Turbine Combined Cycle Research Articles

열회수증기발생기 해석방법을 개선한 가스터빈 복합발전 성능해석 프로그램 개발

Accurate prediction of off-design performance is an important task in the design stage of gas turbine combined cycle (GTCC) power plants, and commercial software is generally used for that purpose. Most commercial software is easy to use in general but is hard to use effectively to guarantee a high accuracy because the mathematical models are very simple or not easy to be tuned to specific purposes. In the GTCC analysis, the analysis of the heat recovery steam generator (HRSG) is the major source of simulation uncertainty. To overcome the problem, a GTCC analysis program was developed, focusing on enhancing the convenience and versatility of the HRSG analysis. The program was coded with the Excel Visual Basic for applications (VBA). The program was validated through comparison with reference data. The maximum deviation from the reference data was 0.27% in the design calculation and 3.26% in the off-design calculation, which are lower in comparison to commercial software.

Design and performance evaluation of a novel hybrid solar-gas power and ORC-based hydrogen-production system

This study proposes a novel hybrid solar-gas power and hydrogen-production (SGPH) system, which is comprised by the parabolic trough solar thermal system, gas-steam turbine combined cycle (GTCC) and organic Rankine cycle-based hydrogen-production system. Based on the Ebsilon code, the operation processes of the SGPH system are simulated. The results show that the output power and electric efficiency of the SGPH system are 102.0 MW and 44.2%, and the daily hydrogen output is 172.4 kg. The annual operation simulation results reveal that the GTCC and solar island can both achieve stable operations, and the power generation section and hydrogen-production device can both work effectively, which means the SGPH system can follow the pre-set operation strategy. According to the economic analysis results, the levelized electricity costs of the SGPH system with and without considering the subsidy are 0.052 $/kWh and 0.077 $/kWh, and the levelized hydrogen cost of the SGPH system is 5.72 $/kg, which reveal a relatively good economic competitiveness. The pollutant emission reduction analysis results show that compared with a coal-fired power system, the SGPH system can reduce the emission quantities of CO2, NOx, SO2 and dust by 103022.9 t, 3343.6 t, 3161.2 t and 1724.8 t every year.

Techno-economic analysis of cascaded supercritical carbon dioxide combined cycles for exhaust heat recovery of typical gas turbines

Gas turbine combined cycle is widely used to achieve power balance in grids with uncertain renewable energy sources. To further enhance the rapid load-change capability of combined cycle plants, supercritical carbon dioxide (CO2) has been considered an alternative working fluid for the bottoming cycle. This paper presents a techno-economic investigation of a cascaded supercritical carbon dioxide cycle for typical gas turbines. This cascaded supercritical carbon dioxide cycle consists of a supercritical CO2 cycle and a transcritical CO2 cycle. A solving procedure is originally proposed to compare and optimize the combined cycles in eight gas turbines, whose power output and exhaust temperature ranges were 1.24–113.95 MW and 583–896 K, respectively. The results show that the cascaded supercritical CO2 combined cycle is thermodynamically favorable for small-scale gas turbines with high exhaust temperatures. The variations in the levelized cost of electricity indicate that the combined cycle with a small-scale gas turbine is more sensitive to the operation conditions of the bottoming supercritical CO2 cycle. Regarding the QD128 gas turbine (11.50 MW and 760 K) combined cycle, its multi-objective optimization results show that the optimal solution for techno-economic performance corresponds to a levelized cost of electricity of 0.0420 $/kWh and a net power of 19.701 MW. These findings also suggest that the cascaded supercritical CO2 combined cycle is a viable option for large-scale gas turbines.

Proposed Solution for Adaptation of the Block in TPP Bitola using Gas Turbine Combined Cycle

The subject of this paper is to present the possibility of adapting the existing conventional steam power station of TPP Bitola (Republic of North Macedonia) in a plant using gas turbine combined cycle (GTCC). The main emphasis is placed on the energy analysis of the conceptual plant where the required energy parameters of the individual components of the combined cycle are shown. The parameters of the superheated steam delivered by the boiler in the current operating mode are considered and they should be provided by heat recovery steam generator with the heat of the exhaust gases from the gas turbine to achieve a high degree of adjusted upgrade of the thermal power plant. Simplified schemes of the envisaged combined cycle consisting of two gas turbines and one steam turbine are given. A comparative analysis of the efficiency and capacity of the existing and conceptual plant is performed.

Problems of acoustic safety in power engineering

Environmental safety issues are becoming increasingly important in the life of society. Among environmental safety issues in power engineering, acoustic safety occupies a special place. The problem of acoustic safety is associated with the fact that the regular operation of power equipment leads to an increased noise level, and power facilities are located in close proximity to residential areas. In this work, acoustic calculations were performed to determine the sanitary protection zone for gas turbines units (GTU) and combined cycle gas turbine units (CCGT) of various capacities. A formula was obtained for calculating the width of the sanitary protection zone depending on the capacity of gas turbine units and combined cycle plants and their number. It is shown that the sanitary protection zone (SPZ) of a power unit of high capacity is smaller than the sanitary protection zone of several power units of the same capacity. It is found that the noise levels from individual groups of equipment can determine the noise level at the entire border of the sanitary protection zone or in its individual sections. At the same time, noise suppression measures should be taken for all sources that generate noise levels in excess of standards. It is necessary to start noise suppression measures from those sources that generate excess noise in a larger section of the sanitary protection zone.

A Hybrid Solar-Gas Turbine Combined-Cycle with Absorption Inlet-Air Cooling as a Decarbonizing and Power Boosting Solution: Energy and Environment Analyses

A Hybrid Solar-Gas Turbine Combined-Cycle with Absorption Inlet-Air Cooling as a Decarbonizing and Power Boosting Solution: Energy and Environment Analyses

A Comparative Feasibility Study of the Use of Hydrogen Produced from Surplus Wind Power for a Gas Turbine Combined Cycle Power Plant

Because of the increasing challenges raised by climate change, power generation from renewable energy sources is steadily increasing to reduce greenhouse gas emissions, especially CO2. However, this has escalated concerns about the instability of the power grid and surplus power generated because of the intermittent power output of renewable energy. To resolve these issues, this study investigates two technical options that integrate a power-to-gas (PtG) process using surplus wind power and the gas turbine combined cycle (GTCC). In the first option, hydrogen produced using a power-to-hydrogen (PtH) process is directly used as fuel for the GTCC. In the second, hydrogen from the PtH process is converted into synthetic natural gas by capturing carbon dioxide from the GTCC exhaust, which is used as fuel for the GTCC. An annual operational analysis of a 420-MW-class GTCC was conducted, which shows that the CO2 emissions of the GTCC-PtH and GTCC-PtM plants could be reduced by 95.5% and 89.7%, respectively, in comparison to a conventional GTCC plant. An economic analysis was performed to evaluate the economic feasibility of the two plants using the projected cost data for the year 2030, which showed that the GTCC-PtH would be a more viable option.

General performance evaluation method of integrated solar combined cycle (ISCC) system

As a novel solar energy utilization method, integrated solar combined cycle (ISCC) system has the advantages of low investment and high efficiency, and has been paid more and more attention. How to evaluate the effectiveness of solar energy integration in different ISCC systems has become a significant issue. In this paper, based on the second law of thermodynamics and the principle of energy cascade utilization, according to different kinds of integration methods, different kinds of basic ISCC system models are divided and established; Compared with the gas turbine combined cycle (GTCC) system and solar energy generating system (SEGS), the effects caused by the integration of solar energy are revealed: the superimposed effect of the fuel saving factor and the efficiency enhancement of efficiency promotion factor are given. The comprehensive evaluation factor with simultaneous consideration of both the fuel saving factor and the efficiency promotion factor is put forward. Meanwhile, the applications of this evaluation factor in actual cases of this evaluation factor are also studied. This paper provides a novel evaluation method for comprehensively evaluate two different ISCC systems which will propose valuable guidance for further evaluation research of ISCC system.

Thermoeconomic cost analysis on operation strategies of gas turbine combined cycle under off-design conditions

In this paper, the thermoeconomic cost model of a typical gas turbine combined cycle (GTCC) system is established based on the structure theory of thermoeconomics. Because the operation strategy is the basis of the research on the design/off-design condition of GTCC unit. Therefore, the GTCC thermoeconomic performances with different strategies using the inlet guided valve (IGV) control are compared based on the GTCC cost model to analysis the influence of the main parameters on the unit thermoeconomic cost of each component. The variation rules of the thermoeconomic performances of the GTCC unit under design/off-design operating conditions influenced by the operating strategy and ambient temperature are revealed. The results show that the GTCC with the IGV T3-650-F operation strategy has the lowest thermoeconomic cost. Changing the operation strategy of gas turbine (GT) can reduce the generator (GEN) unit thermoeconomic cost. And higher GT inlet/outlet temperature is helpful to reduce the thermoeconomic cost of combined cycle under off-design conditions. The investment on the steam turbine (ST) and the irreversibility of the combustion chamber (CC) have the important influence on the thermoeconomic cost of GTCC system. Reducing the air compressor (AC) inlet air temperature can reduce the thermoeconomic cost of GTCC system.

Load-regulation characteristics of gas turbine combined cycle power system controlled with compressor inlet air heating

Enhancing the peak-regulation performance of gas turbine combined cycle power units is significant in renewable energy accommodation. To improve the peak-regulation efficiency of the power units, the performance of the retrofitted system with compressor inlet air heating under alternative load-regulation strategies was comprehensively investigated. Three strategies were adopted, including inlet guide vane (IGV) control with constant turbine inlet temperature, IGV control with constant turbine exhaust temperature, and fuel flow control (FFC) to perform a comparative analysis of the system performance using a physical model, which was validated using a mathematical model. Operating charts of the retrofitted system were obtained and the effects of the compressor inlet air temperature on the power load rate were further investigated. The analysis indicates that FFC is preferred for gas turbines owing to the lowest exhaust temperature, and IGV control strategies are advantageous to the combined cycle power system owing to the performance improvement of the bottoming cycle. When the compressor inlet air is heated from 15 to 35 °C at the specific gross output of 320 MW, the gas turbine load rate increases by 4.16 and 3.01% under IGV control with constant turbine exhaust temperature and FFC, respectively, and the relative combined cycle power efficiency increases by 0.015 and 0.023, respectively. For a load power of 360 MW at the ambient temperatures of 5, 15 and 25 °C, the optimum outlet air temperature of the recuperator decreases from 32.0, 31.6 to 28.8 °C, respectively for IGV control with constant turbine exhaust temperature.

Black liquor gasification with calcium looping for carbon-negative pulp and paper industry

Although considered one of the major energy-intensive industries (EIIs), the pulp and paper industry has also the potential for energy production from an industrial waste, black liquor. This study proposes black liquor gasification (BLG) coupled with calcium looping (CaL) as a CO2 capture route for the pulp and paper industry. BLG with H2 production (BLG-CaL-H2), BLG with gas turbine combined cycle (BLG-CaL-GT) or with solid oxide fuel cell (BLG-CaL-SOFC) were considered. The dependence of carbon capture and storage (CCS) cost on the natural gas, limestone, electricity imported and H2 sale prices aside the expenditures related with BLG-CaL were evaluated. The CCS route, based on CaL retrofitted to the pulp and paper plant, was found to have a lower cost of CO2 avoided (39.0 €/tCO2) when compared with BLG-CaL (48.8–57.1 €/tCO2). Between the BLG-CaL scenarios, BLG-CaL-H2 presented the lowest cost of CO2 avoided (48.8 €/tCO2) but the highest energy penalty. Based on the thermodynamic performance, it was shown that CaL retrofit and BLG-CaL-SOFC presented the best overall performance, turning the electricity importer reference plant into electricity exporter. The economic sensitivity showed that the capital requirement of BLG-CaL has a strong effect on the cost of CO2 avoided for all alternatives. The H2 production is also strongly affected by the H2 sale price while BLG-CaL-SOFC and BLG-CaL-GT are strongly dependent on natural gas price.

Opportunities for installed combined heat and power (CHP) to increase grid flexibility in the U.S.

Increasing use of renewable energy requires sufficient grid flexibility to address uncertainty and variability in electricity generation. Previous studies suggest that combined heat and power (CHP) systems may support grid flexibility but they do not consider operating hours. In this paper, we used CHP operating data and determined annual and monthly availability of the installed CHP capacity from various sectors (e.g., utility, independent power producer, commercial, and industrial) in all seven U.S. independent system operators (ISOs) and regional transmission organizations (RTOs). Also, we estimated hourly CHP availability installed in five facility types (i.e., hospitals, universities, hotels, offices, and manufacturing) in the state of New York. The results show that regardless of ISO/RTO, sector, or season, more than 40% of the installed CHP capacity (0.7–8.7 GW) was not fully utilized in 2019; the results are similar for 2018. This available CHP capacity accounted for up to 9% of the ISO/RTO's peak electric demand, which may yield cost savings up to $16 billion by avoiding installation costs of new natural gas combustion or combined-cycle turbines. To exploit the available CHP capacity to enhance grid flexibility, we recommend different policy implications including flexible contract lengths between CHP owners and grid operators, improved market designs, and simplified interconnection standards.

Comparative feasibility study of combined cycles for marine power system in a large container ship considering energy efficiency design index (EEDI)

This study investigates an appropriate combined cycle as the electric propulsion system in a large container ship. A gas turbine combined cycle and molten carbonate fuel cell-steam turbine cycle are considered; the gas turbine uses LNG or hythane fuels. Because it is difficult to choose an appropriate propulsion system from only one perspective, comprehensive and unbiased analyses refer to the system performance, eco-efficiency, and economic feasibility for three configurations. An LNG-fueled COGES (combined gas turbine and steam integrated electric drive system) seems to be a promising alternative with regards to economic feasibility as well as a greenhouse gas regulation. The following alternative is the molten carbonate fuel cell-steam turbine cycle. A hythane-fueled COGES has a relatively low economic feasibility but will be the sole propulsion system if the regulation of greenhouse gas emission from shipping is stringent. On the other hand, the carbon taxation and implementation of an incentive for hydrogen fuel may facilitate a greener shipping environment; the additional eco-friendly policy for the shipping industry needs to be provided, shortly soon.

აირტურბინული კომბინირებული ციკლის ენერგობლოკების განტვირთვის ახალი შესაძლებლობები

The determining factor for the efficient operation of electrical systems is their stability. To ensure stability, it is important to establish links between neighboring electrical systems, enhance the capacity of overloading and unloading power plants, improving the flexibility of power plants, etc. For electrical systems with high autonomy, it is also important to solve the problems of power control by the installations of the system itself, including the combined cycle power units, the main purpose of which is to cover the base load of the grid. The studies carried out by the authors of the article have shown that the tasks of regulating the load of electric power systems can be solved by using power units of a gas turbine combined cycle. In order to achieve this, it is required to identify and realize deep unloading capabilities of such power generating units. In standard conditions the combined cycle power generating units are utilized for covering base loads, and their participation in a daily regulation of the grid load is not considered. However, the concept of the combined power control method suggested by the authors of this article involves combination of quantitative and qualitative regulation methods of the gas turbine component which significantly expands the unloading range of such power generating units and increases their engagement in regulating the power system loads.

Multi-objective linear-regression-based optimization of a hybrid solar-gas turbine combined cycle with absorption inlet-air cooling unit

Gas turbine (GT) power plants suffer from sensitivity to ambient-air temperature, high fuel consumption, and a high amount of waste heat dumped into the ambient. Various solutions were proposed to solve these drawbacks, which could simultaneously solve at most two problems, usually, at the expense of the third. In this work, however, a novel integration consisting of cascaded solar heat exchangers and a combined cycle power plant CCPP was used to simultaneously address the GTs shortcomings. Parabolic trough collectors PTCs were used to initially preheat the air at the combustion chamber inlet. The collectors were then used to drive an absorption inlet-air cooling cycle that will control the air temperature at the compressor’s inlet. Simple design point analysis of the proposed integration showed an increase in thermal efficiency by 7.2% and a 27.7 MW increase in power output. A linear-regression LR based optimization was then performed to generate highly accurate polynomial equations for predicting the system’s performance. These equations were then used in a Genetic Algorithm GA multi-objective optimization MOO with efficiency and capital cost as conflicting objectives. The optimum thermal efficiency was found to be in the range of 53.1 – 61.11% corresponding to a capital cost of the novel system in the range of 86.5–158.3 Mil$. A favorable optimum point for both objectives was found at an efficiency of 57.86% corresponding to a capital cost of 131.8 Mil$. Feasibility in terms of the payback period (PBP) was explored for the optimum range; resulting in a PBP equal to 2.8 years, an implication of a feasible novel cycle.

Thermodynamic analysis of chemical precooled turbine combined engine cycle

The precooling technology is an effective way to expand the flight envelope of the turbine engine. To solve the problem of engine performance degradation caused by excessive fuel consumption, a new type of chemical precooled engine cycle is proposed, in which part of the heat energy from the incoming air is converted into the chemical energy by pyrolytic reaction. To evaluate the engine performance, a thermodynamic model is established. Based on this model, the experiments are performed to obtain the chemical heat sink of selected fuels. Through the simulation, it is found that the specific impulse is greatly improved because the fuel consumption is effectively reduced by introducing the chemical precooling process. Moreover, the highest operating Mach number (HOMN) of the precooled turbine channel is effected by different component parameters, among which the increase of the turbine inlet temperature has the most significant effect on rising the HOMN. Furthermore, the optimal fuel ratio can be obtained when the equivalence ratio is equal to 1.0, and the fuel consumption can be saved by 42% ~ 52% at this time. In general, the results in this paper are beneficial for developing high-performance turbine combined engines.

A Drainpipe Leakage Caused by Under-Deposit Corrosion in a Gas–Steam Turbine Combined Cycle Power Plant

A drainpipe of a gas–steam turbine combined cycle power plant leaked after served for only 64 months. The chemical compositions, metallographic structure and mechanical properties were qualified, and therefore, the leakage was not caused by material quality. The comprehensive analysis of leakage morphology and deposition revealed that the leakage was caused by under-deposit corrosion. The decarburization of metallographic structure was not detected, which indicated that H generated by cathodic reaction has not occurred, so that the under-deposit corrosion caused by H+ was ruled out. The deposition was the iron oxides. The substances (mainly Na3PO4) used for chemical cleaning absorbed in deposition resulted in occluded alkaline electrolyte and damaged the protective film of pipe wall, and electrochemical corrosion process caused the drainpipe failure subsequently. The process and mechanism of pipe wall thinning and leakage in the working medium without heating concentration and corrosion substances were revealed. The preventive suggestions were also proposed for such a failure.

Biomass integrated gasification-gas turbine combined cycle (BIG/GTCC) implementation in the Brazilian sugarcane industry: Economic and environmental appraisal

This study presents an economical and environmental appraisal of the Biomass Integrated Gasification/Gas Turbine Combined Cycle (BIG-GTCC) introduction in a Brazilian sugarcane mill to increase the mill power generation potential. The analysis considers the introduction of torrefaction technology as a pretreatment procedure for wet bagasse to settle the feeding problems experienced during the gasifier continuous operation using this powdered feedstock. The environmental impacts after integrating the BIG-GTCC technology were determined using the life cycle assessment. When analyzed for the behavior of expected annual revenue in both configurations, the implementation of gasification of the surplus volume of the plant bagasse appears as the best option from an economic and environmental viewpoint.

Effects of market and climatic conditions over a gas turbine combined cycle integrated with a Heat Pump for inlet cooling

The growing need of dispatchable units, capable to balance the variable renewable energy electrical production leads to the development of strategies aimed at increasing power plants operational flexibility and global efficiency in part-load operation. A highly efficient heat pump (integrated in a conventional natural gas combined cycle is here proposed as a flexibility enhancement solution. Such concept, applied to power oriented combined cycle, allows to modify the compressor intake temperature with a consequent increase of the power production. While this operation for open cycle gas turbine is beneficial also to electric efficiency, combined cycles’ efficiency is less sensitive to the temperature variation and thus more influenced by the auxiliary consumption. The selection of the proper heat pump size for the proposed layout was based on an optimization process considering both combined cycle and heat pump off-design performance. After a statistical analysis of climatic data and their correlations with energy market condition for the six Italian price zones, the models developed were applied to assess the thermoeconomic potential of the proposed layout. This work highlights how a proper optimization process influences both revenues and size optimization and to highlight how such integrated system can be selected at its best considering typical market and climatic frames. The ratio between the air-cooled heat pump electrical consumption and the electrical combined cycle capacity that maximize power production increase was found to be 1/100. This finding can be extended to the others world Humid subtropical climate and Mediterranean hot summer climates zones. It is underlined how electrical market conditions could jeopardize the installation profits even under favourable climatic potential reducing the optimal economic heat pump size. Using off-design curves and optimization algorithm in performing coupling analysis appears to be more effective, with respect to simplified calculations under unfavourable economic and climate conditions.

Simulation of Optimizing the Partial Load Performance of a Gas Turbine Combined Cycle Using Exhaust Heat Recuperation and Inlet Bleed Heating

Abstract This paper proposes a novel method to extend the operating range and improve the partial load efficiency of the gas turbine combined cycle (GTCC). The combination of exhaust heat recuperation and inlet bleed heating (IBH) was evaluated through a cycle simulation. The degree of heat recuperation was modulated during partial load operation to enhance the cycle efficiency. The recuperation ratio was modulated before control of the variable inlet guide vane (VIGV) began. This means that the recuperation control covers the high partial load regime. The gas turbine power remained almost constant in this regime because the inlet flow rate and turbine inlet temperature (TIT) were kept constant. In contrast, the power of the bottoming cycle decreased with increasing recuperation ratio due to the decrease in exhaust gas energy. After the recuperation ratio reached a limit, the load control was the same, as in conventional plants: VIGV control followed by fuel only control. The purpose of using IBH was to reduce CO emissions in the low load regime. Some of the compressor discharge air was recirculated to the compressor inlet, and the combustion temperature was maintained at a high level. Both IBH and recuperation were effective in extending the operating range. The turndown ratio was predicted to decrease by approximately 10%p. The efficiency remained higher than the full load efficiency over a wide partial load range. The efficiency of the recuperated GTCC was 4.1%p higher at 50% power than that of the conventional GTCC.