1, the current shortcomings of hot melt slag insulation furnace lining
At present, the application time of direct cotton production from metallurgical hot slag is not long in China. Many enterprises are in the early stage of industrialization, and the realization of industrialization is rare. In practice, the operation effect of hot slag liquid holding furnace is not ideal, mainly due to the fast consumption of furnace lining and short furnace life. Most of the number of 10d, less 6~7d, affecting the efficiency and benefit of the whole cotton production line.
The working process of the hot melt slag holding furnace is as follows: every other fixed time period, such as 2~4h, the hot slag liquid flows into the slag inlet, and at the same time, the slag discharge port continues to flow out in a specific amount. The slag level in the holding furnace decreases continuously with the outflow time, and when it drops to a certain position, new slag is filled in.
In short, in the production process, the inflow of slag is intermittent, and the outflow of slag is continuous. The technological process causes damage to the lining of the insulation furnace: (1) Mechanical damage: frequent new slag liquid replenishment causes strong erosion of the lining; ② Heat damage: when the new slag is filled, the lining temperature increases, when the slag is drained, the lining temperature decreases, and the lining is damaged by thermal shock due to thermal expansion and contraction; ③ Chemical etching: on the one hand, the hot melt slag reacts more or less with the furnace lining; On the other hand, when the slag is drained, the lining is exposed to the air, and some materials such as carbon bricks will undergo strong oxidation reaction and lose.
2. Ideas for solving problems
According to the above problems, the idea of hanging slag on furnace wall and keeping heat in furnace bottom is put forward. Furnace wall hanging slag: In the insulation furnace barrel body part, a certain temperature gradient is formed between the inner wall of the furnace lining and the water jacket of the furnace shell. This temperature gradient forms a protective layer of slag on the inner wall of the furnace lining, which effectively protects the furnace lining. Bottom heat preservation: Because the bottom lining of the heat preservation furnace is always covered by a slag layer, the probability and degree of damage is far lower than that of the side wall, and the consideration is to minimize heat loss. Therefore, the bottom lining of the insulation furnace should be ensured that no leakage can occur.
3. Implementation plan
The cooling water flowing through the water jacket is used as a carrier to carry away the heat energy from the furnace lining. The carbon brick has the advantages of high temperature resistance and thermal conductivity but poor oxidation resistance. The main component of clay bricks is silica, which is an acidic refractory material with strong oxidation resistance and almost no chemical reaction with hot melt slag, but it has weak high temperature resistance and poor heat conductivity.
The ideal state is that when the hot slag liquid is filled with the insulation furnace, a slag protection layer is formed on the inner wall of the clay brick lining, and the appropriate temperature gradient makes the slag layer maintain a certain thickness to protect the furnace lining. The role of clay brick in the lining is a sacrifice layer. Even if there is no good slag protection layer on the clay brick layer, the lining can have a certain service life because of its oxidation resistance and non-reaction with hot melt slag. When the clay brick layer is consumed to a certain extent, it can be replaced with new bricks.
The bottom lining of the insulation furnace is always covered with slag layer, and the carbon brick will not be oxidized and has excellent thermal stability in the absence of oxygen. Under the carbon brick is high aluminum brick, high aluminum brick has the characteristics of high temperature resistance and good heat preservation, can ensure that the bottom of the furnace will not leak while not causing the bottom lining to heat too much.
The bonding materials used between different materials are different. High aluminum castable is used between the steel shell at the bottom of the thermal insulation furnace and high aluminum bricks; Carbon ramming material is used between the steel shell of the thermal insulation furnace barrel and the carbon brick. Carbon ramming material is used between carbon brick and clay brick to ensure good heat transfer and heat preservation performance respectively.