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<p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt;"><span lang="EN-US"><font face="Times New Roman">38</font></span><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: "Times New Roman"; mso-hansi-font-family: "Times New Roman";">.所有水位计损坏时为什么要紧急停炉?</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:水位计是运行人员监视锅炉正常运行的重要工具。当所有水位计都损坏时,水位的变化失去监视,正常水位的调整失去依据。由于高温高压锅炉的汽包内储水量有限,机组负荷和汽水损耗在随时变化,失去对水位的监视,就无法控制给水量。当锅炉在额定负荷下,给水量大于或小于正常给水量的</span><span lang="EN-US"><font face="Times New Roman">10</font></span><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: "Times New Roman"; mso-hansi-font-family: "Times New Roman";">%时,一般锅炉几分钟就会造成严重满水或缺水。所以,当所有水位计损坏时为避免对机炉设备的损坏,应立即停炉。</span></p><p class="MsoNormal" style="MARGIN: 0cm 0cm 0pt;"><span lang="EN-US"><font face="Times New Roman">39</font></span><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: "Times New Roman"; mso-hansi-font-family: "Times New Roman";">.电力系统对频率指标是如何规定的?低频运行有何危害?</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:我国系统的额定频率为</span><span lang="EN-US"><font face="Times New Roman">50Hz</font></span><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: "Times New Roman"; mso-hansi-font-family: "Times New Roman";">,其允许偏差对</span><span lang="EN-US"><font face="Times New Roman">3000MW</font></span><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: "Times New Roman"; mso-hansi-font-family: "Times New Roman";">以上的电力系统为±</span><span lang="EN-US"><font face="Times New Roman">0.2Hz</font></span><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: "Times New Roman"; mso-hansi-font-family: "Times New Roman";">,对</span><span lang="EN-US"><font face="Times New Roman">3000MW</font></span><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: "Times New Roman"; mso-hansi-font-family: "Times New Roman";">及以下的电力系统规定为±</span><span lang="EN-US"><font face="Times New Roman">0.5Hz</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";">主要危害有:</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">1</font></span><span style="FONT-FAMILY: 宋体; mso-ascii-font-family: "Times New Roman"; mso-hansi-font-family: "Times New Roman";">)系统长期低频运行时,汽轮机低压级叶片将会因振动加大而产生裂纹,甚至发生断裂事故。</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";">)使厂用电动机的转速相应降低,因而使发电厂内的给水泵、循环水泵、送引风机、磨煤机等辅助设备的出力降低,严重时将影响发电厂出力,使频率进一步下降,引起恶性循环,可能造成发电厂全停的严重后果。</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";">)使所有用户的交流电动机转速按比例下降,使工农业产量和质量不同程度的降低,废品增加,严重时可能造成人身和设备损坏事故。</span></p> |
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