25 MW Gas G as Turbine MFT MFT-8 -8 for Compressor Driver SATOSHI HATA* 1 HIROSHI FUKUI* 1 MASAHI RO KOBAY KOBAYASHI* ASHI* 1 OSAMU ISUMI* 1
Recently, energy conversion from petroleum to natural gas is being promoted, and plant constructions of gas pipe li nes and and gas gas fields fiel ds are increasing globall globall y. I n plants pl ants havi ng 25 25 MW class com compresso pressorr s, gas gas turbines tur bines are often often used use d as co comp mpress resso or dr ivers. Against thi t his s bac background kground,, M it subishi H eavy I ndustri es, L td. (MH (M H I ) has mod modifi ifi ed it s 25 25 M W gas tur bine M F T -8, highly hi ghly noted noted for mari ne propulsi propulsi on and power power ge generati neratio on use, for comp compress resso or dri ve ver, r, and evaluated the performance and reliability of the equipment in shop load test. As a result, the installation space of gas tu turbi rbi ne is r educ educed ed by about about 40% as com compared pared wit h gas turbin tur bines es of the same same cl cl ass of of other manufactur manu factur ers. I n shop ac actual tual l oa oading ding test, r eli eliabil abil it y of the equipme equipment nt i s confir confir me med, d, and at the th e rated load, load, the th e same same hi gh thermal efficiency as that of the original MFT-8 is confirmed, while in addition at partial load, sufficient practical perfor- mance is observed.
T able 1 shows the main characteristics of gas turbine Table M F T-8 for for comp mpress resso or dri drive ver. r. Whi le maintainin maintain ing g the high thermal efficienc effi ciency y of of the ori ori ginal M F T-8, it has bee been n opopti mall mally y modifi modifi ed for for co compre mpresso ssorr dri ve ver. r. To be be appli appli cable to l ong-te ng-term rm conti conti nuous ope operat ration, ion, which is an essential point as gas turbine for compressor driver, parts of the structure have been simplified from fr om the original ori ginal M F T-8 whi ch has bee been n devel devel op oped ed be be-cause of the necessity for reduction of weight and quick starting as a marine propulsion engine.
1. IInt In Intr ntr tro oduc ducti ti on roducti roduc Recently, as energy conversion from petroleum to natural natu ral gas i s bei bei ng promote promoted, d, plant co constr nstr ucti uctions ons of of gas pipe li l i nes and gas gas fields fi elds have bee been n i ncreas ncreasii ng globall globall y. I n pl ants having havi ng 25 MW cl ass co comp mpress resso ors, ga gas s tur bines are often used as drivers. M H I 's 25 25 MW gas turbine MF T-8 T-8,, which has be been highly evaluated for marine propulsion and power generation use, has been newly modified for compressor driver, and its performance and reliability have been evaluat valuate ed i n shop loa l oad d test.
Table 1 Specifications of MFT-8 for compressor compressor driver
2. Mod M Modification odii fi ca cati ti on for for compressor for compressorr dr compresso driver i ve verr
Specifications Simple cycle 3-shaft
Type
F ig. i g. 1 is a cross cross section section of the modifi modifi ed gas gas tur bine M F T-8 for for co compre mpresso ssorr dri ve ver. r. T hi s gas gas tur bine is comcomposed po sed of a gas gas generat generator or GG8 G G8 based based on on the t he air craft engine of P ratt & Whi W hitney tney Power Power Syste S ystems ms (P (PWP WP S), and a po powe werr turbine turb ine of of M HI .
Output
(kW)
26 800*
(%)
38.7*
Thermal efficiency
(min 1)
Operating range
-
3 333 (70%) (70%)
Natural gas fuel
Fuel type Power turbine lubricating oil
ISO-VG 32 (Mineral oil)
Exhaust Compressor Gas generator Combustor GG 8 Structure Turbine
Package dimensions
Gas generator (GG8)
Rotating direction
High pressure, axial flow, 7 stages Cannular, 9 cans High pressure, axial flow, 1 stage Low pressure, axial flow, 2 stages
GG8: ball-and-roller PT: tilting pad bearing
Bearing type
Power turbine
Low pressure, axial flow, 8 stages
Axial flow, 3 stages
Power turbine (PT)
Inlet
(105%) - 5 000 (105%)
(m)
L9.9
W3.2
x
x
H3.5
Clockwise (view from compressor side)
* Values in ISO standard atmospheric condition, using gas fuel,
Fig. 1 Cross section of compressor driver MFT-8 MFT-8
without inlet and exhaust loss, at shaft end.
M itsubishi H eav avy y I ndus ndustri tri es, Lt d. Technical Tec hnical R ev eview iew Vol. 41 N o. 3 (J un. 2004) 2004)
*1 Hiroshima Machinery Works
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3 Principal changes are shown in Fig. F ig. 2 and Fig. 3. 2.1 Power turbine T he power turbi ne of the ori ginal M F T-8 uses ball and-roller bearings, and expensive synthetic oil is used as lubricating oil . F or the compressor dri ver, the bearings of the power turbine are changed to tilting pad bearings, and mineral oil is used for lubrication, thus reducing the running cost.
As a resul t of the change of bearing type of the power tur bine, the lubricating oil drain temperature is lowered by about 50oC. The thermal stress generated in the exhaust frame around the bearing was tested by unsteady F E M analysis as shown in F ig. 4 4, and the reliabil ity was verified. I n t he stress concentrat ed porti on of beari ng support, its stress level was low, and it has been confirmed that there is no problem in low cycle fatigue strength. 2.2 Auxil iar iary y equipment equipment Major changes in the gas turbine are as follows. (1) Change of control method F ig. 5 shows a gas tur bine operati on screen, and F ig ig.. 6 shows an monitoring screen for the gas turbine and compressor.
Power turbine shaft (Hollow shaft Solid shaft)
Gas flow
Journal and thrust bearings (Ball-and roller Tilting pad design) Fig. 2 Improvements to power turbine Added guide rail for maintenance
MFT-8 Start & Stop button
Control devices
Exhaust Inlet
Fig. 5 MFT-8 control touch panel Re-arrangement of piping route and auxiliary equipment Fig. 3 Improvements to auxiliary equipment
Power turbine casing High
l e v e l s s e r t S
Gas flow
Stress concentration portion
Low Bearing support Fig. 6 Monitoring screen for operation condition of MFT-8 gas turbine and compressor
Fig. 4 Unsteady thermal stress analysis
Mi tsubishi Heavy I ndustri es, Lt d. Technical Review Vol. 41 No. 3 (J un. 2004)
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Oil console (for power turbine and compressor)
Oil cooler
Fire extinguishing equipment
0 0 2 3
0 0 4 6
Inlet air silencer
Oil console (for gas generator)
Exhaust silencer
Ventilation filter
Inlet air filter 0 0 0 2 1
Cooler MFT-8 gas turbine Compressor
Ventilation fan
GL
Ventilation damper 5700
9900
9500
Fig. 7 Package arrangement of MFT-8
As the control device of gas generator of PWPS, Micronet of Woodward i s used, whil e the PL C of Al lenBradley is used as the control device of the power turbine of MH I . Further, by automating starting of the gas turbine main body and starting of the auxiliary machine, acceleration up to 70% of power turbine rotating speed (lowest speed in operation range 3 333 min-1) is realized in a single acti on. I n decelerati on, a functi on i s provided for selecting the step-down method automatically depending on the cause of stop, and this is automated including stopping of auxiliary machine. (2) improvement to the enclosure structure M aint enance rai ls ar e provided in the enclosure, the engine can be removed without di sassembly the enclosure, and easy maintenance is realized.
ti on area is reduced by about 40% as compared with other manufacturers.
4. L oad and performance test A tr ial machine of M F T-8 for compressor dri ver was fabricated in accordance with these changes and modifications, and a shop load test was conducted for the purpose of evaluati ng the r eliabili ty and performance of the equipment. F ig. 8 shows an outl ine of the load test facil ity. A water dynamometer was used as the load device.
Exhaust duct and silencer
3. Comparison Compari son wi th other manufactur ers Fig. F ig. 7 shows the example of the typi cal arr angement of compressor train wit h M it subishi A dvanced Compres T abl e2 sor (MAC ) and MF T-8 for compressor driver, and T Tabl able shows a comparison of gas turbine package dimensions of the same class from other manufacturers. The package is made compact by adjusting the piping route and equipment layout, and the package installa-
Ventilation duct and silencer
Inlet air duct and silencer
Ventilation fan
Water dynamometer
Table 2 Comparison of gas turbine package dimensions (Unit: m)
MHI (MFT-8)
Manufacturer A
2 . 3 = W
L=9.9
Installation area 32 m2
Manufacturer B
4 . 3 = W
L=15.3
0 . 4 = W
Oil console for GG 8
L=12.8 52 m2
51m2
Fig. 8 Outline of test equipment for MFT-8
Mi tsubishi H eavy I ndustri es, Lt d. Techni cal R eview Vol. 41 No. 3 (J un. 2004)
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100 ) C 95 o ( . p 90 m e t l 85 a t e m80 g n 75 i r a e b 70 e n 65 i b r u t r 60 e w o 55 P
100
At 100% power turbine speed
50 20 000
Expected performance curve in ISO condition at100% speed (100% rotating speed: 4 762 rpm)
90 80
Active side thrust bearing metal temp.
70
#1 journal bearing metal temp.
60 50 40
#2 journal bearing metal temp.
30 Inactive side thrust bearing metal temp.
10
Power turbine shaft vibration 21000
22 000
20
23 000
24 000
n o i t a r b i v t f a h s e n i b r u t r e w o P
0 25 000
40 38 ) 36 % ( 34 y c n 32 e i c i f 30 f e l 28 a m r e 26 h T
24 22
Measurement points Test condition* : Expected performance curve in 100% speed (100% rotating speed: 4 762 rpm) *Test condition o Ambient temperature: 10 C Atmospheric pressure: 101.90 kPa Inlet loss: 90 mmAq Exhaust loss: 160 mmAq
20 15 000
Power turbine shaft end output (kW)
Expected performance curve in ISO condition at maximum continuous rotation (MCR) (MCR: 5 000rpm)
20 000
25 000
Power turbine shaft end output (kW)
Fig. 9 Measurement results of power turbine bearing metal temperature and shaft vibration
Fig. 10 Measurement results of power turbine performance
To confir m the reliabil ity of the improved points of the power turbine, about 100 points were measured and the data were collected in real time. F ig. 9 shows the resul ts of measur ement of beari ng metal temperature and shaft vibrati on at high l oad with power turbine 100% rotating speed. The metal temperatures of thrust bearings and journal bearings at rated load were, respectively, about 97oC and about 75oC, which fall within design allowable values, and reliability was confirmed. Shaft vibration at rated load was about 30 u mP -P , whi ch was also wit hin design al lowable values. At other points, measurements were normal, which reliability of the equipment was verified. Fig. F ig. 10 10 shows the result s of measurement of performance. I t was confirmed that performances at the rat ed point and partial load were as planned. Thus, at the rated load, the hi gh thermal efficiency of the ori ginal M F T-8 is maintained, and at partial load, sufficient practical performance coul d be confi rmed.
5. Conclusions M H I 's 25 MW gas turbine MF T-8, in widespread use for marine propulsion and power generation purposes, has been modified for compressor driver. T he contr oll abil i ty and maintai nabil i ty have been improved accordingly, and the installation space of gas tur bine is r educed by about 40% as compared with gas turbines of the same class made by other manufacturers. Reli abili ty of the modifi ed MF T-8 has been confirmed in shop load test. I t was veri fied that the modifi ed MF T8 has the same high thermal efficiency as the original MFT-8 at rated load, and has sufficient practical performance at partial load. I n future, the product wil l be brought to the gas field market as a total package of M itsubishi Advanced Compressor (MA C) and M F T-8 gas turbine.
Satos hi Hata
Hiros hi Fukui
Masahiro Kobayashi
Osamu Isumi
M itsubishi H eavy I ndustri es, Ltd. Techni cal R eview Vol. 41 No. 3 (J un. 2004)
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