Duct Burner Research Articles

Modeling combined-cycle power plants in a detailed electricity market model

The efficiency and flexibility of combined-cycle gas turbines (CCGT) are gaining importance in view of more decarbonized energy systems. Therefore, an adequate representation of CCGTs in large-scale energy system models is required. When modeling large-scale energy systems, a trade-off between detailed representation of the technical restrictions and reasonable computing times emerges because of limited computing capacities.We present an approach that accounts for the operational dependencies between the gas and steam turbines of a CCGT but remains applicable in large-scale market models. Duct burners and bypasses that enable the solo operation of steam or gas turbines are also modeled. We implement our approach using the well-established Joint Market Model and apply it in a case study of the German electricity system in 2040.Our modeling approach captures more detailed operation modes, while increases in computation time remain limited. Thus, the approach is advantageous when turbine-wise modeling and analysis of CCGTs is required, e.g. for a detailed analysis of start-ups and operations. The results show no substantial differences between the aggregated market results of five cases investigated. The consideration of bypasses and duct burners yet leads to higher contribution margins for individual CCGTs – with stronger effects observed for more efficient groups.

Converting Slovianska TPP with the central coal pulverizing plant from anthracite to sub-bituminous coal

Purpose. To develop scientific foundations and technical solutions and to implement the converting of the anthracite boiler of the 800 MW unit of Slovianska TPP with central coal pulverizing plant to sub-bituminous coal combustion with maximum use of existing equipment, without stopping the unit’s operation. Methodology. Theoretical and calculational studies on the processes of coal drying and pulverizing at the central coal pulverizing plant. Calculational justification of technical solutions to eliminate the risk of pulverized coal ignition in the pulverized coal supply system and in the boiler unit burners. Trial tests at the coal pulverizing plant and boiler unit. Findings. The technological features of coal pulverizing plant with steam panel dryers designed for anthracite and the peculiarities of the drying process of an individual coal particle were analyzed. It is substantiated that coal drying at the first stages takes place according to the “wet bulb thermometer” mechanism, and safe conditions for sub-bituminous coal pulverizing are determined and confirmed by tests. Technical solutions to eliminate the risk of pulverized coal ignition in the pulverized coal supply system and in the boiler burners were calculated and implemented, which allows the combustion of different coal grades (anthracite, sub-bituminous coal and their mixtures) without changing the composition of the air duct equipment and burners, using only operational measures. Originality. For the first time, it was proved that coal drying at the first stages takes place according to the “wet bulb thermometer” mechanism, and safe conditions for sub-bituminous coal pulverizing at the central pulverizing plant with steam panel dryers and unventilated ball drum mills were determined. Practical value. Technical solutions were developed and implemented to convert the anthracite boiler of the 800 MW unit of Slovianska TPP with a central coal pulverizing plant to sub-bituminous coal burning with maximal use of existing equipment, without stopping the unit’s operation, including safe modes of sub-bituminous coal pulverizing, as well as pulverized coal of various coal grades and their mixtures feeding and combustion. As a result of the implementation of the developed technical solutions, the 800 MW power unit of Slovianska TPP became the first unit in the world capable of using anthracite and sub-bituminous coal separately or in the form of mixtures of a wide range of compositions.

Numerical treatment of heat recovery steam generator harps constructed from multiple tube bundle configurations

The heat recovery steam generator (HRSG) can be regarded as a heat exchanger, which uses the heat rejected from the gas cycle to supply steam for the vapor cycle. HRSGs are consisted of many tube bundles (or harps). Supplying a duct burner in the upstream of an HRSG necessitates constructing the first bundle using different finned-tube materials with dissimilar fin configurations including unequal fin-pitch sizes. The computational fluid dynamics (CFD) has been widely used to study the flow through tube bundles; however, considering a fixed fin-pitch size for all rows of the finned-tubes. There is no trace of numerical analyses to treat tube bundles with unequal fin pitch sizes, apparently, because there are major challenges for the classical strategies, say unified-domain approach, to simulate tube bundles constructed from tubes with different fin configurations. This work introduces the splitted-domain approach as an innovative strategy to pass over the challenges with using the unified-domain approach. Then, these two approaches are used to model the superheater module of a real HRSG with available online measured data. The calculated Nusselt numbers and pressure drops indicate that the splitted-domain approach provides more accurate results than the unified one in simulating tube bundles constructed from tubes with dissimilar fin configurations.

Advanced Exergy-Based Audit of Heat Recovery Steam Generators: A Case Study

Abstract The current paper enhances the methods presented in The American Society of Mechanical Engineers (ASME) Performance Test Code (PTC) 4.1 and 4.4 and proposes an exergy-based loss method (LM) for assessing heat recovery steam generators (HRSGs) performance. First, energy and exergy analyses are applied to one HRSG unit in an existing combined cycle power plant. Then, the calculated exergy destructions are further split into avoidable and unavoidable parts. The sources of inefficiency consist of three energy and exergy loss terms and two exergy destruction terms. The loss terms are associated with the release of the exhaust gas to the atmosphere, Carbon Monoxide formation, and the heat loss from the casing, while the destruction terms represent exergy destruction within the duct burner and the heat transfer unit. The advanced exergy analysis was conducted based on a realistic perspective, considering the integrated operation of both subcomponents. Results reveal that the main source of inefficiency corresponds to the losses associated with the exhaust gas from the stack. Moreover, utilizing semi-ideal heat exchangers can avoid a considerable part (18.9%) of the exergy destruction in the heat transfer unit. The HRSG exergy efficiency is obtained by 71.7% and can be increased to 75.3% in unavoidable operating conditions.

Mathematical modeling of mass, heat and fluid flow in a reverberatory furnace for melting nickel-containing raw materials

The article presents analytical results on the use and distribution of energy in reverberatory furnaces with medium pressure gas burners to melt nickel-containing raw materials, by means of a numerical simulation of the furnace’s combustion space. The combustion flow and radiation of a reverberatory furnace powered by natural gas have been calculated and validated. The chemical composition of natural gas makes it the cleanest of fossil fuels, for this reason its use increases worldwide. The higher hydrogen/carbon ratio in its composition, compared to other fossil fuels, causes combustion to emit less CO2 per unit of energy produced. The flue gas outlet duct and medium pressure burners are represented and located as in a typical design to determine the effect on the efficiency of the reverberatory furnace. The results show the temperature field, the mass fraction of oxygen and fuel within the furnace’s combustion space and the comparison between the theoretical and practical efficiency of a furnace.

Multi-Objective Evolutionary Optimization & 4E analysis of a bulky combined cycle power plant by CO2/ CO/ NOx reduction and cost controlling targets

The 4E analysis is utilized on a bulky combined cycle power plant (CCPP) with a dual pressure recovery boiler and an additional duct burner. Multi-objective evolutionary optimizations have been applied to obtain the best state of the heat recovery steam generator (HRSG), saturated temperature, cost reduction, and carbon dioxide emission, simultaneously. For the validation, the authentic data has been collected from an implemented CCPP. This comprehensive study has been performed to perceive the relation between the most significant parameters on the performance of CCPP. The main obtained results include five points. First, the thermal recovery boiler and combustion chamber have the highest exergy destruction among the power plant components. Second, the optimization based on the entire cycle at all temperatures has no economic justification, and its total exergy efficiency and cost are better than optimizations based on the recovery boiler and HRSG. Third, the value of the CCPP decision parameters is highly dependent on the ambient temperature. Therefore, it is not possible to apply the same value for CCPP at various temperatures. Fourth, the genetic algorithm improved the optimized cycle parameters by considering two objectives of the power plant costs reduction and CO2 emission. Fifth, the combined cycle with the nameplate function generates less NOx and monoxide than relative loads. Using such combined cycles with dual pressure recovery boiler and additional duct reduces the normalized Co2 emissions by 158.67kgMWh .

Power boosting of a combined cycle power plant in Jordan: An integration of hybrid inlet cooling & solar systems

Many developing countries like Jordan, suffer from the lack of natural resources required to supply their energy demand. As such, maximum utilization of the available energy and renewable resources becomes a necessity. ALQatrana powerplant in Jordan; operating on a combined cycle suffers from sensitivity to ambient air temperatures and the lack of full utilization of waste heat of the flue gas. In this work, the plant was simulated using the engineering equation solver, and the simulation was validated against the actual powerplant data. A cascade of absorption and mechanical chillers for inlet air cooling, along with a CSP system were proposed. These auxiliary systems were also simulated and validated against literature, then integrated with the actual power plant cycle. Results showed that using the hybrid system for inlet air cooling with a combined cycle, can be more appealing in terms of power boosting and economical profit, compared to using either alone. The proposed system showed a relative increase in power by 22.8%, a 4.3% increased efficiency, and a relative decrease in SFC by 8.4%, compared to the actual power plant. Moreover, due to the hybrid inlet air cooling unit, the system exhibited low sensitivity to variation in ambient temperatures; hence, a stable power augmentation with relative change of only 0.9% over the range of temperatures (10–50) ℃. Additionally, compared to a duct burner integration, the proposed system, led to 6.4 million dollars annual saving in fuel consumption, with a 15% less CO2 emission for equivalent power production. A comprehensive feasibility study was also performed; showing a return of investment period equal to 5.3 years, which is very promising.

Comprehensive Performance Analysis of the Turbofan With a Multi-Annular Rotating Detonation Duct Burner

Abstract The performance analysis of mixed-exhaust turbofan engine with multi-annular rotating detonation duct burner (RDDB) is conducted for the first time, considering that the flow path of the bypass duct is ideal for a rotating detonation combustor (RDC). The configuration of the multi-annular rotating detonation combustor is constructed aiming at the advantages of a wider operation range and uniform outlet parameters over the single-annular one. Then, a parametric analysis model of the mixed-exhaust turbofan engine with a rotating detonation duct burner is developed. Thereafter, the effects of duct burner parameters on the engine performance and operating characteristics are investigated. The mixed-exhaust turbofan engine with a rotating detonation duct burner shows superior overall performance to that of one with an isobaric afterburner (ICAB) over a wide operation range. The separate-exhaust rotating detonation duct burner can hold characteristics that are higher than those of the mixed-exhaust one at lower values of fan pressure ratio, while the mixed-exhaust one corresponds to lower values of turbine inlet temperature. When the rotating detonation duct burner is “on,” the low-pressure rotor operating line moves toward the surge line on the low corrected shaft speed side but away from the surge line on the high corrected shaft speed side.

Multi-objective linear regression based optimization of full repowering a single pressure steam power plant

Full repowering of Be'sat steam power plant has been studied in this work. The methodology is used to simulate the new cycle according to its principal specifications and to optimize it based on the objective functions. Objective functions are electricity cost per kWh and exergy efficiency. These parameters are functions of the pinch and approach point temperature differences at high and low pressure points and at the pre-heater in the heat recovery steam generator (HRSG), steam turbine inlet flow rate, gas turbine (GT) isentropic efficiency, air compressor isentropic efficiency and compressor pressure ratio. Finally, considering the introduced objective functions, it is tried to achieve the most optimized techno-economic characteristics for Be'sat power plant repowering cycle using the genetic algorithm with two scenarios of single and multi-objective optimizations. The results show that the efficiencies of the repowered cycle are 52.59% and 51.3% for two cases of unfired and fired duct burners, respectively.

Off-design performance evaluation of Hassi R’Mel ISCC power plant

ABSTRACTThe paper presents a thermodynamic analysis of an existing ISCC power plant when running at off-design operation conditions. The off-design regime is due to changes in air temperature and DNI. The analysis is based on the results of calculations performed by the flow sheet programme ‘Cycle-Tempo’. For off-design modelling, some reasonable assumptions are adopted in regard to the operations of the turbomachines and heat exchangers. The power plant performance is examined when it is running following the operation strategy ‘saving mode’. The complementarily between the solar field and the duct burners (DBs), and the operation of the power plant, in terms of hourly net electricity output and thermal efficiency, are analysed on two representative days, a summer day and a winter day. The key parameters in the study are essentially the HTF mass flow rate, DB fuel consumption, thermal energies supplied by the solar field, and the DBs.

A new method to boost performance of heat recovery steam generators by integrating pinch and exergy analyses

Combined cycle power plants are gaining more attention throughout the world and their usage is increasing. This is because their efficiency is higher than simple Rankine or Brayton cycles. However, their efficiency could still increase. In this article, the driving force plot and exergy analysis are used to study the behavior of heat exchangers of a heat recovery steam generator in base case and off-design conditions. Based on the obtained results, a new method is proposed to improve performance of a heat recovery steam generator during the summers in which higher ambient temperature results in lower efficiency of plant. In this new method, hot flue gas at the heat recovery steam generator inlet is split which results in higher steam production in heat recovery steam generator. The results showed that the new proposed method is very beneficial and increases net output power of the plant. When split ratio increases from 2.5% to 15%, the power produced in steam turbine increases from 0.15 to 0.9 MW. It also increases exergy destruction of the heat recovery steam generator. This is due to higher mass flow rate of the produced steam and higher temperature difference between hot and cold streams. It is shown that this new method can reduce the negative effects of consuming more fuel in duct burner during the summers.

EFFECTS OF DUCT BURNER ON BOTTOMING CYCLE IN A COMBINED CYCLE POWER PLANT

In this study, thermodynamic modeling and exergoeconomic assessment of a Combined Cycle Power Plant (CCPP) with a Duct Burner (DB) was performed. Obtaining an optimum condition for the performance of a CCPP, using a DB after gas turbine was investigated by various researchers. DB is installed between gas turbine cycle and Rankine cycle of a CCPP to connect the gas turbine outlet to the Heat Recovery Steam Generator (HRSG) in order to produce steam for bottoming cycle. To find the irreversibility effect in each component of the bottoming cycle, a comprehensive parametric study is performed. In this regard, the effect of DB fuel flow rate on cost efficiency and economic of the bottoming cycle are investigated. To obtain a reasonable result, all the design parameters are kept constant while the DB fuel flow rate is varied. The results indicate that by increasing DB fuel flow rate, the investment cost and the efficiency of CCPP are increased. T-S diagram reveals that by using a DB, higher pressures steam in heat recovery steam generator has higher temperature while the low pressure is decreased. In addition, the exergy of flow gases in heat recovery steam generator increases. So, the exergy efficiency of the whole cycle was increased to around 6 percent, while the cost of the plant reduced by one percent.

Using Dynamic Simulation to Evaluate Attemperator Operation in a Natural Gas Combined Cycle With Duct Burners in the Heat Recovery Steam Generator

A generic training simulator of a natural gas combined cycle (NGCC) was modified to match operations at a real plant. The objective was to use the simulator to analyze cycling operations of the plant. Initial operation of the simulator revealed the potential for saturation conditions in the final high pressure superheater (HPSH) as the attemperator tried to control temperature at the superheater outlet during gas turbine loading and unloading. Subsequent plant operational data confirmed simulation results. Multiple simulations were performed during loading and unloading of the gas turbine to determine operational strategies that prevented saturation and increased the approach to saturation temperature. The solutions included changes to the attemperator temperature control setpoints and strategic control of the steam turbine (ST) inlet pressure control valve.

Techno-economic assessment of small-scale integrated biomass gasification dual fuel combined cycle power plant

This paper presents theoretical study of the concept of a small-scale combined cycle system composed of natural gas fired microturbine and Organic Rankine Cycle, integrated with thermal gasification of biomass. A conventional natural gas fired microturbine engine is applied within the system. Gaseous fuel from an updraught biomass gasification reactor is burned in duct burners located in the exhaust gas stream downstream of the turbine. Enthalpy of the combustion gases is used in the ORC cycle. The only product of the system is electric energy. Mathematical modelling of the system gives estimated values of achievable power and energy efficiency of the proposed setup. The plant can be considered as a robust technology for utilization of scattered biomass resources located in places where a natural gas network is available. The main issues addressed in the paper are: configuration of the ORC technology and allocation of generated electricity between natural gas and biomass. Energy and exergy allocation keys are demonstrated. An initial cash flow calculations are presented in order to assess financial performance of the plant.

Study of the effect of using duct burner on the functional parameters of the two repowered cycles through exergy analysis

Steam power plants have been extensively used in Iran for a long time, yet no specific step has been taken for promoting their performance. In this regard, full repowering is considered as a way to enhance the performance of steam power plants. Furthermore, because of the continental condition of Iran, duct burners can be used as a common strategy to compensate for power generation shortage caused by environmental conditions. In this study, the effect of using a duct burner on the full repowering of Be?sat Steam Cycle representing both single-and dual-pressure cycles was investigated based on exergy analysis. The results showed that by using the duct burner, due to the increase in the heat recovery steam generator inlet gas temperature, the general thermal efficiency of the combined cycle and the exergy efficiency of the combined cycle and heat recovery steam generator decreased. However, the results revealed an increase in the stack temperature and resulting exergy losses, steam flow and power generation.

Thermodynamics Analysis and Optimization of Abadan Combined Cycle Power Plant

Background/Objectives: The welfare and comfort of people in the world is directly related to consuming energy and its economic supply, which depends on quantity of energy resources. This has been turned into an important challenge with respect to rapid growth at level of request for energy in the world. Methods/Statistical analysis: In this multiobjective optimization that has been carried out by Non-Dominated Sorting Genetic Algorithm (NSGA-II), two objective functions of exergy efficiency and produced power costs composing of the cost of injected fuel into combustion chamber and duct burner as well as exergy loss cost and investment cost have been studied. Findings: The efficiency of Abadan combined cycle power plant depends on design parameters including gas turbine input temperature, compressor pressure ratio, and pinch point temperature and any change occurring in these parameters may lead to noticeable change in objective functions, so that the efficiency of this power plant is increased after optimization up to 7.12 % and heat rate is correspondingly reduced from 7503 (kJ/kWh) to 7149 (kJ/kWh). Similarly, exergy destruction in total system shows 8.37 reduction. Applications/Improvements: In this research Abadan combined cycle power plant has been perfectly modeled in terms of thermodynamics and the given results were compared with output data from Thermo-Flow Software in order to ensure the validity of the modeling code.

Parametric techno-economic studies of coal/biomass co-gasification for IGCC plants with carbon capture using various coal ranks, fuel-feeding schemes, and syngas cooling methods

Summary Because of biomass's limited supply (as well as other issues involving its feeding and transportation), pure biomass plants tend to be small, which results in high production and capital costs (per unit power output) compared with much larger coal plants. Thus, it is more economically attractive to co-gasify biomass with coal. Biomass can also make an existing plant carbon-neutral or even carbon-negative if enough carbon dioxide is captured and sequestered (CCS). As a part of a series of studies examining the thermal and economic impact of different design implementations for an integrated gasification combined cycle (IGCC) plant fed with blended coal and biomass, this paper focuses on investigating various parameters, including radiant cooling versus syngas quenching, dry-fed versus slurry-fed gasification (particularly in relation to sour-shift and sweet-shift carbon capture systems), oxygen-blown versus air-blown gasifiers, low-rank coals versus high-rank coals, and options for using syngas or alternative fuels in the duct burner for the heat recovery steam generator (HRSG) to achieve the desired steam turbine inlet temperature. Using the commercial software, Thermoflow®, the case studies were performed on a simulated 250-MW coal IGCC plant located near New Orleans, Louisiana, and the coal was co-fed with biomass using ratios ranging from 10% to 30% by weight. Using 2011 dollars as a basis for economic analysis, the results show that syngas coolers are more efficient than quench systems (by 5.5 percentage points), but are also more expensive (by $500/kW and 0.6 cents/kW h). For the feeding system, dry-fed is more efficient than slurry-fed (by 2.2–2.5 points) and less expensive (by $200/kW and 0.5 cents/kW h). Sour-shift CCS is both more efficient (by 3 percentage points) and cheaper (by $600/kW or 1.5 cents/kW h) than sweet-shift CCS. Higher-ranked coals are more efficient than lower-ranked coals (2.8 points without biomass, or 1.5 points with biomass) and have lower capital cost (by $600/kW without using biomass, or $400/kW with biomass). Finally, plants with biomass and low-rank coal feedstock are both more efficient and have lower costs than those with pure coal: just 10% biomass seems to increase the efficiency by 0.7 points and reduce costs by $400/kW and 0.3 cents/kW h. However, for high-rank coals, this trend is different: the efficiency decreases by 0.7 points, and the cost of electricity increases by 0.1 cents/kW h, but capital costs still decrease by about $160/kW. Copyright © 2016 John Wiley & Sons, Ltd.

Advanced exergy and environmental analyses and multi objective optimization of a real combined cycle power plant with supplementary firing using evolutionary algorithm

This paper deals with an advanced exergy analysis and optimization of a real CCPP (combined cycle power plant) with DBs (duct burners) located in Iran. The endogenous/exogenous exergy destruction parts of each component as well as their combinations with avoidable/unavoidable parts are determined. A parametric study is carried out to assess the sensitivity of total avoidable exergy destruction and CO2 emission to TIT (turbine inlet temperature), compressor pressure ratio (rc) and DB fuel mass flow rate (m˙DB). Parametric results reveal that the increments in TIT and rc improve the CO2 emissions by about 6.8% and 17%, respectively and the total avoidable exergy destruction rate increases within 19% when rc is in the range of 9–14. In addition, NSGA-II (Non-dominated Sort Genetic Algorithm-II) is applied to obtain the final solutions in the multi-objective optimization of the CCPP. The optimum value of total avoidable exergy destruction rate and CO2 emission indicates 10.6% and 8.3% improvements, respectively, relative to the base case. Furthermore, the values of TIT and m˙DB decrease to 1.7% and 32.5%, respectively and rc increases 38% compared with the base case.

Assessment of a Rich-Burn, Quick-Mix, Lean-Burn–Based Supplemental Burner System in a Vitiated Air Stream

ABSTRACTIn an effort to increase overall efficiency of distributed power generation systems, strategies to optimize the combination of cooling or heating with power (CCHP) are desired. One significant issue in implementing a CCHP system is that electrical loads and heating/cooling loads are rarely synchronized. Duct burners are frequently used in large systems to provide additional heat when the waste heat available from the prime mover does not meet the needs of the heat recovery device. Duct burners must operate on vitiated oxidizer streams, which can result in poor stability, elevated emissions, or both. Rich-burn, quick-mix, lean-burn (RQL) style combustors have been shown to provide low emission and high stability in lean burn gas turbine applications, but have not been considered for duct burner applications. To this point, the current work carries out an experimental investigation to assess the merits of using an RQL style combustor in a duct burner application. A systematic evaluation of several RQL burner configurations revealed that a lean-zone-to-rich-zone air mass ratio of 2.5 produced the lowest emissions of NOx and CO at a fixed fuel-to-air ratio. However, this reduction in emissions was accompanied with a decrease in the stability range of the burner. Furthermore, decreasing the amount of swirl in the rich zone was found to decrease NOx emissions. It was observed that oxygen concentration of the oxidizer had a more significant effect on the emission of CO than any configuration of the burner.

Investigating the effect of duct burner fuel mass flow rate on exergy destruction of a real combined cycle power plant components based on advanced exergy analysis

In this research, an advanced exergy analysis of a real combined cycle power plant (CCPP) with supplementary firing is investigated. The endogenous/exogenous irreversibilities of each component and their combination with avoidable/unavoidable irreversibilities are identified. Furthermore, parametric study of the total exergy destruction, thermal and exergetic efficiencies and different parts of exergy destruction of each component are examined as a function of duct burner fuel mass flow rate (ṁDB). It is revealed that the avoidable exergy destruction of CCPP decreases within 23.9% while its unavoidable part increases by about 50% as ṁDB increases. In addition, the endogenous avoidable exergy destruction of CCPP gets 3 times while its exogenous part of avoidable is reduced within 86% by increasing ṁDB. It is found that the growth of ṁDB elevates the potential improvement of high pressure superheater (HP.SUP), low pressure evaporator (LP.EVAP) and low pressure steam turbine (LP.ST), and decreases the avoidable exergy destruction of the high pressure evaporator (HP.EVAP) and duct burner (DB). Moreover, the increment of ṁDB, decreases the unavoidable exergy destruction just in high pressure steam turbine (HP.ST) and dearator (DEAR) by about 8.2% and 5%, respectively, and increases the exogenous of avoidable exergy destruction of DB (ĖD,DBAV) within 166%. It means that the effect of other components irreversibilities on avoidable exergy destruction of DB is increased while inefficiency of this component has considerable decrement on its avoidable exergy destruction.