Numerical Investigation of Condenser Pressure Effect on Last Stage Operation of Low Pressure Wet Steam Turbines

Stanciu, Mugurel; Marcelet, Meryem; Dorey, Jean-Marc

doi:10.1115/gt2013-94070

Cited by 9 publications

(13 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The accuracy of the steady method improves when the circumferential asymmetry is taken into account, predicting efficiencies closer to that of full unsteady calculations. The picture is further complicated by the seasonal variations of condenser pressure, later work from Stanciu et al [5] has shown that at critically LPs, condensation running down the bearing cone can cause thermal imbalance which compromised the safety of the turbine shaft.…”

Section: Effect Of Computational Approach For Off-design Calculationsmentioning

confidence: 98%

See 1 more Smart Citation

Efficient Methods for Predicting Low Pressure Steam Turbine Exhaust Hood and Diffuser Flows at Design and Off-Design Conditions

Burton

Ingram

Hogg

2015

Journal of Engineering for Gas Turbines and Power

View full text Add to dashboard Cite

The exhaust hood of a steam turbine is an important area of turbomachinery research as its performance strongly influences the power output of the last stage blades (LSB). This paper compares results from 3D simulations using a novel application of the nonlinear harmonic (NLH) method with more computationally demanding predictions obtained using frozen rotor techniques. Accurate simulation of exhausts is only achieved when simulations of LSB are coupled to the exhaust hood to capture the strong interaction. One such method is the NLH method. In this paper, the NLH approach is compared against the current standard for capturing the inlet circumferential asymmetry, the frozen rotor approach. The NLH method is shown to predict a similar exhaust hood static pressure recovery and flow asymmetry compared with the frozen rotor approach using less than half the memory requirement of a full annulus calculation. A second option for reducing the computational demand of the full annulus frozen rotor method is explored where a single stator passage is modeled coupled to the full annulus rotor by a mixing plane. Provided the stage is choked, this was shown to produce very similar results to the full annulus frozen rotor approach but with a computational demand similar to that of the NLH method. In terms of industrial practice, the results show that for a typical well designed exhaust hood at nominal load conditions, the pressure recovery predicted by all methods (including those which do not account for circumferential uniformities) is similar. However, this is not the case at off-design conditions where more complex interfacing methods are required to capture circumferential asymmetry.

show abstract

Section: Effect Of Computational Approach For Off-design Calculationsmentioning

confidence: 98%

“…This is typically done by modeling the full turbine annulus in either a steady frozen rotor calculation or a full unsteady sliding mesh approach [2,5]. The frozen rotor approach has become the most widely adopted method [6][7][8] in recent years for calculating exhaust hood flows.…”

Section: Introductionmentioning

confidence: 99%

Efficient Methods for Predicting Low Pressure Steam Turbine Exhaust Hood and Diffuser Flows at Design and Off-Design Conditions

Burton

Ingram

Hogg

2015

Journal of Engineering for Gas Turbines and Power

View full text Add to dashboard Cite

show abstract

“…At present, most researchers [1,14] assume a uniform outlet static pressure boundary condition at exit from the exhaust hood. However, the presence of the condenser at hood outlet means that in reality this is not the case.…”

Section: Generic Condenser Pressure Gradientmentioning

confidence: 99%

“…This annual variation has been shown to be as large as 0.29 bar (from 0.23 bar to 0.52 bar) for a sea water cooled plant in Finland [13]. An EDF study noted that large, potentially unsafe vibrations in the turbine shaft bearings are present at critical condenser pressures due to a shift in exhaust hood re-circulations which drive water films down the bearing cone causing a thermal imbalance in the shaft [14]. This study also showed that exhaust hood flows can be clearly categorised depending on the condenser operating point.…”

Section: Introductionmentioning

confidence: 99%

The influence of condenser pressure variation and tip leakage on low pressure steam turbine exhaust hood flows

Burton

Ingram

Hogg

2014

Proceedings of the Institution of Mechanical Engineers, Part A:

View full text Add to dashboard Cite

Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. This paper aims to highlight the importance of the accurate computational modelling of both the inlet and outlet exhaust hood boundary conditions. The computations presented are calculated using the public domain LP exhaust diffuser test case proposed by Burton in 2012. The original test case did not include the effect of tip leakage on diffuser flows, this paper describes the inclusion of tip leakage and the results are shown to be in-line with the outputs produced by other authors. The key advance in this paper is that calculations were conducted with a representative condenser pressure gradient caused by the temperature variation inside the condenser tube nest. It is shown that accurately modelling the exit boundary calculation has a large influence on the flow structure and a smaller influence on the pressure recovery inside the exhaust diffuser. This influence is smaller than that seen by other authors when including unsteady effects or accounting for the circumferential non-uniformity of the turbine exit flow but will need to be included in design calculations as diffuser design advances. Nomenclature C p = P 2 −P 1 P T 1 −P 1 Static Pressure Recovery c p

show abstract

“…These oscillations, owing to stator-rotor flow interactions or suboptimal operating conditions, may cause otherwise unforeseen accidents. Low-flow operation (Filippenko et al, 2011) (Stanciu et al, 2013) (Tanuma et al, 2015) (Rzadkowski et al, 2016) and rotational instability (Zhang et al, 2011) (Qi et al, 2013) (Megerle et al, 2015) have already been investigated numerically and experimentally. A numerical study concluded that blowing steam jets into the final stage was effective for suppressing the large-scale vortex that can occur under low-load conditions (Haller et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Numerical analysis of condensation effects on final-stage rotor-blade rows in low-pressure steam turbine

Miyazawa

Furusawa

Yamamoto

2017

JFST

View full text Add to dashboard Cite

The causal relationship between unsteady forces of wet-steam flows on rotor-blade rows and the steam condensation in low pressure steam turbines is still one of unresolved issues. In this study, we investigate the effect of condensation on the time-dependent torque of final-stage long-rotor blade rows in a low pressure steam turbine. Then we simulate unsteady wet-steam flows through the three-stage stator-rotor blade rows in the steam turbine while changing the inlet temperature condition. The variation of the inlet temperature results in creating a flow field with a different amount of wetness due to condensation. The temperature and pressure in the flow field obtained from a different inlet temperature are compared with each other, and the torques calculated from the time-dependent pressure on a final-stage long-rotor blade are also relatively compared. The calculated results in this study indicate that the time-dependent torques on the final-stage long-rotor blade significantly depend on the latent heat added by condensation and that the amount of condensation is highly sensitive to variations in the inlet temperature. This study also suggests that an optimal inlet temperature may be exist for optimizing the torque of low pressure steam turbines.

show abstract

Numerical Investigation of Condenser Pressure Effect on Last Stage Operation of Low Pressure Wet Steam Turbines

Cited by 9 publications

References 0 publications

Efficient Methods for Predicting Low Pressure Steam Turbine Exhaust Hood and Diffuser Flows at Design and Off-Design Conditions

Efficient Methods for Predicting Low Pressure Steam Turbine Exhaust Hood and Diffuser Flows at Design and Off-Design Conditions

The influence of condenser pressure variation and tip leakage on low pressure steam turbine exhaust hood flows

Numerical analysis of condensation effects on final-stage rotor-blade rows in low-pressure steam turbine

Contact Info

Product

Resources

About