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Alumina calciner application cycle boiling
- Published: 16 May 2009 18:34:43
Aluminum Shandong Branch to improve alumina production process and technical level of equipment, from Germany Lucci company to introduce a capacity of 1600t / d of alumina and automation technology with high levels of circulating fluidized bed roaster boiling. September 1997 ignition oven, put into operation. Then installed a set in November 2001 in the ignition. This set of devices used in refractory lining for the calcium silicate board, light weight castable, refractory castable, refractory brick and refractory fibers and anchoring pieces.
First, alumina and refractories roaster cycle boiling choice
1, alumina cycle boiling composition of alumina roaster roaster for roasting cycle boiling aluminum hydroxide by the conical cyclone, venturi dryer, boiling roaster, feed screw, fluidized cooling machines, Circulating Fluidized Bed, discharge chute, the next pipe and wind pipe and flue components. Equipment basically cylindrical shape, the largest equipment outside diameter 5.8m, height 32m, equipment casings welded steel plate, lined with the use of monolithic refractories, refractory bricks, calcium silicate board and refractory fibers, and has anchorage pieces of the fixed link, the entire device among all devices connected to form a sealed, highly integrated device structures.
2, alumina refractories boiling choice Roaster
The device maximum temperature of about 1100 ℃, the maximum pressure of about 12.5kPa, maximum flow rate of 48.5m / s, roasting time was about 30min, that is, the entire baking process at high speed, high temperature to complete. Treatment because of the greater hardness of the alumina materials, mobility, and on the alumina product quality demanding that any liner impurities are mixed with a direct impact on product performance, therefore, require refractories must meet the following conditions: high temperature, wear-resistant, high strength, good heat stability, strong integrity and tightness.
In the selection of domestically produced alternative refractories should follow three principles: ① to ensure that the selected physical and chemical indicators of various refractories to meet the requirements of the company Lucci; ② to ensure that the selected refractory material has a good construction performance, in particular note are the fire-resistant materials; ③ the selected refractory material must be proven. According to these three principles, as have the domestic strength of more than a dozen manufacturers of refractories site visits, more screening, the final choice of the six refractory plant, with foreign refractories the performance indicators were compared, the selection of domestic refractories and refractory materials Lucci's performance close to, and some performance indicators even more than abroad (see table 1).
Second, alumina refractories roaster cycle boiling Application
Circulation boiling roaster refractories used in the entire device a total of 762t, mainly castables, refractory bricks, calcium silicate boards, aluminum silicate fibers and refractory mud five categories, as well as the fixed anchoring refractory pieces.
1, the working layer of refractories castables Total 351t, for a Venturi cooling cyclone, fluidized bed cooler, all piping, flue and boiling roaster and the lower part of the cone cyclone part for many double-or three-tier.
Firebrick shared 269t, mainly used in boiling roaster, recycling cyclone II, Cyclone II, Venturi, such as dryers and flue.
Roaster boiling process in accordance with the characteristics and different process parameters and working conditions, the working layer of refractories of different types and layers. According to the use of temperature, material properties, all process pipes of light and heavy pouring configuration, major equipment lined the use of insulation + insulation + work firebrick layer configuration, so that better energy-saving refractories.
2, heat insulation refractory castable refractories have light, light heat insulation bricks, calcium silicate boards and fire-resistant fiber.
Castable mainly used in fluidized bed cooler, cooling cyclone, a dryer and Venturi Venturi two dryers and other major equipment at the top and all the pipes and the flue inside.
Insulation brick insulation brick shared 41.76t, mainly used in the fluidized bed cooler, a venturi dryer and secondary cyclone.
Calcium silicate board calcium silicate board shared 97.5m3, has 50mm thick and 30mm thick in two specifications, mainly used in boiling roaster, recycling cyclone, cooling cyclone and a dryer, such as Venturi.Refractory Fiber Refractory Fiber share 2.5t, divided plate, blanket and blanket-type category, mainly used in expansion joints, expansion joints, brackets and into the hole and a variety of technology around the hole.
Anchor anchor pieces are lined with pieces of a key component of its role is to enable the furnace wall lined with a solid combination.
Anchor pieces and temperature distribution, refractory nature, lining thickness, the use of the site and the selection of anchor items and materials related to the shape, there are 15 kinds of types, 40 kinds of specifications, the weight of about 3000kg of anchoring system to the lining pieces of the stress distribution and thermal stressbalance, the extension of lining life, played a vital role.
Three, the effect and problems of
1, the effect of the stove and enlightenment ① refractories used in insulation materials focus on the use of equipment in high-temperature boiling roaster and recycling cyclone on a five-storey refractories are used, four-story thermal insulation materials, insulation works well. Although the internal temperature of the furnace up to 1100 ℃, but the appearance of furnace temperature was only around 70 ℃. All other parts of the two-story or three-insulation materials, so the overall thermal efficiency high stove.
② different equipment, different working conditions, selection of different refractory materials, refractory materials used to make more economical, reasonable, and the selection of refractories for the future have a certain degree of enlightenment.
③ different temperature, different fire-resistant material, different lining thickness, different use of the site, using the shape of anchor items, distribution and different materials.
5 boiling roaster, recycling cyclone II, Cyclone II, such as Venturi dome ring by the use of special-shaped brick masonry, between Central and the Central cluster together, and ensuring the overall performance of spherical dome. Castable construction solved the troubles, the conservation of long hours and difficult to repair after damage to the problem.
2, there are problems in less than 3 years of applications, two internal factors boiling roaster Venturi dryer, furnace flue, etc. Red has shutdown maintenance 4 times, for several reasons.
Secondary structure is irrational Venturi cyclone to the secondary channel high-2.5m, width 1.7m, brick thick only 180mm, and divided into two levels (65mm and 115mm), although the anchor has set pieces, but still unstable, and that is, using less than a year away bricks. When the overhaul was carried out to improve and maintain the same surface area with a high degree of the same shell broadbanding 115mm, firebrick thickening 115mm, changed to 65mm and 230mm insulation brick refractory brick. Changed after the run better.
and expansion of the larger joints of this design firebrick furnace height in the general location of each interval of 3.5m left dropsical 25mm expansion joints, according to China's refractories line changes in the 1450 ℃, insulation 2h, linear shrinkage generally +0 ~ -0.2%, coefficient of thermal expansion of 300 ~ 400 ℃ for 0.1%, so 25mm expansion joints too large. Shutdown when all expansion joints through the outer plate can be seen. Therefore, in accordance with the theoretical requirements, expansion joints stay 7 ~ 8mm.
2 Venturi, secondary cyclone and connecting the firebrick aisle low intensity, non-wearable. Furnace 2 years, the secondary cyclone of firebrick from 115mm thick to wear only partial 20mm, 2 Venturi The firebrick wear only around 70mm connecting aisle firebrick has been replaced twice, here the intensity of the selected blocks only 34MPa, firebrick note here do not meet the technical requirements. In addition airflow velocity, and the erosion of alumina to its strict, should use high-strength wear-resistant bricks, high alumina in the aggregate add wear-resistant aggregate in order to enhance the wear resistance of firebrick. Wear-resistant aggregate such as corundum, tabular alumina, etc. with a high refractoriness, creep of small, high-density, thermal shock stability, good wear resistance, etc., in the high-strength wear-resistant parts of the trial brick, can significantly improve the service life of lining.
Castable too large gap between the construction and circulation boiling roaster cyclone passage between the top three floors castables, insulating castables two layers, a layer of refractory castables, anchorage pieces for the ST-20-21 type, because Construction of the gap is too large, alumina washed through the anchor pieces of construction joints, leading to anchor pieces broken off castables, affecting production. Used measures include enhanced anchoring Welding strength, improve the construction process; to reduce the thickness of insulation castables, aisle ends of all the refractory castable, such as reducing construction joints.
