Effect of the annular gap size in the downcomer and upcomer
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What factors determine the annular gap size in the downcomer and upcomer of the water-coal slurry process, and what are the consequences if it is too small or too large? Welcome, experts, to actively discuss! The riser and downcomer tubes of the company’s furnace are severely scaled; it is being considered whether a too-small annular gap could be the cause, in addition to factors related to the type of coal and water quality.
It’s a good question that deserves consideration by those involved in gasification. The design principles for the gap between the downcomer and the upcomer, as well as the mechanisms behind dust accumulation in these components, should be thoroughly analyzed by everyone.
We have not yet encountered the problem of scaling in the rising and descending tubes you mentioned. However, due to the low liquid level in the quench chamber, we enlarged the rising tube, and the liquid level in the quench chamber has improved significantly
A larger annular gap facilitates gas-liquid separation and can alleviate water entrainment in the gasification furnace. However, when the annular gap becomes larger, the residence time of syngas in the gasifier is too short, resulting in poor washing efficiency; moreover, it is worth considering whether this will affect the water vapor ratio. A balance should be sought between the two.
The annular gap is large, the gas flow velocity is low, and the gas stays in the extremely cold chamber for a long time.
The annular gap design of the rising and descending tubes in a conventional gasification furnace is determined based on factors such as the coal quality, load, and pressure of the furnace. During normal operation, it is essential to follow the design specifications strictly; one should never alter the operating conditions, processes, or increase the load too rapidly. Such as switching to coal with a higher ash content, using fluxes as aids, or overloading, etc. All of that will lead to accelerated scaling. Of course, to address scaling in the system, it is more important to use high-quality flocculants and scale-inhibiting dispersants, as well as to ensure the quality of the graywater; only by doing so can the rate of scaling be effectively reduced and the operating life of the gasifier extended.
Hello, could we become friends? I’m facing the same issue as you, and it would be convenient to communicate
Hello, Hiyou – which manufacturer do you belong to? We are also planning to carry out corresponding modifications, and we would be very grateful if you could provide us with the relevant data for those modifications.
Which factory do you guys work for? Have you resolved the issue with your operation? Could we have further discussions?