Cogeneration Power Plant Research Articles

Internal leakage of plate heat exchangers caused by cooperation of pitting, crevice corrosion, and fretting

Abstract Comprehensive failure analysis was carried out on internal leakage of 316L plates in a plate heat exchanger operated in a co-generation power plant. Causes of failure were bowl-like perforations that were regularly distributed on the crossing contact points (CCPs) between zigzag peaks of neighboring corrugated plates. Other potential failure mechanisms were ruled out through a process of elimination, although some of the observed features increased the difficulty in the failure analysis. The bowl-like perforations are induced by the cooperation of pitting, crevice corrosion, and fretting. The pressure of high-temperature hot water (HTHW) is much higher than that of low-temperature hot water (LTHW), and this results in a narrower crevice and compressive stress between CCPs at LTHW sides of corrugated plates. A narrower crevice assembles a lot of corrosive elements such as Cl−, and compressive stress induces fretting with a fluctuation in water pressure. Where the surface passive film is damaged by fretting, CCPs first suffer crevice corrosion and pitting. In the process of perforation growth, the combination of pitting, crevice corrosion, and fretting had the primary role in the circumferential direction, whereas both pitting and crevice corrosion had the main role in the depth direction. Thus, pits were corroded more severely in the circumferential direction, resulting in a bowl-shape perforation or pit.

Performance Analysis of Integrated Solar Tower With a Conventional Heat and Power Co-Generation Plant

Abstract This paper presents the results of a thermo-economic analysis of integrating solar tower (ST) with heat and power cogeneration plants that is progressively being installed to produce heat and electricity to operate absorption refrigeration systems or steam for industrial processes. The annual performance of an integrated solar-tower gas-turbine-cogeneration power plant (ISTGCPP) with different sizes of gas turbine and solar collector's area have been examined and presented. Thermoflex + PEACE software's were used to thermodynamically and economically assess different integration configurations of the ISTGCPP. The optimal integrated solar field size has been identified and the pertinent reduction in CO2 emissions due to integrating the ST system is estimated. For the considered cogeneration plant (that is required to produce 81.44 kg/s of steam at 394 °C and 45.88 bars), the study revealed that (ISTGCPP) with gas turbine of electric power generation capacity less than 50 MWe capacities have more economic feasibility for integrating solar energy. The levelized electricity cost (LEC) for the (ISTGCPP) varied between $0.067 and $0.069/kWh for gas turbine of electric power generation capacity less than 50 MWe. Moreover, the study demonstrated that (ISTGCPP) has more economic feasibility than a stand-alone ST power plant; the LEC for ISTGCPP is reduced by 50–60% relative to the stand-alone ST power plant. Moreover, a conceptual procedure to identify the optimal configuration of the ISTGCPP has been developed and presented in this paper.

The Investigation of Fuel Type Influence on the Energy Indicators of the Electrochemical Generator in the Cogeneration Unit

The paper presents a generic technique to calculate the consumption of synthetic gas and fuel for the specified electrical power, temperature in the anode fuel utilization factor, specific expenses of fuel equivalent to develop electric and thermal energy, power efficiency for various natural fuels (methane, coal, petroleum products, etc.) and synthesized ones (methanol, ethanol, etc.) in synthesis gas with subsequent use of it in the SOFC. The paper researches into the influence of fuel types: hydrogen, methane, motor diesel fuel, ethanol, gasoline and methanol – on fuel utilization factor, specific expenses for the production of electrical and thermal energy, efficiencies of the catalytic burner, fuel cell solid-oxide battery and electrochemical generator. The overall level of fuel utilization for the cogeneration power plant based on SOFC with hydrogen fuel and methane surpasses the level of modern combined-cycle cogeneration plant, and with diesel, ethanol, gasoline, and methanol surpasses the level of cogeneration combined heat and power plant CHPP on the basis of the internal combustion engine. The investigation has shown that the best fuel is hydrogen and the worst is methanol on the level of energy performance. For hydrogen, fuel utilization factor and specific expenses of fuel for production of electric and thermal energy releasing in heat networks equal to 1; 0.122 kg equivalent fuel/kWh and 34 kg of equivalent fuel/GJ, respectively, while for methanol, these indicators equal to 0.359; 0.475 kg equivalent fuel/kWh and 83,7 kg of equivalent fuel/GJ. For other fuel types, these energy indicators lie between the specified values.

Numerical modeling of an automotive derivative polymer electrolyte membrane fuel cell cogeneration system with selective membranes

Cogeneration power plants based on fuel cells are a promising technology to produce electric and thermal energy with reduced costs and environmental impact. The most mature fuel cell technology for this kind of applications are polymer electrolyte membrane fuel cells, which require high-purity hydrogen.The most common and least expensive way to produce hydrogen within today's energy infrastructure is steam reforming of natural gas. Such a process produces a syngas rich in hydrogen that has to be purified to be properly used in low temperature fuel cells. However, the hydrogen production and purification processes strongly affect the performance, the cost, and the complexity of the energy system.Purification is usually performed through pressure swing adsorption, which is a semi-batch process that increases the plant complexity and incorporates a substantial efficiency penalty. A promising alternative option for hydrogen purification is the use of selective metal membranes that can be integrated in the reactors of the fuel processing plant. Such a membrane separation may improve the thermo-chemical performance of the energy system, while reducing the power plant complexity, and potentially its cost. Herein, we perform a technical analysis, through thermo-chemical models, to evaluate the integration of Pd-based H2-selective membranes in different sections of the fuel processing plant: (i) steam reforming reactor, (ii) water gas shift reactor, (iii) at the outlet of the fuel processor as a separator device. The results show that a drastic fuel processing plant simplification is achievable by integrating the Pd-membranes in the water gas shift and reforming reactors. Moreover, the natural gas reforming membrane reactor yields significant efficiency improvements.

Modeling of a small parabolic trough plant based in direct steam generation for cogeneration in the Chilean industrial sector

The concentrated solar power technology used in schemes of cogeneration for the production of power and heat, or power and cooling is an interesting option to develop in Chile, mainly due to the high solar potential. Besides, cogeneration is an option to face the demand for energy in terms of electricity, industrial heat or cooling, which is increasing in Chile in recent years. A concentrated solar power cogeneration plant based in parabolic trough technology with a backup system of a biogas heater and a direct steam generation scheme is proposed. The cogeneration study considers two different plants, one for power and heat, and other for power and cooling, which were studied in Santiago, Chile. The results show a benefit in fossil fuels replacement when the cogeneration plant is compared to a conventional plant for production of industrial heat. In the case of cooling, electricity savings are achieved when the cogeneration plant is compared to a conventional vapor-compression system. The cooling demand can be supplied totally using an absorption chiller in the cogeneration scheme, reaching electricity energy saving of up to 99%. For cogeneration of power and heat the energy replacement in the industrial heat process are as minimum 69% depending on the demand and configuration of the plant, and can reach up to 100%. Finally, when the biogas heater is disconnected from the plant to consider a case only based in the concentrated solar power plant, the cogeneration scheme for cooling can reach an electricity saving of 4%. The cogeneration scheme for heat can reach an energy replacement of 14% as minimum.

Experience in Creation and Exploitation of Energetic and Energy-Technological Plants Based on Hydrothermal Oxidation of Aluminum

Present paper is devoted to the description of our recent experience in the creation and exploitation of energetic and energy-technological plants based on hydrothermal oxidation of aluminum. Two plants based on reactor for hydrothermal oxidation of aluminum were created for today. These are experimental co-generation power plant and energy-technological plant with hydrogen production rate of 10 and 100 nm3/hour respectively. The principle of operation of the reactor for hydrothermal oxidation as well as the plants based on such reactor is discovered in present paper.

Exergy Analysis of the Annual Operation of a Sugarcane Cogeneration Power Plant Assisted by Linear Fresnel Solar Collectors

In this work, the exergy analysis of two configurations of hybrid solar–sugarcane cogeneration power plant is proposed in order to evaluate the overall efficiency enhancement of the cycle. Solar thermal energy was coupled to a sugarcane cogeneration power plant localized on the tropical region of Brazil, in order to preheat the feeding water supplied to the steam generators and to reduce the fuel consumption during the sugarcane-harvesting season in order to stock the unused fuel for its use during the off-season. The exergy analysis of the cycle was proposed based on a thermodynamic model, which considered real operational states, and allowed to quantify the main parameters of performance, such as the solar-to-electricity (STE) efficiency, the power generation increasing, the percentage of fuel saved, and the exergy destruction rates of the equipment. The results showed that, under design conditions, almost 10% of fuel was saved, and the overall exergy destruction decreased 11% approximately. Additionally, as a result of the hourly analysis of the annual operation, it was found that the power plant operated 331 extra hours, 8.50 GWh of electricity were generated, and due to this fact, it has attained economic benefits for the operation of the sugarcane cogeneration power plant.

Quantifying coal power plant responses to tighter SO2 emissions standards in China

We evaluate the impact of China's new air pollution standards on sulfur dioxide (SO2) emissions by comparing newly available data from Continuous Emissions Monitoring Systems (CEMS) at coal power plants with satellite measures. First, we show that following the July 2014 deadline for implementing tighter emissions standards, stack concentrations of SO2 reported by CEMS declined by 13.9%. Second, on average the ratios of the declines of SO2 measures in the satellite data and the CEMS data are about 0.5. However, the degree of correspondence between the two data sources varies by policy stringency, with weak correspondence found in key regions facing the toughest new limits. Third, large plants achieved compliance earlier than small (typically) power and heat cogeneration plants. To achieve continued air quality improvement, our results suggest a need for increased scrutiny of emissions data quality and monitoring practices and clear long-term targets.

How best management practices affect emissions in gas turbine power plants—An important factor to consider when strengthening emission standards

ABSTRACTThe Beijing Municipal Environmental Protection Bureau (EPB) is considering strengthening the Emission Standard of Air Pollutants for Stationary Gas Turbines, originally published in 2011 (DB11/847–2011), with a focus on reducing nitrogen oxides (NOx) emissions. A feasibility study was conducted to evaluate the current operation of 12 existing combined-cycle gas turbine power plants and the design of two new plants in Beijing and their emission reduction potential, in comparison with a state-of-the-art power plant in California. The study found that best management practices (BMPs) could potentially improve the emission level of the power plants, and should be implemented to minimize emissions under current design characteristics. These BMPs include (1) more frequent tuning of turbine combustors; (2) onsite testing of natural gas characteristics in comparison to turbine manufacturer’s specifics and tuning of turbine to natural gas quality; (3) onsite testing of aqueous ammonia to ensure adequate ammonia concentration in the mixed solution, and the purity of the solution; (4) more careful inspection of the heat recovery steam generator (HRSG), and the selective catalytic reduction (SCR) during operation and maintenance; (5) annual testing of the catalyst coupon on the SCR to ensure catalyst effectiveness; and (6) annual ammonia injection grid (AIG) tuning. The study found that without major modification to the plants, improving the management of the Beijing gas turbine power plants may potentially reduce the current hourly average NOx emission level of 5–10 parts per million (ppm; ranges reflects plant variation) by up to 20%. The exact improvement associated with each BMP for each facility requires more detailed analysis, and requires engagement of turbine, HRSG, and SCR manufacturers. This potential improvement is an important factor to consider when strengthening the emission standard. However, note that with the continuous needs of improving air quality within the area, more expensive control measures, such as retrofitting the turbines or the HRSGs, may be considered.Implications: This study analyzed the potential emission reductions associated with implementing the best management practices (BMPs) on the combined cycle and cogeneration power plants in Beijing. It determined that implementing the BMPs could potentially achieve up to 580 metric tonnes, or 0.6%, reductions of all NOx emissions in Beijing. Many other cities in China and Asia battling air quality issues may find the information useful in order to evaluate the emission reduction potential of their own gas turbine power plants.

Gimazetdinov R.R., Malozemov A.A., Kukis V.S. Diesel-generator plant with the recovery of waste heat of the piston engine

The subject of the investigation was the waste heat recovery system of a small-scale heat electropower station that can be used as stationary and primary, reserve or additional source of electrical and thermal energy. The object of the investigation was the waste heat recovery system of the diesel engine D 180 and the small-scale heat electropower station on the basis of the diesel generator plant DGU-100C produced by JSC «ChTZ». The aim of the investigation was an experimental estimation of the efficient use of the diesel engine’s waste heat recovery system. The recovery system was consisted of an original heat exchanger for the recovery of the waste heat of the diesel engine’s cooling system, the waste heat of the lubricating system, the centers of which is made in a common housing, and the heat exchanger for the recovery of the exhaust gases waste heat from the diesel engine (pre-heater boiler PZD-600). The article presents the small-scale heat electropower station’s arrangement with the waste heat recovery system, the original heat exchanger arrangement and a scheme of the small-scale heat electropower station with the waste heat recovery system. The principle of operation of the proposed system is described. In comparison with the known constructions, in the proposed cogeneration power plant there is no need to separately regulate the temperature of the cooling liquid and the lubricating oil at the inlet to the piston internal combustion engine and the necessity to use an additional liquid-oil heat exchanger or oil cooler in the operation of the cogeneration plant without thermal load. Collectively, it was ensured a reduction of the complexity, material consumption and overall dimensions of the recovery system and the cogeneration power plant in general. The absolute economic effect from the using of the waste heat recovery system is 240…300 thousand rubles for the engine life, specific - 22…28 rubles/h. The payback period of the waste heat recovery system is less than a year. The obtained results convincingly indicate the economic feasibility of implementing the proposed system of waste heat recovery of the diesel engine D 180 of a small-scale heat electropower station based on the DGU-100S.

Thermo-economics analysis of a cane bio-refinery

ABSTRACTA cane bio-refinery consists of the following components: sugar mill, distillery, refinery and cogeneration power plant. The latter supplies electricity and process heat needed by the other components of the bio-refinery. Although process heat and electricity have the same units of energy, they are of different quality levels. Appropriate attention can be directed to those components causing major exergy loss. Furthermore, a device/system can be exergy efficient but may not be cost-effective. Thus, the financial implications need also to be assessed. The performance of an existing cane bio-refinery was assessed on the basis of thermo-economics analysis. It was found that the addition of an evaporator of the falling film thin type in the sugar mill would not only reduce the exergy loss but would also generate more revenues. A better-informed decision could be made for the optimisation of a bio-refinery.

Energy-exergy-economic (E3) analysis of stand-alone solar thermal cogeneration power plant

Concentrating solar power (CSP) based solar cogeneration plants are more energy efficient compared to single purpose power plants. In this paper, energy, exergy and economic analysis have been carried out for the stand-alone solar thermal co-generation power plant (SASTCPP), which is based on Rankine cycle. Both direct and indirect steam generation is adopted for the comparative E3 analysis. To achieve high energy efficiency, back pressure steam turbine with regenerative feed water heating is incorporated in power block. Reference cogeneration power plant has a capacity of 50 MWth. levelised cost of electricity (LCOE) associated to SASTCPP is calculated with three different cost allocation approach – direct, equivalent fuel consumption, and exergy approach. The observed exergy efficiency (33–35%) is comparatively less than energy efficiency (62–70%) and the maximum exergy destruction takes place within the solar field. Minimum LCOE calculated as Indian rupees (INR) 5.46 with direct steam generation (DSG).

Bagasse Ash for Manufacturing Construction Products

In India large scale sugar industry was developed along with cogeneration power plant. The cogeneration plant is uses bagasse as a fuel. Sugar cane bagasse is a fibrous waste product of sugar refining industry. The bagasse burns and produces huge amount of ash which easily flies in air. This paper presents the current manufacturing processes and economics of bricks, measured and evaluated physical, chemical and mechanical soil properties of bagasse ash and construction products. The experimental evaluation of the bagasse brick with bagasse ash percentage varies from 20,30,40,50 and 60% and tested for moisture holding and compressive test. It is observed that the maximum compressive stress obtained is 1.272 N/mm2.Further the chemical analysis is carried out with XRD. The bricks are baked at temperature 600to 850OC and baking time from 6to 8 Hrs.

Exergo-economic analysis of parabolic trough integrated cogeneration power plant

Cogeneration plant produces heat and electricity simultaneously, and have a great potential towards best use of primary energy resources as compared to other plants, which produces heat and electricity separately. Parabolic trough integrated cogeneration power plant (PTICPP) is one of the attractive alternatives to utilising solar energy in an efficient manner. The economically viable PTICPP could bring an opportunity for its utilisation at large scale. Therefore, estimation of the levelised cost of electricity (LCE) is done by two different rational cost apportionment method namely; lost-kilowatt and exergy method. To achieve the objective of this paper, a reference PTICPP having a capacity of 20 MWe and 61.94 MWth is designed, and comprehensive thermal performance of reference plant is analysed at the variable amount of irradiation. In Indian climatic condition, the minimum estimated LCE are 0.127 $/kWh and 0.114 $/kWh respectively by lost-kilowatt and exergy method.

Control System of Cogeneration Power Plant at Partial Electrical Loads

Control System of Cogeneration Power Plant at Partial Electrical Loads

Energy-exergy-economic (E3) analysis of stand-alone solar thermal cogeneration power plant

Energy-exergy-economic (E3) analysis of stand-alone solar thermal cogeneration power plant

Exergo-economic analysis of parabolic trough integrated cogeneration power plant

Cogeneration plant produces heat and electricity simultaneously, and have a great potential towards best use of primary energy resources as compared to other plants, which produces heat and electricity separately. Parabolic trough integrated cogeneration power plant (PTICPP) is one of the attractive alternatives to utilising solar energy in an efficient manner. The economically viable PTICPP could bring an opportunity for its utilisation at large scale. Therefore, estimation of the levelised cost of electricity (LCE) is done by two different rational cost apportionment method namely; lost-kilowatt and exergy method. To achieve the objective of this paper, a reference PTICPP having a capacity of 20 MWe and 61.94 MWth is designed, and comprehensive thermal performance of reference plant is analysed at the variable amount of irradiation. In Indian climatic condition, the minimum estimated LCE are 0.127 $/kWh and 0.114 $/kWh respectively by lost-kilowatt and exergy method.

Feasibility of mini combined cycles for naval applications

The objective of energy production with low environmental impact will have, in the near future, high potential of development also for naval applications. The containment of pollutant emissions can be achieved by the combined use of an innovative mini gas-steam combined cycle with thermal energy cogeneration to feed the ship thermal utilities, in place of the current Diesel engine application, and liquefied natural gas as fuel (LNG). The present work is focused on the definition of the architecture of the plant, by selecting optimal distribution of pressure and temperature and repartition of power between Gas Turbine (GT), Steam Turbine (ST) and thermal utilities, as well as on the choice and sizing of the individual components. The main purpose is the definition of a compact, high efficiency, system. The proposed basic mini-cycle ranges from 2 MW to 10 MW electric power. Thanks to the combined heat and power cogeneration plant adopted, for an overall electrical efficiency of about 30%, a total return (thermal + electricity) of about 75% can be achieved. An example of plant providing large power, in a partially modular arrangement is also proposed.

Entropy Generation Calculation of a Turbofan Engine: A Case of CFM56-7B

Abstract Entropy generation and energy efficiency of turbofan engines become greater concern in recent years caused by rises fuel costs and as well as environmental impact of aviation emissions. This study describes calculation of entropy generation for a two-spool CFM56-7B high-bypass turbofan widely used on short to medium range, narrow body aircrafts. Entropy generation and power analyses are performed for five main engine components obtaining temperature-entropy, entropy-enthalpy, pressure-volume diagrams at ≈121 kN take-off thrust force. In the study, maximum entropy production is determined to be 0.8504 kJ/kg K at the combustor, while minimum entropy generation is observed at the low pressure compressor component with the value of 0.0025 kJ/kg K. Besides, overall efficiency of the turbofan is determined to be 14 %, while propulsive and thermal efficiencies of the engine are 35 % and 40 %, respectively. As a conclusion, this study aims to show increase of entropy due to irreversibilities and produced power dimension in engine components for commercial turbofans and aero-derivative cogeneration power plants.

Performance assessment of a hybrid SOFC/MGT cogeneration power plant fed by syngas from a biomass down-draft gasifier

Hybrid systems combine two or more power generating devices and make use of the synergism to generate maximum power and offer very high efficiencies.The aim of this work is to investigate the performance achievable from a small-scale hybrid power plant based on the integration between a micro gas turbine (MGT) and a solid oxide fuel cell (SOFC) fed by the syngas generated by a biomass downdraft gasifier (BG). The thermal energy needed to reach the turbine inlet temperature is supplied by the exhausts coming from a catalytic burner in which the SOFC anode and cathode off-gases are burnt.The hybrid BG-SOFC/MGT plant, based on a simplified configuration and realized considering components commercially available, is designed for optimizing not only the electric power generation, but also the thermal power production, in accordance with the promotion of decentralized CHP plants.The performance assessment has been carried out by means of a numerical model, based on thermodynamic/thermochemical approaches and realized by integrating the models of each plant section, developed by using the Aspen Plus software package. The models validation, performed by using experimental data, demonstrates that the results produced are close to those obtained from each unit, so that the overall integrated model can provide a sufficiently accurate prediction of the expected actual hybrid power plant.The effects of some operating parameters on cogeneration performances, such as the MGT pressure ratio and the S/C (steam to carbon) in the SOFC unit, have been evaluated and analyzed.Results show that the best performances are achieved by assuming the MGT pressure ratio equal to 4.5 and the S/C equal to 0. In this case the electric power is 262kW (SOFC supplies 180kW), the thermal power is 405kW and the electric (AC) and cogeneration efficiencies are 35% and 88%, respectively.