Improvement of boiler top seal and casing insulation
The No. 2 furnace of Junggar Power Plant is Beijing Babcock. Wilcox Co., Ltd. produces 1004t/h, subcritical parameters, intermediate reheat, natural circulation, single-drum boilers. The original design boiler top seal is a thin layer of micro-expansion refractory plastic on the ceiling pipe, and the surface is welded with a metal sealing plate; all the medium in the casing is a drum with a saturated temperature and a near saturation temperature, and a header (water-cooled) Wall and wall), water-cooled wall outlet pipe, saturated steam extraction pipe, according to the steam flow, the first-stage superheater outlet header drawing requires insulation, and the water supply pipe is not insulated. 1 The original design of the top seal structure of the original design of the top seal structure is: (1) all the wall through the pipe is cast 60mm thick refractory plastic. (2) Casting a layer of 48mm thick refractory plastic from the front ceiling entrance header to the front wall junction box. As shown. (3) A refractory plastic with a thickness of 45 mm is cast in the A and C parts of the rear ceiling, and a refractory plastic with a thickness of 16 mm is cast in the B part, as shown. (4) Through the ceiling of the screen type superheater, first and second superheater, reheater and other high temperature areas, 40 mm thick aluminum silicate refractory fiber felt is used to wrap the heated surface outside the top of the furnace, and pass through The layered steel mesh and the outer wire mesh are bundled with a heat insulating material on the pipe. (5) The insulation around the casing is composed of 3 layers of thermal insulation material, the inner layer is 30mm thick aluminum silicate refractory fiber felt, and the outer 2 layers are each 60mm thick composite silicate plate, and the thermal insulation nail is welded on the furnace plate. The outer layer of barbed wire, the insulating nail and the self-locking plate are used to fix the heat insulating material on the guard plate. (6) The top of the cover is insulated by a three-layer structure, and the inner two layers are microporous calcium silicate insulation boards with a thickness of 50 mm. The microporous calcium silicate is fixed on the top plate by using support hooks and pressure plates, and the outer layer can be cast. Ultra-light heat-resistant insulation material integral casting, thickness 2 furnace top seal and casing insulation improvement Through the investigation of the actual operation of the same type of domestic unit, it was found that there was leakage at the top of the furnace and the surface temperature of the casing exceeded the standard. To this end, the following improvements were made to the top seal and casing insulation of No. 2 furnace in Muir Power Plant: (1) In the metal sealing plate of all the top wall-through pipes, the first layer was cast with a 60 mm thick refractory plastic according to the original design. The second layer is coated with a high-temperature adhesive with a thickness of 3 mm; the third layer is affixed with a 20 mm thick aluminum refractory fiber; the fourth layer is fired with a 40 mm thick refractory plastic, and the fifth layer is coated with a high thickness of 3 mm. The agent is finally filled with aluminum silicate loose cotton in the remaining space to prevent dust smoke leakage, as shown. The improvement of the top seal and the cover insulation of the No. 2 furnace is on the metal seal plate. Some special pipes and metal seal plates are not required to be welded. In order to prevent leakage due to thermal expansion during operation, a sealed box is added in this part, and the seal box is constructed during construction. Fully welded with metal sealing plates. As shown. Through the screen part of the screen superheater, the first, second superheater, reheater and other high temperature areas of the insulation layer from 2X20mm thick to 4X20mm, aluminum silicate refractory fiber plus high temperature adhesive paste, the surface of galvanized wire mesh The high temperature material is 20mm thick. As shown. Insulation structure is added in the lower part of the top cover of the shell and the side guard plate, the first layer is welded with insulation hook nails, the second layer is laid with 40mm thick rock wool board, the third layer is coated with 20mm thick aluminum silicate refractory fiber, the fourth layer Lay galvanized barbed wire. 6mmX20mmX20mm, the 5th layer self-locking tablet is pressed and the insulation hook is bent to fix the insulation material. As shown. The improved aluminum silicate refractory fiber in the thermal insulation structure of the microporous calcium silicate and the top of the shell and the top and side shields of the shell at the top of the shell makes the elastic and dense contact between the hard materials of each layer To prevent the hard material from breaking and the contact is not tight during operation, the gap and heat loss are increased. The thickness of the castable ultra-light insulation material is increased from 70mm to 150mm of the original design. A sealing box is added to the root of each boom at the top of the casing, and a sealing structure is arranged inside the box. The first layer is coated with a layer of 50 mm thick aluminum silicate refractory fiber with a high temperature adhesive, and the second layer is fired with a thickness of 50 mm. It can be plastic, the third layer is affixed with a layer of 50mm thick aluminum silicate refractory fiber, and the fourth layer is fired with a refractory plastic with a thickness of 50mm. As shown. The roof of the furnace and the water-cooled wall and the wall of the wall are sealed as shown in the refractory plastic. The insulation around the cover, the original design of aluminum silicate refractory fiber 1 layer thickness 30mm changed to 2 layer thickness 20mm, mainly to prevent the high temperature heat dissipation due to the tightness of the 1 layer of aluminum silicate refractory fiber splicing, resulting in excessive temperature. Other insulation designs are unchanged. As shown. 3 Description during construction (1) Before construction, the construction personnel are familiar with the contents of the technical measures of the drawing and grasping the technical measures, and the technical construction of all construction workers is required, and the construction personnel are required to strictly follow the requirements of technical measures. (2) All insulation materials must have instructions for use, certificate of conformity, and factory inspection report. It is strictly forbidden to use materials that are not qualified. (3) When pouring refractory plastic, clean the dust, debris, grease, etc. on the ceiling of the whole boiler, and fill all the voids on the ceiling with aluminum silicate cotton and high-temperature adhesive, according to the thickness required by the design. Cast refractory plastic. The refractory plastic can be beaten and leveled during construction to ensure the integrity and tightness of the boiler roof. (4) During the construction of aluminum silicate refractory fiber felt, they are mutually staggered, pressed and spliced, and the high-temperature adhesive is applied between the layers. The coating should be uniform and compact. The galvanized wire mesh should be laid flat and close. Insulation layer, the first layer of the surface layer is leveled, and the second layer is laminated and compacted. (5) When the top of the casing is constructed, a 20 mm thick aluminosilicate refractory fiber felt is laid on the cover of the casing, which is laid flat, dense and mutually staggered. When constructing microporous calcium silicate, it is required to be tightly constructed. Metal seals play a key role when the top is sealed. Before the construction, it must be closely coordinated with the boiler and welding site to ensure the construction process is reasonable. At the same time, it must be welded according to the boiler plant design and welding requirements to ensure the welding quality. After the metal sealing plate is welded, it will be inspected and inspected together with the supervision and engineering quality inspectors to achieve the best effect of the boiler top seal. When the top of the furnace is cast into the refractory plastic, two layers of high-temperature adhesive are applied to the pipe to prevent the thermal expansion from causing gaps and leakage. Every construction process should be carefully checked and accepted, and the next process can be carried out after passing the inspection. For special parts, such as the front cross position of the roof of the furnace and the position of the wall through the roof of the furnace, carefully follow the measures and requirements for construction, and do a good job of supervision and inspection. 4 Effect of improved top seal The No. 2 furnace of Junggar Power Plant improved the top seal by using soft insulation materials, increasing insulation thickness and changing the insulation structure. During the operation of the boiler, the top of the boiler was inspected and no leakage was found; when the surface temperature of the casing was tested on site, it was less than the ambient temperature of 25 °C, in compliance with the regulations. The top seal of No. 2 furnace achieved the effect of heat preservation and heat insulation, and achieved the intended purpose. 5 Conclusions 5.1 The cause of boiler roof leakage is related to design, construction and operation. 5.2 Measures to improve the sealing performance of the top of the furnace are: (1) the design is reasonable and feasible; (2) to ensure the construction quality of the roof refractory, thermal insulation seal and metal shield sealing; (3) to maintain the furnace top negative pressure operation. (Editor: Wang Pingzhi) (Finish) Hydrazine Hydrate 35,Hydrazine Hydrate 35%,Hydrazine Hydrate Cas 10217-52-4,Pesticide Raw Material Yibin Tianyuan Group , https://www.ybtyco.com