Numerical Analysis of the Fluid Flow in a Channel between Gas Turbines and Heat Recovery Steam Generator

Transcription

1 Recent Researches n Mechancs Numercal Analyss of the Flud Flow n a Channel between Gas Turbnes and Heat Recovery Steam Generator H. Walter, C. Dobas, F. Holzlethner and R. Hofmann Abstract The paper present the results of a study for a specal confguraton of a combned cycle power plant. In ths plant two gas turbnes are nstalled to feed one Heat Recovery Steam Generator (HRSG). The flue gas flow n the channels between the two gas turbnes and the HRSG was analyzed to get a more homogenous flow dstrbuton n front of the frst heatng surface of the HRSG whch s arranged downstream of the gas turbnes. In the study a partcular attenton was placed at the operaton condtons where only one gas turbne s n operaton. The results of the nvestgaton have shown that the measures wth a hgher possblty to get a homogenous flow dstrbuton n front of the frst tube bank arranged downstream of the gas turbne have also a hgher pressure loss and n last consequence they are lnked wth a hgher loss of gas turbne power respectvely a lower effcency of the combned cycle. Keywords Numercal smulaton, gas turbne, heat recovery steam generator, channel flow, CFD-study. I. INTRODUCTION he growng ndustry and world populaton results n an Tncreased demand on energy and as a consequence of ths energy consumpton also n a ncreased emsson of greenhouse gases. In vew of the uncertantes related to global warmng and the avalablty of prmary energy sources, there s a requrement to reduce CO 2 emssons and the energy consumpton. Apart from savng of energy an mportant part can be provded by an ncreased use of waste heat of ndustral applcatons. In the energy and chemcal ndustry there are many applcatons where waste heat can be used by another process. For example the exhaust flue gas of a gas turbne or of a furnace blower can be used n a Heat Recovery Steam Generator (HRSG) to produce steam for another process Manuscrpt receved Aprl 19, H. Walter, s wth the Venna Unversty of Technology, Insttute for Energy Systems and Thermodynamcs, Venna, Austra (correspondng author to provde phone: ; fax: ; e-mal: hemo.walter@tuwen.ac.at). C. Dobas, was a master student at the Venna Unversty of Technology, Insttute for Energy Systems and Thermodynamcs, Venna, Austra untl Aprl (e-mal: chrstne.dobas@gmx.net). F. Holzlethner, s wth the Venna Unversty of Technology, Insttute for Energy Systems and Thermodynamcs, Venna, Austra (e-mal: franz.holzlethner@tuwen.ac.at). R. Hofmann s wth the BERTSCHenergy, Kessel- und Energetechnk Apparatebau, Josef Bertsch Ges.m.b.H. & Co, Herrengasse 23, A-6700 Bludenz, Austra (e-mal: rene.hofmann@bertsch.at). and/or to produce electrcty or for dstrct heatng; the waste heat of a gas engne can be used by a downstream arranged Organc Rankne Cycle (ORC) to produce addtonal electrcty and so on. In e.g. a coal fred power plant the flue gas allocates the heat flux at hgh temperature whose exergy can be used only n an nadequate way. Because the upper temperature level of the superheated steam wth approx. 550 C s much lower compared to the flue gas temperature n the combuston chamber of a power plant wth approx C. An ncrease of the steam parameters cannot be done due to the economc choce as well as the strength of the materal used. Therefore the hgh loss of exergy at the heat transfer n the steam generator should be avoded. The provded exergy at hgh temperature can be used n another and better way n the combuston chamber of a turbomachnery followed by an expanson of the flue gas n an expander where electrcty can be produced. The hgh exergy of the gas turbne exhaust flue gas can be used n a downstream arranged Rankne cycle to produce steam for another process and/or electrcty. The combnaton of the gas turbne and the Rankne cycle s called combned cycle, where the waste heat of the gas turbne cycle s used n a heat recovery steam generator n a most effcent way to ncrease the thermal effcency of the sngle gas turbne cycle. Heavy duty natural gas fred gas turbnes n combnaton wth heat recovery steam generators and steam turbnes represent the state of the art of ths approach [1]. The effcency of the latest combned power plants are very hgh. For example the RWE combned cycle power plant Emsland, unt D n Lngen, Germany wth an Alstom gas turbne GT 26 has acheved an overall effcency for the plant of 59.2% [2] or the Eon-power plant Irshng, unt 4 erected n Irshng, Germany wth a Semens gas turbne SGT H wll acheve a effcency wth the combned power plant of > 60% [3] to [6]. In ths paper the exhaust flue gas flow n the channels between two gas turbnes and one heat recovery steam generator was analyzed wth the help of the commercal CFD- Code FLUENT 6.3. Based on the lmted area for erectng the HRSG the mergng pont of the channels s arranged very close to the entrance of the HRSG (see fgure1 and 2). Under normal operaton condtons the HRSG s fed by the two gas turbnes, whch results n a relatvely even flow dstrbuton n front of the frst heatng surface of the HRSG. ISBN:

2 Recent Researches n Mechancs But n some cases only one of the two gas turbnes s n operaton. Ths results to an uneven ncdent flow n front of the frst tube bank of the HRSG (super-heater SH1) whch should be prevented. Frst results of a study to get a more even flow dstrbuton n front of the frst heatng surface of the HRSG should be presented. II. DESCRIPTION OF THE ANALYZED CHANNEL In fgure 1 the analyzed channels as well as the natural crculaton vertcal type HRSG arranged downstream of two natural gas fred gas turbnes wth a power output of 53 MW each, a flue gas mass flow of 130 kg/s and a turbne outlet temperature of approx. 550 C s presented. The fgure shows the boler ncluded stack, dverter wth bypass stack, feld devces, steel structure and ppe work nsde the boler house. Due to standardzaton of the gas turbnes of the dfferent manufacturers the HRSG have to be optmzed to acheve optmum thermal effcences. Ths drum type boler s a natural crculaton system wth a vertcal flue gas path n top supported desgn and mult-pressure systems. The super-heater temperature s controlled usng spray attemporators arranged between the ndvdual super-heater stages. Table I presents the techncal specfcaton of the HRSG. TABLE I TECHNICAL DATA OF THE HRSG [7] Specfcaton Quantty Maxmum contnuous ratng (hgh pressure) 130 t/h Maxmum contnuous ratng (low pressure) 29 t/h super-heated steam pressure (hgh pressure) 121 bar super-heated steam pressure (low pressure) 4.2 bar super-heated steam temperature (hgh pressure) 515 C super-heated steam temperature (low pressure) 170 C III. MATHEMATICAL ANALYSIS A. Governng equatons of the flud flow For the numercal analyss a three dmensonal computatonal doman s constructed wth the help of GAMBIT (FLUENT [8]) for modelng the channel. The model conssts of the two flue gas ducts and the lower part of the vertcal type HRSG ncludng three super-heater tube banks. Super-heater 1 (SH1) s arranged at the nlet of the flue gas nto the HRSG and super-heater 2 (SH2) and 3 (SH3) are arranged downstream of super-heater 1. The man dmensons of the analyzed channels as well as of the smulated part of the HRSG are presented n the sometrc sketch of fgure 2. In ths fgure t can be seen that the mergng pont of the channels s arranged very close to the entrance regon of the HRSG. Ths was a result of the lmted area for erectng the HRSG. Therefore only a very short calmng secton s avalable for the mergng flue gas. Fg. 2: Man dmensons of channels and HRSG used for calculatons Fg. 1: Sketch of the analyzed steam generator [7] In fgure 1 the analyzed channels between the gas turbnes and the HRSG are also presented. Downstream of the gas turbnes the channel changes from a crcular to a rectangular duct. Both channels merge n front of the HRSG (see also fgure 2). The dscretzaton of the partal dfferental equatons for the conservaton laws s done n Fluent [8] wth the ad of the fnte-volume-method. The pressure-velocty couplng and overall soluton procedure used n ths study s based on the pressure correcton algorthm SIMPLE (Sem Implct Method for Pressure Lnked Equatons) [9]. For the convectve term the Second Order UPWIND scheme s used. Ths gves a good accuracy of the soluton. The steady state computatons of the flud flow n the channels and HRSG are done for three dmensons. The governng equatons for the flud flow are: ISBN:

3 Recent Researches n Mechancs Contnuty equaton: u 0 t x Momentum equaton: u uu p t x x x Energy equaton: h uh t x p j t j u x j g p u x Here u denotes the velocty component n drecton, t the tme, the flud densty and x the Cartesan coordnate. p s the pressure, g j s the gravtatonal acceleraton, h s the specfc enthalpy. j stands for the vscous stress tensor and can be expressed for a Newtonan flud as: u u j 2 uk j j (4) x j x 3 xk wth the dynamc vscosty and the Kronecker delta j. B. Turbulence modelng For modelng the turbulence the realzable k- model wth the standard wall functons was chosen durng the smulaton. The man dfferences between the realzable and standard k- model s gven n the turbulent vscosty t and the new equaton for calculatng the turbulent rate of dsspaton, whch s derved from the exact equaton for the transport of the mean-square vortcty fluctuaton [8]. The partal dfferental equatons n conservatve form for the realzable k- model s descrbed n detal n [8] and can be seen as follow: Turbulent knetc equaton: t k ku Gk x x k x (5) G Y b whch s the same as for the standard k- model. Turbulent knetc dsspaton equaton: t u C S x x 1 x (6) 2 C2 C1 C3 Gb k k wth k C max 0,43; ; S ; S 2 S S 1 j j 5 In these equatons k represents the turbulent knetc energy, the knetc vscosty, G k the generaton of turbulence knetc energy due to the mean velocty gradents, G b the generaton of turbulence knetc energy due to the buoyancy, k and the turbulent Prandtl-numbers for k and, respectvely. The M (1) (2) (3) contrbuton of the fluctuatng dlataton n compressble turbulence to the overall dsspaton rate s represented by Y M and S s the modulus of the mean rate-of-stran tensor. The turbulent vscosty s gven wth: 2 k t C (7) In comparson to the standard k- model the coeffcent C s not constant n the realzable k- model. C s a functon of the mean stran and rotaton rates, the angular velocty of the system rotaton, and the turbulent feld. For the realzable k- turbulence model the suggested default values of FLUENT for the model constants C 1 = 1.44; C 2 = 1.9, k = 1, and = 1.2 are used. For the steady state calculatons the tme dependng term n the equatons (1) to (3) as well as (5) and (6) s dentcal zero. C. Boundary condtons for the smulaton For the numercal smulaton of the flud flow n the channels between the gas turbnes and the HRSG boundary condtons are necessary. At the channel nlet (= gas turbne outlet; see fgure 2) the velocty dstrbuton of the gas turbne exhaust flue gas for the three coordnate drectons x, y and z as well as the gas turbne outlet temperature of the flud wth 550 C are gven. Both gas turbnes have the swrl nto the same drecton. The flud pressure at the outlet of the computatonal doman (downstream of the thrd super-heater) was known from a steady state desgn calculaton of the boler wth Pa. The heatng surfaces of the three super-heater tube banks ncluded n the computatonal doman are modeled as porous medum to consder ther nfluence on the flue gas flow. Ths modelng technque for tube banks n a flue gas pass of a boler s an approved method and was used e.g. n [11] to [14]. The pressure drop across the dfferent tube banks n the convectve pass of the boler are known from the steady state desgn calculaton. For the numercal calculatons n FLUENT the pressure drop aganst the tube bank s converted to a velocty dependent pressure loss coeffcent per m porous meda. The porosty of the porous meda used for the smulatons was 0.7. The heat absorpton of the dfferent heatng surfaces s modelled as snk term n the correspondng porous medum to model the flue gas temperature drop. The values for the absorbed heat per volume unt for the dfferent super-heater tube banks and operaton condtons are presented n Table 2. TABLE II HEAT FLUX FROM THE FLUE GAS TO THE HEATING SURFACES Heatng Surface 2 gas turbnes n operaton 1 gas turbne n operaton super-heater 1 (SH1) kw/m kw/m 3 super-heater 2 (SH2) kw/m kw/m 3 super-heater 3 (SH3) kw/m kw/m 3 The values for the heat fluxes, whch are also known from the desgn calculatons, are for an operaton load of the gas turbnes of 100%. The smulatons where only one gas turbne ISBN:

4 Recent Researches n Mechancs s under operaton (GT 1 n fgure 3) are done n such a way that always the same gas turbne was set out of operaton. In these cases the nlet boundary condtons for the gas turbne out of operaton are replaced by a wall (no backward flow nto the gas turbne out of operaton was possble). Based on the hgh excess ar at the combuston of the fuel n the gas turbne combustor for the exhaust flue gas a smplfcaton for the numercal smulatons was made n that form that the thermodynamc propertes of ar are used. All walls surroundng the channels and the HRSG are modeled as adabatc walls. IV. ANALYZED CHANNEL CONFIGURATIONS For the numercal smulaton of the flud flow n the channels dfferent confguratons are analyzed to get a more homogeneous flow dstrbuton n front of the frst heatng surface of the HRSG n case of only gas turbne 1 (see fgure 3) s n operaton. The flud flow n a channel can be nfluenced wth nserts e.g. perforated plates or baffle plates. But t s also well known that every nstallaton of nserts nto a flue gas duct results n an ncrease of the pressure drop. A consequence of an ncreasng pressure drop downstream of a gas turbne s that the effcency of the gas turbne decreases. As a rule of thumb can be seen that a ncrease of the pressure drop of 1 mbar results n a decreases of gas turbne effcency of approx. 0.05% ponts [10]. Thus the addtonal pressure drop caused by channel nserts must be small as possble. In the study presented n ths paper perforated plates as well as baffle plates are nstalled nto the flow channel. The followng cases are analyzed: 1) No nserts are nstalled nto the flue gas channel (Reference model). 2) Baffle plates nstalled n the center of the flue gas channel close to the mergng pont and also close to the gas turbne outlet; see fgure 6. 3) Perforated plates nstalled close to the mergng pont and the nlet of the HRSG wth a porosty of 0.65 (perforated plates case 1). 4) The same arrangement as n case 3 but wth a porosty of 0.8 (perforated plates - case 2). The pressure loss coeffcent for the perforated plates used n cases 3 and 4 are calculated wth the help of [15]. A. Reference model Fg. 3 shows the velocty dstrbuton of the flue gas n the planes 1 and 2 for the case that both gas turbnes are n operaton. It can be seen n fgure 3 that the ncdent flow to the frst tube bank (SH1) of the HRSG s unsymmetrcal although both gas turbnes are n operaton. As a result of ths behavor on the left sde of the HRSG nlet a vortex area (blue colored) of the flue gas has been buld. Based on the momentum exchange between the flud streams leavng the sngle flue duct, the exhaust flue gas of GT1 s dverted n drecton to the left sde of the HRSG. Ths results n a smaller vortex area durng the operaton wth two gas turbnes. The development of ths uneven flow dstrbuton at the nlet regon of the HRSG s a result of the swrl flow at both gas turbnes outlet. Fg. 3: Velocty magntudes n two planes of the channel wthout nserts (GT1 and GT2 n operaton) Plane 2 s arranged close to the nlet of the flue gas flow nto SH1. The flud flow at the left and at the backsde of the HRSG s much lower compared to the velocty at the rght and at the front sde (entrance nto the HRSG) of the HRSG. The flud structure n plane 2 s very smlar to that n plane 1. V. SIMULATION RESULTS The velocty and temperature plots for all fgures presented n ths paper represent the same secton planes (see fgure 3 and 5). For the presentaton of the velocty two planes are used. The frst plane s arranged at the mddle of the flue gas channel and the second plane at the n front of the frst tube bank. For a better comparson a non-dmensonal form for the results of the flue gas velocty are used. In all fgures the same reference velocty was used. For the presentaton of the temperature dstrbuton four addtonal planes are used. The arrangement of these planes can be seen n fgure 6. Fg. 4: Velocty magntudes at plane 1 (GT 1 n operaton) The velocty magntude for the flud flow durng the operaton wth one gas turbne s presented n fgure 4. The fgure shows an expected result. The unhndered nflow of the flud nto the base frame of the HRSG results n a greater vortex area and n an extreme uneven flud dstrbuton. ISBN:

5 Recent Researches n Mechancs Fg. 5: Temperature dstrbuton of the flue gas (GT 1 n operaton) The temperature dstrbuton of the flue gas n four secton planes (3 to 6) s presented n fgure 5 for the case that only GT1 s n operaton. The non-homogenous flow dstrbuton at the nlet of the HRSG results n an unbalanced temperature profle over the tube banks. At the front sde the uneven temperature streams are stronger developed compared to the backsde of the HRSG. Ths s a result of the hgher flud mass flow at the rght front sde of the HRSG. The temperature dstrbuton of the flue gas for the case where both gas turbnes are n operaton s smlar to the stuaton presented n fgure 8a. Therefore no addtonal fgure wll be presented. In ths case the flow s more homogenous and therefore the temperature dstrbuton n the tube banks s stratfed accordng to the tube banks. B. Baffle plates Fg. 6 shows the velocty dstrbuton of the flue gas n the planes 1 and 2 for the case that both gas turbnes are n operaton. The fgure presents also the desgn and the arrangement of the baffle plates ncluded n the flue gas duct. Fg. 7: Velocty magntudes at plane 1 (GT 1 n operaton) The same behavor as n the reference model can be seen durng the operaton wth one gas turbne. Also n ths case the nfluence of the baffle plates on the flud characterstc s compared to the reference model (fgure 4) small. The flud stream s deflected by the baffle plates n drecton to the mddle of the HRSG, but not n a suffcent way. If we make a look at the flue gas temperature dstrbuton n the flue gas pass of the HRSG then we get a confrmaton of ths statement. Fg. 8: Temperature dstrbuton of the flue gas a) both gas turbnes are n operaton b) GT1 s n operaton Fg. 6: Velocty magntudes n two planes of the channel (GT1 and GT2 n operaton) Compared wth the reference model n fgure 3 t can be seen that the baffle plats nfluences the flud flow only n a small measure. Therefore the vortex area at the left sde of the HRSG (see md-plane 1) further exst but wth a smaller dmenson. The flow dstrbuton at the nlet of the HRSG (plane 2) shows only a mnor mprovement. Fg. 8 shows the temperature dstrbuton of the flue gas passng the tube banks of the HRSG. In fgure 8a both gas turbnes GT1 and GT2 and n fgure 8b only GT1 s n operaton. It s no mprovement gven compared to the results of the reference model. Fg. 8b shows also that on the left front sde of the HRSG a hgher flue gas mass flow stream enters the HRSG. Therefore the downstream arranged tube banks are passed by a flue gas stream wth a hgher temperature whle at the rght front sde the flue gas stream s cooler. In drecton to the backsde of the HRSG the uneven temperature profle along the dfferent tube banks reduces. C. Perforated plates - case 1 Another well known method to get a more homogenous flow dstrbuton s the nstallaton of perforated plates nto a flow duct. Based on the small dstance between the mergng pont of the two channels and the HRSG nlet three perforated plates are nstalled nto the flow channel for the flue gas. The ISBN:

6 Recent Researches n Mechancs poston of the plates s shown n fgure 9. Every perforated plate has the same porosty of 0.65 whch s equvalent to a pressure loss coeffcent of approx Fg. 9: Velocty magntudes n two planes of the channel wth nserted perforated plates (GT1 and GT2 n operaton) Fg. 9 shows the velocty dstrbuton of the flue gas n the planes 1 and 2 for the case that both gas turbnes are n operaton. A comparson wth the reference model shows that a sgnfcant enhancement for the flow n front of SH1 s gven (see also fgure 10). After passng of plate 3 the flud enters the base frame of the HRSG wth a very homogenous and symmetrcal flow dstrbuton over the wdth of the HRSG. However fgure 10 shows also that on every sde wall of the HRSG a small vortex wth a very low velocty has been formed. Ths s a result of the flow deflecton at the nclned base frame and the wall at the backsde of the HRSG. But the nfluence of both vortces on the velocty dstrbuton of the flue gas n the tube banks of the HRSG s neglgbly small. The temperature dstrbuton of the flue gas along the tube banks s not presented for ths analyzed case, but t s smlar to that presented n fgure 8a. Fg. 11: Velocty magntudes at plane 1 wth nserted perforated plates (GT 1 n operaton) D. Perforated plates - case 2 The last analyzed case presented n ths paper deals wth the same nserts n the flue gas duct as presented n secton V, C. The only dfference between the two cases s the porosty of perforated plates. The porosty of the perforated plates was changed from 0.65 to 0.8. Ths results n a pressure loss coeffcent of approx accordng to [15]. Fg. 12 shows the velocty dstrbuton smulated under the new condtons for both gas turbnes n operaton whch s unsurprsng. The hgher porosty of the plates results n a more uneven flud flow. Compared to the result presented n fgure 10, where the flow s very homogenous after leavng the plates, tends the flow under the current nvestgated condtons n drecton to the reference model (see fgure 3). Fg. 12: Velocty magntudes n plane 1 of the channel wth nserted perforated plates (GT1 and GT2 n operaton) Fg. 10: Velocty magntudes n plane 1 of the channel wth nserted perforated plates (GT1 and GT2 n operaton) Fg. 11 shows the smulaton results for the case where only GT1 s n operaton. It can be seen clearly that also n ths case the flow dstrbuton s more homogenous compared to the reference model. The decrease of the unbalance n the flud flow s most sgnfcant. The velocty of the flud s over a wde range of the base frame of the HRSG s approxmately the same. A very small area wth a reverse flow of the flud can be seen n fgure 11 represented by the small blue strpe at the left sde of the HRSG wall. As t can be seen n fgure 12 the flow leans to the rght sde wall of the HRSG and the vortex area starts to grow. But n summery the dstrbuton of the flow s more preferable compared to that of the reference model. The temperature dstrbuton for the flue gas n the tube banks, whch are not presented n ths paper, s smlar to that presented n fgure 8a. Fg. 13 shows the smulaton results for the velocty under the condton that only GT1 s n operaton. As dscussed above the velocty dstrbuton s also n ths case more uneven compared to the results presented n fgure 11 for the hgher value of the porosty. In contrast to the result presented n fgure 11 a more closed flud stream has been formed whch ISBN:

7 Recent Researches n Mechancs results n a greater vortex area wth a smaller velocty of the flud at the left sde of the HRSG. Fg. 13: Velocty magntudes at plane 1 wth nserted perforated plates (GT 1 n operaton) Ths can be seen also n the temperature dstrbuton of the flud along the flue gas pass. In fgure 14 a comparson of the temperature dstrbuton of the flue gas along the tube banks for the analyzed confguratons wth the perforated plates cases 1 and 2 are presented. The fgure shows that a more even temperature profle along the flue gas pass s gven under the condtons of perforated plates wth hgher porosty. Fg. 14 shows also that a hgher flue gas mass flow s gven at the rght sde whle the smulatons wth the baffle plates have shown the hgher mass flow at the left sde of the HRSG. Fg. 14: Temperature dstrbuton of the flue gas (GT1 s n operaton) a) perforated plates case 1 and b) perforated plates case 2 E. Pressure drop and loss of gas turbne power As descrbed above s the nstallaton of nserts nto a flow channel assocated wth an addtonal pressure drop. As mentoned n [10] results an addtonal pressure loss of 1 mbar n a decrease of the gas turbne effcency of approx. 0.05% ponts. Therefore the pressure drop nfluences the decson for a soluton whch should be realzed n a very strong manner. Table III gves an overvew about the addtonal pressure loss as well as the addtonal loss of gas turbne power and effcency for the nvestgated combned cycle power plant. The values ncluded n table III for the pressure loss are a result of the calculatons wth FLUENT and represent the pressure dfference between the gas turbne outlet and plane 2 whch s arranged n front of the frst tube bank SH1. The loss of gas turbne effcency s calculated from the dfference n pressure loss between the referenced model and the models wth addtonal nserts n the channels multpled wth the average effcency loss factor of 0.05% accordng to [10]. reference model baffle plates perforated plates case 1 perforated plates case 2 TABLE III PRESSURE LOSS AND LOSS OF GAS TURBINE POWER gas turbnes n operaton pressure loss [mbar] loss of gas turbne effcency [%] loss of power / gas turbne [MW] Based on the hgher flue gas mass flow at the operaton wth both gas turbnes the pressure loss and n consequence also the loss of gas turbne power s hgher compared to the cases wth only GT1 n operaton. Table III shows also, that the measures wth a hgher possblty to get a homogenous flow dstrbuton n front of the SH1 have also a hgher pressure loss and n last consequence they are lnked wth a hgher loss of gas turbne power respectvely a lower effcency of the combned cycle. VI. CONCLUSION In the present study a specal confguraton for a combned cycle power plant are analyzed. In ths plant two gas turbnes are nstalled to feed one HRSG. The flue gas flow n the channels between the two gas turbnes and the HRSG was analyzed. The goal of the nvestgaton was to get a homogenous flow dstrbuton n front of the frst heatng surface of the HRSG whch s arranged downstream of the gas turbnes. A partcular attenton was placed n the study at the operaton mode wth only one gas turbne. To get a more homogenous flow dstrbuton n front of the frst tube bank of the HRSG the nfluence of dfferent nserts nto the flue gas ducts between gas turbnes and HRSG on the flow behavor are analyzed. The results of the study have shown that the measures wth a hgher possblty to get a homogenous flow dstrbuton n front of the SH1 have also a hgher pressure loss and n last consequence they are lnked wth a hgher loss of gas turbne power respectvely a lower effcency of the combned cycle. For the desgn engneer t s a queston of balance between a more homogenous flow at the entrance of the HRSG and the loss of effcency of the gas turbne. The study has shown that for such a specal arrangement of the power plant no perfect soluton can be found to cover all operaton modes. Every soluton whch wll be realzed depends on the partcular boundary condtons whch are set by the desgn engneer or the power plant owner. ISBN:

8 Recent Researches n Mechancs ACKNOWLEDGMENT The authors would lke to thank BERTSCHenergy, Kesselund Energetechnk Apparatebau, Josef Bertsch Ges.m.b.H. & Co, Herrengasse 23, A-6700 Bludenz, Austra to make avalable the boler and channel data for the present study. Dr. Rene Hofmann: was born n Mödlng, Austra n July He receves hs PhD. degree n Thermal Engneerng at the Insttute for Energy Systems and Thermodynamc n Currently he s actve n R&D for heat engneerng and flud flow mechancs at BERTSCHenergy, Kesselund Energetechnk Apparatebau, Josef Bertsch Ges.m.b.H. & Co, Bludenz, Austra. REFERENCES [1] A. Poullkkas, Introducton to Power Generaton Technologes, New York: Nova Scence Publsher, Inc., [2] Power plant Emsland (2011, Aprl 18) [Onlne]. Avalable: (n German) [3] P. Ratlff, P. Garbett and W. J. Fscher, "The New Semens Gas Turbne SGT5-8000H for More Customer Beneft", VGB PowerTech, vol. 87, pp , [4] U. Gruschka, B. Janus, J. Mesl, M. Huth and S. Wasf, " ULN System for the new SGT5-8000H Gas Turbne: Desgn and Hgh Pressure Rg Test Results", n Proceedngs of the ASME Turbo Expo 2008: Power for Land, Sea and Ar GT2008, June, Berln, Germany, Paper number: GT , pp. 1-7, [5] M. Huth, U. Gruschka, B. Janus, J. Mesl and S. Wasf, " Desgn of the Combuston System for the SGT5-8000H and Frst Experences n the Irschng Power Plant ", VGB PowerTech, vol. 89, pp , [6] W. J. Fscher, "SGT5-8000H Product Valdaton and Operatonal Experence at Irschng 4", n Proceedngs of the PowerGen Europe 2010, June, Amsterdam, Netherlands, pp. 1-15, [7] BERTSCHenergy, Combned Cycle and Cogeneraton HRSG. Josef Bertsch GmbH & Co. KG, Bludenz, [8] Fluent, Fluent 6.3 User's manual. Fluent Inc., Lebanon, NH, USA, [9] S.V. Patankar, Numercal heat transfer and flud flow, Seres n Computatonal Methods n Mechancs and Thermal Scences. Hemsphere Publ. Corp., Washngton, New York, London, [10] R. Dolezal, Combned gas- and steam power plants, Sprnger Verlag, Berln, Hedelberg, New York, 2001 (n German). [11] W. Zhou, A. Marquez, D. Moyeda, S. Nareddy, J. Frato, G. Yu, S. Knarvk and V. Frøseth, Desgn and Test of a Selectve Noncatalytc Reducton (SNCR) System for Full-Scale Refnery CO Bolers To Acheve Hgh NOx Removal, Energy & Fuels, vol. 24, pp , [12] T. Le Brs, F. Cadavd, S. Callat, S. Petrzyk, J. Blondn and B. Baudon, Coal combuston modellng of large power plant, for NOx abatement, Fuel, vol. 86, pp , [13] C. R. Cho and C. N. Km, Numercal nvestgaton on the flow, combuston and NOx emsson characterstcs n a 500 MW e tangentally fred pulverzed-coal boler, Fuel, vol. 88, pp , [14] S. Belosevc, M. Sjercc, S. Oka and D. Tucakovc, Three-dmensonal modelng of utlty boler pulverzed coal tangentally fred furnace Internatonal Journal of Heat and Mass Transfer, vol. 49, pp , [15] E. Fred and I. E. Idelchk, Flow Resstance: A Desgn Gude for Engneers, New York, Washngton: Hemsphere Publshng Corporaton, Prof. Dr. Hemo Walter: was born n Wolfsberg, Austra n December He receved the PhD. degree n Thermal Engneerng from Venna Unversty of Technology n Currently he s an Assocated Professor at the Venna Unversty of Technology, Austra. He has wrtten more than 50 publcatons n the area of thermal engneerng. He became a Member of ASME and WSEAS. Hs current research nterest ncludes modelng and dynamc smulaton of power and chemcal systems, flow nstabltes n two-phase flow, hgh temperature storage systems and heat transfer. DI. Chrstne Dobas was born n Venna, Austra n November She receved a Master degree n Thermal Engneerng from Venna Unversty of Technology n Aprl DI. Franz Holzlethner: was born n Gmunden, Austra n December He receved hs master degree from the Venna Unversty of Technology n Currently he s a PhD. student at the Venna Unversty of Technology, Austra. ISBN: