• <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

    av天堂中文字幕网| 成人高潮视频无遮挡免费网站| 韩国av一区二区三区四区| 成人欧美大片| 亚洲在线自拍视频| 性欧美人与动物交配| 在线看三级毛片| 在线观看美女被高潮喷水网站 | 亚洲美女视频黄频| 黄色成人免费大全| 波多野结衣巨乳人妻| 在线播放国产精品三级| 熟女人妻精品中文字幕| 亚洲国产精品成人综合色| 国产免费av片在线观看野外av| 午夜福利高清视频| av福利片在线观看| 好看av亚洲va欧美ⅴa在| 亚洲不卡免费看| 男插女下体视频免费在线播放| 日韩av在线大香蕉| 国产av不卡久久| 亚洲国产高清在线一区二区三| 中文在线观看免费www的网站| 国产欧美日韩一区二区精品| 制服丝袜大香蕉在线| 97人妻精品一区二区三区麻豆| 国产高清视频在线播放一区| 韩国av一区二区三区四区| 蜜桃亚洲精品一区二区三区| 青草久久国产| 丰满乱子伦码专区| 亚洲精品一区av在线观看| 久久国产精品影院| 夜夜躁狠狠躁天天躁| 日本黄色片子视频| av视频在线观看入口| 午夜福利免费观看在线| 亚洲欧美日韩无卡精品| 国产精品亚洲一级av第二区| 成人永久免费在线观看视频| 一级毛片高清免费大全| 欧美成人免费av一区二区三区| 男女视频在线观看网站免费| 成人特级av手机在线观看| 国产精品香港三级国产av潘金莲| 精品人妻偷拍中文字幕| 波野结衣二区三区在线 | 国产视频一区二区在线看| 午夜免费男女啪啪视频观看 | 一级毛片高清免费大全| 国产亚洲欧美98| 男人的好看免费观看在线视频| 90打野战视频偷拍视频| 91麻豆精品激情在线观看国产| 男女午夜视频在线观看| 精品一区二区三区视频在线观看免费| 精品不卡国产一区二区三区| 一级毛片高清免费大全| 一本精品99久久精品77| 色av中文字幕| 亚洲成人久久爱视频| 高清毛片免费观看视频网站| 亚洲av熟女| 欧美性感艳星| 免费av毛片视频| 村上凉子中文字幕在线| 手机成人av网站| netflix在线观看网站| 美女被艹到高潮喷水动态| av黄色大香蕉| 亚洲第一欧美日韩一区二区三区| 久久性视频一级片| 亚洲aⅴ乱码一区二区在线播放| 日本一二三区视频观看| 亚洲avbb在线观看| 色尼玛亚洲综合影院| 99热6这里只有精品| 日韩高清综合在线| 欧美在线一区亚洲| 日韩欧美免费精品| 国产精品日韩av在线免费观看| 亚洲av免费在线观看| 在线观看一区二区三区| 99国产极品粉嫩在线观看| 欧美日韩黄片免| 变态另类成人亚洲欧美熟女| 亚洲av二区三区四区| 国产熟女xx| 在线国产一区二区在线| 波多野结衣巨乳人妻| 国产激情偷乱视频一区二区| 一本精品99久久精品77| 欧美成人免费av一区二区三区| 一级黄片播放器| 一级作爱视频免费观看| 成人性生交大片免费视频hd| 精品无人区乱码1区二区| 色视频www国产| 无人区码免费观看不卡| 国产精品嫩草影院av在线观看 | 亚洲人与动物交配视频| 成人av在线播放网站| 一区二区三区免费毛片| 亚洲性夜色夜夜综合| 日韩欧美免费精品| 久久久久久大精品| 亚洲国产欧美人成| 亚洲av成人av| 国产欧美日韩精品亚洲av| 日韩欧美一区二区三区在线观看| 五月伊人婷婷丁香| 久久人人精品亚洲av| 男女午夜视频在线观看| 日韩欧美精品v在线| 女人高潮潮喷娇喘18禁视频| 亚洲自拍偷在线| 国产精品久久久久久亚洲av鲁大| 色哟哟哟哟哟哟| 两个人的视频大全免费| 亚洲成人免费电影在线观看| 亚洲人成网站在线播放欧美日韩| 欧美不卡视频在线免费观看| 国产亚洲精品一区二区www| 国产伦一二天堂av在线观看| 香蕉久久夜色| 国产熟女xx| 特级一级黄色大片| 免费无遮挡裸体视频| 亚洲成人免费电影在线观看| 国产亚洲精品久久久久久毛片| 欧美最新免费一区二区三区 | 午夜激情欧美在线| 成人无遮挡网站| 亚洲av第一区精品v没综合| 天美传媒精品一区二区| 免费观看人在逋| 精品免费久久久久久久清纯| 亚洲狠狠婷婷综合久久图片| 久久久久久国产a免费观看| 深夜精品福利| 九色成人免费人妻av| 手机成人av网站| 精品一区二区三区av网在线观看| 亚洲av成人精品一区久久| 99精品在免费线老司机午夜| 欧美最黄视频在线播放免费| 国产aⅴ精品一区二区三区波| 亚洲精品乱码久久久v下载方式 | 91av网一区二区| 中文字幕av成人在线电影| 97碰自拍视频| 一进一出抽搐gif免费好疼| 午夜福利高清视频| 国产爱豆传媒在线观看| 欧美区成人在线视频| 一区二区三区激情视频| 午夜两性在线视频| 身体一侧抽搐| 日韩人妻高清精品专区| 神马国产精品三级电影在线观看| 国产乱人视频| 一区二区三区激情视频| 日本免费一区二区三区高清不卡| 国产爱豆传媒在线观看| 日本五十路高清| 国产精品三级大全| 亚洲精品久久国产高清桃花| 淫妇啪啪啪对白视频| 伊人久久大香线蕉亚洲五| 免费观看人在逋| 国产精品 欧美亚洲| 999久久久精品免费观看国产| 国产一区二区亚洲精品在线观看| 精品无人区乱码1区二区| 老司机深夜福利视频在线观看| 久久这里只有精品中国| 国产成人影院久久av| 国产精品电影一区二区三区| 亚洲精品一区av在线观看| 91久久精品国产一区二区成人 | 国产一级毛片七仙女欲春2| 亚洲成人精品中文字幕电影| 午夜福利在线在线| 免费在线观看影片大全网站| 色av中文字幕| 国产蜜桃级精品一区二区三区| 黑人欧美特级aaaaaa片| 国产三级中文精品| 国产97色在线日韩免费| 国产男靠女视频免费网站| 亚洲欧美精品综合久久99| 一本一本综合久久| 综合色av麻豆| 久久久久久九九精品二区国产| 美女被艹到高潮喷水动态| 国产美女午夜福利| 超碰av人人做人人爽久久 | 波多野结衣高清无吗| 悠悠久久av| 99久久精品一区二区三区| 国产精品永久免费网站| 亚洲久久久久久中文字幕| 老司机午夜福利在线观看视频| 国产精品亚洲av一区麻豆| 女人被狂操c到高潮| 日韩欧美在线二视频| 国产av一区在线观看免费| 黑人欧美特级aaaaaa片| 日本一本二区三区精品| 中文字幕久久专区| 欧美乱码精品一区二区三区| 中文资源天堂在线| 内射极品少妇av片p| 免费av不卡在线播放| 特级一级黄色大片| 网址你懂的国产日韩在线| 又黄又爽又免费观看的视频| 欧美精品啪啪一区二区三区| 1000部很黄的大片| av天堂在线播放| 3wmmmm亚洲av在线观看| 亚洲av免费在线观看| 一个人免费在线观看的高清视频| 欧美zozozo另类| 欧美色视频一区免费| av片东京热男人的天堂| 日本在线视频免费播放| 亚洲第一电影网av| 日日夜夜操网爽| 搞女人的毛片| 国产视频一区二区在线看| 久久精品人妻少妇| 啦啦啦免费观看视频1| 他把我摸到了高潮在线观看| 长腿黑丝高跟| 日本a在线网址| 嫁个100分男人电影在线观看| 久久久久性生活片| 欧美另类亚洲清纯唯美| 两个人看的免费小视频| 成人精品一区二区免费| 免费在线观看日本一区| 最新在线观看一区二区三区| 男人的好看免费观看在线视频| 俄罗斯特黄特色一大片| 麻豆国产97在线/欧美| 欧美在线一区亚洲| 一进一出好大好爽视频| 日韩免费av在线播放| 国产精品1区2区在线观看.| 免费一级毛片在线播放高清视频| 欧美极品一区二区三区四区| 99精品久久久久人妻精品| 一个人免费在线观看电影| 午夜福利在线观看吧| 在线免费观看不下载黄p国产 | 国产乱人视频| 国产高清激情床上av| 亚洲av日韩精品久久久久久密| 欧美成人性av电影在线观看| 麻豆成人午夜福利视频| 亚洲avbb在线观看| 99热精品在线国产| av福利片在线观看| 久久久久久人人人人人| 久久精品夜夜夜夜夜久久蜜豆| 日本 欧美在线| 日本三级黄在线观看| 成年版毛片免费区| 日本免费一区二区三区高清不卡| 丰满的人妻完整版| 免费看美女性在线毛片视频| 美女cb高潮喷水在线观看| 99久久精品国产亚洲精品| 老司机福利观看| 国产亚洲精品一区二区www| 12—13女人毛片做爰片一| 香蕉av资源在线| 国产伦人伦偷精品视频| 国产精品嫩草影院av在线观看 | 国产成+人综合+亚洲专区| 久久久久久九九精品二区国产| 搡女人真爽免费视频火全软件 | 人妻夜夜爽99麻豆av| 久久精品国产亚洲av香蕉五月| 欧美性感艳星| 三级毛片av免费| 啦啦啦韩国在线观看视频| 国产精品亚洲一级av第二区| 日韩 欧美 亚洲 中文字幕| 淫秽高清视频在线观看| 一本一本综合久久| 亚洲天堂国产精品一区在线| 熟妇人妻久久中文字幕3abv| 欧美三级亚洲精品| 国产私拍福利视频在线观看| 成人午夜高清在线视频| e午夜精品久久久久久久| xxx96com| 九九在线视频观看精品| av国产免费在线观看| 国产精品女同一区二区软件 | 国产一区二区三区视频了| 国产真人三级小视频在线观看| 床上黄色一级片| 欧美成狂野欧美在线观看| 欧美日韩亚洲国产一区二区在线观看| 亚洲中文日韩欧美视频| 亚洲中文字幕一区二区三区有码在线看| avwww免费| 成人午夜高清在线视频| 首页视频小说图片口味搜索| 国产av麻豆久久久久久久| h日本视频在线播放| 精品人妻1区二区| 亚洲精品国产精品久久久不卡| 男女之事视频高清在线观看| 国产中年淑女户外野战色| 国产高清videossex| 在线十欧美十亚洲十日本专区| 中文字幕av成人在线电影| 亚洲熟妇中文字幕五十中出| 日韩高清综合在线| 色综合欧美亚洲国产小说| 午夜日韩欧美国产| 久久久久久九九精品二区国产| 日韩欧美三级三区| 一区二区三区免费毛片| 性欧美人与动物交配| 99热精品在线国产| 全区人妻精品视频| 免费av毛片视频| www.www免费av| 国产高清videossex| 亚洲最大成人中文| 国产伦精品一区二区三区视频9 | 可以在线观看的亚洲视频| 日韩大尺度精品在线看网址| 亚洲专区国产一区二区| 日本 av在线| 免费人成视频x8x8入口观看| 欧美黄色淫秽网站| 91在线观看av| 国产av在哪里看| 极品教师在线免费播放| 亚洲人成伊人成综合网2020| 一区二区三区国产精品乱码| 日本免费一区二区三区高清不卡| 免费在线观看亚洲国产| 观看免费一级毛片| 国产毛片a区久久久久| 丁香欧美五月| 亚洲av第一区精品v没综合| 国产单亲对白刺激| 国产免费男女视频| 成人三级黄色视频| 搡老妇女老女人老熟妇| av片东京热男人的天堂| netflix在线观看网站| 12—13女人毛片做爰片一| 久久精品影院6| 成人性生交大片免费视频hd| 脱女人内裤的视频| 1000部很黄的大片| 亚洲熟妇中文字幕五十中出| 亚洲五月婷婷丁香| 九色国产91popny在线| 久久精品人妻少妇| 精品久久久久久久毛片微露脸| 首页视频小说图片口味搜索| 亚洲国产精品合色在线| 国产精品香港三级国产av潘金莲| 成人无遮挡网站| 午夜精品一区二区三区免费看| 亚洲精品亚洲一区二区| 在线观看美女被高潮喷水网站 | 18禁在线播放成人免费| 91麻豆av在线| 国产精品1区2区在线观看.| 精品国产美女av久久久久小说| 亚洲成av人片免费观看| 看黄色毛片网站| 亚洲精品日韩av片在线观看 | 国产高清videossex| 国产高清视频在线播放一区| 亚洲熟妇熟女久久| 老司机午夜十八禁免费视频| 国产精品乱码一区二三区的特点| 亚洲美女视频黄频| 亚洲成av人片免费观看| 日日摸夜夜添夜夜添小说| 久久国产乱子伦精品免费另类| 国产高清有码在线观看视频| 日本三级黄在线观看| 动漫黄色视频在线观看| 亚洲无线在线观看| 久久精品国产99精品国产亚洲性色| 国产精品99久久久久久久久| 国产精品久久久人人做人人爽| 一本一本综合久久| 18+在线观看网站| 中文字幕人成人乱码亚洲影| 国产精品久久视频播放| 亚洲欧美日韩高清在线视频| 欧美av亚洲av综合av国产av| 老鸭窝网址在线观看| 精品国内亚洲2022精品成人| 欧美又色又爽又黄视频| 两个人视频免费观看高清| 丰满人妻熟妇乱又伦精品不卡| 久久精品91蜜桃| 99国产综合亚洲精品| 国产av一区在线观看免费| 两个人的视频大全免费| 少妇裸体淫交视频免费看高清| 欧美国产日韩亚洲一区| 久久久久久人人人人人| 国产伦人伦偷精品视频| 天堂影院成人在线观看| 日本免费一区二区三区高清不卡| 免费看美女性在线毛片视频| 欧美国产日韩亚洲一区| 91久久精品电影网| 亚洲无线在线观看| 亚洲av电影不卡..在线观看| 不卡一级毛片| 嫩草影院精品99| 日韩欧美在线二视频| 日韩人妻高清精品专区| or卡值多少钱| 天堂影院成人在线观看| 久久久久久九九精品二区国产| 男女之事视频高清在线观看| www.熟女人妻精品国产| 精品国产亚洲在线| 亚洲无线在线观看| 午夜福利成人在线免费观看| 免费在线观看影片大全网站| 久久香蕉国产精品| 蜜桃亚洲精品一区二区三区| 亚洲中文字幕日韩| 九色成人免费人妻av| 国产精品久久电影中文字幕| 欧美中文日本在线观看视频| 女人被狂操c到高潮| 两个人看的免费小视频| 夜夜夜夜夜久久久久| 国产av麻豆久久久久久久| 国产真人三级小视频在线观看| 黄片大片在线免费观看| 日韩欧美在线乱码| 国产伦精品一区二区三区视频9 | 少妇的丰满在线观看| 久久香蕉精品热| 偷拍熟女少妇极品色| 国产又黄又爽又无遮挡在线| 国产三级中文精品| 午夜老司机福利剧场| netflix在线观看网站| 最新中文字幕久久久久| 亚洲成人久久爱视频| 免费av不卡在线播放| 成人特级av手机在线观看| 欧美中文综合在线视频| av在线蜜桃| 亚洲国产精品成人综合色| 啦啦啦韩国在线观看视频| 欧美在线黄色| 在线观看免费午夜福利视频| 成年版毛片免费区| or卡值多少钱| 最近最新中文字幕大全电影3| 午夜免费成人在线视频| 日韩高清综合在线| 亚洲一区二区三区不卡视频| 久久久久久久久久黄片| 国产单亲对白刺激| 一二三四社区在线视频社区8| 成人鲁丝片一二三区免费| 老汉色∧v一级毛片| 51午夜福利影视在线观看| 国产精品野战在线观看| 国产精品久久久久久精品电影| 国产69精品久久久久777片| 国产高清视频在线播放一区| 啪啪无遮挡十八禁网站| 国产av麻豆久久久久久久| 国产精品av视频在线免费观看| 女警被强在线播放| 女同久久另类99精品国产91| 欧美日韩乱码在线| 日韩大尺度精品在线看网址| 婷婷六月久久综合丁香| 色视频www国产| 国产一区二区三区视频了| 最近最新中文字幕大全免费视频| 脱女人内裤的视频| 国产精品av视频在线免费观看| 97超级碰碰碰精品色视频在线观看| 久久精品91蜜桃| 亚洲av第一区精品v没综合| 99热精品在线国产| 久久这里只有精品中国| 免费在线观看成人毛片| 午夜福利在线观看免费完整高清在 | 亚洲av电影在线进入| 欧洲精品卡2卡3卡4卡5卡区| 此物有八面人人有两片| 久久久久九九精品影院| 亚洲国产精品合色在线| 久久久精品欧美日韩精品| 一级毛片女人18水好多| 一进一出好大好爽视频| 女人被狂操c到高潮| 精品电影一区二区在线| 青草久久国产| 午夜福利在线观看免费完整高清在 | 两人在一起打扑克的视频| 国产精品1区2区在线观看.| 欧美一区二区亚洲| 淫妇啪啪啪对白视频| 搡女人真爽免费视频火全软件 | 亚洲欧美日韩卡通动漫| 午夜免费男女啪啪视频观看 | 免费av毛片视频| 成人亚洲精品av一区二区| av中文乱码字幕在线| 99在线视频只有这里精品首页| 小说图片视频综合网站| 狠狠狠狠99中文字幕| 欧美日韩国产亚洲二区| 久久久久久久午夜电影| 日韩大尺度精品在线看网址| 国产精品一及| 国产久久久一区二区三区| 亚洲乱码一区二区免费版| 三级毛片av免费| 亚洲电影在线观看av| 免费搜索国产男女视频| 国产探花极品一区二区| 舔av片在线| 小蜜桃在线观看免费完整版高清| 18禁国产床啪视频网站| 亚洲精品456在线播放app | 美女被艹到高潮喷水动态| 亚洲美女黄片视频| 听说在线观看完整版免费高清| 久久久久久久久中文| 岛国在线免费视频观看| 熟女电影av网| 在线免费观看不下载黄p国产 | 国产精品永久免费网站| 床上黄色一级片| 国产免费男女视频| 精品久久久久久久末码| 动漫黄色视频在线观看| bbb黄色大片| 亚洲真实伦在线观看| 欧美成人免费av一区二区三区| 午夜免费观看网址| 一级毛片高清免费大全| 最近最新中文字幕大全免费视频| 午夜两性在线视频| 无人区码免费观看不卡| 国产精品香港三级国产av潘金莲| 亚洲人成网站高清观看| 黄色视频,在线免费观看| 精品福利观看| 亚洲欧美日韩高清专用| 免费看a级黄色片| 国产成人啪精品午夜网站| 亚洲18禁久久av| 一区二区三区国产精品乱码| 国产亚洲欧美在线一区二区| 欧美日本视频| 免费人成视频x8x8入口观看| 国内精品美女久久久久久| 夜夜夜夜夜久久久久| 国产精品av视频在线免费观看| 九色国产91popny在线| 精品久久久久久久毛片微露脸| 99久久九九国产精品国产免费| 男插女下体视频免费在线播放| 又粗又爽又猛毛片免费看| 91麻豆av在线| 波多野结衣高清作品| 国产成+人综合+亚洲专区| 高清毛片免费观看视频网站| 亚洲一区二区三区色噜噜| 欧美黄色淫秽网站| 日韩欧美一区二区三区在线观看| 国产伦精品一区二区三区四那| 成人午夜高清在线视频| 国产99白浆流出| 桃色一区二区三区在线观看| 国产蜜桃级精品一区二区三区| 欧美一级a爱片免费观看看| 综合色av麻豆| 婷婷亚洲欧美| 久久久色成人| 少妇人妻一区二区三区视频| 日本一本二区三区精品| 国产精品三级大全| 欧美乱色亚洲激情| 中亚洲国语对白在线视频| 我的老师免费观看完整版| 国产亚洲欧美98| 内地一区二区视频在线| 色在线成人网| 免费看日本二区| 色噜噜av男人的天堂激情| 亚洲国产精品久久男人天堂| 婷婷六月久久综合丁香| 两个人看的免费小视频|