On the Design of an ORC Axial Turbine Based Expander Working As a Mechanical Driver in Gas Compressor Stations

2021 ◽  
Author(s):  
Lisa Branchini ◽  
Cesar Celis ◽  
Sebastian Ruiz ◽  
Rene Aguilar ◽  
Andrea De Pascale ◽  
...  
Keyword(s):  
Natural Gas ◽  
Mechanical Energy ◽  
Three Dimensional ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Medium Size ◽  
Axial Turbine ◽  
Exhaust Heat ◽  
Actual Operation ◽  
Wasted Heat

Abstract In this work, the feasibility of increasing the capacity of a natural gas compressor station by means of an Organic Rankine Cycle (ORC) is studied. In the proposed configuration, the ORC recovers natural gas compressor drivers’ wasted heat and converts it into mechanical energy. Thus, as innovative approach, the ORC generated mechanical power will be used to drag an additional gas compressor. A case study representative of a medium-size on-shore facility is taken as reference. The mechanical drivers’ arrangement is composed of four recuperated GTs of PGT5 R type (three units continuously operating and one used as back-up) and two smaller engines of Solar Saturn 20 type. Assuming the actual operation of the station, the addition of an ORC, as bottomer cycle, is designed to recover the exhaust heat from the three PGT5 R running units. According to the Authors’ preliminary investigations and state of the art MW-size parameters, a regenerative sub-critical ORC cycle is selected. Therminol 66 and Hexamethyldisiloxane (MM) are chosen as intermediate and working fluids, respectively. The design ORC key cycle parameters are identified: about 2700 hp (2 MW) of capacity could be added to drive a compressor. For a comprehensive investigation, ORC off-design operating range is explored too assuming one out of three topper cycle units out of service. Since a direct coupling of the ORC driver and the gas compressor is expected, thus excluding the use of gearboxes to avoid losses, an ORC axial turbine based expander is designed that accommodates variable speed operation. The referred design includes mean-line calculations and three-dimensional computational fluid dynamics (CFD) based numerical simulations at design and off design point conditions.

scholarly journals Organic Rankine Cycle for Residual Heat to Power Conversion in Natural Gas Compressor Station. Part I: Modelling and Optimisation Framework

2016 ◽  
Vol 61 (2) ◽  
pp. 245-258
Author(s):  
Maciej Chaczykowski
Keyword(s):  
Natural Gas ◽  
Gas Turbines ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Design Parameters ◽  
Compressor Station ◽  
Natural Gas Pipeline ◽  
Modelling Framework ◽  
Exhaust Heat ◽  
Waste Energy

Abstract Basic organic Rankine cycle (ORC), and two variants of regenerative ORC have been considered for the recovery of exhaust heat from natural gas compressor station. The modelling framework for ORC systems has been presented and the optimisation of the systems was carried out with turbine power output as the variable to be maximized. The determination of ORC system design parameters was accomplished by means of the genetic algorithm. The study was aimed at estimating the thermodynamic potential of different ORC configurations with several working fluids employed. The first part of this paper describes the ORC equipment models which are employed to build a NLP formulation to tackle design problems representative for waste energy recovery on gas turbines driving natural gas pipeline compressors.

scholarly journals Exergy, Economic, and Life-Cycle Assessment of ORC System for Waste Heat Recovery in a Natural Gas Internal Combustion Engine

Resources ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 2 ◽  
Author(s):  
Guillermo Valencia Ochoa ◽  
Javier Cárdenas Gutierrez ◽  
Jorge Duarte Forero
Keyword(s):  
Life Cycle ◽  
Natural Gas ◽  
Waste Heat ◽  
Combustion Engine ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Working Fluid ◽  
Exergy Destruction ◽  
Tube Heat Exchanger ◽  
Exhaust Heat

In this article, an organic Rankine cycle (ORC) was integrated into a 2-MW natural gas engine to evaluate the possibility of generating electricity by recovering the engine’s exhaust heat. The operational and design variables with the greatest influence on the energy, economic, and environmental performance of the system were analyzed. Likewise, the components with greater exergy destruction were identified through the variety of different operating parameters. From the parametric results, it was found that the evaporation pressure has the greatest influence on the destruction of exergy. The highest fraction of exergy was obtained for the Shell and tube heat exchanger (ITC1) with 38% of the total exergy destruction of the system. It was also determined that the high value of the heat transfer area increases its acquisition costs and the levelized cost of energy (LCOE) of the thermal system. Therefore, these systems must have a turbine technology with an efficiency not exceeding 90% because, from this value, the LCOE of the system surpasses the LCOE of a gas turbine. Lastly, a life cycle analysis (LCA) was developed on the system operating under the selected organic working fluids. It was found that the component with the greatest environmental impact was the turbine, which reached a maximum value of 3013.65 Pts when the material was aluminum. Acetone was used as the organic working fluid.

Optimal Load Allocation of Compressors Drivers Taking Advantage of Organic Rankine Cycle As WHR Solution

2020 ◽  
Author(s):  
Michele Bianchi ◽  
Lisa Branchini ◽  
Andrea De Pascale ◽  
Francesco Melino ◽  
Antonio Peretto ◽  
...  
Keyword(s):  
Natural Gas ◽  
Gas Turbines ◽  
Carbon Tax ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Primary Energy ◽  
Economic Feasibility ◽  
Optimal Distribution ◽  
Wasted Heat

Abstract Natural gas demand is projected to continue growing in the long-run and the gas distribution networks are intended to expand with it. The gas compression, along the pipeline, is usually performed in centrifugal compressors driven by gas turbines. In a typical installation, a significant portion of primary energy introduced with natural gas is discharged into the atmosphere with gas turbine exhaust gases, as wasted heat. Since the important investment of the last years, it is of major interest to study solutions for compressor stations, in order to reduce the primary energy consumption and the operative costs. A promising way to enhance the process efficiency, achieving the aforementioned goals, involves recovering compressors drivers wasted heat and converting it into mechanical or electrical energy through an Organic Rankine Cycle (ORC). In this study, the feasibility of adding additional compressor capacity inside the station, with the help of an ORC, as waste heat recovery technology, is studied. In particular, the Authors propose a procedure to identify the bottomer cycle optimal size and to re-define the optimal distribution of driver’s loads inside the station. The strategy consists in the resolution of a minimum constrained problem, such as the loads are re-allocated between gas turbines and ORC, in order to minimize the fuel consumption of the station. Constraints of the problem are the load balance of the system and the regulation limits of each units. The objectives are: (i) to identify the optimal sizes for ORC and electric motor driven compressor to be installed; (ii) to redefine the optimal distribution of the loads based on an annual operating profile of compressors; (iii) to quantify the environmental savings in terms of CO2 avoided compared to the original set-up of the facility; (iv) to assess the economic feasibility in the presence of additional aspects, as, for example, a carbon tax. A typical interstate gas compressor station, with about 24 MW of mechanical drivers installed is taken as case study. Results of the study show that, for the investigated case study, the optimal ORC size turns out to be close to 5.3 MW, which correspond to an additional compressor power consumption of 4.8 MW that can be provided to the ORC driven compressor. Thus, resulting ORC design allows to produce — via an electric motor generator, connecting the ORC and the user — the 18 % of the yearly station mechanical energy demand. A reduction of 22 % of CO2 emissions, compared to the original arrangement is achieved. The economic feasibility of the proposed solution turns out to be very dependent on the natural gas cost and on the carbon tax, if applied. As expected, higher prices lead to higher avoided costs, thus to higher saving and lower payback periods (4 years), whilst low gas prices and no carbon tax can increase the payback period up to 20 years.

Energy and Exergy Waste Heat Recovery Analysis of a Bulk Carrier Main Diesel Engine Equipped with Dual-Loop Organic Rankine Cycle

2021 ◽  
Author(s):  
Elias A. Yfantis ◽  
Efthymios G. Pariotis ◽  
Theodoros C. Zannis ◽  
Konstantina Asimakopoulou
Keyword(s):  
Diesel Engine ◽  
Energy Analysis ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Ambient Conditions ◽  
Bulk Carrier ◽  
Operational Profile ◽  
Exhaust Heat ◽  
Marine Diesel

The energy and the exergy performance of a dual-loop Organic Rankine Cycle (ORC), which harvests exhaust heat from a two-stroke slow-speed main marine diesel engine of a bulk carrier is examined herein. An energy analysis is adopted to calculate the energy flows to the components of the high-temperature (HT) and the low-temperature (LT) loops of the bottoming ORC and through them, to calculate the energy efficiency of the ORC and the generated power from both expanders. Also, an exergy analysis is implemented to predict the irreversibility rates of the components of both HT and LT loops of the ORC system. Various organic fluids are examined for the HT and the LT ORC loops and the optimum combination is selected based on the results of a parametric analysis. The effect of ambient conditions on the energetic and exergetic performance of the dual-loop ORC is examined. The energy analysis of the bottoming dual-loop ORC is projected to a specific mission operational profile of a bulk carrier for predicting the benefits in fuel cost saving and CO2 and SO2 emission reduction compared to conventional vessel operation.

Numerical Investigation of a Partially Loaded Supersonic ORC Turbine Stage

2020 ◽  
Author(s):  
Karl Ziaja ◽  
Pascal Post ◽  
Marwick Sembritzky ◽  
Andreas Schramm ◽  
Ole Willers ◽  
...  
Keyword(s):  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Water Mixture ◽  
Loss Model ◽  
Sector Model ◽  
Exhaust Heat ◽  
Partial Admission ◽  
Loss Models ◽  
Lower Temperature

Abstract The Organic Rankine Cycle (ORC) represents an emerging technology aimed at exploiting lower temperature heat sources, like waste heat in industrial processes or exhaust heat in combustion engines. One key aspect of this technology is an efficient and economical operation at part load, typically realized by a partial admission control, which is challenging to predict numerically. Full annulus computation can only be avoided applying empirical partial admission loss models to conventional full-admission computations. This article aims at assessing the reliability of such a loss model under real-gas and supersonic conditions as a first step towards knowledge-based improved loss models. Three different operating points of an 18.3 kW ORC turbine working with an ethanol-water mixture with two open stator passages (2 × 36°) are considered. Full annulus CFD computations are compared to experimental data and results of simulations in a conventional, full admission, periodic 72°-sector model with application of a 1D partial admission loss model. The experimentally obtained mass flow rate and efficiency are matched overall within their measurements accuracy. By highest inlet total pressure, the computed efficiency deviates about 4 % from the experiments. Predictions of efficiency based on the full admission and loss model correction deviate from full annulus computations less than 1 %. These findings suggest that the used empirical correlations for partial admission losses can provide acceptable results in the configuration under investigation.

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