Development of 25t/h circulating fluidized bed boiler

Development of 25t/h circulating fluidized bed boiler

Abstract: This article mainly describes the structural characteristics and technical characteristics of our company 25t/h CFB boiler.

Guan Jianci: circulating fluidized bed, circulating combustion, separator

1 Preface

Circulating fluidized bed combustion technology is a new efficient clean coal technology developed in recent years, is also the national energy law to promote the use of coal combustion technology, after more than 10 years of theoretical study and practical experience, fully equipped with the commercial conditions, it has high efficiency, energy saving, low pollution etc..

SHXF25-2.5/400-A I of CFB boiler is our company according to the market information feedback and user needs optional items, the boiler is used by our company Institute of Engineering Thermophysics and our company jointly developed circulating fluidized bed combustion boiler technology independent research and development of new products. On the basis of summing up the experience of design, commissioning and operation of circulating fluidized bed boiler developed by our company in the past ten years, the stability and reliability of the product have been further improved.

2, Boiler overview

2.1 General layout and design features

SHXF25-2.5/400-A I of CFB boiler with double drum natural circulation structure, parts factory, site assembly. The center elevation of the upper boiler barrel is 12000, and the center elevation of the lower barrel is 4800. After installation, the overall size is 13190*8580*13650 (length * width * height).

The core structure of a circulating fluidized bed boiler is composed of fluidized bed separator, and refeeder circulating combustion system, fuel into the dense phase zone mixed with the air flow and combustion, high temperature flue gas hot burning to carry large amounts of solid particles erosion in dilute phase zone, while burning, while the transfer of heat to the heating surface heating of the refrigerant (water), unburned solid particles into the ashes separator is collected, through revert back into the dense phase zone and cyclic combustion, improve the combustion efficiency and the desulfurization efficiency greatly, combustion of solid particles with high temperature flue gas escaping out separator, convection heating surface and erosion of cast iron economizer, air preheater, tail heating surface, the dust is discharged into atmosphere.

2.2 structure description

2.2.1 dense zone: dense area is a square fluidization chamber, size is 2500 x 1300mm, this section all adopts circulating fluidized bed special HF wear-resistant castables pouring. Coal feed port and discharge port and return tuyere two are arranged in the. It is at the bottom of the air distribution plate, the air distribution plate is installed on the hood and the slag discharge pipe. A flow through orifices into the combustion chamber, the flow and provide combustion air to the fuel.

2.2.2 dilute phase area: the dilute phase area is rectangular section, size is 3820 x 2120mm, around the water wall, absorb the fuel combustion about 50% of the heat release. The flue gas velocity is 5.44m/s

2.2.3 separator: the boiler uses high temperature separation system, so that the boiler structure is more compact, more convenient operation regulation. The working environment temperature is 900 degrees, and the wear resistance and high temperature material are used for casting, the resistance drop is 1600Pa.

2.2.4 feeder: the material return of circulating fluidized bed boiler is carried out by the return feeder, and the back feeder consists of two parts: standpipe and valve. The boiler adopts the non mechanical pneumatic conveying valve and U valve. The working temperature is 950 to 800 DEG C to prevent slagging.

2.2.5 superheater

Located in high temperature superheater separator, the suspension structure of vertical, low temperature section adopts carbon steel, high temperature alloy steel used, the comb shaped plate fixed structure and clamp. The superheater pipe made of 1Cr18Ni9Ti material, the comb shaped plate by 1Cr18Ni9Ti, so as to prevent gas burning, prevent pipe screen swing.

The high temperature cyclone separator, flue gas dust content is low, there is no local wear of superheater. In front of the superheater with anti flat grinding rare earth alloy steel material, prevent wear. In order to ensure the superheated steam can be adjusted, using surface type temperature reduction.

2.2.6 convection tube bundle and economizer

The three flue gas convection tubes and mixed scour. Economizer mining wear resistance, resistance to oxidation and corrosion of cast iron economizer.

2.2.7 furnace wall

The furnace wall is made of a heavy furnace wall, which is made up of outer red brick and inner clay firebrick. The furnace roof is hung with concrete structure and is hung on the top combined steel frame by the hook.

2.3 commissioning rectification

At the beginning of the product in the design, first used heat-resistant steel integralpouring refeeder and rectangular fluidized bed, due to expansion of revert to heat-resistant steel in the design of the reserved operation appears insufficient, dust ash leakage problem, after rectification for refractory concrete cast-in-place refeeder after running smoothly. In addition because the user is at the initial stage of operation due to the plant, the superheater structure caused by superheater tube problem, we according to the process of water treatment technology and local production, the replacement of the steam water separation device, the original design of the shutter plate + two level separation structure for cyclone + blinds + three hole plate separator the structure, ensure the quality of steam superheater inlet, superheater more safe and reliable operation.

3 .Technical specifications for products

1, product model: SHXF25-2.5/400-A I external circulating fluidized bed boiler

2. Rated evaporation: 25t/h

3, superheated steam temperature: 400

4, feed water temperature: 105

5, exhaust temperature: 150

6. Design fuel: A I (class I bituminous coal)

7, one air temperature: 130

8 , two air temperature: 30

9, Design thermal efficiency: 83.6%

4 , Operation situation

The boiler after debugging after rectification, delivered to the user, in the actual operation of more than a year in Shanxi, Henan Pingdingshan anthracite users Inferior Bituminous coal and local wood and coal, ensure the stable combustion can be stabilized, the boiler output is about 24 ~ 27t/h, steam pressure stable at around 2.5MPa, the steam temperature control in 380 ~ 410 C, ensure the steam power generation and production process.

5, Boiler thermal and environmental performance test

In March 2002, the quality supervision of Shanghai Industrial Boiler Research Institute of machinery industry industrial boilers and environmental protection product quality supervision and inspection center and the Shanghai industrial boiler environmental protection equipment inspection station of the product of thermal and environmental performance test of our company, the test results are as follows:

Table 1 Thermal Test

Rated evaporation

Rated steam pressure

Superheated steam temperature

thermal efficiency

Exhaust gas temperature

Feed water temperature

test result

Twenty-five point four

Two point four

391 C

83.49%

153 C

98.5 DEG C

Examination result

More than 24.25

More than 2.25

380~410 DEG C

More than 74%

Table 2 environmental testing

Converted soot

Emission concentration

Mg/m3

Converted SO2

Emission concentration mg/m3

Converted NOx

Emission concentration mg/m3

Converted initial soot concentration

Mg/m3

Blackness

Lin

Rated load

One hundred and ninety point one three

Three hundred and thirty-six point nine nine

One hundred and thirty-nine point seven five

Fourteen thousand and ninety-five point two zero

< 1

GWPB3-99

200 (two categories)

Nine hundred

/ /

Fifteen thousand

< 1

Table 3 noise test

Noise of boiler induced draft fan

Noise of boiler blower

Boiler room noise

test result

84dB (A)

110dB (A)

76dB (A)

Examination result

90dB (A)

85dB (A)

6 Conclusion

1, the product uses high efficiency, clean coal technology, with sufficient combustion, high thermal efficiency, load regulation ratio, SO2 and NOX emissions, coal adaptability and other characteristics.

2, through the user test operation reflects, coal saving effect is remarkable, sufficient output, load regulation is good, rise fire, pressure fire is simple and convenient, boiler site labor condition is good.

3, through the mechanical industry boiler and environmental protection product quality supervision and Testing Center for thermal and environmental testing, boiler meets the relevant national industrial boiler and related standards. The test of boiler thermal efficiency is 83.49%, 8.49 percentage points higher than the national standard value.

4, the cyclone separator technology is the first in the level of circulating fluidized bed boiler. The main technical indicators have reached the domestic advanced level.

5, after more than a year of operation shows that the product design, manufacture and operation is successful, and achieved good results, the success of the project development is to fill the gaps in our series of circulating fluidized bed boiler.

6, external circulating fluidized bed combustion technology after ten years of development and perfection, has made great progress, the product has been based, large-scale commercial production but, as a new technology, the key technology of gas-solid separation, heat transfer and high temperature materials back still need to further strengthen the basic research, make the product stable and reliable.