Optimization Of Heat Recovery Steam Generator Research Articles

Modeling and optimization of finless and finned tube heat recovery steam generators for cogeneration plants

AbstractThis article aims to model and optimize the fire tube Heat Recovery Steam Generator (HRSG) used in a gas microturbine cogeneration of heat and power system. Here, six cases including a finless and finned tube (solid and serrated) HRSGs with the inline and staggered arrangements are optimized and compared using techno‐economic assessment. Optimization of HRSG was carried out by applying two objective functions of minimizing the total annual cost as well as maximizing the exergy efficiency. Nondominated Sorting Genetic Algorithm II is used to find out the optimal values of design variables. The TOPSIS decision‐making process is employed to choose the optimum point of the Pareto front. A 600 kW gas microturbine cogeneration plant is considered as a case study. The results revealed that the finless tube HRSG with an inline arrangement has the lower pinch and approach temperatures (3.5°C and 3.1°C, respectively), the higher steam mass flow rate (12.7%), the lower total annual cost (64 096$/year), and the higher exergy efficiency (60.6%). It is also found that using the staggered arrangement tube banks along with the solid fins in HRSG leads the total annual cost, the steam mass flow rate, and exergy efficiency increase up to 41.6%, 100%, and 12.6%, respectively. This means that the thermodynamic performance improvement will compensate the total annual cost increment. Furthermore, it is demonstrated that HRSG with solid fins and staggered arrangement with total annual costs of (90 810$/year), exergy efficiency of (73.2%), and steam mass flow rate of (4680 kg/h) has the best performance in comparison with other finned tube cases.

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 a 420 MW combined cycle power plant

Combined cycle power plants (CCPPs) have an important role in power generation. The objective of this paper is to evaluate irreversibility of each part of Neka CCPP using the exergy analysis. The results show that the combustion chamber, gas turbine, duct burner and heat recovery steam generator (HRSG) are the main sources of irreversibility representing more than 83% of the overall exergy losses. The results show that the greatest exergy loss in the gas turbine occurs in the combustion chamber due to its high irreversibility. As the second major exergy loss is in HRSG, the optimization of HRSG has an important role in reducing the exergy loss of total combined cycle. In this case, LP-SH has the worst heat transfer process. The first law efficiency and the exergy efficiency of CCPP are calculated. Thermal and exergy efficiencies of Neka CCPP are 47 and 45.5% without duct burner, respectively. The results show that if the duct burner is added to HRSG, these efficiencies are reduced to 46 and 44%. Nevertheless, the results show that the CCPP output power increases by 7.38% when the duct burner is used. Copyright © 2007 John Wiley & Sons, Ltd.