The Experts below are selected from a list of 202650 Experts worldwide ranked by ideXlab platform

Scott H Fogler - One of the best experts on this subject based on the ideXlab platform.

  • effects of operating conditions on wax deposit Carbon Number distribution theory and experiment
    Energy & Fuels, 2013
    Co-Authors: Sheng Zheng, Fan Zhang, Zhenyu Huang, Scott H Fogler
    Abstract:

    Wax deposition in subsea pipelines is a problem of enormous economic consequences. The Carbon Number distribution (CND) is an important characteristic of the deposit because it significantly affects the yield stress of wax deposit , which is important in the design of the remediation technique of pigging. In this study, the recent theories for wax thermodynamic modeling are coupled with heat and mass transport modeling to identify the critical factors that determine the Carbon Number distribution of wax deposits. It is found that the deposit Carbon Number distribution is closely related to the diffusion of different n-alkane components and their respective concentration driving forces. The impact of molecular diffusion of the multiple components on the evolution of deposit Carbon Number distribution is quantified by evaluating of the mass driving force for each n-paraffin component. In addition, the effects of operating conditions on the deposit Carbon Number distribution are investigated by modeling and ...

  • effects of operating conditions on wax deposit Carbon Number distribution theory and experiment
    Energy & Fuels, 2013
    Co-Authors: Sheng Zheng, Fan Zhang, Zhenyu Huang, Scott H Fogler
    Abstract:

    Wax deposition in subsea pipelines is a problem of enormous economic consequences. The Carbon Number distribution (CND) is an important characteristic of the deposit because it significantly affect...

  • existence of a critical Carbon Number in the aging of a wax oil gel
    Aiche Journal, 2001
    Co-Authors: Probjot Singh, Arm Youyen, Scott H Fogler
    Abstract:

    A fundamental study was carried out to understand the aging (or hardening) of the wax-oil gels formed in the subsea pipelines during the flow of crude oil from offshore wells to shore. The aging process is a counterdiffusion phenomenon where there exists a critical Carbon Number (CCN), and wax molecules with Carbon Numbers greater than the CCN diffuse into the gel matrices and vice versa. Using a careful analysis of Carbon Number distributions of gel deposits, collected from a cold finger after various deposition time intervals, the CCN for the wax-oil system was obtained. A mathematical model, based on a modified version of UNIQUAC model, was developed to predict the CCN for wax-oil systems. The size of the interaction units for n-alkanes in the solid-phase UNIQUAC model was found to be a strong function of the mean Carbon Number in the solid phase.

Kihyun Kim - One of the best experts on this subject based on the ideXlab platform.

  • Re-evaluation of effective Carbon Number (ECN) approach to predict response factors of 'compounds lacking authentic standards or surrogates' (CLASS) by thermal desorption analysis with GC-MS.
    Analytica chimica acta, 2014
    Co-Authors: Jan E Szulejko, Kihyun Kim
    Abstract:

    Abstract In our recent study, we experimentally demonstrated the feasibility of an effective Carbon Number (ECN) approach for the prediction of the response factor (RF) values of ‘compounds lacking authentic standards or surrogates’ (CLASS) using a certified 54-mix containing 38 halogenated analytes as a pseudo-unknown. Although our recent analysis performed well in terms of RF predictive power for a 25-component learning set (for both Q-MS and TOF-MS detection), large physically unrealistic negative ECN and Carbon Number equivalent (CNE) values were noted for TOF-MS detection, e.g., ECN (acetic acid) = −16.96. Hence, to further improve the ECN-based quantitation procedure of CLASS, we re-challenged RF vs. ECN linear regression analysis with additional descriptors (i.e., Cl, Br, C C , and a group ECN offset (Ok)) using the 1-point RF values. With an Ok, all compound classes, e.g., halo-alkanes/-alkenes and aromatics can now be fitted to yield consistently positive set of ECN values for most analytes (e.g., 3 outliers out of 29, Q-MS detection). In this way, we were able to further refine our approach so that the absolute percentage difference (PD) ± standard deviation (SD) between mass detected vs. mass loaded is reduced from 39.0 ± 34.1% (previous work) to 13.1 ± 12.0% (this work) for 29 C1 C4 haloCarbons (Q-MS detector).

  • Experimental validation of an effective Carbon Number-based approach for the gas chromatography-mass spectrometry quantification of 'compounds lacking authentic standards or surrogates'.
    Analytica chimica acta, 2014
    Co-Authors: Yonghyun Kim, Jan E Szulejko, Kihyun Kim, Min-suk Bae, Richard J. C. Brown
    Abstract:

    Abstract For the quantitative analysis of ‘compounds lacking authentic standards or surrogates’ (CLASS) in environmental media, we previously introduced an effective Carbon Number (ECN) approach to develop an empirical equation for the prediction of their response factor (RF). In this research, a series of laboratory experiments were carried out to benchmark the reliability of an ECN approach for sorbent tube/thermal desorption/gas chromatography (GC)/mass spectrometry (MS) applications. First, the ECN values were determined using external calibration data from 25 reference volatile organic compounds (VOCs) using two MS dectectors (quadrupole (Q) and time-of-flight (TOF)). Then, a certified standard mixture of 54 VOCs was analyzed by each system as a simulated unknown sample. The analytical bias, assessed in terms of percentage difference (PD) between the certified and ECN-predicted mass values, averaged 19.2 ± 16.1% (TOF-MS) and 28.2 ± 27.6% (Q-MS). The bias using a more simplified Carbon Number (CN)-based prediction increased considerably, yielding 53.4 ± 53.3% (TOF-MS) and 61.7 ± 81.3% (Q-MS). However, the bias obtained using the ECN-based prediction decreased significantly to yield average PD values of 9.84 ± 7.28% (TOF-MS) and 16.8 ± 8.35% (Q-MS), if the comparison was limited to 26 (out of 54) VOCs with CN ≥ 4 (i.e., 25 aromatics and hexachlorobutadiene).

  • method to predict gas chromatographic response factors for the trace level analysis of volatile organic compounds based on the effective Carbon Number concept
    IEEE Journal of Solid-state Circuits, 2013
    Co-Authors: Jan E Szulejko, Yonghyun Kim, Kihyun Kim
    Abstract:

    A procedure has been developed to estimate GC–MS response factors based on the theory of effective Carbon Number defined as the sum of the Carbon Number and Carbon Number equivalent for each selected molecular descriptor (multiplied by its Number of occurrences) in each compound's molecular structure. As a means to validate the effective Carbon Number procedure for GC–MS analysis, a test suite of 19 volatile organic compounds was analyzed by the sorbent-tube thermal desorption method. In the effective Carbon Number procedure, the Carbon Number equivalent for each descriptor was determined to yield the optimal linear plots between response factor versus the effective Carbon Number with the maximum R2 (>0.975) and the minimum mean absolute error (<5%). Effective Carbon Number analysis is validated as a potent approach to estimate response factor values for most compounds amenable to the sorbent-tube thermal desorption GC–MS method. Overall, it is concluded that the application of response factor versus effective Carbon Number relationship can produce fairly reliable prediction with reduced errors relative to other comparable procedures such as the response factor versus the Carbon Number approach.

  • Method to predict gas chromatographic response factors for the trace-level analysis of volatile organic compounds based on the effective Carbon Number concept.
    Journal of separation science, 2013
    Co-Authors: Jan E Szulejko, Yonghyun Kim, Kihyun Kim
    Abstract:

    A procedure has been developed to estimate GC–MS response factors based on the theory of effective Carbon Number defined as the sum of the Carbon Number and Carbon Number equivalent for each selected molecular descriptor (multiplied by its Number of occurrences) in each compound's molecular structure. As a means to validate the effective Carbon Number procedure for GC–MS analysis, a test suite of 19 volatile organic compounds was analyzed by the sorbent-tube thermal desorption method. In the effective Carbon Number procedure, the Carbon Number equivalent for each descriptor was determined to yield the optimal linear plots between response factor versus the effective Carbon Number with the maximum R2 (>0.975) and the minimum mean absolute error (

Suojiang Zhang - One of the best experts on this subject based on the ideXlab platform.

  • pure Carbon Number components to characterize the hydroCarbon mixture for kinetic modeling of hydrogenation process
    Fuel, 2017
    Co-Authors: Yiqian Yang, Chunshan Li, Zengxi Li, Hongyan Wang, Suojiang Zhang
    Abstract:

    Abstract Hydrogenation is an important processing technology for upgrading inferior oil. Kinetic modeling for hydrogenation process continues to be a challenging task because of the complex compounds and reactions involved. Therefore, a systematic Carbon-Number components-based substitution approach was proposed in this work as representatives of real feedstock (e.g. residual oil, vacuum gas oil, coal tar, etc). The primary advantage of the approach lies in direct availability of chemical character and physical property data. The detailed molecular compositions of components were also determined in the optimization algorithm by correlating the bulk experimental properties of original mixture. On this basis, the detailed kinetic modeling of hydrogenation process based on the real components reaction pathway could be constructed. The approach was verified using a set of 64 pure components to characterize the coal tar feedstock and used to simulate the reaction modeling of coal tar hydrogenation process. Results revealed that the hydrogenation product distribution and the chemical hydrogen consumption were predicted effectively. This work provides a significant guidance for the design and optimization of hydrogenation process.

  • Carbon-Number-Based Kinetics, Reactor Modeling, and Process Simulation for Coal Tar Hydrogenation
    Energy & Fuels, 2015
    Co-Authors: Fei Dai, Maoming Gong, Hongyan Wang, Suojiang Zhang
    Abstract:

    A new Carbon-Number-based kinetic model containing 18 hydroCarbon groups was developed in this work to describe coal tar hydrogenation, and the kinetic parameters were determined by means of fitting the experimental data, obtained in a two-stage fixed-bed reactor hydrogenation experiment, under various operating conditions. Model validation revealed that experimental data considerably agreed with expected outcomes. On this basis, a non-isothermal reactor model based on mass balance and energy balance as well as the proposed reaction kinetic model were constructed to further investigate the behavior of the hydrogenation fixed-bed unit, and the reactor model applied in a bench-scale plant of coal tar hydrogenation accurately simulated and predicted the yield distribution of Carbon Number products and the temperature profile along with the reactor. In addition, the entire process simulation for coal tar hydrogenation was developed using Aspen Plus. The simulation provided a significant guide for the optimiza...

  • new kinetic model of coal tar hydrogenation process via Carbon Number component approach
    Applied Energy, 2015
    Co-Authors: Maoming Gong, Chunshan Li, Zengxi Li, Suojiang Zhang
    Abstract:

    Hydrogenation technology is an important chemical upgrading process for low quality oil such as coal tar. Kinetic modeling for hydrogenation process remains a challenging task because of the large amount of compounds and complex reactions involved. Therefore, a new systematic methodology is proposed in this study to characterize mixture streams for the kinetic modeling of coal tar hydrogenation. The methodology incorporates both lumped method based on boiling point to represent feedstock and a Carbon Number-based component approach in the form of a structural matrix to characterize products at a molecular level. A mathematical transformation model is built for interrelating the bulk properties and molecular composition of products. A detailed kinetic model for coal tar hydrogenation is constructed based on the reaction pathway networks between lumped feedstock and Carbon Number-based molecular product. Detailed molecular compositions of the products are obtained from experiments to provide a basis for estimating the parameters of the kinetic model. The proposed method is verified by experiment results, which are consistent with predicted values.

  • Simulation of heavy-oil thermal cracking process on the basis of Carbon Number-based component approach
    Computer Aided Chemical Engineering, 2005
    Co-Authors: Xiangping Zhang, Suojiang Zhang, Long Yan, Wenbin Dai
    Abstract:

    Simulation of heavy oil thermal cracking process is very important but few researches have been published now. In this paper, a simulation framework based on the Carbon Number-based approach(CNCA) has been established. A systematic division rule is put forward for dividing cracked products into 59 Carbon Number components. Then the cracking reaction network has been structured and the corresponding reaction rate equations have been obtained. The reaction rate constants were fitted with the experimental data. A plug fluid model is used to model the cracking reactor and the simulation procedure for heavy-oil thermal-cracking process has been developed. The calculated results are compared with the plant data.

Jan E Szulejko - One of the best experts on this subject based on the ideXlab platform.

  • Re-evaluation of effective Carbon Number (ECN) approach to predict response factors of 'compounds lacking authentic standards or surrogates' (CLASS) by thermal desorption analysis with GC-MS.
    Analytica chimica acta, 2014
    Co-Authors: Jan E Szulejko, Kihyun Kim
    Abstract:

    Abstract In our recent study, we experimentally demonstrated the feasibility of an effective Carbon Number (ECN) approach for the prediction of the response factor (RF) values of ‘compounds lacking authentic standards or surrogates’ (CLASS) using a certified 54-mix containing 38 halogenated analytes as a pseudo-unknown. Although our recent analysis performed well in terms of RF predictive power for a 25-component learning set (for both Q-MS and TOF-MS detection), large physically unrealistic negative ECN and Carbon Number equivalent (CNE) values were noted for TOF-MS detection, e.g., ECN (acetic acid) = −16.96. Hence, to further improve the ECN-based quantitation procedure of CLASS, we re-challenged RF vs. ECN linear regression analysis with additional descriptors (i.e., Cl, Br, C C , and a group ECN offset (Ok)) using the 1-point RF values. With an Ok, all compound classes, e.g., halo-alkanes/-alkenes and aromatics can now be fitted to yield consistently positive set of ECN values for most analytes (e.g., 3 outliers out of 29, Q-MS detection). In this way, we were able to further refine our approach so that the absolute percentage difference (PD) ± standard deviation (SD) between mass detected vs. mass loaded is reduced from 39.0 ± 34.1% (previous work) to 13.1 ± 12.0% (this work) for 29 C1 C4 haloCarbons (Q-MS detector).

  • Experimental validation of an effective Carbon Number-based approach for the gas chromatography-mass spectrometry quantification of 'compounds lacking authentic standards or surrogates'.
    Analytica chimica acta, 2014
    Co-Authors: Yonghyun Kim, Jan E Szulejko, Kihyun Kim, Min-suk Bae, Richard J. C. Brown
    Abstract:

    Abstract For the quantitative analysis of ‘compounds lacking authentic standards or surrogates’ (CLASS) in environmental media, we previously introduced an effective Carbon Number (ECN) approach to develop an empirical equation for the prediction of their response factor (RF). In this research, a series of laboratory experiments were carried out to benchmark the reliability of an ECN approach for sorbent tube/thermal desorption/gas chromatography (GC)/mass spectrometry (MS) applications. First, the ECN values were determined using external calibration data from 25 reference volatile organic compounds (VOCs) using two MS dectectors (quadrupole (Q) and time-of-flight (TOF)). Then, a certified standard mixture of 54 VOCs was analyzed by each system as a simulated unknown sample. The analytical bias, assessed in terms of percentage difference (PD) between the certified and ECN-predicted mass values, averaged 19.2 ± 16.1% (TOF-MS) and 28.2 ± 27.6% (Q-MS). The bias using a more simplified Carbon Number (CN)-based prediction increased considerably, yielding 53.4 ± 53.3% (TOF-MS) and 61.7 ± 81.3% (Q-MS). However, the bias obtained using the ECN-based prediction decreased significantly to yield average PD values of 9.84 ± 7.28% (TOF-MS) and 16.8 ± 8.35% (Q-MS), if the comparison was limited to 26 (out of 54) VOCs with CN ≥ 4 (i.e., 25 aromatics and hexachlorobutadiene).

  • method to predict gas chromatographic response factors for the trace level analysis of volatile organic compounds based on the effective Carbon Number concept
    IEEE Journal of Solid-state Circuits, 2013
    Co-Authors: Jan E Szulejko, Yonghyun Kim, Kihyun Kim
    Abstract:

    A procedure has been developed to estimate GC–MS response factors based on the theory of effective Carbon Number defined as the sum of the Carbon Number and Carbon Number equivalent for each selected molecular descriptor (multiplied by its Number of occurrences) in each compound's molecular structure. As a means to validate the effective Carbon Number procedure for GC–MS analysis, a test suite of 19 volatile organic compounds was analyzed by the sorbent-tube thermal desorption method. In the effective Carbon Number procedure, the Carbon Number equivalent for each descriptor was determined to yield the optimal linear plots between response factor versus the effective Carbon Number with the maximum R2 (>0.975) and the minimum mean absolute error (<5%). Effective Carbon Number analysis is validated as a potent approach to estimate response factor values for most compounds amenable to the sorbent-tube thermal desorption GC–MS method. Overall, it is concluded that the application of response factor versus effective Carbon Number relationship can produce fairly reliable prediction with reduced errors relative to other comparable procedures such as the response factor versus the Carbon Number approach.

  • Method to predict gas chromatographic response factors for the trace-level analysis of volatile organic compounds based on the effective Carbon Number concept.
    Journal of separation science, 2013
    Co-Authors: Jan E Szulejko, Yonghyun Kim, Kihyun Kim
    Abstract:

    A procedure has been developed to estimate GC–MS response factors based on the theory of effective Carbon Number defined as the sum of the Carbon Number and Carbon Number equivalent for each selected molecular descriptor (multiplied by its Number of occurrences) in each compound's molecular structure. As a means to validate the effective Carbon Number procedure for GC–MS analysis, a test suite of 19 volatile organic compounds was analyzed by the sorbent-tube thermal desorption method. In the effective Carbon Number procedure, the Carbon Number equivalent for each descriptor was determined to yield the optimal linear plots between response factor versus the effective Carbon Number with the maximum R2 (>0.975) and the minimum mean absolute error (

Burtron H. Davis - One of the best experts on this subject based on the ideXlab platform.

  • fischer tropsch synthesis the paraffin to olefin ratio as a function of Carbon Number
    Catalysis Today, 2005
    Co-Authors: Buchang Shi, Burtron H. Davis
    Abstract:

    The Fischer–Tropsch synthesis (FTS) reaction mechanism has been studied by establishing a steady-state operation using a syngas comprised of H2 and CO and then switching to a syngas feed comprised of D2 and Carbon monoxide. The products made during the 24-h period following switching from a hydrogen-containing syngas to a deuterium-containing one are analyzed for deuterium content. The paraffin/olefin (P/O) ratio of the highly deuterated products represent primary FTS products. The data show that the P/O ratio increases much more slowly with Carbon Number than the O/P ratio of the total products exiting the reactor. The data show that diffusion limitations for the olefin products and their subsequent re-incorporation as chain initiators does not make a major impact on the product distribution.

  • Fischer–Tropsch synthesis: The paraffin to olefin ratio as a function of Carbon Number
    Catalysis Today, 2005
    Co-Authors: Buchang Shi, Burtron H. Davis
    Abstract:

    The Fischer–Tropsch synthesis (FTS) reaction mechanism has been studied by establishing a steady-state operation using a syngas comprised of H2 and CO and then switching to a syngas feed comprised of D2 and Carbon monoxide. The products made during the 24-h period following switching from a hydrogen-containing syngas to a deuterium-containing one are analyzed for deuterium content. The paraffin/olefin (P/O) ratio of the highly deuterated products represent primary FTS products. The data show that the P/O ratio increases much more slowly with Carbon Number than the O/P ratio of the total products exiting the reactor. The data show that diffusion limitations for the olefin products and their subsequent re-incorporation as chain initiators does not make a major impact on the product distribution.

  • Fischer-Tropsch synthesis with an iron catalyst: Incorporation of ethene into higher Carbon Number alkanes
    Catalysis Letters, 1991
    Co-Authors: Li Min Tau, Hossein A. Dabbagh, Birbal Chawla, Burtron H. Davis
    Abstract:

    Tracer studies with C labeled ethene show that for synthesis over a doubly promoted iron catalyst at 7 atm and ca. 60% CO conversion, higher Carbon Number products are formed from ethene initiation. About 10% of the added ethene (ethene/CO ∼ 0.02) is incorporated into C5+ products and that ca. 85% of the ethene that is incorporated does so by initiating chain growth.