CN1279313C - A kind of circular swirling thick and thin pulverized coal burner - Google Patents

Abstract

The present invention relates to a circular vortex concentration pulverized coal combustor, particularly to a vortex pulverized coal combustion device. A separator plate which divides a primary air pipe into an upper thick pulverized coal pipeline and a lower thin pulverized coal pipeline is arranged in a primary air pulverized coal pipe, a reducing pipe used for evening pulverized coal air flows is arranged in a thick pulverized coal pipeline, a wedge-shaped body is formed between the bottom of the reducing pipe and the separator plate. A fixed swirl blade is arranged in the thin pulverized coal pipeline of the lower part of the primary air pipe, a movable adjustable swirl blade is arranged in a secondary air pipe, and a rotary body with a curved groove on the inner surface is arranged on the wall surface of the front end of the swirl blade of the secondary air pipe. The present invention can effectively lower the NO<x> discharge of pulverized coal fired boilers, and the carbon content of fly ash can not be increased obviously. Meanwhile, when pulverized coal with low volatile matter is combusted, and the problems of low-load ignition and stable combustion and the reduction of the resistance and the abrasion of the primary air pipe are effectively solved. Thereby, the service life of combustion devices is extended, and the performance cost of devices is increased.

Description

A kind of circular swirling thick and thin pulverized coal burner

technical field

The invention relates to a boiler pulverized coal combustion equipment, in particular to a swirling thick and thin pulverized coal burner.

Background technique:

At present, the swirl pulverized coal burners with hedging arrangement on the market mainly include: Beijing Bawei Co., Ltd.'s double air-adjusting pulverized coal burner, and the radial thick and thin pulverized coal burner of Harbin Institute of Technology.

The main structure of the double air-adjusting pulverized coal burner of Beijing Bawei Company is a circular structure. From the inside to the outside, there are primary air duct, inner secondary air duct and outer secondary air duct. There are swirl blades in the inner and outer secondary air ducts; there is no central tube in the primary air duct, and the oil gun is arranged in the secondary air duct and on the upper side of the primary air duct. The advantages of this structure are: there is no pipe in the primary air pipe, which reduces the wear of the pipe by the pulverized coal; the effect of the two-layer swirl blades is easy to generate a large swirl intensity. The disadvantages are: there is no blunt body at the nozzle of the primary air duct, which is not conducive to the formation of a recirculation zone near the wall that is conducive to fire; the swirling effect of the external secondary air makes it difficult to maintain an oxidizing atmosphere near the wall, which is not conducive to preventing high-temperature corrosion and slagging; the primary wind pulverized coal flow has no concentration and light separation, which is not good for the ignition of hard-to-ignite anthracite. Another improved product of the company's burner is the "air-extraction double-adjusting air burner". About 10% of the pulverized coal) is sucked out and sent into the lower part of the furnace to form the concentration separation of pulverized coal. In this structure, only relying on the pressure difference in the pulverized coal pipeline to achieve the suction separation effect of the light pulverized coal flow is not very good, and because the lower temperature of the burner area is low, and the concentration of pulverized coal is low, the ignition point of pulverized coal Higher, the complete combustion of pulverized coal, especially low volatile coal pulverized, is affected.

The structure of the "radial thick-lean pulverized coal burner" used in the prior art is also circular, and from the inside to the outside are the primary air duct, the inner secondary air duct and the outer secondary air duct. There are fixed swirl blades in the inner secondary air duct; the outer secondary air duct has no blades and provides direct air; the primary air duct is equipped with a central tube with an oil gun, and an annular pulverized coal powder between the primary air duct and the central tube A louvered pulverized coal concentrator is arranged in the channel to realize the separation of thick and thin coal pulverized. Its advantage is that the existence of the secondary air outside the direct current makes it easy to form an oxygen-rich oxidative atmosphere on the side of the furnace water wall; the dense coal powder is inside, and the light coal powder is burned on the outside, which is conducive to the ignition and burning of coal powder. The existence of the expansion cone of the nozzle forms a recirculation zone that is conducive to ignition; but in turn, the problem of pulverized coal wear in the central tube is very serious, and the tube is replaced frequently; at the same time, the structure of the pulverized coal concentrator with louvers is prone to occur when the load changes greatly. The phenomenon of powder blocking; and fixing the internal secondary air blade is not conducive to adjusting the angle of the blade with the change of load to produce a suitable swirl intensity.

In view of environmental protection requirements and the characteristics of raw coal reserves, especially with the reduction of raw coal reserves, the quality of coal has become worse and worse. Most of the power industry and industrial coal use low-volatile coal, such as lean coal and anthracite, etc. Their burning feature is that the content of volatile matter is relatively very small (Vdaf<20%), so it is difficult to catch fire, difficult to burn stably, and even more difficult to burn. Along with the emission control standard of _NOx in the world is also getting higher and higher, the development and research of a kind of opposite type swirl pulverized coal burner suitable for low volatile pulverized coal combustion, low _NOx emission and high-efficiency stable combustion has significant actual meaning.

Contents of the invention

Aiming at the deficiencies and defects of the prior art, the object of the present invention is to provide a circular swirling thick-lean pulverized coal burner, which can solve the problems of low-load ignition and stable combustion when burning low-volatile coal pulverized coal, and further reduce NO The generation of _x reduces the resistance and wear of the primary air duct.

Technical scheme of the present invention is as follows:

A circular swirling thick and thin pulverized coal burner, including a primary air pulverized coal pipe with an elbow, a swirling inner secondary air pipe and a direct current outer secondary air pipe arranged concentrically outside the primary air pulverized coal pipe , swirl blades and ignition oil guns are arranged in the inner secondary air pipe, and it is characterized in that: a partition is set at the center of the front end of the elbow of the primary air pulverized coal pipe to divide the primary air pipe into upper and lower thick and light Pulverized coal pipeline, the partition is composed of a straight plate and a slanted plate inclined downward, and small holes are arranged at the rear end of the straight plate; The sleeve is composed of a tapered section, a straight section and a gradually expanded section, and a wedge is formed between the bottom of the sleeve and the partition; in the light coal powder pipeline at the lower part of the primary air duct A fixed swirl vane is provided; a rotating body with a curved groove on the inner surface is arranged on the wall surface of the front end of the swirl vane of the inner secondary air duct.

The technical feature of the present invention is that the swirl blades of the inner secondary air duct adopt movable and adjustable swirl blades.

Another technical feature of the present invention is: the height of the curved channel is 20-50 mm, and the angle between the curved channel and the tangent of the rotating body is 45°.

Another technical feature of the present invention is that: the angles of each air duct flaring are 15-18°; the inner secondary air duct and the DC outer secondary air duct are respectively connected to a separate air box; The ignition oil gun (2) is obliquely arranged directly above the inner secondary air duct at a downward inclination angle of 2° to 5°.

Compared with the prior art, the present invention has the following advantages and outstanding effects: ① the present invention utilizes the joint action of the separation partition in the primary air duct and the concentrated coal powder pipe to form a wedge-shaped body at the outlet of the burner, and establishes It is conducive to the formation of a suitable recirculation zone that can make the pulverized coal airflow ignite in time, and ensures the ignition and combustion stability of pulverized coal, especially low-volatile pulverized coal. ②The burner of the present invention has greater fuel adaptability and load regulation. When the load changes, the air volume required by each can be roughly adjusted through the independent air box structures (primary fan, inner and outer secondary air boxes); secondly, the angle of the adjustable blades of the inner secondary air can be adjusted to change swirl strength; and due to the existence of the fixed rotating curved wedge, the phenomenon of direct current flash of the airflow at low load is avoided, and the problem of low load flame stability is solved, which may lead to flameout in severe cases. ③ Since the burner of the present invention has no center tube at the elbow, the occurrence of wear is reduced, the number of minor repairs of the boiler can be effectively reduced, and the reliability of operation is improved.

To sum up, the present invention adopts the arrangement method of forming a blunt body at the nozzle of the primary air duct without any pipe at the elbow, which avoids the disadvantage of forming a backflow area that is conducive to fire and the central pipe without a central pipe. When the pulverized coal flow at the elbow has the problem of scouring and wear on the central pipe; the separation of the thick and thin coal powder is formed by the joint action of the inertial separation of the elbow and the separation baffle, and the formation of thick coal powder is ignited first, and then the combustion of light coal powder is ignited This method is beneficial to reduce the heat of ignition, reduce the total flame temperature level, and reduce the formation of _NOx . At the same time, the separation structure of the pulverized coal will not increase the resistance in the pulverized coal pipe of the primary air; the internal secondary air pipe can The existence of the wedge-shaped body with curved flow channel at the front end of the moving blade avoids the phenomenon of direct-current flashing of the air flow at the nozzle of the internal secondary air pipe at low load, and solves the problem of flame stability at low load.

Description of drawings

Fig. 1 is a schematic structural view of a circular swirling rich-lean pulverized coal burner provided by the present invention.

Fig. 2 is the right side view of Fig. 1 .

Fig. 3 is a front view of the separation baffle arranged in the primary air pulverized coal pipe.

FIG. 4 is a top view of FIG. 3 .

Fig. 5 is a front view of the reducer arranged in the concentrated pulverized coal pipeline.

Fig. 6 is a front view of a rotating body with a curved channel.

Fig. 7 is a right side view of Fig. 6 .

In the figure: 1. Primary air pulverized coal pipeline; 2. Ignition oil gun; 3. Burner heat insulation baffle; 4. DC external secondary air pipe; 5. Swirling internal secondary air pipe; 6. Primary air coal Powder pipe nozzle; 7. Reducer pipe; 8. Light coal powder pipe; 9. Fixed swirl vane in light coal powder pipeline; Rotating body with curved flow channel in the secondary air duct; 12. Adjusting rod for blades in the inner secondary air duct; 13. Curved flow channel; 14. Separation partition; 15. Elbow of primary air pulverized coal pipe.

Detailed ways

The structure, working principle and best embodiment of the present invention will be further described below in conjunction with the accompanying drawings.

Figures 1 and 2 are schematic diagrams of the overall structure of the circular swirling rich-lean pulverized coal burner provided by the present invention. The burner contains a primary air pulverized coal pipe 1 with an elbow 15, a swirl inner secondary air pipe 5 and a direct current external secondary air pipe 4 that are arranged outside the primary air pulverized coal pipe in turn and are concentrically installed. The inner secondary air pipe 5 is arranged with an adjusting pull rod 12, an adjustable swirl blade 10 and an ignition oil gun 2; a separation partition 14 is arranged in the primary air pulverized coal pipe to divide the primary air pipe into upper and lower thick and thin pulverized coal pipes. The separation partition is composed of a straight plate and a sloping plate inclined downward, and small holes are arranged at the rear end of the straight plate; a reducer for uniform pulverized coal flow is set in the concentrated coal powder pipeline on the upper part of the primary air duct 7. The reducer is composed of a tapered section, a straight section and a divergent section, and a wedge is formed between the bottom of the reducer and the separation partition; A fixed swirl vane 9 is set in the pulverized coal pipeline 8; a circular flare 6 is arranged at the outlet of the pulverized coal pipe; the wall surface of the front end of the swirl vane 10 of the inner secondary air duct is arranged with a curved groove on its inner surface The rotating body 11 of the road 13. The above-mentioned structures are connected by the thermal insulation baffle plate 3 of the burner, and are fixed on the water wall of the boiler.

3 and 4 are the front view and top view of the separation partition 14 arranged in the primary air pulverized coal pipe. The separation partition 14 divides the primary air pulverized coal pipe into the upper and lower thick and thin pulverized coal pipelines, which is composed of a straight plate and a sloping plate inclined downward, and small holes are arranged at the rear end of the straight plate. The diameter of the small hole is 10-20 mm, and its function is to use the pressure of the airflow at the elbow to make part of the air in the pulverized coal airflow that is primarily concentrated by the centrifugal force of the elbow 15 penetrate into the light pulverized coal pipeline. Further increase the pulverized coal concentration in the dense pulverized coal pipeline; the slope of the downward sloping plate is 5 to 10°, so that the light pulverized coal flow under the sloping plate deviates from the center and deflects downward, prolonging the flow of the pulverized coal with the dense pulverized coal. the mixing time.

Fig. 5 is a structural schematic diagram of a reducer 7 for uniform pulverized coal flow arranged in the dense pulverized coal pipeline. The reducer 7 is made up of a tapering section, a straight section and a diverging section. The reducer with an inclination of 3°～10° can evenly concentrate the pulverized-coal air flow, so that the pulverized coal in the concentrated pulverized-coal pipe can be evenly distributed; In favor of stabilizing the ignition point at the outlet of the burner, the gradient of the diverging section is 6°-10°. The reducer 7 forms a wedge-shaped body at the outlet of the burner together with the separation baffle 14. The existence of the separation baffle 14 is conducive to the formation of a stable ignition recirculation zone; The mixing of pulverized coal airflow makes the flame in the furnace longer, and the flame temperature of the furnace section in the burner area decreases, which is beneficial to reduce the formation of _NOx .

A fixed swirl vane 9 is set in the light coal powder pipeline 8 at the bottom of the primary air pulverized coal pipe 1. Through this fixed swirl blade, the light pulverized coal flow is rotated to enhance the disturbance of the light pulverized coal flow, which is beneficial The mixing intensity of the light pulverized coal flow and the ignited thick pulverized coal flow is conducive to the ignition and complete combustion of the light pulverized coal flow.

There are swirl blades 10 arranged in the inner secondary air pipe, which can be adjusted by the adjusting rod 12, and the swirl intensity of the inner secondary air can be correspondingly changed according to the change of boiler load and coal type, thereby changing the size of the recirculation zone. To achieve the purpose of adjusting the ignition point and ignition intensity. A rotating body 11 with a curved groove 13 on the inner surface is arranged on the wall surface of the front end of the swirling blade 10, and the curved groove 13 is 45° to the tangent of the rotating body 11, as shown in Fig. 6 and Fig. 7 . The existence of this rotating body 11 avoids the technical gap formed at the wall surface of the inner secondary air pipe due to the adjustable swirl vanes. Such a gap is easy to cause the air flow required for boiler combustion to fluctuate when the load is low. On the other hand, its curved channel strengthens the swirl strength of the edge airflow, which is beneficial to expand the diameter of the recirculation zone and the flame The diameter is conducive to leveling and reducing the temperature of the flame zone.

The ignition oil gun 2 is obliquely arranged directly above the inner secondary air duct 5 at an inclination angle of 2° to 5°. This arrangement is easy to make the oil gun obliquely extend into the root of the dense coal powder, which is beneficial to burn with less Oil is used for effective ignition, and since there is no coal powder present in this position, there will be no wear problems of the oil gun.

There is no any part in the outer secondary air duct 4 of the present invention, what forms is the direct current outer secondary air, on the one hand its speed is higher 45-60m/s, can improve the dynamic pressure ratio of it and inner secondary air like this, Timely replenish the oxygen required for the incomplete combustion of coke in the later stage; at the same time, such a high speed makes the rigidity of the external secondary air stronger, and the jet flow still has a certain speed in the later stage of combustion, which helps to improve the small-scale air flow in the later stage of combustion. Disturbance, so the higher DC external secondary air can not only improve the large-scale disturbance in the furnace, but also contribute to the small-scale disturbance, which is beneficial to reduce the heat loss of incomplete combustion, and can also significantly reduce fly ash Carbon content. At the same time, the high-speed direct-current external secondary air can cause the combustion mode of air-wrapped powder, so that the vicinity of the furnace water wall is an oxidative atmosphere. In this atmosphere, the ash melting point is relatively high, which is not only beneficial to anti-slagging but also It is beneficial to prevent high-temperature corrosion, and the jet ejection effect of such a high-speed jet can significantly increase the diameter and range of the flame of the airflow. This method increases the overall temperature level of the flame in the burner area, and the temperature peak value is also reduced. , according to the principle of NO _x generation, it can reduce the amount of NO _x generated, and enhance the residence time of particles, so that the amount of NO _x generated by reduction can be increased.

The inner secondary air and the outer secondary air of the present invention are respectively supplied by separate bellows, and the air volume of any one air duct can be adjusted independently without affecting the air volume of another air duct due to the change of the pressure of the same bellows.

In the burner of the present invention, flaring pipes are arranged at the ends of the primary air pipe, the inner secondary air pipe and the outer secondary air pipe, according to the rule that the diameter of the axisymmetric wake flow varies with the 1/3 power of the axial distance Change, design their nozzle expansion angle should be 15-18 °, which is not only conducive to the expansion of the airflow, but also conducive to reducing the resistance loss of the airflow, increasing the length of the flame, and delaying the position of the highest temperature point of the flame.

Claims (6)

1. circular cyclone concentration coal burner, contain a wind coal pipe (1) of being with elbow, be successively set on wind coal pipe outside and interior secondary air channel (5) of eddy flow that install with one heart and the outer secondary air channel (4) of direct current one time, at a said wind coal pipe, the leading section of the outer secondary air channel of secondary air channel and direct current is equipped with enlarging in the eddy flow, be furnished with swirl vane (10) and torch oil gun (2) in the secondary air channel in described (5), it is characterized in that: a separation dividing plate (14) is set in a wind coal pipe airduct is divided into bias pulverized coal pipeline up and down, described separation dividing plate is made of straight plate and downward-sloping swash plate, is furnished with aperture at the rear end part of this straight plate; A reducing pipe (7) that is used for even breeze airflow is set in the thick coal culm pipeline on described top, and this reducing pipe is made up of converging transition, straight section and divergent segment, and the bottom of reducing pipe forms sphenoid with described the separation between the dividing plate; In the thin powdered coal pipeline (8) of the bottom of a described airduct, fixing swirl vane (9) is set; In described, be furnished with the rotary body (11) of inner surface belt curve conduit (13) on the wall of the front end of the swirl vane of secondary air channel (10).

2. according to the described circular cyclone concentration coal burner of claim 1, it is characterized in that: the adjustable swirl vane of swirl vane (10) employing activity of secondary air channel in described.

3. according to the described circular cyclone concentration coal burner of claim 1, it is characterized in that: the height of described curve conduit (13) is 10～20 millimeters, and the tangent line of curve conduit and rotary body is at 45.

4. according to the described circular cyclone concentration coal burner of claim 1, it is characterized in that: the extended corner of described each enlarging is at 15～18 °.

5. according to the described circular cyclone concentration coal burner of the arbitrary claim of claim 1～4, it is characterized in that described in secondary air channel (5) and the outer secondary air channel (4) of direct current be connected with independent bellows respectively.

6. according to the described circular cyclone concentration coal burner of the arbitrary claim of claim 1～4, it is characterized in that: described torch oil gun (2) with 2～5 ° downward inclination angle oblique be arranged in secondary air channel directly over.

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