求烘炉方案？ Method for boiler drying： （1）The furnace doors, manholes and air ducts must be opened to let in the natural air for ventilation for several days. Then the firewood shall be piled up in the center of the grate and the firewood can be then ignited for boiler drying. For the first day, no raging fire is allowed for drying the boiler. The wood fire must be stably and evenly burnt to avoid excessively high temperature at the earlier stage of the boiler drying to prevent excessively fast evaporation of the moisture, because that will cause unnecessary pressure, resulting in furnace wall cracks or protruding bricks. （2）During the boiler drying, the firewood shall be placed on the grates. When the air temperature in combustion chamber rises to a certain degree, and the induced air is increased, the damper shall be closed to leave only 1/6 sectional area of the air duct opened. For the first two days, the damper shall be opened at this fixed position. The firewood can be added in through the manholes in the combustion chamber or ash hopper to maintain the stability of combustion。 （3）The firewood must be stably and uniformly distributed, and adding firewood should not be done at the end of the firewood burning-out. The moist firewood shall be mixed with the dry wood for the burning. After the first day of drying, the fire shall cover half of the grate area and is close to the center of the grate. After the slow heating up for two days, the temperature of water in the boiler water wall tubing or steam drum shall not be higher than 70℃. The fire shall not be placed underneath the front and rear arches to avoid fast temperature rise in the front and rear arches （4）When the drying goes to its third day, a small quantity of coal shall be added into the fire to gradually substitute the firewood. At this time, the grate shall be started. When the fire is burnt with the coal, the flue gas damper shall be properly opened to 1/3 of the sectional area. The water in the boiler shall be in this time heated up to nearly boiling point. （5）Boiler drying work should be continued to the extension such that the furnace wall temperature reaches the following criteria： a． Where there is no water wall, the temperature in the wall between internal refractory bricks and external red bricks or diatomite bricks shall reach 200℃. b． From the outer red-brick to further 100mm, the temperature shall reach up to 50 ℃ After the above temperature is reached, the drying will continue at this condition for over 24 hours more (thermometer should be installed in the furnace wall before drying starts, and symmetrically placed in the center of the height direction of the two sides of the water wall so that they may be referenced to each other). Besides the above-mentioned drying method, steam drying method can be used, namely steam is used to heat up the water, so as to gradually raise the wall temperature for drying purpose. Or, direct steam heating may be applied to drying up the furnace wall but the drying duration may be properly extended . 0.3~0.4MPa pressure saturated steam shall be led into the furnace continuously through the blowdown valve of the water wall headers to gradually heat up the boiler water and keep the normal water level. The boiler water temperature generally is controlled to around 90°C. The flame shall be the main heating source when the progress is ongoing to the end of the process. The total drying duration shall not be less than 10 days. 4. It is better to often inspect the boiler walls and properly control the temperature to prevent cracks, and deformation defects of bumps or dents.。 5. When the boiler drying is ended, the boiling out might be commenced. The alkaline boiling out may rely on the following list for dosing. The purity is expressed in percentage in the list. When trisodium phosphate is in shortage, sodium carbonate may be used as a substitute, but the dosing shall be increased as 1.5 times that of trisodium phosphate. If only sodium carbonate is used for the boiling out, the dosing for each m³ of water shall be 6kg. Chemical name Dose kg/m³(water) For thinner scaling For thicker scaling Sodium hydroxide（NaOH） Trisodium phosphate（Na3PO4•12H2O） 2—3 2—3 3—4 3—4 6. The chemicals for the boiling out should be dissolved into liquid before poured into the boiler. The boiler at this time shall be kept at low water level to prevent the chemical liquid from entering the superheaters. 7. At the end of the boiling out, the steam pressure should be raised to 75% of the boiler working pressure in order to improve the boiling-out effect. The boiling out shall continue for 2 ~ 3 days, during which, the samples shall be regularly taken from the steam drum and the lower header of the water wall for analysis. When the boiler water alkalinity is below 45 mg/liter, complement dosing shall be required. 8. After boiling out is ended, the boiler shall be shut down and drained out. The boiler steam drum and lower header of the water wall shall be inspected and the deposits and residues shall be completely cleaned off. The valve that have been used for boiling out in contact with the chemicals shall be flushed out. The blow-down valve shall be checked for plugging. After boiling out, the steam drum, headers internals shall be free of oily matters and the metal surfaces shall be free of rust after the debris and foreign material are wiped out. 9. Steam tightness test shall be carried out after the boiler drying and boiling out are conformable. The process shall comply with the following procedure： a. The flanges, manholes, hand hole and other bolts for connection parts within the scope of the boiler shall be tied up once more under hot conditions when the boiler is heated up and reaches 0.3 ~ 0.4 MPa in pressure. b. When the pressure is raised to the working pressure, manholes, flanges and connection parts shall be checked for tightness and conditions of the steam drum, header, tubing circuits and supports for the thermal expansion shall also be checked. 10. For the relief valve, the initiating pressure shall be set and adjusted, and the pressure gauge reading for the relief valve installed at the safe place shall be prevailing. a. The initiating pressure for one of the steam drum safety valves shall be adjusted for the setting of 4.47MPa and the other shall be for 4.56 MPa. b. The safety valve on the header of the superheater outlet shall be set at 3.97 MPa. c. The relief valve recoil pressure is slightly less than the working pressure where the relief valve is installed. d. The relief valve should have no steam leak and shock. 11. The boiler superheater should be blown off with the steam. During the blow off, the superheater outlet header vent shall be opened to the atmosphere to maintain the approximately 75% of the boiler working pressure (i.e. drum pressure is about 3.2 MPa), while the proper steam flow shall be maintained and the blow off time shall not be less than 15 minutes 12. After the foregoing work is completed and acceptable, the boiler shall be subject to a 72 hours continuous test running, for the purpose of the performance test. 13. The required conditions for the test running： a. The defects previously discovered shall be corrected and repaired. b. New boiler auxiliary machinery, subsidiary system and fuel, feed water and auxiliary power system can satisfy the boiler’s demand for full load. c. The inspection and test work have been completely finished d. The I&C devices, electric instrument and controls necessary for the test running shall have been in stalled, adjusted and calibrated according to design requirements for installation adjustment. e. The operation organization shall be well prepared to satisfy the long term full load demand of the boiler during the test running. 14. During 72 hours test running, all the auxiliary equipment should be put into operation simultaneously or in succession, the boiler proper, auxiliary machinery and equipments shall work normally, and their expansion, tightness and bearing temperature of rotating shafts and spindles as well as the vibration should all generally meet the technical requirements, steam parameters, combustion conditions and so on.查看更多2个回答 . 5人已关注
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