Rota­tion­al Vibra­tions in Tur­bines

Tech­nic­al phe­nom­ena in gas and steam tur­bines

Rota­tion­al vi­bra­tions or tor­sion­al vi­bra­tions are gen­er­ally defined as the vi­bra­tions of a sys­tem around a ro­ta­tion­al de­gree of free­dom. Thus at first lin­ear elast­ic os­cil­la­tions around the own body axis. Nowadays, vi­bra­tion phe­nom­ena such as ro­ta­tion­al vi­bra­tions play an enorm­ous role in mod­ern tur­bines, wheth­er gas tur­bines or steam tur­bines. The de­vel­op­ment tends to con­struct ever lar­ger tur­bines with a high­er ef­fi­ciency. Sim­il­arly, as the size and com­plex­ity of a tur­bine in­creases, so does the in­flu­ence of dan­ger­ous vi­bra­tion con­di­tions on the safety of the en­tire sys­tem.

Net-In­duced Tor­sion­al Loads

Chal­lenges due to ro­ta­tion­al vi­bra­tions

One of the biggest chal­lenges in the op­er­a­tion of a tur­bine is fre­quency fluc­tu­ations in the grid sup­ply, as these can pro­mote the oc­cur­rence of forced ro­ta­tion­al vi­bra­tions in the main shaft of a tur­bine. More spe­cific­ally, these vi­bra­tions are caused by dif­fer­ent fed-back in­duced tor­sion­al loads on the tur­bine, com­pressor and gen­er­at­or.

The forced tor­sion­al vi­bra­tions rep­res­ent a danger pre­cisely when their phase or op­er­at­ing speed co­in­cides ap­prox­im­ately or com­pletely with the phase of the sys­tem's nat­ur­al vi­bra­tions. In en­gin­eer­ing, this phe­nomen­on is called a res­on­ance cata­strophe. An un­damped sys­tem re­acts to even the smal­lest ex­tern­al ex­cit­a­tion with strongly in­creas­ing os­cil­la­tion de­flec­tions. The ini­tially elast­ic ro­ta­tion­al vi­bra­tions be­come loads that lead to the break­age of the tur­bine shafts.

Meas­ure­ment and Ana­lys­is Tech­no­logy for a Safe Oper­a­tion

Our solu­tion for pro­tec­tion against ro­ta­tion­al vi­bra­tions

A meas­ure­ment and ana­lys­is sys­tem that mon­it­ors the nat­ur­al fre­quen­cies of the sys­tem and thus en­sures op­er­a­tion out­side the crit­ic­al op­er­at­ing ranges. In crit­ic­al situ­ations, an im­me­di­ate safety shut­down is ini­ti­ated. This pre­vents costly dam­age and down­time.

The IfTA Ar­gusOMDS, our all-in-one solu­tion in com­bin­a­tion with the award-win­ning AT2 input mod­ule and the ana­lys­is soft­ware IfTA TrendView­er, meets pre­cisely these re­quire­ments. The cus­tom­iz­able sys­tems en­able angle-re­lated eval­u­ations of ro­ta­tion­al and tor­sion­al vi­bra­tions in real time. In this way, the dif­fer­ent nat­ur­al fre­quen­cies of the tor­sion­al vi­bra­tions of the tur­bine can be mon­itored and dan­ger­ous vi­bra­tion states avoided. The in­teg­rated real-time ana­lys­is im­me­di­ately ini­ti­ates ne­ces­sary pro­tect­ive meas­ures in crit­ic­al op­er­at­ing areas.

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