连续蒸汽吹管技术的研究

【作者】 刘浩；

【导师】 潘继红；

【作者基本信息】 山东大学 ， 动力工程， 2006， 硕士

【摘要】 蒸汽吹管是新建机组投运前的重要工序，其目的是为了清除蒸汽管道中的各种杂物，防止汽机通流部分损伤。在母管制机组和超临界机组吹管工作中，吹管方法一般采用稳压吹管方法，该方法运行工况稳定，能保证锅炉稳定运行，但也存在一些不足，如持续时间不长、需要停炉冷却12小时以上、蒸汽消耗量大以及吹管系数计算不够精确等。本课题的研究目的就是延长稳压吹管持续时间，即连续吹管直至该管路吹管完成，同时提高吹管效果。 本课题通过可压缩蒸汽流动原理分析，基于吹管过程中，流动特性是绝热、存在摩擦、可压缩的、节流流动过程，建立了设计计算和吹管系数计算数学模型，采用焓熵图表，计算机编程用于确定管路吹管最有效的蒸汽工况。设计计算可较好地预测吹管工况，吹管时的蒸汽参数应能保证管道承受的动压力至少高于最大运行工况动压力的20％(CFR=1.2)。采用直接测取吹管流量和蒸汽比容的方法来计算动量比，吹管系数计算更精确。 本课题对稳压吹管技术进行了如下改进：采用节流孔板来替代临时控制门；用低压、接近音速蒸汽对蒸汽系统管道进行吹管，可降低临时管道压力等级；采用热力循环工艺，蒸汽管道热力循环是通过在吹扫流程的入口注入锅炉低压给水来实现的，蒸汽温度从最大过热温度降到仅高于饱和温度，温度降低越多，每个管道锈皮剥落就越有效果，省去停炉冷却过程，可以极大地缩短吹管进度；在临时管入口和消音器安装减温器并接入冷却水，可降低临时管温度，降低噪音低于80db；目前稳压吹管一般需要50％以上的额定流量，汽动给水泵也需要投入，采用提高蒸汽比容的方法，较低的蒸汽流量，可得到较高的吹管系数。 本课题的研究已在广东南海石化汽电联产项目蒸汽吹管工作中成功实施。通过对连续吹管设计阶段和吹管现场实施阶段的技术、费用和安全方面的详细分析，极大提高了吹管过程的效率，降低了项目费用，提出的多台锅炉吹管方案节省了大量的临时管道支出，缩短了吹管工期。同时对吹管实施过程中存在的主要问题，如临时管道布置，辅助汽源压力不足，凝汽器补水量不足，锅炉再热器超温及热力循环效果等，有针对性的进行试验研究，进行定性或定量分析，提出了改进及完善方案。更多还原

【Abstract】 Steam blows are used prior to initial turbine powering for steam power plants to clear debris and surface scale that could potentially damage turbine blades during plant operation. Normally, stable pressure method is applied for super critical units and common header units. The method can maintain boiler running stable, but has some deficiency, such as short duration, 12 hours cooling intervals, large steam consumption and simple clean force ratio calculation method. The paper discusses how to lengthen the steam blowing duration, namely continuous steam blowing as far as this pipeline blowing is completed, simultaneously enhances the blowing effect.During the steam blow, the nature of the flow is adiabatic, compressible with friction and choked. The paper provides the model of design calculation and field calculation. Steam analysis is the use of steam table, computer programs are used to determine the most efficient conditions for cleaning steam system piping. Typically, the boiler pressures during steam blow provide a dynamic pressure throughout the piping, which is at least 20% higher than would be experienced for all plant operating conditions (CFR=1.2). By using of actual steam flow and volume, the calculation method of clean force ratio is more precise.The method has some improvements than present stable pressure method. The low-pressure continuous steam blowing method does not use any type of blowing or throttling valve to control the flow of steam. Steam flow for each cleaning circuit will be controlled by strategically placed orifice plates. Effectiveness and duration of blowing processes depends upon the ability to "thermal cycle" the system piping from maximum更多还原