The increasing growth of helium consumption in industries and the limited resources of this element are the challenges that industries will face in the future. One way to reduce the energy ...consumption in producing crude helium is to integrate it with low-temperature cycles. Also, using solar energy as a source of energy production in areas that receive adequate solar energy is an important strategy for energy supply in terms of environmental compatibility and sustainable development. In this paper, a novel integrated structure for producing liquid methanol, liquefied natural gas, and crude helium gas using the process of separating helium from natural gas, methanol synthesis process, organic Rankine cycle, and solar dish collectors is developed and analyzed. This hybrid system produces 3590 kmol h
−1
liquid methanol, 3590 kmol h
−1
liquefied natural gas, and 18.91 kmol h
−1
crude helium. The feed gas extracted from the process of separating helium from natural gas is fed to the steam-natural gas reforming unit, which produces syngas with an amount of 16,015 kmol h
−1
. To supply the input heat to the reforming, solar dish collectors with the climatic conditions of Tehran in Iran are used. The produced syngas along with carbon dioxide is fed into the methanol synthesis unit. The energy and exergy efficiencies of the developed integrated structure are 88.48% and 93.79%, respectively. The exergy analysis of the integrated structure shows that the maximum exergy destruction corresponds to the heat exchangers (56.23%) and reactors (13.83%). The sensitivity analysis illustrates that with an increase in the outlet flow temperature of the methanol reactor from 100 to 200 °C, the energy and exergy efficiencies are increased by 9.939% and 9.257%, respectively. Besides, by increasing the amount of carbon dioxide feeding to the methanol production process from 100 to 1200 kmol h
−1
, the net power consumed and its thermal efficiency are increased by 8.489% and 2.855%, respectively.
Nowadays, with increasing energy consumption, global warming, and many problems caused by weather conditions, the tendency to use novel methods of energy generation with high efficiency and low cost ...that reduce environmental pollution has increased. This study investigates the feasibility of using gas pressure energy recovery in natural gas pressure reduction stations by turboexpanders for cogeneration of power and refrigeration. Turboexpanders and compression refrigeration cycles are employed to recover the energy from natural gas pressure reduction stations. Then, natural gas along with the compressed air enters the Brayton power generation cycle and its waste heat is used in the carbon dioxide (CO
2
) power generation plant, multistage Rankine cycle, and multi-effect thermal desalination unit. This integrated structure generates 105.6 MW of power, 2.960 MW of refrigeration, and 34.73 kg s
−1
of freshwater. The electrical efficiencies of the Rankine power generation cycle, CO
2
power generation plant, and the whole integrated structure are 0.4101, 0.4120, and 0.4704, respectively. The exergy efficiency and irreversibility of the developed integrated structure are 60.59% and 68.17 MW, respectively. The exergy analysis of the integrated structure shows that the highest rates of exergy destruction are related to the combustion chamber (59.68%), heat exchangers (14.70%), and compressors (14.46%). The annualized cost of the system (ACS) is used to evaluate the developed hybrid system. The economic analysis of the integrated structure indicated the period of return, the prime cost of the product, and capital cost are 2.565 years, 0.0430 US$ kWh
−1
, and 372.3 MMUS$, respectively. The results reveal that the period of return is highly sensitive to the electricity price, such that the period of return in the developed integrated structure is less than 5 years for the electricity price of 0.092 US$ kWh
−1
and more. Also, the period of return is less than 5 years for the initial investment cost of 632.9 MMUS$ and less, which is economically viable.
Due to limited energy supply sources and environmental issues, the use of renewable energy to replace fossil fuels and reduce pollution has increased. One of the easiest, safest, and most portable ...ways to store renewable energy for a long time is to convert it to liquid methanol. In this paper, a novel integrated system is developed for cogeneration of liquid methanol and freshwater using methane cracking unit integrated with chemical looping combustion, methanol production cycle, multi-effect desalination, and photovoltaic panels. The thermal integration of new structures for cogeneration leads to a reduction in the number of equipment used and an increase in efficiency. This integrated structure produces 23.97 kmol h
−1
liquid methanol, 204.3 kmol h
−1
desalinated water, 42.49 kmol h
−1
solid carbon, 58.52 kmol h
−1
nitrogen, and 668.9 kmol h
−1
hot water. The waste heat of the chemical looping combustion is used to supply methane cracking unit, which produces 84.99 kmol h
−1
hydrogen, 7.582 kmol h
−1
carbon dioxide, and 24.74 kW power. These products and the excess carbon dioxide supplied from outside are used as input feed for the liquid methanol production cycle. Waste heat from the liquid methanol production cycle is used to supply heat to the thermal desalination cycle and produce hot water. The thermal energy and exergy efficiencies of the integrated structure are 48.64% and 71.68%, respectively. In the hybrid structure, the largest share of exergy destruction belongs to reactors (65.61%), photovoltaic panels (17.73%), and heat exchangers (10.97%), respectively. Sensitivity analysis in different operating conditions is used to investigate the sensitivity and changes in the output and important parameters of the process.
Today, the use of a variety of energy with the approach of maximizing the efficiency of energy systems is inevitable regarding the increasing trend of energy demand in the world. Process integration ...reduces the number of equipment required and energy consumption. In this paper, an integrated structure is developed that includes a solid oxide fuel cell (SOFC), a Stirling engine, an organic Rankine cycle (ORC), and a multi-effect distillation using biomass gasification. This integrated structure produces 3103 kW net power, 2.773 kg s
−1
desalinated water, and 3.908 kg s
−1
hot water by receiving 1000 kg h
−1
of biomass. Total electrical and total exergy efficiencies of the integrated system were obtained as 62.88% and 51.56%, respectively. The SOFC and ORC cycles energy efficiencies obtained 53.19 and 22.29%, respectively. The SOFC unit and ORC system exergy efficiencies were calculated by 58.09% and 50.77%, respectively. The largest contribution of the exergy destruction rate occurs in the solid oxide fuel cell and the heat exchangers, accounting for 37.31% and 30.43%. In the performed parametric analysis, the effect of moisture content of gasifier input fuel on the performance of the system was evaluated. One of the most important results is the increase of the total electrical efficiency of the system to 70.81% in case of the increase of moisture to 40 vol%. The maximum amount of net generated power and SOFC generated power occur at 25 vol% moisture content of gasifier input fuel.
Graphic abstract
This study is focused on presenting a novel approach for the cogeneration of liquid carbon dioxide (LCO
2
) and liquefied natural gas (LNG). The main idea of this development is to use air for ...storing and producing energy, meanwhile, transferring cold energy for the liquefaction process of natural gas. Therefore, a mixed refrigeration cycle and liquid air cold energy recovery are considered to liquify natural gas. A carbon dioxide liquefaction cycle and a combined cooling and power cycle are also integrated to increase the output performance of the system by taking advantage of carbon dioxide liquefaction and power production. The power production sub-cycle is assisted with solar parabolic trough collectors, which are placed in the city of Bandar-Abbas, Iran. The obtained results demonstrate that the developed system supplies liquefied natural gas and liquid carbon dioxide at 3600.4 and 1188.2 kg h
−1
, respectively. The exergy calculation displays that the heat exchanges (45.14%), compressors (17.24%), and collectors (14.03%) have the most share of exergy destruction compared to other compounds. The exergy efficiency and irreversibility of the proposed integrated system achieve a 48.91% and 1175 kW, respectively. The sensitivity investigation indicates that the specific energy decreases to 813.6 kJ kg
−1
-LNG and exergy efficiency increases up to 48.91% when the pressure in liquid air increases from 20 to 60 bar. The specific energy and exergy efficiency decrease to 799.9 kJ kg
−1
-LNG and 47.76%, respectively with the increase in outlet temperature of the solar collector exchanger from 155 to 175 °C.
Solar thermochemical reactors have been considered in recent studies because of converting the solar energy to a fuel, which is called solar fuel. In such reactors, heat transfer is a dominant ...phenomenon in generating products. Providing the optimum thermal energy for the solar thermochemical cycle can be gained by adjusting the size of the solar concentrator. In this study, the sizing of the solar concentrator is studied and the best size of the cavity is calculated by the Monte Carlo method. In this reactor using solar energy, the intermediate metal is converted to solar fuel. ZnO/Zn is considered to be the intermediate metal for the reaction. Next, the solar reactor is modeled in three dimensions and all types of heat transfer mechanisms, i.e., conduction, convection, and radiation along with chemical reaction conditions, are also considered. Sensitivity analysis is done based on the solar concentrator size and the aperture cavity. The results show that the optimum size of the dish collector is 5.168 m and the aperture cavity diameter was gained 5 cm for 10 kW
th
solar reactor. Nanofluid is used as cooling fluid, with the best modeled fluid flow rate for this structure, the ratio of annual fluid flow to nanofluid being 1. By examining the hydrogen production reactor, the amount of hydrogen produced in the system is 34 mol m
−3
. Also, the irradiation distribution of the cavity receiver and the temperature distribution of the solar reactor were modeled and analyzed.
The natural gas entering the liquefaction cycle usually consists of nitrogen, ethane, propane and also heavier hydrocarbons which are economically explainable to be separated from methane, ...considering that their heating values are higher than methane. In this paper, a hybrid system is developed and analyzed for liquefied natural gas, natural gas liquids and power tri-generation using LNG/NGLs recovery system, absorption–compression combined refrigeration, organic Rankine cycle and solar parabolic trough collectors. This integrated structure produces 54.12 kg s
−1
NGLs, 66.52 kg s
−1
LNG and 278.5 MW net power output. Specific power consumption, thermal and exergy efficiencies of the hybrid system are 0.3771 kWh kg
−1
LNG, 78.38% and 84.47%, respectively. The pinch method is used to extract the heat exchanger network related to the multi-stream heat exchanger of the hybrid system. To simulate the integrated structure, MATLAB programming, HYSYS and TRNSYS software with the weather conditions of Bandar Abbas city in Iran are used. The effect of natural gas composition entering the cycle on system parameters is studied and reported. Results show that with the reduction in methane percentage in natural gas to 55 mol%, specific power consumption increases to 0.6004 kWh kg
−1
LNG, and thermal efficiency decreases to 71.61%. The integrated structural behavior at different operating conditions is used to investigate the sensitivity analysis.
Graphic abstract
Combined pinch and exergy analysis is herein employed to design and optimize a complex integrated structure of cryogenic natural gas plant based on the dual mixed refrigerant refrigeration cycle. ...Exergy composite curves are applied to reveal possible process improvement. Process intensification can reduce the number of required equipment as well as energy consumption. This integrated structure has specific power of 0.339 (kWh/kg LNG) and exergy efficiency of 66.14%. Sensitivity analysis is used to identify the important parameters affecting on the integrated processes and study behavior of the integrated structure against plant disturbances as well. After identifying important parameters, two single-objective and a NSGAII two-objective genetic algorithms are used to minimize thermodynamic properties and economic values of the integrated structure, simultaneously. Optimization procedure is conducted by structural and operational methods. The amounts of specific power and period of return are decreased by 6.68% and 5.65% by implementing the NSGAII two-objective genetic algorithm.
•Developing of a new structure by optimizing of the process via CPEA method.•Conducting exergy, economic and sensitivity analyses for the integrated structure.•Implementing operational optimizations by NSGA-II evolutionary algorithm.
The significant potential of using wind energy, accessible energy of solar irradiation in large areas of Iran, and global warming challenges are the motivations to develop a solar-wind energy-based ...system for
CO
2
capturing. The innovative proposed system includes a chemical absorption-based process to capture
CO
2
from flue gas. The captured
CO
2
is liquefied by a solar absorption refrigeration process. The excessive heat of the exothermic chemical reactions provides the required heat of a Kalina cycle. The Kalina power cycle and a wind turbine rotor supply the required power of the
CO
2
removal system. Furthermore, parabolic trough collectors are also employed to provide the required heat of the refrigeration and separation systems. Ingoing mass and energy streams of the overall hybrid system are
50009
k
mole
h
-
1
flue gas and solar energy. Moreover, the outgoing stream is
4192
k
mole
h
-
1
liquid
CO
2
. The system is simulated aiming at Aspen HYSYS simulator and energy-exergy analyzed. The overall exergy efficiency of the system is 34.09%, and more than 78.87% of exergy is destroyed in re-boiler and towers by 43.32% and 35.55%, respectively. According to sensitivity analysis, local time, temperature and mass flow of lean amine, number of stripper trays, and the mass flow of flue gas affect optical efficiency of collectors, exergy destruction and efficiency rates of equipment, the energy consumption of the system, production rate of liquid
CO
2
and the number of parabolic trough collectors. Furthermore, the optimum altitude of the wind turbine installation is
50
m
. The required energy of the developed system is supplied by the sun and waste heat energy of the flue gas. Therefore, it is a zero energy system that captures
CO
2
and mitigates the harmful effects of global warming.
This paper investigates operational modification of 250 MW Rajaee natural gas fired electrical power plant by supplying a portion of the required heat load from the solar energy source. The base case ...and the introduced hybrid system, both are simulated in Thermoflow and MATLAB softwares. Simulation of parabolic collector solar field in both methods of power boosting and fuel saving is performed by MATLAB. An economic analysis is done and optimal solar contribution is calculated. The obtained results specify that in solar aided electrical power generation mode can reach higher thermal efficiency in comparison with the using natural gas as fuel. In this case, with utilizing the solar field (120,000 m2) the thermal efficiency extends from 37.0% to 39.1%. The electrical power generation by employing 7.00% of solar heat energy, up to 24.0 MW can be improved. In the fuel saving mode, the gross annual cutbacks of the fuel consumption and CO2 emissions rates for a 12×104 m2 solar collector receiver are 35,125×103 kg and 11,164×103 kg; respectively. The electrical power generation costs and fuel consumption rate saving are 80.0 US$/kWh. Also, period of return for the electrical power generation mode is six years.
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