A flue gas internal circulation type low-nitrogen combustion device

Abstract

The present invention relates to a low-nitrogen combustion device with flue gas internal circulation, which includes a burner throat with a flue gas internal reflux suction inlet provided on the cavity wall, and a gas channel, a combustion-supporting air channel and a jet-induced flue gas internal circulation device arranged inside the cavity. The jet-induced flue gas internal circulation device comprises an L-shaped flue gas pipe formed by the intersection and interconnection of a horizontal flue gas inlet pipe and a longitudinal flue gas outlet pipe, and a Venturi-type tapered combustion-supporting air pipe formed by the interconnection of a tapered pipe and a straight pipe inserted and fixed on the cavity wall at the intersection of the L-shaped flue gas pipe. Most of the combustion-supporting air accelerates and generates negative pressure when flowing through the periphery of each jet-induced flue gas internal circulation device, and a small part accelerates when flowing through the Venturi-type tapered combustion-supporting air pipe and generates negative pressure in the longitudinal flue gas outlet pipe. Under the dual negative pressure action, the flue gas outside the throat is sucked and rolled back into the longitudinal flue gas outlet pipe by the horizontal flue gas inlet pipe to be mixed, and is mixed into the combustion-supporting air channel under the action of the surrounding negative pressure to form an oxygen-deficient combustion-supporting gas, which is then injected into the furnace to participate in low-nitrogen combustion.

Description

Technical Field

[0001] The present invention relates to the technical field of boiler combustion devices, and in particular to a jet-suction type flue gas internal recirculation low-nitrogen combustion device that has the function of sucking and guiding the flue gas in the outer area of the burner throat into the throat, mixing it with combustion-supporting air, and then injecting it into the furnace to participate in low-nitrogen combustion, which helps to reduce the generation amount of NOx. Background Art

[0002] Nitrogen oxides (NOx) contained in the exhaust gas discharged from boilers fueled by fossil resources such as natural gas, coal, and petroleum are recognized air pollutants. For this reason, functional departments have formulated increasingly stringent exhaust gas emission standards for strict control. Now, a standard requirement that the NOx emission must be reduced to 30 mg / Nm 3 has been introduced. In response to this, the industry generally adopts the method of equipping existing boilers with low-nitrogen combustion technology devices for low-nitrogen compliance transformation, and has found the theoretical basis that appropriately reducing the flame temperature during fuel combustion and the oxygen content of the combustion gas helps to reduce the generation amount of NOx. For gas boilers fueled by high-calorific value gases such as natural gas, the current low-nitrogen route of low-nitrogen burner + flue gas external circulation technology is adopted. The flue gas external circulation technology therein is realized by guiding a part of the flue gas to be discharged with relatively low temperature and oxygen content from the boiler tail back into the furnace to participate in mixed combustion. However, it is found in practice that when the boiler adopts the flue gas external circulation technology, it is necessary to add external circulation components including a flue gas circulation fan and a flue gas circulation pipeline to the boiler in order to guide and transport a part of the flue gas to be discharged to specific positions of the burner and related boiler components. The setting is relatively troublesome and the transformation cost is also relatively high. In addition, due to the temperature difference between the mixed gases, condensate will be generated during mixing. In addition to the extra energy consumption required for water evaporation, it will also cause corrosion of the surrounding components, and there are also disadvantages of a large amount of daily maintenance work and relatively high daily use cost. Therefore, from the perspectives of practicability and economy, it is not ideal. Summary of the Invention

[0003] The purpose of the present invention is to overcome the deficiencies existing in the existing low-nitrogen combustion technology, and provide a jet-suction type flue gas internal recirculation low-nitrogen combustion device that has the function of sucking and refluxing the peripheral flue gas near the throat into the throat cavity, mixing it with combustion-supporting air, and then injecting it into the furnace to participate in low-nitrogen combustion, which helps to reduce the generation amount of NOx.

[0004] A flue gas internal circulation type low-nitrogen combustion device of the present invention mainly includes a burner throat, a gas channel composed of a gas pipe connected to the intake end of a gas spray gun, and a combustion-supporting air channel composed of a burner throat annular cavity located outside the gas pipe. Its characteristics are that it further includes a flue gas internal recirculation suction port arranged on the wall of the burner throat cavity and a jet-suction type flue gas internal circulation device arranged in the burner throat cavity, wherein:

[0005] The burner throat body is cylindrical, and a gas passage served by the gas pipe is fixedly arranged at its axial position, and a plurality of flue gas internal reflow inlets are arranged as required on the cavity wall near the tail end on the side close to the furnace wall;

[0006] The jet-suction type flue gas internal circulation device is fixedly arranged on the inner side wall of the burner throat corresponding to the setting position of the flue gas internal reflux suction port, and includes an L-shaped flue gas pipe whose main body is formed by the intersection and interconnection of a horizontal flue gas inlet pipe and a longitudinal flue gas outlet pipe, and a Venturi-type gradually contracting combustion-supporting air duct which is formed by the coaxial interconnection of a gradually contracting pipe and a straight-through pipe inserted and fixedly arranged on the cavity wall at the L-shaped intersection and interconnection of the horizontal flue gas inlet pipe and the longitudinal flue gas outlet pipe;

[0007] In addition, the jet-suction type flue gas internal circulation device is connected to the edge of the flue gas internal reflux suction port by fixed welding through the end of the horizontal flue gas inlet pipe and is fixedly arranged in the combustion-supporting air channel at the burner throat.

[0008] During operation, the gas is delivered from the gas pipe to supply gas to each gas spray gun; the combustion-supporting air enters from the tail end of the throat and flows forward in the combustion-supporting air channel, most of which flows forward around the periphery of the ejection-suction type flue gas internal circulation device, and is continuously accelerated due to the reduction of the flow area when flowing through each ejection-suction type flue gas internal circulation device, and a negative pressure is generated on the periphery of the longitudinal flue gas outlet pipe, which can suck the mixed gas in the pipe out into the combustion-supporting air channel; a small part is aligned with the port of the reducer of the Venturi-type reducer combustion-supporting air duct, flows in along the trend, is accelerated by the reducer to become a high-speed airflow, and then flows out through the straight-through pipe, The smoke enters the longitudinal flue gas outlet pipe, and negative pressure is generated in the longitudinal flue gas outlet pipe, which can suck the gas in the horizontal flue gas inlet pipe into the longitudinal flue gas outlet pipe. As a result, under the action of double negative pressure, the smoke at the periphery of the throat is sucked back into the longitudinal flue gas outlet pipe through the horizontal flue gas inlet pipe, and after being mixed with the high-speed combustion-supporting air from the straight-through pipe, it enters the combustion-supporting air channel under the suction of the negative pressure around the longitudinal flue gas outlet pipe, and merges with the majority of the continuously accelerating combustion-supporting air to form a mixed flue gas flow with a certain flow rate and a certain reduced oxygen content, which is sprayed forward into the furnace to participate in low-nitrogen combustion that helps to suppress and reduce the generation of NOx.

[0009] Based on the above concept, the jet - induced flue - gas internal - recirculation low - nitrogen combustion device of the present invention is provided with a number of flue - gas internal - recirculation suction inlets on the wall of the burner throat cavity as required. Inside the burner throat cavity, a number of jet - induced flue - gas internal - circulation devices are fixedly installed, which are correspondingly connected to the flue - gas internal - recirculation suction inlets and have the function of sucking in the flue gas around the throat and mixing it with the combustion - supporting air. During operation, it can suck the flue gas around the throat into the throat cavity and mix it with the combustion - supporting air moving forward at high speed, effectively reducing the oxygen content in the combustion - supporting gas, thereby ensuring low - nitrogen combustion with effectively suppressed NOx generation and providing technical support for the compliance transformation of boilers. The technical solution of the present invention is simple, scientific and reasonable, safe and reliable in operation, and has a high degree of automation. It can achieve the substantial effect of reducing NOx emissions through flue - gas internal - circulation, filling the industry gap and having strong practicability and broad market application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is the basic structural schematic diagram of an embodiment of the present invention;

[0011] Figure 2 is Figure 1 the view in the direction of A of

[0012] Figure 3 is the structural schematic diagram of the jet - induced flue - gas internal - circulation device in an embodiment of the present invention;

[0013] Figure 4 is Figure 3 the view in the direction of A of

[0014] Figure 5 is the working schematic diagram of an embodiment of the present invention.

[0015] In the figure:

[0016] 1. Burner throat; 2. Gas channel; 21. Gas pipe; 3. Combustion - supporting air channel

[0017] 4. Flue - gas internal - recirculation suction inlet; 5. Jet - induced flue - gas internal - circulation device; 51. L - shaped flue - gas pipe

[0018] 511. Horizontal flue - gas inlet pipe; 512. Vertical flue - gas outlet pipe

[0019] 52. Venturi - type tapered combustion - supporting air pipe; 521. Tapered pipe; 522. Straight - through pipe; 6. Furnace wall DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] The present invention will be further described below with reference to the drawings and typical embodiments.

[0021] In Figures 1 to 5In a low-nitrogen combustion device with flue gas internal circulation of the present invention, the main body includes a burner throat 1, a gas channel 2 formed by a gas pipe 21 connected to the intake end of a gas spray gun, and a combustion-supporting air channel 3 formed by a burner throat annular cavity located outside the gas pipe 21. It is characterized in that it further includes a flue gas internal reflux suction port 4 provided on the cavity wall of the burner throat 1 and a jet-suction type flue gas internal circulation device 5 provided in the cavity of the burner throat 1, where:

[0022] The main body of the burner throat 1 is cylindrical, and a gas channel 2 formed by the gas pipe 21 is fixedly provided at its axial center position. A plurality of the flue gas internal reflux suction ports 4 are provided as required on the cavity wall near the tail end on the side close to the furnace wall 6.

[0023] The jet-suction type flue gas internal circulation device 5 is fixedly provided on the inner side wall of the burner throat 1 corresponding to the setting position of the flue gas internal reflux suction port 4, and includes an L-shaped smoke pipe 51 whose main body is formed by the intersection and interconnection of a horizontal flue gas inlet pipe 511 and a longitudinal flue gas outlet pipe 512, and a Venturi type tapered combustion-supporting air pipe 52 formed by the coaxial interconnection of a tapered pipe 521 and a straight pipe 522 inserted and fixed on the cavity wall at the L-shaped intersection and interconnection of the horizontal flue gas inlet pipe 511 and the longitudinal flue gas outlet pipe 512.

[0024] In addition, the jet-suction type flue gas internal circulation device 5 is fixedly welded to the edge of the flue gas internal reflux suction port 4 through the end of the horizontal flue gas inlet pipe 511 and is arranged in the combustion-supporting air channel 3 of the burner throat 1.

[0025] During operation, the fuel gas is delivered by the fuel gas pipe 21 and supplied to each gas spray gun; the combustion-supporting air enters from the tail end of the burner throat 1 and flows forward in the combustion-supporting air channel 3, most of which flows forward around the outer periphery of the ejection-suction type flue gas internal circulation device 5, and is continuously accelerated due to the reduction of the flow area when flowing through each ejection-suction type flue gas internal circulation device 5, and a negative pressure is generated around the longitudinal flue gas outlet pipe 512, which can suck the gas in the pipe out into the combustion-supporting air channel 3; a small part is aligned with the port of the tapered tube of the Venturi-type tapered combustion-supporting air duct 52, flows in along the trend, is accelerated by the tapered flow of the tapered tube 521 to become a high-speed airflow, and then flows out through the straight pipe 522 and enters the longitudinal flue gas outlet pipe 512, and in the longitudinal A negative pressure is generated in the flue gas outlet pipe 512, which can suck the gas in the horizontal flue gas inlet pipe 511 into the longitudinal flue gas outlet pipe 512; thus, under the action of the double negative pressure, the flue gas outside the throat is sucked back into the longitudinal flue gas outlet pipe 512 through the horizontal flue gas inlet pipe 511, mixed with the high-speed combustion-supporting air from the straight pipe 522, and enters the combustion-supporting air channel under the suction of the negative pressure around the longitudinal flue gas outlet pipe 512, and merges with the majority of the continuously accelerating combustion-supporting air to form a mixed flue gas flow with a certain flow rate and a certain reduced oxygen content, which is sprayed forward into the furnace to participate in low-nitrogen combustion that helps to suppress and reduce the generation of NOx.

Claims

1. A flue gas internal circulation type low-nitrogen combustion device, the main body of which includes a burner throat (1), a gas channel (2) served by a gas pipe (21) connected to the intake end of a gas spray gun, and a combustion-supporting air channel (3) served by a burner throat annular cavity located outside the gas pipe (21). It is characterized in that it further includes a flue gas internal reflux suction port (4) arranged on the cavity wall of the burner throat (1) and a jet-suction type flue gas internal circulation device (5) arranged in the cavity of the burner throat (1), wherein: The main body of the burner throat (1) is cylindrical, and a gas channel (2) served by the gas pipe (21) is fixedly arranged at its axial center position. A plurality of the flue gas internal reflux suction ports (4) are arranged as required on the circular cavity wall near the tail end on the side close to the furnace wall (6); The jet-suction type flue gas internal circulation device (5) is fixedly arranged on the corresponding inner side wall of the burner throat (1) opposite to the flue gas internal reflux suction port (4), and includes an L-shaped smoke pipe (51) whose main body is formed by the intersection and interconnection of a horizontal flue gas inlet pipe (511) and a longitudinal flue gas outlet pipe (512), and a Venturi type tapered combustion-supporting air pipe (52) formed by the coaxial interconnection of a tapered pipe (521) and a straight pipe (522) inserted and fixed on the cavity wall at the L-shaped interconnection and intersection of the horizontal flue gas inlet pipe (511) and the longitudinal flue gas outlet pipe (512).

2. The flue gas internal circulation type low-nitrogen combustion device according to claim 1, It is characterized in that the jet-suction type flue gas internal circulation device (5) is fixedly arranged in the combustion-supporting air channel (3) of the burner throat (1) by welding the end of the horizontal flue gas inlet pipe (511) to the edge of the flue gas internal reflux suction port (4).

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