Flue denitrification ammonia spraying uniform distribution device and denitrification ammonia spraying system

Abstract

The present invention is a flue denitration ammonia uniform distribution device and a denitration ammonia spraying system, the device comprises an annular distribution pipe and at least two mutually independent ammonia spraying structures; the annular distribution pipe is connected to an ammonia inlet pipeline; a plurality of ammonia spraying structures are uniformly and adjacently arranged in the flue, each ammonia spraying structure is connected to the annular distribution pipe through an ammonia spraying branch pipe, each ammonia spraying structure comprises an I-shaped branch pipe structure, the I-shaped branch pipe structure can be connected to the ammonia spraying branch pipe, a plurality of distributors are connected to the I-shaped branch pipe structure, a plurality of injectors are connected to each distributor, the injection direction of each injector is arranged vertically to the central axis of the injector, and the ammonia gas flow injected by the plurality of injectors connected to each distributor can form a central rotating gas flow. The present invention realizes the optimization of the ammonia spraying device through reasonable arrangement, optimizes the uniform mixing effect of ammonia and flue gas nitrogen oxides, improves the denitration efficiency, and reduces the ammonia escape rate. The operability is strong, the economic benefits of operation are improved, and the actual engineering application can be met.

Description

Technical Field

[0001] The invention relates to the technical field of flue gas or industrial tail gas denitration, and in particular to a flue denitration ammonia spraying uniform distribution device and a denitration ammonia spraying system. Background Art

[0002] The control of air pollution is an important part of environmental governance. With the development of industry and the improvement of living standards, people are paying more and more attention to environmental issues and atmospheric environmental protection issues.

[0003] Nitrogen oxides (NOx) are a major type of air pollutant that contributes to acid rain, photochemical smog, and PM. 2.5 One of the main factors of pollution. At present, NOx emissions from industrial sources in my country account for more than 70% of the total NOx emissions. The control emission technologies for NOx in industrial flue gas mainly include combustion control technology and post-combustion control technology. Combustion control technology includes low-nitrogen combustion technology, reburning technology and flue gas recirculation technology. Among the post-combustion control technologies, selective catalytic reduction (SCR), selective non-catalytic reduction (SNCR) and SCR-SNCR hybrid technology are the main technologies. These technologies were first applied in Japan. Considering economic and technical benefits, selective catalytic reduction is the most effective NOx post-control technology.

[0004] my country's energy structure is mainly based on coal. During the coal burning process, a large amount of air pollutants such as SO2 and NOx are produced, causing serious air pollution and economic losses. There are various pollutants in the flue gas emitted by thermal power, steel and other industries. The newly promulgated flue gas emission standards for thermal power, steel and other industries have put forward strict requirements for NOx emissions. The purpose of denitrification is mainly to remove nitrogen monoxide (NO) and nitrogen dioxide (NO2). The proportion of nitrogen monoxide (NO) to nitrogen oxides (NOx) in flue gas is very high, often more than 90%.

[0005] Nitric oxide is a pollutant gas. When it is directly discharged into the atmosphere, it is easy to pollute the atmosphere, soil and water sources. Therefore, when factories discharge flue gas, especially when the flue gas contains nitric oxide, they need to denitrify the flue gas. Among them, the existing flue gas denitrification technologies mainly include dry method and wet method. Compared with wet flue gas denitrification technology, the main advantages of dry flue gas denitrification technology are: low basic investment, simple equipment and process, and removal of NO X The efficiency is also high, there is no wastewater and waste treatment, and it is not easy to cause secondary pollution.

[0006] Among the removal of SO2 and NOx, the removal of NOx is much more difficult than that of SO2. Therefore, from the perspective of NOx, the simultaneous desulfurization and denitrification technologies can be roughly divided into two categories. The first category is the catalytic reduction method, which mainly uses catalysts, reducing agents, etc. to reduce NOx to achieve simultaneous desulfurization and denitrification; the second category is the oxidation absorption method, which mainly uses various strong oxidants and active free radicals to oxidize water-insoluble NO to generate NO2, and SO2 and NO2 are subsequently absorbed simultaneously. Strong oxidants include NaClO2, ClO2, HClO3, KMnO4, H2O2, etc. Free radicals include O2 - OH - , O3, etc. Its production technologies include electron beam technology, pulsed corona discharge, and free radical cluster lamp. Nitric oxide is difficult to remove, while nitrogen dioxide is easier to remove. Therefore, the technology to convert nitric oxide into nitrogen dioxide is more critical.

[0007] At present, the desulfurization and denitrification technologies widely used at home and abroad include a combination of wet limestone and gypsum flue gas desulfurization (FGD), NH3 selective catalytic reduction denitrification technology (SCR), and activated carbon adsorption catalysis.

[0008] Selective catalytic reduction (SCR) denitrification is to use ammonia, CO or hydrocarbons as reducing agents in the presence of a catalyst to reduce NO in flue gas to N2 in the presence of oxygen. NH3, CO, H2, methane, ethylene, propane, propylene, etc. can be used as reducing agents for SCR reactions. Among them, the highest NO removal efficiency can be achieved when ammonia is used as the reducing gas.

[0009] Among them, SCR is widely used in denitrification of coal-fired power plants, which requires a temperature window of 300-400°C. NOx is reduced to N2 under the action of catalyst and NH3, and the denitrification efficiency can reach more than 90%; the activated carbon adsorption catalytic method utilizes the adsorption and catalytic effects of activated carbon. The application temperature is around 200°C, and the denitrification efficiency is about 50-70% under ammonia spraying conditions; in the field of low-temperature denitrification, SCR needs to heat the flue gas, and the cost of activated carbon technology is relatively high.

[0010] Although the above-mentioned technologies have high desulfurization and denitrification efficiencies, their investment and operating costs are expensive. In addition, the catalysts in the SCR denitrification process have stringent requirements on process conditions, including flue gas temperature and dust characteristics in the flue gas. In addition, the catalysts are easily poisoned and fail, resulting in high operating costs for the SCR system.

[0011] For the selective catalytic reduction method, the two performance parameters of denitrification efficiency and ammonia escape rate are mainly improved through two means: 1. Improving the catalytic reduction ability of the catalyst; 2. Improving the uniformity of the flue gas distribution at the inlet of the catalyst layer and NOx / NH3 (NOx represents nitrogen oxides, NH3 represents ammonia).

[0012] The catalytic reduction capacity of the catalyst is mainly improved by improving the catalyst formula and increasing the amount of catalyst used; while the flue gas distribution at the catalyst layer inlet and the uniformity of NOx / NH3 are achieved by optimizing the flue guide plate of the denitrification device and adjusting the design of the ammonia injection grid. Among them, the ammonia injection grid is particularly critical to the uniform distribution of NOx / NH3 in the flue gas of the denitrification device.

[0013] In the SCR flue gas denitrification system, the injection and mixing of the reducing agent ammonia is an important part of the whole system. Usually, ammonia injection and mixing adopts ammonia spray grid or static mixer to achieve the purpose of uniform mixing of ammonia and flue gas. In the design of the denitrification system, the full mixing of ammonia and nitrogen oxides is a key factor. Uneven mixing will result in a lower denitrification rate or a higher amount of ammonia escape. The effect of this mixing is only an extensive control, and the distribution of ammonia is obviously uneven, which makes it impossible to perform local control and fine tuning.

[0014] However, at present, the flue gas distribution in the denitrification reactor basically adopts the distribution grid inside the reactor, which leads to uneven distribution of flue gas in the denitrification reactor, dead corners in the flue gas distribution in the denitrification reactor, and uneven mixing with ammonia, resulting in low catalytic reaction efficiency and affecting the denitrification efficiency.

[0015] In the existing SCR denitration system, the exhaust gas flue is mostly rectangular. The reducing agent ammonia / air mixed gas is injected into the flue through the ammonia injection grid (AIG) and mixed with the exhaust gas before entering the SCR denitration reactor. The ammonia injection grid is arranged into a rectangular structure according to the flue form, and is distributed by a main pipe and branch pipes. Due to structural reasons, the rectangular ammonia injection grid makes it impossible to control the ammonia injection amount and ammonia injection position, resulting in uneven mixing of the reducing agent ammonia and the flue gas, which in turn affects the denitration efficiency in the denitration reactor and causes excessive ammonia escape from the tail gas after denitration. Some flues with circular cross-sections use multiple injection branch pipes to open holes, which cannot achieve accurate control of the local ammonia injection amount. At the same time, there is a large deviation in the ammonia flow rate of each injection hole, which cannot meet the needs of dynamic control of the local ammonia injection amount caused by uneven flue gas distribution.

[0016] The commonly used ammonia injection grid in the prior art is composed of multiple parallel ammonia injection pipes, each of which is provided with a number of ammonia nozzles. In actual industrial production, the ammonia injection amount of different ammonia nozzles on different ammonia injection pipes varies greatly. In addition, due to the influence of comprehensive factors such as the resistance along the pipeline and the uneven distribution of flue gas velocity in the flue cross section, the distribution of ammonia in the flue cross section is extremely uneven, which seriously affects the denitrification efficiency and increases the ammonia escape rate.

[0017] The common ammonia injection device configuration type of the current SCR denitrification device is a uniformly distributed ammonia injection grid. The basic principle is to design and plan several partitions of the same size in the denitrification inlet flue, and evenly arrange multiple groups of nozzles in the partitions. Each partition corresponds to an ammonia injection branch pipe, and a valve is configured on the ammonia injection branch pipe for manual adjustment.

[0018] However, with the continuous improvement of national environmental protection requirements, the requirements for ultra-clean and even ultra-ultra-clean flue gas denitrification have been put forward. When the flue gas denitrification device requires a denitrification efficiency greater than 90%, simply increasing the amount of catalyst can no longer further improve the efficiency. Higher requirements must be put forward for the uniformity of NOx / NH3. NH3 / NO X The molar ratio distribution deviation needs to be ±3% or even smaller.

[0019] Faced with this high NH3 / NO X The molar ratio distribution deviation requirement, the current ammonia injection grid type begins to expose its shortcomings:

[0020] 1. When faced with some situations where the flue gas flow field has large deviations, the ammonia flow rate required by several local injection branches is too large or too small, exceeding the adjustment range; resulting in the local injection ammonia flow rate being too large or too small relative to the flue gas flow rate, resulting in low denitrification efficiency.

[0021] 2. Ammonia is unevenly distributed on the cross section, and dynamic regulation of local ammonia flow cannot be achieved; the valve of the ammonia injection branch pipe uses an ordinary stop valve, which has poor regulation performance and cannot meet the regulation accuracy requirements.

[0022] 3. The flow distribution of each nozzle on a single branch pipe is uneven. The air flow velocity is higher near the branch pipe inlet and the flow is larger. The gas flow velocity at the end of the branch pipe is slow and the gas volume is insufficient.

[0023] 4. Flue gas and ammonia are not mixed well under laminar and turbulent conditions.

[0024] 5. The setting of spoilers increases the resistance loss of airflow, the equipment is difficult to manufacture, the installation accuracy is high, and the maintenance and repair are inconvenient.

[0025] 6. The use of tapered branch pipes is only applicable to gas distribution under a certain flow condition. The gas flow distribution under different flow conditions is still uneven. The branch pipe processing and manufacturing is difficult and requires high precision.

[0026] The increase of ammonia escape rate will not only reduce the denitration efficiency, but also cause the blockage and corrosion of the denitration device. Therefore, a new ammonia injection grid with reasonable design and suitable application is urgently needed to ensure the uniform mixing of ammonia and nitrogen oxides in the flue, further improve the denitration efficiency, and reduce the ammonia escape rate.

[0027] Therefore, the inventor, relying on his many years of experience and practice in related industries, proposes a flue denitrification ammonia spraying uniform distribution device and a denitrification ammonia spraying system to overcome the defects of the prior art. Summary of the invention

[0028] The purpose of the present invention is to provide a flue denitration ammonia spraying uniform distribution device and a denitration ammonia spraying system, which overcomes the problems existing in the prior art. The present invention can divide the flue cross section into several identical areas, optimize the ammonia spraying device through reasonable arrangement, use the nozzle to form a swirl effect, optimize the uniform mixing effect of ammonia and flue gas nitrogen oxides, improve the denitration efficiency, and reduce the ammonia escape rate. It has strong operability, improves the economic benefits of operation, and can meet the actual engineering application.

[0029] The objective of the present invention is achieved in this way. A flue denitrification ammonia uniform distribution device comprises an annular distribution pipe and at least two independent ammonia spraying structures; the annular distribution pipe is arranged in a ring outside the flue, and the annular distribution pipe is connected to an ammonia inlet pipe; a plurality of ammonia spraying structures are evenly and adjacently arranged in the flue, each of the ammonia spraying structures is connected to the annular distribution pipe through an ammonia spraying branch pipe, each of the ammonia spraying structures comprises an I-shaped branch pipe structure, the I-shaped branch pipe structure can be connected to the ammonia spraying branch pipe, a plurality of distributors are connected to the I-shaped branch pipe structure, a plurality of injectors are connected to each of the distributors, the injection direction of each of the injectors is arranged perpendicular to the central axis of the injector, and the ammonia gas flow injected by the plurality of injectors connected to each of the distributors can form a central rotating gas flow.

[0030] In a preferred embodiment of the present invention, each of the injectors includes a connecting pipe, a first end of the connecting pipe is connected to the distributor, a second end of the connecting pipe is connected to the vertical pipe through a transition pipe, an arc guide plate is provided at one end of the vertical pipe away from the transition pipe, a plurality of through injection holes are evenly arranged along the circumferential direction on the side wall of the vertical pipe, a central axis of the vertical pipe constitutes the central axis of the injector, and the central axis of the injection hole is perpendicular to the central axis of the vertical pipe.

[0031] In a preferred embodiment of the present invention, the I-shaped branch pipe structure includes a plurality of first-level I-shaped branch pipes, each of the first-level I-shaped branch pipes includes a first-level central pipe, both ends of the first-level central pipe are respectively connected to a first-level transverse branch pipe, a first inlet is arranged at the symmetry center of the first-level central pipe, and both ends of each of the first-level transverse branch pipes are respectively arranged with a first outlet, the first inlet can be connected to the ammonia injection branch pipe, and each of the first outlets is respectively connected to a distributor; the distributor is arranged in an X-shape, a second inlet is arranged at the symmetry center of the distributor, the second inlet is connected to the first outlet, second outlets are respectively arranged at each end of the distributor, and each of the second outlets is respectively connected to an injector.

[0032] In a preferred embodiment of the present invention, four second outlets are respectively arranged on each of the distributors, and each of the second outlets is respectively connected to an injector, and the central horizontal line of the four injectors on each of the distributors forms a rectangle, and one group of opposite sides is set as the first reference line, and the other group of opposite sides is set as the second reference line; four through injection holes are evenly arranged on the side wall of the vertical tube along the circumferential direction, and one injection hole is set as the first injection hole, and the injection hole adjacent to the first injection hole is set as the second injection hole, the central axis of the first injection hole is set at a first angle to the first reference line, and the central axis of the second injection hole is set at a second angle to the second reference line, and the first angle and the second angle are set equally.

[0033] In a preferred embodiment of the present invention, the first angle ranges from 10° to 80°, and the second angle ranges from 10° to 80°.

[0034] In a preferred embodiment of the present invention, the diameter of the connecting pipe is smaller than the diameter of the vertical pipe, the transition pipe is a tapered pipe, and the diameter of the transition pipe increases gradually from bottom to top.

[0035] In a preferred embodiment of the present invention, the I-shaped branch pipe structure includes three first-level I-shaped branch pipes, and the I-shaped branch pipe structure also includes a transition connecting pipe, and three third outlets are arranged on the transition connecting pipe, and each of the third outlets is respectively connected to the first inlet of the three first-level I-shaped branch pipes; the transition connecting pipe is provided with a third inlet, and the third inlet is connected to the ammonia injection branch pipe.

[0036] In a preferred embodiment of the present invention, the I-shaped branch pipe structure includes four first-level I-shaped branch pipes, and the I-shaped branch pipe structure also includes a second-level I-shaped branch pipe, a fourth inlet is arranged at the symmetry center of the second-level I-shaped branch pipe, and a fourth outlet is arranged at each end of the second-level I-shaped branch pipe, the fourth inlet is connected to the ammonia injection branch pipe, and each fourth outlet is connected to each first inlet.

[0037] In a preferred embodiment of the present invention, each of the ammonia injection branch pipes is provided with a first regulating valve and a flow meter.

[0038] In a preferred embodiment of the present invention, the annular distribution pipe is connected to at least two of the ammonia inlet pipes, and the two ammonia inlet pipes are designed with a symmetrical structure; the cross-sectional area of ​​the annular distribution pipe is greater than twice the sum of the cross-sectional areas of each of the ammonia injection branch pipes; and a second regulating valve is provided on each of the ammonia inlet pipes.

[0039] The object of the present invention can also be achieved in this way. A denitrification ammonia injection system includes a flue before denitrification, a flue for denitrification treatment and a control system. The first end of the flue before denitrification is provided with a flue gas inlet, the first end of the flue for denitrification treatment is provided with a flue gas outlet, the second end of the flue before denitrification and the second end of the flue for denitrification treatment are arranged in a sealed communication; a heat exchanger is arranged in communication with the flue before denitrification and the flue for denitrification treatment; an SCR denitrification reactor is arranged between the second end of the flue for denitrification treatment and the heat exchanger; and a flue before denitrification is provided between the second end of the flue for denitrification treatment and the heat exchanger. At least one of the aforementioned flue denitrification ammonia spraying uniform distribution devices is provided, and the flue denitrification ammonia spraying uniform distribution device is arranged perpendicularly to the central axis of the flue before denitrification; a swirl mixing structure is arranged between the flue denitrification ammonia spraying uniform distribution device and the heat exchanger; an ammonia analyzer is arranged between the heat exchanger and the SCR denitrification reactor, and the ammonia analyzer is used to detect the amount of ammonia in the flue gas after denitrification treatment by the SCR denitrification reactor, and the ammonia analyzer is provided with a plurality of sampling and measuring points, and each of the sampling and measuring points is arranged in one-to-one correspondence with each distributor of the flue denitrification ammonia spraying uniform distribution device.

[0040] In a preferred embodiment of the present invention, two flue denitrification ammonia spraying distribution devices are arranged axially parallel and spaced apart on the flue before denitrification, between the second end thereof and the heat exchanger, each of the flue denitrification ammonia spraying distribution devices comprises an annular distribution pipe and at least two independent ammonia spraying structures; each of the ammonia spraying structures comprises an I-shaped branch pipe structure, the I-shaped branch pipe structure comprises a plurality of first-level I-shaped branch pipes, each of the first-level I-shaped branch pipes comprises a first-level central pipe and a first-level transverse branch pipe, and the circumferential angle between the first-level central pipes of the two flue denitrification ammonia spraying distribution devices is the third angle.

[0041] In a preferred embodiment of the present invention, the third angle ranges from 30° to 60°.

[0042] In a preferred embodiment of the present invention, the cyclone mixing structure includes a plurality of cyclone mixers arranged adjacent to each other, the plurality of cyclone mixers are connected to the flue before denitrification through a fixed structure, and a center line connecting three adjacent cyclone mixers forms an equilateral triangle.

[0043] In a preferred embodiment of the present invention, each of the swirl mixers comprises an annular frame, a connecting ring is coaxially and radially spaced apart inside the annular frame, a plurality of inclined first swirl blades are circumferentially spaced apart between the annular frame and the connecting ring, and the fourth angle between each of the first swirl blades and the central axis of the connecting ring is set equally.

[0044] In a preferred embodiment of the present invention, the number of the first swirl blades in each of the swirl mixers is 3 to 15, and the fourth angle is in the range of 15° to 70°.

[0045] In a preferred embodiment of the present invention, each of the swirl mixers comprises an annular frame, a connecting ring is coaxially and radially spaced inside the annular frame, a center ring is coaxially and radially spaced inside the connecting ring, a plurality of inclined second swirl blades are circumferentially spaced between the annular frame and the connecting ring, a plurality of inclined third swirl blades are circumferentially spaced between the connecting ring and the center ring, the swirl directions of the third swirl blades and the second swirl blades are oppositely arranged, the fifth angle between each of the second swirl blades and the central axis of the connecting ring is equal, and the sixth angle between each of the third swirl blades and the central axis of the connecting ring is equal.

[0046] In a preferred embodiment of the present invention, the number of the second swirl blades in each of the swirl mixers is 6 to 36, and the range of the fifth angle is 25° to 70°; the number of the third swirl blades in each of the swirl mixers is 3 to 24, and the range of the sixth angle is 15° to 65°.

[0047] As described above, the flue denitration ammonia spraying uniform distribution device and the denitration ammonia spraying system provided by the present invention have the following beneficial effects:

[0048] (1) In the flue denitration ammonia uniform distribution device provided by the present invention, multiple independent ammonia injection structures divide the flue into several independent ammonia injection areas, realize independent control of the ammonia injection amount by area, meet the requirements of different ammonia injection amounts due to uneven flue gas distribution in different areas, and eliminate the phenomenon that the local ammonia concentration of the traditional ammonia injection grid is too large, causing the ammonia escape amount to exceed the standard; each area is provided with an I-shaped branch pipe structure, a distributor and an injector, and each ammonia injection branch pipe is provided with a first regulating valve and a flow meter, and the ammonia injection amount of each area can be adjusted and controlled by the first regulating valve and the flow meter, so that the ammonia injection amount can be adjusted by area on the flue cross section, optimize the uniform mixing effect of ammonia and nitrogen oxides in the air, improve the denitration efficiency, and effectively reduce the ammonia escape rate; the distribution pipe is arranged in a ring shape, which can not only ensure the uniformity of ammonia injection, but also effectively prevent blockage and corrosion;

[0049] (2) In the flue denitration ammonia uniform distribution device provided by the present invention, each ammonia injection structure adopts an I-shaped branch pipe structure, a distributor and an injector connection method, so that the resistance loss along the way of all injectors is equal, and the flow rate and pressure of each injector in each ammonia injection area are equal, eliminating the difference between each injector, achieving uniform distribution of ammonia injection amount in the partition, and eliminating the large flow unevenness between traditional ammonia injection grid injectors;

[0050] (3) In the flue denitration ammonia uniform distribution device provided by the present invention, the distributors in each partition are arranged in an X-shape, and an injector is arranged at the end of the distributor, so that in each partition, all injectors can achieve equal injector spacing in the horizontal and vertical directions, achieve uniform distribution of the injectors, achieve equal coverage of the areas by each injector, and achieve uniform distribution of the amount of ammonia injected by each injector in space; the injector is used to form a swirl effect, optimize the uniform mixing effect of ammonia and nitrogen oxides in the flue gas, improve the denitration efficiency, and reduce the ammonia escape rate;

[0051] (4) In the denitration ammonia spraying system provided by the present invention, a flue denitration ammonia spraying uniform distribution device is provided. Since the distribution of flue gas in the flue is not uniform, there are local areas with large flue gas flow rates. A flue gas velocity measuring instrument, a flue gas analyzer and an ammonia analyzer are used to calculate the nitrogen oxide load according to the flue gas flow rate for the ammonia spraying partition corresponding to the local area with large flue gas flow rate, and the required ammonia spraying amount is calculated according to the nitrogen oxide load of the partition. The ammonia spraying amount of the partition is adjusted and the flow rate is monitored according to the required ammonia spraying amount, so as to realize automatic setting, automatic adjustment and automatic detection of the ammonia spraying amount in each area, realize dynamic control of the ammonia spraying amount, realize ideal nitrogen oxide removal, meet the requirement of being able to adjust the ammonia spraying amount in real time under different flue gas working conditions, and monitor the residual ammonia amount in the flue gas at the same time to avoid excessive ammonia escape in the discharged flue gas;

[0052] (5) The denitration ammonia injection system provided by the present invention can be modified on the basis of the original denitration system, saving investment and reducing costs while ensuring a high denitration efficiency;

[0053] (6) In the denitration ammonia spraying system provided by the present invention, the flue denitration ammonia spraying uniform distribution device has a simple structure and is easy to adjust. The ammonia and flue gas are mixed more evenly, thereby improving the removal efficiency of nitrogen oxides;

[0054] (7) The present invention is simple and convenient to manufacture and install, and is easy to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] The following drawings are only intended to illustrate and explain the present invention, and are not intended to limit the scope of the present invention.

[0056] in:

[0057] Figure 1 : It is a schematic diagram of the flue denitrification ammonia uniform distribution device of the present invention.

[0058] Figure 2 : is the structural diagram of the ejector of the present invention.

[0059] Figure 3 :for Figure 2 Center A view.

[0060] Figure 4:for Figure 2 Middle BB section view.

[0061] Figure 5 : is the structural diagram of the distributor of the present invention.

[0062] Figure 6 :for Figure 5 Middle CC section view.

[0063] Figure 7 : It is a schematic diagram of ammonia injection by multiple injectors on a distributor of the present invention.

[0064] Figure 8 : is a schematic diagram of a primary I-shaped branch pipe connecting a distributor according to the present invention.

[0065] Fig. 9 : It is a structural diagram of the ammonia injection structure of the present invention including a combination of three primary I-shaped branch pipes.

[0066] Fig.10 : It is a structural diagram of the ammonia injection structure of the present invention including a combination of 4 first-level I-shaped branch pipes.

[0067] Fig.11 : It is a structural schematic diagram of the denitration ammonia injection system of the present invention.

[0068] Fig.12 :for Fig.11 Middle DD section view.

[0069] Fig.13 :for Fig.11 EE section view.

[0070] Fig.14 :for Fig.11 Enlarged view of point I in the middle.

[0071] Fig.15 : is a top view of the swirl mixing structure of the present invention.

[0072] Fig.16 : is the layout diagram of three cyclone mixers in the cyclone mixing structure of the present invention.

[0073] Fig.17 : is a top view of a specific embodiment of the cyclone mixer of the present invention.

[0074] Fig.18 : is a front view of a specific embodiment of a cyclone mixer of the present invention.

[0075] Fig.19 : is a top view of another specific embodiment of the cyclone mixer of the present invention.

[0076] Fig. 20: is a front view of another specific embodiment of the cyclone mixer of the present invention.

[0077] In the figure:

[0078] 200. Denitrification ammonia injection system;

[0079] 100. Flue denitrification ammonia spraying uniform distribution device;

[0080] 1. Annular distribution pipe;

[0081] 2. Ammonia spraying structure;

[0082] 3. Ammonia inlet pipeline; 31. Second regulating valve;

[0083] 4. Ammonia injection branch pipe; 41. First regulating valve; 42. Flow meter;

[0084] 5. Distributor;

[0085] 6. Injector;

[0086] 61. connecting pipe; 62. transition pipe; 63. vertical pipe; 64. arc guide plate; 65. injection hole; 651. first injection hole; 652. second injection hole;

[0087] 7. I-shaped branch pipe structure;

[0088] 71, first-level I-shaped branch pipe; 711, first-level central pipe; 712, first-level horizontal branch pipe;

[0089] 72. Secondary I-shaped branch pipe;

[0090] 73. Transition connecting pipe;

[0091] 8. Swirl mixing structure;

[0092] 81. swirl mixer; 811. annular frame; 812. connecting ring; 813. first swirl blade; 814. center ring; 815. second swirl blade; 816. third swirl blade;

[0093] 82. Fixed structure;

[0094] 91. Flue duct before denitrification; 911. Flue gas inlet; 92. Flue duct for denitrification treatment; 921. Flue gas outlet; 93. Heat exchanger; 94. SCR denitrification reactor; 95. Flue gas analyzer; 96. Flue gas velocity measuring instrument; 97. Spoiler; 98. Flame burner; 99. Ammonia analyzer. DETAILED DESCRIPTION

[0095] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described with reference to the accompanying drawings.

[0096] The specific embodiments of the present invention described herein are only used to explain the purpose of the present invention and cannot be understood as limiting the present invention in any way. Under the guidance of the present invention, technicians can conceive of any possible variations based on the present invention, which should be considered to belong to the scope of the present invention. It should be noted that when an element is referred to as "arranged on" another element, it can be directly on the other element or there can also be a central element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be a central element at the same time. The terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a mechanical connection or an electrical connection, or it can be the internal communication of two elements, it can be directly connected, or it can be indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to the specific circumstances. The terms "vertical", "horizontal", "up", "down", "left", "right" and similar expressions used herein are only for illustrative purposes and do not represent the only implementation method.

[0097] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0098] The present invention relates to a selective catalytic reduction flue gas denitration system for coal-fired, oil-fired and gas-fired power plants, and the injection and mixing application technology of ammonia gas, a denitration reducing agent, and is applicable to the denitration of flue gas or industrial tail gas in power plants, thermal power plants, metallurgy, chemical industry, feed and other industries.

[0099] like Figures 1 to 10 As shown, the present invention provides a flue denitration ammonia uniform distribution device 100, comprising an annular distribution pipe 1 and at least two independent ammonia spraying structures 2; the annular distribution pipe 1 is arranged in a ring outside the flue, and the annular distribution pipe 1 is connected to an ammonia inlet pipe 3; a plurality of ammonia spraying structures 2 are evenly and adjacently arranged in the flue, each ammonia spraying structure 2 is connected to the annular distribution pipe 1 through an ammonia spraying branch pipe 4, each ammonia spraying structure 2 comprises an I-shaped branch pipe structure, the I-shaped branch pipe structure can be connected to the ammonia spraying branch pipe 4, a plurality of distributors 5 are connected to the I-shaped branch pipe structure, each distributor 5 is connected to a plurality of injectors 6, the injection direction of each injector 6 is perpendicular to the central axis of the injector, and the ammonia gas flow injected by the plurality of injectors connected to each of the distributors can form a central rotating gas flow.

[0100] In the flue denitration ammonia uniform distribution device provided by the present invention, a plurality of mutually independent ammonia spraying structures divide the flue into a plurality of independent ammonia spraying areas, and the distribution pipe is arranged in a ring shape, which can ensure the uniformity of ammonia spraying and effectively prevent blockage and corrosion;

[0101] Each ammonia injection structure adopts an I-shaped branch pipe structure, a distributor and an injector connection method, so that the resistance loss along the way of all injectors is equal, and the flow rate and pressure of each injector in each ammonia injection area are equal, eliminating the difference between each injector, achieving uniform distribution of ammonia injection amount in the partition, and eliminating the large flow unevenness between traditional ammonia injection grid injectors;

[0102] The ejector is used to form a swirl effect, optimize the uniform mixing of ammonia and nitrogen oxides in the flue gas, improve the denitrification efficiency, and reduce the ammonia escape rate.

[0103] Further, if Figure 2 , Figure 3 , Figure 4 As shown, each injector 6 includes a connecting pipe 61, a first end of the connecting pipe 61 is connected to the distributor 5, and a second end of the connecting pipe 61 is connected to the vertical pipe 63 through a transition pipe 62. An arc-shaped guide plate 64 is provided at one end of the vertical pipe 63 away from the transition pipe 62, and the arc-shaped surface of the arc-shaped guide plate 64 away from the vertical pipe 63 is opposite to the flow direction of the flue gas. Figure 2 A direction is the flue gas flow direction. Multiple through-spray holes 65 are evenly arranged on the side wall of the vertical tube 63 along the circumferential direction. The central axis of the vertical tube 63 constitutes the central axis of the injector, and the central axis of the spray hole is arranged perpendicular to the central axis of the vertical tube. The flue is arranged vertically, the flue denitration ammonia spraying uniform distribution device 100 is arranged horizontally, and the central axis of the spray hole is arranged horizontally. The spray direction of each injector 6 is as follows: Figure 4 Indicated by the direction of the arrow.

[0104] In the flue denitrification ammonia uniform distribution device provided by the present invention, the injection hole of each injector is perpendicular to the axial direction of the flue, and an arc-shaped guide plate is arranged at the free end of the injector to achieve uniform diffusion distribution of the airflow. The arc-shaped guide plate promotes uniform mixing of flue gas and ammonia and reduces scouring and wear of the injector by flue gas.

[0105] Further, if Figure 8As shown, the I-shaped branch pipe structure 7 includes a plurality of first-level I-shaped branch pipes 71, each of which includes a first-level central pipe 711, and both ends of the first-level central pipe 711 are respectively connected to a first-level transverse branch pipe 712, a first inlet is arranged at the symmetric center of the first-level central pipe 711, and both ends of each first-level transverse branch pipe 712 are respectively arranged with a first outlet, the first inlet can be connected to the ammonia injection branch pipe 4, and each first outlet is respectively connected to a distributor 5; the distributor 5 is arranged in an X-shape, a second inlet is arranged at the symmetric center of the distributor 5, the second inlet is connected to the first outlet, and each end of the distributor 5 is respectively provided with a second outlet, and each second outlet is respectively connected to an injector 6.

[0106] like Figure 5 , Figure 6 As shown, the distributor 5 is arranged in an X shape, and an injector 6 is arranged at the end of the distributor 5. All injectors can achieve equal injector spacing in the horizontal and vertical directions, achieve uniform distribution of the injectors, achieve equal areas covered by each injector, and achieve uniform distribution of the amount of ammonia injected by each injector in space.

[0107] Further, if Figure 7 As shown, four second outlets are respectively arranged on each distributor 5, and each second outlet is connected to an injector respectively. The central horizontal line of the four injectors on each distributor forms a rectangle, and one group of opposite sides is set as the first reference line, and the other group of opposite sides is set as the second reference line; four through injection holes 65 are evenly arranged on the side wall of the vertical tube along the circumferential direction, one injection hole is set as the first injection hole 651, and the injection hole adjacent to the first injection hole is set as the second injection hole 652. The central axis of the first injection hole 651 is set at a first angle α with the first reference line, and the central axis of the second injection hole 652 is set at a second angle β with the second reference line, and the first angle α and the second angle β are set equally.

[0108] Further, the first angle α is in the range of 10° to 80°, preferably in the range of 15° to 30° and 60° to 75°; the second angle β is in the range of 10° to 80°, preferably in the range of 15° to 30° and 60° to 75°. The value ranges of the first angle α and the second angle β directly affect the rotation direction of the central rotating airflow, which can be clockwise or counterclockwise.

[0109] Furthermore, the diameter of the connecting pipe 61 is smaller than the diameter of the vertical pipe 63 , and the transition pipe 62 is a tapered pipe, and the diameter of the transition pipe 62 is gradually increased from bottom to top.

[0110] Furthermore, the ammonia spraying structure 2 may be a combination of three first-level I-shaped branch pipes 71, or a combination of four first-level I-shaped branch pipes 71 and one second-level I-shaped branch pipe 72. The flue denitrification ammonia spraying uniform distribution device 100 may perform different ammonia spraying structure combinations according to the flue cross-sectional dimensions to achieve uniform distribution of ammonia spraying units in the flue.

[0111] like Fig. 9 As shown, in a specific embodiment of the present invention, the I-shaped branch pipe structure includes three first-level I-shaped branch pipes 71, and the I-shaped branch pipe structure 7 also includes a transition connecting pipe 73, and three third outlets are arranged on the transition connecting pipe 73, and each third outlet is respectively connected to the first inlet of the three first-level I-shaped branch pipes 71; the third inlet is arranged on the transition connecting pipe 73, and the third inlet is connected to the ammonia injection branch pipe 4.

[0112] like Fig.10 As shown, in another embodiment of the present invention, the I-shaped branch pipe structure includes four primary I-shaped branch pipes 71, and the I-shaped branch pipe structure 7 also includes a secondary I-shaped branch pipe 72. A fourth inlet is arranged at the symmetric center of the secondary I-shaped branch pipe 72, and a fourth outlet is arranged at each end of the secondary I-shaped branch pipe 72. The fourth inlet is connected to the ammonia injection branch pipe 4, and each fourth outlet is connected to each first inlet. The primary I-shaped branch pipe 71 is connected to four distributors, and the distance between an injector and two adjacent injectors (adjacent along the length direction of the primary central pipe 711 and along the length direction of the primary horizontal branch pipe 712, respectively) is d, and the preferred range of the distance d is 200-800 mm.

[0113] Further, if Figure 1 As shown, each ammonia injection branch pipe 4 is provided with a first regulating valve 41 and a flow meter 42. The first regulating valve 41 and the flow meter 42 can be used to adjust and control the ammonia injection amount of each ammonia injection structure 2, so that the ammonia injection amount can be adjusted in different zones on the flue cross section, optimizing the uniform mixing effect of ammonia and nitrogen oxides in the air, improving the denitrification efficiency, and effectively reducing the ammonia escape rate.

[0114] Furthermore, the annular distribution pipe 1 is connected to at least two ammonia inlet pipes 3, and the two ammonia inlet pipes 3 adopt a symmetrical structure design; the annular distribution pipe 1 adopts a circular ring pipeline design, and the cross-sectional area of ​​the annular distribution pipe 1 is greater than twice the sum of the cross-sectional areas of all ammonia injection branch pipes 4, so as to achieve a uniform and stable ammonia flow rate in each ammonia injection branch pipe 4; a second regulating valve 31 is provided on the ammonia inlet pipe 3 to adjust the ammonia intake amount.

[0115] In this embodiment, the annular distribution pipe 1 and the ammonia injection branch pipe 4 are connected via a flange.

[0116] Furthermore, the flue denitration ammonia spraying uniform distribution device 100 further includes a control component connected to the first regulating valve 41 and the second regulating valve 31. The first regulating valve 41 and the second regulating valve 31 in the embodiment of the present invention are both opening regulating valves, including an actuator and an electromagnetic flow regulating valve body, which are used to receive an opening signal from the control component and adjust the opening of the electromagnetic flow regulating valve body to achieve automatic adjustment of the ammonia spraying amount.

[0117] like Figures 11 to 20 As shown, the present invention also provides a denitrification ammonia injection system 200, including a flue 91 before denitrification, a flue 92 for denitrification treatment and a control system (not shown in the figure), a flue 91 before denitrification is provided at the first end of the flue 91 before denitrification, a flue 921 for denitrification treatment is provided at the first end of the flue 92 before denitrification, and the second end of the flue 91 before denitrification and the second end of the flue 92 for denitrification treatment are sealed and connected; a heat exchanger 93 is connected and connected on the flue 91 before denitrification and the flue 92 for denitrification treatment; an SCR denitrification reactor 94 is provided between the second end of the flue 92 for denitrification treatment and the heat exchanger 93; the heat exchanger 93 utilizes the high-temperature flue gas after denitrification with a higher temperature after passing through the SCR denitrification reactor to preheat the low-temperature flue gas before denitrification with a lower temperature before entering the SCR denitrification reactor, thereby making full use of the waste heat and reducing the energy consumption required for heating the flue gas before denitrification.

[0118] At least one flue denitration ammonia spraying uniform distribution device 100 is arranged between the second end of the flue 91 before denitration and the heat exchanger 93, and the flue denitration ammonia spraying uniform distribution device 100 is arranged vertically with the central axis of the flue 91 before denitration; a swirl mixing structure 8 is arranged between the flue denitration ammonia spraying uniform distribution device 100 and the heat exchanger 93; an ammonia analyzer 99 is arranged between the heat exchanger 93 and the SCR denitration reactor 94, and the ammonia analyzer 99 is used to detect the amount of ammonia in the flue gas after the denitration treatment by the SCR denitration reactor. The ammonia analyzer 99 is provided with multiple sampling and measuring points, and each sampling and measuring point is arranged one by one corresponding to each distributor 5 of the flue denitration ammonia spraying uniform distribution device 100.

[0119] A flue gas analyzer 95 and a flue gas velocity measuring instrument 96 are arranged between the heat exchanger 93 and the flue denitration ammonia spraying uniform distribution device 100, and a spoiler 97 and a flame burner 98 are arranged between the flue denitration ammonia spraying uniform distribution device 100 and the second end of the flue 91 before denitration. The flue gas analyzer 95 is used to measure the content of nitrogen oxides in the flue gas, and the flue gas velocity measuring instrument 96 is used to measure the flue gas flow rate in the flue before denitration; the flue gas analyzer 95, the flue gas velocity measuring instrument 96 and the ammonia analyzer 99 are all electrically connected to the control system. The number of the flame burners 98 is greater than or equal to 2, and the flame burners 98 burn combustible gas and combustion-supporting gas to achieve the temperature increase of the flue gas and ammonia, meet the flue gas temperature requirements required for the SCR reaction, and achieve the expected denitration reaction. The spoiler 97 can adopt a V-shaped long groove structure, a groove structure, or a spiral blade structure.

[0120] By using flue gas velocity measuring instruments, flue gas analyzers and ammonia analyzers, the automatic setting, automatic adjustment and automatic detection of the ammonia injection amount in each area can be realized, and the dynamic control of the ammonia injection amount can be realized to meet the requirements of real-time adjustment of the ammonia injection amount under different flue gas working conditions. At the same time, the residual ammonia amount in the flue gas is monitored to avoid excessive ammonia escape in the exhaust gas.

[0121] In the denitration ammonia spraying system provided by the present invention, a flue denitration ammonia spraying uniform distribution device is adopted to divide the cross section of the flue before denitration into a plurality of identical areas, and the optimization of ammonia spraying is realized through reasonable arrangement, which can not only ensure the uniformity of ammonia spraying, but also effectively prevent blockage and corrosion, and utilize the injector to form a swirl effect, optimize the uniform mixing effect of ammonia and flue gas nitrogen oxides, improve the denitration efficiency, and reduce the ammonia escape rate; at the same time, the ammonia introduction amount can be adjusted according to the concentration of nitrogen oxides in the flue gas, the operability is strong, the economic benefit of operation is improved, and the actual engineering application can be met.

[0122] Further, if Fig.14 As shown, two flue denitration ammonia spraying uniform distribution devices 100 are arranged axially parallel and spaced apart on the flue 91 before denitration, and located between the second end thereof and the heat exchanger 93. Each flue denitration ammonia spraying uniform distribution device 100 comprises an annular distribution pipe 1 and at least two ammonia spraying structures 2; each ammonia spraying structure 2 comprises an I-shaped branch pipe structure 7, and the I-shaped branch pipe structure 7 comprises a plurality of first-level I-shaped branch pipes 71, and each first-level I-shaped branch pipe 71 comprises a first-level central pipe 711 and a first-level horizontal branch pipe 712, as shown in FIG. Fig.12 , Fig.13 As shown, the circumferential angle between the primary central tubes of the two flue denitration ammonia spraying uniform distribution devices 100 is the third angle. The primary central tubes of the two flue denitration ammonia spraying uniform distribution devices 100 are arranged at a certain circumferential angle, so that the injectors of each flue denitration ammonia spraying uniform distribution device 100 are circumferentially staggered, so that the ammonia spraying in each independent partition is more uniform.

[0123] The central axis of the annular distribution pipe 1 coincides with the central axis of the flue 91 before denitrification, and each ammonia injection branch pipe 4 seals through the side wall of the flue 91 before denitrification to connect with each ammonia injection structure 2.

[0124] Furthermore, the third angle ranges from 30° to 60°, and the preferred angle is 45°.

[0125] Further, if Fig.15 , Fig.16 As shown, the swirl mixing structure 8 includes a plurality of swirl mixers 81 arranged adjacent to each other, and the plurality of swirl mixers 81 are connected to the pre-denitrification flue 91 through a fixing structure 82, and the center line of three adjacent swirl mixers 81 is an equilateral triangle. The length of the center line is equal to the diameter of the swirl mixer, so as to maximize the swirl action area of ​​the flue gas and reduce the area of ​​the flue gas that cannot be swirled.

[0126] The fixing structure 82 includes a plurality of fixing rods that can be fixedly connected to the flue 91 before denitration, and the distance between adjacent fixing rods is smaller than the diameter of the cyclone mixer 81 .

[0127] Furthermore, the cyclone mixer can be of various structural types.

[0128] like Fig.17 , Fig.18 As shown, in a specific embodiment of the present invention, each swirl mixer 81 includes an annular frame 811, a connecting ring 812 is coaxially and radially spaced inside the annular frame 811, a plurality of inclined first swirl blades 813 are circumferentially spaced between the annular frame 811 and the connecting ring 812, and the fourth angle between each first swirl blade 813 and the central axis of the connecting ring 812 is set equally.

[0129] Furthermore, the number of the first swirl blades 813 in each swirl mixer 81 is 3 to 15, and the fourth angle is in the range of 15° to 70°.

[0130] like Fig.19 , Fig. 20 As shown, in another specific embodiment of the present invention, each swirl mixer 81 includes an annular frame 811, a connecting ring 812 is coaxially and radially spaced in the annular frame 811, a center ring 814 is coaxially and radially spaced in the connecting ring 812, and a blind plate is arranged at the end of the center ring 814. A plurality of inclined second swirl blades 815 are circumferentially spaced between the annular frame 811 and the connecting ring 812, and a plurality of inclined third swirl blades 816 are circumferentially spaced between the connecting ring 812 and the center ring 814. The swirl directions of the third swirl blades 816 and the second swirl blades 815 are oppositely arranged, the fifth angle between each second swirl blade 815 and the central axis of the connecting ring is equal, and the sixth angle between each third swirl blade 816 and the central axis of the connecting ring is equal. The second swirl blade 815 constitutes an outer swirl blade, and the third swirl blade 816 constitutes an inner swirl blade. The inner swirl blade and the outer swirl blade are used to realize the swirl of the flue gas flow, thereby promoting the mixing of the flue gas and ammonia. The blind plate can prevent the airflow from flowing through the center ring, and the flue gas flows through the gap between the swirl plates, thereby promoting the swirl mixing of the flue gas.

[0131] Furthermore, the number of the second swirl blades in each swirl mixer is 6 to 36, and the fifth angle ranges from 25° to 70°; the number of the third swirl blades in each swirl mixer is 3 to 24, and the sixth angle ranges from 15° to 65°.

[0132] Furthermore, the control system includes a flue gas velocity measurement module, a flue gas composition measurement module, an ammonia injection amount calculation module, an ammonia injection amount monitoring module, and a measurement data summary and analysis module; the velocity measurement module is used to measure the flue gas flow rate in each different area in the flue, the flue gas composition analysis module is used to measure the content of nitrogen oxides in the flue gas, and the nitrogen oxide removal load is calculated by a computer program; the measurement data summary and analysis module is used to calculate the nitrogen oxide load according to the flue gas flow and flue gas composition in each area, calculate the ammonia injection amount required for each area according to the nitrogen oxide load, adjust the ammonia injection amount of each area by the first regulating valve 41 (electric or pneumatic) on the ammonia injection branch pipe 4, and monitor the actual ammonia injection amount according to the flow meter 42 on the ammonia injection branch pipe 4; the ammonia monitoring module is used to detect the amount of unreacted ammonia downstream of the SCR denitrification reactor, and feedback control the ammonia injection amount according to the ammonia escape amount in each area. When the ammonia escape amount exceeds the set value, the system prompts that the ammonia injection amount of the corresponding area is too large, and the ammonia injection amount of the area is reduced accordingly to achieve the minimum ammonia consumption and ammonia escape amount.

[0133] The use process of the denitration ammonia injection system 200 of the present invention is as follows:

[0134] The original flue gas (unpurified flue gas before denitration) enters the denitration ammonia spraying system 200 of the present invention through the flue gas inlet 911, and first passes through the heat exchanger 93 to preheat the flue gas. The heated flue gas flows through the flue gas analyzer 95 and the flue gas velocity measuring instrument 96. The flue denitration ammonia spraying uniform distribution device 100 performs ammonia spraying operation, and the injected ammonia is mixed with the flue gas. The flue gas continues to rise and passes through the spoiler 97 for circumferential mixing to promote further mixing of ammonia and flue gas. The combustible gas and The efficient combustion of the combustion-supporting air further increases the temperature of the flue gas and ammonia mixture. The flue gas is further mixed with ammonia through the guiding effect of the turning elbow and the guide plate, and the energy is mixed at the same time to achieve uniform flue gas temperature. The flue gas and ammonia mixture is rectified by the rectifying grid, so that the flue gas and ammonia mixture can enter the catalyst of the SCR denitration reactor evenly and vertically, achieving efficient, rapid and uniform reaction of nitrogen oxides and ammonia in the flue gas under the catalytic effect of the catalyst;

[0135] The flue gas mixture after passing through the catalyst of the SCR denitrification reactor flows through the ammonia analyzer 99, which detects the ammonia content in the mixed gas and controls the ammonia concentration to be lower than the set value. If the ammonia content exceeds the set value, it is fed back to the control system to reset the ammonia injection amount of the flue denitrification ammonia injection distribution device 100. At the same time, the control system controls the first regulating valve to adjust the ammonia injection amount of the ammonia injection structure 2, and continuously monitors the residual ammonia content downstream of the SCR denitrification reactor to meet the set value. The denitrified mixed gas enters the heat exchanger 93 and flows through the flue gas outlet 921 to enter the downstream dust collector (existing technology).

[0136] As described above, the flue denitration ammonia spraying uniform distribution device and the denitration ammonia spraying system provided by the present invention have the following beneficial effects:

[0137] (1) In the flue denitration ammonia uniform distribution device provided by the present invention, multiple independent ammonia injection structures divide the flue into several independent ammonia injection areas, realize independent control of the ammonia injection amount by area, meet the requirements of different ammonia injection amounts due to uneven flue gas distribution in different areas, and eliminate the phenomenon that the local ammonia concentration of the traditional ammonia injection grid is too large, causing the ammonia escape amount to exceed the standard; each area is provided with an I-shaped branch pipe structure, a distributor and an injector, and each ammonia injection branch pipe is provided with a first regulating valve and a flow meter, and the ammonia injection amount of each area can be adjusted and controlled by the first regulating valve and the flow meter, so that the ammonia injection amount can be adjusted by area on the flue cross section, optimize the uniform mixing effect of ammonia and nitrogen oxides in the air, improve the denitration efficiency, and effectively reduce the ammonia escape rate; the distribution pipe is arranged in a ring shape, which can not only ensure the uniformity of ammonia injection, but also effectively prevent blockage and corrosion;

[0138] (2) In the flue denitration ammonia uniform distribution device provided by the present invention, each ammonia injection structure adopts an I-shaped branch pipe structure, a distributor and an injector connection method, so that the resistance loss along the way of all injectors is equal, and the flow rate and pressure of each injector in each ammonia injection area are equal, eliminating the difference between each injector, achieving uniform distribution of ammonia injection amount in the partition, and eliminating the large flow unevenness between traditional ammonia injection grid injectors;

[0139] (3) In the flue denitration ammonia uniform distribution device provided by the present invention, the distributors in each partition are arranged in an X-shape, and an injector is arranged at the end of the distributor, so that in each partition, all injectors can achieve equal injector spacing in the horizontal and vertical directions, achieve uniform distribution of the injectors, achieve equal coverage of the areas by each injector, and achieve uniform distribution of the amount of ammonia injected by each injector in space; the injector is used to form a swirl effect, optimize the uniform mixing effect of ammonia and nitrogen oxides in the flue gas, improve the denitration efficiency, and reduce the ammonia escape rate;

[0140] (4) In the denitration ammonia spraying system provided by the present invention, a flue denitration ammonia spraying uniform distribution device is provided. Since the distribution of flue gas in the flue is not uniform, there are local areas with large flue gas flow rates. A flue gas velocity measuring instrument, a flue gas analyzer and an ammonia analyzer are used to calculate the nitrogen oxide load according to the flue gas flow rate for the ammonia spraying partition corresponding to the local area with large flue gas flow rate, and the required ammonia spraying amount is calculated according to the nitrogen oxide load of the partition. The ammonia spraying amount of the partition is adjusted and the flow rate is monitored according to the required ammonia spraying amount, so as to realize automatic setting, automatic adjustment and automatic detection of the ammonia spraying amount in each area, realize dynamic control of the ammonia spraying amount, realize ideal nitrogen oxide removal, meet the requirement of being able to adjust the ammonia spraying amount in real time under different flue gas working conditions, and monitor the residual ammonia amount in the flue gas at the same time to avoid excessive ammonia escape in the discharged flue gas;

[0141] (5) The denitration ammonia injection system provided by the present invention can be modified on the basis of the original denitration system, saving investment and reducing costs while ensuring a high denitration efficiency;

[0142] (6) In the denitration ammonia spraying system provided by the present invention, the flue denitration ammonia spraying uniform distribution device has a simple structure and is easy to adjust. The ammonia and flue gas are mixed more evenly, thereby improving the removal efficiency of nitrogen oxides;

[0143] (7) The present invention is simple and convenient to manufacture and install, and is easy to implement.

[0144] The above description is only an illustrative embodiment of the present invention and is not intended to limit the scope of the present invention. Any equivalent changes and modifications made by any person skilled in the art without departing from the concept and principle of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A flue denitrification ammonia uniform distribution device, characterized in that: It comprises an annular distribution pipe and at least two mutually independent ammonia spraying structures; the annular distribution pipe is connected to an ammonia inlet pipe; a plurality of ammonia spraying structures are evenly and adjacently arranged in the flue, each of the ammonia spraying structures is connected to the annular distribution pipe through an ammonia spraying branch pipe, each of the ammonia spraying structures comprises an I-shaped branch pipe structure, the I-shaped branch pipe structure can be connected to the ammonia spraying branch pipe, a plurality of distributors are connected to the I-shaped branch pipe structure, a plurality of injectors are connected to each of the distributors, the injection direction of each of the injectors is arranged perpendicular to the central axis of the injector, and the ammonia gas flow injected by the plurality of injectors connected to each of the distributors can form a central rotating gas flow; Each of the injectors comprises a connecting pipe, a first end of the connecting pipe is connected to the distributor, a second end of the connecting pipe is connected to the vertical pipe through a transition pipe, an arc guide plate is arranged at one end of the vertical pipe away from the transition pipe, a plurality of through injection holes are evenly arranged on the side wall of the vertical pipe along the circumferential direction, a central axis of the vertical pipe constitutes a central axis of the injector, and a central axis of the injection hole is arranged perpendicular to the central axis of the vertical pipe; The I-shaped branch pipe structure includes a plurality of first-level I-shaped branch pipes, each of the first-level I-shaped branch pipes includes a first-level central pipe, two ends of the first-level central pipe are respectively connected to a first-level transverse branch pipe, a first inlet is arranged at the symmetric center of the first-level central pipe, and two ends of each of the first-level transverse branch pipes are respectively arranged with a first outlet, the first inlet can be connected to the ammonia injection branch pipe, and each of the first outlets is respectively connected to a distributor; the distributor is arranged in an X-shape, a second inlet is arranged at the symmetric center of the distributor, the second inlet is connected to the first outlet, and each end of the distributor is respectively provided with a second outlet, and each of the second outlets is respectively connected to an injector; Four second outlets are respectively arranged on each of the distributors, and each of the second outlets is connected to an injector, and the central horizontal line of the four injectors on each of the distributors forms a rectangle, and one group of opposite sides is set as the first reference line, and the other group of opposite sides is set as the second reference line; four through-spray holes are evenly arranged on the side wall of the vertical tube along the circumferential direction, and one spray hole is set as the first spray hole, and the spray hole adjacent to the first spray hole is set as the second spray hole, the central axis of the first spray hole is set at a first angle to the first reference line, and the central axis of the second spray hole is set at a second angle to the second reference line, and the first angle and the second angle are set equal; The I-shaped branch pipe structure includes three first-level I-shaped branch pipes, and the I-shaped branch pipe structure also includes a transition connecting pipe, and three third outlets are arranged on the transition connecting pipe, and each of the third outlets is respectively connected to the first inlet of the three first-level I-shaped branch pipes; the transition connecting pipe is provided with a third inlet, and the third inlet is connected to the ammonia injection branch pipe; or, The I-shaped branch pipe structure includes four first-level I-shaped branch pipes, and the I-shaped branch pipe structure also includes a second-level I-shaped branch pipe. A fourth inlet is arranged at the symmetry center of the second-level I-shaped branch pipe, and a fourth outlet is arranged at each end of the second-level I-shaped branch pipe. The fourth inlet is connected to the ammonia injection branch pipe, and each fourth outlet is connected to each first inlet.

2. The flue denitration ammonia uniform distribution device according to claim 1, characterized in that: The first angle ranges from 10° to 80°, and the second angle ranges from 10° to 80°.

3. The flue denitration ammonia uniform distribution device according to claim 1, characterized in that: The diameter of the connecting pipe is smaller than the diameter of the vertical pipe, the transition pipe is a tapered pipe, and the diameter of the transition pipe increases gradually from bottom to top.

4. The flue denitration ammonia uniform distribution device according to claim 1, characterized in that: Each of the ammonia injection branch pipes is provided with a first regulating valve and a flow meter.

5. The flue denitration ammonia uniform distribution device according to claim 1, characterized in that: The annular distribution pipe is connected to at least two ammonia inlet pipes, and the two ammonia inlet pipes are designed with a symmetrical structure; the cross-sectional area of ​​the annular distribution pipe is greater than twice the sum of the cross-sectional areas of each ammonia injection branch pipe; and a second regulating valve is provided on each ammonia inlet pipe.

6. A denitration ammonia injection system, comprising a flue before denitration, a flue for denitration treatment and a control system, wherein a flue gas inlet is arranged at the first end of the flue before denitration, a flue gas outlet is arranged at the first end of the flue for denitration treatment, and the second end of the flue before denitration and the second end of the flue for denitration treatment are arranged in a sealed communication; a heat exchanger is arranged in communication with the flue before denitration and the flue for denitration treatment; an SCR denitration reactor is arranged between the second end of the flue for denitration treatment and the heat exchanger; characterized in that: At least one flue denitrification ammonia spraying uniform distribution device according to any one of claims 1 to 5 is arranged on the flue before denitrification, between the second end thereof and the heat exchanger, and the flue denitrification ammonia spraying uniform distribution device is arranged perpendicularly to the central axis of the flue before denitrification; a swirl mixing structure is arranged between the flue denitrification ammonia spraying uniform distribution device and the heat exchanger; an ammonia analyzer is arranged between the heat exchanger and the SCR denitrification reactor, and the ammonia analyzer is used to detect the amount of ammonia in the flue gas after denitrification treatment by the SCR denitrification reactor, and the ammonia analyzer is arranged with a plurality of sampling and measuring points, and each of the sampling and measuring points is arranged in one-to-one correspondence with each distributor of the flue denitrification ammonia spraying uniform distribution device.

7. The denitration ammonia injection system according to claim 6, characterized in that: Two flue denitrification ammonia spraying distribution devices are arranged axially parallel and spaced apart on the flue before denitrification, between the second end thereof and the heat exchanger, each of the flue denitrification ammonia spraying distribution devices comprises an annular distribution pipe and at least two independent ammonia spraying structures; each of the ammonia spraying structures comprises an I-shaped branch pipe structure, the I-shaped branch pipe structure comprises a plurality of first-level I-shaped branch pipes, each of the first-level I-shaped branch pipes comprises a first-level central pipe and a first-level transverse branch pipe, and the circumferential angle between the first-level central pipes of the two flue denitrification ammonia spraying distribution devices is the third angle.

8. The denitration ammonia injection system according to claim 7, characterized in that: The third angle ranges from 30° to 60°.

9. The denitration ammonia injection system according to claim 6, characterized in that: The cyclone mixing structure comprises a plurality of cyclone mixers arranged adjacent to each other, the plurality of cyclone mixers are connected to the flue before denitrification via a fixed structure, and the center line connecting three adjacent cyclone mixers forms an equilateral triangle.

10. The denitration ammonia injection system according to claim 9, characterized in that: Each of the swirl mixers comprises an annular frame, a connecting ring is coaxially and radially spaced inside the annular frame, a plurality of inclined first swirl blades are circumferentially spaced between the annular frame and the connecting ring, and the fourth angle between each of the first swirl blades and the central axis of the connecting ring is set equally.

11. The denitration ammonia injection system according to claim 10, characterized in that: The number of the first swirl blades in each of the swirl mixers is 3 to 15, and the range of the fourth angle is 15° to 70°.

12. The denitration and ammonia injection system according to claim 9, characterized in that: Each of the swirl mixers comprises an annular frame, a connecting ring is coaxially and radially spaced inside the annular frame, a center ring is coaxially and radially spaced inside the connecting ring, and a blind plate is arranged at the end of the center ring; a plurality of inclined second swirl blades are circumferentially spaced between the annular frame and the connecting ring, a plurality of inclined third swirl blades are circumferentially spaced between the connecting ring and the center ring, the swirl directions of the third swirl blades and the second swirl blades are oppositely arranged, the fifth angle between each of the second swirl blades and the central axis of the connecting ring is equal, and the sixth angle between each of the third swirl blades and the central axis of the connecting ring is equal.

13. The denitration and ammonia injection system according to claim 12, characterized in that: The number of the second swirl blades in each of the swirl mixers is 6 to 36, and the range of the fifth angle is 25° to 70°; the number of the third swirl blades in each of the swirl mixers is 3 to 24, and the range of the sixth angle is 15° to 65°.

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