Pressure Heat Recovery Steam Generator Research Articles

4E analysis of three different configurations of a combined cycle power plant integrated with a solar power tower system

In this research, Abadan Combined cycle power plant in Iran has been studied 4E (Energy, Exergy, Economic and Environmental), and in order to improve its performance, three different configurations are proposed in which this Combined cycle power plant combines with a solar power tower system. The hybrid power plant is investigated in three modes of using the solar tower system, first preheat inlet fuel to the Combustion chamber, second preheat the Combustion chamber inlet air and finally its use in dual pressure Heat recovery steam generator of the power plant. The hybrid system results demonstrate that the system in the first configuration has the energy and exergy efficiency of 42.56% and 39.42% and the lowest initial cost among the three configurations. This system also reduces emissions from the combined power plant by 8041 tonnes/year. Results of the second configuration show the highest energy efficiency and exergy efficiency of 51.38% and 41.75%, respectively. This system saves $11 million in annual fuel consumption and prevents 34563tonnes/year of emissions from entering the atmosphere. The system in the third configuration has the energy and exergy efficiency of 47.8% and 40.97%, respectively and the highest power generation of 370.4 MW, among the other configurations.

Thermodynamic study of different configurations of gas-steam combined cycles employing intercooling and different means of cooling in topping cycle

Various options for improving the performance of gas/steam combined cycle, the performance enhancement can be achieved by increasing the turbine inlet temperature and/or increasing the cycle pressure ratio along with intercooling for reducing compression work and reheating for increasing the expansion work. The present paper analyses eight novel configurations of the intercooled gas turbine based combined cycles having the gas turbine blade cooled using closed loop cooling scheme. Combined cycle configurations differ in respect to cooling medium being steam or ammonia-water, intercooling, reheating, single/dual/triple pressure heat recovery steam generator, steam turbine, and ammonia water turbine. The comparative evaluation of combined cycle arrangements is based on thermodynamic modeling using first law and the second law of thermodynamics for the inlet temperature to turbine of 2000 K and ambient temperature of 303 K. Study aims at furnishing results for understanding the implications of modifications on the cycle performance. The results show that maximum 1142 kJ/kg of work is obtained for ammonia concentration of 0.6 while the maximum cycle efficiency of 53.87% and second law efficiency of 58.46% is obtained for ammonia concentration of 0.7 at cycle pressure ratio of 40 for combined cycle with triple pressure heat recovery vapor generator having ammonia-water cycle at high pressure& intermediate pressure and Rankine cycle at low pressure.

Performance Evaluation of a Combined Heat and Power Plant in the Niger Delta of Nigeria

This research presents the performance assessment of a combined heat and power plant operating in the Niger Delta region of Nigeria. The main focus is to evaluate the performance parameters of the gas turbine unit and the waste heat recovery generator section of the combined-heat-and-power plant. Data were gathered from the manufacturer’s manual, field and panel operator’s log sheets and the human machine interface (HMI) monitoring screen. The standard thermodynamic equations were used to determine the appropriate parameters of the various components of the gas turbine power plant as well as that of the heat exchangers of the heat recovery steam generator (HRSG). The outcome of all analysis indicated that for every 10C rise in ambient temperature of the compressor air intake there is an average of 0.146MW drop in the gas turbine power output, a fall of about 0.176% in the thermal efficiency of the plant, a decrease of about 2.46% in the combined-cycle thermal efficiency and an increase of about 0.0323 Kg/Kwh in specific fuel consumption of the plant. In evaluating the performance of the Waste Heat Boiler (WHB), the principle of heat balance above pinch was applied to a single steam pressure HRSG exhaust gas/steam temperature profile versus exhaust heat flow. Hence, the evaporative capacity (steam flow) of the HRSG was computed from the total heat transfer in the super-heaters and evaporator tubes using heat balance above pinch. The analysis revealed that the equivalent evaporation, evaporative capacity (steam flow) and the HRSG thermal efficiency depends on the heat exchanger’s heat load and its effective maintenance.

Performance Evaluation of a Combined Heat and Power Plant in the Niger Delta of Nigeria

This research presents the performance assessment of a combined heat and power plant operating in the Niger Delta region of Nigeria. The main focus is to evaluate the performance parameters of the gas turbine unit and the waste heat recovery generator section of the combined-heat-and-power plant. Data were gathered from the manufacturer’s manual, field and panel operator’s log sheets and the human machine interface (HMI) monitoring screen. The standard thermodynamic equations were used to determine the appropriate parameters of the various components of the gas turbine power plant as well as that of the heat exchangers of the heat recovery steam generator (HRSG). The outcome of all analysis indicated that for every 10C rise in ambient temperature of the compressor air intake there is an average of 0.146MW drop in the gas turbine power output, a fall of about 0.176% in the thermal efficiency of the plant, a decrease of about 2.46% in the combined-cycle thermal efficiency and an increase of about 0.0323 Kg/Kwh in specific fuel consumption of the plant. In evaluating the performance of the Waste Heat Boiler (WHB), the principle of heat balance above pinch was applied to a single steam pressure HRSG exhaust gas/steam temperature profile versus exhaust heat flow. Hence, the evaporative capacity (steam flow) of the HRSG was computed from the total heat transfer in the super-heaters and evaporator tubes using heat balance above pinch. The analysis revealed that the equivalent evaporation, evaporative capacity (steam flow) and the HRSG thermal efficiency depends on the heat exchanger’s heat load and its effective maintenance.

Energy and exergy analysis of a 747-MW combined cycle power plant Guddu

ABSTRACT The paper presents a detailed study based on the energy and exergy analysis of a combined cycle power plant (CCPP) Guddu having triple pressure heat recovery steam generator (HRSG). The energy loss and the energy efficiency of each plant component with HRSG as a whole is calculated. The exergy destruction of these components and the sub-parts of the HRSG are also found out. All the three stages of the steam turbine are analysed individually. The combustion chamber is found to have the maximum share of exergy destruction while the condenser is having a maximum of energy loss. The total net power output, energy and exergy efficiency of the whole plant is calculated as 737.8 MW, 59.12% and 58.24%, respectively. The error in getting the designed power output of 747 MW is 3.16%. The thermal efficiency of the Brayton and Rankine cycle is 62.01% and 56.38%, respectively.

Thermodynamic Study of Multi Pressure HRSG in Gas/Steam Combined Cycle Power Plant

Combined cycle power plants have a combination of gas based topping cycle and steam based bottoming cycle through the use of Heat Recovery Steam Generator (HRSG). These HRSG may be either of single pressure (SP) or dual pressure (DP) or multiple pressure type. Here in this study thermodynamic analysis is carried out for optimal performance of HRSG using different types of HRSG layout for combined cycle efficiency improvement. Performance of single pressure HRSG and dual pressure HRSG, utilized in gas/steam combined cycle is analyzed and presented here. In comparison to single pressure, dual pressure HRSG offers 10 to 15% higher reduction in stack temperature due to greater heat recovery and thus improved plant efficiency.

System effectiveness analysis of combined cycle cogeneration plant

Methodology for thermodynamic analysis, fuel efficiency determination, and mathematical economic calculation model of comparative economic effectiveness of combined-cycle cogeneration plant (CCCP) are elaborated. CCCP with a single, dual and triple pressure heat-recovery steam generators (HRSG) are investigated with account for real-time use in Heating System. Employment of CCCP with a triple pressure HRSG ensure high value of system effectiveness. Modes of CCCP, conditional and functional scope of electricity and heat, and condition of construction investment financing of CCCP are main factors have an impact on effectiveness of different schemes of CCCP.

Analysis of alternative configurations of heat recovery process in small and medium scale combined cycle power plants

In the paper various configurations of the heat recovery process in combined gas and steam cycle power plants of complex structures are examined. Proposed modifications concern mainly hot side temperature profile. It has been assumed that two gas turbines will be installed in the system with a common single pressure heat recovery steam generator. Exhaust gas from the boiler is introduced into the low-temperature Rankine cycle with an organic working fluid. Two configurations of heat exchangers have been proposed, that can be considered as an alternative solution to the conventional structures currently in use. Energy and exergy efficiency values have been calculated for different parameters of steam. In addition, the temperature of exhaust gas from gas turbines was assumed to be different, which corresponds to the use of turbines of different efficiency classes. It has been shown that, with appropriately high steam parameters and appropriately selected gas turbines, the proposed alternatives lead to an improvement of the system performance.

Performance improvement of distributed combined cycle plants through modification of structure

In this paper possible modifications of combined cycle power plants of electric power output below 50 MW are presented. The concept is based on modified configuration of a single pressure heat recovery steam generator and bigger number of system components. Alternative plant structures are examined theoretically using fundamental thermodynamic relations. Simulations were performed using the Engineering Equation Solver software package. Results show that there is a room for both efficiency and flexibility improvements. In the simulated cases the energy conversion efficiency of a combined cycle power plant increased from 49.9% up to 52.7%. In addition to this, design parameters such as gas turbine pressure ratio, combustion temperature, steam pressure are relatively low, in the range of values currently widely used in industry. The concept also assumes a bigger role of the ORC technology. Its share in the total power output increased from 5.5% in the reference case up to 12.6% in the configuration that achieves the highest value of energy efficiency.

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.

Thermodynamic investigation of parameters affecting the execution of steam injected cooled gas turbine based combined cycle power plant with vapor absorption inlet air cooling

Present paper deals with the thermodynamic investigation of influence of different parameters in steam injected cooled gas turbine based combined cycle power plant employing vapor absorption cooling of inlet air and two pressure heat recovery steam generator. Vapor absorption cooling scheme is run by utilizing the heat energy of the exhaust gas at the exit of HRSG. Gas turbine blades are cooled using film cooling technique. A study of the influence of ambient conditions, cycle pressure ratio, and turbine entry temperature on plant performance has been carried out. It has been noted that the efficiency of gas turbine improves by up to 6.91% and specific work output enhances by 16.42% with the integration of vapor absorption inlet air cooling to the simple cycle. The CCPP specific work output advances 17.34% at given turbine entry temperature as the steam to air ratio increases from 3% to 7% at the cycle pressure ratio of 24. Similarly thermal efficiency of CCPP increases by 6.78% for same cycle pressure ratio of 24 and the constant increment in steam to air ratio from 3 to 7%.

Constructal design and optimization of a dual pressure heat recovery steam generator

Optimum design of the Heat Recovery Steam Generator (HRSG) has noticeable effects on the thermal efficiency of the combined cycle power plants. In this paper, constructal design of a dual pressure HRSG is proposed. It is shown how to simultaneously optimize the operating and geometric design parameters of the HRSG by using the constructal theory. Considering the minimum total entropy generation as objective function, optimum parameters of the HRSG unit are derived by using the genetic algorithm method under the fixed total volume condition. The optimized total volume, aspect ratios of the units, the number of tubes through the length and width, the heat transfer area of the HRSG and thermodynamic properties are significant features of the flow configuration resulted from constructal design. Optimal aspect ratios of the units are correlated to the pressure and temperature and effects of these variables on the main geometric characteristics of HRSG are obtained. The results show that there is an optimum value for total volume of the HRSG and most of the overall heat transfer coefficient (UA) are allocated to the evaporators. Also, number of the tubes in the longitudinal direction are fewer than the number of tubes in the transverse direction.

The optimal design and 4E analysis of double pressure HRSG utilizing steam injection for Damavand power plant

Energy, Exergy, Exergoeconomic and Environmental (4E) analysis of combined cycle power plant utilizing the method of steam injection into the combustion chamber is performed in the current study. Steam is supplied from low pressure (LP) side of the heat recovery steam generator (HRSG). According to genetic algorithm's results, the steam injection elevates the total combined cycle power by 2 MW while lowers the design costs considerably at optimum state. Some parameters restrict the steam injection usage within combined cycles that could be noted as Gas turbine power decline; Gas turbine loss increase due to pressure loss; HRSG's manufacturing costs growth; opposition between high and low pressure flow rate variations; NOX and CO emission costs dependency on optimum conditions. This paper discusses the above limitations for implementation of such technology in combined cycles. At the optimum point, Exergy and thermal efficiencies values increased from 42% and 47.6% to 47.28% and 48.94% respectively. Optimum pinch and approach temperatures for HP and LP sides were computed to be 35, 20, 17 and 37.5, respectively. Also, the optimum value of X parameter is 23.28%; X is defined as the ratio of steam to the inlet air flow rate divided by the other fraction which is the ratio of fuel to input air flow rate while there is no steam injection into the combustion chamber.

Exergy analysis of the dual pressure HRSG for varying physical parameters

Heat recovery steam generator (HRSG) is used to capture the heat of gas turbine exhaust gases for generating steam to run the steam turbine in gas/steam combined cycle power plant (CCPP). The performance of HRSG affects the steam turbine output and thus the overall combined cycle performance. The present study considers operating conditions of a 663MW, combined cycle power plant at Auraiya (U.P.), India for carrying out the exergy based investigation of a dual pressure HRSG. Different physical parameters of HRSG such as fin height, fin density and fin thickness are varied for analyzing exergy loss and exergy efficiency at different steam generation pressures. The exergy analysis shows how the exergy losses get lowered for LP evaporator and the exergy efficiency improves in LP economizer for higher fin heights and fin densities.

Exergoeconomic analysis of a chemical looping reforming plant for hydrogen production

Chemical looping reforming (CLR) is an innovative way of producing hydrogen (H2) from fossil fuels with inherent carbon dioxide (CO2) capture capability. An exergoeconomic analysis has been performed on the plant consisting of a CLR system, a steam cycle which incorporates triple pressure heat recovery steam generator (HRSG), and H2 and CO2 compression systems. This study employs an Aspen plus model to obtain the thermodynamic data required from exergetic and exergoeconomic analyses. The results show that the system efficiencies are highly dependent on the reactor temperatures which, consequently, influence the plant outputs. The results from exergoeconomic analysis show that the specific costs for H2 and net power are 2.9 $/GJ and 26.7 $/GJ, respectively. HRSG and CLR units are the most important components. The cost rate of capital investment and the cost rate associated with the exergy destruction are the dominant factors for HRSG and CLR units, respectively.

Performance assessment and multi-objective optimization of an integrated organic Rankine cycle and multi-effect desalination system

Integrated energy systems have attracted ample attention due to the fact that they increase the efficiency of the system and consequently reduce the environmental impacts. Among integrated energy systems, integration of a gas turbine (GT) with a multi-effect desalination (MED) and an organic Rankine cycle (ORC) has introduced itself as a potential option. In this paper, a comprehensive thermodynamic modeling of an integrated system consisting of a micro gas turbine, a single pressure heat recovery steam generator (HRSG), an ORC and an MED is conducted. Exergy and economic analyses are performed. In addition, a multi-objective optimization is performed to determine optimized design parameters. Moreover, an optimization is performed for different working fluids including R123, R134a and R245fa. The distilled water production and the total cost rate (power generation price) are considered as two objective functions. The fast and elitist Non-dominated Sorting Genetic Algorithm II (NSGA-II) is applied to optimize the objective functions simultaneously. The results show that MED evaporator approach temperature has a significant effect on the optimum selected power and distilled water capacity. Furthermore, by increasing compressor pressure ratio, the exergy efficiency increases and the cost rate decreases. Moreover, R134a shows the best exergy efficiency compared with other fluids.

A discrete and continuous mathematical model for the optimal synthesis and design of dual pressure heat recovery steam generators coupled to two steam turbines

This paper addresses the optimal arrangement and design of a dual pressure heat recovery steam generator coupled to two steam turbines. A superstructure that embeds various alternative configurations is optimized considering the following two single objective functions: (a) the maximization of the total net power generation for a given total heat transfer area and (b) the minimization of the total heat transfer area for a given total net power. The optimal number of heat exchangers and pumps and how they should be connected are the discrete decisions. The dimensions and operating conditions are the continuous decisions. A discrete and continuous mathematical model is developed and logical propositions are used for discrete decisions. The results are compared with a reference case reported by other authors. The results indicated that the optimization of the proposed superstructure allowed to find a more efficient HRSG configuration. The obtained configurations differ from the configuration of the reference case in how the heat exchangers and pumps are connected. A considerable increase in about 8% of the total net power generation in (a) and a significant reduction in about 24% of the total heat transfer area in (b) are achieved when compared to the reference case.

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.

Exergy analysis of dual pressure HRSG for different dead states and varying steam generation states in gas/steam combined cycle power plant

This paper deals with exergy analysis of a dual pressure (DP) heat recovery steam generator (HRSG) having steam generation at high pressure (HP) and low pressure (LP) in the range of 50–70 bar and 2–6 bar respectively in the gas/steam combined cycle power plant for varying dead states. The in-operation plant data for this study are taken from a gas/steam combined cycle power plant at Auraiya (U.P.), India. Results have been obtained for exergy loss and exergy efficiency with varying dead state temperatures for different HP and LP steam generation states in different sections of HRSG. The exergy analysis for chosen conditions/parameters helps in locating the particular sections of the HRSG having maximum exergy loss. It is found that at varying steam generation pressures the HP and LP super heater sections and at higher dead state temperatures the HP evaporator are found to act as major source of irreversibilities. The results obtained are useful in finding the thermodynamic states that will help in reducing the exergy destruction for enhancing HRSG performance which eventually improves the efficiency of combined cycle power plants.

Investigations for performance enhancement of dual pressure HRSG in gas/steam combined cycle power plants

ABSTRACTA heat recovery steam generator (HRSG) is the vital equipment in a gas/steam combined cycle power plant (CCPP) which plays an important role in enhancing the overall performance of the plant. An HRSG is designed on the basis of the size of the gas and steam turbines used in the power plant. Therefore, the HRSG directly affects the performance of the CCPP and its optimisation based on physical design can improve the plant performance. In the present study, the plant data of the CCPP of NTPC Ltd. at Auraiya (U.P.), India, has been considered for study. A segmented finned model has been chosen as it is the preferred arrangement [Ganapathy, V. 2003. Industrial Boiler and Heat Recovery Steam Generator Design, Application and Calculation. New York: Marcel Dekker Inc.] and thermodynamic investigations have been carried out upon a dual pressure HRSG in a gas/steam CCPP from the perspective of maximum heat recovery and minimum pressure loss. The performance investigations of varying physical parameters of a dual pressure HRSG with segmented fins are useful for CCPP designers and for all those who are engaged in the area of heat recovery.