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页岩油较原油一般具有较高的杂原子含量，特别是较高的N含量，妨碍页岩油进入石化炼油体系进行深加工。本论文运用页岩油加氢提质过程对页岩油进行品质升级，经过加氢处理，页岩油可以达到甚至超过原油品质。其中，一定工艺条件下加氢页岩油N含量低于0.44 wt.%（胜利原油N含量）。基于此，本论文开展了页岩油加氢提质研究工作。本论文主要研究成果：1）页岩油及其加氢油的化合物物种分析。经过APPI+ FT-ICR质谱分析，桦甸-抚顺炉油（FHO）及其加氢油（HFHO-NiMo、HFHO-NiW和HFHO-CoMo）均含超20 000个质谱峰，所含化合物较复杂。在FHO中，N1和N1O1物种为主要氮化物，检测到的其他氮物种还有N1O2、N2、N1S1、N1O1S1和N1O3。S1物种为主要硫化物，S2物种含量很少，主要AHC物种是单双环芳烃物种。经加氢处理，页岩油中硫氮化合物脱除明显，其中NiMo催化剂表现出最佳HDS和HDN活性。在HFHO-NiMo、HFHO-NiW和HFHO-CoMo中，主要氮化物仍是N1物种，其它N物种含量非常少。所含N1物种主要为吲哚、咔唑和吖啶以及它们的衍生物。S1物种含量很低，基本不含S2物种。单双环AHC物种相对丰度仍然较高，特别是单环AHC物种。由于页岩油含有较高相对丰度的N1、N1O1物种，N1与N1O1物种间的转化有助于深入理解页岩油HDN反应。而N1、N1O1、S1物种向AHC物种的转化，导致加氢页岩油AHC物种相对丰度增加。2）页岩油加氢提质工艺条件考察和动力学模型。氢油体积比、体积空速、反应温度和反应压力对桦甸-抚顺炉油加氢尾气中C1-C4组成影响较小，且所得加氢油收率>99 wt.%。增加氢油体积比、降低体积空速、提高反应温度和反应压力有利于HDS、HDN反应进行，其中对HDN促进作用相对较大。桦甸-抚顺炉油加氢提质过程最佳氢油体积比可以取600 Nm3/m3。当反应条件为350 °C、8.0 MPa、600 Nm3/m3、1.0 h-1时，桦甸加氢-抚顺炉油S、N含量分别为0.021 wt.%和0.39 wt.%，低于胜利原油S、N含量。桦甸-抚顺炉油、桦甸-内构件炉油和龙口-抚顺炉油加氢尾气组成没有明显区别，且加氢油收率>99 wt.%。三种加氢页岩油中N含量均大于S含量，HDN转化率小于HDS，而HDS转化率差别较小。龙口-抚顺炉油所含N含量最多，而HDN转化率又最大，说明龙口-抚顺炉油含有较多易发生HDN反应的氮化物。每一温度条件下，桦甸-抚顺炉油和桦甸-内构件炉油具有几乎相同的HDS、HDN转化率，说明两者硫氮化合物类型基本类似。以工艺试验数据为基础，建立和验证了页岩油HDS、HDN反应宏观动力学模型。所建页岩油HDS动力学模型氢分压指数（0.24）小于HDN动力学模型氢分压指数（1.01），故页岩油HDN反应较HDS受压力影响大。同时页岩油HDN反应活化能（117.55 kJ/mol）高于HDS反应活化能（43.84 kJ/mol），因此页岩油HDN反应较HDS反应困难且受温度影响大。3）页岩油工业加氢催化剂稳定性试验。在装置运转30天内，桦甸-抚顺炉油加氢尾气中C1-C4组成受装置运转时间影响较小，且加氢油收率>99 wt.%。HDS转化率超过95 %，且下降非常小，因此HDS活性较为稳定。而HDN初始转化率超过90 %，在2～5天内HDN转化率出现下降，6～30天HDN转化率稳定在85 %附近，此时HDN活性较为稳定。上面情况主要是由催化剂积炭造成的。在反应初始阶段催化剂初始活性较高，引起含氮杂环芳烃化合物大量吸附在催化剂表面，造成积炭迅速增加；在反应稳定期积炭量变化很小，催化剂活性也趋于稳定。由于HDN反应存在先芳环加氢再氢解脱氮反应途径，故此过程对HDN反应影响较HDS明显。另外，不同位置催化剂发生加氢反应程度不同，尤其距反应器进口较远位置催化剂所接触物料杂原子含量较低，相应积炭量也较低。4）页岩油加氢催化剂载体性质、活性组分以及助剂改性研究。介孔氧化铝Al-P0.3-600较Al-LNHT、Al-RIPP具有高的表面结构性质，而由Al-P0.3-600作载体制备所得催化剂Ni-Mo/Al-P0.3-600也较其他两种催化剂（NiMo/Al-LNHT和NiMo/Al-RIPP）具有最大的比表面积和孔体积。同时NiMo/Al-LNHT催化剂页岩油加氢活性稍弱于NiMo/Al-P0.3-600催化剂，NiMo/Al-RIPP催化剂活性最弱。页岩油加氢催化剂孔径可以控制在6~10 nm之间。NiMo/Al2O3催化剂对桦甸-抚顺炉油的HDS和HDN性能优于NiW/Al2O3和CoMo/Al2O3催化剂，可以优选NiMo作为页岩油加氢催化剂活性组分。与NiMo/Al2O3、NiMo/Al2O3-SiO2-p催化剂及其硫化剂相比，纳米SiO2分散液改性NiMo/Al2O3-SiO2-d催化剂及其硫化剂具有高S含量、高表面Mo硫化度和低积炭量，较低的高低温H2还原温度，较多弱酸位和中等强度酸位，以及较少的强酸性位，还具有较小的且分散度较高的MoO3晶相。在评价催化剂时关闭反应釜出口阀，改性催化剂HDN活性较NiMo/Al2O3明显提高，而催化剂HDS活性变化规律相反。这主要是因为具有高N含量的桦甸-抚顺炉油随着HDN反应进行产生的大量NH3无法排出反应系统，从而抑制了HDS反应进行，并且随反应温度增加，这种抑制作用增强。其中，纳米SiO2分散液改性催化剂NiMo/Al2O3-SiO2-d的HDN活性最高。5）10万吨/年页岩油加氢提质反应器模型和反应器设计。以动力学模型为基础可以建立页岩油加氢提质反应器模型。通过反应器模型研究发现，不设急冷区时，页岩油加氢反应器温升约为90 °C；急冷区注入冷氢时，页岩油HDS和HDN效率高，加氢页岩油中S、N含量以及气相中H2S、NH3气体分压也较注冷页岩油时低；急冷区注入冷页岩油时，催化剂床层页岩油处理量以及脱硫脱氮量增加，同时提高了催化剂床层的利用率，对延长工业装置运转周期十分有利。利用反应器模型进行反应器设计相关计算，以及通过对催化剂装量、反应器直径和催化剂床层高度、急冷条件、反应器压力降的计算，得出了10万吨/年页岩油加氢提质反应器设计数据和基本结构。6）10万吨/年页岩油加氢提质工艺流程模拟。自定义反应器模块对模拟页岩油中硫氮脱除效率非常重要，且低压分离器中水相对反应产物中氮化物具有部分吸收作用。在产品物流中注水对分离吸收气相物流中H2S和NH3具有重要作用；提高反应温度可以增强系统HDS、HDN能力，同时注水质量流率上下限相对增大；升高系统压力可以增强系统HDS、HDN能力，同时也提高了水对H2S和NH3吸收能力，使注水质量流率上下限相对减小，其中上限下降明显；胺洗塔对H2S的吸收能力与贫胺液中MDEA的摩尔量线性相关；10万吨/年页岩油加氢提质工艺操作参数，可以为工艺设计提供参考。;Shale oil contains higher heteroatoms than crude oil, and especially its high N content are detrimental to the further utilization of shale oil in the refinery. Shale oil can be upgraded by hydrotreatment, and the quality of hydrotreated shale oil is even better than that of crude oil. For example, the hydrotreated shale oil under certain conditions can contain lower N content than Shengli crude oil does. Consequently, the paper carried out studies on the hydrotreatment of shale oil for oil upgrading.The acquired main conclusions in this work are summarized below. 1. Analysis of compound species for virgin and hydrotreated shale oil. Fushun furnace-Huadian shale Oil (FHO) and their hydrotreated products (HFHO) shown by HFHO-NiMo, HFHO-NiW and HFHO-CoMo were characterized using positive-ion mode APPI FT-ICR MS. More than 20 000 peaks were detected in the obtained spectra. In FHO, N1 and N1O1 species are the dominant N compounds and the other N species include, for example, N1O2, N2, N1S1, N1O1S1 and N1O3. Of S compounds, the S1 species are the major type because there are very few S2 species. The primary aromatic hydrocarbon (AHC) species are mono- and double-ring aromatics. After hydrotreatment, both S and N compounds in FHO are effectively removed. The NiMo catalyst exhibits the best catalytic performance for HDS and HDN of shale oil. In hydrotreated shale oils, N1 species reduced but were still the dominant N compound, and all the other N species were very few. The primary N1 species are indole, carbazole, acridine and their derivatives. The content of S1 species is very low and that of S2 species is close to zero. AHC species of mono- and double-ring aromatics still have high relative abundance, especially the mono-ring aromatics. Because of the high relative abundances of N1 and N1O1 species, the transformation between both species enables a better understanding of HDN for shale oil. The relative abundances of AHC species are enhanced as a result of the transformation of N1, N1O1, and S1 species into AHC species via hydrotreatment.2. Process conditions and kinetic models for shale oil hydrotreatment. After hydrotreatment, the yield of hydrotreated shale oil is higher than 99 wt.%, and the C1-C4 composition in exhaust gas is little influenced by the H2/Oil volume ratio, liquid hourly space velocity (LHSV), temperature and pressure. The conditions of high H2/Oil volume ratio, high temperature and pressure, and low LHSV are beneficial to HDS and HDN, especially to HDN. The preferred H2/Oil volume ratio is 600 Nm3/m3 for the FHO hydrotreatment. And HFHO contains 0.021 wt.% S and 0.39 wt.% N under conditions of 350 °C, 8.0 MPa, 600 Nm3/m3 of H2/Oil volume ratio and an LHSV of 1.0 h-1. These data values are lower than those of Shengli crude oil. When hydrotreating FHO, IHO (Internal furnace-Huadian shale Oil) and FLO (Fushun furnace-Longkou shale Oil), the compositions of their exhaust gases little differred from each other, and the yields of hydrotreated shale oil were all higher than 99 wt.%. The realized HDS conversions differred little and were bigger than the HDN conversions. The FLO may have high content of active N compounds which is prone to HDN. It had thus the largest N content and meanwhile the highest HDN conversion. Both FHO and IHO may have similar contents of S and N species so that they have almost the same HDS and HDN conversions at every tested temperature. Based on the data from hydrotreatment tests, the HDS and HDN macro-kinetic models were developed. The HDS reaction index to H2 partial pressure is 0.24, lower than 1.01 for HDN. Thus, the HDN reaction was more influenced by H2 partial pressure than the HDS reactions did. Meanwhile, the HDN is more difficult and more seriously influenced by temperature in comparison with HDS. Thus, the HDN reaction had the higher activation energy of 117.55 kJ/mol than 43.84 kJ/mol for the HDS reaction. 3. Stability of industrial catalyst in shale oil hydrotreatment. During 30-day runtime, the C1-C4 compositions of exhaust gas little varied, and the yields of HFHO were above 99 wt.%. The HDS activity was stable because the HDS conversion was higher than 95 % and declined very little. The initial HDN conversion was above 90 %, and it continuously decreased in the first 5 days of running. Then, the HDN activity became stable and its conversion was about 85 % in 6 to 30 days of running. The variations of HDS and HDN performance with time may be caused by carbon deposition on catalyst. In the initial stage of reactions, the N-containing heterocyclic compounds largely adsorbed on the surface of catalyst having high initial activity so that the carbon deposition rose quickly. In turn, the carbon deposition varied very little to show the stable catalytic activity. Because N-containing heterocyclic compounds are hardly directly removed by hydrogenolysis but they adsorb firstly on the catalyst surface such that the carbon deposition inhibits more severely the HDN than HDS reactions. The performance of hydrotreatment also varied with the position of catalyst bed. The carbon deposition of catalyst bed near the reactor outlet is lower because the shale oil encountered there contains low content of S and N. 4. Reactor model and reactor design of 100 000 t/a shale oil hydrotreatment. A reactor model is established on the basis of HDS and HDN macro-kinetic models for shale oil hydrotreatmet. The reactor temperature rise is about 90 °C without a quench zone. When the inside of reactor is quenched using cold H2, the HDS and HDN conversions are higher, and the S and N contents in hydroytreated oil are lower in comparison with the case using cold shale oil as the cooling medium. When the reactor is quenched using shale oil, the device capacity and S&N removal efficiencies all increased. The enhanced utilization of catalyst bed will benefit the long-term running of the reactor. The reactor model provides parameters for reactor design, and we obtained the basic structure parameters of a hydrotreatment reactor at 100 000 t/a including the catalyst loading, reactor diameter, quench conditions, reactor pressure drop, etc.5. Process simulation of 100 000 t/a shale oil hydrotreatment. Water in Low Pressure Separator has certain absorption of N compounds, and water injection plays an important role in absorption of H2S and NH3 from gas flow. Both HDS and HDN can be enhanced by increasing temperature, meanwhile the upper and lower limits of injected water flow rate also increase. The increased system pressure can also enhance the HDS and HDN performances, and improve the absorption of H2S and NH3. These decrease the water flow rate limits, and especially the upper water flow limit showed obvious decrease. The H2S absorption in Amine Washing Tower linearly varies with MDEA content. The operational parameters obtained in process simulation is essential for engineering design. 6. Carrier, active component and promoter of catalyst. The carrier sample Al-P0.3-600 has better textural properties than the other two samples, Al-LNHT and Al-RIPP. Meanwhile, the NiMo/Al-P0.3-600 catalyst has the largest specific surface area and porous volume in comparison to the other two catalysts of NiMo/Al-LNHT and NiMo/Al-RIPP. NiMo/Al-LNHT has the slightly lower activity than NiMo/Al-P0.3-600 does, and the activity of NiMo/Al-RIPP is the lowest. For hydrotreatment of shale oil, the preferred pore size of catalyst is in the range of 6-10 nm. The NiMo is the preferred active component of catalyst because NiMo/Al2O3 showed the higher HDS and HDN activities than the other two catalysts NiW/Al2O3 and CoMo/Al2O3 did. In comparison with NiMo/Al2O3 and NiMoS/Al2O3-SiO2-p, the NiMo/Al2O3-SiO2-d modified with dispersed nano-SiO2 has the higher S content, higher Mo sulfidation degree, lower carbon deposition, lower low- and high-reduction temperatures, more weak- and mid-acid sites, less strong-acid sites, and more dispersed and smaller MoO3 particles. The catalyst NiMo/Al2O3-SiO2-d has the higher HDN and lower HDS activities than the other two catalysts do, as shown by evaluation tests in an autoclave with its outlet valve closed. The reason may be that the large amount of NH3 formed in HDN inhibited HDS. The inhibition becomes stronger with enhanced HDN activity or increased temperature.
|张奎. 页岩油加氢提质研究[D]. 中国科学院研究生院,2017.|
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