增压锅炉汽包应力有限元分析.pdf

Y1437173
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UDC:
编号
工学硕士学位论文
曾压锅炉汽包应力有限元分析
硕士研究生;陆永杰
指导教师;宋福元副教授
学位级别:工学硕士
学科、专业;热能工程
所在单位:动力与能源工程学院
论文提交日期:2008年1月18日
论文答辦日期:2008年3月8日
学位授予单位:哈尔滨工程大学
哈尔滨工程大学硕土学位论文
摘要
船用增压锅炉是利用涡轮增压机组的压气机替代汽轮机鼓风机向锅炉炉
膛输送具有一定压力和温度助燃空气的锅炉。汽包是锅炉中重要的受压元
件,它连接上升管与下降管组成自然循环回路,同时接受省煤器来的给水,
还向过热器输送饱和蒸汽,它是加热、蒸发、过热这三个过程的连接点。汽
包运行工况极其复杂,不仅要承受内部较高的压力,还要承受冷、热态启停
及变负荷时的循环机械应力和热应力,这些交变应力很容易产生疲劳破坏。
因此,对锅炉汽包展开应力分析,得出增压锅炉汽包稳态及启动工况下应力
的变化规律,为增压锅炉最优启动方案提供一定的理论支持,理论和实际意
义重大。
运用 ANSYS软件建立了某增压锅炉汽包孔的三维模型,对汽包内压应
力、热应力以及总应力分布进行三维有限元数值模拟分析。模拟得出了
6.5MPa压力下的稳态内压机械应力以及压力从常压增加到6.5MPa时的瞬态
应力,上下汽包壁温差相差52℃和78℃的稳态热应力和从常温增加到两种
温度工况下的瞬态热应力。最后计算出压力以及不同温度共同作用下的稳态
总应力和不同启动方案下的瞬态总应力。得到了汽包的应力集中状况,并根
据应力值和材料特性对汽包进行了强度评定,为汽包的安全运行和设计提供
了依据。
模拟结果表明:此型增压锅炉内压最大应力值是在汽包孔沿轴向截面的
内点(通常所说的A点),跟压力值大小成正比;而热应力值分布相对复
杂,在水汽交接面较大ー点。与上下汽包温差成正比。总应力是内压应力和
热应力的矢量和,在A点总应力值比机械应力小,这说明适当大小的热应
力对内压应力有削弱作用,而在孔区的汽包外壁总应力增大,这说明热应力
对内压应力有叠加的作用。在汽包上下壁温差大于300℃时由于热应力的增
大削弱作用不明显,叠加作用明显,容易出现危险,启动时间越短,应力值
越大。
关键词:增压锅炉;汽包;有限元;应力
哈尔滨工程大学硕士学位论文
Abstract
Marine supercharged boiler uses the compressor of turbocharger unit instead
of blower of turbine to transport air with a certain temperature and pressure to the
furnace of boiler. Drum is the important pressure component in the boiler, which
connects the rise and fall pipes and composes a natural loop, at the same time,
accepts the supply water from the economizer, also transports saturated steam to
the super heater, which is the connection point of heating, evaporation and
overheating. Drum operating conditions are very complicated, not only have to
bear a higher internal pressure, but also endure start-stop when it is cold and warm,
and endure mechanical stress and thermal stress when load changes, which often
leads to fatigue failure. Therefore, develop the analysis of boiler drum, get the
change law when drum starts and runs steadily, which can supply some theoretical
support for the optimal start plan, theoretical and practical significance are great
Found a three-dimensional model for a supercharged boiler drum hole using
ANSYS, make the three-dimensional finite element simulating and analyzing of
the pressure stress, thermal stress and the total stress distribution of drum. Get the
steady-state pressure when it is 6.5 Mpa, as well as the transient stress when the
pressure changes from atmospheric pressure to 6.5 Mpa, the steady-state thermal
stress when the temperature difference between the upper and lower wall of drum
is 52C and 78 C, the transient thermal stress when the temperature varying from
room temperature to the two conditions. Finally, calculate the pressure and the
total steady-state of different temperature and the total transient stress of different
conditions. Drum stress concentration situation is gained, and according to stress
values and material properties make a strength assessment for drum, which
provides evidence for safe operation and design of drum
Simulation results show that the greatest stress of this kind boiler is the
interior point along the axial section of drum hole (which is commonly known as
A), which is proportional to the pressure alue. The thermal stress distribution is
relatively com