CN210674809U - Ammonia injection mixed flow device of SCR denitration system - Google Patents
Ammonia injection mixed flow device of SCR denitration system Download PDFInfo
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- CN210674809U CN210674809U CN201921090945.1U CN201921090945U CN210674809U CN 210674809 U CN210674809 U CN 210674809U CN 201921090945 U CN201921090945 U CN 201921090945U CN 210674809 U CN210674809 U CN 210674809U
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Abstract
The utility model relates to a SCR deNOx systems's ammonia sprays mixed flow device, including ammonia injection unit and static mixer (3), ammonia injection unit includes interconnect's ammonia pipe (1) and nozzle (2) of spouting, static mixer (3) include guide plate subassembly, nozzle (2) are curve tooth conical gear shape, and gradually expand along ammonia injection direction, guide plate subassembly includes a plurality of trapezoidal plates (4) to and connect planar plate (5) that a plurality of trapezoidal plates (4) are close to nozzle (2) one end respectively, planar plate (5) are parallel with nozzle (2) cross section, a plurality of trapezoidal plates (4) are radially along ammonia injection direction. Compared with the prior art, can make the ammonia just form rotatory disturbance in nozzle (2), increase the mixed perimeter of ammonia and flue gas, solve the initial relatively poor problem of flue gas mixing efficiency of spouting into with of ammonia effectively.
Description
Technical Field
The utility model belongs to the technical field of flue gas environmental protection denitration and specifically relates to an ammonia injection mixed flow device of SCR deNOx systems is related to.
Background
The Selective Catalytic Reduction (SCR) method is the most widely applied flue gas denitration technology of power plants at home and abroad at present, a reducing agent (NH3) is sprayed into a flue through a pipeline and is subjected to catalytic reduction reaction with nitrogen oxide (NOx) in the flue under the action of a catalyst to generate N2 and H2O, so that the emission of the NOx is effectively reduced, and the aim of denitration is fulfilled. In order to ensure denitration efficiency, it is necessary to ensure that NH3 and NOx are uniformly mixed before reaching the catalyst inlet. However, in an actual power plant, due to the limitations of the length of the front flue of the catalyst inlet, abrupt change of the section, uneven flow field and the like, the NH3 and the NOx are difficult to be uniformly mixed.
In prior art, flue gas and ammonia are all mixed the device and are put the common two kinds of modes that have, and the first one is the ammonia injection grid that adopts circular nozzle formula, and the cooperation guide plate carries out the vortex, and general guide plate number and nozzle number one-to-one correspond. The method has the characteristics of simple process, low mixing efficiency of the flue gas and the ammonia, and long mixing channels for uniform mixing. The second mode is to adjust the flow of the ammonia spraying pipe and the opening of a nozzle valve by partition so as to match the incoming flow of flue gas, but the mode is complex in actual operation. Therefore, the design of the ammonia injection device needs to consider avoiding complex operation and simultaneously improving the mixing uniformity of the flue gas and the ammonia in the limited flue.
SUMMERY OF THE UTILITY MODEL
The utility model aims at providing an SCR deNOx systems's ammonia sprays mixed flow device in order to overcome the defect that above-mentioned prior art exists.
The purpose of the utility model can be realized through the following technical scheme:
the utility model provides a SCR deNOx systems's ammonia sprays mixed flow device, includes ammonia injection unit and static mixer, ammonia injection unit includes interconnect's the ammonia pipe and the nozzle of spouting, static mixer includes guide plate assembly, the nozzle is curve tooth conical gear shape, and sprays the direction and gradually expands along the ammonia, guide plate assembly includes a plurality of trapezoidal boards to and connect the plane board that a plurality of trapezoidal boards are close to nozzle one end respectively, the plane board is parallel with the nozzle cross section, a plurality of trapezoidal boards are radially along ammonia injection direction, and the ammonia is spout after rotatory in the nozzle, mixes through guide plate assembly and flue gas.
The curve teeth are S-shaped curve teeth.
The plane plate is in a regular polygon shape or a circular shape.
The included angle between the trapezoidal plates and the central axis of the plane plate is 15-60 degrees.
The plurality of trapezoidal plates are uniformly distributed around the plane plate.
The plurality of trapezoidal plates are arranged at intervals.
The number of the curve teeth is equal to the number of the trapezoidal plates.
The expansion angle of the nozzle stream is 15-60 degrees.
The number of the curve teeth is 4-12.
The plurality of trapezoidal plates increase in width in the ammonia gas injection direction.
Compared with the prior art, the utility model has the advantages of it is following:
(1) the conical gear-shaped nozzle with the curved teeth can enable ammonia gas to form rotary disturbance in the nozzle, increase the mixing perimeter of the ammonia gas and flue gas, and effectively solve the problem that the mixing efficiency of the ammonia gas and the flue gas is poor when the ammonia is initially sprayed into a flue.
(2) The static mixer comprises a plurality of trapezoidal plates and a plane plate which is respectively connected with one end of each trapezoidal plate close to the nozzle and matched with the curve-tooth conical gear-shaped nozzle, so that the disturbance range of ammonia can be further enlarged, the ammonia is better diffused and mixed with flue gas, and the uniform mixing of the flue gas and the ammonia is realized in a shorter space distance.
(3) The operation is convenient, the structure is simple, the cost is lower, and the realization is easier.
(4) The curved teeth are S-shaped curved teeth, so that the rotary disturbance on the ammonia gas can be better formed.
(5) The plane board is regular polygon or circular, and a plurality of trapezoidal boards encircle plane board evenly distributed, and a plurality of trapezoidal boards interval sets up, and curve tooth quantity equals a plurality of trapezoidal boards quantity, and curve tooth quantity is 4 ~ 12, increases along a plurality of trapezoidal board widths of ammonia injection direction, makes static mixer can exert better mixed action.
(6) The flow expansion angle of the nozzle is 15-60 degrees, the included angle between the trapezoidal plate and the central axis of the plane plate is 15-60 degrees, so that the static mixer can be better matched with the nozzle to achieve better mixing effect.
Drawings
Fig. 1 is a schematic structural view of the present invention;
FIG. 2 is a perspective view of the nozzle of the present invention;
FIG. 3 is a front perspective view of the nozzle of the present invention along the ammonia gas injection direction;
FIG. 4 is a rear perspective view of the nozzle of the present invention along the flow direction of flue gas;
FIG. 5 is a schematic structural diagram of the static mixer of the present invention;
fig. 6 is a front view of the baffle assembly of the present invention;
fig. 7(a) is a flow chart of the air velocity at the outlet face of the nozzle of the present invention in example 1;
FIG. 7(b) is a flow chart of the air flow velocity at the outlet face of the conventional circular nozzle in example 1;
fig. 8(a) is a partial enlarged view of a flow chart of the air velocity at the outlet face of the nozzle of the present invention in example 1;
FIG. 8(b) is a partially enlarged view of a flow chart of the air flow velocity at the outlet face of the conventional circular nozzle in example 1;
FIG. 9(a) is a schematic view showing a rear NH part of a deflector according to the present invention in example 13A concentration cloud graph;
FIG. 9(b) is a diagram showing the NH behind the conventional baffle in example 13A concentration cloud graph; reference numerals:
1 is an ammonia spraying pipe; 2 is a nozzle; 3 is a static mixer; 4 is a plurality of trapezoidal plates; 5 is a plane plate.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. The embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation manner and a specific operation process are given, but the scope of the present invention is not limited to the following embodiments.
Examples
Example 1
Fig. 1 shows that an ammonia sprays mixed flow device suitable for SCR deNOx systems, including ammonia injection unit and static mixer 3, the ammonia injection unit is including spouting ammonia pipe 1 and nozzle 2, uses one to spout the ammonia pipe as the embodiment, and the equipartition is gone up to the pipe two curve tooth conical gear shape's nozzle 2, and every nozzle 2 rear corresponds a static mixer 3.
As shown in fig. 2, 3 and 4, the curved teeth are S-shaped curved teeth, i.e. the ammonia gas flow can be rotated in the channel of the nozzle 2; the export cross-section is the gear type, contains 6 groups of addendums and 6 groups of tooth roots, and whole addendum (tooth root) is located and uses the tip circle (root circle) of cross-section center as the centre of a circle, and in fig. 4, the line of adjacent addendum point a and tooth root point b is through the centre of a circle, and the angle that each addendum or tooth root was around the centre of a circle is 30, and full tooth height is 0.03m, and the addendum circle radius is 0.11m, and the root circle radius is 0.08 m. The center of the ammonia gas inlet face of the nozzle 2 was spaced apart from the tooth root by a vertical distance of 0.05 m.
As shown in fig. 5, 6, static mixer 3 is located the nozzle 2 dead astern, every static mixer 3 contains 6 vertical trapezoidal boards and a positive 12 limit shape plane board, 6 vertical trapezoidal boards are radial along ammonia injection direction, positive 12 limit shape plane board is located the nozzle 2 export dead astern, parallel with 2 cross sections of nozzle, and 6 vertical trapezoidal boards of seamless connection are close to 2 one ends of nozzle, the perpendicular distance apart from 2 ammonia outlet faces of nozzle is 0.2m, the girth of positive 12 limit shape plane board is less than the girth of the root of tooth circle on the 2 ammonia outlet faces of nozzle.
In this example, the flow field and flow characteristics of the conventional circular straight nozzle (referred to as type i) and the curved-tooth conical-gear-shaped nozzle 2 (referred to as type ii) of this example were compared. The comparison principle is as follows, the flue gas inlet flow rate and the ammonia gas inlet flow rate are matched. According to the SCR chemical reaction formula, NO and NH3The ratio of the amounts of substances (A) to (B) is 1, and NO and NH are converted from the volume flow rate3The ratio of the inlet velocities. And a variable control method is adopted, wherein the calculation domains of the two simulations are the same, the size arrangement of the ammonia spraying pipes 1 is the same, and the inlet speeds are correspondingly equal. The ammonia gas inlet of the nozzle 2 of the present embodiment and the ammonia gas inlet of the conventional circular nozzle have the same area, and are 1.83X 10-4m2Wherein the perimeter of the ammonia gas inlet of the I-shaped nozzle is 0.504m, and the hydraulic diameter is 1.45 multiplied by 10-3The perimeter of the inlet of the m, II type nozzle 2 is 0.913m, and the hydraulic diameter is 8.02 multiplied by 10-4m。
Fig. 7(a) and 8(a) show the flow charts of ammonia gas at the outlet section of the nozzle 2 in the embodiment, because the channel of the nozzle 2 is a rotating divergent gear, and the curved teeth are S-shaped curved teeth, the ammonia gas rotates at high speed in the channel of the nozzle 2, and a vortex region is formed behind each tooth peak, and the vortex region guides the convective mixing of ammonia gas flow and flue gas flow; two eddy regions with opposite directions are formed in the central area of the outlet section to enable the central ammonia gas flow to be diffused in the radial direction; the contact perimeter of ammonia gas spraying and horizontal flue gas is increased, and the mixing between the ammonia gas spraying and the horizontal flue gas is enhanced; the mixing efficiency of the ammonia gas and the flue gas during initial injection is low, and the improvement effect is obvious. In contrast, the ammonia gas had no turbulence in the rear center region of the conventional circular nozzle, and the calculation results are shown in fig. 7(b) and fig. 8 (b). As can be seen from the figure, the disturbance range of the air flow outside the central area is smaller than that of the embodiment, about 32.5% of the embodiment, and the good effect of mixing with the flue gas in the initial stage is not achieved. The nozzle 2 in the shape of the curved-tooth conical gear has the advantages that the circumference of the nozzle 2 in the shape of the curved-tooth conical gear is longer than that of a traditional circular nozzle and a conical flared nozzle, and the contact area of ammonia gas flow and incoming flow smoke is increased. For example, in this embodiment, the nozzle 2 perimeter is 1.995 times larger than a conventional circular nozzle.
FIG. 9 shows NH when a single nozzle 2 is spraying ammonia3When the diffusion concentration after the static mixer 3 is taken on the same plane, the NH concentration in FIG. 9(a) can be found by comparing the two graphs of FIG. 9(a) and FIG. 9(b)3After this embodiment static mixing device, behind the blender, diffusion in the place ahead of the catalyst layer is more abundant, compares figure 9(b) traditional circular static mixer, has increased the mixed perimeter of ammonia and flue gas, makes the more even mixture of the two.
Example 2
Every static mixer 3 contains 6 arc trapezoidal plates and a circular plane board, and 6 arc trapezoidal plates are close to 2 one ends of nozzle and form circularly, and 6 arc trapezoidal plates of circular plane board seamless connection are close to 2 one ends of nozzle. The rest is the same as example 1.
Example 3
The quantity of curve tooth and straight trapezoidal plate is 10, and positive 20 edges shape connects 10 straight trapezoidal plates and is close to nozzle 2 one end. The rest is the same as example 1.
Example 4
The included angle between the straight trapezoidal plate and the central axis of the regular 12-sided polygon plane plate is 50 degrees, and the rest is the same as the embodiment 1.
The principle and the implementation of the present invention are explained herein by using specific examples, and the above description of the embodiments is only used to help understand the method and the core idea of the present invention; meanwhile, for the general technical personnel in the field, according to the idea of the present invention, there are changes in the concrete implementation and the application scope. In summary, the content of the present specification should not be construed as a limitation of the present invention.
Claims (10)
1. The utility model provides a SCR deNOx systems's ammonia sprays mixed flow device, includes ammonia injection unit and static mixer (3), ammonia injection unit includes interconnect's ammonia pipe (1) and nozzle (2) of spouting, static mixer (3) include guide plate subassembly, its characterized in that, nozzle (2) are curved tooth conical gear shape, and gradually expand along ammonia injection direction, guide plate subassembly includes a plurality of trapezoidal plates (4) to and connect respectively a plurality of trapezoidal plates (4) and be close to plane board (5) of nozzle (2) one end, plane board (5) are parallel with nozzle (2) cross section, a plurality of trapezoidal plates (4) are radially along ammonia injection direction.
2. The ammonia injection flow mixing device of the SCR denitration system of claim 1, wherein the curved teeth are S-shaped curved teeth.
3. The ammonia injection flow mixing device of the SCR denitration system as set forth in claim 1, wherein said flat plate (5) is in the shape of a regular polygon or a circle.
4. The ammonia injection flow mixing device of the SCR denitration system according to claim 3, wherein the included angle between the plurality of trapezoidal plates (4) and the central axis of the plane plate (5) is 15-60 °.
5. The ammonia injection flow mixing device of the SCR denitration system as set forth in claim 1, wherein said plurality of trapezoidal plates (4) are uniformly distributed around said flat plate (5).
6. The ammonia injection flow mixing device of the SCR denitration system as set forth in claim 1, wherein said plurality of trapezoidal plates (4) are arranged at intervals.
7. The ammonia injection flow mixing device of the SCR denitration system as set forth in claim 1, wherein the number of said curved teeth is equal to the number of said plurality of trapezoidal plates (4).
8. The ammonia injection flow mixing device of the SCR denitration system according to claim 1, wherein the stream spreading angle of the nozzle (2) is 15-60 °.
9. The ammonia injection flow mixing device of the SCR denitration system of claim 1, wherein the number of the curve teeth is 4-12.
10. The ammonia injection flow mixing device of an SCR denitration system according to claim 1, wherein the plurality of trapezoidal plates (4) increase in width in the ammonia gas injection direction.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110193285A (en) * | 2019-07-12 | 2019-09-03 | 中电华创(苏州)电力技术研究有限公司 | A kind of ammonia injection flow mixing device of SCR denitration system |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110193285A (en) * | 2019-07-12 | 2019-09-03 | 中电华创(苏州)电力技术研究有限公司 | A kind of ammonia injection flow mixing device of SCR denitration system |
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