Chemical Rotary Kiln

The thickness of the cast on the inner surface of the chemical rotary kiln cylinder is not less than 250mm. The lining includes a number of acidic or neutral anchor bricks evenly distributed axially and fixed on the inner surface of the cylinder. A number of evenly distributed metal anchors are fixed on the inner surface of the cylinder on both sides of the anchor bricks, and then acid-alkali-resistant high-temperature castables are used. The acid-alkali-resistant high-strength castable is connected to the cylinder as a whole through anchor bricks and metal anchors.

The main factors of damage to the lining of the chemical rotary kiln are mechanical stress, thermal stress, high strength, high temperature resistance, chemical erosion, and acid erosion resistance, which can avoid low melting point substances from adhering to the kiln lining.

 

The chemical rotary kiln uses amorphous castables with the advantages of good lining integrity, reliable and safe operation, convenient construction, and low cost. The refractory castables that integrate the properties of light weight, high temperature resistance, heat insulation, and wear resistance not only reduce the consumption of refractory materials and extend the service life of the kiln, but also reduce the operating cost.

Lithium salt,strontium salt rotary kiln,barium sulfide,barium chloride rotary kiln,titanium dioxide rotary kiln

Refractory of Rotary Kiln

1: Selection of refractory materials for lining of chemical rotary kiln system

(1) The furnace temperature of chemical rotary kiln is high. The working temperature is 1100~1450℃, which is a furnace with relatively high working temperature. In occasional working conditions, the furnace temperature may reach 1600℃ or higher.

(2) There are many corrosive components such as H2O, H2S, SO3, SO2 and S vapor in the furnace of chemical rotary kiln. H2S has reducing properties, which imposes strict restrictions on certain impurity components in the furnace lining materials.

(3) Chemical rotary kiln is an acid gas combustion furnace. There is no heat extraction surface inside the furnace. Any large fluctuation under combustion conditions means a thermal shock to the furnace lining. Therefore, the furnace lining is required to have good thermal vibration resistance.

(4) Chemical rotary kiln combustion furnace has strict requirements on wall temperature, which requires the furnace lining material to have good thermal conductivity.

2: Selection of refractory materials for the lining of the chemical rotary kiln system

2.1 Corundum castable material

The lining material of the acid gas reactor of the chemical rotary kiln unit is generally made of corundum castable lining. The reason is that the corundum castable lining not only has a high refractory temperature, but also has good wear resistance. However, due to its poor thermal vibration resistance, it may have problems such as peeling and falling off in a short period of time.

2.2 High alumina brick + corundum brick material

The lining material of the original acid gas combustion furnace of the chemical rotary kiln is high alumina brick + corundum brick material. Its brick joints are one of the weakest links. Due to the damage of the brick joints, the overall deformation and collapse of the masonry often occur. On the other hand, high alumina bricks and corundum bricks are difficult to process and manufacture, and it is difficult to fit some special-shaped parts, and the cost is also high.

2.3 Steel fiber castable material

Steel fiber castable has good fire resistance and has achieved good results. However, in the case of acid gas combustion furnace, this material is prone to problems such as agglomeration and deep cracks.

2.4 Combination of castable and prefabricated parts

The combination of chemical rotary kiln castable and prefabricated parts is a very good solution with the following significant features: ① High temperature resistance (up to 1200-1800℃) and high strength. ② The furnace wall support is hanging type, not easy to deform or fall off. ③ The insulation layer is poured and the working layer is rammed. It can be made into any shape (especially in special shapes). It is easy to construct, and its combined structure is dense and solid, and there is no gap in the kiln wall. ④ When the lining is supported by anchors, the furnace wall can withstand peeling and protrusion, and maintenance is convenient. ⑤ The lining material has good anti-peeling properties and will not embed foreign matter. ⑥ The furnace baking time is short, and the construction is fast and economical.

Alkali-resistant refractory castables are alkali-resistant castables prepared with aluminum silicate materials as refractory aggregates and powders, aluminate cement and admixtures. This type of castable is divided into heavy and light types, with good high temperature performance and alkali erosion resistance. It has been used in large and medium-sized dry cement kiln coal nozzles and kiln mouths, preheaters and pipelines, and its effect is good. In addition, water glass clay refractory castables are also alkali-resistant and can resist the erosion of sodium salt melts. Therefore, it is used in the alkali recovery furnace of the papermaking industry to achieve better results.

Using materials such as fused corundum, zirconium corundum, magnesia, magnesium aluminum spinel, chrome ore and zircon as refractory aggregates and powders, aluminate cement and admixtures are used to prepare castables, crucibles are made, K2CO3 is loaded, and roasted at 1200℃ for 8h to evaluate alkali resistance. When cement and α-Al2O3 powder are the same, the alkali resistance of the material is best for fused spinel, followed by fused magnesia, chrome ore, fused corundum and zirconium corundum; when spinel is used as aggregate and 5%~7% zircon powder is added, the alkali resistance is the best and the sample is almost undamaged. The damage mode is mainly melting.

Heavy alkali-resistant refractory castables use materials such as magnesia-alumina spinel and bauxite clinker as refractory aggregates and powders, and add α-Al2O3 powder; lightweight alkali-resistant refractory castables use low-aluminum clay lightweight aggregates, such as shale ceramsite. The binders of the two castables are CA-70 cement and CA-50 cement, and anti-alkali agents, composite admixtures and ultrafine powders are added at the same time.

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