Construction requirements of wear-resistant and fire-resistant plastic
(1) Before construction, ensure that the laying site is clean. If refractory plastic is used for repair, the adhesive should be applied appropriately.
(2) The material should be vibrated evenly. If the construction site is deep, it should be poured or filled in layers from bottom to top. Each layer should be vibrated and compacted after completion to ensure that there are no hollow parts inside (hollow parts often have serious overheating during operation). After the material is initially solidified, it should be fully knocked with a small hammer or hard object for inspection. If the sound is dull, it is dense and qualified. If the sound is loud and accompanied by a sustained sound, it means that there is a hollow inside. The outer steel plate of the corresponding part should be cut off and the hollow part should be refilled.
(3) If the construction area is small, it is advisable to repair it by manual patching. Before repair, it should be carefully checked whether welding and grabbing are required; if the repair area is large, the castable should be filled. After construction, the surface should be flat and smooth, and the size should meet the requirements of the drawings.
Construction requirements for grab nails and heat-resistant steel bars
Before the construction of wear-resistant and fire-resistant plastics, anchor welding should be carried out first. Our factory mostly uses "Y"-shaped nails and "V"-shaped nails. The lower part of the hanging screen in the furnace, special parts (tube parts, deformation parts and material flow change parts, etc.), severe wear parts, etc. are generally fixed with 6mm "V"-shaped nails in the general configuration, and the material is 1Cr18Ni9Ti or higher. It should be pointed out that the original tube screen generally uses 10mm pins, but in actual maintenance, we found that the pins are easy to fall off during the construction process. The fallen pins will take away the tube wall tissue, causing the tube wall to become deformed or even damaged. In order to reduce risks and improve safety assurance, we basically use the "V"-shaped nail welding method on the fins during the construction process. After a lot of operation practice, it has been shown that this method is safer and more reliable. Before welding, the selection of the gripping nails is strictly prohibited from substitution and misuse, and the spacing is strictly controlled. The spacing of 6mm "V" nails in our factory is generally controlled at 70-100mm, and the spacing of 350mm "Y" nails is generally controlled at 150-200mm.
Baking furnace
1. The maintenance and baking of wear-resistant and refractory plastics directly affect the performance of the boiler during operation. After construction, the material contains a large amount of moisture. During the heating process, steam is continuously precipitated and accumulated. If the steam is precipitated too much and too fast, the material will bulge, crack or even fall off; secondly, if the baking furnace temperature and duration are not enough, residual moisture is likely to exist, and the material will also crack and fall off during operation-therefore, baking of wear-resistant and refractory materials is an important task after the construction is completed.
2. If the repair area is small, a baking gun can be used for baking. The temperature should be properly controlled during the baking process. If the construction period is long, it can also be naturally air-dried. It is usually more than 72h. Before starting the furnace, it is necessary to check whether the wear-resistant and refractory materials have cracks.
3. If a large area of the furnace is to be replaced, a special furnace drying plan should be formulated. The reference process is as follows:
(1) Furnace drying start
a. Start the small flow gun of the ignition air duct burner, first put it into operation with low oil pressure and small oil volume. After it stabilizes, gradually increase the oil supply and strictly follow the temperature rise curve to heat up and keep warm; b. Start the large oil gun of the air duct burner, put it into operation with low oil pressure, small oil volume and low smoke temperature. After the combustion stabilizes, gradually increase the oil volume and strictly follow the temperature rise curve to heat up and keep warm.
(2) Arrangement and quantity
There are 2 oil guns for the ignition air duct, one large (1.2t/h) and one small (0.8t/h). 2 on each side.
(3) Baking curve
a. Raise the temperature to 130±20℃ and keep it constant for 12 hours at a temperature rise rate of ≤20℃/h; b. Raise the temperature to 230±50℃ and keep it constant for 12 hours at a temperature rise rate of ≤20℃/h; c. Cool down at a cooling rate of ≤30℃/hr; d. Open the manhole door to cool down after cooling down to 80℃; e. After the baking is completed, remove the brackets and partitions in the furnace and clean the inside.
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