The construction process of glass melting furnace is generally to build the bottom flue channel and regenerator first, and then lay the glass furnace bottom, side wall and breast wall blocks.

1. Flue channel

 

When laying the top layer of blocks at the bottom of the flue channel, the blocks should be perpendicular to the direction of the airflow, and the construction should start from the middle of the flue channel and proceed toward both ends. During the construction of the flue channel, an expansion joint of approximately 10 mm should be provided every 3 meters of straight length, with the joints staggered both vertically and horizontally. The masonry around the air exchanger should be inlaid after the installation and inspection of the gate frame.

 

2. Regenerator

 

1)       The outer wall of the regenerator requires staggered bonding between blocks. Adjacent horizontal rows must not have straight joints between clay bricks (insulating bricks) and red bricks. For every 4 to 5 rows, one row should be laid. The outer surface of the wall must be tightly fitted against the I-beam columns.

 

2)       The partition walls of the regenerator must be laid with staggered joints. Expansion joints should be left at both ends of the partition walls, specifically at the door jambs of the regenerator. Clay bricks must be laid using clay mortar, while silica bricks must be laid using silica mortar. Mixing of materials is strictly prohibited.

 

3)       The grates of the regenerator must not be slanted, and their spacing must be strictly maintained with precision. The leveling surface of the grates (leveling plane) must be meticulously leveled. When laying the grates of the regenerator, a centering form must first be set up, and the grates should be measured and adjusted using a template. Construction may proceed only after the alignment matches the template. The centerlines of the grate arch feet must lie on the same straight line.

 

4)       When constructing the arch of each port and regenerator door, a centering form must first be installed and the alignment verified using a grate template. Construction may proceed only after the alignment meets the template specifications. The arch foot blocks and the semicircular arch blocks between them should be laid first, followed by the construction of the door arch. The lock block of the door arch should protrude 30 mm above the arch crown. After driving it into place, grouting treatment must be performed.

 

5)       The error between the actual center line and the designed center line of each port and regenerator should not exceed 5mm.

 

6)       Before laying the semicircular arch, a trial arrangement must be conducted both horizontally and vertically to check for compliance and determine the size of the mortar joints. During arch construction, a brushing mortar method shall be adopted. Each brick must be tightly placed and struck with a wooden hammer to ensure close bonding. After each row of bricks is laid, a leveling board shall be used to ensure evenness. The arch shall be built simultaneously on both sides to prevent displacement of the centering form. The connection areas between the semicircular arch and the door arch or the load-bearing transverse arch of the burner must be pre-processed, pre-assembled, and numbered. During construction, the bricks shall be laid according to their numbers. The lock bricks of the semicircular arch should protrude 50–80 mm above the arch crown. The lock bricks on the same arch must have the same angle and be driven in simultaneously with a wooden hammer, followed by grouting treatment.

 

7)       The transverse arches of the port should be laid in a circular manner, with the lock blocks protruding 50 mm above the arch crown. They should be driven in together using a wooden hammer, followed by grouting treatment. The port can only be constructed after the tie rods of the regenerator columns are tightened and the arch blocks are separated from the arch centering.

 

8)       The chimney blocks must be laid vertically and horizontally, with the centerline error of each flue not exceeding 5 mm, the flue size error not exceeding 6 mm, and the surface levelness error of the chimney blocks not exceeding 8 mm. Leveling chimney blocks by padding materials such as asbestos is strictly prohibited.

 

9)       The cleaning holes in the sealing wall of the regenerator must be aligned with each longitudinal flue and sealed with plug blocks.

 

10)  When building the regenerator wall, clay bricks must be laid between the glass furnace bar skewbacks, the semicircular arch, and the reinforcing iron pieces of the outer wall.

 

3. Port

 

1)      The centerlines of each port on the port should be laid out according to the design-specified benchmarks, with an error not exceeding 5mm. The centerlines of each pair of ports must coincide with each other, and the error should not exceed 10mm. The centerline of the port must be strictly perpendicular to the centerline of the glass furnace tank.

 

2)      During construction, the cross-sectional dimensions must be precise, and the four corners of the port structure should be neat and regular to facilitate the installation of steel structures.

 

3)      A 30mm expansion joint shall be reserved between the bottom of the glass furnace neck and the front wall of the port. During construction, it should be tightly padded with straw rope, which shall be removed after the masonry is completed.

 

4)      All arches of the port shall be constructed by mortar brushing.

 

5)      When laying the locking blocks for the port arch, the supporting angle iron at both arch abutments must be firmly fixed.

 

4. Bottom

 

1)      Large clay bricks for the bottom of the glass melting furnace must be dry-laid. They should be pre-selected, processed, and numbered. Clay bricks that produce a dull sound or cracking noise when tapped, those with cracks or cavities, as well as large clay bricks with edge defects exceeding approximately 30mm on the outer side or greater than 10mm on the inner side are not permitted for use.

 

2)      Large clay bricks for the glass melting furnace bottom must be processed on all surfaces except the one in contact with the molten glass. The machined surfaces of the bricks shall be inspected using straightedges and square rulers, and the gap between the ruler and the brick surface shall not exceed 1 mm.

 

3)      The bottom bricks of each section shall be laid from the centerline towards both sides. The brick joints must be staggered from the flat steel on the glass furnace bottom. The bricks shall be laid in straight and parallel rows, both vertically and horizontally. Expansion joints shall be reserved between bricks, and the top of each joint shall be tightly filled with approximately 50mm thick cardboard to prevent debris or glass from entering.

 

4)      The blocks on the bottom of the glass furnace must be leveled, especially the upper surface of the bottom of the glass furnace where the sidewall is built must be measured and leveled to ensure that the entire glass furnace is strictly level.

 

5. Sidewall

 

1)      Each block of fused cast AZS refractory blocks for the sidewall should be weighed individually. Blocks with higher density should be used in high-temperature, highly erosive areas of the melting tank, as well as in the doghouse and the inlet corners of the throat.

 

2)      The corners of the sidewall should be laid in straight seams, with staggered joints strictly prohibited. The straight seams should be parallel to the longer sections of the sidewall.

 

3)      The sidewall must be straight and even. The casting ports of mullite or fused cast AZS blocks must face the interior of the tank. Block joints should be tightly fitted, staggered vertically, and must not form continuous seams. Gaps should not exceed 5 mm.

 

4)      The allowable error for the entire top surface elevation of the glass furnace sidewall should not exceed ±10 mm. Additionally, the top surface elevation of the melting tank wall should not be lower than that of the sidewall in front of the throat.

 

5)      After the completion of the masonry for the sidewall, glass furnace bottom, and superstructure in contact with the molten glass, the inner surface of the masonry should be cleaned of debris with a steel brush and blown clean with compressed air.

 

6. Breast Wall

 

1)      When laying the tuckstone blocks and breast wall, measures must be taken to prevent inward tilting toward the glass furnace. While placing the tuckstone blocks, align them using a string line on the cast iron plate, apply a thin layer of mortar, and secure them with wooden wedges against the sidewall. The tuckstone heads should rest on the wooden wedges to ensure the tuckstone block‘s surface remains level and to prevent inward tilting due to instability during the breast wall construction.

 

2)      Tuckstone blocks should be dry-laid, and their top surfaces must be leveled using a spirit level. Leave an expansion gap of 1 to 1.5 mm between each tuckstone block, with the gap tightly filled with kraft paper. Remove the paper after construction, except for tuckstone blocks aligned with I-beam columns, where no expansion gap is left. A 5 mm expansion gap should be maintained between the tuckstone surface of the tuckstone blocks and the cast iron plate.

 

3)      No expansion gap should be left between the upper filler blocks and the main arch. Each block must be firmly tapped into place with a wooden mallet. The rear of the upper filler blocks must be tightly secured. The narrow face in contact with the arch skewback should be sealed with mortar, while the wide face in contact with the arch blocks should have a gap of 3–5 mm.

 

4)      For fused cast AZS blocks in the breast wall, the casting port must face outward.

 

7. Crown of the glass furnace

 

The construction of the main crown is the most critical part. The span of this glass furnace‘s crown is 10,800 mm, and the crown is constructed using 400 mm-thick silica bricks, weighing approximately 312.6 tons. This project employs inserted-style port openings (8 pairs in total), so there is no reverse crown in the main crown.

 

The construction process for the main crown is as follows:

 

Marking the centerline of the main crown-Pre-arranging the crown blocks-Marking the construction control lines and expansion joint control lines for each section-Placing the crown blocks-Laying the crown blocks-Locking the crown blocks-Cleaning and grouting-Tightening the tie rods-Pointing and cleaning

 

1)      After the installation of the pre-arranged crown formwork is fully completed, conduct a thorough inspection and adjustment to ensure that the span, crown height, curvature of the formwork surface, and the elevation of the arch crown all meet the required standards. First, mark the longitudinal centerline and the expansion joint lines for each section of the crown blocks on the crown formwork. Then, proceed with the pre-arrangement of the crown blocks. During pre-arrangement, arrange one ring at each end of every section to determine the size of the mortar joints based on the actual dimensions observed during on-site pre-arrangement. Install pre-fabricated large-curvature dragon bone frames at both the ends of the crown and the expansion joints. These frames should be 20–30 mm higher than the crown blocks to facilitate the stringing process.

 

2)      To ensure the overall aesthetics of the large crown surface and prevent misalignment, parallel control lines are laid every 3 rings based on the thickness of the crown blocks to serve as the reference lines for masonry work. The position of the thermocouple blocks is determined based on the centerline of the No. 1 port. Control points are also marked on the dragon bone frames at both ends of each section, serving as the reference for string alignment on the surface of each ring of crown blocks. After the layout work is completed, approximately 1/5 of the total blocks required for the entire large crown are placed on the crown formwork to observe its load-bearing capacity. If no abnormalities such as sinking are detected, the masonry construction of the large crown can commence.

 

3)      The masonry work of the large crown is typically divided into 5–7 sections, with each section ranging from 5 to 8 meters in length. To ensure the overall quality of the crowned structure, the masonry work should be completed within a relatively short time-frame, ensuring that the locking blocks are in place before the mortar dries. The number of workers should not be excessive; Generally, 6 skilled technicians are assigned per section. During construction, the masonry should be carried out symmetrically. Each row of crown blocks is laid simultaneously from both ends toward the center, maintaining consistent progress. Three technicians work on each side of a section, laying blocks longitudinally per ring, with strings guiding the work from both ends toward the center. If block cutting is required, the cut blocks should be placed at the center, specifically aligned with the central column of the section. Vertical rings must be staggered, and no cut block should be smaller than 130 mm. During laying, the orientation of the blocks (larger and smaller ends) must not be reversed. Each block should be laid with mortar, ensuring both horizontal and vertical joint mortar fullness exceeds 95%. Adjustments are made using rubber or wooden mallets. After each ring is completed, a template is used to check the block angles, and a 4,000 mm aluminum straightedge is used to verify flatness. After 20 rings are laid on both sides, the remaining rings are pre-arranged again. If no changes are needed, construction continues. When 15 rings remain in the center, another pre-arrangement is conducted, and adjustments are made if variations are detected. The final three rings are laid alternately and simultaneously, leaving one ring for locking. The locking block ring should be positioned slightly off-center to facilitate the placement of thermocouple blocks. The protruding height of the locking blocks should ideally be between 100 and 120 mm. Locking blocks for the entire section are driven in uniformly after the section is completed. When driving locking blocks, a wooden plank must be placed on the crown blocks to prevent direct contact with the large wooden hammer.

 

Henan SNR Refractory Co., Ltd. is dedicated to the manufacture, research and development of fused cast AZS refractory blocks and bonded refractory materials for the glass industry. Meanwhile, SNR can provide total solutions and services for glass furnace design, glass furnace construction, renovation, and upgrading. Please contact me if you have any requirements.

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