Combustor and combustion system

Abstract

The invention discloses a combustor and a combustion system.The combustor comprises a shell, a first-stage spray gun, an air channel and a second-stage spray gun, the first-stage spray gun, the air channel and the second-stage spray gun are arranged on the shell, mixed fuel comprises fuel and inert tail gas, and the mixed fuel sprayed out of the first-stage spray gun and air provided by the air channel are subjected to first-stage combustion; inert tail gas enables the mixing speed of fuel and oxygen to be reduced so as to reduce the combustion reaction speed, inert gas and residual air exchange heat with flames, the flame temperature is reduced, and then generation of NOx is reduced; mixed fuel sprayed by a second-stage spray gun and remaining air are subjected to second-stage combustion in a second combustion area, inert tail gas and circulating flue gas in the furnace dilute oxygen, the combustion reaction is slowed down, the surface area of a flame body is increased through staged combustion, the inert tail gas and the circulating flue gas in the furnace absorb and take away part of heat, local high temperature is eliminated, and the combustion efficiency is improved. And the generation of NOx is well inhibited.

Description

Technical Field

[0001] The present application belongs to the field of clean combustion technology, and specifically relates to a burner and a combustion system. Background Art

[0002] NOx is generated during the combustion of fuel. NOx is a general term for nitrogen oxides, mainly NO and NO2. The burners in the prior art mainly reduce the oxidation reaction of nitrogen by reducing the amount of air entering the burner or injecting steam, which can usually reduce the NOx generation to 100mg / Nm 3 In the case where the cracking furnace is not equipped with an SCR (Selective Catalytic Reduction technology, SCR for short) module to reduce the emission of NOx, the emission of NOx cannot meet the increasingly stringent emission standards of atmospheric pollutants. Therefore, it is urgent to design a burner and a combustion system to reduce the generation of NOx. Summary of the invention

[0003] In order to solve the problem, the burner in the prior art usually controls the NOx generation to 100mg / Nm 3 In order to solve the technical problem that the NOx emission cannot meet the increasingly stringent atmospheric pollutant emission standards when the cracking furnace is not equipped with SCR, the present application provides a burner and a combustion system.

[0004] In a first aspect, the present application provides a burner, which is arranged in a furnace body of a cracking furnace, and the burner includes a shell, and a primary spray gun, an air channel and a secondary spray gun arranged on the shell; the shell is arranged at the inlet of the furnace body, the input ends of the primary spray gun and the secondary spray gun are both used to receive the mixed fuel, and the output ends of the primary spray gun and the secondary spray gun are both facing the top of the furnace body; the air channel is arranged between the primary spray gun and the secondary spray gun, and the outlet of the air channel faces the top of the furnace body.

[0005] Compared with the prior art, the burner provided in this application has the following beneficial effects:

[0006] The burner provided in the present application has an air channel arranged between the first-stage spray gun and the second-stage spray gun. The air provided by the air channel will first mix with the mixed fuel sprayed by the first-stage spray gun, so that the first-stage spray gun first performs first-stage combustion to form a first combustion zone. During the first-stage combustion, the inert exhaust gas in the mixed fuel reduces the mixing speed of the fuel and oxygen to reduce the combustion reaction speed. The inert gas and the remaining air reduce the flame temperature by heat exchange with the flame, thereby reducing the generation of NOx. Subsequently, the mixed fuel sprayed by the second-stage spray gun and the remaining air provided by the air channel perform second-stage combustion to form a second combustion zone located above and around the first combustion zone. During the second-stage combustion, the flue gas generated by the combustion circulates in the furnace body. The combined action of the inert exhaust gas and the circulating flue gas in the furnace dilutes the oxygen, further reduces the oxygen concentration, slows down the combustion reaction, and the staged combustion of the first-stage combustion and the second-stage combustion increases the surface area of ​​the flame body. The inert exhaust gas and the circulating flue gas in the furnace absorb and take away part of the heat, eliminate local high temperature, and well suppress the generation of NOx.

[0007] In some embodiments, the burner further comprises a wind shield, wherein the wind shield is disposed on the top of the shell, and an annular space between the wind shield and the first-stage spray gun forms the air passage; the second-stage spray gun is disposed on the periphery of the wind shield.

[0008] In some embodiments, a plurality of the secondary spray guns are provided, and the plurality of the secondary spray guns are arranged around the periphery of the wind shield.

[0009] In a second aspect, the present application provides a combustion system, comprising a mixer, a cracking furnace and the burner according to the first aspect;

[0010] The mixer is used to mix the input inert tail gas with the input fuel, and transport the generated mixed fuel to the cracking furnace;

[0011] The cracking furnace includes a furnace body, an inert tail gas pipeline is arranged between the outlet of the furnace body and the mixer, and the inert tail gas generated in the furnace body is transported to the mixer through the inert tail gas pipeline; a first combustion zone and a second combustion zone are arranged in the furnace body, and the mixed gas sprayed by the first-level spray gun and the air transported by the air channel are subjected to primary combustion in the first combustion zone; the mixed gas sprayed by the second-level spray gun and the air transported by the air channel are subjected to secondary combustion in the second combustion zone, and the second combustion zone is located above and outside the first combustion zone.

[0012] Compared with the prior art, the combustion system provided in this application has the following beneficial effects:

[0013] In a combustion system with the above-mentioned burner, during the first-stage combustion process, the inert exhaust gas in the mixed fuel reduces the mixing speed of the fuel and oxygen to reduce the combustion reaction speed, and the inert gas and the remaining air reduce the flame temperature by heat exchange with the flame, thereby reducing the generation of NOx; during the second-stage combustion process, the flue gas generated by the combustion circulates in the furnace body, and the combined effect of the inert exhaust gas and the flue gas circulating in the furnace dilutes the oxygen, further reducing the oxygen concentration and slowing down the combustion reaction. The staged combustion of the first-stage combustion and the second-stage combustion increases the surface area of ​​the flame body, and the inert exhaust gas and the flue gas circulating in the furnace absorb and take away part of the heat, eliminating local high temperature, so that the generation of NOx is well suppressed.

[0014] In some embodiments, the system further comprises a compressor disposed on the inert tail gas pipeline, wherein the compressor is used to compress the inert tail gas to a pressure reaching a fuel intake pressure.

[0015] In some embodiments, it further includes an air supply device and a flame retardant, wherein the air supply device is in communication with the mixer and is used to provide fuel gas to the mixer; and the flame retardant is disposed between the air supply device and the flame retardant.

[0016] In some embodiments, at least one burner is provided; the combustion system further comprises a feed pipeline, one end of which is connected to the mixer, and the other end of which is connected to at least one burner.

[0017] In some embodiments, the mixing ratio of the fuel gas to the inert tail gas in the mixed fuel is 0.5-2.

[0018] In some embodiments, the ratio of the volume of the mixed fuel sprayed by the secondary spray gun to the volume of the mixed fuel sprayed by the primary spray gun is 2-4.

[0019] In some embodiments, the injection of the secondary lance forms an induced emission effect in the second combustion zone to guide the flue gas in the cracking furnace into the mixed fuel for secondary combustion. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A schematic diagram of the structure of a burner in one or more embodiments of the present application is shown;

[0021] Figure 2 A schematic diagram of the structure of a combustion system in one or more embodiments of the present application is shown;

[0022] Figure 3 A schematic structural diagram of a burner and related structures in a cracking furnace of a combustion system in one or more embodiments of the present application is shown.

[0023] Description of reference numerals:

[0024] 1-cracking furnace, 11-furnace body, 111-first combustion zone, 112-second combustion zone, 12-burner, 121-shell, 122-first-stage spray gun, 123-air channel, 124-second-stage spray gun, 125-wind shield; 2-mixer; 3-inert tail gas pipeline; 4-compressor; 5-flame retardant; 6-gas supply device; 7-furnace circulating flue gas; 8-feed pipeline. DETAILED DESCRIPTION

[0025] In order to make the technical personnel in the technical field to which the present application belongs to understand the present application more clearly, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0026] In the relevant technology, NOx refers to the general term for nitrogen oxides, mainly NO and NO2. According to the different NOx generation mechanisms, it can be divided into fuel type, rapid type, and thermal type. Fuel type NOx is generated by the oxidation of nitrogen compounds contained in the fuel during the combustion process, mainly generated in the initial stage of fuel combustion; rapid type NOx refers to the rapid generation of NOx near the reaction zone when hydrocarbon fuel is burned. If the fuel is too concentrated, rapid type NOx will only occur in the case of rich combustion (more hydrocarbon CH and relatively low oxygen concentration), and its generation generally accounts for less than 5% of the total nitrogen oxide generation; thermal type NOx is generated by the oxidation of nitrogen in the air at high temperature. As the reaction temperature T increases, its reaction rate increases exponentially; when T is less than 1500℃, the generation of NO is very small, and when T is greater than 1500℃, the reaction rate increases by 12 to 7 times for every 100℃ increase in T. In tubular heating furnaces using fuel gas, NOx is mainly thermal type. The generation rate of thermal type NOx is closely related to the combustion temperature, so it is also called temperature type NOx. The embodiments of the present application are mainly designed to reduce the NOx emissions from a tubular heating furnace using fuel gas.

[0027] The embodiment of the present application provides a burner, which is arranged in the furnace body 11 of the cracking furnace 1, referring to Figure 1As shown, the burner includes a shell 121, and a primary spray gun 122, an air channel 123 and a secondary spray gun 124 arranged on the shell 121; the shell 121 is arranged at the entrance of the furnace body 11, and the input ends of the primary spray gun 122 and the secondary spray gun 124 are both used to receive the mixed fuel, and the output ends of the primary spray gun 122 and the secondary spray gun 124 are both toward the top of the furnace body 11; the air channel 123 is arranged between the primary spray gun 122 and the secondary spray gun 124, and the outlet of the air channel 123 is toward the top of the furnace body 11.

[0028] A burner provided in an embodiment of the present application has an air channel 123 disposed between a primary spray gun 122 and a secondary spray gun 124. The air provided by the air channel 123 is first mixed with the mixed fuel sprayed by the primary spray gun 122, so that the primary spray gun 122 first performs primary combustion to form a first combustion zone. During the primary combustion, the inert tail gas in the mixed fuel reduces the mixing speed of the fuel and oxygen to reduce the combustion reaction speed. The inert gas and the remaining air reduce the flame temperature by heat exchange with the flame, thereby reducing the generation of NOx. Subsequently, the mixed fuel sprayed by the secondary spray gun 124 and the remaining air provided by the air channel 123 perform secondary combustion to form a second combustion zone located above and around the first combustion zone. During the secondary combustion, the flue gas generated by the combustion circulates in the furnace body. The combined action of the inert tail gas and the circulating flue gas in the furnace dilutes the oxygen, further reduces the oxygen concentration, slows down the combustion reaction, and the staged combustion of the primary combustion and the secondary combustion increases the surface area of ​​the flame body. The inert tail gas and the circulating flue gas in the furnace absorb and take away part of the heat, eliminate the local high temperature, and well suppress the generation of NOx.

[0029] In some embodiments, Figure 1 As shown, the burner 12 further includes a windshield 125, which is disposed on the top of the housing 121, and an annular space between the windshield 125 and the primary spray gun 122 forms an air passage 123; the secondary spray gun 124 is disposed on the periphery of the windshield 125. The air passage 123 is formed by the annular space between the windshield 125 and the primary spray gun 122, so that the air is first burned with the mixed gas sprayed from the primary spray gun 122, and then burned with the mixed gas sprayed from the secondary spray gun 124, so that the air concentration of the secondary combustion is low, and the combustion reaction of the secondary combustion can be slowed down.

[0030] In some embodiments, a plurality of secondary spray guns 124 are provided, and the plurality of secondary spray guns 124 are arranged around the periphery of the wind shield 125. Figure 1As shown, multiple secondary spray guns 124 are arranged along a circle on the periphery of the wind shield 125. The volume of the mixed fuel sprayed by the multiple secondary spray guns 124 is larger than the volume of the mixed fuel sprayed by the primary spray gun 122, so that most of the mixed fuel gas can participate in the secondary combustion, while less air participates in the secondary combustion, so that the combustion reaction of the secondary combustion is slowed down, and the generation of NOx is well suppressed.

[0031] Based on the above-mentioned burner, an embodiment of the present application also provides a combustion system. Figure 2 A schematic diagram of the structure of a combustion system in one or more embodiments of the present application is shown, referring to Figure 1-Figure 3 The combustion system comprises a cracking furnace 1, a mixer 2 and a burner 12, wherein:

[0032] The mixer 2 is used to mix the input inert tail gas with the input fuel, and transport the generated mixed fuel to the cracking furnace 1;

[0033] The cracking furnace 1 includes a furnace body 11, a burner 12 is arranged at the entrance of the furnace body 11, and the input ends of the primary spray gun 122 and the secondary spray gun 124 of the burner 12 are both connected to the mixer 2 for receiving the mixed fuel. The mixed gas sprayed by the primary spray gun 122 and the air transported by the air channel 123 are subjected to primary combustion in the first combustion zone 111; the mixed gas sprayed by the secondary spray gun 124 and the air transported by the air channel 123 are subjected to secondary combustion in the second combustion zone 112, and the second combustion zone 112 is located above and outside the first combustion zone 111.

[0034] In this embodiment, the burner 12 receives the mixed fuel and the input air, and then burns them. The flue gas generated by the combustion circulates in the furnace body 11. The burner 12 forms a flame in the first combustion zone 111 and the second combustion zone 112, which can increase the surface area of ​​the flame, increase the contact area between the flame and the inert exhaust gas and the circulating flue gas 7 in the furnace, so that the inert exhaust gas and the circulating flue gas 7 in the furnace absorb more heat from the flame, eliminate local high temperature, and effectively suppress the generation of NOx. The air first reaches the first combustion zone 111 for primary combustion and then enters the second combustion zone 112. Figure 3 As shown, the first combustion zone 111 is located in the air enrichment zone, and the second combustion zone 112 is located in the graded gas mixing zone in the figure. The injection of the secondary spray gun 124 forms an induced effect near the second combustion zone, and the flue gas in the furnace is drained into the fuel gas for secondary combustion, that is, combustion is carried out in the oxygen-poor zone. The flue gas generated by the combustion circulates in the furnace body 11. Under the joint action of the inert exhaust gas and the circulating flue gas 7 in the furnace, the oxygen concentration is further reduced, the combustion reaction is slowed down, the surface area of ​​the flame body is increased, and the inert exhaust gas and the circulating flue gas 7 in the furnace absorb and take away part of the heat, eliminating the local high temperature, so that the generation of NOx is well suppressed.

[0035] The present embodiment provides a combustion system, in which, in the first combustion zone 111, typically 30% of the mixed fuel (within the range of 20%-40%) is mixed with 100% of the combustion-supporting air. The inert exhaust gas mixed in the mixed fuel reduces the mixing speed of the fuel and oxygen, which can reduce the combustion reaction rate. Due to the effect of heat exchange, the inert gas and the remaining air that does not participate in the primary combustion reduce the flame temperature and the combustion reaction rate, thereby reducing the generation of NOx. In the second combustion zone 112, the remaining 70% of the mixed fuel is mixed with air for secondary combustion. The stability of the operation of the burner 12 of the present invention depends on the combustion stability of the first combustion zone 111. The stability of the first combustion zone 111 provides conditions for stable combustion in the second combustion zone 112. Most of the fuel is burned in the second combustion zone 112 through diversion. An induced effect is formed near the second combustion zone 112. The flue gas in the furnace is diverted to the fuel gas for secondary combustion, that is, combustion in the oxygen-poor zone. Under the joint action of the inert tail gas and the circulating flue gas 7 in the furnace, the oxygen concentration is further reduced, the combustion reaction slows down, the surface area of ​​the flame body is increased, and the inert tail gas and the circulating flue gas 7 in the furnace absorb and take away part of the heat, eliminating local high temperature, so that the generation of NOx is well suppressed. Stable combustion means that the flame has stability. The stability of the flame means that in a continuous stable combustion system, the flame propagation speed is equal to the flow speed of the combustible gas, and the shape of the combustion flame is straight and powerful without floating.

[0036] In some embodiments, an inert tail gas pipeline 3 is provided between the outlet of the furnace body 11 and the mixer 2 , and the inert tail gas generated in the furnace body 11 is transported to the mixer 2 through the inert tail gas pipeline 3 .

[0037] In some other embodiments, the inert exhaust gas may also come from other sources, as long as the gas input into the mixer is an inert gas that can reduce the mixing speed of the fuel and oxygen.

[0038] In some embodiments, the mixing ratio of the fuel gas to the inert exhaust gas in the mixer 2 is 0.5 to 2. As shown in the following table, the NOx content obtained after setting different mixing ratios, the NOx content can be reduced to 40 mg / Nm by setting the mixing ratio of the fuel gas to the inert exhaust gas in the mixer 2 to 0.5. 3 , compared with the existing burner 12, it has been greatly reduced, and according to the table, increasing the proportion of inert exhaust gas is conducive to further reducing the NOx content. Therefore, the proportion of inert exhaust gas can be appropriately increased in actual application.

[0039]

[0040] In some embodiments, Figure 1As shown, the burner 12 further includes a windshield 125, which is disposed above the housing 121, and an annular space between the windshield 125 and the primary spray gun 122 forms an air passage 123; the secondary spray gun 124 is disposed at the periphery of the windshield 125. The air passage 123 is formed by the annular space between the windshield 125 and the primary spray gun 122, so that the air is first burned with the mixed gas sprayed from the primary spray gun 122, and then burned with the mixed gas sprayed from the secondary spray gun 124, so that the air concentration in the second combustion zone 112 is low, and the combustion reaction of the secondary combustion can be slowed down.

[0041] In some embodiments, a plurality of secondary spray guns 124 are provided, and the plurality of secondary spray guns 124 are arranged around the periphery of the wind shield 125. Figure 1 As shown, a plurality of secondary spray guns 124 are arranged along a circle on the periphery of the wind shield 125. The volume of the mixed fuel sprayed by the plurality of secondary spray guns 124 is greater than the volume of the mixed fuel sprayed by the primary spray gun 122, so that most of the mixed fuel gas can enter the second combustion zone 112, and the second combustion zone 112 has less air, so that the combustion reaction in the second combustion zone 112 is slowed down, and the generation of NOx is well suppressed.

[0042] In some other embodiments, multiple secondary spray guns 124 can be arranged along multiple circles and arranged around the periphery of the wind shield 125 to form three-stage combustion, four-stage combustion... or even more stages of combustion, which can increase the surface area of ​​the flame to a greater extent, and the inert exhaust gas and the circulating flue gas 7 in the furnace absorb and take away more heat, so that the generation of NOx is further suppressed.

[0043] In some embodiments, the injection of the secondary lance 124 forms an ejection effect in the second combustion zone 112 to guide the flue gas in the cracking furnace 1 into the mixed fuel for secondary combustion. The injection of the secondary lance 124 guides the circulating flue gas 7 in the furnace into the mixed fuel. Under the joint action of the inert tail gas and the circulating flue gas 7 in the furnace, the oxygen is diluted, so that the oxygen concentration is further reduced, the combustion reaction is slowed down, the surface area of ​​the flame is increased, and the contact area between the flame and the inert tail gas and the circulating flue gas 7 in the furnace is increased, so that the inert tail gas and the circulating flue gas 7 in the furnace absorb more heat from the flame, eliminate local high temperature, and well suppress the generation of NOx.

[0044] In some embodiments, Figure 2 As shown, the combustion system also includes a compressor 4 arranged on the inert tail gas pipeline 3, and the compressor 4 is used to compress the inert tail gas to make its pressure reach the fuel intake pressure. The combustion system only needs to add one compressor 4 to compress the inert tail gas to make its pressure reach the fuel intake pressure, and the rest can be operated by utilizing the potential of the internal equipment of the original system, with very little flow resistance loss, and the waste heat is utilized by the tail gas external circulation, which is highly efficient and energy-saving.

[0045] In some embodiments, Figure 2 As shown, the combustion system further includes a flame retardant 5 and a gas supply device 6. The gas supply device 6 is communicated with the mixer 2 and is used to provide gas to the mixer 2. The flame retardant 5 is arranged between the mixer 2 and the gas supply device 6. By arranging the flame retardant 5 between the mixer 2 and the gas supply device 6, the gas can be prevented from burning before entering the burner 12, thereby improving the safety and reliability of the system.

[0046] In some embodiments, at least one burner 12 is provided; the combustion system further comprises a feed pipeline 8, one end of the feed pipeline 8 is connected to the mixer 2, and the other end is connected to at least one burner 12. Figure 2 As shown, in this embodiment, two burners 12 are arranged, one end of the feed pipeline 8 is connected to the mixer 2 , and the other end of the feed pipeline 8 is connected to the two burners 12 , so that the mixed gas in the mixer 2 is diverted and transported to the two burners 12 .

[0047] Based on the above combustion system, the embodiment of the present application further provides a combustion method, which includes:

[0048] Step S1: mixing the inert tail gas discharged from the cracking furnace 1 with the input fuel through the mixer 2 to obtain a mixed fuel and supplying the mixed fuel to the cracking furnace 1;

[0049] Step S2: The mixed fuel sprayed by the primary spray gun 122 and the air provided by the air channel 123 are subjected to primary combustion in the first combustion zone 111, and heat is exchanged between the flame and the inert exhaust gas and the remaining air to reduce the flame temperature and the primary combustion reaction speed;

[0050] Step S3: The mixed fuel sprayed from the secondary spray gun 124 and the remaining air are subjected to secondary combustion in the second combustion zone 112. The furnace circulating flue gas 7 and the inert tail gas generated by the combustion dilute the oxygen concentration, thereby slowing down the combustion reaction.

[0051] The combustion method provided in this embodiment is as follows: the inert exhaust gas generated in the furnace body 11 is transported to the mixer 2, and the inert exhaust gas is mixed with fuel to obtain a mixed fuel. Part of the mixed fuel is subjected to primary combustion with sufficient air in the first combustion zone 111, and the inert exhaust gas reduces the mixing speed of the fuel and oxygen, thereby reducing the combustion reaction speed. The inert gas and the remaining air reduce the flame temperature due to the heat exchange effect, thereby reducing the generation of NOx; the remaining mixed fuel is subjected to secondary combustion with air in the second combustion zone 112, and under the combined action of the inert exhaust gas and the circulating flue gas 7 in the furnace, the oxygen concentration is further reduced, the combustion reaction is slowed down, and the staged combustion increases the surface area of ​​the flame body. The inert exhaust gas and the circulating flue gas 7 in the furnace absorb and take away part of the heat, thereby eliminating local high temperature and suppressing the generation of NOx.

[0052] In the present application, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0053] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise" and "counterclockwise" indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0054] In this application, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0055] In addition, the descriptions of "first", "second", etc. in this application are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0056] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the claims and their equivalents.

Claims

1. A burner, arranged in a furnace body of a cracking furnace, characterized in that: It comprises a housing, and a primary spray gun, an air channel and a secondary spray gun arranged on the housing, wherein: The shell is arranged at the entrance of the furnace body, the input ends of the primary spray gun and the secondary spray gun are both used to receive the mixed fuel, and the output ends of the primary spray gun and the secondary spray gun are both facing the top of the furnace body; the air channel is arranged between the primary spray gun and the secondary spray gun, and the outlet of the air channel faces the top of the furnace body.

2. The burner according to claim 1, characterized in that The burner further comprises a wind shield, which is arranged on the top of the shell, and the annular space between the wind shield and the first-stage spray gun forms the air channel; The secondary spray gun is arranged on the periphery of the wind shield.

3. The burner according to claim 2, characterized in that: There are multiple secondary spray guns, and the multiple secondary spray guns are arranged around the periphery of the wind shield.

4. A combustion system, characterized in that: The invention comprises a mixer, a cracking furnace and a burner according to any one of claims 1 to 3, wherein: The mixer is used to mix the input inert tail gas with the input fuel; The cracking furnace comprises a furnace body, the burner is arranged at the inlet of the furnace body, and the input ends of the primary spray gun and the secondary spray gun of the burner are both connected to the mixer.

5. The combustion system according to claim 4, characterized in that: An inert tail gas pipeline is arranged between the outlet of the furnace body and the mixer.

6. The combustion system according to claim 4, characterized in that: The system also includes a compressor disposed on the inert tail gas pipeline, and the compressor is used to compress the inert tail gas to make its pressure reach the fuel intake pressure.

7. The combustion system according to claim 4, characterized in that: It also includes an air supply device and a flame retardant. The air supply device is communicated with the mixer and is used to provide fuel gas to the mixer. The flame retardant is arranged between the air supply device and the flame retardant.

8. The combustion system according to claim 4, characterized in that: At least one burner is provided; the combustion system further comprises a feed pipeline, one end of which is connected to the mixer, and the other end of which is connected to at least one burner.

9. The combustion system according to any one of claims 4 to 8, characterized in that: The mixing ratio of the fuel gas to the inert tail gas in the mixed fuel is 0.5-2.

10. The combustion system according to any one of claims 4 to 8, characterized in that: The ratio of the volume of the mixed fuel sprayed by the secondary spray gun to the volume of the mixed fuel sprayed by the primary spray gun is 2-4.

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