PRELIMINARY EXPERIMENTS OF THE NEW FACILITY AND TECHNOLOGY FOR VACUUM DRYING AND THERMAL POLIMERIZATION OF THE TURBOGENERATORS STATOR BARS INSULATION (INTEPOL) G. MATEESCU 1 A. MATEESCU 1 C. SAMOILĂ 2 D. URSUŢIU 2 Abstrct: This pper presents the Preliminry Experiments of the New Fcility nd Technology for Vcuum Drying nd Therml Polymeriztion of the Turbogenertors Sttor Brs Insultion (INTEPOL), chieved in 2008 yer by the uthors t SC Alstom Generl Turbo SA, in the frme of the PNCDI 2 (Innovtion Progrm). The vcuum drying nd therml polymeriztion of the turbogenertors sttor brs insultions is used for eliminting of the voltiles from the turbogenertor coil insultion in order to increse their brekdown voltge. The vcuum nd the temperture re the most importnt prmeters of the technologicl process with gret influence on the brekdown voltge of the sttor brs insultion. Key words: vcuum drying, therml polimeriztion, turbogenertor sttor brs insultion. 1. Introduction The processes of the vcuum drying nd the therml polymeriztion by izosttic pressuring with wrm nd fluid bitumen in the INTEPOL Fcility is performing lterntively in two Autoclves, with the following technicl dt: V 1 115.3 m 3, D 1 3.5 m; L 1 11.5 m - for Autoclve-1 nd V 2 140 m 3, D 1 3.5 m; L 1 13.5 m, for Autoclve-2, but could be performed lso only in the Autoclve 1. In order to llow the vcuum drying nd therml polymeriztion of the turbogenertor coil insultion the INTEPOL Fcility, contins the following systems/ equipments [4]: 1. Two Technologicl Chmbers (Autoclve-1 nd Autoclve-2); 2. Four Bitumen Reservoirs (2 pcs for Autoclve-1 nd 2 pcs. for Autoclve-2); 3. Two Vcuum Pumping Systems (one for Autoclve-1 nd one for Autoclve-2); 4. Two Heting Systems with Wrm Oil for the Autoclves nd Bitumen in the Reservoirs; 5. An Oil Reservoir for the Heting Oil; 6. Two Vent Systems for the Nitrogen in 1 Hori Hulubei Ntionl Institute of Physics nd Nucler Engineering - Buchrest. 2 Trnsilvni University of Brşov.
156 Bulletin of the Trnsilvni University of Brşov Vol. 2 (51) - 2009 Series I the Autoclve; 7. The Utilities Systems (Electricity, Cooling Wter nd Compressed Air Systems); 8. A Nitrogen Compressing System for: - Bitumen Trnsfer between Bitumen Reservoirs nd Autoclves; - Pressuring with N 2 t 7 br of the bitumen in the utoclves during the polymeriztion process; - Recupertion of the nitrogen from Autoclves in the Nitrogen-Gs Reservoirs; - Three Storge Reservoirs for the Nitrogen Gs; 9. One Storge Reservoir for the Liquid Nitrogen. 2. Experimentl Detil After ending the construction nd the montge of the new fcility we hve performed the first experiments to know the rel prmeters of the new Vcuum Pumping System of the INTEPOL plnt. 2.1. The Finl Pressure (p f ) nd the Compression Rtio (K) of the Pumping System The Pumping System of the new fcility nd technology (INTEPOL) contins the following most importnt components, from Pfeiffer Vcuum [3]: 1. Four Rotry Vne Pump type BA 501, with totl pumping speed of 4 x 500 m 3 /h nd ultimte pressure of 6 10 2 mbr. 2. One Roots Pump type Okt 6000, with pumping speed of 6000 m 3 /h nd compression rtio 5 < K 0 < 70 (depending on the type of the gses flow rnge, lminr or moleculr). 3. Four Angle vlve with DN 100 ISO- K, for isoltion of the Rotry vne pump. 4. One Wter Vpor Condenser type Cds-2-DN 160/DN 160. 5. One controller type TPG 256 with 6 mesuring chnnels equipped with 6 Pirni guges for monitoring of the pressure: of every preliminry pump, inside of the wter vpor condenser nd inside of the utoclve. 6. The Vcuum Pumping System is isolted from the New Autoclve by specil electropneumticl vlve (6-163) for vcuum nd pressure (10 3 mbr until 7 br) with DN 250 from Klinger. It is well known tht [1], [2]: the pumping speed, S dv dt V, t is the men volume flow through the cross section of the inlet port of vcuum pump nd it is indicted in m 3 /h; m 3 /s or L/s; the pumping cpcity (throughput), dv m p q pv S p p V, dt t t denotes the gs throughput in vcuum pump s function of the inlet pressure l l nd it is indicted in P or mbr. In s s Pumping System the throughput of ny pump is the sme; the finl/ultimte pressure (p f ) is the lowest pressure tht is symptoticlly pproched by the pressure of blnkflnged pumping system, without gs inlet; p2 the compression rtio, K 0, is p1 the pressure rtio between the dischrge pressure p 2 nd the intke pressure p 1, of pump or of pumping system: In the cse of blnk-flnged inlet ports, the compression rtio is mesured through gs inlet on the dischrge side, becuse ny vcuum pump hs bckflow loses through gps (L P (p 1 p 2 ), where L P is the conductivity of the pump). The bckflow loses through gps limit the compression rtio of pump or of pumping system.
Mteescu, G., et l.: Preliminry Experiments of the New Fcility nd Technology 157 If we consider our Vcuum Pumping System with Roots pump (OKTA 6000, hving pumping speed S 0, nd compression rtio K 0 ), connected to Technologicl Chmber nd n dditionl Rotry Vne Pump (4xBA 501, with pumping speed S 0, tht ensure vrible pressure p v t the exhust of the Roots pump), connected to the dischrge of the Roots pump, nd by tking into considertion the lw of throughput continuity of vcuum system we cn obtin the rel compression rtio of the Roots pump from the eqution of the continuity of the throughput in ny moment: q p V p S p S L ( p p ) S p 0 R v R V, (1) where: p - the intke pressure ( vrible pressure from tmospheric pressure to the ultimte pressure of the pumping system); p v - the bcking vcuum pressure ( vrible pressure t the Roots dischrge port); S 0 - the pumping speed of the Roots pump; S R - the return pumping speed of the Roots pump; S R p v - the return gs flow from the dischrge side of the Roots pump; S - the rel pumping speed of the Roots pump; L R - the conductivity of the Roots pump. At finl pressure of the Pumping System we cn consider tht S 0 nd we cn clculte the rel compression rtio of the Roots pump (K): p S L ( p p ) + S p 0 R V R V, (2) p S ( L + S ) p K L p 0 R R V R, (2b) p p v 0 S S R + + L L R R. (3) By closing of the Klinger vlve (6-163) the ultimte pressure of the pumping system, mesured with the Pirni guge of 3 the TPG 256 controller, ws 3 10 mbr (p 1 ). Also the ultimte pressure t the exhust port of the Roots pump (p 2 ) ws 2 9 10 mbr. The rel compression rtio of the Roots pumps which ws obtined is: 2 9 10 K 30, 3 3 10 nd this vlue is in correspondence with the compression rtio of the Pfeiffer Vcuum Roots pumps. 3. Results 3.1. Lek test result for the New Autoclve The lek test of the new nd clened utoclve ws mde t norml room temperture nd fter 24 hours of pumping of the utoclve by isolting it from the pumping system nd by mesuring the incresing of the pressure in time in the utoclve (due to degssing processes nd due to the lekges). The results of the lek tests re presented in the Tble 1 nd in Figure 1. In order to eliminte the influence of the degssing process to the lekge of the utoclve the test will continue by heting of the utoclve in future. No. Hours Lek test Tble 1 Pressure in the technologicl chmber p i [mbr] 1 10.02 5.20 x 10 2 2 10.05 1.26 x 10 1 3 10.06 1.50 x 10 1 4 10.12 2.50 x 10 1 5 10.17 3.44 x 10 1 6 10.22 4.44 x 10 1 p 0.444 0.052 0.392 [mbr],
158 Bulletin of the Trnsilvni University of Brşov Vol. 2 (51) - 2009 Series I t 10.22 10.02 20 [min] 1200 [sec], q the leks of the new utoclve: q p V t 0.392 1.4 10 12 10 2 45.73 [mbr L/s]. The lek rte of the utoclve is higher thn the theoreticl estimted vlue. Tking into ccount tht the pumping speed of the OKTA 6000 pump is: 3 6 10 10 6000 [m /h] [L/s] 2 3.6 10 4 21.8 10 [L/s]. The finl pressure tht could be obtined in the new utoclve will be higher thn: 3 3 5 t norml temperture re presented in Tble 2 nd in Figure 2. No. Tble 2 Pumping down pressure evolution in the clen utoclve Pumping time [min] Pressure in the utoclve [mbr] 1 0.00 1.000 2 12.00 500 3 20.00 0.9 4 30.00 0.09 5 40.00 0.08 6 60.00 0.05 7 1440.00 0.04 Pumping down evolution in the clen utoclve 1000 45.73 [mbr L/s] 2 21.8 10 [L/s] 2.098 10 2 [mbr] 0.02098 [mbr]. Pressure (mbr) 100 10 1 1 6 11 16 21 26 31 36 41 46 51 56 61 66 0,1 Lek test 0,01 Time (min) Pressure [mbr] 0,6 0,4 0,2 0-500 0 500 1000 1500 Time [sec] Fig. 1. Lek test 3.2. Ultimte pressure test in the technologicl chmber The results of the experiments for the pumping down pressure evolution in time, in the clen nd empty utoclve Fig. 2. Pumping down evolution in the clen utoclve Due to the leks nd to the big degssing of the technologicl equipment from the utoclve, the finl pressure in the utoclve ws 0.04 mbr (fter 24 hours) nd not 0.020 mbr, s the result from the lek test of the new utoclve. In the next period we will try to find the leks of the utoclve with the technologicl equipments mounted in order to decrese the ultimte pressure in the utoclve under 0.02 mbr.
Mteescu, G., et l.: Preliminry Experiments of the New Fcility nd Technology 159 3.3. The preliminry results of the vcuum drying of the turbogenertors sttor br insultion The preliminry experiments were mde for few times for the vcuum drying of the turbogenertor sttor br insultion (with 20 turbogenertor sttor brs insultion in the utoclve) on period of 22 hours/chrge, with the mesurement of the pressure nd. temperture of the drying process. The results of these preliminry experiments re presented in Figure 3. Pumping down 0,50 Pressure [mbr] 0,40 0,30 0,20 0,10 0,00 0 200 400 600 800 Time [min] ) Temperture evolution of the turbogenertor sttor brs in the vcuum drying process Temperture [Cesius degree] 120,00 100,00 80,00 60,00 40,00 20,00 0,00 0 200 400 600 800 Time [min] b) Fig. 3. ) Pumping down evolution; b) Evolution of the sttor brs turbogenertor temperture in the vcuum drying process 4. Conclusions The fcility nd the technology of the vcuum drying nd therml polymeriztion of the turbogenertor sttor brs insultion represents very complex mchine nd technology nd it will be necessry mny experiments to improve the technologicl equipments of the plnt nd to optimize the technology in order to increse the qulity
160 Bulletin of the Trnsilvni University of Brşov Vol. 2 (51) - 2009 Series I of the turbogenertor sttor coils. The pressure nd the temperture re the prmeters of the technologicl processes of vcuum drying nd therml polymeriztion of the insultion for turbogenertor coils. The brekdown voltge of the insultion of the turbogenertor sttor brs is the finl test tht certifies the qulity of the turbogenertor coils nd the optiml prmeters (pressure nd temperture) for vcuum drying nd therml polymeriztion processes. In order to find the optiml prmeters of the technologicl process (pressure nd temperture) tht will ensure the higher brekdown voltge of the turbogenertor sttor brs insultion, it is necessry to improve the ultimte pressure of the pumping system nd to continue the experiments. To cover the lekge of utoclve with ll the technologicl equipments mounted on it nd to reduce the ultimte pressure of the pumping system in the utoclve under 10 2 mbr it will be necessry to increse the pumping speed of the Roots pump by mounting in prllel of the second Roots pump type OKTA 6000. The preliminry experiments chieved in the period of putting in opertion of the plnt hve proved tht the brekdown voltge of the turbogenertor sttor brs insultion is higher thn the stndrd imposed vlue. Bsed on these first tests with good results, the plnt is now used by the end user for production of the turbogenertor sttor brs. References 1. Pipko, A.: Fundmentls of Vcuum Techniques. Moscow. Mir Publishers, 1981. 2. Umtrh, W.: Fundmentls of Vcuum Technology. Cologne, August, 1998. Avilble t: http://newton.phys. uic.ro/ dt/pdf/vcuum%20technology.pdf. Accessed: 22-03-2009. 3. *** Pfeiffer Vcuum: Ctlog Generl. 2008, p. 1-213; p. 453-545. 4. *** Micfil: Instrucţiuni de funcţionre pentru Instlţi de uscre şi compoundre pentru izolţi brelor turbogenertorelor (Operting Instructions for Instlltion nd Drying Compoundre Brs for Insultion the Turbogenertors). 1969.