Journal of Gas Technology
Volume:2 Issue: 1, Spring 2017

LNG production is an intense and complex process, in which the liquefaction accounts for more than 50% of costs. In recent years, design engineers have been made several attempts to optimize this process. The main objective was to increase the production yield and capacity, and minimize the costs. The most important process equipment in liquefaction stage is devoted to compact heat exchangers of Plate Fin or Spiral Wounded types. This article described the simulation of liquefaction cycle of Iran LNG project with triple mixed refrigerant to provide a new method for designing the plate heat exchanger used in this cycle; in addition, a simple method was introduced for selecting the best secondary surface based on the conceptual development of the volume performance index (VPI). The designed exchanger had the minimum surface area and volume. The reduction of required heat transfer surface area had a significant role in the reduction of investment capital cost in LNG production process. The liquefaction cycle of Iran LNG was fully investigated in this article as an industrial case. According to the simulation, the cold and hot surface areas of the plate heat exchanger, used in the given process, are as large as 3001m2 and 1933m2 with the overall heat transfer coefficient of 425 W/ m2K°; whereas, designing this exchanger by developed rapid design algorithm (RDA) significantly can be reduced the required cold and hot surface areas by 5.2 and 3.3 times, respectively. The overall heat transfer coefficient was also increased by 2 times.

In gas-condensate reservoirs as the bottom hole pressure drops below the hydrocarbon dew point of the reservoir fluid, liquids drop out from the gas phase and establish condensate banking near the wellbore, resulting in lower gas productivity. Changing the reservoir rock wettability from liquid-wetting to gas-wetting has outstanding potential in improving the productivity of gas wells. In this work, we report the highly water- and oil-repellent properties of carbonate reservoir rocks treated with a nanofluid based on synthesized ZnO/SiO2 nanocomposites and fluoro containing materials PTFE, TFE, and PFOS. Carbonate plates coated with the prepared nanofluid exhibits a high contact angle of 162° for brine (contact angle hysteresis=0° and roll-off angle

Asphaltene precipitation in oil reservoirs has been involved with numerous problems. Therefore, it is required to understand the precipitation mechanisms in detail in order to diminish the associated difficulties. There are several ways to detect asphaltene precipitation. One of these methods is vanishing interfacial tension (VIT) method. In this method by plotting the equilibrium interfacial tension (IFT) versus pressure, the asphaltene precipitation conditions can be predicted. In this study, for more accurate evaluation of asphaltene precipitation in oil reservoirs by using IFT versus pressure plots, synthetic oil solutions made up of toluene and normal paraffins are used. Solutions with different compositions of toluene and normal paraffins such as n-decane and n heptane with and without asphaltene (extracted from crude oil) are prepared. Then, the equilibrium IFT of the solutions in the proximity of CO2 at different pressure conditions is measured. By plotting the IFT data versus pressure, the onset of asphaltene precipitation in presence of gas and the impact of different parameters on this phenomenon are investigated. Experimental results show that the presence of asphaltene in synthetic solutions changes the behavior of IFT data with pressure. For a solution of toluene and normal paraffin containing asphaltene, the IFT of the solution in presence of CO2 decreases linearly with two different slopes at low and high pressure ranges. The results confirm that the presence of normal paraffin intensifies asphaltene precipitation. The experimental results show that the higher mass fraction of asphaltene is, the higher would be the intensity of the asphaltene precipitation for the attempted mass fractions.

This study evaluates the effect of Structural modifications on energy consumption of gas treatment units of BIDBOLAND refinery (Iran’s first gas refinery). To this aim, Aspen HYSYS (V.8.3) software was employed for the unit simulation in rate based method. The results show that as CO2 content in inlet sour gas is less than 2 percent and MDEA solution is used as solvent, using multiple feeds to the absorption column, static mixers and absorption column sidestream cannot reduce energy consumption level; while using desorption column sidestream and a flash unit can reduce the unit energy consumption up to 10 percent.

A novel thermally coupled reactor containing steam methane reforming in the endothermic side and chemical looping combustion as an exothermic side has been investigated in this study. In this innovative configuration, huge fired furnace of conventional steam reforming process is substituted by chemical looping combustion in a recuperative coupled reactor. This reactor has three concentric tubes where the steam methane reforming is supposed to occur in the middle tube and the inner and outer tubes are considered to be air and fuel reactors of chemical looping combustion, respectively. Copper is selected as solid oxygen carrier in the chemical looping combustion process. Both oxidation and reduction of Cu in the air and fuel reactor are exothermic and used as heat sources for endothermic steam methane reforming. A steady state heterogeneous model of fixed bed for steam reformer and a moving bed for chemical looping combustion reactor predict the performance of this new configuration. The counter-current mode is investigated and simulation results are compared with corresponding predictions of the conventional steam reformer. The results prove that synthesis gas production is increased in thermally coupled reactor in comparison with conventional steam reformer.

Application of mixed amine solution in gas sweetening unit decreases the operation cost and corrosion rate. Also it increases the amount of sulfur in acid gas stream that exits from sweetening and enters to sulfur recovery units. Gas sweetening unit of Bidboland gas refinery (BGR) was simulated by Hysys software. Simulation of BGR had good agreement with industrial data. The parameters such as CS (carbon dioxide in sweet gas), SSRU (the amount of H2S in outlet acid gas stream from stripper to sulfur recovery unit), RAL (rich amine loading) and HPA (reboiler duty per amine circulation rate), were compared for ten blends of DEA (Diethanolamine) and MDEA (Methyl Diethanolamine). According to technical specified parameters, mixed amine with composition of 40 wt. % MDEA and 10 wt. % DEA identified as a good amine blend for gas sweetening unit in BGR. JOGPT. Because Photonics is produced in DOC, strict adherence to format.