The vulnerable influence of refractory castable in construction

1.    The construction of pouring space is small, the construction personnel usually add more water in the mixing, so that you can make the refractory castable has good mobility, but also increase the refractory lining hole body,

reduces the compactness of the lining of the body, and its strength is reduced: the same, lining of the body vibration imperfect, will shorten the service life of refractory castable.

2.     Lining thickness, pouring a small space, many staple clouds between the die and the burner, pouring and vibrating, vibration bar operation very difficult, operation not skilled or not serious, refractory castable is vibrating imperfect.

3.     After pouring, without adequate maintenance, as the lining of the body low early strength, loose structure, often too late to sintering have damaged; the lining body warms up abruptly, sometimes burst.

4.     Winter construction, the ambient temperature is low the binder (hydration) hydration of incomplete or water, or pouring body cold, would seriously reduce the refractory castable strength or destroy its structure, and affecting the use effect.

Solutions to refractory brick shedding used in boiler

Because the boiler pouring material and refractory material damage loss, seriously affect the safe operation of the unit, and even cause non stop accident unit.

In order to ensure the long-term safe operation of the boiler, take the following measures from the operation of the adjustment

• Ignition methods.

1. The ignition temperature process, control the bed temperature and the outlet of the furnace, cyclone separator leg temperature change rate of not more than 80 ℃ / h.
2. By adjusting the fuel door or throttle back to change the oil amount, strengthen with the wind, to maintain the best air fuel ratio, temperature less than 700 ℃ burner piping.
3.  Maintain a volume greater than the minimum fluidizing air flow rate, gas temperature rise faster, by increasing the rise velocity of two air control flue temperature does not exceed the specified value.
4. Bed temperature at 330 ～ 350 ℃ with coal feeding conditions using dynamic way to coal, while adding one or two times volume control the bed temperature and gas temperature from rising too fast, strict monitoring, control the bed temperature and gas temperature change, and the change trend of monitoring oxygen master advanced quantity control the quantity of coal. When the cyclone separator population temperature changes smoothly, gradually changed to continuous coal, used to add less, more in the way of increasing coal, so as to control the bed temperature of furnace outlet flue gas temperature and avoid large fluctuations, reduced the refractories shedding

•    Furnace measures

1. Boiler shutdown process, control the bed temperature, strict furnace exit flue gas temperature drop speed of not more than 80 ℃ / h.
   
2. Slide stop, bed temperature and steam temperature, steam synchronization downhill, by adding one or two times volume decreased bed temperature, to avoid the high bed temperature shutdown period. When the bed temperature below 550 ℃ and the decreasing speed stop to the coal will be a volume is reduced to the minimum fluidizing air flow rate, the two volume is reduced to the minimum, avoid bed temperature drops too fast.
3. Boiler flameout, bed temperature should stop one or two wind turbines operating in more than 400 ℃, prevent the abrupt cooling, fan ventilation and stop running.
4. Fan stops running 4h, bed temperature below 400 ℃ can start fan cooling.

In the boiler start stop, peak shaving, machine breakdown and unit load rejection, strict control of smoke temperature change rate, thus pouring material and refractory protection is not damaged

High purity refractory castable

As everyone knows, high purity refractory castable is born along with the people to improve the metallurgical materials technology and equipment requirements of high power and large scale,

because of the strict of smelting metal liquid component, the component of fireproof materials must be of high purity. Its main varieties of high purity corundum, chromium corundum, high purity of high purity magnesium chromium corundum castable refractory.

High purity corundum refractory castables are mainly used in large and medium-sized ultra high power electric furnace lid triangle zone and the cover of LF ladle refining etc.. Using white fused corundum, high purity tabular corundum and dense corundum as aggregate, dense corundum, white corundum as powder, adding activated SiO2 powders and α -Al2O3 powder amount, at the same time, the addition of dispersant and water reducing agent, the formula and suitable extruding process can produce a life-time when over the import similar products of high purity corundum castable refractory.

High purity chromium corundum refractory castables

is mainly used to produce porous brick and nozzle etc., are widely used in the steel industry, the social benefit and economic benefit are good. The material is mainly tabular corundum and dense corundum as aggregate, white fused corundum as powder, add appropriate amount of industrial chromium oxide powder, activity of SiO2 and powder amount, to CA-80 cement as binder, and adding water reducing agent and retar-Al2O3 prepared.

High purity magnesium chromium corundum castable refractory was developed on the basis of high purity corundum and magnesia refractory castable. Mainly used in air brick, brick, brick, the outer lining of RH nozzle and ladle slag line position; use the effect is also very good. Add the appropriate Cr2O3 powder in high pure magnesium spinel refractory castable, can form MgO and Mg at high temperature (Al, Cr) 2O3 solid solution, so as to improve the high temperature performance.

Refractory material for ladle

1. The clay brick. A12O3 content in clay brick between 30%-50% in general, low price. Mainly used for permanent ladle lining and ladle bottom.
2. High alumina brick. The content of A12O3 in brick between 50%-80%, mainly used for the working layer of ladle.
   
3. Wax brick. The brick is characterized by high content of SiO2. In general more than 80% than the clay bricks, corrosion resistance and good integrity, and without residue. Commonly used in the ladle wall and the bottom of the bag.
4. Zircon brick. The brick for ladle slag line. Brick in ZrO2 content between 60%-65% in general.
5. Magnesia carbon brick. The brick for ladle slag line, especially suitable for multiple ladle continuous casting. Brick in MgO content in general about 76%, the carbon content in 15%-20%. Its characteristic is on the slag erosion, erosion resistance, spalling resistance.
6. Alumina magnesia castable. The castable for ladle body, which is characterized in that under the action of molten steel, MgO and A12O3 reaction of aluminum ovate spinel castable lining, improve the slag resistance and thermal shock resistance.
7. Alumina magnesia carbon brick. This brick is developed on the basis of ladle castable on the lining, long service life.
8. The unfired brick. The ladle for firing brick materials,
   
   almost all made the corresponding unfired brick. Its characteristic is relatively simple fabrication process, low price. The brick itself has certain mechanical strength and corrosion resistance, easy construction and masonry.

If ladle itself is also used for refining, also can choose MgO-Cr2O3-A12O3 series and MgO-CaO-C series refractory material, mainly has: magnesia chrome brick, magnesia chrome brick, the dolomite brick, the iron runner ramming material, etc.

For ladle lining brick used in content of graphite materials, preferably coated with a layer of oxidation resistant coating on the surface, prevent burning, oxidation lining surface osteoporosis, affect its service life.

Hot air furnace drying、 insulation and cold furnace technology

1.  Drying technology of blast furnace and hot blast stove

At present, various kinds of stove of different types, different kinds of refractory material, and the combustion media of different types are a good way to solve the problem of oven.

2.  Long period of silica brick hot furnace insulation technology

Heat insulation furnace, especially thermal insulation brick stove, hot blast stove is shut down or need to repair in blast furnace. How to keep the brick masonry temperature not lower than 600 ℃, while the exhaust temperature is not higher than 400 ℃. According to the site and equipment maintenance shutdown of length and time, using different methods of thermal insulation. The first uses the combustion and keep the roof temperature, air cooling, and the control of exhaust temperature approach called "burning heating, air cooling heat preservation method". The heat preservation method is an effective measure of silica brick hot furnace insulation. No matter how long the blast furnace shutdown time, this method applies.

3.  Silica brick hot stove cool stove reproduction technology

Cool furnace brick stove: brick has good performance of high temperature and low temperature (600 ℃) instability. In the past, silica brick hot blast stove once put into production, can no longer be cooled to 600 ℃,

otherwise it will suddenly shrink, rupture and collapse of brick masonry. The experimental study of a large number of internal and external, cold furnace brick stove, there are two kinds of methods are: natural slow furnace cooling and rapid cooling furnace.

Silica brick for hot blast stove, natural corrosion cold furnace is successful, but because the relationship between the natural period, slow cooling time, do try to quickly cool furnace. A steel mill blast furnace brick in hot blast stove was fast cooling furnace, with 14 days of the furnace successfully to cool down. And successfully repeated reproduction. Fast cooling furnace is very successful, breaking the "firebrick in hot blast stove life goods" argument, that silica brick hot furnace fast cooling furnace is feasible "indicates the possibility and inevitability of silica brick hot blast stove cross generation".