Transient Loading Improvements for Large Steam-Electric Generating Units

1962 ◽  
Vol 84 (1) ◽  
pp. 9-20
Author(s):  
Charles Strohmeyer
Keyword(s):  
Operating Conditions ◽  
Steam Temperature ◽  
Turbine Generator ◽  
Supervisory System ◽  
Low Pressure Turbine ◽  
Start Up ◽  
Temperature And Pressure ◽  
Start Ups ◽  
Full Pressure ◽  
Turbine Exhaust

The intent of this paper is to discuss the ultimate in operating flexibility during transient conditions that can be built into new designs having steam conditions of 2400 psig, 1050/1000 F reheat or above. The following discussion proposes an over-all operating philosophy in the hope of developing better understanding among the engineers, operators, and equipment manufacturers. Emphasis is placed upon steam temperature control to suit various turbine operating conditions. New methods proposed include a means of raising throttle steam enthalpy during hot turbine starts, a control and/or supervisory system for regulating unit start-ups and shutdowns, and a new means of cooling the low pressure turbine exhaust during start-up. As a result, for short duration turbine generator shutdowns as 8 hours, units may be unloaded rapidly at full pressure and in some cases may be restarted from turning gear to one third load restoring design primary steam temperature and pressure in as little as 35 minutes without sacrifice of safety.

Single Process Plant Application of a Gas Turbine Generator With Recovery Boiler

1971 ◽  
Author(s):  
R. W. Klein
Keyword(s):  
Gas Turbine ◽  
Turbine Generator ◽  
Engineering Construction ◽  
Start Up ◽  
Process Plant ◽  
Single Process ◽  
Recovery Boiler ◽  
Gas Turbine Exhaust ◽  
Selection Of ◽  
Turbine Exhaust

This paper consists of the application considerations given for the selection of on-site power generation using a gas turbine with a recovery boiler in the process chemical industry. The additional use of 400 psig steam from recovery heat of the gas turbine exhaust used for process steam is evaluated. The techniques used for engineering, construction, training, and start-up are discussed. The performance of the unit after 30,000 operating hours, including reliability and a discussion of equipment problems, is included.

Computational Fluid Dynamics Analysis of a Steam Power Plant Low-Pressure Turbine Downward Exhaust Hood

1996 ◽  
Vol 118 (1) ◽  
pp. 214-224 ◽  
Author(s):  
R. H. Tindell ◽  
T. M. Alston ◽  
C. A. Sarro ◽  
G. C. Stegmann ◽  
L. Gray ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Integrated Approach ◽  
Low Pressure ◽  
Operating Conditions ◽  
Exhaust Hood ◽  
Steam Power ◽  
Low Pressure Turbine ◽  
Computational Fluid Dynamics Analysis ◽  
Turbine Exhaust

Computational fluid dynamics (CFD) methods are applied to the analysis of a low-pressure turbine exhaust hood at a typical steam power generating station. A Navier-Stokes solver, capable of modeling all the viscous terms, in a Reynolds-averaged formulation, was used. The work had two major goals. The first was to develop a comprehensive understanding of the complex three-dimensional flow fields that exist in the exhaust hood at representative operating conditions. The second was to evaluate the relative benefits of a flow guide modification to optimize performance at a selected operating condition. Also, the influence of simulated turbine discharge characteristics, relative to uniform hood entrance conditions, was evaluated. The calculations show several interesting and possibly unique results. They support use of an integrated approach to the design of turbine exhaust stage blading and hood geometry for optimum efficiency.

scholarly journals X-Ray Measurements in a Cavitating Centrifugal Pump During Fast Start-Ups

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
S. Duplaa ◽  
O. Coutier-Delgosha ◽  
A. Dazin ◽  
G. Bois
Keyword(s):  
Centrifugal Pump ◽  
Rocket Engine ◽  
Transient Behavior ◽  
Operating Conditions ◽  
Centrifugal Impeller ◽  
X Ray ◽  
Speed Increase ◽  
Start Up ◽  
Fast Start ◽  
Start Ups

The start-up of rocket engine turbopumps is generally performed in a few seconds or even less. It implies that these pumps reach their nominal operating conditions after a few rotations only. During the start-up, the flow evolution within the pump is governed by transient phenomena, based mainly on the flow rate and rotation speed increase. Significant pressure fluctuations, which may result in the development of cavitation, are observed. A centrifugal impeller whose transient behavior during start-ups has been detailed in a previous publication is considered. Three different cases of fast start-ups have been identified according the final operating point (Duplaa et al., 2010, “Experimental Study of a Cavitating Centrifugal Pump During Fast Start-Ups,” ASME J. Fluids Eng., 132(2), p. 021301). The aim of this paper is to analyze the evolution during the start-ups of the local amount of vapor in the blade to blade channels of the pump by fast X-ray imaging. This technique has enabled to calculate the time-evolution of the fluid density within the pump, which appears to be correlated with pressure time-evolutions. For each investigated start-up, X-ray measurements have been performed at three different sections of the impeller height. For each investigated start-up and section tested, measurements have been performed for several initial positions of the impeller, to estimate the measurement uncertainty, and to obtain records from different beam angles, like in tomography.

Changing Fossil Unit Startup Process Reduces Rotor Stresses

2008 ◽  
Author(s):  
Craig Jennings
Keyword(s):  
Thermal Stresses ◽  
Energy Market ◽  
Steam Turbines ◽  
Steam Temperature ◽  
Thermally Induced ◽  
Start Up ◽  
Hot Start ◽  
Startup Process ◽  
Temperature And Pressure ◽  
Main Steam

The changes in the energy market dispatching and pricing, have increased the need to start fossil steam turbines faster to meet demand and save fuel. Exelon worked with a consultant to optimize the start up times of their steam turbines resulting in greatly reduced start up times, increased dispatching frequency, and reduced thermal stresses on the turbines. This optimized start up process was achieved by utilization of the Valve Open Start (VOS) and Accelerated Hot Start (AHS) process. VOS utilizes condenser vacuum aligned to the steam generator to produce superheated steam at much lower temperatures and pressures than usual. This steam is drawn through the turbine to warm the unit while the boiler increases in temperature and pressure. The AHS changes the startup sequence of operations by setting up the turbine in a manner that allows the turbine to roll at precisely the time that a perfect temperature match is obtained between the main steam temperature and first stage metal temperature. The use of these processes significantly increases profitability of the units and meets all OEM criteria for unit protection and results in a reduction in rotor thermal gradient, temperature mismatch, and thermally induced vibration.

Applications Using Dry Gas Seals to Control Axial Shaft Loads in Centrifugal Compressors

1992 ◽  
Author(s):  
C. C. Bear ◽  
S. W. Gibson
Keyword(s):  
Control System ◽  
Operating Conditions ◽  
The Past ◽  
Axial Forces ◽  
Start Up ◽  
Beam Type ◽  
Gas Seals ◽  
And Control ◽  
Compressor Efficiency ◽  
Full Pressure

Dry gas seal technology has developed significantly over the past two decades. In addition to advances in standard seal technologies, alternate configurations of dry gas seals within the compressor have provided compressor efficiency improvements among other benefits. This paper describes the innovative application of dry gas seals in the reduction and control of axial shaft forces in pipeline gas compressors. By uniquely configuring the dry seals, the balance piston was removed from a beam type compressor, resulting in improvement of the compressor efficiency. In addition, the maximum axial forces in an overhung unit were substantially lowered, eliminating full pressure start-up problems, and allowing the practical installation of magnetic bearings. In both beam and overhung compressor applications, these dry seals combined with a control system reduce axial forces on the shaft to zero under most operating conditions.

El método Lean Startup. Cómo crear empresas de éxito utilizando la innovación continua de Eric Ries

2019 ◽  
Vol 1 (1) ◽  
pp. 83-88
Author(s):  
Ysmael Jesús Ayala Colqui
Keyword(s):  
A Priori ◽  
El Paso ◽  
Start Up ◽  
Start Ups ◽  
Lean Startup

Una start-up es definida como una empresa destinada solucionar problemas de maneras no obvias, donde el éxito no está garantizado de antemano y, solo en los casos de éxito efectivo, se adquiere un crecimiento rápido y significativo (Robehmed, 2013). Ejemplos clásicos de start-ups serían Facebook, Uber o AirBnB que, con comienzos modestos, pero con ideas innovadoras, se convirtieron con el paso del tiempo en empresas de ingresos millonarios. Una de las tantas preguntas al respecto sería la siguiente: ¿cómo lograr una start-up de éxito a sabiendas que el éxito no está garantizado a priori y, aún más, que la gran mayoría de estas fracasan?

Wer gewinnt den ‚War for Talent’: Konzerne oder Start-ups?

2015 ◽  
Vol 12 (4) ◽  
pp. 24-31 ◽  
Author(s):  
Rabea Laugemann ◽  
Christopher Buschow ◽  
Beate Schneider
Keyword(s):  
Start Up ◽  
Soziale Beziehungen ◽  
Start Ups ◽  
War For Talent

Im ‚War for Talent‘ konkurrieren heutzutage große Konzerne mit innovativen Start-ups um vielversprechenden Nachwuchs. Was bestimmt die Attraktivität von Arbeitgebern bei Medien- und Kommunikationsstudierenden? Diese Frage wird im Rahmen einer quantitativen Online-Befragung untersucht, vor allem im Hinblick darauf, ob Start-ups oder Konzerne als erste Arbeitgeber präferiert werden. Befragte, denen Prestige wichtig ist, bevorzugen eher Konzerne als Arbeitgeber. Wer Wert auf ein innovatives Arbeitsumfeld und soziale Beziehungen legt, entscheidet sich vermehrt für ein Start-up. Im Wettbewerb um die besten Köpfe sind damit junge Unternehmensgründungen inzwischen eine ernst zu nehmende Konkurrenz für Konzerne.

Cake Formation in Cross-Flow Microfiltration Systems

1992 ◽  
Vol 25 (10) ◽  
pp. 149-162 ◽  
Author(s):  
V. L. Pillay ◽  
C. A. Buckley
Keyword(s):  
Cross Flow ◽  
Operating Conditions ◽  
Waste Waters ◽  
Domestic Waste ◽  
Time Curve ◽  
Good Correspondence ◽  
Operating Variables ◽  
Start Up ◽  
Turbulent Flow Regime ◽  
Cake Formation

Cross-flow microfiltration (CFMF) has potentially wide application in the processing of industrial and domestic waste waters. Optimum design and operation of CFMF systems necessitates a knowledge of the characteristic system behaviour, and an understanding of the mechanisms governing this behaviour. This paper is a contribution towards the elucidation and understanding of the behaviour of a woven fibre CFMF operated in the turbulent flow regime. The characteristic flux-time curve and effects of operating variables on flux are presented for a limestone suspension cross-flow filtered in a 25 mm woven fibre tube. The phenomena contributing to the shape of the flux-time curve are discussed. A model of the mechanisms governing cake growth and limit is presented. Predicted steady-state fluxes show a notably good correspondence with experimentally measured values. It is also found that the flux may not be uniquely defined by the operating conditions, but may also be a function of the operating path taken to reach the operating point. This is of significance in the start-up and operation of CFMF units.

scholarly journals Innovation Capabilities and the Performance of Start-Ups in Korea: The Role of Government Support Policies

2021 ◽  
Vol 13 (11) ◽  
pp. 6009
Author(s):  
Se-Kyoung Choi ◽  
Sangyun Han ◽  
Kyu-Tae Kwak
Keyword(s):  
Firm Performance ◽  
Financial Support ◽  
Political Support ◽  
Sustainable Growth ◽  
Government Support ◽  
Role Of Government ◽  
Positive Effects ◽  
Start Up ◽  
Start Ups

What kind of capacity is needed to improve the performance of start-ups? How effective are government support policies in improving start-up performance? Start-ups are critical firm group for ensuring the prospective and sustainable growth of an economy, and thus many countries’ governments have established support policies and they are likely to engage more widely in forward-looking political support activities to ensure further growth and expansion. In this paper, the effect of innovation capabilities and government support policies on start-up performance is examined. We used an unbalanced panel data analysis with a random effect generalized least squares. We investigated the effect of government support policies on 4368 Korean start-ups. The findings indicated that technology and knowledge capabilities had positive effects on the sales performance of start-ups, and government financial support positively affected the relationship between knowledge capability and firm performance. However, when government financial support increased, marketing capability was negatively associated with firm performance. These results demonstrate the significant role of government financial support, including its crowding in but also its crowding out effect. Practical implications: To be more effective, governments should employ innovation-driven entrepreneurship policy approaches to support start-ups. To improve their performance, start-ups need to increase their technology and knowledge capabilities. This study extends recent efforts to understand more fully the effect of government support policies on start-ups differing in their technology, knowledge, and marketing capabilities.

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