JP4335504B2 - Fluid mixing apparatus and control method thereof - Google Patents

Description

表１から、本発明の流体混合装置を使用することにより、ＮＨ₃ 注入ノズルの設置が１本であっても均質混合ガスを安定して得られることが示される。
【００１６】
【発明の効果】
請求項１および２記載の発明によれば、異種流体を注入するノズルを流体混合装置内に設け、該異種流体を該装置の空間内で激しく乱れた領域を形成する主流体に混入して混合させるため、該流体混合装置前流の主流体の不均質度に影響されることなく、かつ少ない数のノズルの設置で、必要な均質度を有する混合ガスを容易にかつ安定して得ることができる。
また請求項３および４記載の発明によれば、上記ノズルに流量等の調整手段を設けて該ノズルから混入する流体の流量等を調整することにより、さらに均質な混合ガスを容易に得ることができる。
さらに請求項５記載の発明によれば、上記で得た均質な混合ガスを脱硝装置に供給することにより、該脱硝装置の脱硝率を大幅に向上させることができる。
【図面の簡単な説明】
【図１】本発明の一実施例を示す流体混合装置の説明図。
【図２】図１の流体混合部の断面説明図。
【図３】本発明の他の実施例を示す流体混合装置の説明図。
【図４】従来技術による流体混合装置の説明図。
【図５】図４の流体混合部の断面説明図。
【符号の説明】
１Ａ…排ガス、１Ｂ…不均質ガス、２…流路分割部材、３ａ、３ｂ、３ｃ、３ｄ…ガス噴出部、４…排ガスダクト、５…ＮＨ₃ 注入ノズル、６…均質混合ガス、７…四角錐状混合装置、９…ＮＨ₃ ガス、Ｘ…第一の空間、Ｙ…第二の空間。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fluid mixing apparatus, and more specifically, a fluid mixing apparatus capable of greatly promoting mixing of different kinds of fluids with a small number of nozzles and easily obtaining a required degree of mixing, and a control method thereof, and The present invention relates to an exhaust gas denitration device using a fluid mixing device.
[0002]
[Prior art]
Exhaust gas discharged from combustion devices such as boilers and heating furnaces contains harmful nitrogen oxides (NOx). As a general apparatus for removing NOx in exhaust gas, an exhaust gas denitration apparatus by a selective catalytic reduction method is known, and ammonia (NH ₃ ) is generally used as a reducing agent. In addition, the conventional exhaust gas denitration apparatus has an exhaust gas duct having an inlet of exhaust gas discharged from a combustion apparatus, etc., and a denitration apparatus equipped with a denitration catalyst that reduces NOx in the exhaust gas by a selective catalytic reduction method. the exhaust gas duct upstream side of the apparatus, the fluid mixing device is provided with a fluid mixing portion for mixing the NH ₃ injection nozzles and the exhaust gas and NH ₃ gas injecting NH _3. A high denitration rate can be obtained by installing a fluid mixing device in the exhaust gas duct, mixing the exhaust gas and NH ₃ homogeneously, and introducing the mixed gas into the denitration device.
[0003]
FIG. 4 is an explanatory view of a fluid mixing device according to the prior art, and FIG. 5 is a cross-sectional explanatory view of a fluid mixing portion of this device. Such an apparatus is proposed in, for example, Japanese Patent Laid-Open No. 7-227528.
In FIG. 4, the fluid mixing device includes an exhaust gas duct 4 into which exhaust gas 1A discharged from a combustion device (not shown) is introduced, a plurality of NH ₃ injection nozzles 5 provided in the exhaust gas duct 4, and the NH ₃ injection nozzles. And a quadrangular pyramid mixing device 7 for homogeneously mixing the NH ₃ gas injected from 5 and the heterogeneous gas 1B including the exhaust gas 1A. In addition, the quadrangular pyramid mixing device 7 includes a quadrangular pyramid-shaped channel dividing member 2 provided in the exhaust gas duct 4 and a pair of gas ejection portions 3 a provided on opposing wall surfaces of the channel dividing member 2. , 3b and 3c and 3d, the flow path dividing member 2 includes a first space X surrounded by an outer wall of the exhaust gas dust 4 in its front stream as shown in FIG. A second space Y surrounded by the internal partition walls of the flow path dividing member 2 is formed.
[0004]
In such a configuration, the exhaust gas 1A introduced into the exhaust gas duct 4 is mixed with the NH ₃ gas injected from the plurality of NH ₃ injection nozzles 5 in the first space X to become the heterogeneous gas 1B. The heterogeneous gas 1B is blocked by the flow path dividing member 2, and flows into the second space Y from the gas ejection portions 3a, 3b, 3c, and 3c provided in the flow path dividing member 2. As shown in FIG. 5, the inhomogeneous gas 1B that has passed through the gas ejection portions 3a, 3b, 3c, and 3c collides violently with each other in the second space Y, thereby being agitated with each other and the homogeneous mixed gas 6 and Become.
However, the fluid mixing device has a problem that the homogeneity of the mixed gas at the outlet of the quadrangular pyramid mixing device 7 depends on the homogeneity of the exhaust gas and the NH ₃ gas in the first space X in the upstream flow. . In order to solve such a problem, a method has been proposed in which the number of NH ₃ injection nozzles installed in the exhaust gas duct is increased to improve the homogeneity of the exhaust gas and NH ₃ gas in the first space X. However, it is difficult to adjust the flow rate of NH ₃ injected from each nozzle according to the properties such as the cross-sectional flow velocity distribution and NOx concentration distribution of the exhaust gas in the duct, and it is necessary to install many nozzles. In addition, there is a problem that installing a flow rate adjusting valve for each nozzle to adjust the amount of NH ₃ injected from each nozzle further increases the equipment cost.
[0005]
As another prior art, there has been proposed a denitration device in which a plurality of disc-shaped mixing devices are installed in a duct and ammonia is injected into the downstream side thereof. This denitration system has a structure that promotes mixing of ammonia and exhaust gas by Karman vortex generated in the wake of the disk, but the exhaust gas near the duct wall and between the disks is outside the area affected by the Karman vortex. There is a problem that a portion not affected by the mixing action due to the gas occurs, and the homogeneity of the mixed gas cannot be improved.
As described above, in the former case, there is a problem that the homogeneity of the fluid at the inlet of the mixing device affects the homogeneity of the outlet of the mixing device. In the latter case, there is a gas flow in which part of the fluid in the duct is not included in the affected area of the disc-shaped mixing device, and no consideration has been given to the gas flow. There was a limit to the improvement of homogeneity.
[0006]
[Problems to be solved by the invention]
An object of the present invention is to solve the above-mentioned problems of the prior art, to greatly promote the mixing of different fluids with a small number of nozzles, and to easily obtain the required degree of mixing, and to the same It is an object to provide a control method and an exhaust gas denitration apparatus using the fluid mixing apparatus.
[0007]
[Means for Solving the Problems]
As a result of intensive studies in view of the above problems, the present inventors have provided a member that once divides the flow path of the main fluid in the duct, and provided a pair of fluid outlets opposed to the member. By injecting a fluid different from the main fluid into the highly disturbed main fluid ejected from the outlet, it was found that the heterogeneous fluid injected by the stirring action of the main fluid can be mixed efficiently and homogeneously, and the present invention has been achieved. Is.
The invention claimed in the present application in order to achieve the above object is as follows.
[0008]
(1) A second space surrounded by an internal partition wall having a fluid outlet is formed in a duct forming a first space surrounded by an outer wall having a fluid inlet. A fluid mixing device in which a pair of fluid jets leading from the first space to the second space are opposed to each other in the inner partition that separates the space of the second partition , A fluid mixing apparatus , wherein a nozzle for mixing a fluid having a composition different from that of the fluid is provided in an area where fluid ejected from the fluid ejection ports arranged opposite to each other directly collides and interferes .
(2) The fluid mixing apparatus according to (1), wherein a plurality of sets of the second space and the nozzle are provided in a cross section orthogonal to the fluid flow direction in the duct.
(3) When mixing different fluids using the fluid mixing device according to (1) or (2), adjusting the flow rate or concentration of the fluid mixed from the nozzle so that the fluid after mixing is homogeneous. A control method for a fluid mixing apparatus.
(4) The fluid mixed from the nozzle is an ammonia-containing gas, and the flow rate or ammonia concentration of the ammonia-containing gas mixed from the nozzle is adjusted so that the mixed fluid becomes homogeneous (3) A control method of the fluid mixing apparatus described.
(5) An exhaust gas denitration apparatus comprising a duct having an inlet for exhaust gas containing a nitrogen compound and a denitration apparatus provided at the outlet of the duct, wherein the fluid mixing apparatus according to (1) or (2) is provided in the duct An exhaust gas denitration apparatus characterized by comprising:
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings.
FIG. 1 is an explanatory view of a fluid mixing apparatus showing an embodiment of the present invention, and FIG. 2 is a cross-sectional explanatory view of a fluid mixing section of this apparatus.
1 and 2 are different from FIGS. 4 and 5 in that a large number of NH ₃ injection nozzles 5 are provided in the upstream (first space X) of the quadrangular pyramid mixing device 7 provided in the exhaust gas duct 4. Instead, one NH ₃ injection nozzle 5 is provided inside the quadrangular pyramid mixing device 7 (second space Y), and the exhaust gas 1A and the NH ₃ gas 9 are mixed in the second space Y. This is the point.
[0010]
In such an apparatus, the exhaust gas 1A in the exhaust gas duct 4 flows into the second space Y from the gas ejection portions 3a and 3b and 3c and 3d provided facing the flow path dividing member 2 of the quadrangular pyramid mixing device 7. Here, the exhaust gases 1A directly collide with each other or interfere with each other, and an extremely turbulent region of the exhaust gases 1A is formed in the space Y. On the other hand, the NH ₃ gas is supplied into the region from the NH ₃ injection nozzle 5 provided in this region, is vigorously mixed with the turbulent exhaust gas 1A, is homogenized, and becomes a homogeneous mixed gas 6.
[0011]
In this way, the NH ₃ gas 9 is vigorously mixed with the highly disturbed exhaust gas 1A in the second space Y formed by the quadrangular pyramid mixing device 7, so that the homogeneity of the obtained homogeneous mixed gas 6 is four. The homogeneous mixed gas 6 having the required homogeneity can be easily obtained without depending on the inhomogeneity of the exhaust gas upstream of the pyramid mixing device 7. Further, by installing a flow rate or concentration control valve on the NH ₃ injection nozzle 5 and adjusting the flow rate or concentration of the NH ₃ gas 9 in accordance with the inhomogeneity of the exhaust gas 1A and the homogeneity of the obtained homogeneous mixed gas, further homogeneity is achieved. A simple mixed gas can be obtained easily.
The obtained homogeneous mixed gas 6 is supplied to a denitration apparatus installed in the downstream (not shown), contacts with a catalyst provided in the denitration apparatus, and nitrogen oxides in the exhaust gas are reduced and removed. By supplying a highly homogeneous mixed gas to the denitration apparatus, the denitration rate can be improved.
[0012]
In the present invention, the flow path dividing member constituting the fluid mixing device is a quadrangular pyramid as long as a pair of gas ejection portions can be provided to face each other and the second space Y can be formed in the exhaust gas duct. For example, it may be a mountain shape.
A plurality of sets of fluid mixing devices and NH ₃ injection nozzles installed in the fluid mixing device may be installed in the gas flow direction in the exhaust gas duct or in a cross section orthogonal to the gas flow direction. In the above description, the different fluids of the exhaust gas and NH ₃ are mixed. However, the present invention is not limited to these, and other different fluids may be used.
[0013]
FIG. 3 is an explanatory view of a fluid mixing apparatus showing another embodiment of the present invention.
3 differs from FIG. 1 in that four combinations of the quadrangular pyramid mixing device 7 and the NH ₃ injection nozzle 5 are provided in a cross section orthogonal to the exhaust gas flow direction in the exhaust gas duct 4. The exhaust gas 1A and the NH ₃ gas 9 are mixed in the respective interiors (second space Y). Thus, even if the mixed gas required in the downstream of the mixing apparatus cannot be obtained by installing a plurality of sets of the quadrangular pyramid mixing apparatuses 7 and the NH ₃ injection nozzles 5, the homogeneity is obtained. By adjusting the amount of NH ₃ gas injected from the nozzle in a low region, it is possible to easily obtain a mixed gas having the required homogeneity.
[0014]
【Example】
Hereinafter, the present invention will be described in detail with reference to examples.
Example 1 and Comparative Examples 1 and 2
The exhaust gas and NH ₃ gas were mixed using the respective fluid mixing devices shown in FIGS. 1 and 4. The mixing conditions at this time were exhaust gas flow velocity: 15 m / s, exhaust gas temperature: normal temperature, and NH ₃ gas flow velocity: 15 m / s.
The homogeneity of the exhaust gas at the inlet of the fluid mixing device and the homogeneity of the mixed gas at the outlet of the mixing device were measured, and the coefficient of variation was determined by the following equation. The results are shown in Table 1.
Coefficient of variation (%) = [standard deviation value / average value of homogeneity] × 100
[0015]
[Table 1]

Table 1 shows that by using the fluid mixing apparatus of the present invention, a homogeneous mixed gas can be stably obtained even if only one NH ₃ injection nozzle is installed.
[0016]
【The invention's effect】
According to the first and second aspects of the present invention, the nozzle for injecting the different fluid is provided in the fluid mixing device, and the different fluid is mixed and mixed with the main fluid forming a turbulent region in the space of the device. Therefore, it is possible to easily and stably obtain a mixed gas having the required degree of homogeneity without being affected by the inhomogeneity of the main fluid upstream of the fluid mixing apparatus and by installing a small number of nozzles. it can.
According to the third and fourth aspects of the invention, it is possible to easily obtain a more homogeneous mixed gas by providing the nozzle with adjusting means such as a flow rate and adjusting the flow rate of the fluid mixed from the nozzle. it can.
Furthermore, according to the fifth aspect of the present invention, by supplying the homogeneous mixed gas obtained above to the denitration device, the denitration rate of the denitration device can be greatly improved.
[Brief description of the drawings]
FIG. 1 is an explanatory view of a fluid mixing apparatus showing an embodiment of the present invention.
2 is a cross-sectional explanatory view of the fluid mixing unit in FIG. 1;
FIG. 3 is an explanatory view of a fluid mixing apparatus showing another embodiment of the present invention.
FIG. 4 is an explanatory view of a fluid mixing apparatus according to the prior art.
FIG. 5 is a cross-sectional explanatory view of the fluid mixing unit in FIG. 4;
[Explanation of symbols]
1A ... exhaust gas, 1B ... heterogeneous gas, 2 ... flow path dividing member, 3a, 3b, 3c, 3d ... gas ejection unit, 4 ... exhaust gas duct, 5 ... NH ₃ injection nozzle, 6 ... intimately mixed gas, 7 ... four Pyramidal mixing device, 9 ... NH ₃ gas, X ... first space, Y ... second space.

Claims (5)

In the duct forming the first space surrounded by the outer wall having the fluid inlet, the second space surrounded by the inner partition having the fluid outlet is formed, and the first space and the second space are separated from each other. in the internal partition wall which isolates the fluid spout from the first space communicating with the second space, a by opposing mixing device of the fluid provided over the pair of said second space, said phase counter A fluid mixing apparatus comprising: a nozzle that mixes a fluid having a composition different from that of the fluid in a region where fluid ejected from a fluid ejection port disposed directly collides with and interferes with the fluid. The fluid mixing apparatus according to claim 1, wherein a plurality of sets of the second space and the nozzle are provided in a cross section perpendicular to the fluid flow direction in the duct. When mixing different fluids using the fluid mixing apparatus according to claim 1 or 2, the flow rate or concentration of the fluid mixed from the nozzle is adjusted so that the mixed fluid becomes homogeneous. Control method for fluid mixing device. 4. The fluid mixing according to claim 3, wherein the fluid mixed from the nozzle is an ammonia-containing gas, and the flow rate or ammonia concentration of the ammonia-containing gas mixed from the nozzle is adjusted so that the mixed fluid becomes homogeneous. Device control method. An exhaust gas denitration apparatus comprising a duct having an inlet of exhaust gas containing a nitrogen compound and a denitration apparatus provided at the outlet of the duct, wherein the fluid mixing device according to claim 1 or 2 is provided in the duct. An exhaust gas denitration apparatus characterized by that.

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