CN110594728A - Oxygen-enriched pulverized coal burner and combustion method based on suction injection - Google Patents

Abstract

The invention discloses an oxygen-enriched pulverized coal burner and a combustion method based on suction injection. The burner includes a primary air duct, an adjustment air duct, a pre-combustion chamber and a nozzle. The primary air duct and the adjusting air duct are eccentrically arranged at the inlet end of the pre-combustion chamber. The pre-combustion chamber is arranged at the inlet end of the nozzle and coaxially arranged with the nozzle. The inlet end of the nozzle is also provided with a pure oxygen pipeline, which is arranged outside the pre-combustion chamber. The outer sleeve type of the pure oxygen pipeline is equipped with a circulating flue gas pipeline. Make the primary air carry coal powder into the pre-combustion chamber through the primary air duct to form eccentric jet flow and local entrainment. The adjusted air fed into the air duct is adjusted so that the pulverized coal is partially pyrolyzed and burned in the pre-combustion chamber to form mixed fuel air and enter the nozzle. The high-speed pure oxygen is wrapped in the circulating flue gas, so that the combustion of the mixed fuel air is delayed, and the flue gas entrainment in the furnace is formed to reduce the peak temperature of the flame. The invention has the advantages of promoting the combustion of pulverized coal and ensuring the safety of the heating surface.

Description

An oxygen-enriched pulverized coal burner and its combustion method based on suction injection

technical field

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

Background technique

Greenhouse gas emission is a hot issue that is widely concerned by the international community today. The combination of oxyfuel combustion technology and carbon dioxide capture and storage technology can effectively control carbon dioxide emissions from coal-fired power plants. Oxygen-enriched combustion technology refers to a combustion method in which pure oxygen obtained from an air separation unit is mixed with recirculated flue gas, and then used as an oxidant instead of air. The oxygen-enriched combustion technology enriches the carbon dioxide in the tail gas, which 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 delayed ignition and low flame temperature may occur in oxyfuel combustion. On the other hand, due to the need to use additional fans for circulating flue gas, the power consumption rate of the plant is increased and the overall efficiency of the power plant is reduced. Therefore, the more economical and environmentally friendly technical route is: while reducing the amount of recirculated flue gas, increase the inlet oxygen concentration, and at the same time control the flame temperature from being too high to ensure the safety of the heating surface. In this context, the development of a new type of oxygen-enriched pulverized coal burner is an urgent need for coal-fired power generation enterprises.

Currently existing technologies cannot simultaneously solve the above problems. For example, the existing oxygen-enriched coal-fired boilers usually adopt the method of increasing the inlet oxygen concentration from 21% to 30% to alleviate the problems of ignition delay, low flame temperature, and high energy consumption of flue gas circulation fans. However, the ignition time at this time is still longer than that of air-fired coal-fired boilers, the energy consumption of circulating fans is still large, and the efficiency of power plants is still low. If the inlet oxygen concentration is further increased, although the above problems can be solved, the peak heat flux density in the furnace will be too large, which seriously threatens the safety of the heating surface and cannot meet the needs of production.

In view of this engineering background, the research and development of oxygen-enriched pulverized coal combustion technology suitable for high oxygen concentration conditions has become an urgent technical problem to be solved. Its successful development can ensure the ignition characteristics and flame temperature of oxygen-enriched combustion, which is beneficial to Combustion stability and heat exchange in the furnace; at the same time, it can reduce the energy consumption of the flue gas circulation fan, which is conducive to improving the overall efficiency of the power plant and achieving good economic benefits.

Contents of the invention

The present invention aims to provide an oxygen-enriched pulverized coal burner and its combustion method based on suction injection. On the one hand, the entrainment of the eccentric primary air in the pre-combustion chamber promotes the heating of the pulverized coal jet, so that the ignition distance is shortened; On the one hand, through the entrainment of high-speed secondary air, the temperature in the furnace is more uniform, and the peak heat flux density will not be too high even at a relatively high oxygen concentration.

The present invention is realized through the following technical solutions:

An oxygen-enriched pulverized coal burner, comprising a primary air duct, an adjustment air duct, a pre-combustion chamber and a spout; the spout is arranged in the furnace as the outlet end of the burner; The pipeline is arranged eccentrically at the inlet end of the pre-chamber; the pre-chamber is arranged at the inlet end of the nozzle and coaxially arranged with the nozzle; the inlet end of the nozzle is also provided with a pure oxygen pipeline, The pure oxygen pipeline is arranged outside the pre-combustion chamber.

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

In the above technical solution, the burner further includes a flue gas circulation pipe, the flue gas circulation pipe is sleeved on the outer periphery of the pure oxygen pipe, and is concentrically arranged with the pure oxygen pipe.

In the above technical solution, the cross-sectional area of the circulating flue gas pipeline is 2 to 5 times the cross-sectional area of the pure oxygen pipeline.

In the above technical solution, the cross-sectional area of the nozzle is 10-20 times the cross-sectional area of the pre-chamber; the cross-sectional area of the pre-chamber is 2-10 times the cross-sectional area of the air conditioning duct.

In the above technical solution, the cross-sectional area of the pre-combustion chamber is 10 to 40 times the cross-sectional area of the circulating flue gas pipeline.

In the above technical solution, the distance from the central axis of the circulating flue gas duct to the central axis of the pre-chamber is 2 to 6 times the radius of the pre-chamber.

A combustion method based on suction injection of an oxygen-enriched pulverized coal burner, comprising:

Make the primary air carry the pulverized coal into the pre-combustion chamber through the primary air duct, and use the eccentric jet flow of the primary air in the pre-combustion chamber to make the pre-combustion chamber and its outlet form local entrainment to promote the heating and ignition of the coal powder;

Through the adjustment of the air duct, an appropriate amount of air is introduced into the pre-combustion chamber as the adjustment air, so that the pulverized coal is partially pyrolyzed and burned in the pre-combustion chamber, and the mixed fuel air enters the nozzle;

The pure oxygen is injected from the pure oxygen pipeline into the nozzle at a speed of 100-200m/s, which not only serves as the secondary air to further burn the mixed fuel air, but also forms the flue gas entrainment in the furnace to reduce the peak temperature of the flame.

In the above technical solution, the method also includes:

The pure oxygen is sprayed from the pure oxygen pipeline into the nozzle at a speed of 100-200m/s, and the circulating flue gas is injected through the circulating flue gas pipeline to enclose and dilute the pure oxygen, so that the pure oxygen and the circulating flue gas are formed The secondary wind delays the combustion of the mixed fuel air, and forms the smoke entrainment in the furnace to reduce the peak temperature of the flame.

The invention has the following advantages and beneficial effects: the entrainment effect of the biased primary air in the pre-combustion chamber can promote the heating of the pulverized coal jet by the high-temperature flue gas, and shorten the ignition distance. The secondary air composed of circulating flue gas and pure oxygen is sprayed into the upper and lower sides of the pre-combustion chamber at high speed, resulting in a large amount of flue gas entrainment in the furnace, which can ensure that the peak heat flux density will not be too high even under high oxygen concentration conditions , to ensure the safety of the heating surface.

Description of drawings

Fig. 1 is a schematic diagram of an oxygen-enriched pulverized coal burner involved in the present invention.

In the figure: 1—primary air duct; 2—adjusting air duct; 3—precombustion chamber; 4—pure oxygen pipe; 5—circulating flue gas pipe; 6—spout; 7—refractory material; 8—furnace.

Detailed ways

The specific embodiment of the present invention and working process will be further described below in conjunction with accompanying drawing.

The orientation terms such as up, down, left, right, front and rear in this application document are established based on the positional relationship shown in the drawings. If the drawings are different, the corresponding positional relationship may also change accordingly, so this should not be understood as limiting the scope of protection.

As shown in FIG. 1 , an oxygen-enriched pulverized coal burner includes a primary air duct 1 , an adjustment air duct 2 , a pre-combustion chamber 3 and a nozzle 6 . The outlet end of the nozzle 6 burner is arranged in the furnace 8 . The primary air duct 1 and the adjusting air duct 2 are eccentrically arranged at the inlet end of the pre-chamber 3 . The pre-chamber 3 is arranged at the inlet end of the nozzle 6, and is arranged coaxially with the nozzle 6, and the two are connected by flanges or welded. The sectional area of the nozzle 6 is 10 to 20 times of the sectional area of the pre-chamber 3 . The sectional area of the pre-combustion chamber 3 is 2 to 10 times the sectional area of the air duct 2 for adjustment.

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 pre-combustion chamber 3 . As an optimized technical solution, two pure oxygen pipelines 4 are arranged symmetrically at the inlet end of the nozzle 6 .

The outer periphery of the pure oxygen pipeline 4 is also provided with a circulating flue gas pipeline 5 , which is arranged in a sleeve type and arranged concentrically with the pure oxygen pipeline 4 . The cross-sectional area of the circulating flue gas pipe 5 is 2 to 5 times that of the pure oxygen pipe 4 .

The cross-sectional area of the pre-combustion chamber 3 is 10 to 40 times the cross-sectional area of the circulating flue gas pipeline 5 . The distance from the central axis of the circulating flue gas pipe 5 to the central axis of the pre-combustion chamber 3 is 2 to 6 times the radius of the pre-combustion chamber 3 .

Make the primary air carry the pulverized coal into the pre-combustion chamber 3 through the primary air pipe 1. Due to the eccentric arrangement of the primary air pipe 1, the primary air is an eccentric jet in the pre-combustion chamber, so that the pre-combustion chamber 3 and its outlet form a local volume. Inhalation, to promote heat and fire of coal powder.

An appropriate amount of air is introduced into the pre-combustion chamber 3 through the air duct 2 as the adjustment air, so that the pulverized coal is partially pyrolyzed and burned in the pre-combustion chamber 3 . At this time, the combustion of pulverized coal is like a slightly ignited spark, rather than an obvious flame. Therefore, good ignition performance can be ensured, and excessive combustion temperature in the pre-combustion chamber 3 can be avoided. Partially pyrolyzed and burned coal powder, primary air, adjusted air, pyrolysis gas, and combustion flue gas form a mixed fuel air and enter the nozzle 6.

The pure oxygen is sprayed from the pure oxygen pipeline 4 into the nozzle 6 at a speed of 100-200m/s, and the circulating flue gas is injected through the circulating flue gas pipeline 5 to enclose and dilute the pure oxygen. At this time, the circulating flue gas is wrapped with pure oxygen, which delays the mixing of the secondary air oxygen and the mixed fuel air; the high-speed jet of the secondary air causes strong smoke entrainment in the furnace and controls the peak value of the flame temperature. Therefore, even under the condition of high oxygen concentration, the combustion intensity can be effectively controlled to ensure the safety of the heating surface.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (9)

1. an oxygen-enriched pulverized coal burner, said burner can be arranged in the furnace (8), it is characterized in that said burner comprises primary air duct (1), adjustment air duct (2), pre-combustion chamber (3) and the spout (6); the spout (6) is arranged in the furnace (8) as the outlet end of the burner; the primary air duct (1) and the adjustment air duct (2) are eccentric The formula is arranged at the inlet port of the pre-chamber (3); the pre-chamber (3) is arranged at the inlet port of the nozzle (6), and is arranged coaxially with the nozzle (6); the nozzle (6) A pure oxygen pipeline (4) is also provided at the inlet end, and the pure oxygen pipeline (4) is arranged outside the pre-combustion chamber (3). 2 . The oxygen-enriched pulverized coal burner according to claim 1 , characterized in that, two pure oxygen pipelines ( 4 ) are arranged symmetrically at the inlet end of the nozzle ( 6 ). 3. A kind of oxygen-enriched pulverized coal burner according to claim 1 or 2, characterized in that, the burner also includes a circulating flue gas pipeline (5), and the circulating flue gas pipeline (5) is in the form of a sleeve The formula is arranged on the outer circumference of the pure oxygen pipeline (4), and is arranged concentrically with the pure oxygen pipeline (4). 4 . The oxygen-enriched pulverized coal burner according to claim 3 , characterized in that, the cross-sectional area of the circulating flue gas pipeline ( 5 ) is 2 to 5 times the cross-sectional area of the pure oxygen pipeline ( 4 ). 5. The oxygen-enriched pulverized coal burner according to claim 1, characterized in that, the cross-sectional area of the nozzle (6) is 10 to 20 times the cross-sectional area of the pre-combustion chamber (3); The cross-sectional area of the combustion chamber (3) is 2 to 10 times the cross-sectional area of the air conditioning duct (2). 6. The oxygen-enriched pulverized coal burner according to claim 3, characterized in that the cross-sectional area of the pre-combustion chamber (3) is 10 to 40 times the cross-sectional area of the circulating flue gas pipeline (5). 7. A kind of oxygen-enriched pulverized coal burner according to claim 6, characterized in that, the distance from the central axis of the circulating flue gas pipeline (5) to the central axis of the pre-combustion chamber (3) is the 2 to 6 times the radius of the combustion chamber (3). 8. an oxygen-enriched pulverized coal burner is based on the combustion method of suction injection, and it uses a kind of oxygen-enriched pulverized coal burner as claimed in claim 1, is characterized in that, described method comprises: Make the primary air carry coal powder into the pre-combustion chamber (3) through the primary air duct (1), and use the eccentric jet flow of the primary air in the pre-combustion chamber to make the pre-combustion chamber (3) and its outlet form local entrainment, Promote heating and ignition of pulverized coal; Through the adjustment air duct (2), an appropriate amount of air is introduced into the pre-combustion chamber (3) as the adjustment air, so that the coal powder is partially pyrolyzed and burned in the pre-combustion chamber (3), and the mixed fuel air is formed and enters the nozzle (6); The pure oxygen is sprayed from the pure oxygen pipeline (4) into the nozzle (6) at a speed of 100-200m/s, which not only serves as secondary air to further burn the mixed fuel air, but also forms smoke entrainment in the furnace to reduce the peak temperature of the flame. 9. oxygen-enriched pulverized coal burner according to claim 8 is based on the combustion method of suction injection, is characterized in that, described burner also comprises circulation flue gas duct (5), and described circulation flue gas duct (5) It is arranged in a sleeve type on the outer periphery of the pure oxygen pipeline (4), and is concentrically arranged with the pure oxygen pipeline (4); the method also includes: The pure oxygen is sprayed from the pure oxygen pipeline (4) into the nozzle (6) at a speed of 100-200m/s, and the circulating flue gas is sprayed through the circulating flue gas pipeline (5) to enclose and dilute the pure oxygen. It not only makes the secondary air formed by pure oxygen and circulating flue gas delay the combustion of the mixed fuel air, but also forms the flue gas entrainment in the furnace to reduce the peak temperature of the flame.