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Construction standard for power plant boiler castables

Words:[Big][Medium][Small] Mobile Page Two-Dimensional Code 2019-05-06     

       Boiler castables are lining materials used in circulating fluidized bed boilers, including high-strength wear-resistant castables, wear-resistant plastics, and other refractory materials. The burning characteristics of the boiler determine the quality of the wear-resistant materials, and the quality of the furnace is one of the key factors related to the long-term, safe and reliable operation of the boiler. Therefore, the materials must be strictly in accordance with the material manufacturer. Use the instructions for reasonable operation.

One: preparation before construction

       (1) Main equipment. Forced mixers, small carts, rubber buckets, trowels, winches, φ25/φ35 portable vibrators, tamping machines, rubber hammers, weighing scales, etc.

       (2) The inner surface of the boiler wall is qualified for rust removal. The blasted wall should be removed from the loose scale and oil. All sand and debris must be cleaned to prevent impurities from being mixed into the castable.

       (3) The anchoring nail retaining position meets the design requirements, and the welding is firm: the embedded metal parts (anchor) and the cast metal surface are evenly coated with a layer of 2mm thick asphalt paint before casting or can not be omitted according to the design requirements.

Two: construction method

2.1 High-strength wear-resistant castables

       (1) Mixing of high-strength wear-resistant castables. a High-strength wear-resistant castables are generally woven bag packaging: composed of a mixture and a binder, and the bonding agent is separately packaged. b After adding high-strength wear-resistant castables (mixtures and binders) to the mixer, dry the mixture for 3min~5inm, then open the package in the mixture and the bag and spread evenly and thoroughly (maintain the same color), then add 5.5 at a time. Clean tap water of %~6.5% (pH=6.5~7.5), stir while adding water, the wet mixing time should not be lower than 5min (time should be fully guaranteed). Water should not be added arbitrarily. It must be weighed with a weighing instrument (special water measuring cup). Strict control of the amount of water added is the minimum. It is an important measure to ensure the material strength and various performance indicators. C High-strength wear-resistant castables must be used up within 30 minutes. If the castables are found to be agglomerated or lose fluidity, they should be disposed of. The castables that have been prepared can not be mixed with water during the construction process.

       (2) Forming construction of high-strength wear-resistant castables. a After adding the mixed high-strength wear-resistant castable to the construction work surface at one time, open the vibrating rod to vibrate to the surface of the high-strength wear-resistant castable without any large bubbles. The joint of the support template is sealed with sealing tape to prevent leakage of slurry. Once there is leakage, it will affect the strength of the castable. b The vibrator inserted into the high-strength wear-resistant castable should be fixed and fixed: the casting should be symmetrical and continuous: the vibrating is applied to the portable vibrating rod for mechanical vibration and manual tanning, and the template surface is vibrated as necessary. The vibration rod movement interval is 200mm, each vibration time is about 30s, and the method of "quick insertion" and "full pumping" is adopted to move slowly until the surface is not filled with bubbles. The vibration time should not be too long, no leakage, over vibration. . When the vibration is completed, the rod should be slowly pulled, otherwise segregation will occur, affecting the material, strength and performance. C It is best to cast to the specified thickness once during construction, and the vibration is completely compact. For thicker parts, a layered construction method should be adopted. When the upper layer of the castable is used, the vibrating rod should touch 1/3 of the layer to be poured below, so that the upper and lower castables are tightly combined. d The support of the wooden blocks supporting the thickness of the castable during construction shall not be allowed to be hanged or left in the form being poured. e High-strength wear-resistant castables that have been transported to the work surface must be used up before they are initially set. High-strength wear-resistant castables that have been initially set are not to be used.

        (3) Maintenance and demoulding of high-strength wear-resistant castables. a After the construction of the castable is completed, the temperature is below 20 °C, the demoulding time shall not be less than 96h, and the mold release shall not be less than 48h above 20°C. b After the castable is wet-cured, it must be subjected to strict heat curing and baking. It can only be put into use after it has been cured by heat and baked.

Three: high strength wear-resistant plastic construction

        (1) Composition and packaging of high-strength wear-resistant plastic. a High-strength wear-resistant plastic with high-alumina bauxite (corundum, mullite, silicon carbide) clinker grade superfine powder combination. It is composed of an aluminum phosphate binder, a coagulant and an admixture. b High-strength wear-resistant plastic powder is packaged in woven bags, and plastic binders are packed in plastic drums. The plastic coagulant has been packaged in small bags, in a woven bag package, and the plastic coagulant is indicated on the bag.

        (2) High-strength wear-resistant plastic mixing. a High-strength wear-resistant plastic group with mixed aggregate and coagulant (1 part per bag), which can be adjusted according to the weather changes and temperature of the site. Packed separately, when mixing, it should be poured into the mixer according to the capacity of the forced mixer and the proportion of the construction schedule. The mixing color is the same. b Add the weighed binder to continue the stirring (add about 2/3 binder when weighed), then add the remaining binder according to the specific construction requirements. Stir well and use. (Stirring time is generally 3min~5min). The addition of the bonding agent must be weighed by a weighing instrument (a plastic measuring cup for the bonding agent), and the minimum amount of the bonding agent is strictly controlled, which is an important measure for ensuring the material strength and various performance indexes. The amount of C binder added is 10% ~ 13% (weight ratio), and the minimum addition amount can be adjusted according to the weather change and temperature in the field. d The stirred material must be used up within 40 minutes. The high-strength wear-resistant plastic that has not been used within 40 minutes is strictly prohibited from adding the binder for the second time. The high-strength wear-resistant plastic after initial setting should be discarded. e Clean the forced mixer after mixing high-strength wear-resistant plastics each time to prevent the bottom material from mixing and affecting the construction quality when the forced mixer is used again.

        (3) Construction of high-strength wear-resistant plastic. a Material temperature of the construction site is controlled between 10 °C and 30 °C, humidity is less than 75%. When the temperature of the construction environment is lower than 10 °C in winter, proper insulation measures should be taken. When the temperature of the construction environment is higher than 30 °C in summer, the temperature should be lowered. Measures, rain-proof construction should have rain-proof measures, and it is strictly forbidden to wash the plastic after the construction. b High-strength wear-resistant plastic construction, laying color strips under the construction site, timely recycling the scattered plastic, to prevent mixing with debris, so as to reuse. d Before the high-strength wear-resistant plastic filler, the supporting material plate can be arranged under the construction part to prevent the high-strength wear-resistant plastic from scattering, and the thickness is measured by the galvanized plate scale to ensure the correctness of the primary filler. After the mixed materials are glued into a group, first use a wooden hammer or a rubber hammer to gently smash the construction site, and then pull out the pallet and the ruler plate for dense beating. First, beat horizontally from below, and superimpose 1/3 hammer per hammer. surface. Then it is beaten from the bottom up to the dense. e High-strength wear-resistant plastics are used to inspect the construction site with a gas-permeable solder (steel needle). The upper part is flattened with a trimming knife, and the flatness is checked with a ruler. It was found that the thickness was not enough, and it was necessary to know the thickness of about 1/3, shaving, refilling, and beating to prevent the material from delaminating during the operation of the boiler. f High-strength wear-resistant plastic surface can be trimmed and then pulled, then puncture the hole vertically with φ 4mm steel needle, which is 1/3 of the construction thickness, and the line spacing and spacing are 150mm~200mm, so that the internal air bubbles escape. g High-strength wear-resistant plastics are strictly prohibited to be mixed with water when it is hard: when surface is applied, it is strictly forbidden to sprinkle water or other dry powder on the surface of the construction. h When constructing inside, the high-strength wear-resistant plastic can be glued into a mass from bottom to top. High-strength wear-resistant plastic on the top or top. The high-strength wear-resistant plastic can be firstly made into a blank on the wooden board, and the blanks should be laid close to the wrong seam, and the densely packed and beaten compacted. The other requirements are the same as above. The plastic expansion joints shall be preset according to the design regulations, and the furnace wall expansion joints shall flow into transverse straight through joints and longitudinally staggered joints. After the whole construction and before the hardening, the expansion joint is cut out with thin flat steel according to the spacing required by the design.

        (4) High-strength wear-resistant plastic curing. During the construction of plastics, the vibration of the constructed body should be avoided as much as possible. After the treatment of the working surface of the lining, the natural maintenance is carried out (the materials in the curing room are strictly prohibited from moisture and water), and the curing temperature is 15 °C~35 °C, in a dry environment. (The relative humidity of air is not more than 70%), and the natural curing period is 5d~7d. The oven can then be dried in accordance with the oven profile.


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