• <tr id="yyy80"></tr>
  • <sup id="yyy80"></sup>
  • <tfoot id="yyy80"><noscript id="yyy80"></noscript></tfoot>
  • 99热精品在线国产_美女午夜性视频免费_国产精品国产高清国产av_av欧美777_自拍偷自拍亚洲精品老妇_亚洲熟女精品中文字幕_www日本黄色视频网_国产精品野战在线观看 ?

    Application of Discrete Lumped Kinetic Modeling on Vacuum Gas Oil Hydrocracking

    2013-07-25 10:07:36HanLongnianFangXiangchenPengChongZhaoTao
    中國煉油與石油化工 2013年2期
    關鍵詞:乳粉現(xiàn)行保健食品

    Han Longnian; Fang Xiangchen; Peng Chong; Zhao Tao

    (1. Liaoning Shihua University, Fushun, Liaoning 113001; 2. SINOPEC Fushun Research Institute of Petroleum and Petrochemicals)

    Application of Discrete Lumped Kinetic Modeling on Vacuum Gas Oil Hydrocracking

    Han Longnian1; Fang Xiangchen2; Peng Chong2; Zhao Tao1

    (1. Liaoning Shihua University, Fushun, Liaoning 113001; 2. SINOPEC Fushun Research Institute of Petroleum and Petrochemicals)

    The kinetic model of vacuum gas oil (VGO) hydrocracking based on discrete lumped approach was investigated, and some improvement was put forward at the same time in this article. A parallel reaction scheme to describe the conversion of VGO into products (gases, gasoline, and diesel) proposed by Orochko was used. The different experimental data were analyzed statistically and then the product distribution and kinetic parameters were simulated by available data. Furthermore, the kinetic parameters were correlated based on the feed property, reaction temperature, and catalyst activity. An optimization code in Matlab 2011b was written to fine-tune these parameters. The model had a favorable ability to predict the product distribution and there was a good agreement between the model predictions and experiment data. Hence, the kinetic parameters indeed had something to do with feed properties, reaction temperature and catalyst activity.

    hydrocracking; kinetic modeling; vacuum gas oil (VGO); optimization code; parallel reaction scheme

    1 Introduction

    Faced with a growing demand for middle distillate and an increasing production of heavy crude oils, the hydrocracking process has become one of the most important secondary petroleum refining processes. This process is versatile, flexible and can be strongly adapted to inferior feed oil with a strong capability to convert the heavy, high-boiling, and high EBP (end boiling point) feedstock to smaller, lower-boiling ones like qualified jet fuel, diesel, lubrication base oil, and naphtha for chemical use[1]. Hydrocracking takes place over a dual-functional catalyst in a hydrogen-rich, high temperature atmosphere, with other reactions, including hydrodesulfurization, hydrodenitrogenation and other hydrotreating reactions, occurring simultaneously[2]. Despite the successful application of hydrocracking technology in commercial scale, the research on its reaction mechanism and reaction kinetics still lags behind the customer needs.

    There are various kinetic models for the VGO hydrocracking reported in the literature, and the lumped model and detailed molecular model[3]are regarded as two main approaches being studied for a long time. Moreover, all of the hydrocracking kinetic models could be included in the two approaches. Among them, the lumped models incorporate the fixed lumped models, discrete lumped models[4-7]and continuous mixtures involved lumped models[8-10]. For the hydrocracking models based on the lumping technique, these physical properties such as true boiling point (TBP), carbon number (CN), and molecular weight[11]are usually adopted to divide discrete pseudocomponents (lumps). For the fixed lumped model and discrete lumped model, the major disadvantage is that a change in the cutting scheme of the hydrocracker products or in the number of products requires reformulating the model parameters to refit the data. The so-called continuous lumped model is a general case developed from the discrete lumped model, which allows for prediction of the entire distillation curve, but the dependency of model parameters on feed properties still exists. Furthermore, the distillation curves of heavy oils are not accurate when the feedstock is a mixed oil consisting of VGO, CGO, DAO and other fractions. Detailed approaches include the structure oriented lumped models[12]and the single event models[13-14], which express the chemical transformations in terms of typical molecular structures and elementarysteps of cation chemistry, respectively. For a relatively large number of pseudo-components the analytical information and experimental data are required, which impose restrictions on their applications to hydrocracking of real feedstocks.

    The complexity of real feedstocks suggests that lumped model will continue to be used for the research on VGO hydrocracking kinetics. However, detailed approaches need to be studied more precisely in order to obtain a better understanding of hydrocracking kinetics and provide an idea to optimize lumped model for prediction of hydrocracking product properties. A good kinetic model is a useful tool for reactor design, simulation, and optimization of oil refining processes.

    To have a better understanding of the VGO hydrocracking, in this work we conducted some experiments in a pilot plant equipped with two downflow fixed-bed reactors and developed a discrete lumped kinetic model, which will be presented in further papers.

    2 Experimental Data and Kinetic Model

    2.1 Experimental setup and feedstock

    The experiments were conducted in a single-stage series fixed-bed high-pressure pilot plant, which is shown schematically in Figure 1. Hydrocracking was conducted in a downflow mode of operation. The hydrotreating catalyst was loaded in a hydrotreating reactor and the hydrocracking catalyst (A) was loaded in a hydrocracking reactor. The reactor temperature was controlled at the desired level by using a three-zone electric furnace providing an isothermal temperature condition along the reaction section. The temperature inside the reactor was measured by a movable axial thermocouple located inside the reactor. Three typical heavy VGO samples, including Iranian VGO, Saudi VGO and mixed oil (Iranian VGO: CGO=8:2 sampled from Zhenhai refinery), were chosen as the feed. Main properties of these feedstocks are listed in Table 1. These feedstocks had high density, EBP, BMCI and sulfur content so that severe hydrogenation operating conditions were needed in order to achieve the expected conversion degree and index requirements of product properties. Hydrogen gas was provided from an electrolysis hydrogen source, with the hydrogen purity exceeding 99.9%.

    Figure 1 Experimental setup for high-pressure hydrocracking experiment

    Table 1 Main properties of feedstock

    2.2 Some properties of hydrocracking catalyst

    There were several advanced hydrocracking catalysts with high middle distillate yield, and the hydrocracking catalyst A was a new generation catalyst developed on the base of reference catalyst by modifying the support (Si/Al) and Y zeolite, which was a W/Ni commercial catalyst employed in the experiments (with a specific surface area of 200 m2/g, a pore volume of 0.28 cm3/g, and a mean pore diameter of 1.5—1.7 mm). The catalyst A was loaded into the hydrocracker and activated in situ by sulfiding with kerosene containing CS2. This catalyst had high hydrogenation performance, high middle distillate yield, and suitable activity and stability, and demonstrated strong adaptability to inferior feedstock. It had been used in many hydrocrackers to deliver qualified middle distillates and hydrocracked residue with low BMCI value.

    2.3 Experimental data of hydrocracking

    Experiments on hydrocracking of Iranian VGO at different conversion rates were carried out under the operating condition specifying a partial hydrogen pressure of 15.7 MPa, a total LHSV of 1.5 h-1and a total H2/oil ratio of 1 500:1. Moreover, the nitrogen content of hydrotreated oil was controlled at around 10 μg/g. The products were analyzed by true boiling point distillation, with the product distribution presented in Table 2. It can be seen from Table 2 that the VGO conversion increased following the increase of reaction temperature, which was accompanied by an increase of kerosene yield but a decrease of diesel yield. Meanwhile, it is obvious that the middle distillate yield increased when the hydrocracking temperature increased from 381 ℃ to 390 ℃ and these results were consistent with the catalytic activity of the hydrocracking catalyst A.

    Table 2 Product yield distribution of Iran VGO hydrocracking

    2.4 Kinetic model of VGO hydrocracking

    In this study, the kinetic model developed by Orochko[15]was used to simulate the product distribution in hydrocracking process. The hydrocracking kinetics of vacuum gas oil from Iranian crude oils was studied in a fixed-bed reactor over the hydrocracking catalyst A using a firstorder kinetic scheme involving four lumps. The reaction scheme is shown in Figure 2. Theoretically speaking, the four lumped kinetic model schemes should include a series of reactions and parallel reactions. But the hydrocracking catalyst A has low cracking activity and rarely takes part in secondary cracking reaction. So only the parallel reaction of heavy oil cracking was considered in the model scheme, while ignoring the secondary reactions, namely the formation of diesel lump to gasoline, the gas lump, and gasoline lump to gas lump.

    Figure 2 Reaction scheme for hydrocracking lump-kinetic model

    In this study, gases lump (include LPG and off-test),gasoline lump (light and heavy naphtha), and diesel lump (kerosene and diesel) were considered as three of four lumps. Moreover, the hydrocracker products and yield are shown in Table 2. The experimental data of hydrocracking process were used to model the kinetic parameters of hydrocracking reactions.

    The hydrocracking process took place according to a retarded first-order reaction, which was the equation developed by Orochko[1]. Based on this method, the yields of diesel lump and gasoline lump can be expressed by the total conversionyand macro-kinetic parameters.

    in whichZ,X, andGare experimental yield of diesel lump, gasoline lump and gases lump, respectively, andyis the conversion rate of VGO.

    Among them, the macrokinetic parameters (k′andk″) depend on feed properties, process temperature and catalyst characteristics. All kinetic model parameters are determined by experimental data and simulated by an optimization procedure written in the Matlab 2011b. Furthermore, the objective function which determines the optimized model parameters is defined as follows.

    3 Results and Discussion

    The operating conditions and experimental data of a pilotplant scale hydrocracker were used to calculate and validate the model parameters. The results of fine-tuning are shown in Table 3. By using these parameters, the product distribution can be calculated. A comparison between the model results for predicting the product yields is also shown in Table 3. It can be seen from Table 3 that there was an extraordinarily good agreement between model prediction results and experimental data. The absolute relative deviation (ARD) and mean square error (OBJ) of the model for predicting the product yields are defined as follows:

    in which yexpand ymodare experimental and model yield of product, respectively. The ARD and OBJ of model predictions are shown in Table 3. It can be seen from Table 3 that the calculation error was small enough to meet the requirements of the model.

    Table 3 Model macrokinetic parameters and standard deviation

    Sincek′andk″are kinetic factors with similar meaning to the rate constants, the relation between macrokinetic parameters and reaction temperature based on the Arrhenius equation should be studied. The correlation between -ln(k′,k″) and 1/Tis presented in Figure 3. It can be obviously seen that the macrokinetic parameterk′could satisfy the Arrhenius equation along with high related coefficient (R2=0.9905), but there was not a close relationship between macrokinetic parameterk″and reaction temperature because of its relatively low coefficient (R2=0.6899). It might occur because the model parameter (k″) was not only a function of reaction temperature, but was also related with other process conditions. This experiment studied only the process conditions of different reaction temperatures so that the complete correlation could not be fully reflected. Perhaps, a further research work needs tobe accomplished.

    Figure 3 Relationship between -ln(k′, k″) and 1/T

    3.2 Correlation of kinetic modeling parameters

    It has been referred to in the previous research[7]that the macrokinetic parameters (k′andk″) depend upon the feedstock property, the reaction temperature, and the nature of catalyst. Furthermore,k′andk″are kinetic factors with similar meaning to the rate constants.

    So a correlation function was put forward to calculate the macrokinetic parameters. Among them, the characteristic factor (Kf) and the volume-mean boiling point (Tv) functioned as factors which could mainly represent the feedstock property. The weight percent conversion of VGO (Xf), reaction temperature (T), and zeolite content of catalyst are also included in this empirical correlation.KfandTVare calculated by the following formulas and the calculated results are listed in Table 1.

    Through correlation and selection of various methods, the two empirical model correlations were chosen, which was an innovative idea adopted in this paper. The empirical correlations aboutk′andk″are listed as follows:

    據(jù)了解,我國保健食品注冊管理制度已經(jīng)實行了20年,約1.6萬個產品獲得了批準。現(xiàn)行注冊與備案的雙軌管理制度,也為產品準入、市場發(fā)展提供了強大活力。此外,嬰幼兒配方乳粉、特殊醫(yī)學用途配方食品注冊形成了科學完善的管理制度,實現(xiàn)了注冊管理的平穩(wěn)過渡。

    whereA1,A2,A3,B1,B2, andB3 are model parameters, which are calculated from the experimental data;wis the zeolite content in catalyst.

    The hydrocracking experiments were carried out on different feedstocks, with the reaction temperature and experimental data shown in Table 4. Firstly, the macrokinetic parameters (k′andk″) were calculated from experimental data listed in Table 4 and then the model parameters were correlated by the nonlinear least square method described in the Matlab 2011b. According to the calculated value listed in Table 4, the macrokinetic parameters (k′andk″) optimized from experimental data of three typical feedstocks were suited quite well to implementing the model calculation because of its low OBJ.

    Table 4 Hydrocracking experiments on different feedstocks and kinetic parameters

    And then the model parameters describing the relationship between macrokinetic parameters and feedstock properties, catalyst activity, and reaction temperature were simulated by an optimization procedure written in the Matlab 2011b. The objective function which determines the optimized model parameters is defined as mentioned previously. Judging from the optimization results listed in Table 5, it has good prediction accuracy which is appro-priate enough for meeting the model not only in terms of the ARD value but also the OBJ value.

    Figure 5 Model gasoline yield versus experimental gasoline yield

    Table 5 Model parameters of macrokinetic parameters (k′, k″)

    3.3 Validation of kinetic modeling

    After the kinetic modeling parameters were calculated from the above-mentioned experimental data, the kinetic model could be written as follows:

    By using these modeling parameters, the hydrocracking product distribution can be calculated. The comparison between the calculated results and the experimental data are shown in Figures 4—5. It can be seen from the data depicted in Figures 4—5 that there was a good agreement between model diesel predictions and experimental data.

    Figure 4 Model diesel yield versus experimental diesel yield

    But the model estimation relating to the gasoline lump and the gas lump was less reliable than the diesel lump especially with respect to the gas lump. Furthermore, the kinetic modeling cannot realize prediction when the products cutting scheme was changed.

    So far there would not be a model that can realize the prediction on different catalysts, feedstocks, and other factors. Despite the vast commercial application prospects of hydrocracking catalyst A, this model also does not have practicability for industrial hydrocrackers because of constraints related with internal diffusion, external diffusion and other factors.

    In general, this model can be only suitable for prediction of the hydrocracking catalyst at some extent. There is still a long way to establish a perfect kinetic model of hydrocracking.

    4 Conclusions

    (1) In this article, a discrete lumped kinetic approach was used to simulate the kinetics of hydrocracking reactions in a pilot-plant hydrocracker. The data sets were statistically analyzed and then an optimization code was applied to determine the model parameters. The model prediction was validated by experimental data and calculated data based on the model parameters.

    (2) Furthermore, the effect of feedstock properties, such as characteristic factor (K), volume-mean boiling point (TV), reaction temperature (T) and other parameters were also correlated in the model. The ARD and OBJ of the model prediction were calculated and the results verified the accuracy of the model parameters and model suitability for predicting the product distribution.

    Acknowledgements:Thanks to the fund of “National ‘Twelfth Five-Year’ Plan for Science & Technology Support” (No. 2012BAE05B04) and “Research on Hydrocracking Catalysts Grading Technology” undertaken by Fushun Research Institute of Petroleum and Petrochemicals (FRIPP) supported by SINOPEC (No. 101102).

    [1] Kumar H, Froment G F. Mechanistic kinetic modeling of the hydrocracking of complex feedstocks, such as vacuum gas oils[J]. Ind Eng Chem Res, 2007, 46(18): 5881-5897

    [2] Ancheyta J, Sanchez S, Rodriguez M A. Kinetic modeling of hydrocracking of heavy oil fractions: A review[J]. Catalysis Today, 2005, 109(1-4): 76-92

    [3] Schweitzer J M, Galtier P, Schweich D. A single event kinetic model for the hydrocracking of paraffins in a three-phase reactor [J]. Chem Engng Sci, 1999, 54(13/14): 2441-2452

    [4] Sadighi S, Ahmad A, Mohaddecy S R S. 6-Lump kinetic model for a commercial vacuum gas oil hydrocracker[J]. International Journal of Chemical Reactor Engineering, 2010, 8(A1): 1-24

    [5] Sadighi S, Ahmad A, Rashidzadeh M. 4-Lump kinetic model for vacuum gas oil hydrocracker involving hydrogen consumption[J]. Korean J Chem Eng, 2010, 27(4): 1099-1108

    [6] Moghadassi A R, Amini N, Fadavi O, et al. The application of the discrete lumped kinetic approach for the modeling of a vacuum gas oil hydrocracker unit[J]. Petroleum Science and Technology, 2011, 29(23): 2416-2424

    [7] Kumar A, Sinha S. Steady state modeling and simulation of hydrocracking reactor[J]. Petroleum & Coal, 2012, 54(1): 59-64

    [8] Elizalde I, Rodriguez M A, Ancheyta J. Application of continuous kinetic lumping modeling to moderate hydrocracking of heavy oil[J]. Applied Catalysis A: General, 2009, 365(2): 237-242

    [9] Sadeghi M T, Shahhosseini S, Behroozshad F. Continuous lumping model of an industrial refinery isomax reactor[J]. Iranian Journal of Chemical Engineering, 2010, 7(2): 39-50

    [10] Elizaldea I, Rodríguezb M A, Ancheyta J. Modeling the effect of pressure and temperature on the hydrocracking of heavy crude oil by the continuous kinetic lumping approach[J]. Applied Catalysis A: General, 2010, 382(2): 205-212

    [11] Sadighi S, Ahmad A, Irandoukht A. Kinetic study on a commercial amorphous hydrocracking catalyst by weighted lumping strategy[J]. International Journal of Chemical Reactor Engineering, 2010, 8(1): 1-24

    [12] Jaffe S B. Extension of structure-oriented lumping to vacuum residue[J]. Ind Eng Chem Res, 2005, 44(26): 9840-9852

    [13] Mitsios M, Guillaume D, Galtier P, et al. Single-event microkinetic model for long-chain paraffin hydrocracking and hydroisomerization on an amorphous Pt/SiO2·Al2O3catalyst[J]. Ind Eng Chem Res, 2009, 48(7): 3284-3292

    [14] Guillaume D, Valery E, Verstraete J J, et al. Single event kinetic modeling without explicit generation of large networks: Application to hydrocracking of long paraffins[J]. Oil & Gas Science and Technology, 2011, 66(3): 399-422

    [15] Orochko D I, Perezhigina I Y, Rogov S P, et al. Applied over-all kinetics of hydrocracking of heavy petroleum distillates[J]. Khimiya I Tekhnologiya Toplivi Masel, 1970, 8(6): 561-565 (in Russian)

    Recieved date: 2012-12-27; Accepted date: 2013-02-05.

    Professor Fang Xiangchen, E-mail: fangxiangchen.fshy@sinopec.com.

    猜你喜歡
    乳粉現(xiàn)行保健食品
    牛、羊乳粉的DSC熱學性質比較及摻假分析
    食品科學(2023年4期)2023-03-06 12:49:32
    抓現(xiàn)行
    微生物法測定嬰幼兒乳粉葉酸含量的不確定度評估
    新疆伊犁馬乳粉脂肪酸組成和含量分析
    保健食品說蕎麥
    淺談我國現(xiàn)行的房產稅
    活力(2019年15期)2019-09-25 07:21:38
    減肥類保健食品中25種非法添加化學物質的UPLC-DAD快速篩查
    中成藥(2018年12期)2018-12-29 12:26:10
    最適合胖人去脂減肥的保健食品
    被抓了現(xiàn)行
    現(xiàn)行企業(yè)內部控制制度探討
    99在线人妻在线中文字幕| 91av网站免费观看| 黄片大片在线免费观看| svipshipincom国产片| 亚洲av成人一区二区三| 成人av一区二区三区在线看| av欧美777| 欧美日韩中文字幕国产精品一区二区三区 | 在线观看免费视频日本深夜| 搡老乐熟女国产| 桃色一区二区三区在线观看| 男人操女人黄网站| 十分钟在线观看高清视频www| 久久青草综合色| 亚洲欧美激情在线| 亚洲av美国av| 国产精华一区二区三区| 久久人人爽av亚洲精品天堂| 老汉色∧v一级毛片| 宅男免费午夜| 如日韩欧美国产精品一区二区三区| 国产高清videossex| 日韩精品中文字幕看吧| 美女大奶头视频| 成在线人永久免费视频| 免费在线观看亚洲国产| 国产熟女xx| 欧美+亚洲+日韩+国产| 成年人免费黄色播放视频| 两性夫妻黄色片| av天堂久久9| 成年版毛片免费区| 国产一区在线观看成人免费| av网站免费在线观看视频| av网站在线播放免费| 老司机亚洲免费影院| 涩涩av久久男人的天堂| 国产伦人伦偷精品视频| 欧美中文日本在线观看视频| 在线十欧美十亚洲十日本专区| 国产精品久久久av美女十八| 18禁美女被吸乳视频| 99久久精品国产亚洲精品| 中文字幕高清在线视频| 国产野战对白在线观看| 满18在线观看网站| 精品午夜福利视频在线观看一区| 精品福利观看| 国产av一区二区精品久久| 交换朋友夫妻互换小说| 中文字幕最新亚洲高清| 亚洲中文字幕日韩| 国产一区二区三区综合在线观看| 热99re8久久精品国产| 一级毛片精品| 精品人妻1区二区| 午夜福利在线免费观看网站| 成年女人毛片免费观看观看9| 91九色精品人成在线观看| 乱人伦中国视频| 午夜福利免费观看在线| 中文字幕色久视频| 国产精品1区2区在线观看.| 国产精品香港三级国产av潘金莲| 男人的好看免费观看在线视频 | 亚洲熟妇熟女久久| x7x7x7水蜜桃| 不卡av一区二区三区| 在线视频色国产色| 亚洲国产欧美一区二区综合| 高潮久久久久久久久久久不卡| 欧美日韩黄片免| 99精品欧美一区二区三区四区| 久久精品亚洲av国产电影网| 午夜免费鲁丝| 欧美亚洲日本最大视频资源| 美女高潮到喷水免费观看| 中文字幕人妻熟女乱码| 香蕉久久夜色| 精品一品国产午夜福利视频| 一区二区三区精品91| 亚洲情色 制服丝袜| 亚洲精品国产区一区二| 91成年电影在线观看| 精品久久久久久电影网| 久久久久国产精品人妻aⅴ院| 精品一区二区三卡| 超色免费av| 50天的宝宝边吃奶边哭怎么回事| 韩国精品一区二区三区| а√天堂www在线а√下载| 婷婷丁香在线五月| 亚洲欧美激情在线| 亚洲av电影在线进入| 无人区码免费观看不卡| 成人国语在线视频| 日韩欧美三级三区| 女性生殖器流出的白浆| 久久精品国产亚洲av高清一级| 午夜福利在线观看吧| www.www免费av| 午夜精品在线福利| 两性夫妻黄色片| 国产国语露脸激情在线看| 性少妇av在线| 亚洲成国产人片在线观看| 最新在线观看一区二区三区| 亚洲成a人片在线一区二区| 在线观看免费午夜福利视频| 99久久精品国产亚洲精品| www.精华液| 亚洲精品国产色婷婷电影| 一区二区三区国产精品乱码| 脱女人内裤的视频| tocl精华| 别揉我奶头~嗯~啊~动态视频| 精品无人区乱码1区二区| 亚洲人成伊人成综合网2020| 狂野欧美激情性xxxx| 国产av一区在线观看免费| 咕卡用的链子| 黄网站色视频无遮挡免费观看| 久久久精品国产亚洲av高清涩受| 国产欧美日韩综合在线一区二区| 亚洲第一欧美日韩一区二区三区| 91大片在线观看| 又黄又粗又硬又大视频| 免费在线观看完整版高清| av福利片在线| 一区二区三区激情视频| 在线天堂中文资源库| 日本撒尿小便嘘嘘汇集6| 欧美国产精品va在线观看不卡| 日韩欧美一区视频在线观看| 欧美日韩福利视频一区二区| 99国产精品一区二区三区| 在线视频色国产色| 美女高潮喷水抽搐中文字幕| 激情在线观看视频在线高清| 欧美日韩av久久| 曰老女人黄片| av天堂在线播放| 天堂动漫精品| 久久精品成人免费网站| 波多野结衣一区麻豆| 最新在线观看一区二区三区| 欧美中文综合在线视频| 成人精品一区二区免费| 曰老女人黄片| 亚洲av成人不卡在线观看播放网| 亚洲成人国产一区在线观看| 99久久精品国产亚洲精品| 成年版毛片免费区| 午夜福利免费观看在线| 国产精品一区二区在线不卡| 黑人巨大精品欧美一区二区蜜桃| www.www免费av| 真人做人爱边吃奶动态| av视频免费观看在线观看| 香蕉国产在线看| 色综合婷婷激情| 午夜福利欧美成人| 午夜老司机福利片| 热99国产精品久久久久久7| 久久中文看片网| 一进一出抽搐动态| 国产1区2区3区精品| 黑人巨大精品欧美一区二区蜜桃| 男人舔女人的私密视频| 黄片小视频在线播放| 男女之事视频高清在线观看| 日韩三级视频一区二区三区| 日韩一卡2卡3卡4卡2021年| 丁香六月欧美| 无遮挡黄片免费观看| 国产av精品麻豆| 欧美成人免费av一区二区三区| 麻豆一二三区av精品| 乱人伦中国视频| 性色av乱码一区二区三区2| 国产精品久久电影中文字幕| 黄色 视频免费看| 亚洲精品国产精品久久久不卡| 99热国产这里只有精品6| 色综合婷婷激情| 亚洲第一av免费看| 成人黄色视频免费在线看| 丝袜美足系列| 一进一出好大好爽视频| aaaaa片日本免费| 亚洲黑人精品在线| 精品久久久久久成人av| 91字幕亚洲| 久久人妻福利社区极品人妻图片| 久久热在线av| 久久欧美精品欧美久久欧美| 在线观看午夜福利视频| 咕卡用的链子| 亚洲精品一二三| 亚洲人成电影免费在线| 咕卡用的链子| 老汉色av国产亚洲站长工具| 欧美日韩亚洲国产一区二区在线观看| 丝袜美足系列| 国产1区2区3区精品| 大陆偷拍与自拍| 在线观看一区二区三区激情| 久久亚洲精品不卡| 国产蜜桃级精品一区二区三区| 亚洲视频免费观看视频| 国产三级在线视频| 9热在线视频观看99| 在线观看舔阴道视频| 午夜福利影视在线免费观看| 久久青草综合色| 91九色精品人成在线观看| 国产成人免费无遮挡视频| 免费在线观看视频国产中文字幕亚洲| 亚洲va日本ⅴa欧美va伊人久久| 亚洲av成人一区二区三| 亚洲专区字幕在线| 亚洲熟妇中文字幕五十中出 | 国产免费现黄频在线看| 黄色丝袜av网址大全| 悠悠久久av| 99国产综合亚洲精品| 欧洲精品卡2卡3卡4卡5卡区| 亚洲精品在线观看二区| 国产精品成人在线| 黄片播放在线免费| 午夜a级毛片| 麻豆国产av国片精品| 久久精品亚洲精品国产色婷小说| 男女床上黄色一级片免费看| svipshipincom国产片| 日韩免费av在线播放| 日韩av在线大香蕉| 9191精品国产免费久久| 亚洲成av片中文字幕在线观看| 最新在线观看一区二区三区| 丝袜在线中文字幕| 一级,二级,三级黄色视频| 麻豆一二三区av精品| avwww免费| 免费在线观看黄色视频的| 水蜜桃什么品种好| 日韩欧美免费精品| 精品国产乱子伦一区二区三区| 国产野战对白在线观看| 麻豆国产av国片精品| 日韩精品中文字幕看吧| 欧美日韩中文字幕国产精品一区二区三区 | 欧美亚洲日本最大视频资源| 69av精品久久久久久| 精品一区二区三区av网在线观看| 在线观看一区二区三区| 美女 人体艺术 gogo| 激情在线观看视频在线高清| 女性生殖器流出的白浆| 国产在线精品亚洲第一网站| 亚洲国产毛片av蜜桃av| 后天国语完整版免费观看| 两性午夜刺激爽爽歪歪视频在线观看 | 十分钟在线观看高清视频www| 国产视频一区二区在线看| 国产精品爽爽va在线观看网站 | 性色av乱码一区二区三区2| 淫妇啪啪啪对白视频| 好男人电影高清在线观看| 国产成人精品久久二区二区91| 人人妻人人添人人爽欧美一区卜| 男人舔女人下体高潮全视频| tocl精华| 国产精品1区2区在线观看.| 久久精品人人爽人人爽视色| 黑人欧美特级aaaaaa片| 国产高清激情床上av| 国产精品秋霞免费鲁丝片| 又紧又爽又黄一区二区| 久久中文字幕人妻熟女| av天堂久久9| 女人高潮潮喷娇喘18禁视频| 久久性视频一级片| 曰老女人黄片| 午夜亚洲福利在线播放| 精品高清国产在线一区| 亚洲男人天堂网一区| 女人被狂操c到高潮| 午夜两性在线视频| 久久精品91无色码中文字幕| 在线十欧美十亚洲十日本专区| 19禁男女啪啪无遮挡网站| 欧洲精品卡2卡3卡4卡5卡区| 国产一区在线观看成人免费| e午夜精品久久久久久久| 超碰97精品在线观看| 69av精品久久久久久| netflix在线观看网站| 岛国视频午夜一区免费看| 精品日产1卡2卡| 人人妻,人人澡人人爽秒播| 国产精品偷伦视频观看了| 日韩国内少妇激情av| 国产一区二区在线av高清观看| 正在播放国产对白刺激| 国产免费av片在线观看野外av| e午夜精品久久久久久久| 12—13女人毛片做爰片一| 一个人观看的视频www高清免费观看 | 淫妇啪啪啪对白视频| 日韩欧美一区视频在线观看| 99久久综合精品五月天人人| 涩涩av久久男人的天堂| 国产精品秋霞免费鲁丝片| 身体一侧抽搐| 高清毛片免费观看视频网站 | 国产精品自产拍在线观看55亚洲| 免费一级毛片在线播放高清视频 | 真人一进一出gif抽搐免费| 9热在线视频观看99| 少妇裸体淫交视频免费看高清 | 91精品三级在线观看| 国产精品永久免费网站| av在线播放免费不卡| 女警被强在线播放| 激情视频va一区二区三区| 亚洲黑人精品在线| 精品福利观看| 欧美在线一区亚洲| 欧美日韩av久久| 中文字幕另类日韩欧美亚洲嫩草| 国产亚洲精品一区二区www| 啦啦啦 在线观看视频| 丰满迷人的少妇在线观看| 午夜福利欧美成人| 性欧美人与动物交配| 成人国产一区最新在线观看| 在线观看免费午夜福利视频| 日韩免费av在线播放| 成人黄色视频免费在线看| 黄网站色视频无遮挡免费观看| 久久久久久久精品吃奶| 欧美精品啪啪一区二区三区| 男女之事视频高清在线观看| 欧美国产精品va在线观看不卡| 国产一区二区三区在线臀色熟女 | 18禁美女被吸乳视频| 午夜日韩欧美国产| 午夜福利免费观看在线| 窝窝影院91人妻| 99热只有精品国产| 欧美日韩一级在线毛片| 国产片内射在线| 真人做人爱边吃奶动态| 在线观看www视频免费| 国产99白浆流出| 一区福利在线观看| 久久久久久久久久久久大奶| 亚洲欧洲精品一区二区精品久久久| 欧美中文日本在线观看视频| 国产精品美女特级片免费视频播放器 | 别揉我奶头~嗯~啊~动态视频| 欧美成人午夜精品| 在线观看午夜福利视频| 成人特级黄色片久久久久久久| 久久久久国内视频| 亚洲人成网站在线播放欧美日韩| 色精品久久人妻99蜜桃| 亚洲精品成人av观看孕妇| 免费搜索国产男女视频| 成年版毛片免费区| 老鸭窝网址在线观看| 国产精品国产高清国产av| 18禁美女被吸乳视频| 亚洲自偷自拍图片 自拍| 丝袜美腿诱惑在线| 久久精品亚洲精品国产色婷小说| 日本a在线网址| 亚洲一区二区三区不卡视频| 少妇裸体淫交视频免费看高清 | 久久久久久大精品| 亚洲av片天天在线观看| 国内毛片毛片毛片毛片毛片| 热99国产精品久久久久久7| 叶爱在线成人免费视频播放| 两性午夜刺激爽爽歪歪视频在线观看 | 99精品在免费线老司机午夜| 日韩三级视频一区二区三区| 在线国产一区二区在线| 天天添夜夜摸| 一本综合久久免费| 狠狠狠狠99中文字幕| www日本在线高清视频| 黄色视频,在线免费观看| 夜夜躁狠狠躁天天躁| 亚洲自拍偷在线| 在线观看日韩欧美| 老熟妇仑乱视频hdxx| cao死你这个sao货| 美女福利国产在线| 精品国产乱码久久久久久男人| 精品久久久精品久久久| 欧美成人性av电影在线观看| 老司机在亚洲福利影院| 亚洲人成电影观看| 免费在线观看影片大全网站| 国产精品美女特级片免费视频播放器 | 美女午夜性视频免费| 精品久久久久久成人av| 他把我摸到了高潮在线观看| 人人澡人人妻人| 一二三四社区在线视频社区8| 日日爽夜夜爽网站| 嫩草影院精品99| 国产免费男女视频| 亚洲七黄色美女视频| 亚洲av五月六月丁香网| 91国产中文字幕| 女人被躁到高潮嗷嗷叫费观| 久久这里只有精品19| 色在线成人网| 99久久综合精品五月天人人| 欧美午夜高清在线| 人妻丰满熟妇av一区二区三区| 五月开心婷婷网| 精品卡一卡二卡四卡免费| 国产伦人伦偷精品视频| 日韩精品中文字幕看吧| 国产精华一区二区三区| 伊人久久大香线蕉亚洲五| 桃色一区二区三区在线观看| 亚洲国产精品sss在线观看 | 国产精品久久久av美女十八| 法律面前人人平等表现在哪些方面| 黄色女人牲交| 黄色a级毛片大全视频| 91精品三级在线观看| 亚洲中文日韩欧美视频| 日本免费a在线| 色老头精品视频在线观看| 1024视频免费在线观看| 欧美亚洲日本最大视频资源| 午夜老司机福利片| 亚洲国产精品999在线| 日本三级黄在线观看| 18禁国产床啪视频网站| 99精品在免费线老司机午夜| 免费少妇av软件| 精品日产1卡2卡| 国产欧美日韩一区二区三| 亚洲情色 制服丝袜| 在线天堂中文资源库| 亚洲av片天天在线观看| 99国产精品一区二区蜜桃av| 亚洲精品在线美女| 色婷婷av一区二区三区视频| 一a级毛片在线观看| 成人18禁高潮啪啪吃奶动态图| 国产精品九九99| 又黄又粗又硬又大视频| 视频在线观看一区二区三区| 精品电影一区二区在线| 欧美中文日本在线观看视频| 亚洲激情在线av| 啦啦啦在线免费观看视频4| 国产一区二区三区在线臀色熟女 | 后天国语完整版免费观看| 亚洲伊人色综图| 欧美另类亚洲清纯唯美| 十八禁网站免费在线| 久久精品国产综合久久久| 欧美在线一区亚洲| 黄色 视频免费看| 夜夜夜夜夜久久久久| 午夜福利欧美成人| 夜夜躁狠狠躁天天躁| 成在线人永久免费视频| 欧美日韩精品网址| tocl精华| 亚洲国产精品sss在线观看 | 精品人妻在线不人妻| 免费观看精品视频网站| 男女之事视频高清在线观看| 天堂俺去俺来也www色官网| 操出白浆在线播放| 午夜福利欧美成人| xxxhd国产人妻xxx| 免费女性裸体啪啪无遮挡网站| 九色亚洲精品在线播放| 十八禁人妻一区二区| 黄色 视频免费看| 在线av久久热| 亚洲国产看品久久| 黄色丝袜av网址大全| 五月开心婷婷网| 超碰成人久久| 黑人巨大精品欧美一区二区mp4| 国产精品偷伦视频观看了| 成人国产一区最新在线观看| 亚洲国产中文字幕在线视频| 久久香蕉国产精品| 热99国产精品久久久久久7| 一区二区三区精品91| 自线自在国产av| 精品欧美一区二区三区在线| 中文字幕人妻丝袜一区二区| 国产免费男女视频| 国产精品成人在线| 久久久国产欧美日韩av| 国产精品一区二区在线不卡| 久久久久久大精品| 一级a爱视频在线免费观看| 欧美人与性动交α欧美精品济南到| 国产亚洲精品第一综合不卡| 最新美女视频免费是黄的| 久久久久久大精品| 久久国产精品影院| 99热国产这里只有精品6| 日韩 欧美 亚洲 中文字幕| 9色porny在线观看| 久久中文字幕人妻熟女| 亚洲熟女毛片儿| e午夜精品久久久久久久| 91麻豆精品激情在线观看国产 | 亚洲一码二码三码区别大吗| 12—13女人毛片做爰片一| 欧美一级毛片孕妇| 国产成年人精品一区二区 | 午夜免费激情av| 国产深夜福利视频在线观看| 法律面前人人平等表现在哪些方面| 欧美激情极品国产一区二区三区| 美女国产高潮福利片在线看| 麻豆国产av国片精品| 久久国产精品男人的天堂亚洲| 国产在线精品亚洲第一网站| 一夜夜www| 精品国产超薄肉色丝袜足j| 女人被狂操c到高潮| 欧美黑人欧美精品刺激| 亚洲专区字幕在线| 久久午夜亚洲精品久久| 亚洲国产精品999在线| 人人妻人人添人人爽欧美一区卜| а√天堂www在线а√下载| 热re99久久精品国产66热6| 亚洲免费av在线视频| 在线免费观看的www视频| 一本综合久久免费| 两性夫妻黄色片| 国产又爽黄色视频| 中文字幕av电影在线播放| 电影成人av| 亚洲精品在线观看二区| 级片在线观看| 国产成人精品在线电影| 久热爱精品视频在线9| 99热国产这里只有精品6| 午夜a级毛片| 中文字幕高清在线视频| 国产亚洲精品久久久久5区| 精品福利观看| 午夜福利在线观看吧| 欧美精品亚洲一区二区| 麻豆av在线久日| 日韩免费高清中文字幕av| 91成年电影在线观看| 天堂影院成人在线观看| 亚洲国产看品久久| 国产亚洲欧美精品永久| 亚洲熟妇中文字幕五十中出 | 91国产中文字幕| 巨乳人妻的诱惑在线观看| xxxhd国产人妻xxx| 老鸭窝网址在线观看| 亚洲精品一卡2卡三卡4卡5卡| 18禁黄网站禁片午夜丰满| 一进一出好大好爽视频| 又黄又粗又硬又大视频| 99精品久久久久人妻精品| 国产av一区二区精品久久| 精品卡一卡二卡四卡免费| 青草久久国产| av在线播放免费不卡| 国产成人精品久久二区二区免费| 久久精品成人免费网站| 最好的美女福利视频网| 黄片播放在线免费| 人成视频在线观看免费观看| 午夜免费成人在线视频| 亚洲精品国产色婷婷电影| 叶爱在线成人免费视频播放| 免费在线观看影片大全网站| 成人18禁在线播放| 国产亚洲精品久久久久5区| ponron亚洲| 搡老乐熟女国产| 久久精品国产亚洲av高清一级| 久久人人97超碰香蕉20202| 丰满迷人的少妇在线观看| 亚洲一码二码三码区别大吗| 乱人伦中国视频| 50天的宝宝边吃奶边哭怎么回事| 免费搜索国产男女视频| 男女午夜视频在线观看| 精品一区二区三区av网在线观看| 免费搜索国产男女视频| 涩涩av久久男人的天堂| 国产精品电影一区二区三区| 久久精品成人免费网站| 国产又爽黄色视频| 亚洲国产欧美网| 99在线视频只有这里精品首页| 丰满的人妻完整版| 国产免费男女视频|