Triple-pressure Heat Recovery Steam Generator Research Articles

Comparison of four layouts of optimized triple-pressure heat recovery steam generator

Comparison of four layouts of optimized triple-pressure heat recovery steam generator

An investigation of optimal values in single and multi-criteria optimizations of a solar boosted innovative tri-generation energy system

In this research, a tri-generation combined cycle is presented. This proposed system is equipped with a triple-pressure heat recovery steam generator with a novel configuration of heat exchangers to exploit the maximum possible waste heat. The gas turbine cycle also utilizes Parabolic Trough Solar Collectors to reduce the fuel consumption and CO2 emission. The low-pressure steam of the heat recovery steam generator is used as the motive steam of a multi-effect desalination unit for freshwater production, and the heat rejection of the steam cycle is utilized in a double effect absorption chiller to generate a cooling load. According to these modifications, the HRSG exhaust has considerable energy after the low-pressure steam of the heat recovery steam generator; hence, an organic Rankine cycle with a zeotropic mixture as working fluid is used to recover the energy. The proposed model is implemented in MATLAB software, and the energy, exergy, economic and environmental analyses are conducted on the model. Five single- and multi-criteria optimizations are conducted to determine the proposed system's optimum operating condition from different aspects. The results are presented as 2D and 3D Pareto Frontiers. A comparative study on scatters of distribution is presented as a novel approach to investigate each optimization objective's effect on decision variables through single- or multi-objective optimization. Referring to analyses utilizing the solar collectors mitigate the fuel consumption from 6.31 kg/s to 6.01 kg/s and results in a decrease of 0.81 kg/s CO2 productions. Besides, the waste heat recovery in the heat recovery steam generator attained a 20.17% exergy efficiency increase as well as 181.82 m3/h freshwater production and 5.98 MW cooling load as the secondary outputs and rose the power production from 74.87 MW to 140.92 MW. The best point on the 3D Pareto Frontier of the tri-objective optimization obtained the exergy efficiency of 45.86%, the total cost rate of 1.161$/s, and the CO2 emission of 17.05 kg/s.

Energy, Exergy, Environmental (3E) and Parametric Assessment of a Triple-Pressure Reheat Combined-Cycle Power Plant

Abstract In this study, energy, exergy, and environmental (3E) assessments have been conducted on a proposed combined-cycle power plant (CCPP) with three pressure levels of the HRSG and reheating process. 3E design approaches cross-link mechano-electric and environmental objectives. Herewith, the suggested combined-cycle is formed by a gas unit, condenser, steam turbines, triple-pressure heat recovery steam generator (HRSG) and also utilizes reheat facilities and auxiliary components. It is observed that more than 56% of total exergy destruction occurs in the combustor, followed by HRSG (15.29%), steam turbines (roughly 15.02%), gas turbine (8.93%), air compressor (1.79%), and condenser (0.66%). A parametric study is also presented that examines the sensitivity of performance indicators to various environmental states, steam pressures, pinch points, and steam mass flow rates. Moreover, it is presented that the implementation of Siemens SGT-100-1S over other GT configurations can considerably reduce deficiency of the overall cycle. The effects of each contaminant mass flowrate (NOx, CO, UHC, and CO2) and adiabatic flame temperature (AFT) are also studied when the gas unit operates under partial power and incomplete combustion conditions. In conclusion, a number of potential causes of irreversibilities and corrective optimization guidance are offered for each main equipment of the CCPP.

Modelling, Sensitivity and Exergy Analysis of Triple-Pressure Heat Recovery Steam Generator

Combined with the increasing demand for environmental pollution and electrical energy, combined cycle power plant power plants are increasingly important. It is necessary to increase the performance of power plants, reduce carbon emissions and increase energy production. Any change to the heat recovery steam generator design is an important component of the combined cycle power plant, as it directly affects the performance of the combined cycle power plant. This study describes the modeling, sensitivity and exergy analysis of a HRSG in a combined cycle power plant. Three-pressure HRSG was modeled with the Aspen Plus simulation program and sensitivity analysis was performed. At the same time, energy and exergy analyzes were made for each component in the combined cycle power plant.

Using the Openmodelica Environment to Simulate Start-Ups of a Triple-Pressure Heat-Recovery Steam Generator

A dynamic model of a triple-pressure heat-recovery steam generator (HRSG) is developed. The basic equations of the model are described. Cold and hot start-ups of an HRSG are simulated. The simulation results are compared with archive data on start-ups of real equipment. Conclusions on future application of the simulation data are drawn.

Ability of adjusting heating/power for combined cooling heating and power system using alternative gas turbine operation strategies in combined cycle units

Gas turbine combined cycle (GTCC) based combined cooling, heating and power (CCHP) or combined heating and power (CHP) system driven by natural gas is encouraged to set up for district heating/cooling demand in China due to the clean and efficient energy conversion. This paper presents a GTCC based CCHP system, which consists of a heavy-duty gas turbine, triple-pressure heat recovery steam generator (HRSG), steam turbines, heat exchanger and absorption chiller. Turbine inlet temperature (TIT) strategy and inlet guide vanes (IGV) strategy for the gas turbine are adopted to access the part load performance. The energy distribution and exergy destruction of the CCHP system are investigated under different gas turbine loads. The primary energy saving rate (PESR) and carbon dioxide emission rate (CDER) are set up to evaluate the system at various gas turbine loads and steam extraction ratios. The ability of shaving peak power for the system is investigated. The results show that IGV plays a role in increasing the steam turbine power output and reducing the exhaust heat in HRSG but causes more exergy destruction in the steam turbine expansion process. The PESR and CDER have been enhanced as the steam extraction ratio increases for the same gas turbine load. The IGV strategy reinforces the part-load performance of the CCHP system. For instances, the PESR has been enhanced from 0.2409 to 0.3108, and CDER has been strengthened from 0.8274 to 0.8465 by the IGV strategy at half of gas turbine load and without steam extraction. For the same heating load, both PESR and CDER are enhanced by the IGV strategy. The ability of supplying heating is deteriorating as the decrease in TIT. The ability of shaving peaking power is going to be deteriorated as heating load increases. For the small heating load, like 50 MW, the advantage of the IGV strategy is prominent, the PESR and CDER is advanced 5.81% and 1.48% respectively by the IGV strategy.

The extension of the operational range of combined-cycle power plant with a triple-pressure heat recovery steam generator

In the article, the issues of operational flexibility improvement for CCGT with a triple-pressure heat recovery steam generator are described. The factors limiting the operational range of CCGT were identified and analyzed. Analytical dependences for the minimum and maximum load of the CCGT on the ambient air temperature were obtained. The ways of expanding an operational range due to water spray into air-intake path, supplementary firing before the heat recovery steam generator, intensifying regulation of compressor airflow using the IGV and its pre-heating are described.

Repowering Options for Complying with Canadian CO2 Emission Intensity Limits on Existing Coal Plants

The Canadian federal government has introduced carbon dioxide emission intensity limits of no greater than 420 kg/MWh net for new coal plants and existing coal plants more than 50 years of age. Many operating coal plants in Canada will be impacted by this legislation in the near future, requiring operators to plan a compliance strategy. The Canadian Clean Power Coalition (CCPC) investigated the performance and economics of a number of options for existing plants that could deliver compliant solutions. These options included strategies in which natural gas is available and some in which only coal firing is feasible due to cost or logistical issues.Repowering and post-combustion capture (PCC) options were studied using an eastern Canadian power plant firing bituminous coal. The base-case (BC) option was a new combined-cycle gas turbine (CCGT) plant, against which all other options were compared. The following cases were investigated:1.PCC using:a.Monoethanolamine MEA solvent with crossover steam regenerationb.Commercial advanced solvent with crossover steam regenerationc.Commercial advanced solvent with a small gas turbine (GT) and a low-pressure steam generatord.Commercial advanced solvent with a GT, triple-pressure heat recovery steam generator (HRSG) and a back pressure steam turbinee.Commercial advanced solvent with a natural gas boiler and a back pressure steam turbine2.Repowering of existing steam turbines with new a GT and HRSG3.Repowering of existing steam turbines with fuel cellsa.New solid oxide fuel cell (SOFC) topping unitb.New molten carbonate fuel cell (MCFC) topping unit4.Expanded PCC approach with:a.Third unit with full LP steam turbine bypass supplying steam to PCCb.Circulating fluidized bed (CFB) boiler and back pressure steam turbineOne of the issues with incorporating PCC in an existing facility is delivering the thermal regeneration energy to the PCC reboilers in an efficient and cost-effective manner. This can involve significant integration with the low-pressure stages of the steam turbine, a duty for which the turbine was not designed. Because turbine modifications (to deliver partially expanded steam to the PCC plant) can be costly and would require significant down time, alternative strategies were investigated in which the PCC facility would effectively be a “standalone” facility, with the main plant interfaces being the flue gas to be treated and some shared services.The costing analysis was carried out on the following basis: 30-year plant design life (with life-extension costs included for existing plant), 90% capacity factor for the first year cost of electricity (COE), and a coal cost of $4.73/GJ and a natural gas cost of $10.00/GJ (based on 2013 forecasted costs). Case 2 (repowering existing steam turbines with new natural gas combined-cycle plant) without any additional CO2 abatement, delivered both the lowest capital costs and cost of electricity. If the existing coal boiler plant remains operational, the lowest costs were achieved by installing a molten carbonate fuel cell (Case 3b) followed closely with an advanced solvent PCC unit with solvent regeneration thermal energy being delivered by an efficient, small, dedicated gas turbine with a triple pressure HRSG (Case 1d). Where there is no existing infrastructure to deliver natural gas, the traditional methodology of extracting crossover steam from the unit for PCC solvent regeneration proved to be the lowest-cost option.

HRSG Analysis Using Pinch Principle

Vitality interest for a nation like India is expanding continuously. On this date, 70% of energy requirement is fulfilled by thermal power plant in India. Energy requirement has been expanded around 10% in last 10 years. Hence, engineers and researchers are trying hard to improve performance of plant. Combined Cycle Power Plant (CCPP) is using waste heat from gas cycle to generate power in steam cycle. In CCPP, Heat Recovery Steam Generator (HRSG) is major focus of researchers due to scope of performance improvement. There are various methods for parametric optimization of HRSG like exergy analysis, thermo-economic approach etc. Pinch Methodology is used as mathematical modelling tool. Generally, Dual pressure CCPP is used for low power generation capacity below 300 MW and Triple pressure CCPP is for higher range above 350 MW. For present study, Dual pressure and Triple pressure HRSG analysis is done with available literature data. The analysis includes pinch analysis, area and cost analysis using different pinch magnitudes. This analysis will be helpful in selecting optimized range of different parameters for safer operation, high durability of components and higher power output etc. In this paper, analysis of already existing plant data is done. The data such as pressure and temperature of HRSG components, mass flow rates, gas turbine and steam turbine output etc. are utilized for analysis in this paper. The Pinch methodology is applied to the data to achieve optimum performance in terms of higher reliability of power plant, less pollution, well thermally designed equipments etc.

Dynamic simulation of a triple-pressure combined-cycle plant: Hot start-up and shutdown

The operation of combined-cycle power plants is increasingly determined by frequent start-ups and shutdowns for grid balancing. This study investigates the capability of a comprehensive process simulation model to predict the transient response of a triple-pressure heat recovery steam generator (HRSG) with reheater to the start-up and shutdown procedures of a heavy-duty gas turbine. The model is based on geometry data, system descriptions and heat transfer calculations established in the original HRSG design. The numerical solution approach and the practical development of a suitable model structure, including the required control circuits, are explained. Detailed simulation results are presented, using initial conditions that correspond to a previous overnight shutdown. Calculations are performed for a complete operating cycle of the plant, where the following main phases are distinguished: start-up procedure, load-following operation, design operation and shutdown procedure. The numerical model is validated with measurement data of the commercial power plant for each pressure stage, yielding good agreement. Deviation from the transient behaviour of the real plant is discussed with regard to modelling assumptions and incomplete information on components outside the HRSG system boundaries.

Thermodynamic and economic analysis of a gas turbine combined cycle plant with oxy-combustion

Abstract This paper presents a gas turbine combined cycle plant with oxy-combustion and carbon dioxide capture. A gas turbine part of the unit with the operating parameters is presented. The methodology and results of optimization by the means of a genetic algorithm for the steam parts in three variants of the plant are shown. The variants of the plant differ by the heat recovery steam generator (HRSG) construction: the singlepressure HRSG (1P), the double-pressure HRSG with reheating (2PR), and the triple-pressure HRSG with reheating (3PR). For obtained results in all variants an economic evaluation was performed. The break-even prices of electricity were determined and the sensitivity analysis to the most significant economic factors were performed.

Thermodynamics and thermo-economic analysis of simple combined cycle with inlet fogging

The present study deals with thermodynamic and thermo-economic analysis of simple combined cycle power plant (CCPP), incorporated with gas turbine (GT) blade cooling by means of bleeding of compressed air, and compressor inlet air cooling by means of fogging. This study has been carried out for five configurations, namely, simple gas turbine combined cycle using single pressure heat recovery steam generator (HRSG), that is, (SGTCC1P), simple gas turbine combined cycle using double pressure HRSG (SGTCC2P), simple gas turbine combined cycle using double pressure HRSG with reheat (SGTCC2PR), simple gas turbine combined cycle using triple pressure HRSG (SGTCC3P) and simple gas turbine combined cycle using triple pressure HRSG with reheat (SGTCC3PR), considering the hot day condition(HDC) at ambient temperature of 40°C and relative humidity of 50%. The thermodynamic analysis has shown that SGTCC3P configuration of simple CCPP incur lowest operating cost per kWh power generation as determined in Fig. 19. This is obvious as evident in the Figs. 5, 6 and 9 of the thermodynamic analysis which show that for a given operating range of GTIT and Cpr, SGTCC3P configuration provides highest specific work and efficiency among all configurations.

Exergy and Energy Analysis of Combined Cycle systems with Different Bottoming Cycle Configurations

SUMMARY The paper deals with thermodynamic analysis of cooled gas turbine-based gas-steam combined cycle with single, dual, or triple pressure bottoming cycle configuration. The cooled gas turbine analyzed here uses air as blade coolant. Component-wise non-dimensionalized exergy destruction of the bottoming cycle has been quantified with the objective to identify the major sources of exergy destruction. The mass of steam generated in different configurations of heat recovery steam generator (HRSG) depends upon the number of steam pressure drums, desired pressure level, and steam temperature. For the selected set of operating parameters, maximum steam has been observed to be generated in the case of triple pressure HRSG = 19 kg/kg and minimum in single pressure HRSG = 17.25 kg/kg. Plant-efficiency and plant-specific works are both highest for triple-pressure bottoming cycle combined cycle. Non-dimensionalized exergy destruction in HRSG is least at 0.9% for B3P, whereas 1.23% for B2P, and highest at 3.2% for B1P illustrating that process irreversibility is least in the case of B3P and highest in B1P. Copyright © 2012 John Wiley & Sons, Ltd.

Optimization of the triple-pressure combined cycle power plant

The aim of this work was to develop a new system for optimization of parameters for combined cycle power plants (CCGTs) with triple-pressure heat recovery steam generator (HRSG). Thermodynamic and thermoeconomic optimizations were carried out. The objective of the thermodynamic optimization is to enhance the efficiency of the CCGTs and to maximize the power production in the steam cycle (steam turbine gross power). Improvement of the efficiency of the CCGT plants is achieved through optimization of the operating parameters: temperature difference between the gas and steam (pinch point P.P.) and the steam pressure in the HRSG. The objective of the thermoeconomic optimization is to minimize the production costs per unit of the generated electricity. Defining the optimal P.P. was the first step in the optimization procedure. Then, through the developed optimization process, other optimal operating parameters (steam pressure and condenser pressure) were identified. The developed system was demonstrated for the case of a 282 MW CCGT power plant with a typical design for commercial combined cycle power plants. The optimized combined cycle was compared with the regular CCGT plant.

Combined Cycle Power Plant Performance Analyses Based on the Single-Pressure and Multipressure Heat Recovery Steam Generator

AbstractIn this study sensitivity analysis is performed for single, double-pressure, and triple-pressure heat recovery steam generators in a combined cycle power plant. Steam pressure, evaporator pinch point, and economizer approach temperature differences are taken as design parameters. Temperature-heat (T-Q) graphics of heat recovery steam generator (HRSG) designs and the effects of design parameters to the plant efficiency, net power production, and heat transfer areas are obtained. The calculated results are useful to compare single and multipressure HRSGs in a combined cycle power plant scheme. In single-pressure, double-pressure, and triple-pressure HRSG, net power increment is approximately 0.05, 0.28, and 0.29% at every 10-bar inlet pressure increment. The net power output of the cycle decreases with increasing evaporator pinch point temperature difference. For single-pressure HRSG, this decrement is approximately 0.54%, whereas for double-pressure and triple-pressure HRSG it is approximately 0.21...

Thermodynamic analysis of a new conception of supplementary firing in a combined cycle

Thermodynamic analysis of a new conception of supplementary firing in a combined cycle The paper analyzes a new concept of integration of combined cycle with the installation of supplementary firing. The whole system was enclosed by thermodynamic analysis, which consists of a gas-steam unit with triple-pressure heat recovery steam generator. The system uses a determined model of the gas turbine and the assumptions relating to the construction features of steam-water part were made. The proposed conception involves building of supplementary firing installation only on part of the exhaust stream leaving the gas turbine. In the proposed solution superheater was divided into two sections, one of which was located on the exhaust gases leaving the installation of supplementary firing. The paper presents the results of the analyses of which the main aim was to demonstrate the superiority of the new thermodynamic concept of the supplementary firing over the classical one. For this purpose a model of a system was built, in which it was possible to carry out simulations of the gradual transition from a classically understood supplementary firing to the supplementary firing completely modified. For building of a model the GateCycle™ software was used.

Thermodynamic evaluation of combined cycle plants

Abstract The application of the exergy concept for the thermodynamic evaluation of energy conversion systems and chemical plants is steadily growing. However the general application of this concept is complicated by the large variety of parameters that is used to present the results of such evaluations. Easily understandable diagrams that offer a quick overview of the main results of such an evaluation will be very helpful. Large power plants, as for example combined cycle plants, consist of a large number of apparatuses. The thermodynamic modeling of these plants requires the computation of the thermodynamic properties at inlets and outlets of all apparatuses. These results allow for the calculation of the exergy values at all considered points after defining an appropriate environment. Using these exergy values exergy losses and efficiencies of all considered apparatuses can be determined. However, additional parameters and methods for presenting losses are necessary to understand the origin of exergy losses and the options for further improvements. Exergy efficiencies of power cycles show the actual losses but do in general not clearly indicate the potential for improvement. The use of the so-called internal exergy efficiency of a power cycle will be helpful to understand this potential. Also value diagrams and exergy flow diagrams are very useful to understand the thermodynamic performance of complicated systems. In this paper the application of these tools is demonstrated for the evaluation of alternative designs of combined cycle plants. Three system designs are established for this purpose and modeled using the computer program Cycle-Tempo. The considered combined cycles use the same gas turbine but have different steam bottoming cycles. Differences do originate from the number of pressure levels at which steam is generated in the HRSG (Heat Recovery Steam Generator). The evaluation includes respectively a single pressure, double pressure and triple pressure HRSG. The steam pressures are optimized with regard to overall plant efficiency using a multi-parameter optimization procedure. The evaluation shows that the application of the internal exergy efficiency of a power cycle is in particular useful if the temperature of heat transfer from the cycle will be affected by the cycle performance, i.e. in the case of gas turbine cycles. The value diagrams show how the increasing number of pressure levels of steam generation will reduce the losses due to heat transfer in the HRSG but also the exergy loss due to the exhaust of flue gas to the stack. The exergy flow diagrams show that the main exergy losses of combined cycle plants occur in the combustion process. Possibilities to reduce these losses are limited. Serious improvement of the efficiencies of future combined cycle plants is conceivable by applying high temperature fuel cells.

The influence of economic parameters on the optimal values of the design variables of a combined cycle plant

This paper presents the analysis of the influence of fuel price variation on the optimal values of the design variables of the steam part of a combined cycle plant. The investigated system was a power plant with a triple-pressure heat recovery steam generator and extraction-condensation steam turbine. Fourteen design variables for the steam part were identified. The variables that were optimised were the pressure levels of the working medium in the steam part of the system, and characteristic differences of temperatures in the heat recovery steam generator. Thanks to the development of an optimising programme, based on the genetic algorithms theory, it was possible to find an optimal solution. The indices of economic efficiency, in the form of the break-even price of electricity, were chosen as the objective function in the optimisations. The results of economic optimisations were compared with the results of the optimisation, where the electric efficiency was the objective function. This paper includes an analysis of the sensitivity of the economic objective function to failures in the adherence of the optimal values of decision variables. This analysis allowed the selection of variables such that a failure results in the highest increase of the break-even price of electricity.