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Article

Research and Development of the Combined Cycle Power Plants Working on Supercritical Carbon Dioxide

1
Department of Innovative Technologies of High-Tech Industries, National Research University “Moscow Power Engineering Institute”, 111250 Moscow, Russia
2
Department of Thermal Power Plants, National Research University “Moscow Power Engineering Institute”, 111250 Moscow, Russia
*
Author to whom correspondence should be addressed.
Inventions 2022, 7(3), 76; https://doi.org/10.3390/inventions7030076
Submission received: 28 July 2022 / Revised: 28 August 2022 / Accepted: 30 August 2022 / Published: 2 September 2022
(This article belongs to the Special Issue Thermodynamic and Technical Analysis for Sustainability (Volume 2))

Abstract

:
Today, the use of combined cycle gas turbine (CCGT) plants allows the most efficient conversion of the chemical heat of fossil fuels for generating electric power. In turn, the combined cycle efficiency is largely dependent on the working flow temperature upstream of a gas turbine. Thus, the net electric efficiency of advanced foreign-made CCGT plants can exceed 63%, whereas the net efficiency of domestic combined-cycle power plants is still relatively low. A promising method to increase the heat performance of CCGT plants may be their conversion from a steam heat carrier to a carbon dioxide one. In this paper, we have presented the results of thermodynamic research of a promising combined plant with two carbon dioxide heat recovery circuits based on the GTE-160 gas turbine plant (GTP). We have determined the pressure values that are optimal in terms of the net efficiency upstream and downstream of Brayton cycle turbines using supercritical carbon dioxide with recompression (30 and 8.5 MPa) and base version (38 and 8.0 MPa). The percentage of recompression was 32%. Based on the results of mathematical simulation of heat circuits, we have found out that the use of the solutions suggested allows the increase of the power plant’s net efficiency by 2.4% (up to 51.6%).

1. Introduction

1.1. Promising Methods to Increase the CCGT Plant Efficiency

Natural gas is currently one of the most common types of fuels: it accounts for about 23.6% of the total structure of electricity generation [1]. The most efficient conversion of the chemical energy of natural gas into electrical power is carried out by CCGT plants, in which most components of the working flow are combustion products of the air-and-fuel mixture (Brayton cycle) and water steam (Rankine cycle). The net electric efficiency of advanced CCGT plants exceeds 63%.
High efficiency figures, in particular, are demonstrated by CCGT using SGT5-9000HL gas turbine plants from Siemens, with the working flow temperature upstream of such plants being about 1550 °C and an exhaust gas temperature of 670 °C. In Russia, GTE-160 gas turbine plants are widely used, but they feature a significantly lower initial temperature of the working flow, of about 1100 °C, and an exhaust gas temperature equal to 537 °C. The net efficiency of these GTPs in a free running mode reaches 34.4%, and when operated as part of the CCP-220T CCGT power plant, it reaches 50.4%.
The most obvious method to increase the CCGT efficiency is increasing the working flow temperature upstream of the gas turbine. However, for this method to be implemented, we need to develop high-temperature technology for electric power generation [2,3].
An alternative way to increase the CCGT plant efficiency (by 2–3%) consists of the useful application of low-potential heat sources [4,5,6]. In particular, it is possible to add the organic Rankine cycle to CCGT plants for a deeper utilization of the exhaust gas heat or for decreasing the cold source temperature [7,8,9]. However, most heat carriers in low-temperature cycles (first of all, freons) are characterized by lower availability and chemical compound stability, as well as higher toxicity as compared to water. Besides, adding one more cycle entails an increase in capital costs for the power facility. The combination of the above factors was the main reason for the lack of widespread use of this technology [10,11].

1.2. Replacing the Water Stream Circuit with Carbon Dioxide for CCGT Plants

A promising method to increase the heat efficiency and to reduce the cost of power plants is the use of carbon dioxide as the working flow that works at supercritical parameters, which allows implementation of the Brayton cycle with low costs for auxiliary needs at a moderate initial temperature and compact dimensions of the main power equipment [12,13,14]. Today, at least five variations of carbon dioxide cycles are known [15,16,17]. The reasons why researchers worldwide are interested in this technology are largely related to the advantages of carbon dioxide as compared to other heat carriers.
In particular, carbon dioxide heat carriers feature low values of critical temperature (30.98 °C) and pressure (7.38 MPa). The low critical temperature of carbon dioxide, being close to the ambient temperature, makes it possible to compress the working flow near the saturation line [18,19], which reduces the compressor workload and the temperature of heat removal from the cycle without condensation of the working flow. In addition, carbon dioxide has a relatively low aggressiveness as compared to water and shows its corrosive activity only in the presence of moisture in gas or a water film on the metal surface. The price of carbon dioxide gas is comparable to that of the water heat carrier.
Long-term thermodynamic studies of S-CO2 power facilities resulted in the development of the five cycles presented in Figure 1. The simplest S-CO2 cycle is a closed Brayton cycle with the heat utilization of the exhaust gases (Figure 1a). It contains a compressor (C), regenerator (RH), reactor (R), turbine (T), electricity generator (G), and pre-cooler (PC). The S-CO2 Brayton cycle with reheating is shown in Figure 1b. Here, the turbine consists of a high-pressure turbine (HPT), and a low-pressure turbine (LPT). The S-CO2 Brayton cycle with intermediate cooling is presented in Figure 1c. The introduction of intermediate cooling allows for an increase in the cycle efficiency due to a reduction in the compressor’s energy consumption. The S-CO2 Brayton cycle with partial cooling is presented in Figure 1d. It differs from the simplest S-CO2 Brayton cycle (Figure 1a) by application of a cooler (CR), pump (P), recompressing compressor (RC), high-temperature regenerator (HTR), and low-temperature regenerator (LTR). The use of partial cooling together with two sections of regenerators improves the regeneration system’s efficiency.
With the initial working flow temperature of 550 °C, the most effective is the Brayton cycle using supercritical CO2 with recompression. Its net efficiency is 47.3% [20]. However, it should be noted that all the cycles under consideration are characterized by a high initial temperature of heat supply, which will certainly have a negative impact on the efficiency of the waste heat boiler. In this connection, additional measures are required to reduce the temperature of gases released into the atmosphere.
Many scientific studies consider combined plants with several sequential carbon dioxide recovery cycles [20,21]. Thus, the paper [21] assesses the impact of the heat circuit in heat recovery cycles on the efficiency of a combined plant operating based on Siemens SCC5-4000F. The exhaust gas temperature of this GTP is about 580 °C. The above research has established that one of the most effective options is using circuits with the recompression Brayton cycle and the Brayton cycle with partial heating; in this case, the net efficiency of a combined plant reaches 57.9%. At the same time, this study does not include a full optimization of the basic thermodynamic parameters, whereas the analysis of initial temperatures is little relevant for the domestic power sector.
In this paper, we have presented the results of our thermodynamic research of a promising combined plant with two carbon dioxide heat recovery circuits followed by a description of the main operation parameters of a power plant for electricity generation.

1.3. Current State of Research on Carbon Dioxide Cycles

In the modern literature, one can find many modifications of the considered basic configurations of the Brayton supercritical carbon dioxide cycle, which allow for increasing the efficiency of the power unit and expanding the applicability range [22,23].
One of the most attractive directions is the usage of the Brayton cycle with liquefied natural gas (LNG). Advantages of this technology are described in the work [24]. In particular, the use of liquefied natural gas increases the attractiveness of energy resources for maritime transport, which is relevant for plants operating in coastal areas. In addition, the use of liquefied natural gas could be used as a cooling stream. Therefore, it is advisable to use the heat generated at low potential sources, which significantly increases the efficiency of the Brayton cycle. According to the presented research results, the cycle efficiency could be equal to 52% at an inlet gas temperature of 550 °C. At the same time, the main disadvantages of this scheme are the narrow application range (it can be used only near a regasification terminal) and the expensiveness of LNG technology (it is more than twice as expensive as pipeline natural gas).
Due to the low boiling point of carbon dioxide at atmospheric pressure, the use of trigeneration cycles (plants producing heat, power, and chilled water for air conditioning or refrigeration), is becoming relevant. Particularly, the article [25] states that the advantage of trigeneration cycles is the high efficiency of the power unit up to 78% (heat cold and power energy are considered to be of equal value in calculations). The main disadvantages of this design are high complexity, poor maneuverability, and high capital costs due to additional compressor technology and heat exchangers.
The use of a pump compression process is more effective than the use of a compressor. In work [26], the Brayton cycle with condensation of heat carrier using acetone to dissolve carbon dioxide is considered. After compression in the compressor, the carbon dioxide is cooled down and dissolved in acetone. The mixture is then compressed by a pump, the carbon dioxide is separated, heated in a regenerator, and heated in a heater. Then supercritical CO2 is expanded in the turbine and cooled in the regenerator. The cycle efficiency is 56% at the turbine inlet temperature of 1400 °C.
It is worth noting that the modifications considered earlier lead to an increase in capital costs and technological complexity of the power unit. Therefore, the use of these solutions will negatively affect the payback period, reliability, and maneuverability of the combined cycle unit. Thus, it was decided to use the simple supercritical CO2 Brayton cycle with recompression and the basic option, allowing efficient utilization of low-potential heat.

1.4. Approaches to Energy Cycle Optimisation

Determination of the power cycle optimum parameters requires the definition of the target function, the variables, and the way of optimization. The main target function for optimization is efficiency. The main variable parameters usually are pressures and temperatures. In turn, the optimization approaches can be divided into three main categories.
Firstly, there is the equation-oriented approach. In this approach, the optimization problem and the simulation problem are solved simultaneously since the model equations are included as constraints in the problem. Thus, there is no distinction between independent and dependent variables or between model equations and technical-economic constraints. As a rule, the resulting optimization problem is solved by means of gradient-based algorithms using quadratic programming. It is worth noting that due to the large number of variables the algorithm may return local minima or even an unallowable solution if the first iterative point is far from the real value [27].
A second way to optimize energy cycles is to apply a black-box approach. In this approach, the optimization algorithm examines the space of independent design, and, for each sample solution, the simulation program develops a cycle diagram, outputting the power unit performance. The main advantage of the black-box approach is the higher probability of determining the global optimum, as the optimization only considers the independent variables and specification constraints that are hidden in the computational model. Another advantage of this approach is the ability to introduce corrective design variables to resolve potential inconsistencies. However, the black-box method has the disadvantage of omitting modeling constraints and transition conditions that are not obvious from the specification [28].
A final, common, way to optimize thermal schemes is to use the infeasible path approach. This model consists of a set of black boxes in which some equations are “open” and are included in the algorithm as constraints. To speed up the convergence of the target function in closed loops, the “open” equations are disabled (e.g., in the so-called “recycling equations” related to the recirculation of material and energy flows, as in the case of a recuperator), provided the desired accuracy is achieved. Thus, the main advantage is saving the computing time required for each black-box evaluation. On the other hand, the intermediate solutions chosen by the optimization algorithm are generally inadmissible since they do not satisfy the open constraints and feasibility is only guaranteed when the optimization algorithm achieves convergence. Furthermore, in addition to the independent decision variables, additional auxiliary variables (called “gap variables”) need to be optimized, which increases the computation time of the optimization algorithm [29].
Due to the aforementioned advantages, such as simplicity and relative convergence accuracy, this research will use the black-box approach, which is widely used in energy cycle optimization [28]. On the other hand, due to the complex equations modeling the cycle components, the resulting performance figures returned by the solver may be noisy and unsmooth.

2. Materials and Methods

2.1. Research Object

The object of study in this paper is a combined power plant. The initial design was that of a traditional CCP-220T combined-cycle plant with a dual-circuit steam turbine cycle. As a promising design, we have considered a combined plant based on GTE-160 using carbon dioxide recovery Brayton cycles with recompression and base version (Figure 2).
The promising power plant works as follows. Exhaust gases of GTE-160 (consisting of compressor C1, combustion chamber CC and gas turbine T1), with a temperature of 537 °C and a flow rate of 509 kg/s, are supplied to a high-temperature HE1 superheater where heat is transferred to the recompression cycle working flow, which is to carbon dioxide. After that, carbon dioxide is sent to carbon dioxide turbine T2 where the useful work is performed when the gas expands to the exhaust pressure. Then, the recompression cycle working flow is sent to a high-temperature heat regenerator HTR where heat is transferred from exhaust gases of the carbon dioxide turbine to a mixed flow downstream of the main and recompression compressors. Further on, carbon dioxide gas is supplied to a low-temperature regenerator LTR where exhaust gases, which have been previously cooled in HTR, transfer their residual heat to the flow downstream of the main compressor MC. Next, the working flow is separated: its main part is sent to the precooler PC, where the flow is cooled by circulation water (water is pumped by a circulation pump CP), and then, to the main compressor for compressing to the required pressure, whereas the other part of the flow with a higher temperature is sent directly to the recompression compressor RC. The first flow passes through low-temperature heat exchanges and is mixed with the recompression flow; after that, the full flow of CO2 is sent to the high-temperature heat exchanger and, further on, to the high-temperature superheater 1.
Next, the exhaust gas heat is recovered in a cycle with the base set, and the heat is transferred to the carbon dioxide gas in the high-temperature HE2 superheater. The heated CO2 is sent to the T3 carbon dioxide turbine, where the expanding working flow performs useful work. After that, the carbon dioxide gas is sent to the heat exchanger and, further on, to the precooler PC. The cooled carbon dioxide gas is sent to the C2 compressor for compression to the required pressure, after which the working flow is sent to the heat exchanger for utilization of the exhaust gas heat of the T3 carbon dioxide turbine [30].
The power equipment characteristics and invariable parameters in heat circuit plants, as used to calculate design options, are shown in Table 1.

2.2. Modeling Method

Aspen Plus was used for the computer simulation of the power production facilities. The working fluid thermophysical parameters were taken from the NIST Reference Fluid Thermodynamic and Transport Properties Database (REFPROP), a high-accuracy database [6]. The method for calculating thermodynamic processes is briefly explained below [21].
We have developed mathematical simulations for the recompression cycle and the cycle with base set. The exhaust gas parameters of the CCGT plant have been taken from open sources. An example of the mathematical simulation of a combined plant for electricity generation with a combined gas cycle and two carbon dioxide cycles is shown in Figure 3.
Heat exchangers have been calculated using heat and material balance equations. High-temperature and low-temperature heat exchangers in heat circuits have been simulated, taking into account the minimum temperature difference equal to 5 °C in high-temperature heaters, where the GT exhaust gas heat is recovered. The minimum temperature difference was assumed equal to 20 °C.
A parametric optimization of the carbon dioxide recovery cycles was carried out in a sequential direct search method. First, we varied the turbine exhaust gas pressure between 7 and 9.5 MPa. In the next step, we studied the effect on cycle performance of the degree of recompression ratio in the range 0 to 55%, as well as the values of turbine inlet pressure in the range 18 to 30 MPa. The net cycle efficiency was used as the optimization criterion. The mathematical model is a black-box.
The enthalpy at the end of the working flow expansion process in the turbine has been calculated using the following formula:
h o u t l e t . C O 2 T = h i n l e t . C O 2 T h i n l e t . C O 2 T     h o u t l e t . i s . C O 2 T · η C O 2 T ,
where h o u t l e t . C O 2 T —working fluid enthalpy at the turbine outlet, kJ/kg;
h i n l e t . C O 2 T —working fluid enthalpy at the turbine inlet, kJ/kg;
h o u t l e t . i s . C O 2 T —working fluid enthalpy at the turbine outlet at isentropic expansion, kJ/kg;
η C O 2 T —turbine isentropic efficiency, %.
The enthalpy at the end of the process of compression of the working fluid in the compressor was calculated using the following formula:
    h o u t l e t . C = h inlet . C + h outlet . is . C h inlet . C / η C ,
where h o u t l e t . C —working fluid enthalpy at the compressor outlet, kJ/kg;
h inlet . C —working fluid enthalpy at the compressor inlet, kJ/kg;
h outlet . is . C —working fluid enthalpy at the compressor outlet at isentropic expansion, kJ/kg;
η C —compressor isentropic efficiency, %.
Heat exchangers have been calculated using heat and material balance equations. High-temperature and low-temperature heat exchangers in heat circuits have been simulated, taking into account the minimum temperature difference equal to 5 °C in high-temperature heaters, where the GT exhaust gas heat is recovered, the minimum temperature difference being taken as equal to 20 °C.

2.3. Validation of the Modelling

Calculations for the gas turbine power plant as well as for the Brayton cycle with recompression are performed by the same iterative process. In this work, we have compared the energy performance of the recompression cycle with the literature data presented in [31]. Table 2 contains the main modeling results comparison.
Table 2 shows that the maximum calculation error of the mathematical model is 0.78%. This deviation is mostly due to the use of different databases of thermodynamic properties of carbon dioxide.

3. Results and Discussion

3.1. Optimisation of the CO2 Brayton Cycle with Recompression

The influence of turbine outlet pressure on the thermal efficiency of heat recovery cycles was estimated (Figure 4). Analysis of optimization results showed that the optimal final pressure at the turbine outlet in terms of useful efficiency for the Brayton cycle with recompression is 8.5 MPa (43.41%). Deviation from the above-mentioned values of pressure behind the turbine by 0.5 MPa will lead to a decrease in cycle efficiency, on average by 1.10%.
The nature of the resulting dependencies is due to the various intensity of changing the cost for compressing the working flow and the useful power generated by the turbine (Figure 5).
Optimization of Brayton’s cycle with recompression showed that the maximum value of cycle productivity can be achieved with inlet pressure equal to 24 MPa and at a recompression ratio equal to 37.5%: the cycle net efficiency reaches 43.7%. Thus, a deviation from optimum values for 1 MPa is accompanied by a mean 1.16% decrease in useful cycle efficiency, and a deviation of recompression fraction from optimum values for 5% is accompanied by a 0.90% decrease in net efficiency.
The main results of the optimization are shown in Figure 6. Decreasing the cycle efficiency with an increase in the recompression ratio is due to the rise in the total power used for the compressor drive.
Figure 7 shows a chart of electric power consumed by the main equipment.
The maximum power increase in the cycle is observed in the absence of recompression (Figure 8). This is due to the fact that in the absence of regeneration, the temperature of carbon dioxide flow decreases, which increases the amount of heat supplied to the cycle, reducing the temperature at the outlet of the heat recovery exchanger and increasing the amount of generated electricity. The change in waste gas temperature at the heat exchanger outlet with an increase in the recompression ratio is shown in Figure 9.
Based on the graph obtained, we can conclude that it is best to use the Brayton cycle with zero recompression ratio in the combined cycle, which will allow the generation of 55 MW of electrical energy with a net efficiency of 38%. The flue gas energy from the second cycle is directed to the basic Brayton CO2 cycle, which can reach a maximum net efficiency of 25% [21].

3.2. Optimisation of the Basic Version of the CO2 Brayton Cycle

While modeling the basic version of the Brayton cycle, the input data is taken from the previous calculation step. When optimizing the second circuit of the combined cycle, the pressure was varied based on the gas temperature (Figure 9), which varies from 398 °C to 311 °C.
The optimization results showed that with a pressure increase from 18 MPa to 38 MPa, there was a net efficiency improvement from 14.48% to 21.95%, while the net power increased from 37.11 MW to 53.37 MW. These dependencies are illustrated in Figure 10.
When optimizing the carbon dioxide combined cycle, the net pressure dependence of the Brayton carbon dioxide cycle with an advanced regeneration system was obtained, as shown in Figure 11.
Therefore, the heat effectiveness of the promising combined plant, which includes GTE-160 gas turbine plant (34.4%), carbon dioxide Brayton cycles with recompression (37.91%), and with base version (21.98%) used for heat recovery from GTE-160 exhaust gas, is of 51.6% with the optimal parameters presented in Table 3, which is 1.2% higher than the net efficiency of PGU-220T.
An increase in energy efficiency by 2.4% is due to the fact that the electricity generated by carbon dioxide turbines is 87.7 MW, while in the combined cycle part of the PGU-220T, the electric power is 75.5 MW. This phenomenon can be explained by the high average integral temperature of heat supply to the Brayton cycle with recompression. With the same working medium temperature upstream of the turbine, the carbon dioxide temperature upstream of the high-temperature superheater of the recompression cycle is 343 °C, whereas in two-circuit CCPs, the water is supplied to the economizer after an atmospheric deaerator with a temperature of about 100 °C. An additional positive effect is that carbon dioxide remains in the supercritical region and does not change its state of aggregation when heated compared to water in a CCGT. This provides a more efficient use of waste gas heat in the waste heat boiler to heat the working flow. However, when switching to a combined energy system with carbon dioxide cycles, own needs also increase (by 41 times), which is associated with the power used to compress carbon dioxide, while the released power of the combined Brayton cycle turns out to be 6.23% higher than that of PGU-220T.

4. Conclusions

  • The thermal scheme and mathematical model for the gas turbine combined cycle working on CO2 have been developed. The optimal values of the key thermodynamic parameters have been identified for the case of gas turbine unit GTE-160. It has been established, that at a temperature of 517 °C, the efficiency of the carbon dioxide Brayton cycle with recompression could be equal to 43.41% and achieve inlet and outlet turbine pressures of 24.0 and 8.5 MPa, respectively, and at the recompression percentage of 37.5%.
  • The maximum net power generation of 55.1 MW is achieved with a zero-recompression ratio with a net efficiency of 37.98% at a pressure of 30 MPa. This happens due to the fact that the temperature of carbon dioxide at the inlet to the waste heat boiler decreases, therefore, the heat supply to the highly efficient cycle increases.
  • When optimizing the secondary circuit, it was found that during the operation of the main Brayton cycle, the highest efficiency of the combined cycle is observed at pressures at the inlet and outlet of the turbine equal to 32 MPa and 8 MPa, at which the efficiency reaches 19.6%.
  • Based on the mathematical simulation, it was found that replacing the conventional steam power plant, which operates in combination with GTE-160 gas turbine plant and uses carbon dioxide Brayton cycles, with recompression and base version provides a 1.2% increase in the net efficiency of the combined power plant. Such an increase in efficiency can be explained by a high average integral temperature of the heat supply in the Brayton cycle, the carbon dioxide temperature upstream of HE1 being about 311 °C, whereas, in the conventional design, this value is about 100 °C (the temperature downstream of the atmospheric deaerator).

Author Contributions

Conceptualization, N.R. and A.R.; methodology, V.K.; software, V.K.; validation, I.K.; formal analysis, O.Z.; investigation, V.K., I.K., and O.Z.; resources, I.K.; data curation, O.Z.; writing—original draft preparation, V.K.; writing—review and editing, N.R.; visualization, I.K.; supervision, A.R.; project administration, A.R.; funding acquisition, O.Z. All authors have read and agreed to the published version of the manuscript.

Funding

This study conducted by the Moscow Power Engineering Institute was financially supported by the Ministry of Science and Higher Education of the Russian Federation (project no. FSWF-2020-0020).

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

Not applicable.

Conflicts of Interest

The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.

References

  1. World Energy Balances—International Energy Agency. Available online: https://www.iea.org/data-and-statistics/data-product/world-energy-balances (accessed on 1 August 2022).
  2. Uvarov, A.; Antonova, A.; Vorobjev, A. The Analysis of Initial Parameters of Steam in the Combined-Cycle Plant with High Temperature Gas Turbine. MATEC Web Conf. 2015, 37, 01062. [Google Scholar] [CrossRef]
  3. Rogalev, A.; Komarov, I.; Kindra, V.; Osipov, S. Methods for Competitiveness Improvement of High-Temperature Steam Turbine Power Plants. Inventions 2022, 7, 44. [Google Scholar] [CrossRef]
  4. Vélez, F.; Segovia, J.J.; Martín, M.C.; Antolín, G.; Chejne, F.; Quijano, A. A technical, economical and market review of organic Rankine cycles for the conversion of low-grade heat for power generation. Renew. Sustain. Energy Rev. 2012, 16, 4175–4189. [Google Scholar]
  5. Rogalev, N.; Kindra, V.; Komarov, I.; Osipov, S.; Zlyvko, O.; Lvov, D. Comparative Analysis of Low-Grade Heat Utilization Methods for Thermal Power Plants with Back-Pressure Steam Turbines. Energies 2021, 14, 8519. [Google Scholar] [CrossRef]
  6. Rogalev, A.; Rogalev, N.; Kindra, V.; Zlyvko, O.; Vegera, A. A Study of Low-Potential Heat Utilization Methods for Oxy-Fuel Combustion Power Cycles. Energies 2021, 14, 3364. [Google Scholar] [CrossRef]
  7. Cao, Y.; Mihardjo, L.W.; Dahari, M.; Tlili, I. Waste heat from a biomass fueled gas turbine for power generation via an ORC or compressor inlet cooling via an absorption refrigeration cycle: A thermoeconomic comparison. Appl. Therm. Eng. 2021, 182, 116117. [Google Scholar] [CrossRef]
  8. Kindra, V.; Rogalev, N.; Osipov, S.; Zlyvko, O.; Naumov, V. Research and Development of Trinary Power Cycles. Inventions 2022, 7, 56. [Google Scholar] [CrossRef]
  9. Braimakis, K.; Karellas, S. Energetic Optimization of Regenerative Organic Rankine Cycle (ORC) Configurations. Energy Convers. Manag. 2018, 159, 353–370. [Google Scholar] [CrossRef]
  10. Sun, W.; Yue, X.; Wang, Y. Exergy Efficiency Analysis of ORC (Organic Rankine Cycle) and ORC-Based Combined Cycles Driven by Low-Temperature Waste Heat. Energy Convers. Manag. 2017, 135, 63–73. [Google Scholar] [CrossRef]
  11. Shi, L.; Shu, G.; Tian, H.; Deng, S. A Review of Modified Organic Rankine Cycles (ORCs) for Internal Combustion Engine Waste Heat Recovery (ICE-WHR). Renew. Sustain. Energy Rev. 2018, 92, 95–110. [Google Scholar] [CrossRef]
  12. Xu, J.; Liu, C.; Sun, E.; Xie, J.; Li, M.; Yang, Y.; Liu, J. Perspective of S−CO2 Power Cycles. Energy 2019, 186, 115831. [Google Scholar] [CrossRef]
  13. Song, J.; Li, X.; Ren, X.; Gu, C. Performance Analysis and Parametric Optimization of Supercritical Carbon Dioxide (S-CO2) Cycle with Bottoming Organic Rankine Cycle (ORC). Energy 2018, 143, 406–416. [Google Scholar] [CrossRef]
  14. Song, J.; Li, X.-S.; Ren, X.-D.; Gu, C.-W. Performance improvement of a preheating supercritical CO2 (S-CO2) cycle based system for engine waste heat recovery. Energy Convers. Manag. 2018, 161, 225–233. [Google Scholar] [CrossRef]
  15. Dostal, V.; Hejzlar, P.; Driscoll, M.J. Supercritical Carbon Dioxide Cycle for Next Generation Nuclear Reactors. Ph.D. Thesis, MIT Center for Advanced Nuclear Energy Systems (CANES), Cambridge, MA, USA, 2004. [Google Scholar]
  16. Angelino, G. Real Gas Effects in Carbon Dioxide Cycles. In Gas Turbine Conference and Products Show; American Society of Mechanical Engineers: Cleveland, OH, USA, 1969; p. V001T01A071. [Google Scholar]
  17. Reyes-Belmonte, M.A.; Sebastián, A.; Romero, M.; González-Aguilar, J. Optimization of a recompression supercritical carbon dioxide cycle for an innovative central receiver solar power plant. Energy 2016, 112, 17–27. [Google Scholar] [CrossRef]
  18. Rogalev, A.; Kindra, V.; Komarov, I.; Osipov, S.; Zlyvko, O. Structural and Parametric Optimization of S-CO2 Thermal Power Plants with a Pulverized Coal-Fired Boiler Operating in Russia. Energies 2021, 14, 7136. [Google Scholar] [CrossRef]
  19. Liu, Y.; Wang, Y.; Huang, D. Supercritical CO2 Brayton Cycle: A State-of-the-Art Review. Energy 2019, 189, 115900. [Google Scholar]
  20. Cheng, W.-L.; Huang, W.-X.; Nian, Y.-L. Global Parameter Optimization and Criterion Formula of Supercritical Carbon Dioxide Brayton Cycle with Recompression. Energy Convers. Manag. 2017, 150, 669–677. [Google Scholar] [CrossRef]
  21. Thanganadar, D.; Asfand, F.; Patchigolla, K. Thermal Performance and Economic Analysis of Supercritical Carbon Dioxide Cycles in Combined Cycle Power Plant. Appl. Energy 2019, 255, 113836. [Google Scholar] [CrossRef]
  22. Invernizzi, C.M.; Iora, P. The exploitation of the physical exergy of liquid natural gas by closed power thermodynamic cycles. An overview. Energy 2016, 105, 2–15. [Google Scholar] [CrossRef]
  23. Angelino, G.; Invernizzi, C.M. Carbon dioxide power cycles using liquid natural gas as heat sink. Appl. Therm. Eng. 2009, 29, 2935–2941. [Google Scholar] [CrossRef]
  24. Qiang, W.; Yanzhong, L.; Xi, C. Exergy analysis of liquefied natural gas cold energy recovering cycles. Int. J. Energy Res. 2005, 29, 65–78. [Google Scholar] [CrossRef]
  25. Bellos, E.; Tzivanidis, C. Parametric Analysis of a Polygeneration System with CO2 Working Fluid. Appl. Sci. 2021, 11, 3215. [Google Scholar] [CrossRef]
  26. Li, X.; Huang, H.; Zhao, W. A supercritical or transcritical Rankine cycle with ejector using low-grade heat. Energy Convers. Manag. 2014, 78, 551–558. [Google Scholar] [CrossRef]
  27. Walraven, D.; Laenen, B.; D’haeseleer, W. Optimum configuration of shell-and-tube heat exchangers for the use in low-temperature organic Rankine cycles. Energy Convers. Manag. 2014, 83, 177–187. [Google Scholar] [CrossRef]
  28. Martelli, A.; Martelli, E.; Pierobon, L. Thermodynamic and technoeconomic optimization of Organic Rankine Cycle systems. In Organic Rankine cycle (ORC) Power Systems; Woodhead Publishing: Cambridge, UK, 2017; pp. 173–249. [Google Scholar]
  29. Biegler, L.; Cuthrell, J. Improved infeasible path optimization for sequential modular simulators—II: The optimization algorithm. Comput. Chem. Eng. 1985, 9, 257–267. [Google Scholar] [CrossRef]
  30. Shcherbatov, I.; Agibalov, V.; Dolgsuhev, A.; Belov, M. Subsystem for building a digital twin of the main and auxiliary equipment of thermal scheme of thermal power plant. In Society 5.0: Human-Centered Society Challenges and Solutions; Springer: Cham, Swizterland, 2022; pp. 239–249. [Google Scholar]
  31. Sarkar, J.; Bhattacharyya, S. Optimization of recompression S-CO2 power cycle with reheating. Energy Convers. Manag. 2009, 50, 1939–1945. [Google Scholar] [CrossRef]
Figure 1. Supercritical CO2 Brayton cycles: (a) S-CO2 Brayton cycle with regeneration; (b) S-CO2 Brayton cycle with reheating; (c) S-CO2 Brayton cycle with intermediate cooling; (d) S-CO2 Brayton cycle with partial cooling; (e) S-CO2 Brayton cycle with recompression. C—compressor, RH—regenerator, R—reactor, T—turbine, G—electricity generator, PC—pre-cooler, HTP—high-pressure turbine, LPT—low-pressure turbine, CR—cooler, P—pump, RC—recompressing compressor, HTR—high-temperature regenerator, LTR—low-temperature regenerator, MC—main compressor, and IC—intermediate cooler.
Figure 1. Supercritical CO2 Brayton cycles: (a) S-CO2 Brayton cycle with regeneration; (b) S-CO2 Brayton cycle with reheating; (c) S-CO2 Brayton cycle with intermediate cooling; (d) S-CO2 Brayton cycle with partial cooling; (e) S-CO2 Brayton cycle with recompression. C—compressor, RH—regenerator, R—reactor, T—turbine, G—electricity generator, PC—pre-cooler, HTP—high-pressure turbine, LPT—low-pressure turbine, CR—cooler, P—pump, RC—recompressing compressor, HTR—high-temperature regenerator, LTR—low-temperature regenerator, MC—main compressor, and IC—intermediate cooler.
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Figure 2. Combined Recompression & base version S-CO2 Brayton cycle.
Figure 2. Combined Recompression & base version S-CO2 Brayton cycle.
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Figure 3. Combined Recompression and base set S-CO2 Brayton cycle in Aspen Plus.
Figure 3. Combined Recompression and base set S-CO2 Brayton cycle in Aspen Plus.
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Figure 4. Dependence of the cycle net efficiency on carbon dioxide turbine exhaust pressure.
Figure 4. Dependence of the cycle net efficiency on carbon dioxide turbine exhaust pressure.
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Figure 5. Dependence of the useful efficiency of the cycle on the power of the turbine and the power of auxiliary needs at the pressure at the change outlet of the carbon dioxide turbine in the cycle with the base set.
Figure 5. Dependence of the useful efficiency of the cycle on the power of the turbine and the power of auxiliary needs at the pressure at the change outlet of the carbon dioxide turbine in the cycle with the base set.
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Figure 6. The effect of inlet pressure and recompression ratio on the net efficiency.
Figure 6. The effect of inlet pressure and recompression ratio on the net efficiency.
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Figure 7. Technical performance comparison of recompression Brayton cycle.
Figure 7. Technical performance comparison of recompression Brayton cycle.
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Figure 8. Dependence of cycle power on recompression ratio and turbine inlet pressure.
Figure 8. Dependence of cycle power on recompression ratio and turbine inlet pressure.
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Figure 9. Dependence of exhaust gas temperature on recompression ratio and turbine inlet pressure.
Figure 9. Dependence of exhaust gas temperature on recompression ratio and turbine inlet pressure.
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Figure 10. Investigation of the influence of pressure changes at the inlet to a carbon dioxide turbine. (a) Net efficiency. (b) Net power.
Figure 10. Investigation of the influence of pressure changes at the inlet to a carbon dioxide turbine. (a) Net efficiency. (b) Net power.
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Figure 11. Dependence of the efficiency of the combined cycle on the pressure in the carbon dioxide turbine of the second cycle.
Figure 11. Dependence of the efficiency of the combined cycle on the pressure in the carbon dioxide turbine of the second cycle.
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Table 1. Main characteristics and parameters for the calculation of thermal schemes.
Table 1. Main characteristics and parameters for the calculation of thermal schemes.
ParameterValue
GT flue gas massflow, kg/s509
GT inlet temperature, °C1200
GT inlet pressure, MPa12
GT pressure ratio10.9
Heater the first cycle hot end temperature difference, °C20
Heater the second cycle hot end temperature difference, °C10
Regenerator temperature difference, °C10
Turbine outlet temperature (GTE-160), °C537
Exhaust gas mass flow (GTE-160), kg/s509
Electrical net efficiency (GTE-160), %34.4
The cycle minimal temperature, °C30
Cooler circulation water pressure, bar1.3
Turbine specific internal efficiency, %90
Compressor specific internal efficiency, %85
Mechanical efficiency, %99
Power generator efficiency, %99
Power motor efficiency, %99
Heat transportation efficiency, %99
Table 2. Validation of Brayton supercritical cycle with recompression.
Table 2. Validation of Brayton supercritical cycle with recompression.
Tmin, °CTmax, °CPmax, BarrcoptXoptηth, %
[31]
ηth, % (This Work)Delt
505502002.390.183736.7136.930.599
505503002.80.25438.9339.0210.234
325502002.640.333741.1841.50.777
325503003.860.354943.3243.170.346
Table 3. Main characteristics and parameters for the calculation of thermal schemes.
Table 3. Main characteristics and parameters for the calculation of thermal schemes.
Optimized CycleInitial Temperature, °CInitial Pressure, MPaShare of Recompression, %Final Pressure, MPaNet Efficiency, %
Recompression cycle5173008.537.91
Basic cycle version31132-8.021.98
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Rogalev, A.; Rogalev, N.; Kindra, V.; Komarov, I.; Zlyvko, O. Research and Development of the Combined Cycle Power Plants Working on Supercritical Carbon Dioxide. Inventions 2022, 7, 76. https://doi.org/10.3390/inventions7030076

AMA Style

Rogalev A, Rogalev N, Kindra V, Komarov I, Zlyvko O. Research and Development of the Combined Cycle Power Plants Working on Supercritical Carbon Dioxide. Inventions. 2022; 7(3):76. https://doi.org/10.3390/inventions7030076

Chicago/Turabian Style

Rogalev, Andrey, Nikolay Rogalev, Vladimir Kindra, Ivan Komarov, and Olga Zlyvko. 2022. "Research and Development of the Combined Cycle Power Plants Working on Supercritical Carbon Dioxide" Inventions 7, no. 3: 76. https://doi.org/10.3390/inventions7030076

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