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Masonry Techniques for Unit Kiln Furnace

The quality of masonry significantly impacts the lifespan of the kiln furnace, fuel consumption, glass melting, and drawing operations. To meet the basic requirements of brick dimensions and thermal expansion for the kiln furnace, the pool wall bricks and pool bottom paving bricks are cut and ground. Additionally, it is crucial to reasonably reserve expansion joints between refractory bricks.

(1) Steel Frame Acceptance and Preliminary Masonry

① Based on the construction baseline and centerline of the kiln furnace, perform the steel structure layout construction. Lay main beams, secondary beams, and flat steel according to the design requirements and allowable construction deviations, also conducting construction for the passageway steel structure.

② To ensure the quality and progress of masonry construction, pre-masonry is required for pool wall bricks, pool bottom paving bricks, and all load-bearing arch bricks that have strict requirements on dimensions and brick joints. However, if the size accuracy of the aforementioned bricks meets the design requirements, pre-masonry may be omitted. Bricks subjected to pre-masonry must be sequentially numbered for proper placement during formal masonry.

(2) Masonry Sequence and Methods

① Upon successful acceptance of the pool bottom steel structure, project the relevant feeding ports, front and rear drum bubbling, and the centerlines of each station for drawing boards on the kiln furnace construction baseline and centerline.

② Masonry of the pool bottom includes the passageway base. After constructing the insulating bricks and high alumina large bricks on the pool bottom, expand the inner and outer sides of the pool wall by 30-50mm for leveling. For multi-layered pool bottom structures, deviations must be controlled according to the baseline, and the allowable deviation of the total thickness of the pool bottom is generally -3mm. A layer of zirconium material is placed on top of the high alumina large bricks on the pool bottom as a sealing layer to prevent glass liquid from penetrating into the corrosion-resistant clay brick layer.

③ Masonry of the pool wall includes the passageway pool wall. The bottom bricks of the wall must ensure horizontal alignment; otherwise, the bottom bricks at that location must be processed until the requirement is met. When masonry involves multiple layers of pool wall bricks, the operation should proceed from the inside to the outside, ensuring the internal dimensions of the furnace chamber and strictly prohibiting bricks from being chiseled facing the furnace chamber. Wall corners should be built with staggered compression joints to maintain verticality strictly.

④ Hoisting of columns. Stabilize the columns temporarily, then install the anchor angle steel according to the design requirements. Columns and anchor angle steel must be closely aligned, ensuring the correct elevation.

⑤ Masonry of the large arch. After making the arch mold, conducting load-bearing settlement tests and corresponding size checks through the arch frame, the large arch is built simultaneously from both sides towards the center. Continuous operation is required, and efforts should be made to complete it within 24 hours. Construction of the large arch insulating layer is carried out after the kiln firing.

⑥ Masonry of breast walls, front walls, rear walls, and flame spaces of the passageway. The masonry of the breast wall should take place after careful inspection of the installation of supports, plates, and brackets. Measures should be taken to prevent the tipping of the hanging brick and breast wall brick.

⑦ Masonry of flue and chimney. Masonry should only be carried out after clearing debris from the kiln and thoroughly cleaning with a vacuum cleaner. The masonry of the melting kiln flue and chimney must also coordinate with the metal heat exchanger, and the passageway chimney must be built after the passageway masonry is completed.

⑧ Two masonry methods: dry masonry and wet masonry.

a. Dry masonry is used for the melting zone and the pool bottom, pool wall, hanging brick in the flame space, the arch brick in the melting zone, and the top cover brick in the passageway.

b. Wet masonry is used for the side walls and arch top in the melting zone flame space, flue, chimney, and the insulation layer bricks of the kiln furnace. The mud used in wet masonry should be prepared according to the corresponding refractory mud based on the refractory bricks used.

(3) Quality Requirements and Inspection of Masonry

① Brick joints require small gaps between bricks. The allowable thickness of brick joints for various spatial positions of the masonry is generally not more than 2mm. The joint thickness of the arch bricks should be less than 1mm, and for insulating bricks, it can be expanded to 3mm.

② Expansion joints: Refractory bricks expand when heated, and expansion joints should be provided based on the temperature conditions of the brick material and the location. The average value of expansion joints left in each 1m-long brick body can be calculated using the average linear expansion coefficient. For pool bottom bricks and pool wall bricks, the expansion joints should be appropriately reduced to prevent inadequate expansion. The average value of expansion joints for dense chrome bricks and dense zircon bricks used in glass unit kilns is approximately 5mm. Expansion joints should be evenly divided (with a spacing not exceeding 2m), left in a closed manner between inner and outer brick layers, and left in an alternating manner between upper and lower brick layers, with the joints kept clean and the outer layer sealed with tape.

③ Allowable tolerances: Strict tolerances are specified for benchmark elevation, horizontal alignment, verticality, line dimensions, and surface flatness of the masonry. The thickness of brick joints is checked using a feeler gauge with the thickness equal to the specified thickness of the joint. Flatness is checked in all directions using a 2m straight edge. After all inspections are completed and the kiln is cleaned multiple times, seal treatment is applied to minimize the entry of external debris and dust into the kiln.

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