船舶辅锅炉装置4技术方案.ppt

我国海运部门尚未制定统一的锅炉用水的水质指标。 1981年交通部颁布的“交通部直属水运船舶锅炉水质标准及 处理规程(试行)”中规定的水质标准如表13—4和表13—5所示。 A. Economizer sectionPreheats the circulating water before it enters the evaporator tubes. B. Evaporator sectionWater evaporates and emulsion of steam and water flows back to the boiler. C. Superheater sectionSuperheats the steam for the turbine. D. Heat exchangerPreheats the boiler feed water. E. CondenserThe exhaust steam from the turbine and excess steam from the steam system condense and recycle. F. Condensate pump G. Cooling water pumpSeawater. H. Make-up water pumpFrom softener unit. I. Boiler feed water pump ? 1.Steam pressure controlThe pressure control loop adjusts the burner load according the steam demand. 2.Water level control A simple control loop will do for a boiler with large amount of water and relatively small steam output. To minimize shrink and swell at start and stop of the burner it would be wise to have two set points for the water level. A lower level (abt. 40%) when the burner is stop and a higher (abt. 50%) when its firing. 3.Economizer inlet temperature control The feed water is pre-heated in order to increase the efficiency of the plant. The circulating water to the exhaust gas boiler heats the feed water and the three-way valve on the inlet to the heat-exchanger controls the temperature. The economizer inlet temperature must never fall below 135°C to avoid corrosion on the economizer tubes. 4.Condenser pressure control An absolute pressure transmitter and a controller adjust the cooling-water to the condenser to protect the condensate from being cooled down more than necessary. 5.Condenser level control The level controller actuates the condensate outlet control valve. 6.Feedwater tank level control The level controller actuates the make up water control valve. 7.Steam dump control valve Takes care of excess steam from the waste heat boiler when the steam production exceeds the steam demand. 1 .废油/废液燃烧器： 废油150...860...kg/h