Combined fluidized bed slag cooling apparatus

Abstract

The invention relates to a combined fluidized bed slag cooler, which comprises a body, a wind box, an air distributing device, a slag inlet pipe, a slag outlet pipe, an air inlet pipe and an air outlet pipe. The body is provided with the slag inlet pipe, and the bottom of the body is connected with the slag outlet pipe. The lower part of the body is provided with the air distributing device and connected with the wind box of the air inlet pipe, and the top of the body is connected with the air outlet pipe. The slag outlet pipe is provided with a spraying pipe for air intake inside to make the three working areas with different flowing states formed from the lower part to the upper part in the body, the lower part is a spraying area, the middle part is an annular fluidizing area, and the upper part is a suspending and settling area. The upper side of the spraying pipe is provided with a guide pipe. The outlet of the slag outlet pipe is provided with a mechanical slag outlet valve or a conveyor. The transverse and longitudinal mixing of gas-solid two-phase in the bed is obviously strengthened under the coaction of spraying air and fluidizing air. The problems of poor transverse mixing, easy accumulation of local bed materials, delamination, aggregation and the like of the fluidized bed slag cooler are solved. The furnace slag granules can be sufficiently and effectively cooled. The combined fluidized bed slag cooler is used for cooling bottom slag of a CFB boiler or other high-temperature solid granular materials.

Description

technical field [0001] The invention relates to a cooling device for high-temperature solid granular materials, in particular to a cooling treatment for CFB boiler bottom slag. It is an innovation of the traditional fluidized bed slag cooler, which makes the bottom slag cooling of CFB boiler more efficient and safer in operation. Background technique [0002] As one of the most popular clean coal combustion technologies today, fluidized bed combustion boiler technology (including circulating fluidized bed CFB and bubbling fluidized bed BFB boiler technology) has risen all over the world in recent years, developing rapidly and catching fire. In particular, CFB boilers are making increasingly prominent contributions to human society in terms of energy saving and emission reduction. However, the cooling and treatment of the bottom slag discharged from CFB boilers is still lacking. The slag cooling equipment - slag cooler has become one of the most difficult equipment and techn...

AI Technical Summary

Problems solved by technology

However, due to the situation of high coal ash content, coarse ash particles, and high bottom slag share brought about by my country's special national conditions, it is impossible to take advantage of this advantage

According to the survey, most of the coal particles fed into the CFB boiler are too coarse to meet the design particle size requirements, which is the root cause of the difficulty in the normal operation of the fluidized bed slag cooler, making them suffer from slagging, wear, blockage, Difficult slag discharge, high slag discharge temperature, etc. sometimes have to use manual intermittent slag discharge, which affects the stable operation of the boiler, and also causes damage to the environment and people, causing users to lose a lot of money

The reason for this situation, in addition to the above-mentioned specific national conditions and other external factors, most designers have ignored a deeper problem, that is, it is not reasonable to use a fluidized process to cool the CFB boiler bottom slag, and there are the following defects : a. The design and structure of the flat-bottom air distribution device is difficult to achieve perfection, and many abnormal fluidization phenomena are prone to occur, such as throttling, channeling, stratification, local dead zones, etc., which bury potential safety hazards; b. The part of the gas required for the minimum flow rate for fluidization passes through the bed in the form of bubbles and then breaks and escapes at the upper interface, resulting in a short circuit of these gases, failing to fully mix and react with the bed particles, reducing the heat and mass transfer rate, cooling The effect is weakened; c. The longitudinal and transverse mixing of the bed are very different, the transverse mixing is poor, the transverse movement of air bubbles and particles is hindered, the transverse partial velocity of the particles is almost zero, and the uniformity of fluidization is reduced; d. It is not suitable for handling coarse particles Larger proportion of wide screened materials, otherwise more air volume is required to completely fluidize them, resulting in increased fan energy consumption and increased wear of bed facilities

[0003] Chinese Patent No. 200420116020.7 document discloses "a bottom slag cooler for circulating fluidized bed boiler", and Chinese Patent Application No. 02114069.3 document discloses "air trough type slag cooler". bed) technology to cool the slag, but the flow pattern of the classic spouted bed cannot be seen in the structure, that is, there is no obvious central spouting zone and surrounding annular zone in the bed section

On the other hand, although the single spouted bed technology is good at handling coarser granular materials, the stability of the spouted bed is not as good as that of the fluidized bed, and the bubbles generated are larger than those of the fluidized bed—that is, the gas is more likely to short-circuit, and the gas-solid mixture changes. Poor heat transfer and mass transfer rate slow down, reducing the cooling effect

Moreover, if the spouted bed is not matched with the conical plate structure, it is easy to have a dead zone at the bottom, which affects work safety

In addition, the Chinese Patent No. 200520046425.2 document discloses a "jet bed wind-water combined slag cooler", which uses a jet bed to cool slag. This technology uses inclined air distribution plates and directional jets to remove coarse particles, but its overall flow pattern is still flow. The scope of the chemical bed, so the cooling effect is not ideal

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