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.

scholarly journals ANALISIS KINERJA TURBIN UAP UNIT 3 BERDASARKAN PERFORMANCE TEST DI UNIT PELAKSANA PT.PLN (PERSERO) PEMBANGKITAN ASAM-ASAM

JTAM ROTARY ◽  
2021 ◽  
Vol 3 (1) ◽  
pp. 95
Author(s):  
Kemas Ronand Mahaputra
Keyword(s):  
Performance Test ◽  
Heat Rate ◽  
Steam Pressure ◽  
Outlet Temperature ◽  
Steam Turbines ◽  
Turbine Efficiency ◽  
Rate Calculation ◽  
Temperature And Pressure ◽  
Main Steam ◽  
Unit Unit

This study purpose to determine the performance of steam turbines Unit 3 of PT.PLN (Persero) Pembangkitan Asam-asam by comparing the results of the data obtained by each performance test. This research was carried out by taking data performance tests in 2012, 2017, 2018 and 2019 and then processing the data and obtaining turbine heat rate values and average turbine efficiency then comparing the values obtained in each year. The data taken is obtained from the rendal operation of PT.PLN (Persero) Pembangkitan Asam-asam, data variables taken are load, main steam temperature inlet, main steam pressure inlet, HP heater feed outlet temperature, HP heater outlet pressure, main steam flow. Temperature and pressure obtained are then searched for enthalpy values. The data obtained to calculate the value of the turbine heat rate and turbine efficiency on average per time from each performance test then averages the value of the turbine heat rate and turbine efficiency each time the data collection performance test is then compared with the data each year.The calculation of the turbine heat rate uses the heat & mass balance method by measuring the value of the incoming and outgoing fluid differences and comparing the load obtained, the efficiency of the turbine is obtained by dividing the energy of 1 kW with a turbine heat rate then multiplying by 100%. The average turbine heat rate calculation result for each performance test which is on May 23, 2012 is 2,701, October 27, 2017 is 3,136, September 5, 2018 is 3,005, May 21, 2019 is 3,113. The average turbine efficiency value on May 23, 2012 is 37.02%, October 27 2017 is 31.39%, September 5 2018 is 33.28%, May 21, 2019 is 32.12%. The performance of PT PLN (Persero) Pembangkit Asam-asam Implementing Unit Unit 3 has decreased from 2012 to 2019 which is 4.9%

Coordinated Control of Gas and Steam Turbines for Efficient Fast Start-Up of Combined Cycle Power Plants

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Yasuhiro Yoshida ◽  
Kazunori Yamanaka ◽  
Atsushi Yamashita ◽  
Norihiro Iyanaga ◽  
Takuya Yoshida
Keyword(s):  
Thermal Stress ◽  
Steam Turbine ◽  
Gas Turbines ◽  
Power Plants ◽  
Thermal Stresses ◽  
Control Method ◽  
Coordinated Control ◽  
Combined Cycle ◽  
Steam Turbines ◽  
Start Up

In the fast start-up for combined cycle power plants (CCPP), the thermal stresses of the steam turbine rotor are generally controlled by the steam temperatures or flow rates by using gas turbines (GTs), steam turbines, and desuperheaters to avoid exceeding the thermal stress limits. However, this thermal stress sensitivity to steam temperatures and flow rates depends on the start-up sequence due to the relatively large time constants of the heat transfer response in the plant components. In this paper, a coordinated control method of gas turbines and steam turbine is proposed for thermal stress control, which takes into account the large time constants of the heat transfer response. The start-up processes are simulated in order to assess the effect of the coordinated control method. The simulation results of the plant start-ups after several different cool-down times show that the thermal stresses are stably controlled without exceeding the limits. In addition, the steam turbine start-up times are reduced by 22–28% compared with those of the cases where only steam turbine control is applied.

Thermal Modeling of a Solar Steam Turbine With a Focus on Start-Up Time Reduction

2011 ◽  
Author(s):  
James Spelling ◽  
Markus Jo¨cker ◽  
Andrew Martin
Keyword(s):  
Steam Turbine ◽  
Power Plants ◽  
Thermal Power ◽  
The Body ◽  
Average Error ◽  
Steam Turbines ◽  
Effective Measure ◽  
Start Up ◽  
Turbine Casing ◽  
Main Steam

Steam turbines in solar thermal power plants experience a much greater number of starts than those operating in base-load plants. In order to preserve the lifetime of the turbine whilst still allowing fast starts, it is of great interest to find ways to maintain the turbine temperature during idle periods. A dynamic model of a solar steam turbine has been elaborated, simulating both the heat conduction within the body and the heat exchange with the gland steam, main steam and the environment, allowing prediction of the temperatures within the turbine during off-design operation and standby. The model has been validated against 96h of measured data from the Andasol 1 power plant, giving an average error of 1.2% for key temperature measurements. The validated model was then used to evaluate a number of modifications that can be made to maintain the turbine temperature during idle periods. Heat blankets were shown to be the most effective measure for keeping the turbine casing warm, whereas increasing the gland steam temperature was most effective in maintaining the temperature of the rotor. By applying a combination of these measures the dispatchability of the turbine can be improved significantly: electrical output can be increased by up to 9.5% after a long cool-down and up to 9.8% after a short cool-down.

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.

Operational Improvements for Start-Up Time Reduction in Solar Steam Turbines

2014 ◽  
Author(s):  
Monika Topel ◽  
Magnus Genrup ◽  
Markus Jöcker ◽  
James Spelling ◽  
Björn Laumert
Keyword(s):  
Thermal Stresses ◽  
Steam Pressure ◽  
Back Pressure ◽  
Temperature Gradients ◽  
Steam Turbines ◽  
Transient Operation ◽  
Start Up ◽  
Time Reduction ◽  
Solar Resource ◽  
Turbine Model

Solar steam turbines are subject to high thermal stresses as a result of temperature gradients during transient operation, which occurs more frequently due to the variability of the solar resource. In order to increase the flexibility of the turbines while preserving lifing requirements, several operational modifications for maintaining turbine temperatures during offline periods are proposed and investigated. The modifications were implemented in a dynamic thermal turbine model and the potential improvements were quantified. The modifications studied included: increasing the gland steam pressure injected to the end-seals, increasing the back pressure and increasing the barring speed. These last two take advantage of the ventilation and friction work. The effects of the modifications were studied both individually as well as in different combinations. The temperatures obtained when applying the combined modifications were compared to regular turbine cool-down temperatures and showed significant improvements on the start-up times of the turbine.

Flexible and Economical Operation of Power Plants: 25 Years of Expertise

2012 ◽  
Author(s):  
Jan Greis ◽  
Edwin Gobrecht ◽  
Steffen Wendt
Keyword(s):  
Power Generation ◽  
Power Plant ◽  
Power Plants ◽  
Operating Experience ◽  
Life Time ◽  
Steam Turbines ◽  
Start Up ◽  
Hot Start ◽  
Fast Cooling ◽  
Short Time

Within the last years the idea of running a conventional power plant has changed. Fluctuating power generation by solar power and wind parks creates a need for highly flexible backup power plants. This need quickly arose within the last 5 years and the market is still searching for a solution. Single steam turbine manufacturers can provide features to react more flexibly, quickly and to prolong component life time. Thus, considerable operating experience has already been in existence for many years. New highly efficient steam turbines are already equipped with solutions to serve an ambitious market. But also, for existing units, different modernization packages can be provided along with hardware and software modifications which allow power plants to supply power at a moment’s notice. This paper presents the overall approach and the possible field of application for the well-established features of Siemens steam turbines. Starting a power plant within a short time to fill the gap of fluctuating power generation is an important capability in order to participate in today’s and tomorrow’s energy market. A fully automated start-up procedure to avoid any delays contributes in fulfilling this requirement. Optimized component geometries guarantee the shortest start-up times. Furthermore, a parallel start-up of gas and steam turbines (Hot Start on the Fly) has already been proven for many years. Regarding flexibility, the improvement of start-up time is only one major aspect. Another important task is to provide the opportunity to influence scheduled maintenance outages. Therefore, steam turbines can be equipped with software which allows the customer to plan the power plant’s outages in accordance with single components requirements, e.g. GT outages. The lifecycle counter enables customers to evaluate the optimum between start-up time and life time consumption based on dynamic equivalent operating hours. In addition, fast cooling procedures help to keep outage times to a minimum.

Operation and Maintenance Improvements of Steam Turbines Subject to Frequent Start by Rotor Stress Monitoring

2020 ◽  
Author(s):  
Federico Bucciarelli ◽  
Damaso Checcacci ◽  
Gabriele Girezzi ◽  
Annamaria Signorini
Keyword(s):  
Fatigue Damage ◽  
Thermal Stresses ◽  
Low Cycle Fatigue ◽  
Weather Conditions ◽  
Control Panel ◽  
Steam Turbines ◽  
Stress Monitoring ◽  
Warm Up ◽  
Start Up ◽  
Critical Components

Abstract Steam Turbines operating in Concentrated Solar Plants and Peaking Combined Cycles are subjected to daily thermal stresses, induced by start-ups and load variations, deeply affecting allowed production per day. The extent and number of such thermal stresses is largely depending on the capability, of both plant and operators, to smooth the variations in steam temperature and load resulting from both weather conditions (in CSPs) and grid demand. In this operating scenario, conservative simplified rules are normally applied to determine daily warm-up times duration at starts, to preserve critical components from Low Cycle Fatigue damage; the planned maintenance intervals, as well, have been typically defined on the basis of a specified number of starts and running hours. In this article, the application of an online Rotor Stress Monitoring (RSM) technology, installed in the Steam Turbine User Control Panel, is used to directly determine the fatigue damage cumulated by each Start-Up and variation in operating condition. The results of application of this technology, with respect to standard formulations, are shown for a specific Concentrated Solar Plant across an operating period of four years. It is shown how, using the RSM as a basis for either startup or maintenance scheduling, can result in optimization of start-up times and maintenance intervals both for new units and retro-fit. The applicability of rotor stress direct monitoring and life analysis to higher temperature services is also introduced.

Thermal Modeling of a Solar Steam Turbine With a Focus on Start-Up Time Reduction

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
James Spelling ◽  
Markus Jöcker ◽  
Andrew Martin
Keyword(s):  
Steam Turbine ◽  
Power Plants ◽  
Thermal Power ◽  
The Body ◽  
Average Error ◽  
Steam Turbines ◽  
Effective Measure ◽  
Start Up ◽  
Turbine Casing ◽  
Main Steam

Steam turbines in solar thermal power plants experience a much greater number of starts than those operating in baseload plants. In order to preserve the lifetime of the turbine while still allowing fast starts, it is of great interest to find ways to maintain the turbine temperature during idle periods. A dynamic model of a solar steam turbine has been elaborated, simulating both the heat conduction within the body and the heat exchange with the gland steam, main steam and the environment, allowing prediction of the temperatures within the turbine during off-design operation and standby. The model has been validated against 96 h of measured data from the Andasol 1 power plant, giving an average error of 1.2% for key temperature measurements. The validated model was then used to evaluate a number of modifications that can be made to maintain the turbine temperature during idle periods. Heat blankets were shown to be the most effective measure for keeping the turbine casing warm, whereas increasing the gland steam temperature was most effective in maintaining the temperature of the rotor. By applying a combination of these measures the dispatchability of the turbine can be improved significantly: electrical output can be increased by up to 9.5% after a long cooldown and up to 9.8% after a short cooldown.

Numerical Investigations of History Temperature Field and Stress Field of Main Steam Valve

2014 ◽  
Author(s):  
Sihua Xu ◽  
Zhiqiang Hu ◽  
Jin He ◽  
Lei Xiao ◽  
Puning Jiang
Keyword(s):  
Temperature Field ◽  
Thermal Stress ◽  
Stress Field ◽  
Control Valve ◽  
Steam Turbines ◽  
Functional Requirements ◽  
Computing Technique ◽  
Start Up ◽  
Actual Operation ◽  
Main Steam

The flexible start up stop, quick start have been considered as essential functional requirements in the development of new steam turbines. To develop a steam turbine with 566 °C live steam temperature, not only the flexible start up and stop, quick start function, but also the reasonable working life of units influenced by the transient thermal stress are going to be considered. The design of above factors faces challenge. On the other hand, benefited from improved computing technique and ability, it is possible to calculate history temperature field and thermal stress more accurate for each project-specific component. In this paper, certain supercritical unit inlet valve will be investigated. The valve has been operated for more than 6 years in certain power plant. Thermocouples are equipped in both stop valve chamber and control valve chamber at 100% wall depth to obtain actual operation data. According to the characteristics of different heat transfer stages, numerical analysis is performed to obtain accurate history temperature field and stress field using varied boundary conditions from the cold start at room temperature until the unit at full load.

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