Start-Up Optimization of a CCGT Power Station Using Model Based Gas Turbine Control

2018 ◽  
Author(s):  
Alessandro Nannarone ◽  
Sikke A. Klein
Keyword(s):  
Steam Turbine ◽  
Gas Turbine ◽  
Optimization Model ◽  
Feedback Loop ◽  
Combined Cycle ◽  
Process Data ◽  
Power Station ◽  
Power Stations ◽  
Start Up ◽  
Steam Cycle

The rapid growth of renewable generation and its intermittent nature has modified the role of combined cycle power stations in the energy industry, and the key feature for the operational excellence is now flexibility. Especially, the capability to start an installation quickly and efficiently after a shutdown period leads to lower operational cost and a higher capacity factor. However, most of existing thermal power stations worldwide are designed for continuous operation, with no special focus on an efficient start-up process. In most current start-up procedures, the gas turbine controls ensure maximum heat flow to the heat recovery steam generator, without feedback from the steam cycle. The steam cycle start-up controls work independently with as main control parameter the limitation of the thermal stresses in the steam turbine rotor. In this paper, a novel start-up procedure of an existing combined cycle power station is presented, and it uses a feedback loop between the steam turbine, the boiler and the gas turbine start-up controls. This feedback loop ensures that the steam turbine can be started up with a significant reduction in stresses. To devise and assess this start-up methodology, a flexible and accurate dynamic model was implemented in the Simulink™ environment. It contains more than 100 component blocks (heat exchangers, valves, meters and sensors, turbines, controls, etc.), and the mathematical component sub-models are based on physical models and experimental correlations. This makes the model generally applicable to other power plant installations. The model was validated against process data related to the three start-up types (cold start, warm start, hot start). On this basis, the optimization model is implemented with feedback loops that control for example the exit temperature of the gas turbine based on the actual steam turbine housing temperature, resulting in a smoother heating up of the steam turbine. The optimization model was used to define the optimal inlet guide vanes position and gas turbine power output curves for the three types of start-up. These curves were used during real power station start-ups, leading to, for cold and warm starts, reductions in the start-up time of respectively 32.5% and 31.8%, and reductions in the fuel consumption of respectively 47.0% and 32.4%. A reduction of the thermal stress in the steam turbines is also achieved, thanks to the new start-up strategy.

Start-Up Optimization of a CCGT Power Station Using Model-Based Gas Turbine Control

2018 ◽  
Vol 141 (4) ◽  
Author(s):  
Alessandro Nannarone ◽  
Sikke A. Klein
Keyword(s):  
Steam Turbine ◽  
Gas Turbine ◽  
Optimization Model ◽  
Feedback Loop ◽  
Combined Cycle ◽  
Process Data ◽  
Power Station ◽  
Power Stations ◽  
Start Up ◽  
Steam Cycle

The rapid growth of renewable generation and its intermittent nature has modified the role of combined cycle power stations in the energy industry, and the key feature for the operational excellence is now flexibility. Especially, the capability to start an installation quickly and efficiently after a shutdown period leads to lower operational cost and a higher capacity factor. However, most of existing thermal power stations worldwide are designed for continuous operation, with no special focus on an efficient start-up process. In most current start-up procedures, the gas turbine controls ensure maximum heat flow to the heat recovery steam generator, without feedback from the steam cycle. The steam cycle start-up controls work independently with as main control parameter the limitation of the thermal stresses in the steam turbine rotor. In this paper, a novel start-up procedure of an existing combined cycle power station is presented, and it uses a feedback loop between the steam turbine, the boiler and the gas turbine start-up controls. This feedback loop ensures that the steam turbine can be started up with a significant reduction in stresses. To devise and assess this start-up methodology, a flexible and accurate dynamic model was implemented in the Simulink environment. It contains >100 component blocks (heat exchangers, valves, meters and sensors, turbines, controls, etc.), and the mathematical component submodels are based on physical models and experimental correlations. This makes the model generally applicable to other power plant installations. The model was validated against process data related to the three start-up types (cold start, warm start, hot start). On this basis, the optimization model is implemented with feedback loops that control, for example, the exit temperature of the gas turbine based on the actual steam turbine housing temperature, resulting in a smoother heating up of the steam turbine. The optimization model was used to define the optimal inlet guide vanes position and gas turbine power output curves for the three types of start-up. These curves were used during real power station start-ups, leading to, for cold and warm starts, reductions in the start-up time of, respectively, 32.5% and 31.8%, and reductions in the fuel consumption of, respectively, 47.0% and 32.4%. A reduction of the thermal stress in the steam turbines is also achieved, thanks to the new start-up strategy.

scholarly journals Technical and Economic Analysis of Repowering a Coal-Fired Power Plant

1999 ◽  
Author(s):  
Joseph Roy-Aikins ◽  
Reshleu J. Rampershad
Keyword(s):  
Economic Analysis ◽  
Steam Turbine ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Electrical Power ◽  
Economic Benefits ◽  
Combined Cycle ◽  
Economic Feasibility ◽  
Power Station ◽  
Power Stations

Owing to an abundance of coal reserves, about 92 percent of the electrical power produced in South Africa is generated in central power stations fired on cheaply priced coal. With a few power stations approaching the end of their design life, the question arises as to what to do with these outdated and inefficient plants. Retrofitting or repowering a station with gas turbines is one option being considered. As a case study, this paper investigates the technical and economic feasibility of repowering the Arnot power station to convert it to a combined cycle plant with increased capacity. This power station has six generating units, each of nominal capacity 350 MW and of average age 25 years. Four are in service, and the others are in reserve storage. Several repowering options were considered and the proposed re-design is parallel repowering, where additional steam for a steam turbine is generated in a gas turbine heat recovery steam generator to supplement the steam generated in a coal-fired boiler. Since natural gas, the preferred fuel for gas turbines, is not readily available in the country, kerosene was used as gas turbine fuel. Consequently, the performance of the chosen gas turbine had to be re-evaluated. The output of each unit increased by 77 MW and the efficiency by 8 percentage points to 43 percent, after repowering. Repowering was feasible, technically. An economic analysis was required to determine the magnitude of the economic benefits of repowering, if any, and it turned out that the cost of electricity generated by the new technology was higher than that produced by the outgoing one. It was concluded, therefore, that repowering the steam turbine units with gas turbines fired on kerosene was uneconomical, for the performance level achieved.

Steam Turbine Driving Compressor for Gas-Steam Combined Cycle Power Plant

2009 ◽  
Author(s):  
Wancai Liu ◽  
Hui Zhang
Keyword(s):  
Power Generation ◽  
Power Plant ◽  
Steam Turbine ◽  
Gas Turbine ◽  
Combined Cycle ◽  
Thermodynamic Process ◽  
Combined Cycle Power Plant ◽  
Steam Cycle

Gas turbine is widely applied in power-generation field, especially combined gas-steam cycle. In this paper, the new scheme of steam turbine driving compressor is investigated aiming at the gas-steam combined cycle power plant. Under calculating the thermodynamic process, the new scheme is compared with the scheme of conventional gas-steam combined cycle, pointing its main merits and shortcomings. At the same time, two improved schemes of steam turbine driving compressor are discussed.

scholarly journals Mechanical and Process Design of the Flevo Power Station Conversion Project

1989 ◽  
Author(s):  
J. Feenstra ◽  
P. Kamminga
Keyword(s):  
The Netherlands ◽  
Gas Turbine ◽  
Process Design ◽  
Gas Turbines ◽  
Combined Cycle ◽  
Power Station ◽  
Power Stations ◽  
The North

EPON operates a number of power stations in the north of the Netherlands. At some of these the forced-draught-fans have been replaced by gas turbines. Unit 3 of Flevo Power Station was the latest repowering project in the Netherlands. This paper gives a description of the most important points of the mechanical, and process design of the combined cycle unit and the influence of the gas turbine on the starting procedure.

An Integrated Steam/Gas Turbine-Generator for Combined-Cycle Applications

1989 ◽  
Author(s):  
J. H. Moore
Keyword(s):  
Steam Turbine ◽  
Gas Turbine ◽  
Power Plants ◽  
Combined Cycle ◽  
Gas Temperature ◽  
Turbine Generator ◽  
Fully Integrated ◽  
Reheat Steam ◽  
Exhaust Gas Temperature ◽  
Steam Cycle

Combined-cycle power plants have been built with the gas turbine, steam turbine, and generator connected end-to-end to form a machine having a single shaft. To date, these plants have utilized a nonreheat steam cycle and a single-casing steam turbine of conventional design, connected to the collector end of the generator through a flexible shaft coupling. A new design has been developed for application of an advanced gas turbine of higher rating and higher firing temperature and exhaust gas temperature with a reheat steam cycle. The gas turbine and steam turbine are fully integrated mechanically, with solid shaft couplings and a common thrust bearing. This paper describes the new machine, with emphasis on the steam turbine section where the elimination of the flexible coupling created a number of unusual design requirements. Significant benefits in reduced cost and reduced complexity of design, operation, and maintenance are achieved as a result of the integration of the machine and its control and auxiliary systems.

The Application of Gas-Turbine Technique to Steam Power

1950 ◽  
Vol 162 (1) ◽  
pp. 209-238 ◽  
Author(s):  
J. F. Field
Keyword(s):  
High Temperature ◽  
Steam Turbine ◽  
Gas Turbine ◽  
Steam Power ◽  
Temperature Range ◽  
Power Stations ◽  
Lower Temperature Range ◽  
Lower Temperature ◽  
External Combustion ◽  
Steam Cycle

Early attempts to adapt the mechanism of the turbine to the air- or gas-engine were frustrated by the losses in the compressor, but in the last twenty years improvements in the efficiency of the latter, together with better high-temperature metals for the turbine, have enabled the gas turbine to approach the efficiency of the steam turbine. The gas turbine has to operate from a much higher temperature and with more effective high-temperature regeneration to achieve this. On the other hand it cannot utilize heat down to anything like the same lower temperature as steam power. Most regenerative gas-turbine cycles are therefore more efficient than the steam cycle at the upper temperature range, and less efficient at the lower temperature range. Now that the Rankine steam cycle has reached 1,000 deg. F., a given increment of temperature has much less effect on the steam turbine than on the gas turbine. The paper describes a condensing gas-turbine† cycle with external combustion, which utilizes orthodox gas-turbine and steam-turbine components in such a manner that the thermodynamic advantages of the two in the respective temperature ranges mentioned above are combined to give a higher thermal efficiency than either the steam or the gas turbine is capable of alone, and with the prospective ability to utilize almost any fuel. A great improvement may thus be made possible in the fuel economy of condensing steam power stations, steamship propulsion, and steam locomotives, and in the ratio of mechanical power to heat in combined power and process or district heat production. It may become commercially worth while, apart from the saving in coal, to eliminate a large proportion of condensing operation on land in the winter months. By integrating the fuel-using industries in this manner it should be possible to save at least fifty-million tons of coal per annum on the present aggregate output of power and heat, with a further saving of eleven-million tons of locomotive coal. This should enable the nation to afford much more liberal use of power and heat and thus achieve much greater production in transport and industry.

Parametric study on the performance of combined power plant of steam and gas turbines

2021 ◽  
pp. 1-18
Author(s):  
Mohammad Almajali ◽  
Omar Quran
Keyword(s):  
Steam Turbine ◽  
Gas Turbine ◽  
Thermal Efficiency ◽  
Parametric Study ◽  
Gas Turbines ◽  
Combined Cycle ◽  
Design Parameters ◽  
Pressure Steam ◽  
Reheat Steam ◽  
Steam Cycle

Abstract This paper deals with aspects of the combined power and power (CPP) plants. Such plants consist of two major parts; the steam turbine and gas turbine plants. This study investigates the efficiency of CPP under the effect of several factors. CPP plants can achieve the highest thermal efficiency obtained with turbomachinery up to date. In this cycle, the anticipated waste thermal energy of the exhaust of gas turbine is used to generate a high pressure steam to empower the steam turbine in the steam cycle. By systematically varying the main design parameters, their influence on the CPP plant can be revealed. A comprehensive parametric study was conducted to measure the influence of the main parameter of the gas and steam cycles on the performance of CPP. The results exhibit that the overall plant thermal efficiency is significantly greater than that of either the two turbines. Due to the high thermal efficiency, a significant reduction in the greenhouse effect can be achieved. It is found that regenerative steam cycle will reduce the overall efficiency of combined cycle. On the other hand, using reheat steam cycle in the CPP plant will lead to an increase in both the thermal efficiency of the plant and the dryness factor of steam at exit of the steam turbine.

Repowering a Steam Turbine-Generator Power Plant Through Heat Recovery Type Combined Cycle: Selection of the Cycle — A Case Study

1996 ◽  
Author(s):  
H. A. Bazzini
Keyword(s):  
Power Plant ◽  
Steam Turbine ◽  
Gas Turbine ◽  
Heat Rate ◽  
Combined Cycle ◽  
Feed Water ◽  
Turbine Generator ◽  
Water Heaters ◽  
Selection Of ◽  
Steam Cycle

Much of the steam-turbine based, power generating units all over the word are more than 30 years old now. Within a few years they will face the possibility of retirement from service and replacement. Nonetheless some of them are firm candidates for repowering, a technology able to improve plant efficiency, output and reliability at low costs. This paper summarizes a study performed to establish the feasibility to repower a 2 × 33 MW steam turbine power plant and the procedure followed until selection of the steam cycle more suitable to the project. The preferred solution is compared with direct replacement of the units by a new combined cycle. Various repowering options were reviewed to find “beat recovery” type repowering as the best solution. That well-known technology consists of replacing the steam generator by a gas turbine coupled to an HRSG, supplying steam to the existing steam turbine. Three “GT+HRSG+ST” arrangements were considered. Available gas turbine-generators — both industrial and aero-derivative type —, were surveyed for three power output ranges. Five “typical” gas turbine-generator classes were then selected. Steam flow raised at the HRSG, gross and net power generation, and heat exchanging surface area of the HRSG, were calculated for a broad range of usually applied, steam turbine throttle conditions. Both single pressure and double pressure steam cycles were considered, as well as supplemental fire and convenience of utilizing the existing feed water heaters. Balance of plant constraints were also reviewed. Estimates were developed for total investment, O&M costs, fuel expenses, and revenues. Results are shown through various graphics and tables. The route leading to the preferred solution is explained and a sensitivity analysis added to validate the selection. The preferred solution, consisting in a Class 130 gas turbine in arrangement 1–1–2, a dual-pressure HRSG and a steam cycle without feed-water heaters, win allow delivering 200 MW to the grid, with a heat rate of 7423 kJ/kW-hr. Investment was valued at $MM77.0, with an IRR of 15.3%. Those figures compare well with the option of installing a new GTCC unit: with a better heat rate but an investment valued at $MM97.5, its IRR will only be 12.4%.

Externally-Fired Combined Cycle Repowering of Existing Steam Plants

1993 ◽  
Author(s):  
Christian L. Vandervort ◽  
Mohammed R. Bary ◽  
Larry E. Stoddard ◽  
Steven T. Higgins
Keyword(s):  
Heat Exchanger ◽  
Steam Turbine ◽  
Gas Turbine ◽  
High Efficiency ◽  
Low Cost ◽  
Operating Experience ◽  
Capital Cost ◽  
Combined Cycle ◽  
Plant Design ◽  
Generating Capacity

The Externally-Fired Combined Cycle (EFCC) is an attractive emerging technology for powering high efficiency combined gas and steam turbine cycles with coal or other ash bearing fuels. The key near-term market for the EFCC is likely to be repowering of existing coal fueled power generation units. Repowering with an EFCC system offers utilities the ability to improve efficiency of existing plants by 25 to 60 percent, while doubling generating capacity. Repowering can be accomplished at a capital cost half that of a new facility of similar capacity. Furthermore, the EFCC concept does not require complex chemical processes, and is therefore very compatible with existing utility operating experience. In the EFCC, the heat input to the gas turbine is supplied indirectly through a ceramic heat exchanger. The heat exchanger, coupled with an atmospheric coal combustor and auxiliary components, replaces the conventional gas turbine combustor. Addition of a steam bottoming plant and exhaust cleanup system completes the combined cycle. A conceptual design has been developed for EFCC repowering of an existing reference plant which operates with a 48 MW steam turbine at a net plant efficiency of 25 percent. The repowered plant design uses a General Electric LM6000 gas turbine package in the EFCC power island. Topping the existing steam plant with the coal fueled EFCC improves efficiency to nearly 40 percent. The capital cost of this upgrade is 1,090/kW. When combined with the high efficiency, the low cost of coal, and low operation and maintenance costs, the resulting cost of electricity is competitive for base load generation.

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