, characterized in that: The guide plate (7) has a length of 1500-1900 mm and a width of 500-600 mm.

4. The SCR denitration catalytic device for a grate-fired furnace according to claim 1, characterized in that: It also comprises a gas rectifier (9), which is located between the guide plate (7) and the catalyst layer (10) and fixed on the inner wall of the inclined flue (8).

5. The SCR denitration catalytic device for a grate-fired furnace according to claim 1, characterized in that: It also comprises a plurality of sonic soot blowers (11), the blowing ends of the plurality of sonic soot blowers (11) corresponding to the plurality of catalyst layers (10) and fixed on the inner wall of the inclined flue (8).

6. The SCR denitration catalytic device for a grate-fired furnace according to claim 1, characterized in that: It also comprises a screen (2) for intercepting large particles of coal ash in the flue gas, wherein the screen (2) is located in the vertical flue (4) and is fixed obliquely at the flue gas inlet (1).

7. A grate furnace SCR denitration catalytic device according to claim 6, characterized in that: The inclination angle α of the barrier net (2) is 5° to 15°.

8. The SCR denitration catalytic device for a grate-fired furnace according to claim 6, characterized in that: The material of the blocking net (2) is stainless steel, and the mesh holes are square, and the aperture of the mesh holes is 4 to 6 mm.

9. The SCR denitration catalytic device for a grate-fired furnace according to claim 1, characterized in that: It also comprises a coal ash hopper (3), which is located below the smoke inlet (1) and has an opening facing upward and is fixed to the inner wall of the vertical flue (4).

10. The SCR denitration catalytic device for a grate-fired furnace according to claim 1, characterized in that: The included angle β between the vertical flue (4) and the inclined flue (8) is 45° to 55°.

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