Annular rich-lean separation combustor for ultra-low load stable combustion

Abstract

The invention relates to the technical field of rich-lean separation combustors, in particular to an annular rich-lean separation combustor for ultra-low load stable combustion, and aims to solve the problems of a flat rich-lean combustor and a vertical rich-lean combustor in practical application at present. The pulverized coal pipeline inlet elbow and the pulverized coal nozzle body are both lined with wear-resistant material coatings, the dense-thin separation device is located in the inlet end of the pulverized coal nozzle body, and the thin-phase primary air rotational flow device is arranged in the middle of the pulverized coal nozzle body and located between the inlet end of a central spray pipe integrated in the middle of the pulverized coal nozzle body and the pulverized coal nozzle body. The pulverized coal combustion nozzle is connected with the outlet end of the pulverized coal nozzle body through a rotating shaft, the inlet end of the center spray pipe is located in the middle of the light-phase primary air rotational flow device, the sealing box is arranged between the pulverized coal combustion nozzle and the pulverized coal nozzle body and used for preventing pulverized coal leakage, and the pump scheme combustor easily enables pulverized coal to be ignited and combusted stably and reduces generation of NOx.

Description

Technical Field

[0001] The invention relates to the technical field of rich-lean separation burners, and in particular to an annular rich-lean separation burner for ultra-low load stable combustion. Background Art

[0002] At present, the most widely used thick-lean burners are horizontal thick-lean burners and vertical thick-lean burners. In practical applications, there are the following problems:

[0003] (1) Poor adaptability to fuel. Most of these burners show good stable combustion ability and low NOx emission performance when burning bituminous coal, but it is difficult to ensure stable combustion ability and low NOx emission performance when burning difficult-to-burn fuels; (2) Unable to adapt to the requirements of deep peak regulation. Due to the development of renewable energy, the peak regulation capacity of power station boilers is required to be higher, and the existing thick-lean burners are difficult to achieve stable combustion without oil injection at 20% load of the boiler, which greatly limits the peak regulation capacity of the boiler; (3) Poor adaptability to the connection structure. After some low stable combustion burners are arranged with a concentration structure, the original swing structure is destroyed, and the boiler adjustment means are reduced; (4) The primary air nozzle structure is unreasonable. Some burners are not only unable to swing, but also only pay attention to the first-level concentration effect of the thick-lean separation device, but the second-level concentration effect of the primary air nozzle and its downstream reflux area is not considered enough, resulting in the burner cannot achieve the ideal stable combustion effect and low NOx emission performance. Summary of the invention

[0004] Purpose of the patent of this invention: In order to solve the problems existing in the current flat thick-lean burners and vertical thick-lean burners in practical applications, the present invention provides an annular thick-lean separation burner for ultra-low load stable combustion.

[0005] The object of the present invention is achieved as follows: an annular thick-lean separation burner for ultra-low load stable combustion, which comprises a pulverized coal pipeline inlet elbow, a pulverized coal nozzle body, a thick-lean separation device, a light phase primary air swirl device, a pulverized coal combustion nozzle and a sealing box;

[0006] The outlet end of the inlet elbow of the pulverized coal pipeline is connected to the inlet end of the pulverized coal nozzle body. The inlet elbow of the pulverized coal pipeline and the pulverized coal nozzle body are lined with a wear-resistant material coating. The thick and thin separation device is located in the inlet end of the pulverized coal nozzle body. The light phase primary air cyclone device is arranged in the middle of the pulverized coal nozzle body, between the inlet end of the central nozzle integrated in the middle of the pulverized coal nozzle body and the pulverized coal nozzle body. The pulverized coal combustion nozzle and the outlet end of the pulverized coal nozzle body are connected by a rotating shaft. The inlet end of the central nozzle is located in the middle of the light phase primary air cyclone device. The sealing box is arranged between the pulverized coal combustion nozzle and the pulverized coal nozzle body to prevent coal powder leakage.

[0007] Furthermore, the thick-thin separation device is a three-stage primary air volume annular thick-thin separation device.

[0008] Furthermore, a coal powder homogenizer structure is provided in the inlet elbow of the powder pipeline.

[0009] Furthermore, the wear-resistant material coating is made of SiC, alumina ceramics, wear-resistant cast steel or bimetallic material.

[0010] Furthermore, the flapping amplitude of the pulverized coal combustion nozzle along the rotating axis is ±20°.

[0011] Beneficial effects:

[0012] The air-coal mixture (primary air) of the pulverized coal airflow at the outlet of the pulverizer under ultra-low load condition (the proportion of air is very high and the pulverized coal concentration is very low) flows through the device of the present invention, and passes through the pulverized coal pipeline inlet elbow with a pulverized coal uniformizer structure and a special shape with an inner lining of wear-resistant material (SiC, alumina ceramic or wear-resistant cast steel, bimetallic material). By utilizing the difference in momentum and inertia of pulverized coal and air at similar flow rates, the primary air-powder mixture evenly enters the pulverized coal nozzle body structure composed of a pulverized coal nozzle body shell with an inner lining of wear-resistant material, a three-stage primary air volume annular thick-thin separation device, and a group of light-phase primary air cyclone devices, and then enters the furnace to participate in combustion.

[0013] The air-powder mixture with a high coal powder concentration is sent into the furnace for combustion through the boiler coal powder burner. The advantages are that it is easy to ignite and burn stably, and the generation of NOx is reduced; the light air-powder mixture in the annular zone is sent into the furnace through the nozzle. Since this airflow still has a high pressure head, it can organize the combustion of the furnace flame, thereby ultimately solving the problems of difficult coal powder ignition, primary air flow brushing the wall, water-cooled wall coking corrosion, overheating, and high NOx emissions when the boiler is running at ultra-low load (20% BMCR and below). BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of an annular rich-lean separation burner used for ultra-low load stable combustion. DETAILED DESCRIPTION

[0015] Specific implementation method 1: An annular thick-lean separation burner for ultra-low load stable combustion, which includes a pulverized coal pipeline inlet elbow 1, a pulverized coal nozzle body 2, a thick-lean separation device 3, a light phase primary air swirl device 4, a pulverized coal combustion nozzle 5 and a sealing box 6;

[0016] The outlet end of the pulverized coal pipeline inlet elbow 1 is connected to the inlet end of the pulverized coal nozzle body 2. The pulverized coal pipeline inlet elbow 1 and the pulverized coal nozzle body 2 are both lined with a wear-resistant material coating. The thick and thin separation device 3 is located in the inlet end of the pulverized coal nozzle body 2. The light phase primary air cyclone device 4 is arranged in the middle of the pulverized coal nozzle body 2, between the inlet end of the central nozzle integrated in the middle of the pulverized coal nozzle body 2 and the pulverized coal nozzle body 2. The pulverized coal combustion nozzle 5 is connected to the outlet end of the pulverized coal nozzle body 2 through a rotating shaft, and the inlet end of the central nozzle is located in the middle of the light phase primary air cyclone device 4. The sealing box 6 is arranged between the pulverized coal combustion nozzle 5 and the pulverized coal nozzle body 2 to prevent coal powder leakage.

[0017] In the present embodiment: a pulverized coal powder distributor structure is provided, a pulverized coal pipe inlet elbow lined with wear-resistant material, a pulverized coal nozzle body shell lined with wear-resistant material, a thick-thin separation device is installed in the pulverized coal nozzle body, a light phase primary air cyclone device is installed on the pulverized coal nozzle body and the thick-thin separation device, the pulverized coal combustion nozzle and the pulverized coal nozzle body are connected together by a rotating shaft, and a sealing box is connected between the pulverized coal combustion nozzle and the pulverized coal nozzle body to prevent pulverized coal leakage.

[0018] Specific implementation method 2: An annular thick-thin separation burner for ultra-low load stable combustion, the thick-thin separation device 3 is a three-stage primary air volume annular thick-thin separation device.

[0019] In this embodiment: the thick-thin separation device is a three-stage primary air volume annular thick-thin separation device, which is installed in the outer shell of the pulverized coal nozzle body with an inner lining of wear-resistant material.

[0020] Other implementations are the same as the first specific implementation.

[0021] Specific implementation method three: A ring-shaped thick-lean separation burner for ultra-low load stable combustion, wherein a pulverized coal pulverizer structure is provided in the pulverized coal pipeline inlet elbow 1.

[0022] In this embodiment: a pulverized coal pipeline inlet elbow is provided with a pulverized coal uniformizer structure, which is arranged in a special proportion and installed at the airflow turning part of the pulverized coal pipeline inlet elbow lined with wear-resistant material.

[0023] Other implementations are the same as the first specific implementation.

[0024] Specific implementation method 4: An annular rich-lean separation burner for ultra-low load stable combustion, wherein the wear-resistant material coating is made of SiC, alumina ceramics, wear-resistant cast steel or bimetallic material.

[0025] In this embodiment: the inlet elbow of the pulverized coal pipeline is a special shape shell with an inner lining of wear-resistant material (SiC, alumina ceramic or wear-resistant cast steel, bimetallic material), which utilizes the momentum and inertia difference of pulverized coal and air at similar flow rates to efficiently and evenly allow the primary air-powder mixture to enter the pulverized coal nozzle body composed of a pulverized coal nozzle body, a thick-light separation device, and a light-phase primary air cyclone device for secondary concentration. The pulverized coal airflow passes through the three-stage annular separation device, the dense-phase pulverized coal airflow enters the dense-phase central tube and is directly sprayed into the furnace, and the light-phase pulverized coal airflow passes through the cyclone device and spirals through the nozzle into the furnace.

[0026] Other implementations are the same as the first specific implementation.

[0027] Specific implementation method five: An annular thick-lean separation burner for ultra-low load stable combustion, the flapping amplitude of the pulverized coal combustion nozzle 5 along the rotation axis is ±20°.

[0028] In this embodiment: the pulverized coal combustion nozzle is installed in the integral large wind box, has a high self-stable combustion ability, has a swing function, and can swing up and down 20 degrees.

[0029] Other implementations are the same as the first specific implementation.

[0030] Working principle:

[0031] Through the specially arranged pulverized coal elbow powder distributor and the specially designed annular thick-thin separation device, the pulverized coal primary air with ultra-high air-to-coal ratio can be "decomposed" by multi-stage separation, so that the primary air pulverized coal concentration in the inner ring center tube is at the optimal ignition concentration, and the outer ring primary air is input into the furnace through a specially designed swirl device to organize combustion, thereby solving the problems of serious imbalance in the primary and secondary air ratio caused by the ultra-high primary air rate when the boiler is operated at ultra-low load, difficulty in ignition of pulverized coal, primary air flow brushing the wall, coking corrosion of the water-cooled wall, overheating, high NOx emissions, etc.

[0032] The purpose of the device of the present invention is to use the device to achieve ultra-low load stable combustion of the boiler, and is suitable for direct current coal-fired boilers with ultra-low stable combustion load requirements.

Claims

1. An annular rich-lean separation burner for ultra-low load stable combustion, characterized in that: It comprises a coal powder pipeline inlet elbow (1), a coal powder nozzle body (2), a thick-light separation device (3), a light-phase primary air cyclone device (4), a coal powder combustion nozzle (5) and a sealing box (6); The outlet end of the coal powder pipeline inlet elbow (1) is connected to the inlet end of the coal powder nozzle body (2); the coal powder pipeline inlet elbow (1) and the coal powder nozzle body (2) are both lined with a wear-resistant material coating; the thick-thin separation device (3) is located in the inlet end of the coal powder nozzle body (2); the thin phase primary air cyclone device (4) is arranged in the middle of the coal powder nozzle body (2), and is located between the inlet end of the central nozzle integrated in the middle of the coal powder nozzle body (2) and the coal powder nozzle body (2); the coal powder combustion nozzle (5) is connected to the outlet end of the coal powder nozzle body (2) through a rotating shaft; the inlet end of the central nozzle is located in the middle of the thin phase primary air cyclone device (4); and the sealing box (6) is arranged between the coal powder combustion nozzle (5) and the coal powder nozzle body (2) to prevent coal powder leakage.

2. The annular rich-lean separation burner for ultra-low load stable combustion according to claim 1, characterized in that: The thick-thin separation device (3) is a three-stage primary air volume annular thick-thin separation device.

3. The annular rich-lean separation burner for ultra-low load stable combustion according to claim 1, characterized in that: A coal powder homogenizer structure is provided in the powder pipeline inlet elbow (1).

4. The annular rich-lean separation burner for ultra-low load stable combustion according to claim 1, characterized in that: The wear-resistant material coating is made of SiC, alumina ceramics, wear-resistant cast steel or bimetallic material.

5. The annular rich-lean separation burner for ultra-low load stable combustion according to claim 1, characterized in that: The flapping amplitude of the pulverized coal combustion nozzle (5) along the rotating shaft is ±20°.

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