Coal-Derived Gas Utilization in Combined Gas-Steam Cycle Power Plants

Author(s):  
R. Tuccillo ◽  
G. Fontana ◽  
E. Jannelli

In this paper, a general analysis of combined gas-steam cycles for power plants firing with both hydrocarbons and coal derived gas is reported. The purpose of this paper is to study the influence on power plants performance of different kind of fuels and to evaluate the most significant parameters of both gas and combined cycle. Results are presented for plant overall efficiency and net specific work, steam to gas mass flow ratio, dimensionless gas turbine specific speed and diameter, CO2 emissions etc., as functions of gas cycle pressure ratio and of the combustion temperature. Furthermore, for an existing power plant with a 120 MW gas turbine, the authors try to establish in which measure the combined cycle characteristic parameters, the gas turbine operating conditions, and the heat recovery steam generator efficiency, are modified by using synthetic fuels of different composition and calorific value. The influence is also analyzed either of bottoming steam cycle saturation pressure or — in a dual pressure steam cycle — of dimensionless fraction of steam mass flow in high pressure stream. The acquired results seem to constitute useful information on the criteria for the optimal design of a new integrated coal gasification combined cycle (IGCC) power plant.

2018 ◽  
Vol 3 (7) ◽  
pp. 50
Author(s):  
Anthony Kpegele Le-ol ◽  
Sidum Adumene ◽  
Kenneth Israel

This work presents a comparative analysis of the thermo-economic performance of a simple, retrofitted and built-in combined cycle power plants within the Delta. The data were obtained from a 25MW gas turbine plant-based engine, retrofitted and MATLAB software was used to model the thermodynamic performance of the plants. The economic prediction of the plants was done using a developed net present value(NPV), internal rate of return (IRR), cost of investment (COR) and payback period (PBP).  The economic concept for plants performance was analysed under uncertainty constraints of energy need, operating conditions, energy cost and energy supply variability. Three plants configuration; simple gas turbine (SGT), retrofitted combined cycle (RCC) and Built-in combined cycle (BCC) was analysed based on these economic performance indicators. The three configurations show a positive NPV, PBP and IRR, with the BCC showing the optimum return on investment. Although the RCC show minimum initial cost on investment compare to BCC, the BCC demonstrates greater overall return with an NPV of $30,755,454.18, IRR of 17.1% and PBP of 6.3years for the period of 20years. The analysis shows cash flow of 34.1% and 52.6% for the RCC and BCC respectively. The result also showed that the plant performs better at a lower ambient temperature and higher relative humidity with a higher return on investment. This research provides great insight into the thermo-economic analysis, and benefits of combined cycle power plant and will aid energy system investors on the choice of the power plant for power generation in the Niger Delta.


Author(s):  
P. Shukla ◽  
M. Izadi ◽  
P. Marzocca ◽  
D. K. Aidun

The objective of this paper is to evaluate methods to increase the efficiency of a gas turbine power plant. Advanced intercooled gas turbine power plants are quite efficient, efficiency reaching about 47%. The efficiency could be further increased by recovering wasted heat. The system under consideration includes an intercooled gas turbine. The heat is being wasted in the intercooler and a temperature drop happens at the exhaust. For the current system it will be shown that combining the gas cycle with steam cycle and removing the intercooler will increase the efficiency of the combined cycle power plant up to 60%. In combined cycles the efficiency depends greatly on the exhaust temperature of the gas turbine and the higher gas temperature leads to the higher efficiency of the steam cycle. The analysis shows that the latest gas turbines with the intercooler can be employed more efficiently in a combined cycle power application if the intercooler is removed from the system.


1980 ◽  
Author(s):  
P. B. Roberts ◽  
T. E. Duffy ◽  
H. Schreiber

Two combustion turbine combined cycle power plants have been studied for performance and operating economics. Both power plants are in the size range that will be suitable for small utility application and use less than 106 GJ/hr (100 million Btu/hr). The Powerplant and Industrial Fuel Use Act of 1978 has exempted power plants of this size from the requirement to use coal. The first power plant is based on the Solar Turbines International (STI) Mars industrial gas turbine. The combined gas turbine/steam cycle is direct fired with No. 2 diesel fuel. A net plant efficiency of 39.7 percent (HHV) is obtained at the 11.56-mW growth rating of the Mars engine for a turbine rotor inlet temperature of 1331 K (1935 F). A total installed cost for the system is estimated to be within the band 545 to 660 $/kW. The second power plant is based on STI’s Centaur industrial gas turbine. The combined gas turbine/steam cycle is indirectly fired with solid fuel although it is intended that the installation can be initially fired with a liquid fuel. A net plant efficiency of 25.0 percent (HHV) is obtained burning Illinois No. 6 coal at a rating of 3.78 mW with a turbine inlet gas temperature of 1117 K (1550 F).


Author(s):  
Wancai Liu ◽  
Hui Zhang

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.


2015 ◽  
Vol 5 (2) ◽  
pp. 89
Author(s):  
Munzer S. Y. Ebaid ◽  
Qusai Z. Al-hamdan

<p class="1Body">Several modifications have been made to the simple gas turbine cycle in order to increase its thermal efficiency but within the thermal and mechanical stress constrain, the efficiency still ranges between 38 and 42%. The concept of using combined cycle power or CPP plant would be more attractive in hot countries than the combined heat and power or CHP plant. The current work deals with the performance of different configurations of the gas turbine engine operating as a part of the combined cycle power plant. The results showed that the maximum CPP cycle efficiency would be at a point for which the gas turbine cycle would have neither its maximum efficiency nor its maximum specific work output. It has been shown that supplementary heating or gas turbine reheating would decrease the CPP cycle efficiency; hence, it could only be justified at low gas turbine inlet temperatures. Also it has been shown that although gas turbine intercooling would enhance the performance of the gas turbine cycle, it would have only a slight effect on the CPP cycle performance.</p>


2019 ◽  
Vol 23 (Suppl. 4) ◽  
pp. 1187-1197 ◽  
Author(s):  
Marek Jaszczur ◽  
Michal Dudek ◽  
Zygmunt Kolenda

One of the most advanced and most effective technology for electricity generation nowadays based on a gas turbine combined cycle. This technology uses natural gas, synthesis gas from the coal gasification or crude oil processing products as the energy carriers but at the same time, gas turbine combined cycle emits SO2, NOx, and CO2 to the environment. In this paper, a thermodynamic analysis of environmentally friendly, high temperature gas nuclear reactor system coupled with gas turbine combined cycle technology has been investigated. The analysed system is one of the most advanced concepts and allows us to produce electricity with the higher thermal efficiency than could be offered by any currently existing nuclear power plant technology. The results show that it is possible to achieve thermal efficiency higher than 50% what is not only more than could be produced by any modern nuclear plant but it is also more than could be offered by traditional (coal or lignite) power plant.


Author(s):  
Alberto Vannoni ◽  
Andrea Giugno ◽  
Alessandro Sorce

Abstract Renewable energy penetration is growing, due to the target of greenhouse-gas-emission reduction, even though fossil fuel-based technologies are still necessary in the current energy market scenario to provide reliable back-up power to stabilize the grid. Nevertheless, currently, an investment in such a kind of power plant might not be profitable enough, since some energy policies have led to a general decrease of both the average price of electricity and its variability; moreover, in several countries negative prices are reached on some sunny or windy days. Within this context, Combined Heat and Power systems appear not just as a fuel-efficient way to fulfill local thermal demand, but also as a sustainable way to maintain installed capacity able to support electricity grid reliability. Innovative solutions to increase both the efficiency and flexibility of those power plants, as well as careful evaluations of the economic context, are essential to ensure the sustainability of the economic investment in a fast-paced changing energy field. This study aims to evaluate the economic viability and environmental impact of an integrated solution of a cogenerative combined cycle gas turbine power plant with a flue gas condensing heat pump. Considering capital expenditure, heat demand, electricity price and its fluctuations during the whole system life, the sustainability of the investment is evaluated taking into account the uncertainties of economic scenarios and benchmarked against the integration of a cogenerative combined cycle gas turbine power plant with a Heat-Only Boiler.


2010 ◽  
Vol 132 (12) ◽  
pp. 57-57
Author(s):  
Lee S. Langston

This article presents an overview of gas turbine combined cycle (CCGT) power plants. Modern CCGT power plants are producing electric power as high as half a gigawatt with thermal efficiencies approaching the 60% mark. In a CCGT power plant, the gas turbine is the key player, driving an electrical generator. Heat from the hot gas turbine exhaust is recovered in a heat recovery steam generator, to generate steam, which drives a steam turbine to generate more electrical power. Thus, it is a combined power plant burning one unit of fuel to supply two sources of electrical power. Most of these CCGT plants burn natural gas, which has the lowest carbon content of any other hydrocarbon fuel. Their near 60% thermal efficiencies lower fuel costs by almost half compared to other gas-fired power plants. Their installed capital cost is the lowest in the electric power industry. Moreover, environmental permits, necessary for new plant construction, are much easier to obtain for CCGT power plants.


Author(s):  
Rolf H. Kehlhofer

In the past 15 years the combined-cycle (gas/steam turbine) power plant has come into its own in the power generation market. Today, approximately 30 000 MW of power are already installed or being built as combined-cycle units. Combined-cycle plants are therefore a proven technology, showing not only impressive thermal efficiency ratings of up to 50 percent in theory, but also proving them in practice and everyday operation (1) (2). Combined-cycle installations can be used for many purposes. They range from power plants for power generation only, to cogeneration plants for district heating or combined cycles with maximum additional firing (3). The main obstacle to further expansion of the combined cycle principle is its lack of fuel flexibility. To this day, gas turbines are still limited to gaseous or liquid fuels. This paper shows a viable way to add a cheap solid fuel, coal, to the list. The plant system in question is a 2 × 150 MW combined-cycle plant of BBC Brown Boveri with integrated coal gasification plant of British Gas/Lurgi. The main point of interest is that all the individual components of the power plant described in this paper have proven their worth commercially. It is therefore not a pilot plant but a viable commercial proposition.


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