Cold and hot flue gas mixed combustion system for high-speed rail high-alkali coal boiler

Abstract

A hot and cold flue gas mixed combustion system for a high-speed iron high-alkali coal boiler comprises a hot primary air duct, a hot flue gas blower, a hot flue gas duct, a cold flue gas duct and a cold flue gas blower; the hot flue gas extraction port is arranged on the turning chamber of the boiler, the hot flue gas blower is arranged on the hot flue gas duct, the two ends of the hot flue gas duct are respectively connected to the hot primary air duct and the hot flue gas extraction port, the cold flue gas extraction port is arranged on the cold flue, the cold flue gas blower is arranged on the cold flue gas duct, the two ends of the cold flue gas duct are respectively connected to the hot primary air duct and the cold flue gas extraction port, the inlet of the coal mill is connected to the hot primary air duct, and its outlet is connected to the burner through a pulverized coal duct, and the burner is arranged on the boiler. The present invention can effectively reduce the oxygen concentration in the primary air pulverized coal airflow, delay the ignition of the pulverized coal, prevent slagging in the area near the burner, and reduce the possibility of coking, contamination and dust accumulation in the boiler.

Description

Technical Field

[0001] The present invention belongs to the field of boiler combustion, and in particular relates to a cold and hot smoke mixed combustion system for a high-iron and high-alkali coal boiler. Background Art

[0002] my country's Xinjiang region has proven to have abundant coal resources high in alkali metals, some of which contain high levels of iron. High levels of alkali metals like sodium and potassium lead to severe slagging and fouling of heating surfaces in boilers during combustion. High iron content in coal can significantly accelerate these problems.

[0003] Domestic power plant boilers equipped with medium-speed mills or earlier steel ball mill pulverizing systems experience severe slagging, fouling, and ash accumulation when burning this type of coal, compared to high-alkali coal. This severely impacts the safe and stable operation of power plant boilers. To operate this high-iron, high-alkali coal, domestic power plants can only mitigate the severe slagging, fouling, and ash accumulation caused by this high-iron, high-alkali coal by reducing load or operating with a small amount of blending. Under these operating conditions, the utilization rate of this high-iron, high-alkali coal is very low, severely impacting the utilization rate of coal-fired power generation and the development of the coal-fired power industry. Summary of the Invention

[0004] In order to overcome the deficiencies of the prior art, the present invention provides a cold and hot flue gas mixed combustion system for a high iron and high alkali coal boiler.

[0005] The hot and cold flue gas mixed combustion system for high-speed rail high-alkali coal boiler includes a hot primary air duct, a hot flue gas fan, a hot flue gas duct, a cold flue gas duct and a cold flue gas fan; the hot smoke extraction port is arranged on the turning chamber of the boiler, the hot flue gas fan is arranged on the hot flue gas duct, the two ends of the hot flue gas duct are respectively connected to the hot primary air duct and the hot smoke extraction port, the cold smoke extraction port is arranged on the cold flue, the cold flue gas fan is arranged on the cold flue gas duct, the two ends of the cold flue gas duct are respectively connected to the hot primary air duct and the cold smoke extraction port, the inlet of the pulverizer is connected to the hot primary air duct, and its outlet is connected to the burner through the pulverized coal duct, and the burner is arranged on the boiler.

[0006] The beneficial effects of the present invention compared to the prior art are:

[0007] According to actual needs, the present invention extracts part of the medium-temperature flue gas from the turning chamber into the hot primary air, and then feeds it into the coal mill. When applied to boilers burning high-iron and high-alkali metal coal, the present invention can effectively reduce the oxygen concentration in the primary air pulverized coal flow, delay the ignition of the pulverized coal, prevent slagging in the area near the burner, and reduce the generation of NOx. At the same time, because a large amount of hot flue gas and part of the cold flue gas are mixed into the primary air, the temperature of the burner area in the furnace and the concentration of alkali metals and iron ions in the furnace flue gas are greatly reduced, further preventing the iron ions from further reacting with the alkali metal-containing ash in the furnace to produce more complex ash with a lower ash melting point, thereby reducing the possibility of coking, fouling, and ash accumulation in the boiler.

[0008] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments: BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a schematic diagram of the cold and hot flue gas mixed combustion system for a high iron and high alkali coal boiler according to the present invention. DETAILED DESCRIPTION

[0010] The embodiments of the technical solution of the present invention will be described in detail below with reference to the accompanying drawings. Unless otherwise specified, the technical terms or scientific terms used in this application should have the common meanings understood by those skilled in the art to which the present invention belongs.

[0011] Example 1, as Figure 1 As shown, a hot and cold flue gas mixed combustion system for a high-speed rail high-alkali coal boiler comprises a hot primary air duct 2, a hot flue gas fan 3, a hot flue gas duct 8, a cold flue gas duct 11 and a cold flue gas fan 12; the hot smoke extraction port 1 is arranged on the turning chamber 9 of the boiler, the hot flue gas fan 3 is arranged on the hot flue gas duct 8, and the two ends of the hot flue gas duct 8 are respectively connected to the hot primary air duct 2 and the hot smoke extraction port 1, the cold smoke extraction port 10 is arranged on the cold flue, the cold flue gas fan 12 is arranged on the cold flue gas duct 11, and the two ends of the cold flue gas duct 11 are respectively connected to the hot primary air duct 2 and the cold smoke extraction port 10, the inlet of the pulverizer 5 is connected to the hot primary air duct 2, and its outlet is connected to the burner 6 through the pulverized coal duct 7, and the burner 6 is arranged on the boiler.

[0012] Furthermore, the hot secondary air duct 4 is connected to the burner 6 .

[0013] The cold smoke extraction port 10 is arranged on the cold smoke duct after the boiler preheater.

[0014] The coal mill 5 is a vertical coal mill.

[0015] The hot flue gas fan 3 and the cold flue gas fan 12 are flue gas recirculation fans.

[0016] Example 2. Based on the mixed combustion system of the above embodiment, the mixed combustion system of this embodiment can improve the blending ratio of high-iron and high-alkali coal in the boiler. For example, when applied to a 600MW-level generator set, based on an annual utilization of 5,000 hours, it can reduce nitrogen oxide emissions by about 350 tons / year and utilize 1.5 million tons of high-alkali metal coal / year. After conversion, it can save the country about 1 million tons of standard coal / year, and can fully and effectively utilize the domestic high-iron and high-alkali coal resources.

[0017] The present invention has been disclosed above with reference to preferred embodiments, but this is not intended to limit the present invention. Any person skilled in the art who, without departing from the scope of the technical solution of the present invention, can make slight changes or modifications to the above-disclosed structures and technical contents to produce equivalent embodiments with equivalent changes, all of which still fall within the scope of the technical solution of the present invention.

Claims

1. A hot and cold flue gas mixed combustion system for high-iron and high-alkali coal boilers, characterized by: The invention comprises a hot primary air duct (2), a hot flue gas blower (3), a hot secondary air duct (4), a hot flue gas duct (8), a cold flue gas duct (11) and a cold flue gas blower (12); the hot flue gas extraction port (1) is arranged on the turning chamber (9) of the boiler, the hot flue gas blower (3) is arranged on the hot flue gas duct (8), both ends of the hot flue gas duct (8) are respectively connected to the hot primary air duct (2) and the hot flue gas extraction port (1), the cold flue gas extraction port (10) is arranged on the cold flue, and the cold flue gas extraction port (10) is arranged on the cold flue after the boiler preheater. A cold flue gas fan (12) is arranged on the cold flue gas duct (11); the hot flue gas fan (3) and the cold flue gas fan (12) are flue gas recirculation fans; the two ends of the cold flue gas duct (11) are respectively connected to the hot primary air duct (2) and the cold smoke extraction port (10); the inlet of the coal mill (5) is connected to the hot primary air duct (2); and the outlet thereof is connected to the burner (6) through the pulverized coal duct (7); the burner (6) is arranged on the boiler; the hot secondary air duct (4) is connected to the burner (6); and the coal mill (5) is a vertical coal mill.

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