QHow to choose firebricks?
There are many factors to be considered when you choose the firebricks for your kiln, the most suitable bricks not only can improve the kiln service life but also save your money.
1. It depends on your kiln. The kiln can be divided into new masonry kiln and old kiln maintenance masonry. If the new one, we should know which parts,using temperature, special environment (acid alkali, high pressure,impact, wear and so on) of the firebricks to be used? Then choose the most suitable firebricks. If maintenance for old kiln , it can be based on experiences use of firebricks before, considering whether to use another materials instead, or improving and enhance the firebricks index.
2. According to the use part and working temperature or other speciications such as the cold crushing strength, the porosity, the creep rate, the linear change etc to choose and produce the firebricks to saticefy the production requirements.
3. The proportion of the standard brick and special shaped brick is determined. For example, standard brick is easy to purchase. If the special brick, needs customized mold and mass production, it's a high accurate require to the mold, also express richness and technological experiences of the factory.
QWhy do castable precast blocks have construction advantages?
(1) The compressive strength of castable precast blocks is high.
This performance is about 2 times higher than that of the conventional product.
(2) The thermal shock resistance is good.
The thermal shock resistance of castable precast blocks can be improved by 8 to 10 times.
(3) Excellent wear resistance.
The wear resistance of the castable precast block is superior to the ultra-low cement castable of the same material.
(4) Saving masonry, curing and baking time.
There’s no need on-site pouring, support and disassembly of molds and construction tools, only on-site installation and combination which is convenient and fast.
(5) It is not subject to the environmental temperature limit.
The castable precast block can be installed in any environment with different temperature range in different countries and seasons worldwide.
(6) Easy to replace and disassemble
In the actual production, the damaged part of the precast block can be directly replaced, realizing the desire to replace the instant ignition instantly.
(7) Longer shelf life
Unshaped refractories usually have a shorter shelf life, even in dry conditions, only a few months, while precast blocks greatly extend the shelf life, which is expected to be several years.
(8) Longer service life
Life expectancy is 2 to 3 times longer than ordinary materials, and up to 4 to 6 years, energy saving and environmental protection. The impact resistance is 10 times higher than that of ordinary materials, and the wear resistance is superior to the same level of ultra-low cement material.
QWhat factors should be considered in the selection of lining materials for circulating fluidized bed boiler (CFB boiler)?
The performance of CFB lining materials should have the following requirements:
1. The inner circulation vortex type turbulent bed lining requires high wear resistance, high temperature resistance and erosion resistance;
2. The lining of the inlet section of the high temperature external circulation separator requires high wear resistance and high temperature resistance;
3. The inlet of the medium temperature external circulation separator requires high wear resistance and high temperature resistance;
4. Medium and high temperature external circulation separator cylinders require heat resistance, heat insulation and low thermal inertia;
5. Ignition combustor flue requires high heat resistance;
6. The suspension chamber requires high heat resistance, wear resistance and low thermal inertia.
QWhat are the advantages of refractory plastic?
1. High refractoriness, the refractoriness of aluminium silicate refractory plastic can reach to 1750~1850℃ ,exceed the clay bricks which can be used directly in contact with the flame.
2. Good resistance to shock cold and heat, it won’t be peel when the temperature changes dramatically. The service life of refractory plastic is longer for half year than refractory bricks.
3. Good insulating performance. The thermal conductivity of refractory plastic is smaller than brick, therefore, less heat loss, it can reduce fuel consumption.
4. Good resistance to slag. It can resist the erosion of oxide slag, and the slag is not easy to bond, easy to remove.
5. The anti-shock and wear resistance performance are good. The column used for binding the bottom water cooling pipe and walking beam furnace is not easy to fall off and damage.
6. The masonry is compact.
QWhat are the causes of wear and peeling of refractory bricks in steel blast furnace lining and how to repair it?
Causes of damage to refractory bricks used in blast furnace lining:
1. Mechanical reasons in the blast furnace smelting process.
2. Chemical corrosion such as the reaction between the alkali metal oxide and the refractory brick.
3. High temperature action of the blast furnace itself.
4. In addition, due to the unreasonable design and construction of the furnace wall of the blast furnace itself, for example, poor quality refractory materials, unreasonable operation during the production process etc.
Methods for repairing blast furnace lining
There are three common types of repairs we have for blast furnace walls:
1. Brick masonry method: that is, the medium repairing is to change the cooling wall and the brick lining. The workers enter the blast furnace to lay the furnace lining from bottom to top, but the shortcomings are long cycle, large workload, long production stoppage and poor working conditions.
2. Hard material pressing method: Repairing the middle and lower furnace walls by hard material pressing technology without dropping the line, which is a method for quickly and effectively repairing the local furnace wall.
3. Spray lining method: It is the most commonly used at home and abroad. There are two kinds of spray-filling construction: dry spray method and wet spray method. Generally, the exposed furnace wall is sprayed under the condition of reducing the material line, especially suitable for the unheated part of the upper part of the blast furnace and the large-area furnace wall repair. If the wall damage area is large, it is most suitable to use the spray lining, and the spray lining is more advantageous for the cooling wall blast furnace.
QHow to set the most reasonable proportion of the aggregate when make castable?
There is a great relationship between the fluidity of the unshaped castable and the proportion of the castable trace agent and the material selection, it’s not significant with the ratio of the aggregate. In general, the fluidity of the castable should be considered from the properties of itself first, which is divided into acid, neutral ,alkaline, weak acid, weak alkali and so on. It can greatly improved the fluidity of the castable if add a certain amount of silica fume reduce using amount of the cement and greatly increase strength of the castable, but we all know that most of the silica fume is used as industrial secondary product, because of the quality stablity is not good,it may affect the overall usability of the castable.
Jundao (Henan）New materials Co.,Ltd gave you a suggestion, a test is required for silica fume before using. Only need the detection index of viscosity of the slurry (R2O) and PH value.The viscosity of matrix slurry corresponds to the size of the viscosity of silica fume, the smaller the viscoscity of the matrix slurry, the larger the fluidity value of the castable. In the case of no additives, the flow value is very small when only the silica fume added, which means the slurry and additives should be used simultaneously when using, the fluidity will be perfect.
QWhat's spalling resistant refractory brick?
Spalling-resistant high-Al refractory brick takes high grade bauxite as the main raw material, added into little ZrO2 (ZrO2 is a phase between monoclinic and square type, which can improve the thermal shock stability of the product), and added in a certain ratio of compound binders and additives, by controlling the grain size distribution of the plaster, molding and firing under high temp, this kind of product is with high spalling resistance.
The spalling resistant mechanism is due to the fact that the microstructure of ZrO2 determined its anti-spalling performance.
QHow to select the heat-resisting steel fibers used for steel fiber refractory castables?
Firstly weigh the refractory aggregates, powders, binders and admixtures, and dry-mix for one minute;
Secondly add water and wet mixing, and evenly spread the steel fibers into the material, and do not clump;
Finally mix for one minute can be discharged.
The total mixing time must not be less than 5 minutes. When the vibrating rod is used for molding, the vibration direction should be staggered to make the distribution of the steel fiber reasonable, which can improve the performance.