Optimization study of large-scale low-grade energy recovery from conventional Rankine cycle power plants

The world market for systems for power recovery from low-grade heat sources is of the order of £1 billion per annum. Many of these sources are hot liquids or gases from which conventional power systems convert less than 2.5 per cent of the available heat into useful power when the fluid is initially at a temperature of 100° C rising to 8–9 per cent at an initial temperature of 200°C. Consideration of the maximum work recoverable from such single-phase heat sources leads to the concept of an ideal trilateral cycle as the optimum means of power recovery. The trilateral flash cycle (TFC) system is one means of approaching this ideal which involves liquid heating only and two-phase expansion of vapour. Previous work related to this is reviewed and details of analytical studies are given which compare such a system with various types of simple Rankine cycle. It is shown that provided two-phase expanders can be made to attain adiabatic efficiencies of more than 75 per cent, the TFC system can produce outputs of up to 80 per cent more than simple Rankine cycle systems in the recovery of power from hot liquid streams in the 100–200°C temperature range. The estimated cost per unit net output is approximately equal to that of Rankine cycle systems. The preferred working fluids for TFC power plants are light hydrocarbons.

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1-D Model Analysis of Tesla Turbine for Small Scale Organic Rankine Cycle (ORC) System

Volume 3: Coal, Biomass and Alternative Fuels; Cycle Innovations; Electric Power; Industrial and Cogeneration Applications; Organic Rankine Cycle Power Systems ◽

10.1115/gt2017-63797 ◽

2017 ◽

Author(s):

Jian Song ◽

Chun-wei Gu

Keyword(s):

Large Scale ◽

Low Cost ◽

Organic Rankine Cycle ◽

Axial Flow ◽

Rankine Cycle ◽

Expansion Ratio ◽

Working Fluid ◽

Small Scale ◽

Low Grade ◽

D Model

Energy shortage and environmental deterioration are two crucial issues that the developing world has to face. In order to solve these problems, conversion of low grade energy is attracting broad attention. Among all of the existing technologies, Organic Rankine Cycle (ORC) has been proven to be one of the most effective methods for the utilization of low grade heat sources. Turbine is a key component in ORC system and it plays an important role in system performance. Traditional turbine expanders, the axial flow turbine and the radial inflow turbine are typically selected in large scale ORC systems. However, in small and micro scale systems, traditional turbine expanders are not suitable due to large flow loss and high rotation speed. In this case, Tesla turbine allows a low-cost and reliable design for the organic expander that could be an attractive option for small scale ORC systems. A 1-D model of Tesla turbine is presented in this paper, which mainly focuses on the flow characteristics and the momentum transfer. This study improves the 1-D model, taking the nozzle limit expansion ratio into consideration, which is related to the installation angle of the nozzle and the specific heat ratio of the working fluid. The improved model is used to analyze Tesla turbine performance and predict turbine efficiency. Thermodynamic analysis is conducted for a small scale ORC system. The simulation results reveal that the ORC system can generate a considerable net power output. Therefore, Tesla turbine can be regarded as a potential choice to be applied in small scale ORC systems.

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Evaluation of the washability characteristics of Khushab coal (Pakistani) by heavy media separation process

Energy & Environment ◽

10.1177/0958305x17714151 ◽

2017 ◽

Vol 28 (5-6) ◽

pp. 598-607 ◽

Cited By ~ 4

Author(s):

Hafiz Sana ◽

Sumaira Kanwal ◽

Javaid Akhtar ◽

Naseer Sheikh ◽

Shahid Munir

Keyword(s):

Energy Recovery ◽

Power Plants ◽

Calorific Value ◽

Environmental Issues ◽

Thermochemical Conversion ◽

Low Grade ◽

Particle Sizes ◽

Clean Coal ◽

Recovery Schemes ◽

Combustion Technique

The use of high-sulfur Pakistani coals can cause serious problems of slagging and fouling in thermochemical conversion reactors along with environmental issues like acid rain, etc. In this study, a pre-combustion technique, namely heavy media separation, is employed for the cleaning of low-grade Pakistani coal. Six crushed coal samples of different particle sizes were individually subjected to heavy media solutions of ZnCl2 of different specific gravities. It was found that the sample with a particle size of −6.25+4 mm at specific gravity of 1.4 produced the optimum float product as clean coal, showing 83.53% yield of clean coal with 1.24% ash and 1.0% sulfur contents. An overall reduction of 91.68% in ash and 86.11% sulfur contents was obtained. Moreover, up to 19.3% enhancement of gross calorific value was achieved. The resultant clean coal can be used in various energy recovery schemes in Pakistan such as coal-fired power plants and cement industries.

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Low Temperature Heat Recovery Through Integration of Organic Rankine Cycle and CO2 Removal Systems in a NGCC

Volume 2: Dynamics, Vibration and Control; Energy; Fluids Engineering; Micro and Nano Manufacturing ◽

10.1115/esda2014-20324 ◽

2014 ◽

Author(s):

Vittorio Tola ◽

Matthias Finkenrath

Keyword(s):

Low Temperature ◽

Heat Recovery ◽

Power Plants ◽

Organic Rankine Cycle ◽

Rankine Cycle ◽

Low Grade ◽

Co2 Removal ◽

Temperature Heat ◽

Temperature Levels ◽

Low Grade Heat

Reducing carbon dioxide (CO2) emissions from power plants utilizing fossil fuels is expected to become substantially more important in the near- to medium-term due to increasing costs associated to national and international greenhouse gas regulations, such as the Kyoto protocol and the European Union Emission Trading Scheme. However, since net efficiency penalties caused by capturing CO2 emissions from power plants are significant, measures to reduce or recover efficiency losses are of substantial interest. For a state-of-the-art 400 MW natural gas-fueled combined cycle (NGCC) power plant, post-combustion CO2 removal based on chemical solvents like amines is expected to reduce the net plant efficiency in the order of 9–12 percentage points at 90% overall CO2 capture. A first step that has been proposed earlier to improve the capture efficiency and reduce capture equipment costs for NGCC is exhaust gas recirculation (EGR). An alternative or complementary approach to increase the overall plant efficiency could be the recovery of available low temperature heat from the solvent-based CO2 removal systems and related process equipment. Low temperature heat is available in substantial quantities in flue gas coolers that are required upstream of the CO2 capture unit, and that are used for exhaust gas recirculation, if applied. Typical temperature levels are in the order of 80°C or up to 100 °C on the hot end. Additional low-grade heat sources are the amine condenser which operates at around 100–130 °C and the amine reboiler water cooling that could reach temperatures of up to 130–140°C. The thermal energy of these various sources could be utilized in a variety of low-temperature heat recovery systems. This paper evaluates heat recovery by means of an Organic Rankine Cycle (ORC) that — in contrast to traditional steam Rankine cycles — is able to convert heat into electricity efficiently even at comparably low temperatures. By producing additional electrical power in the heat recovery system, the global performance of the power plant can be further improved. This study indicates a theoretical entitlement of up to additional 1–1.5 percentage points in efficiency that could be gained by integrating ORC technology with a post-combustion capture system for natural gas combined cycles. The analysis is based on fundamental thermodynamic analyses and does not include an engineering- or component-level design and feasibility analysis. Different ORC configurations have been considered for thermal energy recovery at varying temperature levels from the above-mentioned sources. The study focuses on simultaneous low-grade heat recovery in a single ORC loop. Heat recovery options that are discussed include in series, in parallel or cascaded arrangements of heat exchangers. Different organic operating fluids, including carbon dioxide, R245fa, and N-butane were considered for the analysis. The ORC performance was evaluated for the most promising organic working fluid by a parametric study. Optimum cycle operating temperatures and pressures were identified in order to evaluate the most efficient approach for low temperature heat recovery.

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Addressing Industrial Waste Heat Supply Variability With Organic Rankine Cycle Systems Incorporating Thermal Energy Storage

10.21203/rs.3.rs-658624/v1 ◽

2021 ◽

Author(s):

Bipul Krishna Saha ◽

Basab Chakraborty ◽

Rohan Dutta

Keyword(s):

Power Generation ◽

Energy Storage ◽

Thermal Energy ◽

Thermal Energy Storage ◽

Power Plants ◽

Waste Heat ◽

Organic Rankine Cycle ◽

Rankine Cycle ◽

Working Fluid ◽

Low Grade

Abstract Industrial low-grade waste heat is lost, wasted and deposited in the atmosphere and is not put to any practical use. Different technologies are available to enable waste heat recovery, which can enhance system energy efficiency and reduce total energy consumption. Power plants are energy-intensive plants with low-grade waste heat. In the case of such plants, recovery of low-grade waste heat is gaining considerable interest. However, in such plants, power generation often varies based on market demand. Such variations may adversely influence any recovery system's performance and the economy, including the Organic Rankine Cycle (ORC). ORC technologies coupled with Cryogenic Energy Storage (CES) may be used for power generation by utilizing the waste heat from such power plants. The heat of compression in a CES may be stored in thermal energy storage systems and utilized in ORC or Regenerative ORC (RORC) for power generation during the system's discharge cycle. This may compensate for the variation of the waste heat from the power plant, and thereby, the ORC system may always work under-designed capacity. This paper presents the thermo-economic analysis of such an ORC system. In the analysis, a steady-state simulation of the ORC system has been developed in a commercial process simulator after validating the results with experimental data for a typical coke-oven plant. Forty-nine different working fluids were evaluated for power generation parameters, first law efficiencies, purchase equipment cost, and fixed investment payback period to identify the best working fluid.

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Energy Recovery Improvement Using Organic Rankine Cycle at Covanta’s Haverhill Facility

18th Annual North American Waste-to-Energy Conference ◽

10.1115/nawtec18-3563 ◽

2010 ◽

Author(s):

Heping Cui ◽

Jim Lynch ◽

David McQuillan ◽

Joseph Becker ◽

Tim Sundel

Keyword(s):

Energy Efficiency ◽

Power Output ◽

Energy Recovery ◽

Landfill Gas ◽

Organic Rankine Cycle ◽

Rankine Cycle ◽

Low Grade ◽

Waste Energy ◽

City Water ◽

Net Power Output

Covanta Energy, in cooperation with United Technologies Corporation (UTC), has evaluated, designed, and is in the process of installing an Organic Rankine Cycle (ORC) system at its Haverhill Energy from Waste (EfW) Facility to improve heat recovery and energy efficiency, and to generate more clean renewable energy. ORC systems have been applied in geothermal applications and some other industrial processes to recover low grade and waste energy to generate electricity. This paper describes the design and integration of the ORC system into the Haverhill EfW steam cycle, and the landfill gas engine system, which also operates at the facility. The anticipated energy efficiency improvements and increased net power output have been analyzed and simulated. The results show that the integration of the ORC system could lead to a potential increase in the net power output by as much as 305 kWe in the summer and by 210 kWe in normal weather. It is also anticipated that with the ORC system the facility has the potential to improve the overall plant energy efficiency, as well as save city water.

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Energy Conversion Using the Supercritical Steam Cycle

Advanced Applications of Supercritical Fluids in Energy Systems - Advances in Chemical and Materials Engineering ◽

10.4018/978-1-5225-2047-4.ch014 ◽

2017 ◽

pp. 458-480

Author(s):

Thomas Schulenberg

Keyword(s):

Power Plant ◽

Electric Power ◽

Power Plants ◽

Large Scale ◽

Nuclear Reactors ◽

Rankine Cycle ◽

Boiler Design ◽

Sliding Pressure ◽

Technical Solutions ◽

Supercritical Water Cooled Reactor

A supercritical steam (or Rankine) cycle is used today for more most of the new coal-fired power plants. More recently, it has been proposed as well for future water-cooled nuclear reactors to enhance their efficiency and to reduce their costs. This chapter provides the technical background explaining this technology. Some criteria for boiler design and operation, like drum or once-through boiler design, fixed or sliding pressure operation and coolant mixing, are discussed in general to explain the particular challenges of supercritical steam cycles. Examples of technical solutions are given for two large-scale applications: a coal-fired power plant and a supercritical water-cooled reactor, both producing around 1000 MW electric power.

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Organic Rankine Cycle as Bottoming Cycle to a Combined Brayton and Clausius - Rankine Cycle

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.597.87 ◽

2013 ◽

Vol 597 ◽

pp. 87-98

Author(s):

Dariusz Mikielewicz ◽

Jan Wajs ◽

Elżbieta Żmuda

Keyword(s):

Power Plant ◽

Power Plants ◽

Large Scale ◽

Organic Rankine Cycle ◽

Rankine Cycle ◽

Combined Cycle ◽

Working Fluid ◽

Preliminary Evaluation ◽

Organic Fluids ◽

Steam Cycle

A preliminary evaluation has been made of a possibility of bottoming of a conventional Brayton cycle cooperating with the CHP power plant with the organic Rankine cycle installation. Such solution contributes to the possibility of annual operation of that power plant, except of operation only in periods when there is a demand for the heat. Additional benefit would be the fact that an optimized backpressure steam cycle has the advantage of a smaller pressure ratio and therefore a less complex turbine design with smaller final diameter. In addition, a lower superheating temperature is required compared to a condensing steam cycle with the same evaporation pressure. Bottoming ORCs have previously been considered by Chacartegui et al. for combined cycle power plants [ Their main conclusion was that challenges are for the development of this technology in medium and large scale power generation are the development of reliable axial vapour turbines for organic fluids. Another study was made by Angelino et al. to improve the performance of steam power stations [. This paper presents an enhanced approach, as it will be considered here that the ORC installation could be extra-heated with the bleed steam, a concept presented by the authors in [. In such way the efficiency of the bottoming cycle can be increased and an amount of electricity generated increases. A thermodynamic analysis and a comparative study of the cycle efficiency for a simplified steam cycle cooperating with ORC cycle will be presented. The most commonly used organic fluids will be considered, namely R245fa, R134a, toluene, and 2 silicone oils (MM and MDM). Working fluid selection and its application area is being discussed based on fluid properties. The thermal efficiency is mainly determined by the temperature level of the heat source and the condenser conditions. The influence of several process parameters such as turbine inlet and condenser temperature, turbine isentropic efficiency, vapour quality and pressure, use of a regenerator (ORC) will be presented. Finally, some general and economic considerations related to the choice between a steam cycle and ORC are discussed.

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Organic Rankine Cycle for Residual Heat to Power Conversion in Natural Gas Compressor Station. Part II: Plant Simulation and Optimisation Study

Archives of Mining Sciences ◽

10.1515/amsc-2016-0019 ◽

2016 ◽

Vol 61 (2) ◽

pp. 259-274

Author(s):

Maciej Chaczykowski

Keyword(s):

Energy Recovery ◽

Large Scale ◽

Organic Rankine Cycle ◽

Thermodynamic Characteristics ◽

Rankine Cycle ◽

Working Fluid ◽

Compressor Station ◽

Gas Temperature ◽

Operational Conditions ◽

Recovery Potential

Abstract After having described the models for the organic Rankine cycle (ORC) equipment in the first part of this paper, this second part provides an example that demonstrates the performance of different ORC systems in the energy recovery application in a gas compressor station. The application shows certain specific characteristics, i.e. relatively large scale of the system, high exhaust gas temperature, low ambient temperature operation, and incorporation of an air-cooled condenser, as an effect of the localization in a compressor station plant. Screening of 17 organic fluids, mostly alkanes, was carried out and resulted in a selection of best performing fluids for each cycle configuration, among which benzene, acetone and heptane showed highest energy recovery potential in supercritical cycles, while benzene, toluene and cyclohexane in subcritical cycles. Calculation results indicate that a maximum of 10.4 MW of shaft power can be obtained from the exhaust gases of a 25 MW compressor driver by the use of benzene as a working fluid in the supercritical cycle with heat recuperation. In relation to the particular transmission system analysed in the study, it appears that the regenerative subcritical cycle with toluene as a working fluid presents the best thermodynamic characteristics, however, require some attention insofar as operational conditions are concerned.

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