Top fired hot blast stove
The construction of refractory materials for top-fired hot blast stoves can be mainly divided into four parts, namely labyrinth masonry, air and gas ring cavity masonry, vault straight section and hot air outlet masonry, and vault masonry. The specific construction points of masonry are as follows:
PART 01 Maze masonry
According to the central elevation of the combustion air pipe, back-calculate the control elevation of the top of the labyrinth. Combined with the relevant dimensions of the drawing, taking into account the actual elevation, levelness and pre-swing size of the brick support plate installation, determine the thickness of the leveling layer of the brick support plate castables, and Lay out the maze brick layer control lines on the spray layer.
Control the size of the probe of each layer of maze bricks into the furnace body. Pay attention to the layering when building the outer and outer ring bricks in the furnace body. Strictly control the size of the sliding joint between the regenerator wall and the labyrinth (30mm), and fill it with refractory ceramic fiber blankets.
PART 02 Air and gas ring cavity masonry
When laying the first layer of bricks in the air annular cavity, dry-swing the bricks along the furnace body to check the seams (to prevent the occurrence of processed bricks), ensure that the brick seams are ≤ 2mm, the furnace body diameter meets the design requirements (6620mm), and use a radius wheel rod to check Check whether the arc and furnace inner diameter are within the allowable range (±15mm). According to the central elevation of the air duct, control the spray layer according to three layers and release the air and gas ring cavity brick layer control lines; the inner and outer ring walls of the air and gas ring cavity must be laid flat, otherwise triangular joints will easily appear in the overhead bricks.
Before building the air and gas pipeline inlets, a stainless steel protective plate with δ=3mm needs to be installed. It consists of two halves and is welded at the installation position. Between the gas ring cavity and the air channel, a layer of δ=0.3mm thick 1Cr18Ni9Ti stainless steel sealing plate is wrapped vertically along the furnace body; on the top brick of the air ring cavity, two layers of δ=0.3mm thick stainless steel sealing plate are laid with staggered joints. The purpose of the 1Cr18Ni9Ti stainless steel sealing plate is to prevent cross-leakage of air and gas from causing explosions. The stainless steel plate also plays a sliding role, so the refractory masonry mortar in this part must be full and have good sealing properties.
When building an annular channel for air and gas annulus, first determine the position of the burner based on the central angle of the combustion chamber and the design elevation, and then place the bricks to adjust the brick joints (1~3mm) so that after the burner nozzle is formed, it can move along the furnace body. Evenly spaced around the circumference of the ring. When building air and gas ring cavities, the inner ring of the ring cavity should be built first, and the verticality, flatness and distance between the ring cavities should be controlled with a ruler, center wheel rod, etc. The adjacent elevation error of the inner and outer ring walls should not exceed 5mm. If the outer ring wall is 5mm further away from the spray coating, fill it with spray coating.
After the burner nozzle is completed, the air and gas channels and the annular cavity must be thoroughly cleaned. After passing the inspection, the burner nozzle must be sealed and protected to prevent damage and debris such as broken bricks from falling in.
PART 03 Construction of straight section of vault and hot air outlet
Based on the central elevation of the hot air outlet, lay out the brick layer line of the straight section of the vault on the spray coating. During masonry, the elevation and levelness of the lower furnace wall of the hot air outlet (manhole) must be strictly controlled. Within 1m around the hot air outlet and manhole, andalusite bricks are built close to the furnace shell, with the help of the central wheel rod and the radius of the pipe. The wheel rod is used to round the manholes and pipes, and is first pre-positioned to check the seams, and then the door is closed smoothly. The elevation, flatness and arc of the furnace body of the straight wall under the arch foot brick must be strictly controlled.
During the construction, the hot air branch pipe masonry must be arranged in advance so as not to affect the progress of the straight wall masonry. First lay the lower semicircular lightweight clay bricks of the hot air branch pipe. After the radius wheel rod is rounded, lay the second layer of lightweight high-aluminum bricks. Leave expansion joints according to the design requirements. The location and size must be correct and used. Andalusite brick pressure joints.
The hot air outlet is built with composite bricks (see Figure 3). The lower straight wall is staggered into the furnace in four consecutive layers, with each layer staggered by 34mm. Then, a lower semicircular center wheel rod is supported to control the radius, and petal bricks, petal bricks, and bricks are laid in sequence. Outer ring bricks and inner ring bricks, the inner ring bricks (working layer), outer ring bricks and petal bricks are laid in sequence in the upper semicircle. Between the hot air branch pipe and the hot air outlet composite brick, after the steel fiber castable is poured into the lower semicircle, the inner ring bricks of the lower semicircle are laid. A 50mm expansion joint is designed between the two ring bricks in the upper semicircle and filled with ceramic fiber blankets. The vault is leveled with rigid fiber castables, and two layers of straight wall bricks are laid on staggered platforms (staggered platform size: 53mm+64mm). The center wheel rod of the furnace body is used to find the circle, and the transition section of the cone is filled with insulation castables. Reality.
PART 04Vault masonry
The elevation and flatness of the straight wall at the bottom of the arch brick must meet the design requirements. After the whole ring of arch foot bricks is dry-swung and inspected, adjust the position of the arch foot bricks and the gap between the mortar joints to ensure that the mortar joints are ≤ 2 mm and meet the inner diameter requirements. The arch foot bricks must be sprayed close to the furnace shell. .
The vault bricks must be laid according to the proportion of brick numbers. The big ends of the bricks must point into the furnace. It is strictly forbidden to lay them upside down. The radial joints between the bricks must point to the center of the furnace body to avoid misalignment or triangular joints; the space between every three inner ring silica bricks , put a 5mm expansion joint wooden plywood, and the silica bricks should be clamped to the expansion joint board for masonry. Since the vault bricks are inclined towards the center of the furnace body ring by ring and shrink upward, the inner radius of each ring of bricks should be based on the inner radius size of the vault elevation provided by the design (usually the inner radius of the lower opening of the brick layer is given), using the center wheel lever to control.
Each brick in the vault is placed at an angle and is easy to slide down. When laying bricks, the consistency of the mortar should be increased. After the mortar is applied to the bricks, wait a few seconds before putting them on the wall. At the same time, use brick hanging hooks to securely hook the silica bricks. Each ring The hook is not allowed to be removed until the door is closed. As the inner diameter of the vault becomes smaller, the density of brick hooks needs to increase, and each of the last few rings of bricks must be firmly hooked with brick hooks.
When building vault cover bricks, it is advisable to support insert-type arch tires under the cover bricks.
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