Analysis of metallurgical furnace kiln refractory spray coating construction technology?

Metallurgical furnace kiln, refractory spray coating spray construction has complex operation, high rebound rate, densification and the same series of castables compared to slightly worse and other shortcomings. In the spray coating construction process how to solve the above problems, high quality and efficient completion of the construction task, how to reduce the rebound rate of spray coating, improve the quality of construction, extend the service life of the spray gun head and improve the safety of overhead work, etc., has been troubled by the construction unit of the technical problems. After years of construction practice and technical summarization and refinement, the relevant technical personnel have summarized a set of unique spraying construction methods by adopting new materials to make the spray gun head, and choosing different diameters and lengths of spray guns when spraying different sprayed surfaces, which have been successfully applied in many projects, and have achieved good social and economic benefits.

1. Spraying construction technology and principles

The principle and core part of the spraying construction technology lies in the laboratory before the construction of the project according to the different formulations (generally add 4% -7% water wetting, the muzzle of the control of the water-cement ratio of 10% or so), the material is thrown by hand to the half-meter-square steel plate with anchoring nails, a simple judgment of the bonding effect, the test to determine the mix in the additives. Proportion. And in the actual construction of each operation team from one direction to another direction around the spring type (range of 0.4m or so) to advance forward spraying, until the spray layer to reach the specified thickness shall not be interrupted, and control of the spray gun and the workpiece being sprayed between the surface (0.8-1.2m) the optimal distance between the thickness of the spray layer to accurately control the spray layer, to improve the density of the spray layer and adhesion to reduce the rebound rate of the spray paint to reduce material losses caused by repair and so on. Reduce the material loss caused by trimming.

In terms of spraying equipment, the spray gun head is made of interchangeable, the material is made of thermoplastic elastic rubber with good abrasion resistance and smooth and elastic inner wall (wall thickness δ=10mm). When a large area is sprayed and space is allowed, the gun head with inner diameter Φ35mm and length of about 600mm is used, which is longer than the conventional size and helps to mix the sprayed paint more evenly, improves the stability of the gun head and facilitates the safety, see Fig. 1 for details, and in the case of pipeline and other small spraying operations, the gun head with Φ50mm and length of about 300mm is used, which is strong in dispersion of sprayed paint and should not be piled up, and makes the sprayed paint evenly sprayed, see Fig. 2 for details.

In addition, the wear resistance of thermoplastic elastic rubber material is very strong, which extends the service life of the gun head by about 20% compared with the ordinary steel and rubber material, and the steel one is heavy, which produces a great impact on the gun head when switching on and off the machine, and there is a great safety hazard for the sprayer when operating the gun. Rubber material abrasion resistance is not as good as thermoplastic elastic rubber material, especially easy to cause pipe blockage. Therefore, the choice of thermoplastic elastic rubber material material is the best choice for both safety and construction quality.

2. process and operation

2.1 process

2.2 operation

Spraying operations to ensure the quality of spray coating and resilience has an important impact, according to the order of adding water (or solution) and the amount of water is divided into different wet, semi-dry and dry method of the three. Wet method is the first spray paint mixed into concrete slurry and then spraying operations, semi-dry method is the first spray paint with a small amount of water to wet, sent to the nozzle and then add the remaining water (or solution), dry method of water consumption (or solution) all in the nozzle to join, a comprehensive comparison of the semi-dry method of construction of the lowest rate of rebound is also the most commonly used construction methods, the following focus on semi-dry method of construction points.

2.2.1 construction preparation

1, spraying construction operations, should be on-site construction, testing, machinery, management and other positions of the staff for pre-job training and assessment, without training or assessment of unqualified personnel shall not enter the construction site, and at the same time, should be carried out a comprehensive technical safety briefing.

2, before the construction of spraying construction machinery must be comprehensive cleaning, inspection, commissioning, calibration, and test run normal.

3, before the construction of all machinery must be set up to operate, maintenance and repair, must be equipped with adequate lighting and good communication facilities.

4, before the start should be sent to the wind, while opening the main control valve to check all the air ducts, discharge elbow and the wind package on the pressure gauge connector and so on whether the air leakage. Adjust the friction plate screws, so that the friction plate and friction disk between the air leakage until.

2.2.2 Selection of spray coating equipment

In order to spray the smooth progress of the work, before spraying to do a good job in the selection of construction equipment, debugging and preparation.

1, light, heavy spraying operations when the choice of spraying equipment, including: vortex slurry concrete mixer (350L), belt machine (some are also equipped with reciprocating vibrating screen), rotary vane sprayer, electric air compressor (12m3/min), air bags, electric multi-stage centrifugal water pumps and a variety of pipelines.

2, refractory ceramic fiber (or slag cotton) spraying operations of the spraying station equipment includes: sprayer, electric air compressor (12m3/min), pressure pump, extrusion pump, spray gun and a variety of pipelines.

3, such as the use of wind motor sprayer, before construction should be body parts including supply bowl, distribution disk, vibration shear, sealing ring and friction plate disassembly inspection. Found that the wear and tear exceeds the allowable range, it should be replaced in a timely manner, and then resumed when the installation should be refueled and lubricated, the first boot operation, and then slowly open the air valve, the input of compressed air in order to check whether the sealing parts of the seal.

4, the use of electric motor sprayer, before construction should be checked: the material hole of the hole and the rotating body of the small hole material hole installation position is staggered 180 °, at the same time require that no debris fall into; change the location of the card and the amount of spraying to adapt to the card at the same time should be installed to the card board flat, not tilted; the rotating body, friction disc and the friction plate of the three contact surfaces between the body and the discharge of the elbow of the material is clean. After the above work is completed, it should also check whether the parts connection and pipeline joints are tightened. Next, ventilation inspection should be carried out.

5, the spraying construction of the host parts of the inspection and ventilation checks to confirm that the machinery is intact, all the machinery of the spraying line to organize linkage test run, after passing the operation of the start of test spraying.

2.2.3 Spraying operation essentials

1, spraying surface pretreatment before spraying, need to be sprayed parts should be blown with compressed air to clean the surface of the residue and dust, and then use a steel brush to sweep clean, in order to ensure the quality of spraying.

2. Check all the preparatory work, including the safety of the workplace and the use of equipment, and confirm the readiness of the sprayer operator to get in touch with the sprayer operator to start feeding materials and water.

3, spraying operation of each spraying line for a work shift, spray gun operated by 2-3 people alternately, continuous spraying, from one end to the other end of the spring-loaded forward until the spray layer reaches the specified thickness, without interruption, in order to avoid the production of seams, interlayers and drums and other quality problems.

4, spray coating ratio determination

In the mixing process to control the amount of water in the range of 4% to 7% of the spray coating for wetting, to ensure that the ratio of water and materials, and add the appropriate amount of binding agent mix (binding agent such as: water glass, etc.), is the key to the quality of the construction of spraying. Can be used to grab a handful of mixture in the hand, after the release, the mixture of just not scattered as appropriate, the operator can also be adjusted according to the construction of the water valve at the end of the spray gun, choose the appropriate water ratio, to ensure that the density and quality of the spray coating.

5, different forms of sprayed surface, using different operating methods.

For straight walls and cylindrical parts of the spraying operation should generally be carried out from top to bottom, the pipe surface should be the first half-circle after the upper half-circle spraying, shaped construction surface should be the first difficult to easy, first after the lower, (such as the pipe diameter is less than 1750mm, is not suitable for mechanical spraying, should be used in the support mold casting or manual work methods into).

6, spraying should be carried out continuously in sections, a spray to the design thickness.

If the liner is thicker and needs to be sprayed in layers, it should be sprayed before the first layer of spray paint condensation of the second layer. The rebound material attached to the supporting parts or the bottom of the pipe should be removed in time. But for the acid-resistant spray coating, to be strictly layered, after each layer of spraying to be an interval of time, to be acid-resistant spray coating condensation, in the second and third layer of spraying.

7, composite lining spray, first spray a one-time insulation layer, to come up after the strength, and then a one-time spray refractory layer, generally 3-5h interval, depending on the ambient temperature and strength to determine. Otherwise, the density of the insulation material is small, a one-time spray composite lining, heavy material is easy to bring off the light material, resulting in a large area off, a waste of materials.

8, construction interruption, it is appropriate to make the hew straight hew, in order to facilitate the connection of new and old materials. Repeat spraying, should be in the hew, spray water wetting.

9, spraying layer thickness control

Spraying layer thickness control in the anchorage is buried after all, spraying paint bit to the beginning of condensation, with Φ2 mm metal probe inserted into the construction surface after spraying to determine the thickness, or each square meter welding a and thickness of the same length of a straight bar steel wire to determine the thickness of spraying paint, check in time for refurbishment, if necessary, can be fine-tuning of the material layer, but shall not wipe the surface. If necessary, the material layer can be refined, but shall not be smoothed on its surface.

3. Benefit analysis

Through the use of a smooth inner wall, with high wear-resistant adjustable thermoplastic elastic rubber material spray gun head, the choice of different diameters and lengths of the spray gun head spraying different sprayed surfaces, and to take around the spring type of spraying to the required thickness of the operation, and scientific control of the spray gun head and the sprayed surface of the vertical distance. To ensure the construction quality, shorten the construction period, reduce the spray coating rebound loss rate, reduce the repair loss, improve the safety of the system, save the construction cost, increase the company's revenue, with good economic and social benefits.

The method and the traditional method of construction material loss rate comparison is as follows:

4. Conclusion

This construction technology can be applied to the metallurgical furnace and kiln unshaped refractory construction needs to be fast, low-cost, installation of molds is more difficult, the need to further reduce the cost of construction, space is narrow, irregular or complex shape, thin parts of the lining, as well as need to insulate the protection of space structure and some other special projects. Space structure and some other special projects such as lining construction. By constantly summarizing the improvement of spraying construction technology, not only has the theoretical significance, but also for improving the quality of spraying construction, construction cost savings play an important economic significance.

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