Gas burner with incomplete pre-mixing of gas and air

Abstract

FIELD: gas combustion burners.SUBSTANCE: burners in which gaseous fuel is mixed with air before the combustion zone, used in the oil, chemical, petrochemical and other industries where high-temperature heating of hydrocarbon raw materials is required, or a high-temperature chemical reaction is carried out due to the heat released during the combustion of natural and oil refinery gases. A gas burner with incomplete preliminary mixing of gas and air, comprising a gas supply pipe connected by means of a flange joint to a gas chamber, a primary air mixing unit located inside the burner, having a space for the injection process and channels for supplying primary air, characterized in that the primary air mixing unit is a tightly fitting rim with rectangular openings located at an equal distance from each other outside the burner around the mixing unit, with a primary air supply regulator fixed on top of the rim, inside which, in a circle at an equal distance from each other, eight blades for mixing the primary air and gas are located, fixed on the inner rim; the blades are attached by means of a hook-and-eye connection to the surface of the adjustment rim and are connected to an adjustment mechanism consisting of an L-shaped plate located outside and fixed to a fixed support flange; a flame arrester is installed inside the burner, consisting of ribbed plates fixed on top of a hollow sleeve mounted on a flame gap regulator, which is a tube located in the center and passing inside through the entire surface of the burner, fixed on one side, and at the outlet of the burner connected to a disk distributor with an angle of inclination of 70°, on the outside of the burner there is a secondary air regulator, which is a metal rim located around the burner with protrusions for fixation, inside there are twenty-four blades located at an equal distance from each other, in the upper part of the secondary air regulator there is an opening for the passage of the gas supply pipe to the pilot burner through it, at the outlet of the gas supply pipe to the pilot burner there is a flame stabilizer installed.EFFECT: operational safety and improved gas-air mixing.4 cl, 7 dwg

Description

[0001] The invention relates to the field of gas combustion burners, in particular to burners in which gaseous fuel is mixed with air before the combustion zone, and can be used in the oil, chemical, petrochemical and other industries where high-temperature heating of hydrocarbon raw materials or the implementation of a high-temperature chemical reaction is required due to the heat released during the combustion of natural and oil refinery gases.

[0002] A burner with an adjustable air supply is known [RU Patent No. 233959, published on May 13, 2024], comprising a tube for introducing combustible gas into a mixing chamber, a mixing chamber, a Venturi nozzle at the outlet of the mixing chamber, a casing, characterized in that the casing is an outer and inner hollow cylinders installed around the burner so as to form an air channel in the form of a hollow cylinder, wherein the mixing chamber contains an annular channel for introducing air from the air channel and a mesh on the side of the combustible gas supply tube, wherein the casing is designed with the ability to regulate the air flow through the air channel by adjusting the relative position of the outer and inner cylinders. A distinctive feature of the burner is the reduction of noise from the burner with an adjustable air supply.

[0003] The disadvantages of the analog include the lack of preliminary gas supply adjustment and the lack of any means of reducing burner noise. In the described design, the burner is installed in the reactor, the gap between the cylinders is adjusted, gas is supplied through a tube, and the gas flow begins to draw air into the mixing chamber through the gap between the cylinders and the openings in the mixing chamber, igniting the gas mixture at the nozzle outlet. If a damper is present, the air supply can be fine-tuned. Burner noise is dampened by encountering multiple metal layers, primarily the double-layer cylinders, mesh, and tube.The end of the outer cylinder is sealed with a two-layer cover with an opening for the combustible gas inlet tube, the mixing chamber contains an annular channel for the air inlet from the air channel and a mesh on the side of the combustible gas inlet tube, the casing is designed with the ability to regulate the air flow through the air channel by adjusting the relative position of the outer and inner cylinders and this leads to inaccurate adjustment of the air supply, which reduces the efficiency of the burner and overheats the burner elements.

[0004] The prototype of the proposed invention is a full premix gas burner with variable modulation ranges [RU Patent No. 2749114, published on June 4, 2021]. The full premix modulating gas burner comprises a cylindrical body, plugged on one side and attached to the flange of the body on the other side, the forming surface of the burner body is made with openings for the outlet of a gaseous fuel mixture, the body is divided by an internal partition into two internal zones, the operation of one of which can be performed separately, the partition is connected to the cylinder and is configured to move longitudinally along the axis of the burner, a valve with a rod is installed in the internal partition, ensuring the passage of a gaseous fuel mixture between the internal zones of the cylindrical body.

[0005] The disadvantages of the prototype are the complexity of the design, requiring frequent maintenance, limited self-cleaning efficiency, and the valve opening is carried out by an electromechanical drive.

[0006] The technical problem of the invention is to create a gas burner with incomplete pre-mixing of gas and air, achieving the following technical results: operational safety and improved gas-air mixing. Fuel will burn more completely, which can be achieved through smooth regulation of the primary and secondary air swirl valves. This should lead to a reduction in gas consumption, thereby saving energy without sacrificing equipment power, and reducing nitrogen oxide (NOx) emissions. This increases the efficiency of the entire furnace equipment, and therefore the overall efficiency of the unit.

[0007] The claimed technical result is achieved in that in a gas burner with incomplete preliminary mixing of gas and air, containing a gas supply pipe connected by means of a flange joint to a gas chamber, a primary air mixing unit located inside the burner, having a space for the injection process and channels for supplying primary air, according to the invention, the primary air mixing unit is a tightly fitting rim with rectangular openings located at an equal distance from each other outside the burner around the mixing unit, with a primary air supply regulator fixed on top of the rim, inside which, in a circle at an equal distance from each other, eight blades for mixing primary air and gas are located, fixed on the inner rim;the blades are attached to the surface of the adjusting rim by means of a hook-and-eye connection and are connected to an adjusting mechanism consisting of an L-shaped plate located on the outside and secured to a fixed support flange; a flame arrester is installed inside the burner, consisting of ribbed plates secured on top of a hollow sleeve mounted on a flame gap regulator, which is a tube located in the center and passing inside through the entire surface of the burner, secured on one side, and at the outlet of the burner connected to a disk distributor with an inclination angle of 70°;On the outside of the burner there is a secondary air regulator, which is a metal rim located around the burner with protrusions for fixation, inside there are twenty-four blades located at the same distance from each other, in the upper part of the secondary air regulator there is an opening for the passage of the gas supply pipe to the pilot burner through it, at the outlet of the gas supply pipe to the pilot burner there is a flame stabilizer installed.

[0008] The technical result is achieved by incorporating a primary and secondary air mixing unit into the burner design. These design solutions simplify and improve burner operation compared to similar products, as the design does not require complex technical solutions, requires little maintenance, and routine equipment repairs are sufficient. No electromechanical actuator is required to open the burner valves. This solution is achieved by installing swirlers. Furthermore, the primary air unit allows for smoother adjustment using a dedicated adjustment mechanism.

[0009] Next, a structural element was added that functions as a flame arrester, ensuring safer operation. This is achieved by allowing the gas-air mixture to flow unimpeded in the desired direction and significantly impeding the reverse flow of the already ignited mixture. This solution reduces the likelihood of emergency situations that may arise from an uncontrolled flame escape into the burner and through the primary air intake ducts.

[0010] To improve flame distribution across the deck, it is proposed to increase the angle of the disc distributor compared to similar designs. This will ensure more stable combustion and minimize uncontrolled combustion, when flames bypass the disc distributor due to improper adjustment and instead strike the pipes. It is also recommended to strengthen the fastening of the refractory material on the disc distributor, as when exposed to high temperatures, the fastened refractory material may fall off, causing the disc distributor to lose some of its effectiveness. This can be remedied by adding additional fasteners, staggering them, and securing them together with refractory wire.

[0011] The next component proposed for modernization pertains to the pilot burner. It is an integral component of the design and continuously burns, thereby igniting and maintaining combustion of the main burner. The main burner, in turn, is a device under development designed to more completely combust gaseous fuel mixed with air, ensuring heating of the product passing through the furnace coils by transferring radiant energy received from the flame and reflected from the furnace floor. To stabilize the flame, directing it toward maintaining combustion of the main burner, and to minimize the possibility of flame knockout and preventing contact with the walls of the sleeve and the exterior of the burner, a simple yet highly effective element will be used, acting as a flame equalizer and tightly connected to the gas supply channel to the pilot burner.

[0012] Swirl of primary air and gas in burners without prior mixing of the gas and air can improve equipment efficiency by intensifying the mixture formation process. This is achieved by swirling the air and fuel mixture flows, increasing the velocity gradients between the outflowing streams and the surrounding environment. Flow swirl is achieved using special devices built into the burners. Special blades impart a rotational motion to the air flow, causing the gas to intersect in the swirling air flow in small streams, creating a well-mixed gas-air mixture. This improves gas-air mixing, intensifying oxidation reactions, increasing fuel burnout, and reducing the flame length—this is important, as flame length determines the path through which gas-air mixing is completed.

[0013] The degree of gas-air mixing in the burner affects the reduction of nitrogen oxide emissions. One way to reduce nitrogen oxide formation is to dilute the fuel before it reaches the flame zone. This is achieved by high-velocity fuel jets drawing in combustion products and mixing with them, forming a mixed gas-air mixture. As a result, the fuel becomes more diluted, reducing nitrogen oxide formation.

[0014] Fig. 1 shows the external appearance of the gas burner, Fig. 2 - a diagram of the primary air swirler regulator of the gas burner, Fig. 3 - a diagram of the external swirlers of the gas burners, Fig. 4 - a diagram of the disk distributor of the gas burner, Fig. 5 - a diagram of the flame arrester of the gas burner, Fig. 6 - a general view of the swirlers of the gas burners, Fig. 7 - a diagram of the flame stabilizer of the pilot gas burner.

[0015] The gas burner consists of the following elements: a gas supply pipe 1, connected by means of a flange joint to a gas chamber 2, which has a pair of nozzles 3 that provide gas injection into the mixing chamber.

[0016] The primary air mixing unit is located inside the burner, has a space 4 for the injection process and channels 5 for the primary air supply. It consists of a tight-fitting rim with rectangular holes located at equal distances from each other outside the burner, surrounding the mixing unit. A corresponding regulator 6 is attached to the top of the rim for easy adjustment. Further inside the structure, eight blades 7 for mixing the primary air and gas are arranged in a circle at equal distances from each other. They are fixed to the inner rim 8, which has drilled holes for mounting studs 9. Adjustment rim 10 has a hook 11 to which an eye 12 is attached, located at the bottom of blade 7, thereby connecting blades 7 and the adjustment mechanism. It consists of an L-shaped plate 13 located outside the structure, fixed to a fixed support flange 14 using fastening pins 15.The L-shaped plate 13 has a hole in its upper part that allows for fastening a narrow adjusting plate 16, connected on the other side to the adjusting rim 10. A fastening bolt 17 is inserted into the hole in the L-shaped plate 13 and the hole for fastening the adjusting plate 16. This allows the adjusting plate 16 to move along the hole in the L-shaped plate 13 in the direction away from or toward the support flange 14. Due to this, the desired swirl of the blades 7 is set by connecting the hook 11 and the eye 12; after adjustment, the fastening bolt 17 is fixed with nuts and washers in the lower and upper parts.

[0017] Further installed within the burner are ribbed plates 18, which form part of flame arrester 19. They are secured above a hollow bushing 20, which has screw-on nuts on both ends to secure the structure. This bushing is mounted on flame gap adjuster 21. This adjuster is a tube located centrally and extends internally across the entire burner surface. At one end, flame gap adjuster 21 is secured with a nut, and at the burner outlet, it connects to disk distributor 22, which consists of a uniform layer of heat-resistant material 23 applied to its surface. This material is secured with metal refractory fasteners 24, arranged in a staggered pattern and held together with refractory wire 25.

[0018] On the outside of the burner is a secondary air regulator 26. This is a metal ring around the burner with small protrusions for fixation. Further inside are twenty-four equally spaced secondary air flow vanes 27, which are attached to an outer ring 28, which has holes for attaching adjustment pins 29, which are connected by bolts 30 to a sleeve 31.

[0019] A hole is also drilled in the upper portion of secondary air regulator 26 for passage of pipe 32, which supplies gas to the pilot burner. The gap between the walls of sleeve 31 and the outer part 33 of the burner can be tightly sealed using secondary air regulator 26. Flame stabilizer 34 is installed at the outlet of pipe 32, which supplies gas to the pilot burner. This flame stabilizer consists of a sleeve with drilled holes 35 and is connected to pipe 32 using a tight-fitting special nut 36 with a gasket.

[0020] Centralizers 37, which are narrow guide plates attached to the flame gap regulator tube 21, are installed within the burner and sleeve. The burner is secured to the fixed support flange 14 by plates 38, mounted above and below the outer portion 33 of the burner, using mounting studs 39. The burner is equipped with a control and measuring device. A flame control pipe 41 with a flame control sensor 42 is installed within the space for the flame control sensor 40. The burner assembly is mounted within a burner block 43 made of refractory material, the primary purpose of which is to provide stable thermal insulation from high-temperature exposure and the required flame angle.

[0021] The gas burner works as follows.

[0022] Gas passes through gas supply pipe 1 and enters gas chamber 2, where nozzles 3 inject gas into the mixing chamber. Thanks to the injection space 4, air is drawn in through corresponding primary air supply channels 5, which have a primary air regulator 6, which allows the amount of air supplied for mixing to be increased or decreased. The resulting gas-air mixture is then thoroughly mixed by primary air swirlers. The required turbulence is created by vanes 7, which are spaced at equal distances from one another. They are fixed inside the burner on an inner rim 8, which is inclined at an angle between the vanes 7 to remove any unnecessary obstructions to the flow, and are secured with mounting pins 9.The blades 7 are attached to the surface of the adjusting rim 10 using a hook 11 and an eye 12 (hook-eye connection), thereby changing the degree of opening and closing, which affects the swirl. By means of an adjustment mechanism located outside the burner, which is an L-shaped plate 13, fixed to the support flange 14 of the burner, with the help of fastening studs 15. At the top of the plate 13 there is the space necessary for adjustment, to which the adjusting plate 16 is attached, fastened with the adjusting rim 10. In order to change the degree of swirl of the blades, it is necessary to loosen the fastening bolt 17 from above the L-shaped plate 13, connecting the adjusting plate 16, pulling it in the direction towards or away from the support flange 14. This will set the adjusting rim 10 in motion, and the hook 11 will pull the eye 12, fixed in the middle at the bottom of the blade. Smooth adjustment occurs, since the blades 7 are fastened on the sleeve with a bolt to the inner rim 8.This provides the necessary flow velocity through the channels between the ribbed plates 18 of the flame arrester 19, secured to the sleeve 20 with the flame gap regulator 21. The resulting mixed gas-air mixture is uniformly fed to the disc distributor 22, which, in turn, has a larger angle of inclination of approximately 70 degrees, allowing the flame to be directed directly onto the surface of the matting to transfer radiant energy to the product coil. It also contains a heat-resistant material 23, reinforced by staggered fasteners 24, secured together with refractory wire 25. To maintain combustion and ensure complete fuel combustion, a secondary air supply is required; it is increased or decreased using the secondary air regulator 26. The incoming air flow from the secondary air regulator 26 passes through the secondary air swirlers.They consist of pre-adjusted blades 27, which are secured to outer rim 28 by adjusting pins 29 before burner startup. Rim 28 is attached to sleeve 31 by connecting bolts 30, allowing the swirl angle to be adjusted without removing the entire burner. This increases the air flow velocity, and the secondary air swirl ensures more complete combustion of the fuel within the furnace. In addition to the secondary air swirl vanes, a pipe 32 for feeding gas to the pilot burner runs above. To stabilize the flame, directing it toward the main burner's combustion process and to prevent it from wandering or touching the walls of sleeve 31 and the outer part 33 of the burner, a flame stabilizer 34 is installed at the outlet of the pipe. It is a sleeve with holes 35, from where the air necessary for combustion comes, connected to the pipe using a special nut 36 and a gasket that ensures a tight connection.Centralizers 37 are installed inside the burner and in its sleeve, ensuring proper burner installation. The burner is secured to the support flange 14 using plate 38 and mounting studs 39. Flame control pipe 41, with flame control sensor 42, is installed in the space for flame control sensor 40. The burner assembly is installed in burner stone 43.

Claims

1. A gas burner with incomplete preliminary mixing of gas and air, comprising a gas supply pipe connected by means of a flange joint to a gas chamber, a primary air mixing unit located inside the burner, having a space for the injection process and channels for supplying primary air, characterized in that the primary air mixing unit is a tightly fitting rim with rectangular openings located at an equal distance from each other outside the burner around the mixing unit, with a primary air supply regulator fixed on top of the rim, inside which, in a circle at an equal distance from each other, eight blades for mixing the primary air and gas are located, fixed on the inner rim, the blades are attached to the surface of the adjustment rim using a hook-and-eye connection and are connected to an adjustment mechanism consisting of an L-shaped plate,located outside and secured to a fixed support flange, a flame arrester is installed inside the burner, consisting of ribbed plates secured on top of a hollow sleeve mounted on a flame gap regulator, which is a tube located in the center and passing inside through the entire surface of the burner, secured on one side, and at the outlet of the burner connected to a disk distributor with an angle of inclination of 70°, a secondary air regulator is located outside the burner, which is a metal rim located around the burner with projections for fixation, twenty-four blades are located inside at an equal distance from each other, in the upper part of the secondary air regulator there is an opening for the passage of a gas supply pipe to the pilot burner through it, a flame stabilizer is installed at the outlet of the gas supply pipe to the pilot burner.

2. A gas burner according to paragraph 1, characterized in that centralizers are installed in the internal part of the burner and the sleeve, which are guide plates attached to the flame gap regulator tube.

3. A gas burner according to paragraph 1, characterized in that the burner is attached to a fixed support flange using plates installed at the top and bottom of the outer part of the burner, with mounting studs.

4. A gas burner according to paragraph 1, characterized in that the burner is installed in a burner stone made of refractory material.

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