Low nox short flame ethylene cracking furnace burner

Abstract

The utility model relates to a kind of low NOx short flame ethylene cracking furnace combustor, including air bellow, firebrick, gas collector, staged fuel gas branch pipe, primary nozzle, secondary nozzle and air distributor, each staged fuel gas branch pipe connects primary nozzle and secondary nozzle, the primary nozzle enters the intermediate combustion passageway in firebrick, the secondary nozzle is stretched out from firebrick periphery, the firebrick periphery is equipped with the fire-igniting inclined plane that converges inward to secondary nozzle, the firebrick top end surface is equipped with flame platform, the fire-igniting inclined plane is equipped with flat flame tunnel corresponding each secondary nozzle, the flat flame tunnel is set below flame platform, the flat flame tunnel is through in and out radially to firebrick.The utility model reduces NOx, optimizes air by air distributor, changes fuel injection and flame structure, to reduce flame length, the height of flame is dynamically fed back by CO probe, real-time monitoring is carried out to the height of flame, ensure combustion stability.

Description

Technical Field

[0001] This utility model relates to the field of petrochemical equipment technology, specifically to a low-NOx short-flame ethylene cracking furnace burner. Background Technology

[0002] Traditional ethylene cracking furnace burners suffer from problems such as excessively long flames, high NOx emissions (typically >80 mg / m³), and low radiative heat transfer efficiency. While the existing technology CN205227328U reduces NOx through staged combustion, its flame length is more than 15% longer than that of traditional burners. This leads to uncontrolled flame tip curling, which can touch the furnace tubes, reducing tube life, shortening the cracking furnace's operating cycle, and creating difficulties in operating the heating furnace. Therefore, there is an urgent need to design a low-NOx, short-flame ethylene cracking furnace burner that achieves high efficiency and energy saving through optimized air distribution, fuel injection, and flame structure. Utility Model Content

[0003] The purpose of this invention is to overcome the above-mentioned shortcomings and provide a low-NOx short-flame ethylene cracking furnace burner. While reducing NOx, it optimizes air through an air distributor, changes fuel injection and flame structure, thereby reducing flame length. It also dynamically feeds back flame height through a CO probe and monitors flame height in real time to ensure combustion stability.

[0004] The purpose of this utility model is achieved as follows:

[0005] A low-NOx short-flame ethylene cracking furnace burner includes a wind box, refractory bricks, a gas collecting pipe, staged fuel gas branch pipes, a primary nozzle, a secondary nozzle, and an air distributor. The refractory bricks are located at the top of the wind box, and the air distributor is located at the center of the refractory bricks. The gas collecting pipe connects to each staged fuel gas branch pipe, which extends upward from the bottom of the wind box into the refractory bricks. Each staged fuel gas branch pipe connects to a primary nozzle and a secondary nozzle. The primary nozzle enters the intermediate combustion channel within the refractory brick, and the secondary nozzle extends from the periphery of the refractory brick. The periphery of the refractory brick has an inwardly converging ignition slope corresponding to the secondary nozzle. The top surface of the refractory brick has a flame platform, and the ignition slope has a flat flame tunnel corresponding to each secondary nozzle. The flat flame tunnel is located below the flame platform and penetrates the refractory brick radially inward and outward.

[0006] Preferably, the staged fuel gas branch pipes are evenly distributed around the circumference of the air box, and multiple primary nozzles are evenly distributed around the circumference outside the air distributor and inside the refractory bricks, with each secondary nozzle corresponding to a primary nozzle.

[0007] Preferably, the height of the flat flame tunnel is 5-10mm, and some of the primary flames enter the flat flame tunnel after being blocked by the flame platform.

[0008] Preferably, the air distributor has a flared structure and includes a lower straight pipe, an upper conical pipe, and a perforated plate connected in sequence.

[0009] Preferably, the upper conical tube is connected to a perforated plate at its large diameter opening, and the flaring angle of the upper conical tube is 20-40°.

[0010] Preferably, the porous plate array has multiple through holes.

[0011] Preferably, multiple furnace CO probes are arranged vertically along the furnace wall.

[0012] Preferably, the nozzle of the primary nozzle faces the inner wall of the refractory brick, and the nozzle of the secondary nozzle faces the ignition slope on the outer periphery of the refractory brick.

[0013] Preferably, the nozzle cross-section of the secondary nozzle is flat, and the fuel gas is ejected in a flat fan shape.

[0014] Preferably, the primary nozzle and the secondary nozzle are made of 310SS stainless steel.

[0015] The beneficial effects of this utility model are:

[0016] 1. Composite flame stabilization structure: Refractory bricks integrate a flame platform and a flat flame tunnel. Some of the primary flames are blocked by the flame platform and enter the flame tunnel, providing a stable ignition source for the secondary fuel (experiments show that the ignition delay time is reduced by 40%).

[0017] 2. Adjustable air distributor: The flared structure combined with the perforated plate distributes the combustion air into an annular airflow, which mixes with the fuel gas fully and efficiently;

[0018] 3. Fan-shaped secondary fuel injection system: The fuel gas nozzle of the secondary nozzle is flat, and the fuel gas is ejected in a flat fan shape. The flat fan-shaped nozzle reduces the mixing time of fuel and combustion air to 0.3 seconds, which is 20% shorter than the traditional structure, and reduces the flame length by 10%.

[0019] 4. CO probe array flame monitoring: Six furnace CO probes are arranged vertically along the furnace wall to dynamically feed back the flame height through the concentration gradient distribution. Attached Figure Description

[0020] Figure 1 This is a three-dimensional structural diagram of a low-NOx short-flame ethylene cracking furnace burner according to the present invention.

[0021] Figure 2 for Figure 1 A magnified view of a portion of the image.

[0022] Figure 3 for Figure 2 A magnified view of a portion of the image.

[0023] Figure 4 This is a schematic diagram of the top structure of the refractory brick.

[0024] Figure 5 This is a schematic diagram of an air distributor.

[0025] Figure 6 This is a schematic diagram of the internal structure of a low-NOx short-flame ethylene cracking furnace burner according to the present invention.

[0026] in:

[0027] 1. Bellows; 1.1. Combustion air inlet; 2. Refractory bricks; 2.1. Intermediate combustion channel; 2.2. Ignition ramp; 2.3. Flame platform; 2.4. Flat flame tunnel; 3. Gas collecting pipe; 4. Staged fuel gas branch pipe; 5. Primary nozzle; 6. Secondary nozzle; 7. Air distributor; 7.1. Lower straight pipe; 7.2. Upper conical pipe; 7.3. Perforated plate; 8. Refractory material at the furnace bottom; 9. Furnace wall; 10. CO probe in the furnace chamber. Detailed Implementation

[0028] See Figure 1-6 This utility model relates to a low-NOx short-flame ethylene cracking furnace burner, comprising a wind box 1, refractory bricks 2, a gas collecting pipe 3, staged fuel gas branch pipes 4, a primary nozzle 5, a secondary nozzle 6, an air distributor 7, and a continuous lamp 8. The wind box 1 has a combustion air inlet 1.1 on its side. The gas collecting pipe 3 is located at the bottom of the wind box 1. The refractory bricks 2 are located at the top of the wind box 1. The air distributor 7 is located inside the refractory bricks 2 and is fixed to the center of the refractory bricks 2 by three evenly distributed stiffeners. One end of each stiffener is connected to the air distributor 7, and the other end is connected to the refractory bricks 2. The gas collecting pipe 3 connects to each staged fuel gas branch pipe 4, which are evenly distributed around the circumference of the wind box 1. The staged fuel gas branch pipes 4 originate from the bottom of the wind box 1. The refractory brick 2 extends upwards, and each staged fuel gas branch pipe 4 connects to a primary nozzle 5 and a secondary nozzle 6. Multiple primary nozzles 5 are evenly distributed circumferentially outside the air distributor 7 and inside the refractory brick 2. The secondary nozzles 6 correspond one-to-one with the primary nozzles 5. The primary nozzles 5 enter the intermediate combustion channel 2.1 inside the refractory brick 2. The secondary nozzles 6 extend from the periphery of the refractory brick 2. The periphery of the refractory brick 2 is provided with an inwardly converging ignition slope 2.2 corresponding to the secondary nozzles 6. The top surface of the refractory brick 2 is provided with a flame platform 2.3. The ignition slope 2.2 is provided with a flat flame tunnel 2.4 corresponding to each secondary nozzle 6. The flat flame tunnel 2.4 is located below the flame platform 2.3 and the flat flame tunnel 2.4 penetrates the refractory brick 2 radially inwards and outwards. The flat flame tunnel 2.4 has a height of 5-10mm. Some of the primary flames enter the flame tunnel 2.4 after being blocked by the flame platform 2.3, providing a stable ignition source for the secondary fuel (experiments show that the ignition delay time is reduced by 40%).

[0029] The air distributor 7 has a flared structure and includes a lower straight pipe 7.1, an upper conical pipe 7.2, and a perforated plate 7.3 connected in sequence. The larger diameter opening of the upper conical pipe 7.2 connects to the perforated plate 7.3. The flare angle of the upper conical pipe 7.2 is 20-40°. The perforated plate 7.3 has an array of multiple through holes, each with a diameter of 10 mm and a spacing of 20 mm. The air distributor 7 distributes the combustion air into an annular airflow, ensuring thorough and efficient mixing with the fuel gas.

[0030] The continuous lamp 8 is an important component for igniting and protecting the combustion. The continuous lamp 8 is inserted into the refractory brick 2 from the bottom of the bellows 1.

[0031] The bottom periphery of the refractory brick 2 is provided with furnace bottom refractory material 9 to ensure that the high temperature inside the furnace will not radiate out.

[0032] Six furnace CO probes 11 are arranged vertically along the furnace wall 10 to dynamically feed back the flame height through the concentration gradient distribution.

[0033] The primary nozzle 5 has its nozzle facing the inner wall of the refractory brick 2, while the secondary nozzle 6 has its nozzle facing the ignition ramp 2.2 on the outer periphery of the refractory brick 2. The nozzle cross-section of the secondary nozzle 5 is flat, and the fuel gas is ejected in a flat fan shape, with a fan width of 2 mm and a length of 5-12 mm. The flat fan-shaped nozzle shortens the mixing time of fuel and combustion air to 0.3 seconds, which is 20% shorter than the traditional structure, and reduces the flame length by 10%.

[0034] The refractory brick 2 has an Al2O3 content of more than 65%, which makes its refractoriness not less than 1650℃.

[0035] The primary nozzle 5 and the secondary nozzle 6 are made of 310SS stainless steel, which can operate continuously at high temperatures and help the burner to operate for a long period of time.

[0036] While reducing NOx, the system optimizes air through an air distributor, alters fuel injection and flame structure to reduce flame length, and dynamically monitors flame height in real time via a CO probe to ensure combustion stability. Overall energy savings are ≥1.5%, NOx emission reduction is ≥5% (measured below 72mg / m³), flame length is shortened by more than 10%, radiant heat flux is increased by 8.3%, combustion stability is improved by 40%, and operating cycle is extended by 20%.

[0037] In addition to the above embodiments, this utility model also includes other implementation methods. All technical solutions formed by equivalent transformation or equivalent substitution should fall within the protection scope of the claims of this utility model.

Claims

1. A low-NOx short-flame ethylene cracking furnace burner, characterized in that: The system includes a bellows, refractory bricks, a gas collecting pipe, graded fuel gas branch pipes, a primary nozzle, a secondary nozzle, and an air distributor. The refractory bricks are located on top of the bellows, and the air distributor is located at the center of the refractory bricks. The gas collecting pipe connects to each graded fuel gas branch pipe, which extends upward from the bottom of the bellows into the refractory bricks. Each graded fuel gas branch pipe connects to a primary nozzle and a secondary nozzle. The primary nozzle enters the central combustion channel within the refractory brick, and the secondary nozzle extends from the outer periphery of the refractory brick. The outer periphery of the refractory brick has an inwardly converging ignition slope corresponding to the secondary nozzle. The top surface of the refractory brick has a flame platform, and the ignition slope has a flat flame tunnel corresponding to each secondary nozzle. The flat flame tunnel is located below the flame platform and penetrates the refractory brick radially inward and outward.

2. The low-NOx short-flame ethylene cracking furnace burner according to claim 1, characterized in that: The staged fuel gas branch pipes are evenly distributed around the circumference of the air box, and multiple primary nozzles are evenly distributed around the circumference outside the air distributor and inside the refractory bricks. The secondary nozzles correspond one-to-one with the primary nozzles.

3. The low-NOx short-flame ethylene cracking furnace burner according to claim 1, characterized in that: The flat flame tunnel has a height of 5-10mm, and some of the primary flames enter the flat flame tunnel after being blocked by the flame platform.

4. The low-NOx short-flame ethylene cracking furnace burner according to claim 1, characterized in that: The air distributor has a funnel-shaped structure and includes a lower straight pipe, an upper conical pipe, and a perforated plate connected in sequence.

5. The low-NOx short-flame ethylene cracking furnace burner according to claim 4, characterized in that: The upper tapered tube is connected to a perforated plate at its large diameter opening, and the flaring angle of the upper tapered tube is 20-40°.

6. The low-NOx short-flame ethylene cracking furnace burner according to claim 4, characterized in that: The perforated plate array has multiple through holes.

7. The low-NOx short-flame ethylene cracking furnace burner according to claim 1, characterized in that: Multiple furnace CO probes are arranged vertically along the furnace wall.

8. The low-NOx short-flame ethylene cracking furnace burner according to claim 1, characterized in that: The nozzle of the primary nozzle faces the inner wall of the refractory brick, and the nozzle of the secondary nozzle faces the ignition slope on the outer periphery of the refractory brick.

9. A low-NOx short-flame ethylene cracking furnace burner according to claim 1, characterized in that: The nozzle cross-section of the secondary nozzle is flat, and the fuel gas is ejected in a flat fan shape.

10. A low-NOx short-flame ethylene cracking furnace burner according to claim 1, characterized in that: The primary and secondary nozzles are made of 310SS stainless steel.

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