Lightweight Acid Resistant Castable

As chimneys develop towards height and clustering, and the addition of desulfurization or denitrification equipment, the requirements for chimney and flue lining refractory materials are more stringent than before. Improving the performance of these refractory materials has become an important issue.

The fuel has changed from coal to oil, and the chimneys of heavy chemical industries have been clustered, tall and large, so the chimney lining materials are required to be improved as follows:

1) Develop lining materials that are resistant to corrosion, especially sulfuric acid corrosion;

2) Can be constructed in high or complex places;

3) Economical and cheap.

The chimney lining is required to be lightweight, mainly using lightweight clay clinker blocks or siliceous blocks; the flue uses amorphous refractory materials.

 

This type of amorphous refractory material uses Portland cement or alumina cement as a binder. Due to the use of heavy oil with high sulfur content as fuel, sulfuric acid in the flue gas reacts chemically with the flue lining to generate 3CaO, A12O3, 3CaSO4, 32H20, causing the lining surface to peel off.

To prevent sulfuric acid corrosion, acid-resistant castables with sodium silicate as a binder are used. The disadvantage is that the acid penetrates into the castable, but the appearance does not change.

Recently, air pollution has become a problem, and regulations have been made for SOx and NOX in exhaust gas. Therefore, the lining bricks are required to resist not only sulfuric acid corrosion, but also acid corrosion.

At present, in order to deal with a large amount of waste gas, wet smoke exhaust and bowl removal devices are almost used. The waste gas composition after these devices is very complex, so refractory materials are required to have. Performance:

1) Sulfuric acid erosion;

2) Hydration resistance;

3) Alkali salt resistance (Na2S04 generated by absorption liquid);

4) Hydrochloric acid erosion resistance.

As chimneys develop towards towering and clustering, refractory spray coatings are often used to make linings, generally with silicate cement or aluminate cement as a binder, and water glass as a binder when there is a corrosion protection requirement. According to the use requirements, lightweight aggregates or refractory dense aggregates (or refractory acid-resistant aggregates) are used respectively, and lightweight acid-resistant castables are used for the lining of tall chimneys.

Lightweight acid-resistant castables are acid-resistant castables for chimneys. They are a new type of anti-corrosion casting material. They have good workability, convenient construction, moderate initial and final setting times, and continue to increase in strength after high-temperature baking. They are also impermeable and acid-resistant. Lightweight acid-resistant refractory castables can be used as both acid-resistant castables and refractory castables without an insulation layer. Lightweight acid-resistant refractory castables are composed of lightweight aggregates, powders, binders and additives, and the main component of the binder is water glass. The light aggregate structure has a large porosity, a rough surface, and a particle size of about 5mm. The water absorption rate and hygroscopicity of the aggregate and powder are large, so the fluidity is poor after mixing according to the mix ratio. Lightweight acid-resistant refractory castables have good physical and chemical properties, with low bulk density, fast solidification after adding water, high use temperature, compressive strength increases with the increase of temperature and acidity, small thermal conductivity, small linear expansion coefficient, etc. Since lightweight acid-resistant refractory castables have the above high-quality properties, of course, their requirements for transportation and warehouse management are relatively high.

Lightweight acid-resistant castables are made of acid-resistant aggregates, powders, micropowders, acid-resistant additives, curing agents and various auxiliary materials that are processed, mixed according to a certain particle size distribution, and prepared with water or a binder. The product has the characteristics of high compressive strength, good acid corrosion resistance, low water absorption, light insulation, and heat resistance. It is currently an ideal special acid-resistant material for the lining of desulfurization and warm dust removal chimneys.

Product specifications: divided into single and double components. The single component is prepared with water, and the double component is prepared with a binder.

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