Operational efficiency of PT-135 and PT-140 turbines with the last stage of the low-pressure part removed and its diaphragm left in place

2006 ◽  
Vol 53 (2) ◽  
pp. 107-109
Author(s):  
G. D. Barinberg ◽  
L. A. Zhuchenko
Keyword(s):  
Low Pressure ◽  
Operational Efficiency ◽  
Last Stage ◽  
Pressure Part

scholarly journals Revalorisation of the Szewalski’s concept of the law of varying the last-stage blade retraction in a gas-steam turbine

2021 ◽  
Vol 323 ◽  
pp. 00034
Author(s):  
Paweł Ziółkowski ◽  
Stanisław Głuch ◽  
Tomasz Kowalczyk ◽  
Janusz Badur
Keyword(s):  
Steam Turbine ◽  
Thermodynamic Analysis ◽  
Spatial Model ◽  
Low Pressure ◽  
Free Vortex ◽  
Axial Turbine ◽  
Last Stage ◽  
The Law ◽  
Pressure Part

The article presents the implementations of the free vortex law to the blade of the last stage of a gas-steam turbine. First, a thermodynamic analysis was carried out, determining the parameters at the inlet, then the number of stages of the high and low-pressure part of the turbine was constructed, together with the kinematics and velocity vectors for subsequent stages of the axial turbine. The last step of article was to take into account the law of variation of the peripheral component of the velocity of the medium working with the radius of the turbine in a discrete way and to make a 3D drawing of the resulting geometry. When creating the spatial model, the atlas of profiles of reaction turbine stages was used.

On efficiency measurements for large steam turbine low-pressure stages

1997 ◽  
Vol 211 (4) ◽  
pp. 347-355
Author(s):  
J Krzyżanowski
Keyword(s):  
Fluid Flow ◽  
Low Pressure ◽  
Measuring Error ◽  
Efficiency Gain ◽  
Natural Question ◽  
Current Trends ◽  
Before And After ◽  
Equipment Modernization ◽  
Last Stage ◽  
Pressure Part

Current trends in the development of power engineering are turning attention towards modernization of the machinery and equipment. Modernization of the LP (low-pressure) part of a turbine is one of the most promising solutions. A natural question which arises concerns the effectiveness of such modernization, i.e. a comparison of the characteristics (efficiency) of this turbine part before and after modernization. Such a comparison may be based on measurements of the efficiency of the LP part and the last stage before and after the modernization, provided that the efficiency gain achieved exceeds the measuring error. This paper deals with the estimation of the accuracy of such a measurement, the principle and methodology of which have been developed at the Institute of Fluid-Flow Machinery (IFFM) for a real turbine.

The Experimental Investigation of the Internal Support Effects on Exhaust Casing Pressure Recovery

2017 ◽  
Author(s):  
Robert Kalista ◽  
Lukáš Mrózek ◽  
Michal Hoznedl
Keyword(s):  
Steam Turbine ◽  
Axial Length ◽  
Low Pressure ◽  
Pressure Recovery ◽  
Geometrical Parameters ◽  
Structural Factors ◽  
Exhaust Hood ◽  
Last Stage ◽  
Pressure Part ◽  
Horizontal Joint

As is well known, the performance of the last stage of the low pressure part of a steam turbine is strongly influenced by the effectivity of the downstream exhaust casing. The efficiency of the exhaust hood depends on many structural factors such as the design of the diffuser parts, dimensions of the outer casing or arrangement of internal supports. The aim of this paper is the experimental study of the influence of the internal supports of the axial-radial exhaust hood on its pressure recovery factor. For one geometry of its diffuser parts a few different variations of internal supports such as T-rib, tube grid or BV were tested. The effect of reducing the width of exhaust hood in the horizontal joint and the changing of axial length of the diffuser were observed. The width of exhaust hood in horizontal joint and the axial length of the diffuser define the area in the horizontal joint of the exhaust hood. How the diffuser behaves when reducing this area is very important in retrofitting of old machines, where there are so many geometric constrains. The effect of wall jet blowing into the diffuser wall was also evaluated. In this paper we concentrate to examine the sensitivity of these certain geometrical parameters of exhaust hood on the pressure recovery of the whole exhaust system of the low pressure part of the steam turbine. The main purpose of our analysis and experimental measuring was optimising the axial-radial exhaust hood of the steam turbine. For this reason, wind tunnel facilities with relevant measuring and traversing systems were designed and built. The measurements have been performed on 1/5th scale test rig which enabled rapid and efficient evaluation of multiple geometrical variants. The observed exhaust hood was designed for an extra long 54inch last stage blade. For measurements of flow parameters was used multi-hole pneumatic pressure probes and wall pressure taps in conjunction with CFD tools to explore physics based alterations to the exhaust configuration.

scholarly journals Failure Analysis in Lacing Wire Of Last Stage Low Pressure Steam Turbine Blade

2021 ◽  
Vol 1096 (1) ◽  
pp. 012097
Author(s):  
A M Kongkong ◽  
H Setiawan ◽  
J Miftahul ◽  
A R Laksana ◽  
I Djunaedi ◽  
...  
Keyword(s):  
Failure Analysis ◽  
Steam Turbine ◽  
Turbine Blade ◽  
Low Pressure ◽  
Pressure Steam ◽  
Steam Turbine Blade ◽  
Last Stage

Sequential vs Multidisciplinary Coupled Optimization and Efficient Surrogate Modelling of a Last Stage and the Successive Axial Radial Diffuser in a Low Pressure Steam Turbine

2014 ◽  
Author(s):  
Kevin Cremanns ◽  
Dirk Roos ◽  
Arne Graßmann
Keyword(s):  
Steam Turbine ◽  
Design Process ◽  
Energy Demand ◽  
Three Dimensional ◽  
Flow Simulation ◽  
Low Pressure ◽  
Steam Turbines ◽  
Low Pressure Turbine ◽  
Pressure Steam ◽  
Last Stage

In order to meet the requirements of rising energy demand, one goal in the design process of modern steam turbines is to achieve high efficiencies. A major gain in efficiency is expected from the optimization of the last stage and the subsequent diffuser of a low pressure turbine (LP). The aim of such optimization is to minimize the losses due to separations or inefficient blade or diffuser design. In the usual design process, as is state of the art in the industry, the last stage of the LP and the diffuser is designed and optimized sequentially. The potential physical coupling effects are not considered. Therefore the aim of this paper is to perform both a sequential and coupled optimization of a low pressure steam turbine followed by an axial radial diffuser and subsequently to compare results. In addition to the flow simulation, mechanical and modal analysis is also carried out in order to satisfy the constraints regarding the natural frequencies and stresses. This permits the use of a meta-model, which allows very time efficient three dimensional (3D) calculations to account for all flow field effects.

The Pressure Field at the Output From a Low Pressure Exhaust Hood and Condenser Neck of the 1090 MW Steam Turbine: Experimental and Numerical Research

2018 ◽  
Author(s):  
Michal Hoznedl ◽  
Antonín Živný ◽  
Aleš Macálka ◽  
Robert Kalista ◽  
Kamil Sedlák ◽  
...  
Keyword(s):  
Boundary Condition ◽  
Steam Turbine ◽  
Cross Section ◽  
Static Pressure ◽  
Cooling Water ◽  
Low Pressure ◽  
Maximum Temperature ◽  
Angle Distribution ◽  
Exhaust Hood ◽  
Last Stage

The paper presents the results of measurements of flow parameters behind the last stage of a 1090 MW nominal power steam turbine in a nuclear power plant. The results were obtained by traversing a pneumatic probe at a distance of about 100 mm from the trailing edges of the LSB (Last Stage Blade). Furthermore, both side walls as well as the front wall of one flow of the LP (Low Pressure) exhaust hood were fitted with a dense net of static pressure taps at the level of the flange of the turbine. A total of 26 static pressures were measured on the wall at the output from the LP exhaust hood. Another 14 pressures were measured at the output from the condenser neck. The distribution of static pressures in both cross sections for full power and 600 and 800 MW power is shown. Another experiment was measured pressure and angle distribution using a ball pneumatic probe in the condenser neck area in a total of four holes at a distance up to 5 metres from the neck wall. The turbine condenser is two-flow design. In one direction perpendicular to the axis of the turbine cold cooling water comes, it heats partially. It then reverses and it heats to the maximum temperature again. The different temperature of cooling water in the different parts of the output cross section should influence the distribution of the output static pressure. Differences in pressures may cause problems with uneven load of the tube bundles of the condenser as well as problems with defining the influential edge output condition in CFD simulations of the flow of the cold end of the steam turbine Due to these reasons an extensive 3D CFD computation, which includes one stator blade as well as all moving blades of the last stage, a complete diffuser, the exhaust hood and the condenser neck, has been carried out. Geometry includes all reinforcing elements, pipes and heaters which could influence the flow behaviour in the exhaust hood and its pressure loss. Inlet boundary conditions were assumed for the case of both computations from the measurement of the flow field behind the penultimate stage. The outlet boundary condition was defined in the first case by an uneven value of the static pressure determined by the change of the temperature of cooling water. In the second case the boundary condition in accordance with the measurement was defined by a constant value of the static pressure along all the cross section of the output from the condenser neck. Results of both CFD computations are compared with experimental measurement by the distribution of pressures and other parameters behind the last stage.

AERODYNAMIC INFLUENCE OF A BLEED ON THE LAST STAGE OF A LOW-PRESSURE COMPRESSOR AND S-DUCT

2021 ◽  
pp. 1-39
Author(s):  
Apostolos Spanelis ◽  
A Duncan Walker
Keyword(s):  
Radial Flow ◽  
Guide Vane ◽  
Low Pressure ◽  
Flow Distortion ◽  
Tip Leakage ◽  
High Pressure Compressor ◽  
Unsteady Rans ◽  
Last Stage ◽  
Flow Variables ◽  
Pressure Compressor

Abstract This paper uses Computational Fluid Dynamics to investigate the effect of an engine handling bleed situated on the outer casing downstream of the last rotor stage of a low-pressure compressor and upstream of the outlet guide vane and S-shaped duct. The model, validated against existing experimental data, utilized an unsteady RANS solver incorporating a Reynolds stress closure to examine the unsteady component interactions. The results showed that at bleed rates less than 25% of the mainstream flow the bleed effects were negligible. However, at higher bleed rates performance was significantly degraded. A uniform flow extraction hypothesis was employed to separate the positional bias effects from the bulk flow diffusion. This revealed that the bleed-induced radial flow distortion can significantly affect the OGV loading distribution, which thereby dictates the position and type of stall within the OGV passage. Extraction of the rotor tip leakage via the shroud bleed, combined with the radial flow distortion, contributed to a 28% reduction in duct loss at 10% bleed and up to 50% reduced loss at 25% bleed. The actual amount of flow required to be extracted for an OGV stall to develop, was 30%. That was independent of the bleed location and the type of stall. For bleeds up to 20%, the S-duct displayed a remarkable resilience and consistency of flow variables at duct exit. However, a stalled OGV deteriorated the radial flow uniformity that was presented to the high-pressure compressor.

Damage Analysis for Last-Stage Blade of Low-Pressure Turbine

2013 ◽  
Vol 37 (12) ◽  
pp. 1153-1157 ◽  
Author(s):  
Gee Wook Song ◽  
Woo Sung Choi ◽  
Wanjae Kim ◽  
Nam Gun Jung
Keyword(s):  
Low Pressure ◽  
Damage Analysis ◽  
Low Pressure Turbine ◽  
Last Stage

scholarly journals Study on water erosion simulation of low pressure last stage blade of nuclear steam turbine

2019 ◽  
Vol 504 ◽  
pp. 012057
Author(s):  
T J Wang ◽  
S S Wang ◽  
Y B Pei ◽  
J Di ◽  
J W Wang ◽  
...  
Keyword(s):  
Steam Turbine ◽  
Low Pressure ◽  
Water Erosion ◽  
Last Stage

An Experimental Investigation of the Influence of Flash-Back Flow on Last Three Stages of Low Pressure Steam Turbines

2014 ◽  
Author(s):  
Naoki Shibukawa ◽  
Yoshifumi Iwasaki ◽  
Yoshiaki Takada ◽  
Itaru Murakami ◽  
Takashi Suzuki ◽  
...  
Keyword(s):  
Reverse Flow ◽  
Flow Region ◽  
Low Pressure ◽  
Detailed Examination ◽  
Steam Turbines ◽  
Back Flow ◽  
Large Size ◽  
Vibration Stress ◽  
Last Stage ◽  
Two Stages

A shutdown operation of a large size steam turbine could possibly cause flashing phenomena of the pooled drain water in low-pressure heaters. The boiled steam is sometimes in the same amount as the main flow in the case where shutdown is executed during low load conditions, and returns to the steam flow path through the extraction lines. A series of experimental work with a subscale model turbine facility has been carried out to investigate the vibration stress behavior, and the steady and unsteady pressures under the flashing back conditions. It was observed that the blades of the two stages before the last stage (L-2) and a stage before the last stage (L-1) presented their peak vibration stresses immediately after the flash-back flow reached the turbine. In the meantime, the vibration stresses of the last stage (L-0) blades were reduced for a few tens of seconds. It can be thought that the flash-back flow pushed out the reverse flow region around the L-0 blades and allow the blades to be more stable. A detailed examination with measured data of the L-2 blade explained that, as long as the flash-back flow has small wetness, the blade is excited in its specific vibration modes in larger than 8th harmonic of rotational speed, but once the flash back flow carries water droplets, the fluid force in random frequencies remarkably increases and excites the blade in less than 7th harmonic range.

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