A low-nitrogen combustion device with internal flue gas circulation

Abstract

The present invention discloses a low-nitrogen combustion device with internal circulation of flue gas, and relates to the field of clean combustion technology. The low-nitrogen combustion device comprises: a throat, in which flowing combustion-supporting air is arranged; an internal circulation component, which is connected to the throat and arranged behind the throat, and the internal circulation component is provided with a first outlet, a second outlet and an inlet, the first outlet is located behind the throat, the second outlet is opposite to the furnace, and the inlet is located outside the first outlet and the second outlet and opposite to the furnace; the cross-sectional area of ​​the internal circulation component is smaller than the cross-sectional area of ​​the throat, the combustion-supporting air flows through the throat, the first outlet and the second outlet in sequence, the internal circulation flue gas flows through the inlet, the first outlet and the second outlet in sequence, and the combustion-supporting air and the internal circulation flue gas are mixed between the first outlet and the second outlet. The present invention achieves the mixing of the combustion-supporting air and the internal circulation flue gas between the first outlet and the second outlet only by arranging the internal circulation component behind the throat, and making the cross-sectional area of ​​the internal circulation component smaller than the cross-sectional area of ​​the throat.

Description

Technical Field

[0001] The invention relates to the technical field of clean combustion, and in particular to a low-nitrogen combustion device with internal circulation of flue gas. Background Art

[0002] Fuel combustion will inevitably generate nitrogen oxides. There are two main ways to reduce the emission of nitrogen oxides into the atmosphere: low-nitrogen combustion and tail denitrification. Low-nitrogen combustion is to reduce NOx during fuel combustion. X The generation of NO into the atmosphere X concentration; low nitrogen combustion has the characteristics of small initial investment, small scope of transformation and near-zero operating cost. X Already generated, use reducing agent to reduce the NO X , thereby reducing NO emissions into the atmosphere X Concentration, SCR and SNCR are currently used; tail denitrification has large initial investment, high operating costs, and will also produce certain side effects.

[0003] At present, for natural gas fuel, the technical route of low nitrogen burner + flue gas external circulation is adopted, which can reduce NO X The emission is reduced to 30mg / Nm 3 , meeting the most stringent environmental emission standards. Flue gas recirculation technology extracts part of the flue gas (low temperature section) from the flue at the tail end of the boiler and mixes it with the combustion air before sending it into the furnace for combustion. This can reduce the combustion temperature and oxygen content, and can greatly reduce NO X However, as the application time goes by, its shortcomings are gradually found in practice: first, because the low-temperature flue gas participating in the external circulation needs to be led out from the tail of the boiler, it is necessary to add necessary flue gas recirculation components such as flue gas recirculation pipeline, smoke mixing box, and recirculation fan, which leads to a relatively complex structure and high installation cost; second, due to the large temperature difference, condensed water is easily generated, affecting the thermal efficiency.

[0004] Therefore, there is an urgent need for a low-nitrogen combustion device with internal flue gas circulation to solve the above problems. Summary of the invention

[0005] The object of the present invention is to provide a low-nitrogen combustion device with internal circulation of flue gas, so as to solve the problems of complex structure and high application cost of the existing low-nitrogen combustion device.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] A low-nitrogen combustion device with internal flue gas circulation, comprising:

[0008] a throat, in which the combustion air flows;

[0009] an internal circulation component connected to the throat and arranged behind the throat, the internal circulation component being provided with a first outlet, a second outlet and an inlet, the first outlet being located behind the throat, the second outlet being opposite to the furnace, and the inlet being located outside the first outlet and the second outlet and opposite to the furnace;

[0010] The cross-sectional area of ​​the internal circulation component is smaller than the cross-sectional area of ​​the throat, the combustion air flows through the throat, the first outlet and the second outlet in sequence, the internal circulation flue gas flows through the inlet, the first outlet and the second outlet in sequence, and the combustion air and the internal circulation flue gas are mixed between the first outlet and the second outlet.

[0011] Preferably, the opening direction of the first outlet is consistent with the flow direction of the combustion air.

[0012] Preferably, the cross-sectional area of ​​the section formed by the first outlet is smaller than the cross-sectional area of ​​the section formed by the second outlet, and the cross-sectional area of ​​the section formed by the second outlet is smaller than the cross-sectional area of ​​the outlet of the throat.

[0013] Preferably, the device further comprises a flame stabilizer disposed inside the second outlet.

[0014] Preferably, it also includes a gas gun, which can be sequentially installed inside or outside the throat, the internal circulation component and the flame stabilizer.

[0015] Preferably, the cross-sectional area of ​​the flame stabilizer is larger than the cross-sectional area of ​​the cross section formed by the first outlet.

[0016] Preferably, a gas channel for supplying gas is provided in the gas gun, and a gas nozzle is provided at the end, and the gas nozzle is opposite to the furnace.

[0017] Preferably, the internal circulation component includes a first piece and a second piece, the first piece is connected to the throat, a smoke channel for the internal circulating smoke is formed between the second piece and the first piece, and the smoke channel is connected to the inlet and the first outlet respectively.

[0018] Preferably, the cross-sectional diameter of the first member gradually decreases along the flow direction of the combustion air.

[0019] Preferably, the cross-sectional diameter of the flue gas channel gradually decreases along the flow direction of the internal circulating flue gas.

[0020] Beneficial effects of the present invention:

[0021] The present invention only arranges an internal circulation component behind the throat, and makes the cross-sectional area of ​​the internal circulation component smaller than the cross-sectional area of ​​the throat, thereby increasing the air flow rate and dynamic pressure, thereby creating a relatively negative pressure atmosphere at the first outlet. The flue gas in the furnace enters the interior of the internal circulation component along the inlet and the first outlet and mixes with the combustion-supporting air, and then flows out through the second outlet, thereby achieving the mixing of the combustion-supporting air and the internal circulation flue gas between the first outlet and the second outlet, thereby reducing the combustion temperature and oxygen content, and greatly reducing NO X It reduces emissions and solves the problems of complex structure and high application cost of existing low-nitrogen combustion devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which

[0023] Figure 1 It is a structural schematic diagram of a low-nitrogen combustion device with internal circulation of flue gas provided by the present invention;

[0024] Figure 2 yes Figure 1 Schematic diagram of the structure of the inner loop component.

[0025] In the figure:

[0026] 1. Throat; 3. Burner stabilizer;

[0027] 2. Internal circulation component; 21. First outlet; 22. Second outlet; 23. Inlet; 24. First piece; 25. Second piece; 26. Smoke channel;

[0028] 4. Gas gun; 41. Gas channel; 42. Gas nozzle. DETAILED DESCRIPTION

[0029] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0030] like Figure 1 As shown, it is a schematic diagram of the structure of the low-nitrogen combustion device with internal flue gas circulation provided by the present invention, the low-nitrogen combustion device comprises a throat 1 and an internal circulation component 2 located behind the throat 1, and flowing combustion-supporting air is arranged in the throat 1, and the combustion-supporting air flows out of the throat 1 and then flows into the internal circulation component 2. Figure 2 As shown, the internal circulation component 2 includes a first piece 24 and a second piece 25, and a smoke channel 26 for the flow of internal circulating smoke is formed between the first piece 24 and the second piece 25. The outer side of the smoke channel 26 is provided with an inlet 23 connected to the furnace, and the inner side is provided with a first outlet 21 and a second outlet 22. The first outlet 21 is located behind the throat 1, and the second outlet 22 is opposite to the furnace. The inlet 23, the smoke channel 26, the first outlet 21 and the second outlet 22 are connected in sequence.

[0031] The cross-sectional area of ​​the internal circulation component 2 is smaller than that of the throat 1. The combustion air flows through the throat 1, the first outlet 21 and the second outlet 22 in sequence, and the internal circulation flue gas flows through the inlet 23, the first outlet 21 and the second outlet 22 in sequence. The combustion air and the internal circulation flue gas are mixed between the first outlet 21 and the second outlet 22. The present invention only arranges the internal circulation component 2 behind the throat 1, and makes the cross-sectional area of ​​the internal circulation component 2 smaller than that of the throat 1, thereby increasing the air flow rate and creating a relatively negative pressure atmosphere at the first outlet 21. The flue gas in the furnace enters the interior of the internal circulation component 2 along the inlet 23 and the first outlet 21 and mixes with the combustion air, and then flows out through the second outlet 22, thereby achieving the mixing of the combustion air and the internal circulation flue gas between the first outlet 21 and the second outlet 22. This can reduce the combustion temperature and oxygen content, and can greatly reduce NO X It reduces emissions and solves the problems of complex structure and high application cost of existing low-nitrogen combustion devices.

[0032] Specifically, the opening direction of the first outlet 21 is consistent with the flow direction of the combustion air, so that the internal circulating flue gas flowing out of the first outlet 21 can be prevented from mixing with the combustion air in a non-parallel manner, thereby increasing the forward resistance of the combustion air.

[0033] Specifically, the cross-sectional area of ​​the section formed by the first outlet 21 is smaller than the cross-sectional area of ​​the section formed by the second outlet 22, and the cross-sectional area of ​​the section formed by the second outlet 22 is smaller than the cross-sectional area of ​​the outlet of the throat 1. In this way, the flow rate of the combustion-supporting air and the internally circulating flue gas at the first outlet 21 is the largest, and then the flow rate is reduced, so that the two are mixed more fully, and finally the fully mixed low-oxygen air is discharged from the second outlet 22.

[0034] Specifically, a flame stabilizer 3 is provided inside the second outlet 22. After the mixed gas from the first outlet 21 passes through the flame stabilizer 3, the gas injected into the furnace can be more stable, which can further reduce NO X The flame stabilizer 3 plays a role in stabilizing flame and combustion, and its type can be a swirler or a flat plate, and the present invention does not limit its type.

[0035] Specifically, the low nitrogen combustion device further includes a gas gun 4, which can be sequentially arranged inside or outside the throat 1, the internal circulation component 2 and the flame stabilizer 3. Figure 1 Only the situation that the gas gun 4 is arranged outside is shown. A gas channel 41 for supplying gas is arranged inside the gas gun 4, and a gas nozzle 42 is arranged at the end, and the gas nozzle 42 is opposite to the furnace.

[0036] Specifically, the cross-sectional area of ​​the flame stabilizer 3 is larger than the cross-sectional area of ​​the cross section formed by the first outlet 21 , so that the mixed air flowing out of the first outlet 21 can mainly flow out to the space between the flame stabilizer 3 and the second outlet 22 .

[0037] Specifically, the internal circulation component 2 includes a first piece 24 and a second piece 25, the first piece 24 is connected to the throat 1, and a smoke channel 26 for internal circulating flue gas is formed between the second piece 25 and the first piece 24, and the smoke channel 26 is connected to the inlet 23 and the first outlet 21 respectively. The cross-sectional diameter of the first piece 24 along the flow direction of the combustion air gradually decreases, and the cross-sectional diameter of the smoke channel 26 along the flow direction of the internal circulating flue gas gradually decreases, so that the flow rate of the combustion air and the internal circulating flue gas can be increased, that is, the flow rate at the first outlet 21 reaches the maximum, so that the mixing degree of the two is the best. It can be understood that the smoke channel 26 can also be gradually expanded (that is, the cross-sectional diameter along the flow direction of the internal circulating flue gas gradually increases). The present invention does not limit the cross-sectional diameter of the smoke channel 26, but it is preferably that the cross-sectional diameter gradually decreases.

[0038] The working process of the above-mentioned low-nitrogen combustion device with internal flue gas circulation is as follows:

[0039] The fuel required for combustion is sprayed into the furnace through the gas nozzle 42 from the gas channel 41 of the gas gun 4, and the combustion air required for combustion is sprayed into the furnace through the throat 1 and the internal circulation component 2. When the combustion air flows through the internal circulation component 2, the flow area of ​​the combustion air gradually decreases, and the flow rate of the combustion air gradually increases, that is, the dynamic pressure increases and the static pressure decreases. When it flows to the first outlet 21, the flow rate of the combustion air increases to the maximum. The first outlet 21 is at a negative pressure relative to the inlet 23. The high-flow rate combustion air sucks in the external high-temperature flue gas. The high-temperature flue gas passes through the inlet 23 of the internal circulation component 2, the flue gas channel 26 and the first outlet 21, and then mixes with the combustion air flowing out of the throat 1 to form a low-oxygen air-to-gas mixture. After passing through the stabilizer 3, it encounters the gas sprayed into the furnace from the gas gun 4, and performs low-oxygen combustion, which reduces the probability of oxygen and nitrogen combining during fuel combustion, thereby reducing thermal NO X It also reduces the chance of oxygen and fuel compounds combining, thereby reducing fuel NO X The generation of NO after fuel combustion is greatly reduced X At the same time, because the device can realize internal circulation of flue gas, it can reduce the use of external flue gas recirculation and reduce the adverse effects of external flue gas recirculation.

[0040] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A low-nitrogen combustion device with internal flue gas circulation, characterized in that: include: a throat (1) in which combustion air flows; an internal circulation component (2), which is connected to the throat (1) and is arranged behind the throat (1); the internal circulation component (2) is provided with a first outlet (21), a second outlet (22) and an inlet (23); the first outlet (21) is located behind the throat (1); the second outlet (22) is opposite to the furnace; and the inlet (23) is located outside the first outlet (21) and the second outlet (22) and opposite to the furnace; The cross-sectional area of ​​the internal circulation component (2) is smaller than the cross-sectional area of ​​the throat (1); the combustion-supporting air flows through the throat (1), the first outlet (21) and the second outlet (22) in sequence; the internal circulation flue gas flows through the inlet (23), the first outlet (21) and the second outlet (22) in sequence; the combustion-supporting air and the internal circulation flue gas are mixed between the first outlet (21) and the second outlet (22); The opening direction of the first outlet (21) is consistent with the flow direction of the combustion air; The cross-sectional area of ​​the section formed by the first outlet (21) is smaller than the cross-sectional area of ​​the section formed by the second outlet (22), and the cross-sectional area of ​​the section formed by the second outlet (22) is smaller than the cross-sectional area of ​​the outlet of the throat (1); It also includes a flame stabilizer (3) disposed inside the second outlet (22); It also comprises a gas gun (4), which can be sequentially installed inside or outside the throat (1), the internal circulation component (2) and the flame stabilizer (3).

2. The low-nitrogen combustion device with internal flue gas circulation according to claim 1, characterized in that: The cross-sectional area of ​​the flame stabilizer (3) is greater than the cross-sectional area of ​​the section formed by the first outlet (21).

3. The low-nitrogen combustion device with internal flue gas circulation according to claim 1 is characterized in that: The gas gun (4) is provided with a gas channel (41) for supplying gas, and a gas nozzle (42) is provided at the end thereof, and the gas nozzle (42) is opposite to the furnace.

4. The low-nitrogen combustion device with internal flue gas circulation according to claim 1, characterized in that: The internal circulation component (2) comprises a first piece (24) and a second piece (25), wherein the first piece (24) is connected to the throat (1), and a smoke channel (26) for the internal circulating smoke is formed between the second piece (25) and the first piece (24), and the smoke channel (26) is respectively connected to the inlet (23) and the first outlet (21).

5. The low-nitrogen combustion device with internal flue gas circulation according to claim 4 is characterized in that: The cross-sectional diameter of the first member (24) gradually decreases along the flow direction of the combustion-supporting air.

6. The low-nitrogen combustion device with internal flue gas circulation according to claim 4 is characterized in that: The cross-sectional diameter of the smoke channel (26) gradually decreases along the flow direction of the internal circulating smoke.

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