[转帖]节流孔板压差的计算

 
<p class="MsoNormal"><span lang="EN-US" style="COLOR: black"><a href="http://www.bjzyhs.com/jlkb.asp"><span style="mso-field-code: ' HYPERLINK="HYPERLINK"  'http://www.bjzyhs.com/jlkb.asp''"><span style="mso-field-code: ' HYPERLINK="HYPERLINK"  'http://www.bjzyhs.com/jlkb.asp''"><span lang="EN-US" style="COLOR: black; FONT-FAMILY: 宋体; TEXT-DECORAtiON: none; mso-ascii-font-family: 'Times New="New"  Roman'; text-underline: none; mso-hansi-font-family: 'Times New="New"  Roman'"><span lang="EN-US">节流孔板</span></span></span></span></a></span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">压差的计算</span><span lang="EN-US" style="COLOR: black"><?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><o:p></o:p></span></p>
<p class="MsoNormal"><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">　　为了计算</span><span lang="EN-US" style="COLOR: black"><a href="http://www.bjzyhs.com/jlkb.asp"><span lang="EN-US" style="COLOR: black; FONT-FAMILY: 宋体; TEXT-DECORATION: none; mso-ascii-font-family: 'Times New="New"  Roman'; text-underline: none; mso-hansi-font-family: 'Times New="New"  Roman'"><span lang="EN-US">节流孔板</span></span></a></span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">的压差，需引入一个新的概念——阻塞流压差Δ</span><span lang="EN-US" style="COLOR: black">ps</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">。当孔板两端的压差Δ</span><span lang="EN-US" style="COLOR: black">p</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">增加时，流量</span><span lang="EN-US" style="COLOR: black">qm</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">也增加，当压差Δ</span><span lang="EN-US" style="COLOR: black">p</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">增大到一定值时，缩口处的压力</span><span lang="EN-US" style="COLOR: black">pvc</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">下降到流体饱和蒸气压力</span><span lang="EN-US" style="COLOR: black">pv</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">以下，一部分流体汽化，管道流量不再随压差增加而增加，即形成所谓阻塞流现象。此时，孔板两端的压差称为阻塞流压差Δ</span><span lang="EN-US" style="COLOR: black">ps</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">。当</span><span lang="EN-US" style="COLOR: black"><a href="http://www.bjzyhs.com/jlkb.asp"><span lang="EN-US" style="COLOR: black; FONT-FAMILY: 宋体; TEXT-DECORATION: none; mso-ascii-font-family: 'Times New="New"  Roman'; text-underline: none; mso-hansi-font-family: 'Times New="New"  Roman'"><span lang="EN-US">节流孔板</span></span></a></span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">的实际压差Δ</span><span lang="EN-US" style="COLOR: black">p</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">小于其对应的Δ</span><span lang="EN-US" style="COLOR: black">ps</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">时，就可避免闪蒸或汽蚀的发生。当管道两端压差较大时，可采用多级减压，但每一级</span><span lang="EN-US" style="COLOR: black"><a href="http://www.bjzyhs.com/jlkb.asp"><span lang="EN-US" style="COLOR: black; FONT-FAMILY: 宋体; TEXT-DECORATION: none; mso-ascii-font-family: 'Times New="New"  Roman'; text-underline: none; mso-hansi-font-family: 'Times New="New"  Roman'"><span lang="EN-US">节流孔板</span></span></a></span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">的实际压差Δ</span><span lang="EN-US" style="COLOR: black">p</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">均应小于本级入口对应的Δ</span><span lang="EN-US" style="COLOR: black">ps</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">。</span><span lang="EN-US" style="COLOR: black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">　　根据文献</span><span lang="EN-US" style="COLOR: black">[1&gt;</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">，多级节流孔板的的压降按几何级数递减，当第</span><span lang="EN-US" style="COLOR: black">1</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">级</span><span lang="EN-US" style="COLOR: black"><a href="http://www.bjzyhs.com/jlkb.asp"><span lang="EN-US" style="COLOR: black; FONT-FAMILY: 宋体; TEXT-DECORATION: none; mso-ascii-font-family: 'Times New="New"  Roman'; text-underline: none; mso-hansi-font-family: 'Times New="New"  Roman'"><span lang="EN-US">节流孔板</span></span></a></span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">实际压降为Δ</span><span lang="EN-US" style="COLOR: black">p1</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">时，第</span><span lang="EN-US" style="COLOR: black">2</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">级孔板减压至Δ</span><span lang="EN-US" style="COLOR: black">p1/2</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">，第</span><span lang="EN-US" style="COLOR: black">3</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">级孔板减压至Δ</span><span lang="EN-US" style="COLOR: black">p1/22</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">，第</span><span lang="EN-US" style="COLOR: black">4</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">级孔板减压至Δ</span><span lang="EN-US" style="COLOR: black">p1/23</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">，……，第</span><span lang="EN-US" style="COLOR: black">n+1</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">级孔板减压至Δ</span><span lang="EN-US" style="COLOR: black">p1/2n</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">，直减到末级孔板后压力接近所需压力为止。</span><span lang="EN-US" style="COLOR: black"><o:p></o:p></span></p>
<p class="MsoNormal" style="TEXT-INDENT: 21pt"><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">以台山电厂凝补泵再循环管为例，在机组运行过程中，发现管道振动大。分析原因为：凝补泵在正常运行时，出口压力约</span><span lang="EN-US" style="COLOR: black">1.5 MPa</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">，补给水箱进口处的压力约</span><span lang="EN-US" style="COLOR: black">0.12 MPa</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">，当泵出口的除盐水经再循环管回流至补给水箱时，由于压差较大，且管道上只装了一个电动闸阀而非调节阀，因此引起振动。为了减少振动，在第一次设计变更中，采用增加</span><span lang="EN-US" style="COLOR: black"><a href="http://www.bjzyhs.com/jlkb.asp"><span lang="EN-US" style="COLOR: black; FONT-FAMILY: 宋体; TEXT-DECORATION: none; mso-ascii-font-family: 'Times New="New"  Roman'; text-underline: none; mso-hansi-font-family: 'Times New="New"  Roman'"><span lang="EN-US">节流孔板</span></span></a></span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">的方式，实际运行后，泵出口的管道振动有所改善，但</span><span lang="EN-US" style="COLOR: black"><a href="http://www.bjzyhs.com/jlkb.asp"><span lang="EN-US" style="COLOR: black; FONT-FAMILY: 宋体; TEXT-DECORATION: none; mso-ascii-font-family: 'Times New="New"  Roman'; text-underline: none; mso-hansi-font-family: 'Times New="New"  Roman'"><span lang="EN-US">节流孔板</span></span></a></span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">后的管道出现汽蚀现象。说明靠增加</span><span lang="EN-US" style="COLOR: black"><a href="http://www.bjzyhs.com/jlkb.asp"><span lang="EN-US" style="COLOR: black; FONT-FAMILY: 宋体; TEXT-DECORATION: none; mso-ascii-font-family: 'Times New="New"  Roman'; text-underline: none; mso-hansi-font-family: 'Times New="New"  Roman'"><span lang="EN-US">节流孔板</span></span></a></span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">来进行降压的思路是对的，但孔板的选择应有所调整。</span><span lang="EN-US" style="COLOR: black"><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="COLOR: black; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'"></span><span lang="EN-US" style="COLOR: black; mso-bidi-font-size: 10.5pt"><o:p></o:p></span></p><span lang="EN-US" style="COLOR: black"><o:p>&nbsp;</o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="COLOR: black">3.1</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">孔板级数的确定</span><span lang="EN-US" style="COLOR: black"> </span></p>
<p class="MsoNormal"><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">　　考虑管道受静压差</span><span lang="EN-US" style="COLOR: black">44.012 kPa</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">的影响，孔板两端最大压差　</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体">?</span><span lang="EN-US" style="COLOR: black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">式（</span><span lang="EN-US" style="COLOR: black">1</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">）至式（</span><span lang="EN-US" style="COLOR: black">3</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">）中：</span><span lang="EN-US" style="COLOR: black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">　　</span><span lang="EN-US" style="COLOR: black">p1</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">——孔板入口压力；</span><span lang="EN-US" style="COLOR: black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">　　</span><span lang="EN-US" style="COLOR: black">pc</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">——热力学临界压力，对于水，</span><span lang="EN-US" style="COLOR: black">pc=22.5 MPa</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">；</span><span lang="EN-US" style="COLOR: black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">　　</span><span lang="EN-US" style="COLOR: black">FL</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">——液体压力恢复系数，暂定为</span><span lang="EN-US" style="COLOR: black">0.9</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">；</span><span lang="EN-US" style="COLOR: black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">　　</span><span lang="EN-US" style="COLOR: black">FF</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">——临界压力比系数。</span><span lang="EN-US" style="COLOR: black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">　　由于</span><span lang="EN-US" style="COLOR: black">p1=1.5 MPa</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">，</span><span lang="EN-US" style="COLOR: black">p2=0.165 MPa</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">，</span><?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-com:office:smarttags" /><st1:chmetcnv w:st="on" unitname="℃" sourcevalue="20" hasspace="True" negative="False" numbertype="1" tcsc="0"><span lang="EN-US" style="COLOR: black">20 </span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">℃</span></st1:chmetcnv><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">时</span><span lang="EN-US" style="COLOR: black">pv=2.338 5 kPa</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">，根据式（</span><span lang="EN-US" style="COLOR: black">1</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">）至式（</span><span lang="EN-US" style="COLOR: black">3</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">），得Δ</span><span lang="EN-US" style="COLOR: black">p=1</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体">?</span><span lang="EN-US" style="COLOR: black">335 MPa</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">，Δ</span><span lang="EN-US" style="COLOR: black">ps=1</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体">?</span><span lang="EN-US" style="COLOR: black">213 MPa</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">。由于Δ</span><span lang="EN-US" style="COLOR: black">p</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">＞Δ</span><span lang="EN-US" style="COLOR: black">ps</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">，且</span><span lang="EN-US" style="COLOR: black">p2</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">＞</span><span lang="EN-US" style="COLOR: black">pv</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">，所以采用</span><span lang="EN-US" style="COLOR: black">1</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">级</span><span lang="EN-US" style="COLOR: black"><a href="http://www.bjzyhs.com/jlkb.asp"><span lang="EN-US" style="COLOR: black; FONT-FAMILY: 宋体; TEXT-DECORATION: none; mso-ascii-font-family: 'Times New="New"  Roman'; text-underline: none; mso-hansi-font-family: 'Times New="New"  Roman'"><span lang="EN-US">节流孔板</span></span></a></span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">将产生汽蚀现象。为了避免汽蚀的发生，至少应装</span><span lang="EN-US" style="COLOR: black">2</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">级</span><span lang="EN-US" style="COLOR: black"><a href="http://www.bjzyhs.com/jlkb.asp"><span lang="EN-US" style="COLOR: black; FONT-FAMILY: 宋体; TEXT-DECORATION: none; mso-ascii-font-family: 'Times New="New"  Roman'; text-underline: none; mso-hansi-font-family: 'Times New="New"  Roman'"><span lang="EN-US">节流孔板</span></span></a></span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">。</span><span lang="EN-US" style="COLOR: black"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="COLOR: black">3.2</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">孔板压降的确定</span><span lang="EN-US" style="COLOR: black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">　　根据前面的分析，当采用</span><span lang="EN-US" style="COLOR: black">1</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">级节流时，孔板压差大于阻塞流压差，采用多级节流降压后，第</span><span lang="EN-US" style="COLOR: black">1</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">级</span><span lang="EN-US" style="COLOR: black"><a href="http://www.bjzyhs.com/jlkb.asp"><span lang="EN-US" style="COLOR: black; FONT-FAMILY: 宋体; TEXT-DECORATION: none; mso-ascii-font-family: 'Times New="New"  Roman'; text-underline: none; mso-hansi-font-family: 'Times New="New"  Roman'"><span lang="EN-US">节流孔板</span></span></a></span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">的实际压差应小于阻塞流压差，其压差的大小取决于第</span><span lang="EN-US" style="COLOR: black">2</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">级孔板，多级</span><span lang="EN-US" style="COLOR: black"><a href="http://www.bjzyhs.com/jlkb.asp"><span lang="EN-US" style="COLOR: black; FONT-FAMILY: 宋体; TEXT-DECORATION: none; mso-ascii-font-family: 'Times New="New"  Roman'; text-underline: none; mso-hansi-font-family: 'Times New="New"  Roman'"><span lang="EN-US">节流孔板</span></span></a></span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">的压降按几何级数递减。因此，若采用</span><span lang="EN-US" style="COLOR: black">2</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">级</span><span lang="EN-US" style="COLOR: black"><a href="http://www.bjzyhs.com/jlkb.asp"><span lang="EN-US" style="COLOR: black; FONT-FAMILY: 宋体; TEXT-DECORATION: none; mso-ascii-font-family: 'Times New="New"  Roman'; text-underline: none; mso-hansi-font-family: 'Times New="New"  Roman'"><span lang="EN-US">节流孔板</span></span></a></span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">，则　　</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体">?</span><span lang="EN-US" style="COLOR: black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">其中Δ</span><span lang="EN-US" style="COLOR: black">p1=0.89 MPa</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">，Δ</span><span lang="EN-US" style="COLOR: black">p2=</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">Δ</span><span lang="EN-US" style="COLOR: black">p1/2=0.445 MPa</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">。</span><span lang="EN-US" style="COLOR: black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">　　为了防止</span><span lang="EN-US" style="COLOR: black"><a href="http://www.bjzyhs.com/jlkb.asp"><span lang="EN-US" style="COLOR: black; FONT-FAMILY: 宋体; TEXT-DECORATION: none; mso-ascii-font-family: 'Times New="New"  Roman'; text-underline: none; mso-hansi-font-family: 'Times New="New"  Roman'"><span lang="EN-US">节流孔板</span></span></a></span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">发生汽蚀，应以阻塞流压差Δ</span><span lang="EN-US" style="COLOR: black">ps</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">为准则，验算各级</span><span lang="EN-US" style="COLOR: black"><a href="http://www.bjzyhs.com/jlkb.asp"><span lang="EN-US" style="COLOR: black; FONT-FAMILY: 宋体; TEXT-DECORATION: none; mso-ascii-font-family: 'Times New="New"  Roman'; text-underline: none; mso-hansi-font-family: 'Times New="New"  Roman'"><span lang="EN-US">节流孔板</span></span></a></span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">压差：第一级孔板的阻塞流压差Δ</span><span lang="EN-US" style="COLOR: black">ps1=1.213 MPa</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">＞Δ</span><span lang="EN-US" style="COLOR: black">p1</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">；第二级孔板的阻塞流压差Δ</span><span lang="EN-US" style="COLOR: black">ps2=0.92</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">×</span><span lang="EN-US" style="COLOR: black">[(1.5</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">－</span><span lang="EN-US" style="COLOR: black">0.89)MPa</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">－</span><span lang="EN-US" style="COLOR: black">0.957</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">×</span><span lang="EN-US" style="COLOR: black">0.002 338 5MPa=0.492 3 MPa</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">＞Δ</span><span lang="EN-US" style="COLOR: black">p2</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">。因此，每级</span><span lang="EN-US" style="COLOR: black"><a href="http://www.bjzyhs.com/jlkb.asp"><span lang="EN-US" style="COLOR: black; FONT-FAMILY: 宋体; TEXT-DECORATION: none; mso-ascii-font-family: 'Times New="New"  Roman'; text-underline: none; mso-hansi-font-family: 'Times New="New"  Roman'"><span lang="EN-US">节流孔板</span></span></a></span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">后都不会出现汽蚀现象，采用</span><span lang="EN-US" style="COLOR: black">2</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">级</span><span lang="EN-US" style="COLOR: black"><a href="http://www.bjzyhs.com/jlkb.asp"><span lang="EN-US" style="COLOR: black; FONT-FAMILY: 宋体; TEXT-DECORATION: none; mso-ascii-font-family: 'Times New="New"  Roman'; text-underline: none; mso-hansi-font-family: 'Times New="New"  Roman'"><span lang="EN-US">节流孔板</span></span></a></span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">是合理的。</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体">?</span><span lang="EN-US" style="COLOR: black"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="COLOR: black">4<a href="http://www.bjzyhs.com/jlkb.asp"><span lang="EN-US" style="COLOR: black; FONT-FAMILY: 宋体; TEXT-DECORATION: none; mso-ascii-font-family: 'Times New="New"  Roman'; text-underline: none; mso-hansi-font-family: 'Times New="New"  Roman'"><span lang="EN-US">节流孔板</span></span></a></span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">孔径的计算</span><span lang="EN-US" style="COLOR: black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">　　根据</span><span lang="EN-US" style="COLOR: black">DL/T 5054</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">—</span><span lang="EN-US" style="COLOR: black">1996</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">《火力发电厂汽水管道设计技术规定》，水管道</span><span lang="EN-US" style="COLOR: black"><a href="http://www.bjzyhs.com/jlkb.asp"><span lang="EN-US" style="COLOR: black; FONT-FAMILY: 宋体; TEXT-DECORATION: none; mso-ascii-font-family: 'Times New="New"  Roman'; text-underline: none; mso-hansi-font-family: 'Times New="New"  Roman'"><span lang="EN-US">节流孔板</span></span></a></span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">孔径可按下式计算：（</span><span lang="EN-US" style="COLOR: black">4</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">）</span><span lang="EN-US" style="COLOR: black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">式中：</span><span lang="EN-US" style="COLOR: black">dk</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">——</span><span lang="EN-US" style="COLOR: black"><a href="http://www.bjzyhs.com/jlkb.asp"><span lang="EN-US" style="COLOR: black; FONT-FAMILY: 宋体; TEXT-DECORATION: none; mso-ascii-font-family: 'Times New="New"  Roman'; text-underline: none; mso-hansi-font-family: 'Times New="New"  Roman'"><span lang="EN-US">节流孔板</span></span></a></span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">的孔径；</span><span lang="EN-US" style="COLOR: black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">　　　ρ——水的密度。</span><span lang="EN-US" style="COLOR: black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">　　仍以台山电厂凝补泵再循环管为例。根据现场的实际运行数据，正常运行时热井的补水量约</span><span lang="EN-US" style="COLOR: black">20 t/h</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">，泵出口压力约</span><span lang="EN-US" style="COLOR: black">1.5 MPa</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">，扣除泵进口压力，扬程约</span><st1:chmetcnv w:st="on" unitname="m" sourcevalue="134" hasspace="True" negative="False" numbertype="1" tcsc="0"><span lang="EN-US" style="COLOR: black">134 m</span></st1:chmetcnv><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">，查性能曲线，对应的流量为</span><span lang="EN-US" style="COLOR: black">136.8 t/h</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">，即经再循环管回流至补给水箱的除盐水量约</span><span lang="EN-US" style="COLOR: black">116 t/h</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">。根据式（</span><span lang="EN-US" style="COLOR: black">4</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">）得：第</span><span lang="EN-US" style="COLOR: black">1</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">级</span><span lang="EN-US" style="COLOR: black"><a href="http://www.bjzyhs.com/jlkb.asp"><span lang="EN-US" style="COLOR: black; FONT-FAMILY: 宋体; TEXT-DECORATION: none; mso-ascii-font-family: 'Times New="New"  Roman'; text-underline: none; mso-hansi-font-family: 'Times New="New"  Roman'"><span lang="EN-US">节流孔板</span></span></a></span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">孔径</span><span lang="EN-US" style="COLOR: black">dk1=<st1:chmetcnv w:st="on" unitname="mm" sourcevalue="40.68" hasspace="True" negative="False" numbertype="1" tcsc="0">40.68 mm</st1:chmetcnv></span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">，取</span><st1:chmetcnv w:st="on" unitname="mm" sourcevalue="40.7" hasspace="True" negative="False" numbertype="1" tcsc="0"><span lang="EN-US" style="COLOR: black">40.7 mm</span></st1:chmetcnv><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">；第</span><span lang="EN-US" style="COLOR: black">2</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">级</span><span lang="EN-US" style="COLOR: black"><a href="http://www.bjzyhs.com/jlkb.asp"><span lang="EN-US" style="COLOR: black; FONT-FAMILY: 宋体; TEXT-DECORATION: none; mso-ascii-font-family: 'Times New="New"  Roman'; text-underline: none; mso-hansi-font-family: 'Times New="New"  Roman'"><span lang="EN-US">节流孔板</span></span></a></span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">孔径</span><span lang="EN-US" style="COLOR: black">dk2=<st1:chmetcnv w:st="on" unitname="mm" sourcevalue="48.37" hasspace="True" negative="False" numbertype="1" tcsc="0">48.37 mm</st1:chmetcnv></span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">，取</span><st1:chmetcnv w:st="on" unitname="mm" sourcevalue="48.5" hasspace="True" negative="False" numbertype="1" tcsc="0"><span lang="EN-US" style="COLOR: black">48.5 mm</span></st1:chmetcnv><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">。</span><span lang="EN-US" style="COLOR: black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">　　在该管道的第一次设计变更时，流量按常规泵的再循环量（最大流量的</span><span lang="EN-US" style="COLOR: black">30%</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">）选取，取</span><span lang="EN-US" style="COLOR: black">60 t/h</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">，且压降没按几何级数递减考虑，两级孔板孔径均为</span><st1:chmetcnv w:st="on" unitname="mm" sourcevalue="33" hasspace="True" negative="False" numbertype="1" tcsc="0"><span lang="EN-US" style="COLOR: black">33 mm</span></st1:chmetcnv><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">。根据实际运行情况，经再循环管回流至补给水箱的除盐水量应约</span><span lang="EN-US" style="COLOR: black">116 t/h</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">，但由于</span><span lang="EN-US" style="COLOR: black"><a href="http://www.bjzyhs.com/jlkb.asp"><span lang="EN-US" style="COLOR: black; FONT-FAMILY: 宋体; TEXT-DECORATION: none; mso-ascii-font-family: 'Times New="New"  Roman'; text-underline: none; mso-hansi-font-family: 'Times New="New"  Roman'"><span lang="EN-US">节流孔板</span></span></a></span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">的限流作用，流经再循环管的水量最大只能是第</span><span lang="EN-US" style="COLOR: black">2</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">级</span><span lang="EN-US" style="COLOR: black"><a href="http://www.bjzyhs.com/jlkb.asp"><span lang="EN-US" style="COLOR: black; FONT-FAMILY: 宋体; TEXT-DECORATION: none; mso-ascii-font-family: 'Times New="New"  Roman'; text-underline: none; mso-hansi-font-family: 'Times New="New"  Roman'"><span lang="EN-US">节流孔板</span></span></a></span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">阻塞流时的流量。因第</span><span lang="EN-US" style="COLOR: black">2</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">级</span><span lang="EN-US" style="COLOR: black"><a href="http://www.bjzyhs.com/jlkb.asp"><span lang="EN-US" style="COLOR: black; FONT-FAMILY: 宋体; TEXT-DECORATION: none; mso-ascii-font-family: 'Times New="New"  Roman'; text-underline: none; mso-hansi-font-family: 'Times New="New"  Roman'"><span lang="EN-US">节流孔板</span></span></a></span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">后的压力大于液体的饱和蒸汽压力，故第</span><span lang="EN-US" style="COLOR: black">2</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">级</span><span lang="EN-US" style="COLOR: black"><a href="http://www.bjzyhs.com/jlkb.asp"><span lang="EN-US" style="COLOR: black; FONT-FAMILY: 宋体; TEXT-DECORATION: none; mso-ascii-font-family: 'Times New="New"  Roman'; text-underline: none; mso-hansi-font-family: 'Times New="New"  Roman'"><span lang="EN-US">节流孔板</span></span></a></span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">后出现汽蚀现象，管道产生较大振动和噪音。</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-bidi-font-family: 宋体">?</span><span lang="EN-US" style="COLOR: black"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="COLOR: black">5</span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">结束语</span><span lang="EN-US" style="COLOR: black"><o:p></o:p></span></p>
<p class="MsoNormal" style="TEXT-INDENT: 21pt"><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">在实际工程应用中，将多级</span><span lang="EN-US" style="COLOR: black"><a href="http://www.bjzyhs.com/jlkb.asp"><span lang="EN-US" style="COLOR: black; FONT-FAMILY: 宋体; TEXT-DECORATION: none; mso-ascii-font-family: 'Times New="New"  Roman'; text-underline: none; mso-hansi-font-family: 'Times New="New"  Roman'"><span lang="EN-US">节流孔板</span></span></a></span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">用于减压系统是切实可行的，为了防止管道发生汽蚀，选择</span><span lang="EN-US" style="COLOR: black"><a href="http://www.bjzyhs.com/jlkb.asp"><span lang="EN-US" style="COLOR: black; FONT-FAMILY: 宋体; TEXT-DECORATION: none; mso-ascii-font-family: 'Times New="New"  Roman'; text-underline: none; mso-hansi-font-family: 'Times New="New"  Roman'"><span lang="EN-US">节流孔板</span></span></a></span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">时，一定要根据管道的实际情况，计算出孔板数量和孔径</span><span lang="EN-US" style="COLOR: black">.<o:p></o:p></span></p>
<p class="MsoNormal" style="TEXT-INDENT: 21pt"><span lang="EN-US" style="COLOR: black"><o:p>&nbsp;</o:p></span></p>
<p class="MsoNormal"><span style="COLOR: black; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">来源：</span><span lang="EN-US" style="COLOR: black; mso-bidi-font-size: 10.5pt"><a href="http://www.bjzyhs.com/"><span lang="EN-US" style="COLOR: black; FONT-FAMILY: 宋体; TEXT-DECORATION: none; mso-ascii-font-family: 'Times New="New"  Roman'; text-underline: none; mso-hansi-font-family: 'Times New="New"  Roman'"><span lang="EN-US">热电阻</span></span></a> <a href="http://www.bjzyhs.com/"><span lang="EN-US" style="COLOR: black; FONT-FAMILY: 宋体; TEXT-DECORATION: none; mso-ascii-font-family: 'Times New="New"  Roman'; text-underline: none; mso-hansi-font-family: 'Times New="New"  Roman'"><span lang="EN-US">热电偶</span></span></a><span style="mso-spacerun: yes">&nbsp; </span><a href="http://www.bjzyhs.com/"><span lang="EN-US" style="COLOR: black; FONT-FAMILY: 宋体; TEXT-DECORATION: none; mso-ascii-font-family: 'Times New="New"  Roman'; text-underline: none; mso-hansi-font-family: 'Times New="New"  Roman'"><span lang="EN-US">温度传感器</span></span><span lang="EN-US" style="COLOR: black; TEXT-DECORATION: none; text-underline: none"><span lang="EN-US"> </span></span></a><a href="http://www.bjzyhs.com/sjswdj.asp"><span lang="EN-US" style="COLOR: black; FONT-FAMILY: 宋体; TEXT-DECORATION: none; mso-ascii-font-family: 'Times New="New"  Roman'; text-underline: none; mso-hansi-font-family: 'Times New="New"  Roman'"><span lang="EN-US">双金属温度计</span></span></a> <a href="http://www.bjzyhs.com/jlkb.asp"><span lang="EN-US" style="COLOR: black; FONT-FAMILY: 宋体; TEXT-DECORATION: none; mso-ascii-font-family: 'Times New="New"  Roman'; text-underline: none; mso-hansi-font-family: 'Times New="New"  Roman'"><span lang="EN-US">节流孔板</span></span></a> </span><span style="COLOR: black; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.5pt; mso-ascii-font-family: 'Times New="New"  Roman'; mso-hansi-font-family: 'Times New="New"  Roman'">专业服务网</span><span lang="EN-US" style="COLOR: black; mso-bidi-font-size: 10.5pt"><o:p></o:p></span></p>