Low-nitrogen combustion structure for flue gas internal circulation
By adopting a low-nitrogen combustion structure with internal flue gas circulation in the gas boiler, and using the venturi pipe to sweep smoke to dilute the gas fuel, the problem of thermal NOx emissions in natural gas combustion is solved, and the effective control of NOx emissions is achieved.
Patent Information
- Application Number
- CN202421757168.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-23
- Publication Date
- 2025-05-02
- Estimated Expiration
- 2034-07-23
AI Technical Summary
During the combustion of natural gas, how to effectively control the emission of thermal NOx to prevent environmental problems such as acid rain.
Using a low-nitrogen combustion structure with internal flue gas circulation, a central gas fuel nozzle, a central air inlet duct and a gas fuel pipe are inserted on the furnace wall, and a venturi pipe is installed on the gas fuel pipe. There are through holes on the venturi pipe to roll the smoke gas, dilute the gas fuel concentration, and reduce the flame temperature, thereby controlling the formation of thermal nitrogen oxides.
The graded combustion of gas fuel is achieved, the uniformity of the main flame is increased, the concentration of gas fuel is diluted, the flame temperature is reduced, the generation of thermal NOx is effectively controlled, and the NOx emission is reduced.
Smart Images
Figure CN222824359U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to a low-nitrogen combustion structure, in particular to a low-nitrogen combustion structure with internal circulation of flue gas, belonging to the technical field of boiler combustion devices. Background Art
[0002] Under the background goal of "dual carbon", my country attaches more importance to the development and exploration of renewable energy. At present, natural gas has been widely used due to its advantages of high safety, high calorific value and low price. Hydrogen (H2) is a common carbon-free energy with low minimum ignition energy, wide flammable range, good economy and safety under lean combustion conditions. It has received more and more attention in recent years, so it is expected to become an alternative energy source to fossil energy. Natural gas blending with hydrogen can comprehensively utilize the advantages of natural gas and hydrogen, optimize the combustion characteristics of fuel, and is an effective solution to achieve the "dual carbon" goal in the gas field.
[0003] Although the combustion of gas fuel generates fewer pollutants than pulverized coal, it still produces thermal NOx due to its high flame temperature. Excessive NOx emissions can lead to environmental phenomena such as acid rain. Therefore, with the large-scale use of natural gas resources, how to reasonably control NOx emissions has become a problem worthy of attention. Utility Model Content
[0004] The utility model aims at the above-mentioned deficiencies of the prior art and further provides a low-nitrogen combustion structure with internal circulation of flue gas.
[0005] The technical solution of the utility model is: a low-nitrogen combustion structure with internal circulation of flue gas, comprising a central gas fuel nozzle, a central air inlet pipe and a plurality of gas fuel pipes.
[0006] The central gas fuel nozzle, the central air inlet pipe and the gas fuel pipe are all inserted into the furnace wall. The central air inlet pipe is coaxially sleeved on the central gas fuel nozzle. A plurality of gas fuel pipes are arranged around the central air inlet pipe in a circular array, and the axis of the gas fuel pipe is parallel to the axis of the central air inlet pipe. A Venturi tube is installed on the gas fuel pipe. The Venturi tube includes a feed pipe, a throat pipe and a discharge pipe which are coaxially fixed in sequence, and the feed pipe is coaxially fixed to the gas fuel pipe.
[0007] The venturi tube is provided with a plurality of through holes for entraining smoke in a circular array. The distance between the outer surface of the venturi tube and the outer surface of the central air inlet pipe is L. The outer diameter of the venturi tube outlet is B, and L≤B.
[0008] Compared with the prior art, the utility model has the following effects:
[0009] 1. The gas fuel pipes 300 of the present invention are arranged in a circular array around the central air inlet pipe 200, which can not only realize the staged combustion of the gas fuel, but also increase the uniformity of the main flame (ie, the flame formed by the central gas fuel nozzle 100).
[0010] 2. The gas fuel in the gas fuel pipe 300 has an increased flow rate after flowing out of the venturi tube 400, and the high-temperature flue gas in the furnace is sucked into the venturi tube 400 through the through hole 410, thereby diluting the gas fuel concentration and reducing the flame temperature to achieve control of the generation of thermal nitrogen oxides.
[0011] 3. The utility model has a simple structure and has the function of reducing NOx emissions. It can be applied to various occasions using gas fuels, such as gas boilers, oil field gas injection furnaces, industrial kilns, etc. Today, when the country vigorously advocates clean and environmental protection, it has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Figure 1 It is a structural schematic diagram of the utility model;
[0013] Figure 2 It is the front view of the utility model;
[0014] Figure 3 It is a first schematic diagram of the venturi tube 400 of the present invention;
[0015] Figure 4 is a second schematic diagram of the venturi tube 400 of the present invention;
[0016] Figure 5 It is a third schematic diagram of the venturi tube 400 of the present invention.
[0017] In the figure: 100, central gas fuel nozzle; 200, central air inlet pipe; 300, gas fuel pipe; 400, venturi tube; 410, through hole; 420, feed pipe; 430, throat; 440, discharge pipe. DETAILED DESCRIPTION
[0018] In order to make the purpose, features and advantages of the present invention more obvious and understandable, the technical solution in this embodiment will be clearly and completely described below in conjunction with the accompanying drawings of the present invention.
[0019] Specific implementation method 1: Combination Figure 1 and Figure 2 The present embodiment is described. A low-nitrogen combustion structure with internal flue gas circulation in the present embodiment includes a central gas fuel nozzle 100 , a central air inlet pipe 200 and a plurality of gas fuel pipes 300 .
[0020] The central gas fuel nozzle 100, the central air inlet pipe 200 and the gas fuel pipe 300 are all inserted on the furnace wall. The central air inlet pipe 200 is coaxially sleeved on the central gas fuel nozzle 100. A plurality of gas fuel pipes 300 are arranged around the central air inlet pipe 200 in a circular array, and the axis of the gas fuel pipe 300 is parallel to the axis of the central air inlet pipe 200. A venturi tube 400 is installed on the gas fuel pipe 300. The venturi tube 400 includes a feed pipe 420, a throat pipe 430 and a discharge pipe 440 which are coaxially fixed in sequence. The feed pipe 420 is coaxially fixed to the gas fuel pipe 300.
[0021] The venturi tube 400 is provided with a plurality of through holes 410 for entraining the smoke in a circular array. With such arrangement, the gas fuel in the gas fuel pipe 300 increases its flow rate after flowing out of the venturi tube 400, and the high-temperature smoke in the furnace is entrained into the venturi tube 400 through the through holes 410, and then mixed with the gas fuel and sprayed into the furnace, thereby diluting the gas fuel concentration and reducing the flame temperature, so as to control the generation of thermal nitrogen oxides. The distance between the outer surface of the venturi tube 400 and the outer surface of the central air inlet pipe 200 is L, and the outer diameter at the outlet of the venturi tube 400 is B, and L≤B.
[0022] In this embodiment, the number of the gas fuel pipes 300 is 3 to 16.
[0023] In this embodiment, the materials of the central gas fuel nozzle 100, the central air inlet pipe 200, the gas fuel pipe 300 and the venturi tube 400 are all stainless steel, preferably 316 stainless steel.
[0024] The following is a further description of the specific embodiments of the present invention with reference to the accompanying drawings:
[0025] Example 1: Figure 2 and Figure 3 As shown, the central gas fuel nozzle 100, the central air inlet pipe 200 and the gas fuel pipe 300 are all inserted on the furnace wall, the central air inlet pipe 200 is coaxially sleeved on the central gas fuel nozzle 100, and a plurality of gas fuel pipes 300 are arranged around the central air inlet pipe 200 in a circular array, and the axis of the gas fuel pipe 300 is parallel to the axis of the central air inlet pipe 200. A venturi tube 400 is installed on the gas fuel pipe 300, and the venturi tube 400 includes a feed pipe 420, a throat pipe 430 and a discharge pipe 440 which are coaxially fixed in sequence.
[0026] The longitudinal section of the throat pipe 430 is in a hyperbolic shape, and the feed pipe 420 and the discharge pipe 440 are both hollow cylindrical tubes.
[0027] The throat pipe 430 is provided with 10 rectangular through holes 410 in a circular array, and the opening rate of the throat pipe 430 is 30% to 70%; the feed pipe 420 is provided with 4 rectangular through holes 410 in a circular array, and the opening rate of the feed pipe 420 is not less than 50%.
[0028] The inner diameters of the feed pipe 420 and the discharge pipe 440 are both D 400 , the inner diameter of the gas fuel pipe 300 is D 300 , and D 400 =2~3·D 300 The end surface of the feed pipe 420 is connected to the outer circumferential surface of the gas fuel pipe 300 through a flange.
[0029] The inner diameter of the throat 430 at its thinnest point is D 430 The outlet of the gas fuel pipe 300 is integrally provided with a tapered pipe with a gradually decreasing diameter. The inner diameter of the large end of the tapered pipe is D1, and the inner diameter of the small end of the tapered pipe is D2, and D1 = 1.5 ~ 3 · D2, D 430 =1.5~2.5·D2.
[0030] The distance between the outer surface of the discharge pipe 440 and the outer surface of the central air inlet pipe 200 is L, the outer diameter of the discharge pipe 440 is B, and L≤B.
[0031] Example 2: Figure 2 and Figure 4 As shown, the central gas fuel nozzle 100, the central air inlet pipe 200 and the gas fuel pipe 300 are all inserted on the furnace wall, the central air inlet pipe 200 is coaxially sleeved on the central gas fuel nozzle 100, and a plurality of gas fuel pipes 300 are arranged around the central air inlet pipe 200 in a circular array, and the axis of the gas fuel pipe 300 is parallel to the axis of the central air inlet pipe 200. A venturi tube 400 is installed on the gas fuel pipe 300, and the venturi tube 400 includes a feed pipe 420, a throat pipe 430 and a discharge pipe 440 which are coaxially fixed in sequence.
[0032] The longitudinal section of the throat pipe 430 is in a hyperbolic shape, and the feed pipe 420 and the discharge pipe 440 are both hollow cylindrical tubes.
[0033] Ten rectangular through holes 410 are formed in a circular array on the throat pipe 430 , and the opening rate of the throat pipe 430 is 30% to 70%.
[0034] The inner diameters of the feed pipe 420 and the discharge pipe 440 are both D 400 , the inner diameter of the gas fuel pipe 300 is D 300 , and D 400 =2~3·D 300 The inner circumferential surface of the feed pipe 420 is connected to the outer circumferential surface of the gas fuel pipe 300 through ribs.
[0035] The inner diameter of the throat 430 at its thinnest point is D 430 The outlet of the gas fuel pipe 300 is integrally provided with a tapered pipe with a gradually decreasing diameter. The inner diameter of the large end of the tapered pipe is D1, and the inner diameter of the small end of the tapered pipe is D2, and D1 = 1.5 ~ 3 · D2, D 430 =1.5~2.5·D2.
[0036] The distance between the outer surface of the discharge pipe 440 and the outer surface of the central air inlet pipe 200 is L, the outer diameter of the discharge pipe 440 is B, and L≤B.
[0037] Example 3: Figure 2 and Figure 5 As shown, the central gas fuel nozzle 100, the central air inlet pipe 200 and the gas fuel pipe 300 are all inserted on the furnace wall, the central air inlet pipe 200 is coaxially sleeved on the central gas fuel nozzle 100, and a plurality of gas fuel pipes 300 are arranged around the central air inlet pipe 200 in a circular array, and the axis of the gas fuel pipe 300 is parallel to the axis of the central air inlet pipe 200. A venturi tube 400 is installed on the gas fuel pipe 300, and the venturi tube 400 includes a feed pipe 420, a throat pipe 430 and a discharge pipe 440 which are coaxially fixed in sequence.
[0038] The throat pipe 430 is a hollow cylindrical pipe, and the feed pipe 420 and the discharge pipe 440 are both trumpet-shaped pipes.
[0039] The discharge pipe 440 is provided with eight rectangular through holes 410 in a circular array, and the opening rate of the discharge pipe 440 is 30% to 70%.
[0040] The inner diameter of the gas fuel pipe 300 is D 300 , the inner diameter of the large end of the discharge pipe 440 is D 441 , and D 441 =2~4·D 300 .
[0041] The inner diameter of the large end of the feed pipe 420 is D 421 The inner diameter of the small end of the feed pipe 420 is D 422 , and D 421 =1.5~3·D 422 The large end surface of the feed pipe 420 is fixedly connected to the end surface of the gas fuel pipe 300. This arrangement facilitates the connection between the venturi tube 400 and the gas fuel pipe 300.
[0042] The distance between the maximum outer diameter of the discharge pipe 440 and the outer surface of the central air inlet pipe 200 is L, the outer diameter of the large end of the discharge pipe 440 is B, and L≤B.
[0043] How it works
[0044] The central gas fuel nozzle 100, the central air inlet pipe 200 and the gas fuel pipe 300 are all inserted into the furnace wall. The central air inlet pipe 200 is coaxially sleeved on the central gas fuel nozzle 100. Several gas fuel pipes 300 are arranged around the central air inlet pipe 200 in a circular array. The main flame formed by the central gas fuel nozzle 100 burns stably at the outlet of the central gas fuel nozzle 100.
[0045] A venturi tube 400 is installed on the gas fuel pipe 300, and a through hole 410 is opened on the venturi tube 400. The flow velocity of the gas fuel in the gas fuel pipe 300 is increased after flowing out of the venturi tube 400, and the high-temperature flue gas in the furnace is sucked into the venturi tube 400 through the through hole 410, and then mixed with the gas fuel and continued to be sprayed into the furnace, thereby diluting the gas fuel concentration and reducing the flame temperature, so as to control the generation of thermal nitrogen oxides.
[0046] The present invention has been disclosed as above in the form of a preferred embodiment, but it is not intended to limit the present invention. Any simple modification, equivalent changes and modifications made to the above implementation cases by any professional and technical personnel who do not deviate from the content of the technical solution of the present invention and based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.
Claims
1. A low-nitrogen combustion structure with internal flue gas circulation, characterized in that: It comprises a central gas fuel nozzle (100), a central air inlet pipe (200) and a plurality of gas fuel pipes (300); The central gas fuel nozzle (100), the central air inlet pipe (200) and the gas fuel pipe (300) are all inserted on the furnace wall; the central air inlet pipe (200) is coaxially sleeved on the central gas fuel nozzle (100); a plurality of gas fuel pipes (300) are arranged around the central air inlet pipe (200) in a circular array, and the axis of the gas fuel pipe (300) is parallel to the axis of the central air inlet pipe (200); a venturi tube (400) is installed on the gas fuel pipe (300); the venturi tube (400) comprises a feed pipe (420), a throat pipe (430) and a discharge pipe (440) which are coaxially fixed in sequence; the feed pipe (420) is coaxially fixed to the gas fuel pipe (300); The venturi tube (400) is provided with a plurality of through holes (410) for entraining smoke in a circular array, the distance between the outer surface of the venturi tube (400) and the outer surface of the central air inlet pipe (200) is L, the outer diameter of the venturi tube (400) at the outlet is B, and L≤B.
2. A low-nitrogen combustion structure with internal flue gas circulation according to claim 1, characterized in that: The longitudinal section of the throat pipe (430) is a hyperbola, and the feed pipe (420) and the discharge pipe (440) are both hollow cylindrical tubes; A plurality of through holes (410) are formed on the throat pipe (430) and the feed pipe (420) in a circumferential array, the opening rate of the throat pipe (430) is 30% to 70%, and the opening rate of the feed pipe (420) is not less than 50%; The inner diameters of the feed pipe (420) and the discharge pipe (440) are both D 400 The inner diameter of the gas fuel pipe (300) is D 300 , and D 400 =(2~3)·D 300 , the end surface of the feed pipe (420) is connected to the outer circumferential surface of the gas fuel pipe (300) via a flange; The inner diameter of the throat (430) at its narrowest point is D 430 The outlet of the gas fuel pipe (300) is integrally provided with a tapered pipe with a gradually decreasing diameter, the inner diameter of the large end of the tapered pipe is D1, the inner diameter of the small end of the tapered pipe is D2, and D1 = (1.5-3)·D2, D 430 =(1.5~2.5)·D2; The distance between the outer surface of the discharge pipe (440) and the outer surface of the central air inlet pipe (200) is L, the outer diameter of the discharge pipe (440) is B, and L≤B.
3. The low-nitrogen combustion structure with internal flue gas circulation according to claim 1 is characterized in that: The longitudinal section of the throat pipe (430) is a hyperbola, and the feed pipe (420) and the discharge pipe (440) are both hollow cylindrical tubes; A plurality of through holes (410) are formed on the throat (430) in a circumferential array, and the opening rate of the throat (430) is 30% to 70%. The inner diameters of the feed pipe (420) and the discharge pipe (440) are both D 400 The inner diameter of the gas fuel pipe (300) is D 300 , and D 400 =(2~3)·D 300 , the inner circumferential surface of the feed pipe (420) and the outer circumferential surface of the gas fuel pipe (300) are connected via ribs; The inner diameter of the throat (430) at its narrowest point is D 430 The outlet of the gas fuel pipe (300) is integrally provided with a tapered pipe with a gradually decreasing diameter, the inner diameter of the large end of the tapered pipe is D1, the inner diameter of the small end of the tapered pipe is D2, and D1 = (1.5-3)·D2, D 430 =(1.5~2.5)·D2; The distance between the outer surface of the discharge pipe (440) and the outer surface of the central air inlet pipe (200) is L, the outer diameter of the discharge pipe (440) is B, and L≤B.
4. The low-nitrogen combustion structure with internal flue gas circulation according to claim 1 is characterized in that: The throat pipe (430) is a hollow cylindrical pipe, and the feed pipe (420) and the discharge pipe (440) are both trumpet-shaped pipes; A plurality of through holes (410) are formed on the discharge pipe (440) in a circular array, and the opening rate of the discharge pipe (440) is 30% to 70%. The inner diameter of the gas fuel pipe (300) is D 300 The inner diameter of the large end of the discharge pipe (440) is D 441 , and D 441 =(2~4)·D 300 ; The inner diameter of the large end of the feed pipe (420) is D 421 The inner diameter of the small end of the feed pipe (420) is D 422 , and D 421 =(1.5~3)·D 422 , the large end surface of the feed pipe (420) is fixedly connected to the end surface of the gas fuel pipe (300); The distance between the maximum outer diameter of the discharge pipe (440) and the outer surface of the central air inlet pipe (200) is L, the outer diameter of the large end of the discharge pipe (440) is B, and L≤B.
5. The low-nitrogen combustion structure with internal flue gas circulation according to claim 1 is characterized in that: The number of the gas fuel pipes (300) is 3 to 16.
6. A low-nitrogen combustion structure with internal flue gas circulation according to claim 5, characterized in that: The central gas fuel nozzle (100), the central air inlet pipe (200), the gas fuel pipe (300) and the venturi tube (400) are all made of stainless steel.