• <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 ?

    Unified Model of Purification Units in Hydrogen Networks*

    2014-07-18 12:09:48WUSidong吳思東WANGYufei王彧斐andFENGXiao馮霄SchoolofChemicalEngineeringTechnologyXianJiaotongUniversityXian70049ChinaStateKeyLaboratoryofHeavyOilProcessingChinaUniversityofPetroleumBeijing049China

    WU Sidong (吳思東), WANG Yufei (王彧斐)and FENG Xiao (馮霄),**School of Chemical Engineering & Technology, Xi’an Jiaotong University, Xi’an 70049, ChinaState Key Laboratory of Heavy Oil Processing, China University of Petroleum, Beijing 049, China

    Unified Model of Purification Units in Hydrogen Networks*

    WU Sidong (吳思東)1, WANG Yufei (王彧斐)2and FENG Xiao (馮霄)2,**
    1School of Chemical Engineering & Technology, Xi’an Jiaotong University, Xi’an 710049, China2State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Beijing 102249, China

    Purification processes are widely used in hydrogen networks of refineries to increase hydrogen reuse. In refineries, hydrogen purification techniques include hydrocarbon, hydrogen sulfide and CO removal units. In addition, light hydrocarbon recovery from the hydrogen source streams can also result in hydrogen purification. In order to simplify the superstructure and mathematical model of hydrogen network integration, the models of different purification processes are unified in this paper, including mass balance and the expressions for hydrogen recovery and impurity removal ratios, which are given for all the purification units in refineries. Based on the proposed unified model, a superstructure of hydrogen networks with purification processes is constructed.

    purification process, hydrogen network integration, impurity removal ratio, refinery

    1 INTRODUCTION

    In recent years, increasingly strict environmental and product-quality regulations, and the change of crude oil to high-sulfur and heavier oil are forcing refineries to increase their hydrotreating and hydrocracking. The result is that the hydrogen demand is increasing sharply, which made hydrogen become an expensive utility [1].

    To cope with this problem, the effective use of hydrogen is of significant importance. By now, hydrogen network integration (HNI) is recognized as the most effective method for refinery hydrogen management [2]. For hydrogen network integration, process hydrogen streams should be reused as fully as possible to reduce the hydrogen utility consumption. Purification, by upgrading hydrogen concentration of some streams, is an effective way to increase the hydrogen reuse at relative low cost [1, 3].

    In a hydrogen network, in addition to hydrogen concentration, each hydrogen sink (for example, hydrotreating or hydrocracking units) requires also limits on certain impurities such as H2S and CO [2]. Therefore, in refineries, hydrogen purification techniques include hydrocarbon, hydrogen sulfide (H2S) and CO removal units.

    Hydrocarbon removal units include pressure swing adsorption (PSA), membrane and cryogenic process [4]. There are several methods to remove H2S: dry desulfurization, wet desulfurization, bio-desulfurization and desulfurization by membrane. Wet desulfurization process is widely used. This process utilizes an aqueous absorbent in a column to absorb H2S and yields a substantial H2S-free gas [5]. In industrial applications, the CO removal process is usually coupled with a PSA process. Thus, a PSA process can be either with or without CO removal. Currently, light hydrocarbon recovery from hydrogen source streams is a trend to increase economic benefit of a refinery.

    In the work on hydrogen network integration, at first the purification is treated as a fixed process and both the concentration and flowrate of purification streams are termed as fixed values [6-14]. Then, it is realized that a hydrogen network should be optimized with purification processes as a whole to achieve the minimum hydrogen utility consumption [1]. Hydrocarbon removal units were considered first [1, 4, 12]. After that, hydrogen sulfide removal processes were also considered [5]. Up to now, CO removal processes and light hydrocarbon recovery processes are not concerned.

    Because different purification processes have different separation principles (adsorption, membrane, etc.), up to now, each purification process has its own model. Even in the superstructure of a hydrogen network, different purification processes have different blocks [2, 4, 5]. This makes the superstructure complicated and the solving process more difficult.

    Although different purification processes have different separation principles, from the point of view of hydrogen network integration, the main description for each purification process only concerns mass balance and concentration constraints. Therefore, the models of purification processes can be unified, which is just the aim of this paper.

    2 EXISTING MODELS

    2.1 PSA process without CO removal

    The PSA process separates the mixture stream by utilizing an adsorbent with different adsorb abilities for different components. The total mass balance is [2]

    where F is flowrate, the superscript (PSA) means PSAprocess, and the subscript R, in and P denote residual, inlet and product, respectively.

    The mass balance for component i is [2]

    where y is concentration and subscript i means component i.

    The hydrogen recovery ratio R is defined in Eq. (3), which varies according to the feed purity, adsorption pressure and tail gas pressure [3].

    The concentration of hydrogen sulfide is assumed to be identical during the process, that is [2]

    The hydrocarbon components are assumed to be removed at an equal proportion as follows [2].

    It should be noted that CO is not considered in the model.

    2.2 Membrane process

    The membrane separation is operated by adopting a permselective membrane with permeability varying along with components. The total mass balance is [2]

    where superscript memb means membrane process. The mass balance for component i is [2]

    The hydrogen sulfide concentration of the product stream is assumed to be equivalent to the inlet stream [2].

    It should be noted that not only CO but also the removal proportion of each hydrocarbon component are not considered in the model.

    2.3 Desulfurization process

    H2S removal units are usually modeled as mass exchangers. The hydrogen sulfide removed by a desulfurization column is a very tiny part of the mass stream, and therefore the inlet and outlet flowrates of a desulfurization column are assumed to be identical, as shown in Eq. (10) [5].

    where superscript ds means desulfurization process.

    3 THE UNIFIED MODEL OF PURIFICATION PROCESSES

    A purification process usually generates two outputs from the feed (Fin, yin,i), one of which with higher hydrogen concentration is the purified product (FP, yP,i), and the other with lower hydrogen concentration is termed as residual or tail gas (FR, yR,i), as shown in Fig. 1.

    Figure 1 A purification unit

    For a process with only one output like the desulfurization process, it can be taken as a specific case of the unified model with FR=0.

    Then we have the total mass balance as shown in Eq. (12).

    The mass balance for component i is

    The hydrogen recovery ratio R is

    The removal ratio riof component i during the purification process is defined as

    Equations (12) to (15) are the unified model of purification processes. Compared to all the existing models for different kinds of purification processes, it can be seen that the unified model is in full agreement.

    From the above equations, the outlet concentrations (the concentration of the product stream) of hydrogen and other components from a purification process can be calculated by Eqs. (16) and (17), respectively.

    With the unified model of purification processes, all purification processes can be expressed in the same block in the superstructure of a hydrogen network. In this way, the superstructure will be simpler, and the mathematical model for the hydrogen network integration will be easier to establish.

    4 HYDROGEN RECOVERY RATIO AND IMPURITY REMOVAL RATIO

    The hydrogen recovery ratio and impurity removal ratio for each impurity should be determined before performing hydrogen network integration, which depends on the characteristics of the used purification units.

    Normally, for the purification units mainly used to upgrade hydrogen concentration (for example, PSA and membrane), the hydrogen recovery ratio will be determined first, and the impurity removal ratios will be deduced accordingly. For the purification units mainly used to remove a kind of impurity, the removal ratio of the impurity will be determined first, and the hydrogen recovery ratio and the removal ratios of other impurities will be deduced accordingly.

    From industrial experiences, the following equations can be obtained for each kind of purification processes.

    4.1 PSA process without CO removal

    For a PSA process without CO removal, the hydrogen recovery ratio will be determined first. Not only H2S but also CO+CO2cannot be removed. Thus,

    where the subscript C means CO+CO2.

    Then, the concentrations of components H2S and CO+CO2in the product can be obtained as follows, respectively.

    It should be noted that the assumption for the product concentrations of components H2S [Eq. (4)] from Ref. [5] is not correct compared with Eq. (20) becausein a PAS process is not very close to 1.

    For other components, the removal ratio can be assumed as the same as follows.

    4.2 PSA process with CO removal

    For a PSA process with CO removal, the hydrogen recovery ratio and the removal ratio of CO+CO2will be determined first. It should be noted that rCis not zero and the product concentration of component CO+CO2is

    H2S still cannot be removed, whose removal ratio is also expressed with Eq. (18). For other components, the removal ratio can be also assumed as the same and can be calculated by Eq. (22).

    4.3 Membrane process

    In the membrane separation process, different components have different permeability, and thus the removal ratios for different components are also different. But normally, these components can be divided into two groups. The first group includes H2, H2S and CO2, which are termed as “fast gas” in industries. The another group has hydrocarbon components and CO, which are termed as “slow gas” in industries.

    As an approximation, it can be assumed that the removal ratios for the components termed as “fast gas” are the same and equal to the portion of unrecovered hydrogen as follows.

    The removal ratios for the components termed as“slow gas” are also the same and can be calculated by Eq (25).

    The hydrogen recovery ratio and the removal ratio of other impurities are listed below, respectively.

    where subscript HC means hydrocarbon.

    4.4 Desulfurization process

    For a desulfurization process, it can be considered that only H2S is removed. Although tiny CO2can be removed at the same time, it can be ignored. So the removal ratio for H2S,2HSr, is determined first. Then the product concentration of component H2S is

    Therefore, except H2S, the concentration of component i in the product stream, including H2, is almost identical during the process as follows.

    Figure 2 A superstructure for the hydrogen network with purification processes

    4.5 Light hydrocarbon recovery process

    The light hydrocarbon recovery process used in industries normally is an absorption process with gasoline a+nd diesel as the absorbents. The process recovers C3components and cannot remove other compo+nents. Therefore, the removal ratio of component C3, rC3+, is fixed first. The hydrogen recovery ratio is

    And the r+emoval ratios of other components except H2and C3are

    5 SUPERSTRUCTURE OF HYDROGEN NETWORKS BASED ON THE UNIFIED MODEL

    Based on the proposed unified model, a superstructure for the hydrogen network with purification processes can be constructed, as shown in Fig. 2. Each purification process in the superstructure is in a unified form no matter its function is to increase the hydrogen concentration or reduce some impurities’ concentrations.

    In the superstructure, each hydrogen source can supply stream not only to each hydrogen sink, but also to each purification process, as well as to the fuel system (not including the hydrogen utility). Each hydrogen sink can receive streams from not only each hydrogen source, but also each purification process. Each purification process can receive streams from hydrogen sources and other purification processes as its feed, supply its product stream and tail gas to hydrogen sinks and other purification processes, and can send the tail gas to the fuel system.

    REFERENCES

    1 Zhang, Q., Feng, X., Liu, G.L., “A novel graphical method for the integration of hydrogen distribution systems with purification reuse”, Chem. Eng. Sci., 66, 797-809 (2011).

    2 Zhou, L., Liao, Z.W., Wang, J.D., Jiang, B.B., Yang, Y.R., Hui, D.,“Optimal design of sustainable hydrogen networks”, Int. J. Hydrogen. Energ., 38, 2937-2950 (2013).

    3 Pacalowska, B., Whysall, M., Narasimhan M.V., “Improve hydrogen recovery from refinery offgases”, Hydrocarb. Process., 75, 55-59 (1996).

    4 Liu, F., Zhang, N., “Strategy of purifier selection and integration in hydrogen networks”, Chem. Eng. Res. Des., 82 (A10), 1315-1330 (2004).

    5 Zhou, L., Liao, Z.W., Wang, J.D., Jiang, B.B., Yang, Y.R., “Hydrogen sulfide removal process embedded optimization of hydrogen network”, Int. J. Hydrogen. Energ., 37, 18163-18174 (2012).

    6 Alves, J.J., Towler, G.P., “Analysis of refinery hydrogen distribution systems”, Ind. Eng. Chem. Res., 41, 5759-5769 (2002).

    7 El-Halwagi, M.M., Gabriel, F., Harell, D., “Rigorous graphical targeting for resource conservation via material recycle/reuse networks”, Ind. Eng. Chem. Res., 42, 4319-4328 (2003).

    8 Zhao, Z.H., Liu, G.L., Feng, X., “New graphical method for the integration of hydrogen distribution systems”, Ind. Eng. Chem. Res., 45, 6512-6517 (2006).

    9 Foo, D.C.Y., Manan, Z.A., “Setting the minimum utility gas flowrate targets using cascade analysis technique”, Ind. Eng. Chem. Res., 45, 5986-5995 (2006).

    10 Agrawal, V., Shenoy, U.V., “Unified conceptual approach to targeting and design of water and hydrogen networks”, AIChE J., 52, 1071-1082 (2006).

    11 Ng, D.K.S., Foo, D.C.Y., Tan, R.R., El-Halwagi, M., “Automatic targeting for concentration- and property-based total resource conservation network”, Comput. Chem. Eng., 34, 825-845 (2010).

    12 Liao, Z.W., Wang, J.D., Yang, Y.R., Rong, G., “Integrating purifiers in refinery hydrogen networks: a retrofit case study”, J. Clean. Prod., 18, 233-241 (2010).

    13 Liao, Z.W., Rong, G., Wang, J.D., Yang, Y.R., “Rigorous algorithmic targeting methods for hydrogen networks—Part II: Systems with one hydrogen purification unit”, Chem. Eng. Sci., 66, 821 (2011).

    14 Fonseca, A., Vitor, S., Bento, H., Tavares, M., Pinto, G., Gomes, L.,“Hydrogen distribution network optimization: a refinery case study”, J. Clean Prod., 16, 1755-1763 (2008).

    2013-08-20, accepted 2013-10-27.

    * Supported by the National Basic Research Program of China (2012CB720500) and the National Natural Science Foundation of China (21276204, 20936004).

    ** To whom correspondence should be addressed. E-mail: xfeng@cup.edu.cn

    国产精品无大码| 亚洲精品色激情综合| 在线观看三级黄色| 18禁在线无遮挡免费观看视频| 亚洲欧美日韩另类电影网站 | 欧美精品一区二区大全| 国产男女内射视频| 老司机影院成人| 建设人人有责人人尽责人人享有的 | 国产精品福利在线免费观看| 美女高潮的动态| 一级a做视频免费观看| 亚洲经典国产精华液单| 蜜桃久久精品国产亚洲av| 99热这里只有是精品在线观看| av女优亚洲男人天堂| 婷婷色综合www| 亚洲欧美一区二区三区国产| 午夜免费观看性视频| 欧美三级亚洲精品| 午夜激情久久久久久久| 水蜜桃什么品种好| 97超碰精品成人国产| 欧美精品人与动牲交sv欧美| 国产成人精品一,二区| 亚洲色图av天堂| 女人久久www免费人成看片| 国产色爽女视频免费观看| 欧美成人a在线观看| 激情 狠狠 欧美| 亚洲精品国产成人久久av| 伦理电影免费视频| 亚洲欧美日韩卡通动漫| 亚洲婷婷狠狠爱综合网| 麻豆成人午夜福利视频| 国产无遮挡羞羞视频在线观看| 高清在线视频一区二区三区| 亚洲成人av在线免费| 视频区图区小说| av国产精品久久久久影院| 亚洲av综合色区一区| 久久亚洲国产成人精品v| av网站免费在线观看视频| 国产成人精品婷婷| 最近的中文字幕免费完整| 日韩电影二区| 91久久精品电影网| 国产精品一区二区在线不卡| 国产一级毛片在线| 一个人看的www免费观看视频| 久久精品国产自在天天线| 国产黄片视频在线免费观看| 国产视频内射| 婷婷色综合www| 亚洲精品自拍成人| 最近中文字幕2019免费版| 成人一区二区视频在线观看| 狠狠精品人妻久久久久久综合| 超碰97精品在线观看| 最近的中文字幕免费完整| 国产日韩欧美在线精品| 1000部很黄的大片| 久久国产乱子免费精品| 精华霜和精华液先用哪个| 国内少妇人妻偷人精品xxx网站| 精品国产露脸久久av麻豆| 成人毛片a级毛片在线播放| 只有这里有精品99| 国产精品av视频在线免费观看| 成人国产av品久久久| av.在线天堂| 久久99热这里只有精品18| 亚洲婷婷狠狠爱综合网| 日韩电影二区| 深夜a级毛片| 国产精品女同一区二区软件| 啦啦啦啦在线视频资源| 亚洲成色77777| 七月丁香在线播放| 国产成人aa在线观看| 赤兔流量卡办理| 亚洲精品亚洲一区二区| 成人18禁高潮啪啪吃奶动态图 | 男女国产视频网站| 亚洲精品456在线播放app| 日韩,欧美,国产一区二区三区| 亚洲成人中文字幕在线播放| 女人十人毛片免费观看3o分钟| 亚洲精品乱码久久久v下载方式| h日本视频在线播放| 亚洲伊人久久精品综合| 久久久久精品性色| 亚洲久久久国产精品| 最黄视频免费看| 91精品伊人久久大香线蕉| 亚洲av在线观看美女高潮| 人体艺术视频欧美日本| 一级片'在线观看视频| 国产精品一区www在线观看| 免费看不卡的av| 日日啪夜夜撸| 91精品国产国语对白视频| 老熟女久久久| 1000部很黄的大片| 天美传媒精品一区二区| 老师上课跳d突然被开到最大视频| 国产高清不卡午夜福利| 国产亚洲午夜精品一区二区久久| 最近2019中文字幕mv第一页| 久久久久久久大尺度免费视频| 国产精品国产av在线观看| 免费观看av网站的网址| 97在线视频观看| av国产精品久久久久影院| 国产视频内射| 欧美+日韩+精品| 波野结衣二区三区在线| 亚洲欧洲国产日韩| 成人无遮挡网站| 国产精品麻豆人妻色哟哟久久| 欧美xxⅹ黑人| 久久久久人妻精品一区果冻| 国产欧美日韩一区二区三区在线 | 亚洲精品一二三| av播播在线观看一区| 91在线精品国自产拍蜜月| 亚洲精品乱码久久久v下载方式| 一级毛片黄色毛片免费观看视频| 激情 狠狠 欧美| 国产一级毛片在线| 黄色日韩在线| 午夜激情久久久久久久| 国产精品蜜桃在线观看| 网址你懂的国产日韩在线| 十分钟在线观看高清视频www | 99热6这里只有精品| 99re6热这里在线精品视频| 一区二区av电影网| 国产精品久久久久久精品电影小说 | 亚洲欧洲国产日韩| 大香蕉97超碰在线| 国产成人一区二区在线| 免费黄色在线免费观看| 日韩一区二区视频免费看| 亚洲精品久久久久久婷婷小说| 丰满乱子伦码专区| 国产深夜福利视频在线观看| 91久久精品电影网| 欧美日韩视频高清一区二区三区二| 99热这里只有精品一区| 久久久久久九九精品二区国产| 偷拍熟女少妇极品色| 亚洲美女搞黄在线观看| 久久久亚洲精品成人影院| 免费大片18禁| 99热这里只有是精品50| 国产真实伦视频高清在线观看| 美女内射精品一级片tv| kizo精华| 最近最新中文字幕免费大全7| 亚洲国产色片| 99re6热这里在线精品视频| 久久99热这里只有精品18| 中文乱码字字幕精品一区二区三区| 国产成人午夜福利电影在线观看| 国产成人91sexporn| 国产精品久久久久久精品电影小说 | 七月丁香在线播放| 亚洲成人一二三区av| 夫妻性生交免费视频一级片| 国产精品一区二区在线不卡| 最近最新中文字幕大全电影3| 日韩一本色道免费dvd| 丰满迷人的少妇在线观看| 亚洲人成网站在线播| 永久网站在线| 在线观看国产h片| av线在线观看网站| 午夜福利在线在线| 中文字幕精品免费在线观看视频 | 亚洲aⅴ乱码一区二区在线播放| 新久久久久国产一级毛片| 男的添女的下面高潮视频| 视频中文字幕在线观看| 久久久a久久爽久久v久久| 男女边摸边吃奶| 啦啦啦视频在线资源免费观看| 新久久久久国产一级毛片| 女性生殖器流出的白浆| 男的添女的下面高潮视频| 一区二区三区精品91| 高清日韩中文字幕在线| 亚洲av电影在线观看一区二区三区| 国产成人aa在线观看| 免费人成在线观看视频色| 亚洲欧美精品自产自拍| 久久久久久久久大av| 六月丁香七月| 欧美高清性xxxxhd video| 伦理电影大哥的女人| 黄片wwwwww| 久久精品久久精品一区二区三区| 天堂俺去俺来也www色官网| 亚洲人成网站在线观看播放| 22中文网久久字幕| 有码 亚洲区| 97精品久久久久久久久久精品| 亚洲av在线观看美女高潮| 日韩av不卡免费在线播放| 国产免费视频播放在线视频| 少妇的逼水好多| 日韩伦理黄色片| 成年人午夜在线观看视频| 在线精品无人区一区二区三 | 国产精品国产av在线观看| 一区二区av电影网| 亚洲精品中文字幕在线视频 | 汤姆久久久久久久影院中文字幕| 99久久精品国产国产毛片| 日日摸夜夜添夜夜添av毛片| 国产亚洲欧美精品永久| 欧美极品一区二区三区四区| 在线观看免费日韩欧美大片 | 免费观看性生交大片5| 欧美97在线视频| av免费观看日本| 久久久色成人| 欧美最新免费一区二区三区| 少妇裸体淫交视频免费看高清| 观看免费一级毛片| 成人国产麻豆网| 少妇人妻精品综合一区二区| 精品熟女少妇av免费看| 久久 成人 亚洲| av专区在线播放| 国产伦精品一区二区三区视频9| 精品人妻熟女av久视频| 亚洲国产高清在线一区二区三| 欧美性感艳星| 久久久精品免费免费高清| 久久久成人免费电影| 午夜激情福利司机影院| 永久免费av网站大全| 少妇猛男粗大的猛烈进出视频| 欧美变态另类bdsm刘玥| 中国三级夫妇交换| 精品99又大又爽又粗少妇毛片| 国产永久视频网站| 亚洲av免费高清在线观看| 日韩国内少妇激情av| 亚洲一级一片aⅴ在线观看| 精品一区在线观看国产| a 毛片基地| 日韩一区二区视频免费看| 亚洲av国产av综合av卡| 亚洲国产精品一区三区| 欧美丝袜亚洲另类| 中文资源天堂在线| 免费人妻精品一区二区三区视频| 超碰av人人做人人爽久久| 亚洲av综合色区一区| 看十八女毛片水多多多| 日韩精品有码人妻一区| 久久韩国三级中文字幕| videos熟女内射| 国产乱人视频| 亚洲精品日本国产第一区| 国产成人精品福利久久| 午夜免费鲁丝| 97超碰精品成人国产| av又黄又爽大尺度在线免费看| 国产视频内射| 久久鲁丝午夜福利片| 五月伊人婷婷丁香| 久久6这里有精品| 日日啪夜夜爽| 久久人妻熟女aⅴ| 有码 亚洲区| 色视频www国产| 黄色一级大片看看| 日日撸夜夜添| 久久久久网色| 97超碰精品成人国产| 美女主播在线视频| av在线播放精品| 亚洲精品乱码久久久v下载方式| 美女脱内裤让男人舔精品视频| 七月丁香在线播放| 精品一区二区三区视频在线| 80岁老熟妇乱子伦牲交| 自拍偷自拍亚洲精品老妇| av在线播放精品| 精品亚洲成国产av| 午夜福利高清视频| 丰满迷人的少妇在线观看| 久久久久久久大尺度免费视频| 熟女电影av网| 免费av中文字幕在线| 男人狂女人下面高潮的视频| 亚洲经典国产精华液单| 在线观看三级黄色| 99热全是精品| h日本视频在线播放| 十分钟在线观看高清视频www | 大片电影免费在线观看免费| 免费黄色在线免费观看| 夫妻性生交免费视频一级片| 色哟哟·www| 久久99热6这里只有精品| 国产伦在线观看视频一区| 26uuu在线亚洲综合色| 一本久久精品| 赤兔流量卡办理| 国产一区二区在线观看日韩| 一区二区三区免费毛片| 久久精品熟女亚洲av麻豆精品| 国产黄频视频在线观看| 人妻少妇偷人精品九色| 夫妻性生交免费视频一级片| 国产免费一区二区三区四区乱码| 久久久久久久久久成人| 91午夜精品亚洲一区二区三区| 久久久久视频综合| 老司机影院成人| 国产在线男女| 精品久久久久久久久亚洲| 日本一二三区视频观看| 午夜免费男女啪啪视频观看| 黄片wwwwww| 日本欧美国产在线视频| 另类亚洲欧美激情| 午夜日本视频在线| 九九久久精品国产亚洲av麻豆| 国精品久久久久久国模美| 国产久久久一区二区三区| 成人亚洲精品一区在线观看 | 亚洲欧美清纯卡通| 国产在线男女| 少妇人妻久久综合中文| 免费黄色在线免费观看| 男女啪啪激烈高潮av片| 少妇人妻精品综合一区二区| 日产精品乱码卡一卡2卡三| 狂野欧美激情性bbbbbb| 婷婷色麻豆天堂久久| 国产人妻一区二区三区在| 亚洲欧美精品自产自拍| 国产片特级美女逼逼视频| 成年美女黄网站色视频大全免费 | 精品少妇久久久久久888优播| 尾随美女入室| 色视频在线一区二区三区| 亚洲欧美成人精品一区二区| 在线观看国产h片| 国产精品人妻久久久久久| 欧美少妇被猛烈插入视频| 午夜免费观看性视频| 有码 亚洲区| 久久婷婷青草| 亚洲欧洲日产国产| 国产精品国产av在线观看| 欧美国产精品一级二级三级 | 亚洲精品亚洲一区二区| 99热这里只有是精品在线观看| 久久久午夜欧美精品| 国产中年淑女户外野战色| 亚洲av中文av极速乱| 在线免费观看不下载黄p国产| 亚洲av欧美aⅴ国产| 精品一区二区三区视频在线| 日韩av不卡免费在线播放| 欧美xxxx性猛交bbbb| 久久久亚洲精品成人影院| 亚洲人与动物交配视频| 免费人妻精品一区二区三区视频| 国产一级毛片在线| 精品国产三级普通话版| 中文在线观看免费www的网站| 国产精品一及| 久久国产精品男人的天堂亚洲 | 国产毛片在线视频| 啦啦啦中文免费视频观看日本| 内射极品少妇av片p| 欧美日韩视频高清一区二区三区二| 国产伦在线观看视频一区| 午夜免费鲁丝| 看免费成人av毛片| av国产久精品久网站免费入址| 黄色日韩在线| 2021少妇久久久久久久久久久| 永久网站在线| 狂野欧美激情性bbbbbb| 亚洲欧美精品专区久久| 如何舔出高潮| 亚洲av成人精品一二三区| 久久精品国产鲁丝片午夜精品| 日本vs欧美在线观看视频 | 肉色欧美久久久久久久蜜桃| 亚洲国产色片| 国产精品国产三级专区第一集| 韩国高清视频一区二区三区| 欧美bdsm另类| 新久久久久国产一级毛片| 亚洲精品乱久久久久久| 一级毛片aaaaaa免费看小| 欧美国产精品一级二级三级 | av在线观看视频网站免费| 国产视频内射| 在线观看一区二区三区| 老女人水多毛片| 爱豆传媒免费全集在线观看| 精品久久久噜噜| 成人国产麻豆网| 干丝袜人妻中文字幕| 亚洲精品日韩在线中文字幕| 我要看黄色一级片免费的| 国产乱来视频区| 国产美女午夜福利| 精品酒店卫生间| 亚洲欧美成人综合另类久久久| 亚洲精品国产av成人精品| 欧美激情极品国产一区二区三区 | 免费久久久久久久精品成人欧美视频 | 汤姆久久久久久久影院中文字幕| 久久国产亚洲av麻豆专区| 国产伦精品一区二区三区四那| 高清日韩中文字幕在线| 亚洲国产成人一精品久久久| 国产免费一级a男人的天堂| 国语对白做爰xxxⅹ性视频网站| 色5月婷婷丁香| 国产国拍精品亚洲av在线观看| 亚洲成人一二三区av| 国产乱人视频| 插阴视频在线观看视频| 欧美xxxx黑人xx丫x性爽| 99热这里只有是精品50| 3wmmmm亚洲av在线观看| 中文乱码字字幕精品一区二区三区| 日本黄色日本黄色录像| 丰满人妻一区二区三区视频av| 少妇 在线观看| 久久久久久久久久久免费av| 男女国产视频网站| 国产免费又黄又爽又色| 国产精品秋霞免费鲁丝片| 麻豆精品久久久久久蜜桃| 欧美精品一区二区大全| 毛片女人毛片| 欧美激情国产日韩精品一区| 超碰av人人做人人爽久久| 日本黄色日本黄色录像| 欧美日韩视频高清一区二区三区二| 日韩视频在线欧美| 国产精品av视频在线免费观看| 国产精品伦人一区二区| 国产乱人视频| 最后的刺客免费高清国语| 国产精品.久久久| 色视频在线一区二区三区| 80岁老熟妇乱子伦牲交| 国产精品人妻久久久影院| av在线app专区| 亚洲怡红院男人天堂| 晚上一个人看的免费电影| 日韩av在线免费看完整版不卡| 久久国内精品自在自线图片| 亚洲经典国产精华液单| 午夜福利视频精品| 午夜福利在线观看免费完整高清在| 国产美女午夜福利| 国产一区二区在线观看日韩| 一级爰片在线观看| 成人18禁高潮啪啪吃奶动态图 | 精品一区二区三区视频在线| 亚洲国产高清在线一区二区三| 欧美xxxx黑人xx丫x性爽| 亚洲欧美日韩东京热| 丰满迷人的少妇在线观看| www.av在线官网国产| 夜夜骑夜夜射夜夜干| 日本-黄色视频高清免费观看| 欧美xxxx黑人xx丫x性爽| 成年免费大片在线观看| 国产毛片在线视频| 国产亚洲欧美精品永久| videos熟女内射| 精品久久久久久电影网| 99热6这里只有精品| 国产精品久久久久久久电影| 男男h啪啪无遮挡| 亚洲久久久国产精品| 黑人猛操日本美女一级片| 黄色欧美视频在线观看| 高清日韩中文字幕在线| 亚洲精品乱码久久久v下载方式| av国产免费在线观看| 成人二区视频| 午夜福利在线在线| 亚洲精品成人av观看孕妇| 久久久亚洲精品成人影院| 欧美 日韩 精品 国产| 高清日韩中文字幕在线| 亚洲精华国产精华液的使用体验| 男男h啪啪无遮挡| 边亲边吃奶的免费视频| 91精品国产九色| 各种免费的搞黄视频| 熟女av电影| videossex国产| 久久精品人妻少妇| 成年av动漫网址| 国产亚洲欧美精品永久| 亚洲国产日韩一区二区| 久久久久网色| 美女主播在线视频| 美女中出高潮动态图| 人人妻人人添人人爽欧美一区卜 | 日韩大片免费观看网站| 熟女av电影| 能在线免费看毛片的网站| 男人舔奶头视频| 熟妇人妻不卡中文字幕| 男女边吃奶边做爰视频| 女性生殖器流出的白浆| 日韩 亚洲 欧美在线| 精品国产乱码久久久久久小说| 欧美97在线视频| 国产黄片视频在线免费观看| 精品熟女少妇av免费看| 国产精品伦人一区二区| 中文精品一卡2卡3卡4更新| 91狼人影院| 最近手机中文字幕大全| 自拍偷自拍亚洲精品老妇| 新久久久久国产一级毛片| 激情 狠狠 欧美| 精品国产一区二区三区久久久樱花 | 久久久久久久亚洲中文字幕| 少妇裸体淫交视频免费看高清| av.在线天堂| 欧美3d第一页| 亚洲国产欧美在线一区| 久久久久国产网址| 日韩亚洲欧美综合| 精品人妻视频免费看| 欧美一级a爱片免费观看看| 久久青草综合色| 欧美区成人在线视频| 国产精品嫩草影院av在线观看| 久久久久久九九精品二区国产| 国产91av在线免费观看| 国产精品三级大全| av天堂中文字幕网| 国产精品一二三区在线看| 色吧在线观看| 内射极品少妇av片p| 成年人午夜在线观看视频| 在线观看一区二区三区| 欧美变态另类bdsm刘玥| 能在线免费看毛片的网站| 国产精品成人在线| 国产精品麻豆人妻色哟哟久久| 精品少妇久久久久久888优播| 纵有疾风起免费观看全集完整版| 中文字幕亚洲精品专区| 国国产精品蜜臀av免费| 久久久久久久久久人人人人人人| 久久精品国产亚洲网站| 亚州av有码| 人妻制服诱惑在线中文字幕| 日韩 亚洲 欧美在线| 色婷婷av一区二区三区视频| 国产毛片在线视频| 女性被躁到高潮视频| 久久久久精品久久久久真实原创| 人人妻人人看人人澡| 婷婷色综合www| 日本色播在线视频| av专区在线播放| 成人无遮挡网站| 欧美日韩在线观看h| 免费人成在线观看视频色| 大片免费播放器 马上看| 日产精品乱码卡一卡2卡三| 久久久久久久亚洲中文字幕| 亚洲色图综合在线观看| 日韩av在线免费看完整版不卡| 国产大屁股一区二区在线视频| 日本av手机在线免费观看| 成人毛片a级毛片在线播放| 亚洲国产精品国产精品| 综合色丁香网| 国内少妇人妻偷人精品xxx网站| 又爽又黄a免费视频| 免费大片18禁| 欧美精品一区二区大全| av在线app专区| 免费观看性生交大片5| 久久精品人妻少妇| 亚洲国产毛片av蜜桃av| av在线播放精品| 日日啪夜夜撸| 成人美女网站在线观看视频| 男男h啪啪无遮挡| 免费人妻精品一区二区三区视频| 欧美97在线视频| 国产免费一区二区三区四区乱码| 国产一区二区三区av在线| 日韩欧美一区视频在线观看 | 亚洲人成网站高清观看| 日日摸夜夜添夜夜爱| 亚洲真实伦在线观看| 日韩电影二区| 性色avwww在线观看|