Numerical simulation of dynamic loads at the steam pipe line of the thermal power plant 'Nikola Tesla B”

Određivanje dinamičkih sila kojima nestacionarna struja fluida deluje na cevovod je neophodno u cilju sagledavanja maksimalnih naprezanja koja deluju na strukturu, spojeve i oslonce, odnosno u cilju dobijanja podloga za projektovanje ovih elemenata na maksimalna dinamička naprezanja. U radu su prikazani metodologija i rezultati računarske simulacije nestacionarnih gasodinamičkih sila koje deluju na parovod tople međupregrejane pare termoelektrane „Nikola Tesla B”. Nestacionarne gasodinamičke sile nastaju usled nestacionarnog strujanja radnog fluida pri delovanju sigurnosno-zaštitnih sistema. Zatvaranje pregradnih ventila ispred tur bine srednjeg pritiska zaustavlja protok pare i dovodi do porasta pritiska ispred pregradnih ventila, i prostiranja i superponiranja talasa pritiska duž parovoda, što izaziva dopunska dinamička opterećenja parovoda. Određivanje dinamičkih fluidnih sila se vrši zajedno sa simulacijom nestacionarnog strujanja pare. Simulacija strujanja i određivanje fluidnih dinamičkih sila su sprovedeni pomoću računarskog programa TEA razvijenog na Mašinskom fakultetu u Beogradu. Dobijeni rezultati su korišćeni u okviru revizije inostranog projekta rekonstrukcije (zamene) parovoda međupregrejane pare na termoelektrani „Nikola Tesla B”. Rezultati proračuna dobijeni programom TEA su upoređeni sa rezultatima inostranog računarskog programa SHOCK i dobijeno je prihvatljivo slaganje.Prediction of the transient fluid dynamic forces that act on the pipe line structure, junctions and supports are important in order to predict the maximum design loads. The paper presents the methodology and results of the fluid dynamic forces prediction for the reheated steam pipe line at the Thermal Power Plant ”Nikola Tesla B”. The dynamic forces are induced by fluid transient flow caused by the action of the plant safety system. Closure of the isolation valves in front of the intermediate pressure turbine stops the steam flow and leads to the in crease of pres sure in front of the isolation valves, pressure waves propagation and super position along the pipe line, which cause additional dynamic loading of the pipe line structure. Prediction of the fluid dynamic forces is performed simultaneously with the simulation of the transient fluid flow. Transient simulation of fluid flow and calculation of fluid-dynamic forces are performed with the computer code TEA (Transient Evaluation Analyses), which is developed at the Faculty of Mechanical Engineering in Belgrade. Obtained results are used for the review of a foreign project on the reconstruction (replacement) of steam pipeline in Thermal Power Plant ”Nikola Tesla B”. Results obtained with the computer code TEA are compared with results of foreign computer code SHOCK. Acceptably agreement is achieved