A powerful method is necessary for thermodynamic modeling of wax phase behavior in crude oils,such as the perturbed-chain statistical associating fluid theory（PC-SAFT）.In this work,a new approach based on the wax ap...A powerful method is necessary for thermodynamic modeling of wax phase behavior in crude oils,such as the perturbed-chain statistical associating fluid theory（PC-SAFT）.In this work,a new approach based on the wax appearance temperature of crude oil was proposed to estimate PC-SAFT parameters in thermodynamic modeling of wax precipitation from crude oil.The proposed approach was verified using experimental data obtained in this work and also with those reported in the literature.In order to compare the performance of the PC-SAFT model with previous models,the wax precipitation experimental data were correlated using previous models such as the solid solution model and multi-solid phase model.The results showed that the PC-SAFT model can correlate more accurately the wax precipitation experimental data of crude oil than the previous models,with an absolute average deviation less than 0.4 %.Also,a series of dynamic experiments were carried out to determine the rheological behavior of waxy crude oil in the absence and presence of a flow improver such as ethylene–vinyl acetate copolymer.It was found that the apparent viscosity of waxy crude oil decreased with increasing shear rate.Also,the results showed that the performance of flow improver was dependent on its molecular weight.展开更多
Based on direct absorption spectroscopy(DAS), a portable methane(CH_4) detection device was implemented. The device mainly includes a dual-channel non-dispersive infrared sensor(integrated with an infrared light sourc...Based on direct absorption spectroscopy(DAS), a portable methane(CH_4) detection device was implemented. The device mainly includes a dual-channel non-dispersive infrared sensor(integrated with an infrared light source, light path and pyroelectric detector), a driving circuit of the sensor, an ARM11 embedded Win CE system, and a Lab VIEW-based data-processing platform. Experiments were carried out with prepared CH_4 samples to investigate the sensing performance. The relative detection error is less than 9.14% within the measuring range of 0—7×10^(-2). For a CH_4 sample with concentration of 0(i.e., pure nitrogen), the measured concentration fluctuation range is-1.2×10^(-5)—+2×10^(-5). An Allan deviation analysis on the gas sample with concentration of 0 indicates that the 1σ limit of detection(LoD) of the device is 4.8×10^(-6) with an average time of 1 s. Experiments were performed on three CH_4 samples with different concentrations to test the response time, which is validated to be less than 20 s. Due to the small size of the ARM11 embedded system and the powerful data processing capability of the Lab VIEW platform, the proposed portable and miniaturized CH_4 sensor shows a good application prospect in mining operations and some other industrial fields.展开更多
文摘A powerful method is necessary for thermodynamic modeling of wax phase behavior in crude oils,such as the perturbed-chain statistical associating fluid theory（PC-SAFT）.In this work,a new approach based on the wax appearance temperature of crude oil was proposed to estimate PC-SAFT parameters in thermodynamic modeling of wax precipitation from crude oil.The proposed approach was verified using experimental data obtained in this work and also with those reported in the literature.In order to compare the performance of the PC-SAFT model with previous models,the wax precipitation experimental data were correlated using previous models such as the solid solution model and multi-solid phase model.The results showed that the PC-SAFT model can correlate more accurately the wax precipitation experimental data of crude oil than the previous models,with an absolute average deviation less than 0.4 %.Also,a series of dynamic experiments were carried out to determine the rheological behavior of waxy crude oil in the absence and presence of a flow improver such as ethylene–vinyl acetate copolymer.It was found that the apparent viscosity of waxy crude oil decreased with increasing shear rate.Also,the results showed that the performance of flow improver was dependent on its molecular weight.
基金supported by the National Natural Science Foundation of China(Nos.61627823,61307124 and 11404129)the Science and Technology Department of Jilin Province of China(Nos.20120707 and 20140307014SF)+1 种基金the Changchun Municipal Science and Technology Bureau(No.14KG022)the State Key Laboratory of Integrated Optoelectronics of Jilin University(No.IOSKL2012ZZ12)
文摘Based on direct absorption spectroscopy(DAS), a portable methane(CH_4) detection device was implemented. The device mainly includes a dual-channel non-dispersive infrared sensor(integrated with an infrared light source, light path and pyroelectric detector), a driving circuit of the sensor, an ARM11 embedded Win CE system, and a Lab VIEW-based data-processing platform. Experiments were carried out with prepared CH_4 samples to investigate the sensing performance. The relative detection error is less than 9.14% within the measuring range of 0—7×10^(-2). For a CH_4 sample with concentration of 0(i.e., pure nitrogen), the measured concentration fluctuation range is-1.2×10^(-5)—+2×10^(-5). An Allan deviation analysis on the gas sample with concentration of 0 indicates that the 1σ limit of detection(LoD) of the device is 4.8×10^(-6) with an average time of 1 s. Experiments were performed on three CH_4 samples with different concentrations to test the response time, which is validated to be less than 20 s. Due to the small size of the ARM11 embedded system and the powerful data processing capability of the Lab VIEW platform, the proposed portable and miniaturized CH_4 sensor shows a good application prospect in mining operations and some other industrial fields.
