Circulating fluidized bed boiler and material return abnormity adjusting method thereof

Abstract

A circulating fluidized bed boiler and an adjustment method for abnormal material return, comprising a furnace, a separator, a material return standpipe, a material return valve and a tail flue to form a circulating fluidized bed boiler. The furnace, the separator, the material return standpipe and the material return valve form an external circulation loop. The adjustment method for the abnormal return of circulating fluidized bed boiler: lower the height of the rising section of the return valve by 300mm, add a return sealing air duct at the bottom of the separator and the upper part of the return standpipe, set up a purge device in the horizontal flue, The ash discharge pipe is installed in the hole on the air distribution plate of the return valve, and the ash discharge pipe is installed at the lowest part of the return air chamber. After cleaning out the debris of the return valve, start it again. Stop the furnace to check the condition of the wind cap and repair the wind cap in good condition. The above measures can solve the problem of abnormal material return caused by different reasons. The invention is simple in operation, easy to popularize, easy to carry out equipment transformation and low in cost, and is widely applicable to large-scale circulating fluidized bed boilers.

Description

technical field [0001] The invention relates to a circulating fluidized bed boiler and an adjustment method for abnormal material return thereof, in particular to a large circulating fluidized bed boiler and an adjustment method for abnormal material return thereof. Background technique [0002] 1. Circulating fluidized bed boilers have the advantages of wide fuel adaptability, high combustion efficiency, high-efficiency desulfurization, low nitrogen oxide emissions, simple coal feeding system, and high comprehensive utilization of ash and slag. In the past 10 years, circulating fluidized bed boilers have been widely used in my country widely used. However, looking at the operation of circulating fluidized bed boilers in our country, the problems of high failure rate and short operation period have become a common phenomenon. Among them, the abnormal failure of returning materials occurs frequently, which seriously affects the normal production. In severe cases, the furnace ...

AI Technical Summary

Problems solved by technology

[0003] 2. Abnormal return of circulating fluidized bed boiler:

[0005] Abnormal situation of return material: when the circulating ash in the descending section of the return valve is insufficient, the circulating ash in the ascending section is also lacking, and the loosening wind will reverse the riser to the separator. At this time, the pressure in the ascending section of the return valve is less than or equal to the ascending section The pressure makes it difficult or even interrupted to return the material, that is, the abnormal phenomenon of the return material occurs

In another case, when the circulating ash in the descending section is at a high material level or has debris, if the fluidizing air in the ascending section and the loosening air volume in the descending section decrease, the circulating ash in the descending section will be compacted instead of being in a loose state , so that there will be no circulating ash replenishment in the ascending section, so that the return material will be suspended, that is, the abnormal phenomenon of return material will occur

[0006] 3. The hazards of abnormal return of circulating fluidized bed boiler:

[0010] 4) Due to abnormal material return, the main steam temperature of the boiler changes greatly periodically, and the inner wall temperature of the high-temperature components such as the automatic main steam valve, regulating valve, and regulating stage of the steam turbine also fluctuates greatly, resulting in alternating thermal stress and thermal stress. Deformation, reducing the service life of equipment; at the same time, the main steam pressure fluctuates, which makes the water wall, steam drum, superheater, main steam pipeline, etc. of the boiler pressure-bearing parts prone to creep and cracks

[0011] 5) Fluctuations in the bed temperature can also easily cause coking at high and low temperatures. When the material cannot return to the furnace in time, it is easy to form high-temperature coking. If the coke produced is small and blocks the slag pipe, the operator will easily cause burns when poking the slag. If a large area of ​​coking is formed, the furnace must be shut down

[0012] 6) If the abnormality of the return material is not adjusted properly, a large amount of material will accumulate in the furnace until the primary air volume reaches the rated output, and the bed material still cannot reach the fluidized state. At this time, the phenomenon of pressing the bed is forced to stop the furnace to discharge slag

[0013] 4. The magazine "Energy Technology and Management" published a paper "Discussion on Stable Operation of Large CFB Boilers" (author Li Weihua). It is mentioned that the return wind is reversed and the circulating ash separated by the separator is sealed, so that the circulating ash accumulates at the bell mouth of the lower part of the separator, causing the suspension of the return and causing the abnormal return of the material, but the specific solution is not mentioned in the article

However, there is no mention of the solution to the reverse flow of the return air. A sealed air duct should be installed on the upper part of the return riser at the lower part of the separator, but this is not mentioned in the article.

[0015] 6. The magazine "Operation and Management" published a paper "Analysis on the Measures to Prevent the Interruption of the Return of Circulating Fluidized Bed Boiler" (author Guo Zongtao). , poor fluidization

However, the article does not mention the problem and solution of the return wind blowing back. It should be adopted to install a sealed air duct on the upper part of the return riser at the lower part of the separator, but this is not mentioned in the article. This is the shortcoming of the article.

[0016] 7. Obviously, each power plant has different adjustment methods for abnormal material return, each has its own disadvantages, and its scope of application is small

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