فهرست مطالب

Gas Processing Journal - Volume:9 Issue: 1, Spring 2021

Gas Processing Journal
Volume:9 Issue: 1, Spring 2021

  • تاریخ انتشار: 1399/12/18
  • تعداد عناوین: 6
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  • Seyed Morteza Mousavi, Kamran Lari, Gholamreza Salehi *, Masoud Torabi Azad Pages 1-10
    Regarding the increased energy consumption of the processes at the operational units in the National Iranian Oil Company, the present study analyzed energy consumption at one of the gas refineries. In this refinery, which is the main supplier of Fajr Jam refinery for the national gas network, as well as an injection into the oil fields of the Iranian South oil company, the pressure of gas after passing through a Joule Thomson valvefrom120 to 70 barg reduced. This pressure drop results in the loss of gas temperature, as a result, temperature decrease to -15 °c. Due to the sudden drop in gas pressure, considerable energy, it will be lost. Replacing the Joule Thomson valve with an expansion turbine to use its recoverable energy was also studied. Based on the results from HYSYS software as well as the refinery’s operational conditions, three solutions were discussed. These solutions include (1) using an expansion turbine for power generation, (2) using an expansion turbine to generate electricity and gas condensates, and (3) using an expansion turbine to produce condensates. Based on the technical and economic analysis of the solutions, as well as the results from environmental flow diagram (EFD), which is designed to compare the rates and the sources of the environmental pollutants, the second solution with an internal rate of return (IRR) of 74.53% and a payback period (PBP) of 1.3 years is regarded as the most suitable scenario. Results from EFD indicate that using the second scenario will decrease CO, CO2, and NOX by 57% in this refinery.
    Keywords: Flare Gas, Expansion Turbine, economy, Simulation, Environmental Flow Diagram
  • Hamed Rezaie Azizabadi *, Masoud Ziabasharhagh, Mostafa Mafi Pages 11-28
    Liquid hydrogen will likely play a significant role in the future of energy as its applications are growing fast. Due to the low efficiency of the existing liquefaction plants, many studies are dedicated to the liquefaction processes. The accuracy of the simulations crucially depends on the fluid package and prediction of thermodynamic properties. Four common equations of state implemented in Aspen HYSYS used for hydrogen liquefaction, including PR, MBWR, SRK, and BWRS, are investigated to find their accuracy for estimating volumetric and calorimetric properties, that are essential for precise simulation of hydrogen liquefaction processes. Results show that MBWR is the best choice for hydrogen liquefaction processes, which are simulated by Aspen HYSYS. MBWR predicts thermodynamic properties of hydrogen and parahydrogen very well, in the whole range of temperature and pressure typically met in the liquefaction processes. The MBWR performs well in predicting enthalpy of ortho-para conversion too. Although PR performs better than SRK and BWRS, none of them yields reliable data in low temperatures, so they could not be applied for liquefaction processes. However, they may lead to desirable results for processes that experience higher temperatures range. An innovative, simplified hydrogen liquefaction cycle is developed to be able to capture the mere effect of EOS on essential performance parameters of the liquefaction cycles such as SEC and COP. Applying PR and MBWR to the developed cycle shows that PR compared to MBWR leads to 10% and 4% deviation in SEC and COP, respectively.
    Keywords: Equation of state, REFPROP, Hydrogen Liquefaction, Modified- Benedict–Webb–Rubin, Aspen HYSYS
  • Mohammad Rahimi *, Homayun Alibabaee Pages 29-42
    This paper presents a combined thermodynamic, economic, and environmental comparison of different configurations for co-production of power and desalinated water. Each configuration is analyzed both with inlet air cooling and without inlet air cooling. The most eminent characteristics for the comparison are cost of produced power, cost of produced water, total annual profit, CO2 emission, and CHP efficiency. The common portions of all configurations are the gas turbine and the desalination system. The primary distinctions between scenarios are arrangement and type of system components. Thermodynamic simulation determines mass flow rate of high pressure and low pressure steam, as well as net power and water production of each configuration. Economic simulation reveals the price of produced power, the price of produced water and the total annual profit of the plant. Also, Environmental analysis specifies the total CO2 emission per annum. Final results show that the third configuration, in which a double-pressure HRSG is utilized, has the lowest CO2 emission per MWh of produced electricity. Also, it is concluded that the second configuration, in which a single-pressure HRSG is utilized, has the lowest specific fuel consumption and consequently the highest CHP efficiency. Sensitivity analysis shows that increasing the inlet air temperature will increase the specific CO2 emission in the second configuration. On the other hand, inlet air temperature increase has a marginal impact on CO2 emission in the first and the third configurations. The economic analysis shows that the first scenario with inlet air cooling has the highest total annual profit.
    Keywords: Thermodynamic, economic comparison, Environmental analysis, Desalination, Power, water cost, Net annual profit
  • Saman Faramarzi, Seyed Mojtaba Mousavi Nainiyan *, Mostafa Mafi, Ramin Ghasemiasl Pages 43-50

    Power plants have problems  supplying fuel in the cold season due to the high domestic demand for natural gas. Therefore, they use alternative fuels such as diesel and fuel oil, which reduce the plant's efficiency and cause environmental problems. Fuel peak-shaving is a solution that means liquefaction and storage of natural gas in hot seasons and then using it in cold seasons. Two cycles of the PRICO and LIMUM3 liquefaction methods, which are the two most peak-shaving cycles in natural gas liquefaction, have been studied and optimized for the case study Shahid Rajaee power plant in Qazvin city, Iran. By performing energy, exergy, and economy analyses, these two cycles are compared. A genetic algorithm is used to optimize and find the appropriate values of the key parameters. Using optimization, the SEC value in PRICO and LIMUM3 cycles experienced +0.15 and +0.12 improvement, respectively. PRICO with SEC value of 0.268 performed better than the other cycle with a value of 0.317. The annual capital expenditure (CAPEX) of the PRICO cycle was 9.12 million $, which is higher than the other cycle by 7.58 million $. The annual cost of operation (OPEX) is saved in the PRICO cycle due to the lower SEC and power consumption. The annual total cost of PRICO is 23.81 million $, which is 6.1% less than that of the LIMUM3 cycle. Finally, by comparing the results, the PRICO cycle was found to be more suitable than LIMUM3 for the peak-shaving of the Shahid Rajaee power plant.

    Keywords: LNG, Mixed Refrigerant, Peak-shaving, Economy Analysis, Exergy Analysis
  • Maryam Ghaderi Ardakani, Jafar Javanmardi *, Payam Parvasi Pages 44-50

    Gas hydrates are ice-like crystalline compounds that are commonly formed in pipelines. Gas hydrate formation blockspipelines and damages equipment. One of the efficient prevention and control methods is using dual-functional inhibitors. Recently ionic liquids have been introduced as dual-functional hydrate inhibitors. Methane hydrate formation kinetics were investigated in the presence of ionic liquids and PVCap.Besides, induction time was calculated in presence of various concentrations of different ionic liquids. For this purpose, the van der Waals-Platteeuw theory, the Peng-Robinson equation of state, and the NRTL activity model were used to describe the chemical potential of the hydrate phase, to elaborate on methane fugacity in the vapor phase, and to predictwater activity in theliquid phase respectively. The results were compared with experimental data and a good agreement between correlated and experimental data was observed.

    Keywords: Gas hydrates, Ionic liquids, Kinetic modeling, Induction time
  • Bahram Jafari*, Mahdi Seddiq, Seyyed Mostafa Mirsalim Pages 73-90

    This numerical research mainly aimed to investigate the impacts of diesel fuel direct injection timing on the combustion characteristics, emission formation, and performance in a high-speed diesel-gasoline Reactivity Controlled Compression Ignition (RCCI) engine under low, medium, and high load operating conditions. The numerical achievements indicated that by late diesel injection timing (32 Crank Angle (CA) Before Top Dead Center (BTDC)), regions with a higher temperature and equivalence ratio were formed in the combustion chamber and caused a simultaneous increase in both Nitrogen Oxides (NOx) and soot emissions. On the contrary, early Diesel Injection Timing (DIT) under low load conditions concurrently reduced NOx and soot due to appropriate air-fuel ratio, more homogeneous airfuel mixture formation as a result of longer Ignition Delay (ID) period, and the absence of high-temperature regions inside the combustion chamber. Also, when DIT was postponed under high load conditions, the combustion process became unstable and noise emission, as well as detonation tendency (sudden auto-ignition), were dramatically increased due to a considerable increase in in-cylinder maximum temperature and pressure rise rate. Furthermore, under low load conditions, because of low flame temperature and its incompetent propagation in the engine cylinder, a substantial amount of unburnt mixture (gasoline) was formed and accumulated at the center of the combustion chamber.

    Keywords: Diesel-gasoline combustion simulation, High-speed diesel engine, RCCI, Dieselinjection timing, Emission, Thermal efficiency