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.
QHow to set the most reasonable proportion of the aggregate? The most reasonable proportion of the high strength, good fluidity 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.
QCharacteristics of safety work for blast furnace construction
Characteristics of safety work for blast furnace construction
The construction of blast furnace masonry is a complicated production process. Due to the fixed "product", the working environment is changeable and the man-machine mobility is large. The multi-type work is three-dimensional cross operation in the process, there are many special facilities and temporary facilities, and the personnel are concentrated. Therefore, there are many unsafe factors.
1. The construction site is narrow and the working environment is poor.
The blast furnace engineering structure is complex, the layout of the production process is relatively compact, and the amount of refractory materials is large. Due to the limitation of plane and space, the construction site of the furnace construction project is very narrow, and it is required to organize the transportation and masonry of several thousand tons of refractory materials in a limited plane position. Most of the furnace builders are constructed in sealed metal containers. At the same time, natural lighting is insufficient, ventilation conditions are poor, and sometimes it is directly corroded and threatened by high temperature, smoke, toxic gases, chemical materials and so on.
2.There are many sources of accidents, very dangerous.
The blast furnace masonry varies greatly depending on the size of the furnace and the type of furnace. The construction scheme and operation method are also very different. It is generally a high-altitude crossover operation, and often is built on scaffolding, operating platforms or hanging panels. The furnace is up to several tens of meters, not only the construction site is narrow, but also often the furnace construction and other professional cross-operation or multi-layer operation, which increases the source of the accident and unsafe factors.
3. Short construction period
The furnace construction of the blast furnace is often one of the last major processes before the whole project is put into production. The construction period of the delay of the previous process is often compensated by the construction period of the furnace, so the construction period is very short, forcing the furnace professional to take multiple sections of construction and two or three shifts which have greatly increased the potential safety hazards.
4.Special security technology
Blast furnace masonry involves a series of special safety technologies, such as fire prevention, dust prevention, anti-virus, anti-corrosion, anti-fall, anti-object combat, anti-mechanical damage and so on.
QSigns of damage to blast furnace tuyere
Signs of damage to blast furnace tuyere
In the blast furnace production, when the tuyere is damaged, the damage range is not large, and the amount of cooling water in the tuyere leaks into the furnace is not much. If the blast furnace plumber finds the tuyere damage in time and takes appropriate treatment measures, the amount of cooling water leakage into the furnace can be reduced, the control damage range will not be expanded, so it will not bring too much influence to the blast furnace production. It is also easier to replace the tuyere after blowing off. On the contrary, if it is found to be late after damaged, the quantity of water leakage is more, and the damage is enlarged, it will have a direct impact on the blast furnace production, must be causing serious consequences.
The signs of damage to the tuyere can be divided into the following situations:
(1) The tuyere is less damaged. When the tuyere damage is small, there is only a small amount of water marks on the tuyere and there is no “gasp” phenomenon in the outlet when reducing water. The outlet is normal and the working condition of the tuyere is not obviously abnormal. In this case, it is difficult to find the tuyere damage, but if repeated observation and analysis can find the tuyere damage.
(2) The tuyere is damaged greatly. When the tuyere is greatly damaged, by the control of reducing water, the effluent belt "white flower" and even has the intense "gasp" phenomenon, mainly due to the blast furnace gas mixed into the cooling water intermittently from the damaged and reaching the drain.
(3) The tuyere is seriously damaged. When the tuyere is severely damaged, it often occurs a phenomenon that the outlet has little water or even no water.
(4) The tuyere is burnt through. The tuyere burned and exploded suddenly, often because it is not found in time when the tuyere damaged. When the accident happened, there was a hot broken coke from the burning place accompanied by a high-temperature gas injection, and the sound was sharply.
QHow to choose firebricks?
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.The proportion of the standard brick and special 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.
QDistinguish quality of high alumina bricks from color and single weight
Distinguish quality of high alumina bricks from color and single weight
High alumina brick is the most basic refractory brick in refractory products. It is mainly used in industrial furnaces such as iron and steel, steel making, hot blast stove, electric arc furnace roofs, blast furnace, reverberatory furnace and rotary kiln lining. High alumina brick mainly composed of high alumina bauxite, sillimanite minerals; artificial composition of materials, such as industrial alumina, mullite, electric fused corundum and so on.
High alumina bricks have the characteristics of good quality, high refractoriness and long service life. They are the primary refractory brick products used in industrial furnaces. The general unit can not correctly distinguish the quality and grade of high-aluminum bricks at the time of acquisition, resulting in a high price to buy low-grade goods, and then reduce the service life of the kiln, so here is a brief introduction from the color and single weight in the acquisition of high alumina bricks how to identify the quality of bricks.
Color: When purchasing high-alumina bricks, the color is the first priority. The surface of the high-alumina brick is lubricated,the color is yellow and white, the four sides are flat, no break angle, no cracks.
Single weight: To weigh the weight of a single brick, according to the component specification, the first grade high aluminum brick is 4.5 kg, the second grade is 4.2 kg, and the third grade is 3.9 kg, equal grade, equal parameter. Types of equal parameters that can reach this specification can be regarded as excellent high-aluminum bricks. If cracks, uneven corners, and broken corners are found, they are unqualified products.
QMain process of blast furnace refractory products construction
Main process of blast furnace refractory products construction
Refractory masonry and and refractory construction for blast furnace can be divided into 13 main processes from bottom to top.
A. Construction of refractory castables and ramming mass under the bottom of the furnace.
B. The carbon glue at the bottom is pressed in the furnace so that the bottom of the furnace is combined with the ramming mass at the bottom of the furnace.
C. Full-spread leveling layer, carbon material filling, after the filling hole has been completely sealed and welded, the carbon material is transported to the construction site, and the preparation of the center line measurement is completed, the anthrax leveling is performed after the flat steel is divided.
D. Masonry silicon carbide bricks. After the leveling construction is completed and up to the standard, the steel brackets and the supporting sleepers are installed, and then masonry is carried out from the center to the two ends, finally the filler in the reserved expansion joint is filled with tamping of pneumatic pick.
E. Full-filled carbon brick furnace bottom: Use special tools (vacuum chuck) to hoist the carbon bricks in place, according to the angle position specified in the construction drawings of each layer of carbon bricks, under the premise of ensuring safety and precision, adopt 50~70% carbon brick bonding material for masonry.
F. Masonry mixed furnace bottom: The construction is carried out by using the annular carbon brick support seat. After completion of this work, the furnace wall can be built.
G. Masonry hearth carbon bricks under the iron blocks.
H. Masonry tap hole with hearth wall.
I. Masonry hearth wall under the tuyere.
J. Masonry the tuyere with hearth wall.
K. Refractory bricks for furnace bosh and part of the furnace waist.
L. Refractory bricks for furnace body and part of the furnace waist.
M. Complete the construction of castable for furnace throat.
The above 13 parts can be constructed in stages according to different situations. When the furnace shell is designed with refractory brick support, measures can be taken to construct the furnace body section first, then the furnace bottom to the furnace waist section, and parallel water flow can be constructed at the same time.
QHeating method for high temperature industrial furnace
Heating method for high temperature industrial furnace
When refractory products are fired in an industrial furnace, they are necessary to obtain uniform heating as evenly as possible. There are four methods of common heating.
1. Internal heating
According to the nature of the fired product and the structure of the kiln, the fuel is mixed into the material for combustion heating. For example, when burning light refractory materials, sawdust, coke powder and anthracite powder are added to the mud material. Using this way not only the heat is uniform, but also the burning of the combustible material causes the product to have a certain porosity.
Because the hot air flow has a tendency to rise upwards, it is easy to cause uneven temperature distribution in the heating chamber. And the bottom burner is difficult to maintain, the burner coverage is not large, so there are not many applications for bottom combustion.
3. Side heating
It is the most widely used heating method in the silicate industry, such as downdraft kiln, shuttle kiln, tunnel kiln, pool kiln, etc. Due to the large cross-fired surface of the lateral combustion, a relatively uniform temperature distribution can be obtained on the bottom of a larger area of the furnace. In order to avoid the direct erosion of the flame on the material causing coking or over-burning deformation on the material, a flame can be used to align the combustion passage or use a fire wall. In side combustion, as in general tunnel kiln, the kiln should not be too wide due to the limitation of the burner's jet force.
The width of the kiln can be not restricted. The burner is arranged at the top and the number can be unrestricted, so that small flow rate and multi-point dispersion configuration can be adopted to further improve the uniformity of the temperature distribution in the kiln and the heat transfer conditions of the flame gas to the products.