Process Simulations of the Cold Recovery Unit in a LNG CCHP System with Different Power Cycles

2011 ◽  
Vol 90-93 ◽  
pp. 3026-3032
Author(s):  
Heng Sun ◽  
Hong Mei Zhu ◽  
Hong Wei Liu
Keyword(s):  
Energy Efficiency ◽  
High Efficiency ◽  
Rankine Cycle ◽  
Primary Energy ◽  
Combined Cycle ◽  
Power Cycles ◽  
Power Cycle ◽  
Recovery Unit ◽  
Cold Energy ◽  
Cooling Media

A CCHP system using LNG as the primary energy should integrate cold recovery unit to increase the total energy efficiency. A scheme of CCHP consisting of gas turbine-steam turbine combined cycle, absorption refrigeration unit, cold recovery unit and cooling media system is a system with high efficiency and operation flexibility. Three different power cycles using the cold energy of LNG is(are 或 were) presented and simulated. The results show that the cascade Rankine power cycle using ethylene and propane in the two cycles respectively has highest energy efficiency. However, the unit is most complex. The efficiency of ethylene Rankine power cycle is little lower than the cascade one, and is much higher than the traditional propane Rankine cycle. The complexity of ethylene cycle is identical to that of the propane cycle. The ethylene Rankine power cycle is the referred method of cold recovery in a CCHP system based on overall considerations.

A LNG Driven CCHP System with a Cold Energy Recovery Device

2011 ◽  
Vol 71-78 ◽  
pp. 1769-1775
Author(s):  
Heng Sun ◽  
Hong Mei Zhu ◽  
Dan Shu
Keyword(s):  
Rankine Cycle ◽  
High Energy ◽  
Primary Energy ◽  
Industrial Applications ◽  
Combined Cycle ◽  
Utilization Efficiency ◽  
Absorption Refrigeration ◽  
Cold Energy ◽  
Very High Energy ◽  
Very High

The CCHP system based on energy cascade utilization can get very high energy overall utilization efficiency. When LNG is used as the primary energy of a CCHP system, the higher efficiency can be obtained if the cold energy of LNG is recovered. Three CCHP systems integrated with LNG cold recovery facility are presented which are suitable for different situations. The thermodynamic calculation and analysis of the system consisting of combined cycle generating electricity, the LiBr absorption refrigeration units, the cryogenic Rankine cycle generation system and the cooling medium system were carried out. The results showed that the energy utility efficiency of the electricity generating was 34.78% and the total energy utility efficiency was up to 86.49%. This indicates that this technology have the potential to be employed in the industrial applications.

Thermodynamic Analysis and Multi-Objective Optimizations of a Combined Recompression sCO2 Brayton Cycle: tCO2 Rankine Cycles for Waste Heat Recovery

2018 ◽  
Author(s):  
Ali S. Alsagri ◽  
Andrew Chiasson ◽  
Ahmad Aljabr
Keyword(s):  
Carbon Dioxide ◽  
Thermodynamic Analysis ◽  
Thermal Efficiency ◽  
High Efficiency ◽  
Waste Heat ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Brayton Cycle ◽  
Power Cycle ◽  
Exhaust Temperature

A thermodynamic analysis and optimization of a newly-conceived combined power cycle were conducted in this paper for the purpose of improving overall thermal efficiency of power cycles by attempting to minimize thermodynamic irreversibilities and waste heat as a consequence of the Second Law. The power cycle concept comprises a topping advanced recompression supercritical carbon dioxide (sCO2) Brayton cycle and a bottoming transcritical carbon dioxide (tCO2) Rankine cycle. The bottoming cycle configurations included a simple tCO2 Rankine cycle and a split tCO2 Rankine cycle. The topping sCO2 recompression Brayton cycle used a combustion chamber as a heat source, and waste heat from a topping cycle was recovered by the tCO2 Rankine cycle due to an added high efficiency recuperator for generating electricity. The combined cycle configurations were thermodynamically modeled and optimized using an Engineering Equation Solver (EES) software. Simple bottoming tCO2 Rankine cycle cannot fully recover the waste heat due to the high exhaust temperature from the top cycle, and therefore an advance split tCO2 Rankine cycle was employed in order to recover most of the waste heat. Results show that the highest thermal efficiency was obtained with recompression sCO2 Brayton cycle – split flow tCO2 Rankine cycle. Also, the results show that the combined CO2 cycles is a promising technology compared to conventional cycles.

A Combined Power Cycle Using Refuse Incineration and LNG Cold Energy With Use of Regasified LNG

2009 ◽  
Author(s):  
Hamid Mahdavi ◽  
Mosa Meratizaman ◽  
S. Ali Jazayeri
Keyword(s):  
Power Generation ◽  
Parametric Analysis ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Power Cycle ◽  
Energy Cycle ◽  
Cold Energy ◽  
Generation Cycle ◽  
Power Generation Cycle ◽  
Refuse Incineration

The objectives of this paper are to develop a combined power generation cycle using refuse incineration and LNG cold energy, and to conduct parametric analysis to investigate the effects of key parameters on the thermal and exergy efficiencies. The combined cycle consists of an ammonia–water Rankine cycle with refuse incinerator and a LNG cold energy cycle with use of regasified LNG as the extra fuel in the incinerator. The combined cycle is compared with the conventional steam Rankine cycle.

Exergy Analysis of Cascade Ethylene-Propane Rankine Cycle with Cold Energy Recovery of LNG

2012 ◽  
Vol 170-173 ◽  
pp. 2489-2493 ◽  
Author(s):  
Hong Mei Zhu ◽  
Hong Wei Liu ◽  
Heng Sun
Keyword(s):  
Low Temperature ◽  
Exergy Analysis ◽  
Rankine Cycle ◽  
High Energy ◽  
Primary Energy ◽  
Exergy Loss ◽  
Operating Pressure ◽  
Power Cycle ◽  
Cold Energy ◽  
Exergy Losses

Cascade Rankine power cycle is suitable for cold recovery in a CCHP system which uses LNG as the primary energy. It has the advantages of low operating pressure and high energy efficiency. Exergy analysis of a typical cascade ethylene-propane Rankine power cycle is conducted. The results show that the exergy losses mainly occur in the low temperature part of the cycle. The exergy loss in the LNG-ethylene heat exchanger could reach about 46% of the total exergy loss. Therefore, the reduction of the exergy losses in the low temperature is important for the improvement of the performance of cascade power cycle.

scholarly journals Thermodynamic Analysis and Multi-Objective Optimizations of a Combined Recompression SCO2 Brayton Cycle-TCO2 Rankine Cycles for Waste Heat Recovery

2018 ◽  
Author(s):  
Ali S. Alsagri ◽  
Andrew D. Chiasson
Keyword(s):  
Carbon Dioxide ◽  
Thermodynamic Analysis ◽  
Thermal Efficiency ◽  
High Efficiency ◽  
Waste Heat ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Brayton Cycle ◽  
Power Cycle ◽  
Exhaust Temperature

A thermodynamic analysis and optimization of a newly-conceived combined power cycle were conducted in this paper for the purpose of improving overall thermal efficiency of power cycles by attempting to minimize thermodynamic irreversibilities and waste heat as a consequence of the Second Law. The power cycle concept comprises a topping advanced recompression supercritical carbon dioxide (sCO2) Brayton cycle and a bottoming transcritical carbon dioxide (tCO2) Rankine cycle. The bottoming cycle configurations included a simple tCO2 Rankine cycle and a split tCO2 Rankine cycle. The topping sCO2 recompression Brayton cycle used a combustion chamber as a heat source, and waste heat from a topping cycle was recovered by the tCO2 Rankine cycle due to an added high efficiency recuperator for generating electricity. The combined cycle configurations were thermodynamically modeled and optimized using an Engineering Equation Solver (EES) software. Simple bottoming tCO2 Rankine cycle cannot fully recover the waste heat due to the high exhaust temperature from the top cycle, and therefore an advance split tCO2 Rankine cycle was employed in order to recover most of the waste heat. Results show that the highest thermal efficiency was obtained with recompression sCO2 Brayton cycle – split flow tCO2 Rankine cycle. Also, the results show that the combined CO2 cycles is a promising technology compared to conventional cycles.

Parameters Analysis of a Cascade Ethylene-Propane Rankine Cycle with Cold Energy Recovery of LNG

2012 ◽  
Vol 446-449 ◽  
pp. 2895-2899
Author(s):  
Hong Mei Zhu ◽  
Heng Sun ◽  
Hong Wei Liu
Keyword(s):  
High Pressure ◽  
Energy Recovery ◽  
Rankine Cycle ◽  
Primary Energy ◽  
Parameter Analysis ◽  
Operating Pressure ◽  
Cascade System ◽  
Power Cycle ◽  
Cold Energy ◽  
Parameters Analysis

A cascade ethylene-propane Rankine power cycle that can recover LNG’s cold energy is represented. It is rather appreciated for a CCHP system which uses LNG as the primary energy due to the relatively low operating pressure of the cascade system. The parameter analysis is done for the key process parameters which mainly affect the performance of the system. The results show that the performance can be improved by decreasing the low pressure of the ethylene cycle and increasing the high pressure of the propane cycle. The optimized parameters can obtain 7.43% more electric power and 2.4% more cooling energy.

Pre-Design Studies of Cycles With Energy, Exergy, Thermoeconomy and ELCA Analysis

2002 ◽  
Author(s):  
Ahmad R. Azimian ◽  
Pernilla L. Olausson ◽  
Mohsen Assadi
Keyword(s):  
Power Plants ◽  
High Efficiency ◽  
Cost Effective ◽  
Combined Cycle ◽  
Design Studies ◽  
Environmental Friendliness ◽  
Power Cycles ◽  
Power Cycle ◽  
Air Turbine ◽  
Power Generation Systems

High efficiency, environmental friendliness, low operation and maintenance (O&M) costs, and lowest possible impact on the surroundings are some requirements of sustainable energy production. In selection of new power generation systems, a number of steps have to be taken into account to meet these requirements. Here the first law analysis has been implemented and investigated followed by a combination of the first and second law analyses (exergy analysis), and thermoeconomics, and finally an Exergetic Life Cycle Assessment (ELCA) is carried out for two different power cycles. The two cycles, investigated here, are a two-pressure level combined cycle, hereafter called (CC), and a Humid Air Turbine or (HAT-cycle). The main goal of this study is to point out the advantages and the difficulties related to the usage of each and every method and their combinations, and to identify the target groups that can gain knowledge and information using these methods. Since the operators of power plants often do not have access to detailed information about component materials, characteristics, etc., of the power cycle, assumptions have to be made when comparing different cycle configuration with each other. This limited type of data and information has also been used here to create a plausible scenario of how different pre-design methods can differ from each other. One major conclusion that has been drawn is that the two cycles investigated here are favorable in different situations and that the results from application of the three methods mentioned above indicate differences in which cycle is the preferable one. However, using a combination of different analysis methods illuminates the plant strengths and limitations during pre-design studies, but conflicting results need to be resolved to obtain the most cost effective and environmentally-friendly power cycle.

Performance Evaluation of a Small Scale High Efficiency Cogeneration System

2006 ◽  
Author(s):  
Mauro Reini
Keyword(s):  
High Efficiency ◽  
Pressure Ratio ◽  
Organic Rankine Cycle ◽  
Thermodynamic Cycle ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Working Fluid ◽  
Small Scale ◽  
Performance Parameters ◽  
Cogeneration System

In recent years, a big effort has been made to improve microturbines thermal efficiency, in order to approach 40%. Two main options may be considered: i) a wide usage of advanced materials for hot ends components, like impeller and recuperator; ii) implementing more complicated thermodynamic cycle, like combined cycle. In the frame of the second option, the paper deals with the hypothesis of bottoming a low pressure ratio, recuperated gas cycle, typically realized in actual microturbines, with an Organic Rankine Cycle (ORC). The object is to evaluate the expected nominal performance parameters of the integrated-combined cycle cogeneration system, taking account of different options for working fluid, vapor pressure and component’s performance parameters. Both options of recuperated and not recuperated bottom cycles are discussed, in relation with ORC working fluid nature and possible stack temperature for microturbine exhaust gases. Finally, some preliminary consideration about the arrangement of the combined cycle unit, and the effects of possible future progress of gas cycle microturbines are presented.

Intercooled Advanced Gas Turbines in Coal Gasification Plants, With Combined or “HAT” Power Cycle

1997 ◽  
Author(s):  
Paolo Chiesa ◽  
Giovanni Lozza
Keyword(s):  
Gas Turbines ◽  
Coal Gasification ◽  
High Efficiency ◽  
Combined Cycle ◽  
Air Separation ◽  
Heavy Duty ◽  
Power Cycle ◽  
Efficiency Assessment ◽  
The One ◽  
Conversion Efficiencies

Due to their high efficiency and flexibility, aeroderivative gas turbines were often considered as a development basis for intercooled engines, thus providing better efficiency and larger power output. Those machines, originally studied for natural gas, are here considered as the power section of gasification plants for coal and heavy fuels. This paper investigates the matching between intercooled gas turbine, in complex cycle configurations including combined and HAT cycles, and coal gasification processes based on entrained-bed gasifiers, with syngas cooling accomplished by steam production or by full water-quench. In this frame, a good level of integration can be found (i.e. re-use of intercooler heat, availability of cool, pressurized air for feeding air separation units, etc.) to enhance overall conversion efficiency and to reduce capital cast. Thermodynamic aspects of the proposed systems are investigated, to provide an efficiency assessment, in comparison with mare conventional IGCC plants based on heavy-duty gas turbines. The results outline that elevated conversion efficiencies can be achieved by moderate-size intercooled gas turbines in combined cycle, while the HAT configuration presents critical development problems. On the basis of a preliminary cost assessment, cost of electricity produced is lower than the one obtained by heavy-duty machines of comparable size.

CCPP Performance Augmentation Using LNG Re-Gasification Cold Energy

2014 ◽  
Author(s):  
Mihir Acharya ◽  
Lalatendu Pattanayak ◽  
Hemant Gajjar ◽  
Frank Elbracht ◽  
Sandeep Asthana
Keyword(s):  
Power Plant ◽  
Gas Turbine ◽  
High Efficiency ◽  
Clean Energy ◽  
Combined Cycle ◽  
Economic Feasibility ◽  
Air Cooling ◽  
Ambient Conditions ◽  
Combined Cycle Power Plant ◽  
Cold Energy

With gas becoming a fuel of choice for clean energy, Liquefied Natural Gas (LNG) is being transported and re-gasification terminals are being set up at several locations. Re-gasification of LNG leads to availability of considerable cold-energy which can be utilized to gain power and efficiency in a Gas Turbine (GT) based Power Plant. With a number of LNG Re-gasification Terminals coming up in India & around the globe, setting up of a high efficiency CCPP adjacent to the terminal considering utilization of the cold energy to augment its performance, and also save energy towards re-gasification of LNG, provides a feasible business opportunity. Thermodynamic analysis and major applications of the LNG re-gasification cold energy in Gas Turbine based power generation cycle, are discussed in this paper. The feasibility of cooling GT inlet air by virtue of the cold energy of Liquefied LNG to increase power output of a Combined Cycle Power Plant (CCPP) for different ambient conditions is analyzed and also the effect on efficiency is discussed. The use of cold energy in condenser cooling water circulating system to improve efficiency of the CCPP is also analyzed. Air cooling capacity and power augmentation for a combined cycle power plant based on the advanced class industrial heavy duty gas turbine are demonstrated as a function of the ambient temperature and humidity. The economic feasibility of utilizing the cold energy is also deliberated.

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