A low-nitrogen combustion modification method for a circulating fluidized bed boiler

A circulating fluidized bed, low-nitrogen combustion technology, applied in fluidized bed combustion equipment, combustion methods, and fuels burned in a melted state, etc. The effect of reducing NOx emission concentration, improving economy and environmental protection, and reducing consumption of reducing agent

Active Publication Date: 2016-03-30
HUANENG CLEAN ENERGY RES INST
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] Due to factors such as large changes in coal types and unreasonable adjustment of air volume ratio for existing circulating fluidized bed units in China, it is difficult for many power plants to meet the standards
In the actual operation process, although some units adopt the scheme of primary and secondary air staged combustion, due to the high temperature in the dense phase area, the proportion of primary air to the total air volume has to be raised to 60% or even higher, which is not conducive to recovery The formation of the atmosphere is not conducive to the suppression of the formation of nitrogen oxides
Due to the considerable amount of CFB boiler NO x The emission concentration exceeds 200mg / m 3 , need to install SNCR denitrification system, which will significantly increase the operating cost of the enterprise and the transformation period is long, and the initial investment in equipment is huge

Method used

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  • A low-nitrogen combustion modification method for a circulating fluidized bed boiler
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  • A low-nitrogen combustion modification method for a circulating fluidized bed boiler

Examples

Experimental program
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Effect test

Embodiment 1

[0063] see Figure 1 to Figure 6 , involving a 480t / h circulating fluidized bed boiler, the boiler burns bituminous coal with a dry ash-free base Vdaf20%, the secondary air of the boiler is divided into two layers SA1 and SA2 in the height direction of the dense phase zone 1 of the furnace, and the primary air The PA volume accounts for 60% of the total wind TA volume, and the NOx emission concentration during operation is 250mg / m 3 .

[0064] The primary air-cooled PAC passes through the air preheater 12 to become the primary hot air PAH, and then is sent from the air chamber 3 as the primary air PA to the dense-phase zone 1 of the furnace; the secondary cold air passes through the air preheater 12 to become the secondary hot air SAH, and then is divided into two paths, All the way from the bed burner 11 as the bed burner air SUBA into the dense-phase zone 1 of the furnace, and from the secondary air duct 8 as the secondary air SA into the dense-phase zone 1 of the furnace. ...

Embodiment 2

[0075] Involving a 1024t / h circulating fluidized bed boiler, the boiler burns dry ash-free base Vdaf40% lignite, the secondary air of the boiler is divided into two layers SA1 and SA2 in the height direction of the furnace dense phase zone 1, and the primary air PA The air volume accounts for 55% of the total air TA volume. There are two rows of secondary air outlets 7 on the back wall and the front wall of the boiler respectively. The NOx emission concentration during operation is 350mg / m 3 . To reduce NO in boiler flue gas x The emission concentration is high, and the SNCR technology is used for denitrification, and the annual urea consumption is 8,000 tons.

[0076] Carry out low-nitrogen combustion transformation on the boiler, the specific transformation includes:

[0077] The primary air-cooled PAC passes through the air preheater 12 to become a primary hot air PAH, and then is divided into two paths, one path is sent from the bed burner 11 as the bed burner air SUBA t...

Embodiment 3

[0081] Involving a newly built 410t / h circulating fluidized bed boiler, the boiler burns anthracite with a dry ash-free base Vdaf10%, and the boiler secondary air separation and smoke furnace dense-phase zone 1 are divided into four layers SA1, SA2, SA3, SA4 in the height direction The air distribution plate 4 of the primary air system PAS is supplied with a bell-type air cap 5, the distance between the bell-type air caps 5 is 200 mm, and the outermost ring of the air distribution plate 4 is built with a height of 400 mm and a width of 400 mm. Refractory wear-resistant material boss 6.

[0082]Primary air PA accounts for 40% of total air TA, secondary air SA accounts for 50% of total air TA, bed burner air SUBA accounts for 10% of total air TA. The primary air-cooled PAC passes through the air preheater 12 to become primary hot air PAH, and then is divided into two paths, one path is sent from the bed burner 11 as the bed burner air SUBA to the dense-phase zone 1 of the furnac...

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PUM

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Abstract

The invention discloses a low-nitrogen combustion transformation method for a circulating fluidized bed boiler. The method comprises the following steps: simultaneously transforming a low-share primary air system (PAS), an accurate secondary air feeding system (SAS) and an over-bed combustor supplemented air system (SUBS); arranging a bell jar type air cap on an air distribution plate, and building a fire-resistant and wear-resistant material lug boss at the outermost circle of the air distribution plate; independently feeding secondary air (SA) according to a region, regulating the amount of the SA through a regional SA total flow control device and an independent SA accurate flow control device respectively, and arranging three or four layers of SA ports along the height direction of a dense-phase region of a hearth, wherein an air source is primary cold air (PAC), and the amount of over-bed combustor air (SUBA) accounts for 5-10 percent of the amount of total combustion air (TA). After transformation, the proportion of primary air to secondary air can be flexibly regulated, combustion air feeding can be accurately controlled, and low nitrogen oxide emission level and high combustion efficiency are realized finally. The boiler can operate, and the characteristic of environmental protection can be remarkably improved without additional equipment. The method has the advantages of low investment cost, short transformation period, no operation cost, stability in operation of the boiler and the like.

Description

technical field [0001] The invention belongs to the technical field of circulating fluidized bed boiler environmental protection, and in particular relates to a low-nitrogen combustion modification method of a circulating fluidized bed boiler. Background technique [0002] Coal is the main source of primary energy in my country, and coal-fired power generation is the main part of coal utilization in my country. Coal combustion will produce many pollutants, such as sulfur dioxide, nitrogen oxides and soot, among which nitrogen oxides are one of the main sources of acid rain. With the rapid development of my country's economy, the discharge of pollutants has become more and more serious, which has brought great troubles to people's lives. In view of this, the state has successively issued environmental regulations to strictly control the discharge of pollutants. In the newly promulgated "Emission Standards of Air Pollutants for Thermal Power Plants" (GB13223-2011), it is cle...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): F23C10/00F23C10/18F23C10/20
Inventor 黄中江建忠徐正泉肖平孙献斌
Owner HUANENG CLEAN ENERGY RES INST
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