- Time:Jan 28, 2023
Generally, the melter-gasifier is divided into four parts: drying area, fluidized combustion area, tuyere area and hearth.
The temperature in the drying zone is 1000-2000°C, the coal is decomposed and the volatiles are removed. The furnace lining in this area is very strongly affected by the mechanical impact of the charge, and is also eroded and corroded by the dust-containing gas. Therefore, the furnace lining is required to be wear-resistant. In this area, high alumina bricks with Al2O3 content of 55%-65% can meet the requirements. It is the same as the kiln lining of the reduction shaft kiln. In order to improve the service life, the Fe2O3 content is required to be as low as possible to prevent the lining from embrittlement or powder change.
Fluidized combustion zone temperature can reach 1600-1700 ℃. The furnace charge is fluidized, which seriously scours the furnace lining, and the refractory furnace lining bears a large thermal load and high temperature wear. The ISCOR company in South Africa used magnesia-carbon bricks in this part, which fell off seriously due to frequent furnace shutdowns and furnace openings. The SiC brick combined with Si3N4 with excellent thermal shock resistance and thermal stability and erosion resistance should be used as the furnace lining.
The tuyere of the melter gasifier is operated with oxygen, and the heat load of the tuyere brick is high and the working conditions are harsh. It has a strong oxidizing effect on carbon-containing refractory materials. Slag and molten iron are formed there, so the tuyere bricks at high temperature are strongly corroded. The tuyere is made of SiC brick, and the furnace from the upper part of the tuyere to the manhole is made of magnesia-carbon brick, which has a phenomenon of hydration. It is recommended to use SiC brick combined with Si3N4 as the lining. The tuyere is combined and turned, and the use of β-SiC bricks is very effective. The tuyere and the area above it should use silicon carbide bricks and chrome corundum bricks. Sialon combined with corundum brick should also be a very good choice.
The refractory lining of the furnace bottom, hearth and iron mouth of the melter-gasifier is always in contact with the high-temperature molten iron and slag, and the erosion is the main reason for the damage of the refractory. The refractory materials used are equivalent to those of blast furnaces, mainly microporous carbon bricks and a layer of ceramic cups. Al2O3-SiC-C materials are still used in the tap hole, and these refractories are the same as those used for the bottom and hearth of the blast furnace.
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