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<p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt;"><span lang="EN-US"><font face="Times New Roman">48</font></span><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: "Times New Roman"; mso-hansi-font-family: "Times New Roman";">.汽轮机启动时为何排汽温度升高?</span></p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt;"><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: "Times New Roman"; mso-hansi-font-family: "Times New Roman";">答:(</span><span lang="EN-US"><font face="Times New Roman">1</font></span><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: "Times New Roman"; mso-hansi-font-family: "Times New Roman";">)汽轮机在启动过程中,调速汽门开启、全周进汽,通过主汽门控制汽轮机冲转、升速,</span><span lang="EN-US"><font face="Times New Roman">2040r/min</font></span><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: "Times New Roman"; mso-hansi-font-family: "Times New Roman";">中速暖机后升速至</span><span lang="EN-US"><font face="Times New Roman">2900r/min</font></span><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: "Times New Roman"; mso-hansi-font-family: "Times New Roman";">,进行阀切换后升速至</span><span lang="EN-US"><font face="Times New Roman">3000r/min</font></span><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: "Times New Roman"; mso-hansi-font-family: "Times New Roman";">。</span></p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt;"><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: "Times New Roman"; mso-hansi-font-family: "Times New Roman";">(</span><span lang="EN-US"><font face="Times New Roman">2</font></span><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: "Times New Roman"; mso-hansi-font-family: "Times New Roman";">)在汽轮机启动过程中,蒸汽经节流后通过喷嘴去推动调速级叶轮,节流后的蒸汽焓值增加(焓降较小),以致作功后排汽温度较高。</span></p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt;"><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: "Times New Roman"; mso-hansi-font-family: "Times New Roman";">(</span><span lang="EN-US"><font face="Times New Roman">3</font></span><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: "Times New Roman"; mso-hansi-font-family: "Times New Roman";">)在并网发电前的整个启动过程中,所耗汽量很少,这时作功主要依靠调节级、乏汽在流向排汽缸的通路中、流量小、流速低、通流截面大,产生了显著的鼓风作用。因鼓风损失较大而使排汽温度升高。在转子转动时,叶片(尤其末几级叶片较长)与蒸汽产生摩擦,也是使排汽温度升高的因素之一。汽轮机启动时真空较低,相对的饱和温度也将升高,即意味着排汽温度升高。</span></p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt;"><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: "Times New Roman"; mso-hansi-font-family: "Times New Roman";">(</span><span lang="EN-US"><font face="Times New Roman">4</font></span><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: "Times New Roman"; mso-hansi-font-family: "Times New Roman";">)当并网发电升负荷后,主蒸汽流量随着负荷的增加而增加,汽轮机逐步进入正常工况,摩擦和鼓风损耗所占的功率份额越来越小。在汽轮机排汽缸真空逐步升高的同时,排汽温度也逐步降低。汽轮机启动时间过长,也可能使排汽温度过高。应按规程要求,控制机组启动时间,将排汽缸限制在限额内。汽轮机排汽温度不允许超过</span><chmetcnv wst="on" tcsc="0" numbertype="1" negative="False" hasspace="False" sourcevalue="120" unitname="℃"><span lang="EN-US"><font face="Times New Roman">120</font></span><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: "Times New Roman"; mso-hansi-font-family: "Times New Roman";">℃</span></chmetcnv><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: "Times New Roman"; mso-hansi-font-family: "Times New Roman";">。</span></p> |
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