Dissertations / Theses on the topic 'Light Naphtha'

碩士<br>國立中正大學<br>化學工程所<br>97<br>The goal of study is to improve the quality of gasoline. The extraction and adsorption are both the ways to produce quality gasoline. The study have two parts: (1) Producing gasohol from aqueous ethanol using gasoline as the solvent ;(2) The desulfurization of the light naphtha. (1) Producing gasohol from aqueous ethanol using gasoline as the solvent: There are two tests in this part: Simulated 3-stage extraction test and the York- Scheibel laboratory continuous extractor test. The goal of these tests is to make the gasohol with extracting the aqueous ethanol containing 90 wt% ethanol ,the following conclusions are: A. The York-Scheibel Extractor is a counter-current LLE containing three theoretical stage without reflux, based on its operation is carried out at room temperature, the mixing stirrer’s rotating speed is 150rpm. B. Reducing the flow rate of the aqueous ethanol can make the low water content of the gasohol. C. Adding 6 wt% MTBE in Reformate gasohol can make the phase separation temperature reduced to-8℃.This is below the required phase separation temperature (-7℃) for 95E3 gasoline. (2) The desulfurization of the light naphtha: The light naphtha have 205ppmw sulfur component. We have two ways to make the low sulfur content. The extraction of the light naphtha test is one stage extraction, which is carried out at1 atm and room temperature. The solvent / the light naphtha ratio are 2. NMP and DMSO are better solvent of our five solvents to extract the sulfur component in the light naphtha with one stage extraction cause it makes less oil loss. The adsorption of the light naphtha test is carried out at an adsorption column under 1 atm and room temperature. The adsorbents are nickel-oxides-entrapped Y-zeolite .The adsorption of the light naphtha can make the sulfur content below 1ppmw. The new desulfurization combine extraction with adsorption can replace the hydrodesulfurization.

The aim of this work is to contribute for the development of adsorption based separation processes with considerable potential for commercial application on the refining industry, namely, in the separation of high research octane number (HRON) paraffins from light naphtha fractions. The development of an adsorption process requires first a detailed knowledge of equilibria and kinetics of adsorption and their impact on the dynamic response of an adsorption column. Accordingly, we start collecting single and mixture adsorption equilibrium isotherms of C6 isomers, n-hexane (nHEX), 3-methylpentane (3MP), 2,3-dimethylbutane (23DMB), and 2,2- dimethylbutane (22DMB), from breakthrough experiments in zeolite beta. This adsorbent was selected because its pore system posses interesting characteristics for the separation of HRON dibranched C6 from their low research octane number (LRON) monobranched isomers. It was found that the sorption hierarchy in zeolite beta was most favourable towards the linear isomer and least favourable towards the dibranched ones. Zeolite beta demonstrated significant selectivity to discriminate between mono and dibranched C6 isomers, especially at low coverage. Based on an analysis of sorption events at the molecular level, a Tri-Site Langmuir model (TSL) was developed to interpret the equilibrium data with good accuracy. Sorption kinetics studied by zero-length chromatography technique allowed us to find the nature of controlling diffusion mechanism; for nHEX and 3MP macropore diffusion is controlling. For 23DMB and 22DMB, the system is governed apparently by both macropore and micropore diffusion. The dynamics of equimolar C5/C6 paraffin fractions in a fixed bed of zeolite beta was studied. Breakthrough experiments demonstrate that the sorption hierarchy is temperature-dependent. At 583 K, an enriched HRON fraction of 22DMB, iso-pentane (iPEN) and 23DMB can be selectively separated from the isomerate feed. For the case of feed mixtures with the typical composition of the hydroisomerization reactor product, the enriched fraction contains LRON n-pentane (nPEN) which decreases the octane quality of the product obtained. However, the use of a layered bed with zeolite 5A and zeolite beta can displace the nPEN from the enriched fraction, resulting in a maximum octane number of about 92.5 points. Aspen Adsim was used to simulate the dynamic behaviour of the C5/C6 fraction in a non-isothermal and non-adiabatic bed giving a good description of the set of experimental data. An optimal design of a mono/dibranched separation process can be achieved by properly tuning the operating temperature and the zeolite 5A/zeolite beta ratio on a layered fixed bed. The performance of a layered pressure swing adsorption (PSA) process for the separation of HRON paraffins from a C5/C6 light naphtha fraction is simulated using a detailed, adiabatic single column PSA model. A zeolite 5A layer is used for selective adsorption of LRON n-paraffins while a zeolite beta layer is used to reduce the concentration of the LRON 3MP in the HRON fraction. The effects of various independent process variables (zeolite 5A-to-zeolite beta ratio, purge-to-feed ratio, cycle time, depressurization mode and operating temperature) on the process performance (product RON, HRON molecules recovery, HRON purity, and process productivity) are evaluated. It is demonstrated that an optimal zeolite 5A-to-zeolite beta ratio can improve the product average RON of up to 1.0 point comparatively to existing processes using zeolite 5A only. Moreover, process simulations demonstrated that an increase of 20 K in the operating temperature results in octane gain of 0.2 RON. The study and development of membrane technologies was also included in this work as an alternative to PSA processes. The preparation of supported zeolite beta membranes was successfully achieved by exploring several combinations of seeding techniques and synthesis methods. The surface of the membranes was completely covered by well intergrown crystals. The quality of the membranes was tested by means of pervaporation of ethanol/1,3,5-triisopropylbenzene mixtures together with permporometry experiments. The performance in the vapour separation of quaternary equimolar mixtures of C6 isomers showed that permeate flux decreases as the branching degree increases following the order: nHEX>>3MP>23DMB>22DMB. In the retentate, the fractions of 3MP and nHEX decrease while the concentration of dibranched isomers is increased compared to the feed composition. The RON of the quaternary mixture was enhanced up to 5 points with the best synthesized membrane. The potential application of the novel metal-organic frameworks (MOFs) as an alternative to zeolites was also addressed. A screening study for mixtures of C6 isomers was performed in three different MOFs.The first is a rigid zirconium terephthalate UiO- 66, which possesses two types of cages of diameter 12 Å and 9 Å; the second is a chromium trimesate MIL-100(Cr), which possesses a rigid structure with giant cages accessible through 5-9 Å microporous windows; and the third is the flexible Zn2 (BDC)2(H2O)2·(DMF) (MOF-2), in which the pore system contains 1-D large channels. Multicomponent equimolar experiments show that UiO-66 exhibits inverse shape selectivity for C6 isomers, being the retention governed by the rotational freedom of the molecules in the small cages. In the MIL-100(Cr), the sorption hierarchy is similar to the one found in zeolite beta. Finally, MOF-2 exhibits extraordinary n/iso selectivity, by making use of an unusual guest-dependent dynamic behaviour to exclusively take up nHEX, while hindering the access of branched C6 isomers to the pore system.<br>Fundação para a Ciência e a Tecnologia e ao Fundo Social Europeu, FEDER

The aim of this work is to contribute for the development of adsorption based separation processes with considerable potential for commercial application on the refining industry, namely, in the separation of high research octane number (HRON) paraffins from light naphtha fractions. The development of an adsorption process requires first a detailed knowledge of equilibria and kinetics of adsorption and their impact on the dynamic response of an adsorption column. Accordingly, we start collecting single and mixture adsorption equilibrium isotherms of C6 isomers, n-hexane (nHEX), 3-methylpentane (3MP), 2,3-dimethylbutane (23DMB), and 2,2- dimethylbutane (22DMB), from breakthrough experiments in zeolite beta. This adsorbent was selected because its pore system posses interesting characteristics for the separation of HRON dibranched C6 from their low research octane number (LRON) monobranched isomers. It was found that the sorption hierarchy in zeolite beta was most favourable towards the linear isomer and least favourable towards the dibranched ones. Zeolite beta demonstrated significant selectivity to discriminate between mono and dibranched C6 isomers, especially at low coverage. Based on an analysis of sorption events at the molecular level, a Tri-Site Langmuir model (TSL) was developed to interpret the equilibrium data with good accuracy. Sorption kinetics studied by zero-length chromatography technique allowed us to find the nature of controlling diffusion mechanism; for nHEX and 3MP macropore diffusion is controlling. For 23DMB and 22DMB, the system is governed apparently by both macropore and micropore diffusion. The dynamics of equimolar C5/C6 paraffin fractions in a fixed bed of zeolite beta was studied. Breakthrough experiments demonstrate that the sorption hierarchy is temperature-dependent. At 583 K, an enriched HRON fraction of 22DMB, iso-pentane (iPEN) and 23DMB can be selectively separated from the isomerate feed. For the case of feed mixtures with the typical composition of the hydroisomerization reactor product, the enriched fraction contains LRON n-pentane (nPEN) which decreases the octane quality of the product obtained. However, the use of a layered bed with zeolite 5A and zeolite beta can displace the nPEN from the enriched fraction, resulting in a maximum octane number of about 92.5 points. Aspen Adsim was used to simulate the dynamic behaviour of the C5/C6 fraction in a non-isothermal and non-adiabatic bed giving a good description of the set of experimental data. An optimal design of a mono/dibranched separation process can be achieved by properly tuning the operating temperature and the zeolite 5A/zeolite beta ratio on a layered fixed bed. The performance of a layered pressure swing adsorption (PSA) process for the separation of HRON paraffins from a C5/C6 light naphtha fraction is simulated using a detailed, adiabatic single column PSA model. A zeolite 5A layer is used for selective adsorption of LRON n-paraffins while a zeolite beta layer is used to reduce the concentration of the LRON 3MP in the HRON fraction. The effects of various independent process variables (zeolite 5A-to-zeolite beta ratio, purge-to-feed ratio, cycle time, depressurization mode and operating temperature) on the process performance (product RON, HRON molecules recovery, HRON purity, and process productivity) are evaluated. It is demonstrated that an optimal zeolite 5A-to-zeolite beta ratio can improve the product average RON of up to 1.0 point comparatively to existing processes using zeolite 5A only. Moreover, process simulations demonstrated that an increase of 20 K in the operating temperature results in octane gain of 0.2 RON. The study and development of membrane technologies was also included in this work as an alternative to PSA processes. The preparation of supported zeolite beta membranes was successfully achieved by exploring several combinations of seeding techniques and synthesis methods. The surface of the membranes was completely covered by well intergrown crystals. The quality of the membranes was tested by means of pervaporation of ethanol/1,3,5-triisopropylbenzene mixtures together with permporometry experiments. The performance in the vapour separation of quaternary equimolar mixtures of C6 isomers showed that permeate flux decreases as the branching degree increases following the order: nHEX>>3MP>23DMB>22DMB. In the retentate, the fractions of 3MP and nHEX decrease while the concentration of dibranched isomers is increased compared to the feed composition. The RON of the quaternary mixture was enhanced up to 5 points with the best synthesized membrane. The potential application of the novel metal-organic frameworks (MOFs) as an alternative to zeolites was also addressed. A screening study for mixtures of C6 isomers was performed in three different MOFs.The first is a rigid zirconium terephthalate UiO- 66, which possesses two types of cages of diameter 12 Å and 9 Å; the second is a chromium trimesate MIL-100(Cr), which possesses a rigid structure with giant cages accessible through 5-9 Å microporous windows; and the third is the flexible Zn2 (BDC)2(H2O)2·(DMF) (MOF-2), in which the pore system contains 1-D large channels. Multicomponent equimolar experiments show that UiO-66 exhibits inverse shape selectivity for C6 isomers, being the retention governed by the rotational freedom of the molecules in the small cages. In the MIL-100(Cr), the sorption hierarchy is similar to the one found in zeolite beta. Finally, MOF-2 exhibits extraordinary n/iso selectivity, by making use of an unusual guest-dependent dynamic behaviour to exclusively take up nHEX, while hindering the access of branched C6 isomers to the pore system.<br>Fundação para a Ciência e a Tecnologia e ao Fundo Social Europeu, FEDER

Gasoline compression ignition (GCI) engines show promise in meeting stringent new environmental regulations, as they are characterized by high efficiency and low emissions. Simulations using chemical kinetic models provide an important platform for investigating the behaviors of the fuels inside these engines. However, because real fuels are complex, simulations require surrogate mixtures of small numbers of species that can replicate the properties of real fuels. Accordingly, the development of high fidelity, well-validated kinetic models for surrogates is critical in order to accurately replicate the combustion chemistry of different fuels under engine-related conditions. This work focuses on the development of combustion kinetic models to better understand gasoline fuel combustion in GCI engines. An updated iso-octane detailed kinetic model was developed based on new thermodynamic group values and recently evaluated rate coefficients from literature. The model was validated against a wide range of experimental data and conditions. The iso-octane model was further used in 0D simulations for a homogeneous charge compression ignition (HCCI) engine. The results showed that the low-temperature heat release in engines increases with engine boosting when the addition of alky radicals to molecular oxygen is more favored. Ethanol addition was also found to act as a radical sink which inhibits the radical pool formation and results in lower reactivity. Although detailed models provide clarification of the combustion chemistry, their high computational cost impedes their utilization in 3-D engine simulations. Hence, a reduced model for toluene primary reference fuels was developed and validated against ignition delay time and flame speed experiments from literature. The model was then used in numerically investigating the effects of the fuel’s physical properties using hollow-cone and multi-hole injectors in a partially premixed compression ignition (PPCI) engine. It was concluded that the effects of physical properties are evident in multi-hole injection cases, which is attributable to the differences in mixture stratification. Finally, reduced models for multi-components surrogates for three full-blend fuels (light naphtha-Haltermann straight-run naphtha and GCI fuels) were developed. The models were validated against ignition delay time experiments from the literature and tested in 3D engine simulations.

碩士<br>國立臺北科技大學<br>車輛工程系碩士班<br>91<br>The study uses blended fuel by adding light naphtha in soybean oil without transesterification. The blended fuel might replace petroleum diesel for increasing the using time limit of petroleum diesel and decreasing vehicle exhaust gas emission and pollution. The experiment proceeded by operating a DI diesel engine of one cylinder. The result of this study indicated the more ratio of light naphtha adding in soybean oil, the more improving in fuel consumption and exhaust gas density value. And although fuel consumption of blended fuel is higher than premium diesel (PD), the less exhaust gas density is emitted. This is because the short period of ignition delay period and the slowly premixed combustion phase. If fuel injection or injection pressure can be adjusted in the future trials, it could be improved more in fuel consumption.

碩士<br>國立臺北科技大學<br>車輛工程系碩士班<br>91<br>In order to reduce the exhaust emission of diesel engines, but not to increase fuel consumption, this research is trying to add ”aliphatic solvents” (i.e. light naphtha) into premium diesel to be an additive of fossil diesel, and we hope that we can decrease the thickness of diesel engines’ exhaust emission and extend the expiration time of fossil diesel fuel. From experiments, we realize that diesel fuel mixed with light naphtha can not only reduce the smoke and NOx thickness of diesel engines’ exhaust emission, but also save fuel consumption. Therefore, ”light naphtha” is a good and practical substitute of fuel. There are still several questions for further realization and research to be the topics in the future. For example: Firstly, the viscosity of light naphtha is very low, we don’t know whether it will affect the elements’ lives of diesel engines’ fuel system or not. Secondly: light naphtha is one kind of high evaporation fuel, and it will make the oil thinner in the crank case to shorter the replacing time of engine lubricants.

碩士<br>國立臺北科技大學<br>車輛工程系所<br>93<br>The blending fuel of cottonseed oil 50% and light naphtha 50% is better than the other blending fuel ratio in BSFC and the concentration of exhaust gas emission under the original DI diesel engine. However, when the fuel injection pressure is changed, the experimental results show the BSFC is decreased, but the concentration of exhaust gas emission is not improved in the lower fuel injection pressure than the original. Moreover, when the fuel injection pressure is higher than the original, the concentration of exhaust gas emission can be improved, but the BSFC is increased a lot. Therefore, it is not a better way to change the injection pressure of the original DI diesel engine.

碩士<br>國立臺北科技大學<br>車輛工程系碩士班<br>92<br>On decreasing the exhaust pollution of the transportation ,it is a hurried task to improve the environmental pollution caused by the concentration of smoke from a Diesel engine with a non-common rail fuel injection pressure system. This study added Light Naphtha into premium diesel as the mixed fuel to replace the premium diesel. It had less fuel consumption, about 2.6% than premium diesel, and besides it can decrease the concentration of smoke and NOx to 21.3% and 2.0%. If we lower the pressure of the fuel injection, it can reduce NOx concentration to the original fuel injection pressure about 0.7%, but it can increase the fuel consumption, smoke and HC concentration about 0.1%, 3.2% and 14.1%, respectively. Oppositely, if we higher the pressure of the fuel injection, it can increase the fuel consumption and NOx concentration to the original fuel injection pressure about 0.2% and 2.0%, but it can decrease the concentration of smoke and HC about 5% and 7.3%, respectively. Therefore, when using mixing fuel , adding light Naphtha into premium diesel , it can choose to hold or raise the pressure of the fuel injection.