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Refractory material and masonry method for dry-process cemen

Date:2019-04-28 11:32     writer:admin     Views:

  Since both the cyclone preheater and the decomposition furnace are stationary equipment and mainly bear the friction of the powdery material, the strength requirement of the refractory lining can be correspondingly reduced. Generally, the lining material is used, that is, the refractory material which has a certain degree of refractoriness, alkali resistance and can resist the powder and high temperature airflow is used as the working layer, and the heat insulating material with low thermal conductivity is used as the heat insulating layer.

  There are many types of refractory products used in cyclone preheaters and decomposing furnaces, especially cone hoppers of various levels of cyclone cylinders, which have different cone angles, resulting in a large number of similar appearances, and refractory bricks with little difference in color are applied to the preheater. And decomposition furnace system. Attention should be paid to the nuances of materials and shapes, which are selected one by one according to the design.

  In principle straight bricks and anchor bricks are used for straight walls, wedge-shaped wedge bricks are used for cylindrical surfaces only in one direction, and wedge-shaped bricks with taper in both directions are used for the laying of tapered hoppers. The pouring material is generally used for a straight wall with a large area which is easy to collapse, a flat roof surface and a complicated shape, and a refractory brick is used to lay a part which is easy to fall off. The heat insulation board and the heat insulation block are used between the high temperature refractory brick or the pouring material and the steel casing as the heat insulating stuffing material. Because it is a two-layer insulation material, the masonry should be laid out in principle, but it is difficult to implement in practice. In the case of refractory bricks of silicon cover plates, the gap between the two layers of material and the gap between the two layers of material must be filled and filled with binder and refractory mud. For refractory bricks or refractory castables, expansion joints shall be provided, and straight through joints shall be avoided to effectively protect the refractory fiber materials packed therein.

  From the perspective of process layout, the cyclone preheater and the decomposition furnace are from top to bottom, and the temperature is increased by a certain gradient. In addition to the large changes in the adaptation temperature of the refractory products, the anchors of the refractory bricks are also different. The highest temperature is at the decomposition furnace and the kiln exhaust chamber. The heat-resistant steel grade of the anchor should be no less than Gr25Ni20, and the upper preheater anchor can be 1Gr18Ni9Ti.

  The cyclone preheater and the decomposition furnace have convex portions, such as the inlet of the preheater and the joint of the decomposition furnace and the mixing chamber, which is less supported and belongs to the weak link in the masonry. Generally, refractory castables are used for masonry. According to the principle of control joints, the control joints should be properly set at the 200mm part of the highest point of the bulge, and the distribution density of the shank on both sides of the control joint should be appropriately increased. In particular, the distribution density of the dowels in the raised portion.

  Pouring of the smoke chamber

  The pouring of the pouring material can be carried out after all the instruments, the corresponding embedding parts of the cleaning holes and the inlet end of the barrel of the air gun are fixed. If necessary, temporarily remove 2 to 3 fan-shaped plates from the kiln tailing cone to provide sufficient space for the frame pouring at the seal of the smoke chamber to be restored after the completion of the masonry. The large-area straight wall of the smoke chamber, whether it is made of refractory brick or refractory castable, should consider the proper setting of the expansion joint and the brick. Straight walls should be built with the feed opening of the blanking pipe to ensure its integrity and high overall strength. After the completion of this part of the masonry, the masonry of the roof of the smoke chamber can be carried out, and the main point is to refer to the masonry of the top plate of the grate cooler.

  When the laying of the tongue is carried out, the pouring material at the feeding end should be poured once and the surface should be smoothly entered into the kiln. The ridges connected by the template should not be left to ensure smooth material flow. For individual parts, it is allowed to use the hole filling operation and the grinding with a portable grinding wheel, but it is not allowed to carry out the repair of the large area, which is equivalent to the secondary pouring. For longer feed ends, expansion joints should be left when the refractory cast material is poured.

  Since the feed end is a cantilever structure, the joint with the smoke chamber will be subjected to a large bending moment. The pouring material needs to be smooth and smooth, and the weight of the pouring material should be controlled. Excessive weighting of the tongue, due to excessive increase in deflection under high temperature conditions, may cause undue friction with the refractory material of the kiln cylinder. In severe cases, it can cause damage to the refractory material and even cause damage to the equipment.

  Lining of air gun barrel pre-buried

  The inserted gun tube must be inserted all the way to the surface of the lining template and the barrel is welded to the housing. If the pipe is inserted into the lining material as a pour material, a section of the pipe around the pipe may be free of insulation to ensure the overall strength of the refractory material in the cell. The nail should be welded and a certain thickness of cardboard or calcium silicate board should be used to seal the opening of the barrel to avoid the pouring of the pouring material into the barrel during the pouring process, which is difficult to clean. The surface of the barrel and the nail is coated with asphalt paint to reserve the expansion space. After the template is supported, the pouring operation can be performed.

  The burying of the piezometer and the temperature measuring tube should also be carried out with reference to this principle.

  Bottom cone fabric bucket and shrinkage lining pouring

  The bottom hopper and the shrinkage of the cyclone preheater and the decomposition furnace are the areas where the distribution of the piezometer tube is relatively concentrated; it is also easier to block the shed and the area where the purge tube is concentrated. The following points should be noted when casting it:

  1. Before masonry, technical and instrumentation professionals should be organized to conduct a comprehensive inspection of each hole and buried pipe to see if there is any omission, whether the installation is reliable, and whether the pipe grade is consistent with the design. Whether the installation position and angle are consistent with the design, whether the head of the purge pipe has reliable sealing measures, all the metal materials of the deep castable must be coated with asphalt paint to leave room for expansion.

  2. Conical hopper is prone to accumulation. Once the accumulation occurs, the raw material with relatively low melting point has a small area of ​​foot on the surface of the cone, which will be based on the area where the accumulation occurs. The 'enclosure' eventually led to blockage of the hopper. Therefore, it is necessary to ensure the smoothness of the cone surface of the hopper.

  3. Conical hoppers usually use refractory bricks and castable materials to lay the upper and lower parts respectively. For refractory brick masonry, each refractory brick of the cone hopper has a suitable ratio of up and down, inside and outside. If it is necessary to build the ideal cone, each layer of refractory brick needs a specific size. This is unacceptable economically and administratively. In actual work, the outer dimensions of the refractory bricks are usually calculated according to the two upper and lower layers of the bricks, and the middle and uppermost layers of the refractory bricks are both The brick-like type is put together in a way that roughly approximates a conical surface with a roughly flat circumference. On the cone surface, it consists of a cone-shaped cone with a small taper that forms a substantially complete large cone cone. Therefore, the situation of not coplanar between the bricks must be controlled. At the time of masonry, it should be noted that the connection between the layers does not allow the occurrence of the bosses that cause the accumulation. For this reason, if the smooth connection between the layers is not made during the masonry, the refractory bricks and the brick joints should be adjusted to allow the lower bricks to retreat relative to the upper brick truncated countertops, but the lower layers are never allowed. The bulge of the brick.

  4 .For the part with castable, the formwork should be carefully installed and the thickness of the cast space reserved for injection molding should be checked. The connection of the template should be tight to prevent the leakage from causing the void; the support of the template should be strong, the template misalignment and bulging should not be allowed to occur, and the surface of the cone fabric should be broken. Apply a layer of paraffin or grease to the stencil, or directly cover a layer of polyethylene film to facilitate the subsequent demoulding and smoothing of the castable surface. After pouring the castable, the upper surface of the castable should be adjusted perpendicular to the baffle and checked for height to facilitate subsequent masonry of the upper refractory brick. The template is removed after the castable is solidified. While removing the formwork, check that the surface of the castable is smooth. If there are small holes, fill with the castable. If there is a bump, it should be carefully removed and polished when the strength can be carried out to ensure the smooth surface. The transition between the castable and the refractory brick should also be smooth and should not have any protrusions. If there is a situation of non-coplanarity between the two, the method of modification is as follows. For the barrel of the air cannon and the pressure measuring and temperature measuring tube, the anti-blocking material should be carefully cleaned.

  Lining casting of rising pipe

  In addition to a straight wall with a large area, the riser pipe should consider the necessary, sufficient anchor bricks and properly arranged bricks and expansion joints to prevent the straight wall from bulging and collapsing.

  The preheater and the decomposition furnace are mostly round, and a pipe is arranged in the middle of the upper top cover. Therefore, except for the arrangement of the expansion joints of the top cover, the control joints are arranged in a radioactive manner along the center of the circle to the outer circle, and the entire top cover is divided into a plurality of sector-shaped cells. The pouring hole is cut on the top cover, and the degree of coverage of the pouring hole for the pouring of the concrete should be considered.

  Because the preheater and the decomposition furnace are different from the cold, it works in the semi-open state of the kiln frame and works under high vacuum conditions. Therefore, the cut pouring cap should be preserved, and the cementing should be resealed after the drying operation is completed. Prevent the leakage of wind and rainwater from the pouring material hole, reduce the thermal efficiency and increase the fan load.For the rest of the pouring matters, refer to the grate cooler pouring method.

  Masonry of the cutting pipe lining

  From the second-stage preheater and its unloading pipe, there is a castable of about 100 mm inside. Due to the slenderness of the blanking pipe, it is difficult to cast all of the one-time. It is usually divided into segment segment castings of no more than 2.0 m. After the mold release, the docking is carried out.

  In order to ensure that the pipe that is segmented and poured can be assembled correctly, the whole batch of the empty pouring pipe should be decomposed and then several sections of the successful pouring should be decomposed. When decomposing, there should be clear, non-destructive docking marks. Each segment shall be placed on the preheater operating platform or placed on the floor for pouring operations. When pouring, it is very important to ensure that the inner surface of the lining is smooth, the pipe hole concentricity and the thickness of the lining are kept throughout the length of the pipe. This ensures that there is no boss and stagger at the joint of each section after installation. .

  When laying the concrete, the pipe should be flat facing down and placed on the flat steel plate coated with organic oil to ensure the flatness of the joint of the castable. It should be ensured that the inner mold is installed in a concentric and fixed manner with the pipeline. Avoid misalignment of the internal mold during the casting process. The inner mold is coated with a layer of oil or a layer of asphalt paper to facilitate the removal of the inner mold and ensure the smoothness of the inner hole. In order to avoid the occurrence of the boss, a chamfer of 30 x 45° should be provided at the upper interface of the segmented pipe.

  Chamfer reserved when the blanking pipe is docked

  The flap valve of the unloading pipe, usually the supplier has already built the castable, and can be installed directly. If it is not masonry, it can be handled according to the general masonry principle. The working temperature of the fourth and fifth grade flaps is relatively high, and the refractory castables used should be one grade higher than the other flaps.

  Masonry of coal injection pipe

  Since the coal injection pipe is in a high temperature and high temperature grinding condition of the clinker particles, the nail of the coal injection pipe should be made of heat-resistant steel of the high grade of Gr25Ni20, and welded by the corresponding stainless steel welding rod. The dowel should be coated with asphalt not less than 0.2 mm. The refractory castables shall be masonry with high strength and low cement castables with corundum as aggregate. Since the pouring space of the coal injection pipe is small, casting and vibrating are difficult, and the amount of water to be stirred should be avoided. The water reducing agent can be considered.

  After the coal injection pipe is completed, it should be cured to 70% strength to demould. After the demoulding, the curing should be continued, and the drying time should be kept as long as possible (20 ° C ~ 30 ° C), not less than one day.

  Masonry of tertiary duct

  The three air ducts have two forms, parallel and V-shaped. Because of the different wind speeds required by the two, the choice of refractory materials and masonry are also different. The masonry of the tertiary air duct is relatively simple. After the slab of calcium silicate is pasted, the straight pipe is made according to the requirements of refractory brick masonry, and the turning of the duct is mostly made of refractory castable.

  For parallel ducts, refractory materials with high wear resistance should be selected due to the high wind speed required. Especially for the elbow part, the castable with high particle strength (aggregate) and binder strength after drying at 110 °C should be selected. The temperature here does not exceed 1000 ° C, and it is meaningless to select a castable with a greatly increased strength after burning at 1000 ° C.

  For the V-shaped duct, there is a large area of ​​straight wall in the settling chamber, and sufficient anchor bricks should be arranged or refractory castables should be used for masonry.

  For the adjustment valve of the tertiary air duct 1m before and after, it is also the easy wear of the tertiary air duct, and the brick block should be set to facilitate the partial replacement of the refractory brick in this part.

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