scholarly journals Energy Assessment of a Combined Cycle Power Plant through Empirical and Computational Approaches: A Case Study

2021 ◽  
Vol 12 (1) ◽  
pp. 25
Author(s):  
Waseem Amjad ◽  
Mubeen Shahid ◽  
Anjum Munir ◽  
Furqan Asghar ◽  
Owais Manzoor
Keyword(s):  
Steam Turbine ◽  
Energy Management ◽  
Gas Turbines ◽  
Power Plants ◽  
Management Practice ◽  
Simulation Software ◽  
Combined Cycle ◽  
Energy Audit ◽  
Significant Information ◽  
Turbine Efficiency

Energy management on the demand side is an important practice through which to address the challenge of energy shortage. In Pakistan, power plants have no specific energy management practice and a detail energy audit is normally observed as a one-time estimation that does not give significant information. In this study, an energy audit of a combined-cycle gas turbine power station was conducted and empirical data were compared with those obtained through a model developed in ASPEN, a simulation software that forecasts process performance. Next, an optimization tool was used to modify the ASPEN results and a comparison was drawn to estimate the amount of energy saved. It was found that compressor power consumption can be decreased up to 14.68% by increasing the temperature of compressed air from 320.2 °C to 423.79 °C for gas turbines. The output of gas turbines can be enhanced up to 13.5% and 21.4% with modelled and optimized data, respectively, using a multistage air compressor and multistage expansion. The calculated efficiency of the steam turbine was found to be 30.4%, which is 27.61% less than that of its designed efficiency. Steam turbine efficiency can be increased by 5% using a variable-speed water pump, leading to an estimated energy-saving potential of 8–9%. The combustion efficiency of gas turbines is not only important for higher turbine power output but also for better steam generation through heat-recovery steam generators in case of combined-cycle operations. The overall steam turbine efficiency is estimated to have increased by 19.27%, leading to a 12.68% improvement in combined efficiency.

Design of Fast and Reliable Steam Surface Condensers

2020 ◽  
Author(s):  
Ranga Nadig
Keyword(s):  
Steam Turbine ◽  
Gas Turbines ◽  
Power Plants ◽  
Combined Cycle ◽  
Design Features ◽  
Surface Condenser ◽  
Combined Cycle Plant ◽  
Startup Time ◽  
On Line ◽  
To Come

Abstract Power plants operating in cyclic mode, standby mode or as back up to solar and wind generating assets are required to come on line on short notice. Simple cycle power plants employing gas turbines are being designed to come on line within 10–15 minutes. Combined cycle plants with heat recovery steam generators and steam turbines take longer to come on line. The components of a combined cycle plant, such as the HRSG, steam turbine, steam surface condenser, cooling tower, circulating water pumps and condensate pumps, are being designed to operate in unison and come on line expeditiously. Major components, such as the HRSG, steam turbine and associated steam piping, dictate how fast the combined cycle plant can come on line. The temperature ramp rates are the prime drivers that govern the startup time. Steam surface condenser and associated auxiliaries impact the startup time to a lesser extent. This paper discusses the design features that could be included in the steam surface condenser and associated auxiliaries to permit quick startup and reliable operation. Additional design features that could be implemented to withstand the demanding needs of cyclic operation are highlighted.

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.

Effects of Steam Reheat in Advanced Steam Injected Gas Turbine Cycles

1998 ◽  
Author(s):  
A. Hofstädter ◽  
H. U. Frutschi ◽  
H. Haselbacher
Keyword(s):  
Steam Turbine ◽  
Gas Turbine ◽  
Power Plants ◽  
Steam Injection ◽  
Combined Cycle ◽  
Back Pressure ◽  
Turbine Efficiency ◽  
Pressure Steam ◽  
Additional Improvement ◽  
Gas Turbine Exhaust

Steam injection is a well-known principle for increasing gas turbine efficiency by taking advantage of the relatively high gas turbine exhaust temperatures. Unfortunately, performance is not sufficiently improved compared with alternative bottoming cycles. However, previously investigated supplements to the STIG-principle — such as sequential combustion and consideration of a back pressure steam turbine — led to a remarkable increase in efficiency. The cycle presented in this paper includes a further improvement: The steam, which exits from the back pressure steam turbine at a rather low temperature, is no longer led directly into the combustion chamber. Instead, it reenters the boiler to be further superheated. This modification yields additional improvement of the thermal efficiency due to a significant reduction of fuel consumption. Taking into account the simpler design compared with combined-cycle power plants, the described type of an advanced STIG-cycle (A-STIG) could represent an interesting alternative regarding peak and medium load power plants.

scholarly journals Design and Operating Experiences With Gas Turbine Combined Cycle Units

1971 ◽  
Author(s):  
R. W. Jones ◽  
A. C. Shoults
Keyword(s):  
Steam Turbine ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Power Plants ◽  
Combined Cycle ◽  
Economic Factors ◽  
Chemical Company ◽  
Gas Turbine Exhaust ◽  
Selection Of ◽  
Turbine Exhaust

This paper presents details of three large gas turbine installations in the Freeport, Texas, power plants of the Dow Chemical Company. The general plant layout, integration of useful outputs, economic factors leading to the selection of these units, and experiences during startup and operation will be reviewed. All three units operate with supercharging fan, evaporative cooler, and static excitation. Two of the installations are nearly identical 32,000-kw gas turbines operating in a combined cycle with a supplementary fired 1,500,000-lb/hr boiler and a 50,000-kw noncondensing steam turbine. The other installation is a 43,000-kw gas turbine and a 20,000-kw starter-helper steam turbine on the same shaft. The gas turbine exhaust is used to supply heated feedwater for four existing boilers.

scholarly journals USE OF GAS TURBINES FOR COMBINED ENERGY PRODUCTION

2020 ◽  
Vol 47 (1) ◽  
pp. 8-18
Author(s):  
V. A. Bulanin
Keyword(s):  
Natural Gas ◽  
Steam Turbine ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Power Plants ◽  
Ad Hoc ◽  
Combined Cycle ◽  
New Energy ◽  
State Of Research ◽  
Cis Countries

Abstract. Aim. Despite the obvious expediency of their widespread implementation, gas turbine (GT) and combined cycle gas turbine (CCGT) plants were only used in limited quantities in the former USSR and CIS countries. Due to the exhaustion of possibilities to increase the fuel use efficiency and return on investment (ROI) in steam-turbine combined heat and power (CHP) plants, the development of GT and CCGT plants becomes an urgent problem. In current global practice, the primary fuel for gas turbines and combined cycle gas turbines is natural gas. However, until recently, there has been a lack of experience in the design, construction and operation of GT and CCGT plants in the CIS countries. Method. Due to the ad hoc nature of research in this area, it was necessary to systematise the results of existing studies and assess the state of research at the world level taking regional characteristics into account. Results. The article presents the main considerations and potential effectiveness of the use of gas turbines. Basic gas turbine construction schemes are investigated along with their techno-economic characteristics and an assessment of their comparative utility. Conclusion. Considering the widespread availability of natural gas, it is recommended that gas turbine and combined-cycle plants be installed as part of the process of technical re-equipment in the fuel and energy complex, industry, agriculture and municipal energy sectors as part of the design and construction of new energy sources in the light of positive world experience and the current level of development of gas turbine technologies. Ubiquitous implementation of gas turbine units in the centres supplying heat and electric loads will reduce the regional economy’s need for energy fuel and ensure an increase in energy capacity without the need to construct new complex and uneconomic steam turbine power plants. 

Performance Charateristics of Advanced Gas Turbine Cogeneration Power Plants

2005 ◽  
Author(s):  
Meherwan P. Boyce
Keyword(s):  
Steam Turbine ◽  
Gas Turbine ◽  
Firing Temperature ◽  
Gas Turbines ◽  
Heat Recovery ◽  
Power Plants ◽  
Pressure Ratio ◽  
Combined Cycle ◽  
Air Filter ◽  
Cycle Efficiency

The performance analysis of the new generation of Gas Turbines in combined cycle operation is complex and presents new problems, which have to be addressed. The new units operate at very high turbine firing temperatures. Thus variation in this firing temperature significantly affects the performance and life of the components in the hot section of the turbine. The compressor pressure ratio is high which leads to a very narrow operation margin, thus making the turbine very susceptible to compressor fouling. The turbines are also very sensitive to backpressure exerted on them by the heat recovery steam generators. The pressure drop through the air filter also results in major deterioration of the performance of the turbine. The performance of the combined cycle is also dependent on the steam turbine performance. The steam turbine is dependent on the pressure, temperature, and flow generated in the heat recovery steam generator, which in turn is dependent on the turbine firing temperature, and the air mass flow through the gas turbine. It is obvious that the entire system is very intertwined and that deterioration of one component will lead to off-design operation of other components, which in most cases leads to overall drop in cycle efficiency. Thus, determining component performance and efficiency is the key to determining overall cycle efficiency. Thermodynamic modeling of the plant with individual component analysis is not only extremely important in optimizing the overall performance of the plant but in also determining life cycle considerations.

Simulation of Producer Gas Fired Power Plants With Inlet Fog Cooling and Steam Injection

2006 ◽  
Author(s):  
Mun Roy Yap ◽  
Ting Wang
Keyword(s):  
Natural Gas ◽  
Steam Turbine ◽  
Gas Turbine ◽  
Power Output ◽  
Gas Turbines ◽  
Power Plants ◽  
Steam Injection ◽  
Combined Cycle ◽  
Producer Gas ◽  
Cycle Systems

Biomass can be converted to energy via direct combustion or thermo-chemical conversion to liquid or gas fuels. This study focuses on burning producer gases derived from gasifying biomass wastes to produce power. Since the producer gases are usually low calorific values (LCV), the power plants performance under various operating conditions has not yet been proven. In this study, system performance calculations are conducted for 5MWe power plants. The power plants considered include simple gas turbine systems, steam turbine systems, combined cycle systems, and steam injection gas turbine systems (STIG) using the producer gas with low calorific values at approximately 30% and 15% of the natural gas heating value (on a mass basis). The LCV fuels are shown to impose high back compressor pressure and produces increased power output due to increased fuel flow. Turbine nozzle throat area is adjusted to accommodate additional fuel flows to allow compressor operate within safety margin. The best performance occurs when the designed pressure ratio is maintained by widening nozzle openings, even though the TIT is reduced under this adjustment. Power augmentations under four different ambient conditions are calculated by employing gas turbine inlet fog cooling. Comparison between inlet fog cooling and steam injection using the same amount of water mass flow indicates that steam injection is less effective than inlet fog cooling in augmenting power output. Maximizing steam injection, at the expense of supplying the steam to the steam turbine, significantly reduces both the efficiency and the output power of the combined cycle. This study indicates that the performance of gas turbine and combined cycle systems fueled by the LCV fuels could be very different from the familiar behavior of natural gas fired systems. Care must be taken if on-shelf gas turbines are modified to burn LCV fuels.

Part-Load Operation of Combined Cycle Plants With and Without Supplementary Firing

1995 ◽  
Vol 117 (3) ◽  
pp. 475-483 ◽  
Author(s):  
P. J. Dechamps ◽  
N. Pirard ◽  
Ph. Mathieu
Keyword(s):  
Steam Turbine ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Heat Recovery ◽  
Power Plants ◽  
Combined Cycle ◽  
Steam Generators ◽  
Part Load ◽  
Inlet Guide Vanes ◽  
Steam Plant

The design point performance of combined cycle power plants has been steadily increasing, because of improvements both in the gas turbine technology and in the heat recovery technology, with multiple pressure heat recovery steam generators. The concern remains, however, that combined cycle power plants, like all installations based on gas turbines, have a rapid performance degradation when the load is reduced. In particular, it is well known that the efficiency degradation of a combined cycle is more rapid than that of a classical steam plant. This paper describes a methodology that can be used to evaluate the part-load performances of combined cycle units. Some examples are presented and discussed, covering multiple pressure arrangements, incorporating supplemental firing and possibly reheat. Some emphasis is put on the additional flexibility offered by the use of supplemental firing, in conjunction with schemes comprising more than one gas turbine per steam turbine. The influence of the gas turbine controls, like the use of variable inlet guide vanes in the compressor control, is also discussed.

Peterhead Power Station: Parallel Repowering Innovative Steam Turbine Enhancement

2002 ◽  
Author(s):  
Thomas Depolt ◽  
Edwin Gobrecht ◽  
Gu¨nter Musch
Keyword(s):  
Steam Turbine ◽  
Gas Turbines ◽  
Power Plants ◽  
Cooling System ◽  
Reverse Flow ◽  
Combined Cycle ◽  
Automation System ◽  
Essential Difference ◽  
Control Logic ◽  
Power Station

In the year 2000 one of Europe’s most flexible power stations was commissioned by the authors’ company. The existing fossil fired power station was modified by a “Parallel Repowering”. With that concept three gas turbines (GT) in combination with three heat recovery steam generators (HRSG) were tied-in additionally to the fired boiler. This concept is compelling especially for large steam power plants and offers more flexibility than “Full Repowering” in matching GTs with the existing steam turbine (ST). The key to maintaining reliability of the repowered unit is the ST modernisation. Plant operability enhancements provide the flexibility of the fired boiler and ST for load following and peaking purposes. The authors’ company was responsible for the complete conversion of the fossil fired power station into a modern combined cycle unit. This comprises the tie-in of new steam pipes, bypass stations and the upgrade of the steam turbine auxiliaries as well as the implementation of a new automation system parallel to the existing one. The “Parallel Repowering” offers a maximum of operation variations: •Conventional (Rakine cycle) mode. •Open cycle mode (only GT). •Combined cycle mode. •Hybrid mode. The non-OEM steam turbine needed to be modified for the combined cycle operation with GTs. The condenser load had to be kept as low as possible because of the existing condenser design. Auxiliary systems like the gland steam system and the drain system had to be modified for all different operating modes. Special design features, like the IP rotor cooling system and the flange heating system, had to be extended to operate under all circumstances. One essential difference to the existing operational mode is the necessity of a steam bypass operation. Existing cold reheat (CRH) piping is of carbon steel, so the ST needs to be started with an isolated HP cylinder. The following modifications for the HP turbine were necessary: •For the isolated HP cylinder operation non-return valves (NRV) were built into the CRH line at the HP turbine exhaust. •The HP cylinder will be automatically isolated by closure of the HP valves and the non-return valves in the CRH line, and the simultaneous opening of the HP vent line. •As no instrumentation was available for a reliable monitoring of the isolated operation, a controlled reverse flow from the CRH to the HP vent line was established. •The HP cylinder evacuation is controlled by a dedicated control logic.

Development of Steam Turbines for State of the Art Combined Cycle Power Plants (CCPP)

2012 ◽  
Author(s):  
Rainer Quinkertz ◽  
Simon Hecker
Keyword(s):  
Steam Turbine ◽  
Gas Turbines ◽  
Power Plants ◽  
Three Dimensional ◽  
Plant Evolution ◽  
Combined Cycle ◽  
Steam Turbines ◽  
Electricity Grid ◽  
Capital Costs ◽  
Intermediate Pressure

In order to reduce CO2 emissions, reduce capital costs and increase the percentage of renewable energy in the electricity grid, common drivers of fossil power plant evolution continue to be efficiency, increased electricity output and operating flexibility. For CCPP, the efficiency level has reached more than 60%. Besides new and updated gas turbine frames, an improved bottoming cycle also contributes to this achievement. Without increasing steam temperatures above 565°C, improving steam turbine inner efficiency and enhancing the cold end, the overall efficiency of >60% would not be feasible. Extensive thermodynamic optimization is required to determine steam temperatures and condenser pressures. In addition, from a design standpoint, an optimum product strategy has to be developed. In order to minimize risks with future designs, both the practical and theoretical experiences from both ultra super critical applications at coal-fired steam power plants as well as from the CCPP steam turbine fleet have to be incorporated. For advanced technologies and components appropriate validation programs have to be defined. This paper presents the approach being taking to develop steam turbines for CCPP with modern gas turbines and it also displays the operating results of the first unit. Operational validation included the thermal behaviour of the high and intermediate pressure parts, a new last stage blade for the low pressure turbine and a patented start-up procedure. In particular, the paper focuses on the validation of three dimensional CFD calculations of the high and intermediate pressure turbine.

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