Selection of refractories used in industrial furnace lining:

Refractory and heat insulation material selection of appropriate lining; reasonable structure,

high quality construction, is to improve the thermal performance of the stove and an important factor to improve the service life of lining.

Industrial furnace firebrick main ingredients commonly used is a mixture of SiO2 and Al2O3, impurities can make bricks softening at high temperature, so the highest use temperature lining often limited in 1350 ℃. High alumina brick such as the use of Al2O3 containing greater than 60%, the maximum temperature can reach 1450 ℃ is lining and magnesia brick, magnesia alumina brick; the temperature can reach 1500 ℃, is the excellent material for alkali resistant, so much for the masonry heater. Zirconium corundum brick is abrasion resistant and capacity scale erosion, suitable for sliding track bricks used for continuous heating furnace. Silicon carbide has high strength and good thermal conductivity at high temperature, suitable for the radiation plate less oxidation or non oxidation heating furnace. The basic component, and Fe2O3 component of not more than 1% anti carburizing bricks to SiO2 and Al2O3 resistance, good performance in reducing atmosphere, is a good material for controlled atmosphere furnace.

With the advent of lightweight and ultra lightweight refractory materials, industrial furnace lining inner to refractory fiber or light refractory brick, because this kind of material with refractory and heat insulation performance, especially with low thermal conductivity, heat capacity of small, good thermal stability etc., can significantly speed up the furnace temperature and improve temperature uniformity, and the effect of energy saving is also very remarkable.

Precast blocks are made of various refractory precast refractory plastic and with different properties into different shapes, or on the site directly rammed lining, can shorten the construction period and enhancing the integrity and sealing furnace.

Heating process of refractory materials

Refractory material during this period of time that from room temperature rise to the highest sintering temperature is called temperature rise period, in order to meet the performance requirements of the product quality, the heating speed as quickly as possible.

In this period must consider the following questions:

1. Considering the product size and charge mode, bulky, wall thickness, complex structure and different thickness of the refractory products were firing, heating rate should be slower, so as to avoid the local temperature difference is too large, the expansion is not caused by deformation or crack.
2. From the firing process products to consider, should pay attention to the following several ways: 

• Such as blank in the gas suction, heating speed is slower. Such as adsorption water volatile, organic binder decomposition, hydroxide decomposition is different degree of aspiration. Therefore, when the heating rate should be slower, the temperature can be found on thermal analysis data.
  
   
• Body composition of the billet are crystal transformation, the heating speed should slow down. If the transformation is an exothermic reaction, you should slow heating, in order to avoid hot mutation caused by refractories cracking; if the endothermic reaction, it may be appropriate to strengthen the heat, stay after finishing the transformation should be slow heating, do not allow the temperature rising speed. The phase transition temperature can also be found in the data of thermal analysis. 
• Liquid phase appearance to be careful when heating, the liquid phase appears to increase the contact between particles, improves the transmission speed of body heat, reduce the temperature gradient, to accelerate the speed of temperature rise. But if the heating speed is too fast, too much local liquid phase, there may be due to the self weight or internal force and the body deformation, collapse.

Measures to solve the refractory brick damage

Analysis of mechanism and causes of damage of refractory bricks, take corresponding countermeasure and measure according to these reasons, eliminate the factors of refractory brick damage, so as to achieve the purpose of extending service life of refractory brick.

Cause of refractory brick physical damage and chemical damage ash and kiln skin erosion thin, mechanical damage and the refractory brick masonry quality. That is to say to extend the service life of refractory bricks in burning zone, in addition to select suitable suppliers, shall be laid a good grasp of building quality,

maintain the skin at the kiln kiln during operation. Measures of is:

1. Grasp the quality of refractory brick masonry.

• Cement ratio and dilute the appropriate thick. Specific detection method is easy to spread the cement shop into the brick, and can not flow. Too thick is not easy to spread too thin, is easy to flow; two is in a brick on the fire clay, pressure on another brick slightly strong kneading, and then lift up the brick body, the brick below belt, that the proper proportion of cement.
• The front of refractory brick to be close to the cylinder. Between the brick and the cylinder body cannot pad fire clay and other debris. In the pool of fireclay brick, in front stretcher rectangular to leave 1-2 cm position does not stand in the cement, upward pressure brick, end close to the cylinder pressure to the fireclay, knead move, make cement covered the face brick, a small amount of excess cement extruded from the bricks and the small end of the big two, brick end matter stick cylinder. Brick joints cannot be greater than 1.5mm. Check brick facet, row not up, wrapping phenomenon.
• The top tight top bar. In half of the circumference of the masonry, with top carry to brick top tight, rotary kiln bricks on the other half of the week, when the top bar must be the top tight. Between the brick and the top bar end to pad body, to avoid damaging the refractory brick. Method to check whether the roof top bar tension is, when the top bar with the rotation of the cylinder to check the cylinder top brick not flagging lock position, if the sagging phenomenon, in the kiln and kiln refractory during the relative displacement caused by mechanical damage to the firebrick.
  

2.   hang up and maintain the good kiln crust. In the hanging and protect the kiln crust, mainly take the following measures

• For kiln operation training and guidance. Before ignition, special arrangements for the time of kiln operation training. Clearly pointed out that in any case, hang up and maintain good kiln crust is mainly the responsibility of kiln. At the same time about operating method under different conditions to them, in the actual operation, according to the kiln to give operation guidance and comments in a timely manner, to carry out technical exchanges between operations, and constantly improve the technological level of operation.
• Coal injection pipe reasonable position, with slightly lower guests’ glasses emblem.
• Improve technology status.
• Proper proportioning solution: the quantity of liquid phase resistance is suitable in 22-24%. Too low is not easy to hang kiln skin, too much can narrow the range of sintering temperature, silicate minerals reduce, not conducive to the operation and improve the quality of clinker.

Failure mechanisms and causes of refractory brick

The damage mechanism of refractory brick is divided into physical damage, chemical damage and mechanical damage. Because each damage can be summarized as follows:

1. physical damage: physical damage mainly refers to the high-temperature damage to the refractory brick, the cause of the damage can be divided into follows:

The intrinsic quality of refractory brick: high temperature resistance of the refractory brick, which is refractory brick refractoriness, refractoriness under load.

The reason of the process: the kiln crust thickness and the firm degree. Refractory brick kiln firing without skin protection, its service life is certainly short. The kiln skin erosion thin can be divided into operational reasons, reasons and technical reasons ingredients.

• operational reasons: the refractory nozzle position, the flame shape and the manipulation. The fire nozzle position bias lining erosion, flame kiln skin, make the skin thin flame kiln corrosion; stocky, scour kiln skin, make skin corrosion damage of refractory brick kiln thin, unstable operation, make the kiln peel off frequently, damage of refractory brick kiln; temperature is too high, the damage of refractory brick kiln crust, damage.
• Ingredients cause: Batching scheme unreasonable, such as the KH value is too high, the amount of liquid phase is too low, not easy to hang kiln skin, also can damage the refractory brick.
• process: mainly kiln mouth before the knot ring, so that timely discharge of materials not in the kiln, the abrasion function make kiln crust thinning damage of refractory brick.
  

2. Chemical damage:

Chemical damage mainly refers to the kiln feed in R2O, etch S fusible substances on the refractory brick and damage of firebrick. But if the kiln skin firm and compact, and to resist easy melt material erosion of refractory brick damage.

3. Mechanical damage:

Mainly refers to the period in the kiln is mechanical damage of refractory brick, brick and kiln relative displacement generated irregular, damage caused by shear stress generated by the firebrick. Phenomenon of kiln is running after a period of time, twisted slit brick. Cause mechanical damage associated with refractory brick size error and quality of masonry.

The latest achievements of refractories development

With technology developing, our refractories industry has made ​​great development, but also promoted the development of refractory materials. Domestic refractory materials has made tremendous development.

Specific features:

1. Instead of using natural bauxite alumina industry, has developed a new type of sub-soil just white.
2. The use of flotation and other measures to produce high purity magnesia;
3. Jiangsu, Heilongjiang, dressing made ​​great achievements;
4. Luoyang Yilong Refractory Co., can produce high-quality bauxite
5. The use of Gollum in Qinghai Salt Lake Brine manufacturing high purity magnesia;
6. The use of light burned magnesia mixed with high-alumina spinel synthetic magnesium shovel;
7. High bauxite increased purity;
8. Xinjiang, Tibet and other processing results achieved unprecedented progress;

During this period, China has introduced from abroad advanced production technology and equipment, but also improves the overall level of China's refractories industry. Owing to the continuous development of refractories, refractory industry that makes our country has made tremendous progress.

Introduction and application of Aluminum silicate fiber tiles

Aluminum silicate fibertiles (ceramic fiber tiles) divided into low temperature ceramic fiber brick and high temperature ceramic fiber brick;

using temperature between 800-1400 degrees. The main raw material for the aluminum silicate fiber cotton, using vacuum suction filtration molding production process, and add silica, aluminum phosphate inorganic binder, whose role is to ensure that the high-temperature strength of the products.

Aluminosilicate refractory fibers have excellent slag resistance and thermal shock resistance. Comparison with magnesium carbon refractories, refractory ceramic fiber has better anti-TiO2 slag alkali corrosion and corrosion. In addition, aluminum silicate fiber tiles also has low thermal conductivity, heat capacity, excellent chemical stability, excellent sound absorption, soft, flexible, easy construction, cutting and processing characteristics.

Aluminosilicate refractory fibers have excellent slag resistance and thermal shock resistance.

Comparison with magnesium carbon refractories, refractory ceramic fiber has better anti-TiO2 corrosion and slag alkali corrosion. In addition, ceramic fiber tiles also has low thermal conductivity, heat capacity, excellent chemical stability, excellent sound absorption, soft, flexible, easy construction, cutting and processing characteristics.

Aluminum silicate fiber tiles are mainly used in the construction of various chemical transformation furnaces and furnace linings, construction safety, convenience, while improving the quality of the lining inside the furnace and conversion work has played a crucial role.