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1、专业好文档沙角A发电厂4号发电机转子漏氢分析林史峰（沙角发电总厂，广东东莞511761）摘要：沙角A发电厂4号发电机大修投运后，存在转子径向导电螺杆漏氢问题。经分析，漏氢的原因是导电螺杆内部轴向引线及螺孔的配合存在问题，破坏了静态时的密封结构，使得冷态时密封圈密封不好造成漏氢现象。最后，提出了处理建议。关键词：发电机转子；导电螺杆；漏氢；返修沙角A发电厂4号、5号发电机QFN3002是上海电机厂引进美国西屋公司技术生产的全氢冷汽轮发电机，分别于1993年5月和7月正式移交电厂投运。4号机在1996年4月进行第1次大修并对定子端部实施加固改造。自投产以来，该发电机转子1号径向导电螺杆一直存在漏氢
2、问题，严重威胁机组的安全运行，电厂与厂家人员一起反复处理了多次，仍然未彻底解决。1发电机转子径向导电螺杆的设计结构发电机转子径向导电螺杆和励磁引线结构如图1所示。其中，径向导电螺杆总长度为285mm，表面包有绝缘层，其离心力全部由与内部轴向引线锥型螺纹拧合处承载，因此轴向引线和径向导电螺杆都采用导电及机械性能较好的锆铜锻件加工而成。密封圈由6个氯丁橡胶密封圈组成，密封圈的压帽为普通钢螺帽。发电机励磁侧联轴器上的2个排气孔（螺孔）是作为转子漏氢时排氢之用，防止氢气漏入励磁装置的外罩内而产生爆炸危险，在做转子气密试验时必须用螺塞封闭。1排气孔；2发电机励侧联轴器；3径向导电螺杆；4丁型引线；5黄铜
3、螺帽；6密封圈压帽；7铝垫圈；8密封圈；9钢垫圈；10钢弹簧；11绝缘套管；12绝缘垫块；13导电螺杆锥牙；14内部轴向引线；15绝缘楔条；16直角型挠性引线2漏氢处理a）1994年5月27日，沙角A发电厂4号主变压器因内部发生故障，机组停运处理近3个多月。停机初期发电机内氢压下降较快，查漏后发现发电机励磁端联轴器上的排气孔漏氢，手感明显，可以判断转子径向导电螺杆有泄漏。8月10日上海电机厂来人紧固两侧导电螺杆密封圈的压帽，但仍有轻微漏氢，因主变压器急需充电，故未做进一步处理。8月31日厂家来人取出导电螺杆做密封试验，发现1号导电螺杆环氧绝缘层脱壳，气压升至539kPa时漏气。返厂重包导电杆绝
4、缘层并加工表面，回装后按厂家说明书要求用137MPa的氮气做转子中心孔静态密封试验合格，发电机投运。b）1995年3月9日，4号机组因炉爆管停机后转小修，发电机吊开励磁侧上半端盖，由厂家检查定子绕组端部是否有开焊现象。23日发电机转子中心孔气密试险发现有泄漏，之后在不抽转子情况下对两侧径向导电螺杆的压帽进行紧固，重做试验合格。c）1996年2月13日，机组调峰停机期间，机内氢压突变下降，每天降低约25kPa，经检查判定径向导电螺杆有漏，未做处理，但开机后恢复正常。d）1996年4月发电机大修期间，做转子中心孔密封试验，发现1号导电螺杆漏气严重而无法升压。外观检查该处压帽退出约5个螺牙的高度，而
5、另一侧（2号杆）退出约2个螺牙，经紧固后仍漏气严重。取出1号导电螺杆单独试验完好，绝缘层未脱壳。更换全部密封圈后回装，因压帽无法完全旋进，将铝垫圈由13mm厚改为11mm厚，再重新拧紧使压帽顶端与孔顶面齐平，不露出螺牙，后做转子密封试验及直流电阻测试均合格。e）1997年2月4日4号机调峰停机过春节，11日突然漏氢很大，12日查为转子漏氢，后将机内氢压降至147kPa，但每天还需补氢约80m3来维持此压力。3月3日机组转为小修，经检查发现1号导电螺杆压帽已退出34螺牙的高度，取出1号导电螺杆检查正常，擦洗导电螺杆的锥牙，更换整套密封圈后回装，使压帽旋进低于孔顶面近2个螺牙的高度，冲铆锁定，但锁
6、不好，做转子密封试验正常。在取出1号导电螺杆的前后，从导电螺杆的顶端至直角型挠性引线端面用电桥测量直流电阻，检查导电螺杆锥牙的电接触情况，检修前测得1号、2号导电杆的电阻分别为150和88，检修回装后，再测则1号导电杆的电阻为62，电阻大大下降。f）1998年4月7日4号机调峰停机期间，突然发生严重漏氢，氢压下降约20kPah，查漏发现励磁侧联轴器排气孔直吹出氢气，机组申请临修。8日电机厂来人检查发现1号转子径向导电螺杆又严重漏氢，取出松动的1号导电杆压帽进行测量，认为螺牙外径偏小02mm，由本厂修配加工新压帽，螺牙外径比原设计放大01mm，并将压帽高度加长至18mm（原为16mm），新压帽上
7、紧后做转子密封试验基本合格，但在充氢后开机前仍可检测到微弱的漏氢，因临修工期已到，未能进一步检查。20日开机后补氢至正常压力运行，恢复正常。g）1998年9月11日，发电机随机组停机小修，倒氢前在运行氢压下查漏未发现有漏，12日倒氢后抽出转子检查，发现1号导电杆的压帽露出约3个螺牙的高度，但不松动。后由厂家将1号导电螺杆取出，现场全面测量有关尺寸（包括径向孔的孔径、深度、表面粗糙度等），结果均符合图纸要求，未发现问题。厂家因此认为以往的漏氢是由于密封圈的压缩量不够引起的，故将原铝压圈（厚度11mm）更换为18mm的新铝压圈，压帽更换为原设计的新备品（16mm），更换新的密封圈，使密封圈的压缩量
8、达到105mm，比原设计多5mm，将压帽拧进不露出螺牙，暂不做机械冲铆固定压帽，以便下次检查是否松动退出。经处理后转子密封试验正常，投运至今未发现有较大的漏氢，压帽是否退出也未打开端盖检查过。3漏氢分析31漏氢特点a）4号机转子1号径向导电螺杆第1次漏氢是由于绝缘层脱壳所引起，后送回制造厂修理后回装。随后出现的漏氢均是由于密封圈密封不良所产生的。b）4号机1号导电螺杆每次漏氢均出现在机组停机（冷态）期间，开机后（热态）则不漏。c）漏氢时密封圈的压帽均有退出的迹象但所有密封圈良好。d）4号、5号机转子导电螺杆的压帽均出现松动退出现象，但只有4号机的1号导电螺杆反复出现漏氢。324号发电机1号转子
9、径向民电螺杆漏氢分析1号导电螺杆因变形或制造工艺上的原因，造成与内部轴向引线及螺孔的配合存在问题，热态时几千安培的励磁电流使J型引线和内部轴向引线发热分别向相反方向膨胀（如图1所示），造成径向导电螺杆不垂直而使密封变形，破坏静态时的密封结构，但由于高速旋转下的离心力作用的发热膨胀，使得密封圈仍然压紧，不致漏氢。冷态时，由于密封圈的离心力变形和发热膨胀很快消失，而压帽松动退出后，密封圈在自身弹力下的压迫变形无法克服因导电螺杆不垂直引起的变形，使密封圈密封不好而造成冷态时的漏氢现象。4看法和建议a）转子径向导电螺杆压帽运行中退出的现象在A厂的2台300MW机组中均出现过。如1998年5月5号机小修
10、中就发现2根导电螺杆的压帽均退出只剩2个螺牙扣住，十分危险！但只有4号机1号导电螺杆出现漏氢，因此压帽的松动只为漏氢提供条件，而不是引起漏氢的真正原因。b）压帽的普遍松动退出却带来一个更危险的安全问题，因为完全有可能在运行中飞出造成设备的严重损失，所以应以高度重视。从结构上看，原设计中的压帽是采用简单的机械冲铆来固定，很不可靠，应加以改进。c）4号发电机1号径向导电螺杆的漏氢，主要是由于变形或工艺上的原因所引起，估计是在第一次绝缘脱壳后返厂修理过程中造成导电螺杆变形、配合不好引起。最后一次是采用增加密封圈的压缩量来处理，虽然在1999年的停机中未出现过较大的漏氢，但在励侧联轴器排气孔处还能检测
11、到微弱的氢气，所以增加密封圈压缩量来保证密封是治标不治本的方法，长期的热力变形可能导致更大的问题，如导电杆螺纹的损坏、导电杆绝缘的损坏等。d）为彻底解决漏氢问题，建议在机组大修时将导电杆和内部轴向引线段取出返厂重新加工装配，同时可考虑将直角型挠性引线背面的绝缘垫块下端作局部修整，以减少轴向引线因热胀冷缩对径向导电螺杆保持垂直的影响。Editors note: Judson Jones is a meteorologist, journalist and photographer. He has freelanced with CNN for four years, covering sever
12、e weather from tornadoes to typhoons. Follow him on Twitter: jnjonesjr (CNN) - I will always wonder what it was like to huddle around a shortwave radio and through the crackling static from space hear the faint beeps of the worlds first satellite - Sputnik. I also missed watching Neil Armstrong step
13、 foot on the moon and the first space shuttle take off for the stars. Those events were way before my time.As a kid, I was fascinated with what goes on in the sky, and when NASA pulled the plug on the shuttle program I was heartbroken. Yet the privatized space race has renewed my childhood dreams to
14、 reach for the stars.As a meteorologist, Ive still seen many important weather and space events, but right now, if you were sitting next to me, youd hear my foot tapping rapidly under my desk. Im anxious for the next one: a space capsule hanging from a crane in the New Mexico desert.Its like the set
15、 for a George Lucas movie floating to the edge of space.You and I will have the chance to watch a man take a leap into an unimaginable free fall from the edge of space - live.The (lack of) air up there Watch man jump from 96,000 feet Tuesday, I sat at work glued to the live stream of the Red Bull St
16、ratos Mission. I watched the balloons positioned at different altitudes in the sky to test the winds, knowing that if they would just line up in a vertical straight line we would be go for launch.I feel this mission was created for me because I am also a journalist and a photographer, but above all
17、I live for taking a leap of faith - the feeling of pushing the envelope into uncharted territory.The guy who is going to do this, Felix Baumgartner, must have that same feeling, at a level I will never reach. However, it did not stop me from feeling his pain when a gust of swirling wind kicked up an
18、d twisted the partially filled balloon that would take him to the upper end of our atmosphere. As soon as the 40-acre balloon, with skin no thicker than a dry cleaning bag, scraped the ground I knew it was over.How claustrophobia almost grounded supersonic skydiverWith each twist, you could see the
19、wrinkles of disappointment on the face of the current record holder and capcom (capsule communications), Col. Joe Kittinger. He hung his head low in mission control as he told Baumgartner the disappointing news: Mission aborted.The supersonic descent could happen as early as Sunday.The weather plays
20、 an important role in this mission. Starting at the ground, conditions have to be very calm - winds less than 2 mph, with no precipitation or humidity and limited cloud cover. The balloon, with capsule attached, will move through the lower level of the atmosphere (the troposphere) where our day-to-d
21、ay weather lives. It will climb higher than the tip of Mount Everest (5.5 miles/8.85 kilometers), drifting even higher than the cruising altitude of commercial airliners (5.6 miles/9.17 kilometers) and into the stratosphere. As he crosses the boundary layer (called the tropopause), he can expect a l
22、ot of turbulence.The balloon will slowly drift to the edge of space at 120,000 feet (22.7 miles/36.53 kilometers). Here, Fearless Felix will unclip. He will roll back the door.Then, I would assume, he will slowly step out onto something resembling an Olympic diving platform.Below, the Earth becomes
23、the concrete bottom of a swimming pool that he wants to land on, but not too hard. Still, hell be traveling fast, so despite the distance, it will not be like diving into the deep end of a pool. It will be like he is diving into the shallow end.Skydiver preps for the big jumpWhen he jumps, he is exp
24、ected to reach the speed of sound - 690 mph (1,110 kph) - in less than 40 seconds. Like hitting the top of the water, he will begin to slow as he approaches the more dense air closer to Earth. But this will not be enough to stop him completely.If he goes too fast or spins out of control, he has a st
25、abilization parachute that can be deployed to slow him down. His team hopes its not needed. Instead, he plans to deploy his 270-square-foot (25-square-meter) main chute at an altitude of around 5,000 feet (1,524 meters).In order to deploy this chute successfully, he will have to slow to 172 mph (277
26、 kph). He will have a reserve parachute that will open automatically if he loses consciousness at mach speeds.Even if everything goes as planned, it wont. Baumgartner still will free fall at a speed that would cause you and me to pass out, and no parachute is guaranteed to work higher than 25,000 fe
27、et (7,620 meters).It might not be the moon, but Kittinger free fell from 102,800 feet in 1960 - at the dawn of an infamous space race that captured the hearts of many. Baumgartner will attempt to break that record, a feat that boggles the mind. This is one of those monumental moments I will always remember, because there is no way Id miss this.