阅读说明：本技术 一种富氧煤粉燃烧器及其基于抽吸引射的燃烧方法 (Oxygen-enriched pulverized coal burner and combustion method based on suction injection ) 是由 冯乐乐 吴玉新 黄文仕 张海 吕俊复 于 2019-09-20 设计创作，主要内容包括：本发明公开了一种富氧煤粉燃烧器及其基于抽吸引射的燃烧方法。燃烧器包括一次风管道、调整风管道、预燃室和喷口。一次风管道和调整风管道呈偏心式设置在预燃室的入口端。预燃室设置在喷口的入口端,且与喷口同轴设置。喷口入口端还设置有纯氧管道,设置在预燃室的外侧。纯氧管道外套筒式设有循环烟气管道。使一次空气携带着煤粉通过一次风管道通入预燃室,形成偏心射流和局部卷吸。调整风管道通入的调整空气,使得煤粉在预燃室内部分热解和燃烧,形成混合燃料风进入喷口。高速纯氧在循环烟气裹夹下,使混合燃料风燃烧推延,又形成炉内烟气卷吸降低火焰温度峰值。本发明具有促进煤粉燃烧的同时又保障受热面安全等优点。(The invention discloses an oxygen-enriched pulverized coal burner and a combustion method based on suction injection. The combustor comprises a primary air pipeline, an adjusting air pipeline, a precombustion chamber and a nozzle. The primary air pipeline and the adjusting air pipeline are eccentrically arranged at the inlet end of the precombustion chamber. The precombustion chamber is arranged at the inlet end of the nozzle and is coaxial with the nozzle. The nozzle inlet end is also provided with a pure oxygen pipeline which is arranged outside the precombustion chamber. The pure oxygen pipeline is sleeved with a circulating flue gas pipeline. The primary air is led into the precombustion chamber through the primary air pipeline with the pulverized coal to form eccentric jet flow and local entrainment. Adjusting air introduced into the air pipeline to ensure that the pulverized coal is partially pyrolyzed and combusted in the precombustion chamber to form mixed fuel air entering the nozzle. The high-speed pure oxygen is wrapped and clamped by the circulating flue gas, so that the mixed fuel air is combusted and delayed, and flue gas entrainment in the furnace is formed to reduce the flame temperature peak value. The invention has the advantages of promoting the combustion of the pulverized coal and simultaneously ensuring the safety of the heating surface, and the like.)

1. An oxygen-rich pulverized coal burner, which can be arranged in a furnace (8), characterized in that the burner comprises a primary air duct (1), an adjusting air duct (2), a precombustion chamber (3) and a nozzle (6); the nozzle (6) is arranged in the hearth (8) as the outlet end of the burner; the primary air pipeline (1) and the adjusting air pipeline (2) are eccentrically arranged at the inlet end of the precombustion chamber (3); the pre-combustion chamber (3) is arranged at the inlet end of the nozzle (6) and is coaxially arranged with the nozzle (6); the inlet end of the nozzle (6) is also provided with a pure oxygen pipeline (4), and the pure oxygen pipeline (4) is arranged on the outer side of the precombustion chamber (3).

2. An oxygen-enriched pulverized coal burner as claimed in claim 1, characterized in that said pure oxygen ducts (4) are provided in two, symmetrically at the inlet end of said nozzle (6).

3. An oxygen-enriched pulverized coal burner as claimed in claim 1 or 2, characterized in that the burner further comprises a circulating flue gas duct (5), the circulating flue gas duct (5) being telescopically arranged at the periphery of the pure oxygen duct (4) concentrically with the pure oxygen duct (4).

4. An oxygen-enriched pulverized coal burner as claimed in claim 3, characterized in that the cross-sectional area of the circulating flue gas duct (5) is 2-5 times the cross-sectional area of the pure oxygen duct (4).

5. An oxygen-enriched pulverized coal burner as claimed in claim 1, characterized in that the cross-sectional area of the jet (6) is 10-20 times the cross-sectional area of the prechamber (3); the sectional area of the precombustion chamber (3) is 2-10 times of the sectional area of the adjusting air duct (2).

6. An oxygen-enriched pulverized coal burner as claimed in claim 3, characterized in that the cross-sectional area of the prechamber (3) is 10-40 times the cross-sectional area of the circulating flue gas duct (5).

7. An oxygen-enriched pulverized coal burner as claimed in claim 6, characterized in that the distance from the central axis of the circulating flue gas duct (5) to the central axis of the prechamber (3) is 2-6 times the radius of the prechamber (3).

8. An oxygen-rich pulverized coal burner suction injection-based combustion method using the oxygen-rich pulverized coal burner as claimed in claim 1, characterized in that the method comprises:

the primary air with the pulverized coal is led into the precombustion chamber (3) through the primary air pipeline (1), and the eccentric jet flow of the primary air in the precombustion chamber is used for forming local entrainment in the precombustion chamber (3) and an outlet of the precombustion chamber, so that the pulverized coal is heated and ignited;

a proper amount of air is introduced into the pre-combustion chamber (3) through the adjusting air pipeline (2) to be used as adjusting air, so that the pulverized coal is partially pyrolyzed and combusted in the pre-combustion chamber (3) to form mixed fuel air to enter a nozzle (6);

pure oxygen is injected into the nozzle (6) from the pure oxygen pipeline (4) at a speed of 100-200 m/s, and the pure oxygen is used as secondary air to further combust mixed fuel air and form smoke entrainment in the furnace to reduce the flame temperature peak value.

9. The pulverized coal burner combustion method based on suction injection as claimed in claim 8, characterized in that the burner further comprises a circulating flue gas duct (5), the circulating flue gas duct (5) is telescopically arranged at the periphery of the pure oxygen duct (4) and is arranged in a concentric circle with the pure oxygen duct (4); the method further comprises the following steps:

the pure oxygen is sprayed into the nozzle (6) from the pure oxygen pipeline (4) at a speed of 100-200 m/s, and meanwhile, the circulating flue gas is sprayed in through the circulating flue gas pipeline (5) to clamp and dilute the pure oxygen, so that the secondary air formed by the pure oxygen and the circulating flue gas is used for delaying the combustion of the mixed fuel air, and the flue gas entrainment in the furnace is formed to reduce the flame temperature peak value.

Technical Field

The invention relates to an oxygen-enriched pulverized coal burner and a combustion method based on suction injection thereof, belonging to the technical field of combustion.

Background

Greenhouse gas emissions are a hot spot of widespread concern in today's international society. The combination of oxygen-enriched combustion technology and carbon dioxide capture and sealing technology can effectively control the carbon dioxide emission of coal-fired power stations. The oxyfuel combustion technology is a combustion mode in which pure oxygen obtained from an air separation unit is mixed with recycled flue gas and then used as an oxidant to replace air. The oxygen-enriched combustion technology enriches carbon dioxide in the tail gas, and is convenient for subsequent separation and capture. However, due to the difference in physical and chemical properties between carbon dioxide and nitrogen, problems such as delay of ignition, low flame temperature, etc. occur in oxyfuel combustion. On the other hand, as the circulating flue gas needs to utilize an additional fan, the plant power consumption rate is increased, and the overall efficiency of the power plant is reduced. Therefore, the economic and environment-friendly technical route is as follows: the method has the advantages that the amount of recycled flue gas is reduced, the oxygen concentration at the inlet is increased, the flame temperature is controlled not to be too high, and the safety of a heating surface is guaranteed. Under the background, the development of a novel oxygen-enriched pulverized coal burner is an urgent need of coal-fired power generation enterprises.

The existing technologies cannot solve the above problems at the same time. For example, the existing oxygen-enriched coal-fired boiler generally adopts a method of increasing the inlet oxygen concentration from 21% to 30%, and the problems of delayed ignition, low flame temperature, high energy consumption of a flue gas circulating fan and the like are solved. However, the ignition time is still longer than that of an air coal-fired boiler, the energy consumption of the circulating fan is still large, and the efficiency of a power plant is still low. If the inlet oxygen concentration is further increased, although the problems can be solved, the peak heat flow density in the furnace is too high, the safety of the heating surface is seriously threatened, and the production requirement cannot be met.

Aiming at the engineering background, the oxygen-enriched pulverized coal combustion technology which can be suitable for the working condition of high oxygen concentration is researched and developed, so that the technical problem which needs to be solved urgently is solved, the ignition characteristic and flame temperature of oxygen-enriched combustion can be ensured successfully, and the combustion stability and the heat exchange in the furnace are facilitated; meanwhile, the energy consumption of the flue gas circulating fan can be reduced, the overall efficiency of a power plant is improved, and good economic benefits are obtained.

Disclosure of Invention

The invention aims to provide an oxygen-enriched pulverized coal burner and a combustion method based on suction injection, on one hand, pulverized coal jet flow is promoted to be heated through entrainment of eccentric primary air in a precombustion chamber, so that the ignition distance is shortened; on the other hand, the temperature in the furnace is more uniform through the entrainment of the high-speed secondary air, and the peak heat flux density can not be too high even under the condition of higher oxygen concentration.

The invention is realized by the following technical scheme:

an oxygen-enriched pulverized coal burner comprises a primary air pipeline, an adjusting air pipeline, a precombustion chamber and a nozzle; the nozzle is used as the outlet end of the burner and is arranged in the hearth; the primary air pipeline and the adjusting air pipeline are eccentrically arranged at the inlet end of the precombustion chamber; the pre-combustion chamber is arranged at the inlet end of the nozzle and is coaxially arranged with the nozzle; the nozzle inlet end is further provided with a pure oxygen pipeline, and the pure oxygen pipeline is arranged on the outer side of the pre-combustion chamber.

In the technical scheme, the two pure oxygen pipelines are symmetrically arranged at the nozzle inlet end.

In the technical scheme, the combustor further comprises a circulating flue gas pipeline, wherein the circulating flue gas pipeline is arranged on the periphery of the pure oxygen pipeline in a sleeve mode and is arranged in a concentric circle with the pure oxygen pipeline.

In the technical scheme, the sectional area of the circulating flue gas pipeline is 2-5 times of that of the pure oxygen pipeline.

In the technical scheme, the cross section area of the nozzle is 10-20 times of that of the precombustion chamber; the cross section of the precombustion chamber is 2-10 times of the cross section of the adjusting air duct.

In the technical scheme, the sectional area of the precombustion chamber is 10-40 times of that of the circulating flue gas pipeline.

In the technical scheme, the distance from the central axis of the circulating flue gas pipeline to the central axis of the precombustion chamber is 2-6 times of the radius of the precombustion chamber.

An oxygen-enriched pulverized coal burner combustion method based on suction injection comprises the following steps:

the primary air is led into the pre-combustion chamber through the primary air pipeline with the pulverized coal, and partial entrainment is formed in the pre-combustion chamber and an outlet thereof by means of the eccentric jet flow of the primary air in the pre-combustion chamber, so that the pulverized coal is heated and ignited;

introducing a proper amount of air into the pre-combustion chamber through an adjusting air pipeline to serve as adjusting air, so that the pulverized coal is partially pyrolyzed and combusted in the pre-combustion chamber to form mixed fuel air to enter a nozzle;

the pure oxygen is sprayed into the nozzle from the pure oxygen pipeline at the speed of 100-200 m/s, and the pure oxygen is used as secondary air to further combust mixed fuel air and form smoke entrainment in the furnace to reduce the flame temperature peak value.

In the above technical solution, the method further includes:

the pure oxygen is sprayed into the nozzle from the pure oxygen pipeline at a speed of 100-200 m/s, and meanwhile, the circulating flue gas is sprayed into the nozzle through the circulating flue gas pipeline to clamp and dilute the pure oxygen, so that the secondary air formed by the pure oxygen and the circulating flue gas is used for delaying the combustion of the mixed fuel air, and the flue gas entrainment in the furnace is formed to reduce the flame temperature peak value.

The invention has the following advantages and beneficial effects: the entrainment of the biased primary air in the precombustion chamber can promote the heating of the pulverized coal jet by the high-temperature flue gas and shorten the ignition distance. Secondary air formed by circulating flue gas and pure oxygen is sprayed into the upper side and the lower side of the precombustion chamber at a high speed, so that a large amount of flue gas in the furnace is sucked, the peak heat flow density cannot be too high even under the working condition of high oxygen concentration, and the safety of a heating surface is guaranteed.

Drawings

FIG. 1 is a schematic view of an oxygen-enriched pulverized coal burner according to the present invention.

In the figure: 1-primary air duct; 2-adjusting an air duct; 3-a precombustion chamber; 4-a pure oxygen pipeline; 5-circulating flue gas pipeline; 6-nozzle; 7-refractory material; 8-hearth.

Detailed Description

The following describes the embodiments and operation of the present invention with reference to the accompanying drawings.

The terms of orientation such as up, down, left, right, front, and rear in the present specification are established based on the positional relationship shown in the drawings. The corresponding positional relationship may also vary depending on the drawings, and therefore, should not be construed as limiting the scope of protection.

As shown in FIG. 1, an oxygen-enriched pulverized coal burner includes a primary air duct 1, a pilot air duct 2, a precombustion chamber 3, and a nozzle 6. The outlet end of the burner of the nozzle 6 is arranged in the hearth 8. The primary air duct 1 and the adjusting air duct 2 are eccentrically arranged at the inlet end of the precombustion chamber 3. The precombustion chamber 3 is arranged at the inlet end of the nozzle 6 and is coaxially arranged with the nozzle 6, and the two are connected through a flange or welded. The sectional area of the nozzle 6 is 10-20 times of that of the precombustion chamber 3. The sectional area of the precombustion chamber 3 is 2-10 times of the sectional area of the adjusting air duct 2.

The inlet end of the nozzle 6 is also provided with a pure oxygen pipeline 4, and the pure oxygen pipeline 4 is arranged outside the precombustion chamber 3. As an optimized technical scheme, two pure oxygen pipelines 4 are arranged and symmetrically arranged at the inlet end of the nozzle 6.

The periphery of the pure oxygen pipeline 4 is also provided with a circulating flue gas pipeline 5, and the circulating flue gas pipeline 5 is arranged in a sleeve mode and is arranged in a concentric circle with the pure oxygen pipeline 4. The sectional area of the circulating flue gas pipeline 5 is 2-5 times of that of the pure oxygen pipeline 4.

The sectional area of the precombustion chamber 3 is 10-40 times of that of the circulating flue gas pipeline 5. The distance between the central axis of the circulating flue gas pipeline 5 and the central axis of the precombustion chamber 3 is 2-6 times of the radius of the precombustion chamber 3.

The primary air is led into the precombustion chamber 3 through the primary air pipeline 1 with the pulverized coal, and due to the eccentric arrangement of the primary air pipeline 1, the primary air is in an eccentric jet flow in the precombustion chamber, so that local entrainment is formed in the precombustion chamber 3 and an outlet of the precombustion chamber, and the pulverized coal is promoted to be heated and fired.

And a proper amount of air is introduced into the precombustion chamber 3 through the adjusting air pipeline 2 to be used as adjusting air, so that the pulverized coal is partially pyrolyzed and combusted in the precombustion chamber 3. The combustion of the pulverized coal is in the form of a micro-fire star instead of a distinct flame. So that both a good ignition quality is ensured and an excessively high combustion temperature in the prechamber 3 is avoided. The partial pyrolyzed and combusted pulverized coal, primary air, adjusting air, pyrolysis gas and combustion flue gas form mixed fuel air to enter the nozzle 6.

The pure oxygen is sprayed into the nozzle 6 from the pure oxygen pipeline 4 at a speed of 100-200 m/s, and meanwhile, the circulating flue gas is sprayed into the nozzle through the circulating flue gas pipeline 5 to clamp and dilute the pure oxygen. At the moment, the circulating flue gas wraps pure oxygen, so that the mixing of oxygen of secondary air and mixed fuel air is delayed; the high-speed jet flow of the secondary air causes strong entrainment of flue gas in the furnace, and controls the peak value of flame temperature. Therefore, even under the working condition of high oxygen concentration, the combustion intensity can be effectively controlled, and the safety of the heating surface is guaranteed.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.