Kaboom! One way to solve a vibration problem
I have had my share of adventures while with GE – and then with Westinghouse Siemens and then ABB and a few others – the outcomes of which vary from the unprintable to ‘whatever you’re having yourself’. I think that some of us who went out there in the early to mid 1980’s had an interesting time in some of the places we went and I use the word interesting in the Chinese sense – tourists did not and still do not go to some of the corners we ended up in and for very good reason.
Communications too are far and away from what they are today – I recall being in southern Algeria for 10 weeks or so without any ability to talk to anyone by phone and being dependent on written letter for receipt of instructions – or being able to call for help – or just to talk to someone.
I recall on that particular job moving a Frame 3 sideways during alignment by belting the I Beam with a 14 lb sledge hammer – believe it or not it worked – eventually - and I suspect chaps out there today might not be called upon for such heroics. Sadly, I never got to see that particular unit start up but I’ll stand over its alignment any time.
I also take pride in finding an unorthodox solution to a persistent No 2 bearing vibration problem on a Frame 5 in XXXXX – No 16 to be precise (and one which I had aligned twice so I knew it had to be perfect). I am unlikely ever to forget the details.
Having prevaricated for months in the commissioning of a simple tank and pipe water wash skid that someone had sold Sonelgaz for some considerable sum, I arranged to blank off all the relevant piping, connected the water wash skid and duly set it going and the turbine turning on the starting motor. All went swimmingly – dark water came out of the drains, customer duly impressed etc etc – all happy. Unfortunately, the excitement of it all had meant that we had strayed over the allotted time for the washing exercise and the despatching office let it be known that the unit needed to go on line within the next five minutes or so – as otherwise it would not be good for the station management. The water wash skid was duly disconnected and fitters crawled all over the unit removing various blanks in the bleed off lines etc etc. Using the local panel, one or two attempts to start the unit failed – the unit failed to light off and duly timed out after the minute or so firing required.
I checked all the drain valves, bleeds etc and all seemed to be in order – the customer now had forgotten all about the success with the water washing and was focussed on the business of starting the unit up and connecting in to the grid – they were in a mild state of agitation if I recall. I said we’d try to start it again and I jumpered out the firing cut off and allowed the unit to spark for some time more than a minute – maybe only thirty or so seconds perhaps. I came out of the control room and was walking down along the unit amongst a concerned group of management when there was an almighty boom and a great mushroom cloud of steam and smoke emanated from the stack.
I am sure the stack moved. Oddly enough, the unit went on up and duly connected to the grid. However, I must have looked unwell as the locals, who would not normally have been known to have been concerned about my health or appearance, asked if I was OK – to which I struggled to keep a semblance of professional stoicism and said there was no problem.
Keeping a discrete but close enough eye on that unit for the next few days did not reveal any damage or ill operation – in fact, the unit which always had a history of vibration in the main bearing now seemed not to have one – then or for as long as I remained there. I reckoned that the false start drain valve must not have worked (even though there had been water flow from it earlier) and that the base of the exhaust plenum had filled up with water – and that had flashed off just after the unit lit off.
All was well and ended well. I recall that the feeling of relief that no damage seemed to have been done being out on its own in respect of such other experiences as I have had.
Christopher V S Doyle Chartered Engineer, FIEI, FCIArb. CVS Doyle Agencies Coldblow, Kilrane, Co Wexford, Ireland. T + 353 53 913 1852, F + 353 53 913 1280 MT + 353 87 275 4702 e: email@example.com
Last modified Tuesday, Jan-16-2007 05:14 PM