【作者】 胡永庆；

【导师】 山红红；

【作者基本信息】 中国石油大学 ， 化学工程与技术， 2011， 博士

【摘要】 随着原油价格的不断上涨,原油加工成本越来越高,炼油企业的经济效益受到严重影响。高酸原油储量丰富,价格相对较低,可以使炼油企业获得更高的利润。然而,高酸原油是典型的劣质原油,具有高酸值、高密度、高粘度、高残炭、高金属含量等特点,在常规加工过程中不但会造成设备的严重腐蚀,而且由于轻馏分含量太少,蜡油、渣油馏分品质太差,给其有效加工带来挑战。采用催化裂化直接加工高酸原油,不仅可以有效避免设备的腐蚀,还可以优化产物分布,提高产品质量,缩短加工流程,节省加工成本。本论文对高酸原油直接催化裂化过程中的基础问题进行了研究。首先以工业提纯的环烷酸为反应物,在固定床微反装置上进行了热转化和催化转化实验。结果表明,环烷酸的热分解脱酸速率较慢,脱酸率较低,反应温度对脱酸率的影响显著。环烷酸的催化脱酸效果显著,催化剂类型对环烷酸脱酸率影响较小,但是脱酸产物明显不同。环烷酸在CORH、LTB-2两种分子筛催化剂上的脱酸率接近100%,且基本不受反应条件的影响,脱酸产物以CO为主;环烷酸在弱酸性γ-Al2O3、碱性MgO和CaO上的脱酸率略低,脱酸产物以CO2为主。虽然同为碱性氧化物,环烷酸在MgO上以催化脱酸为主,但是在CaO上还包括中和脱酸,反应过程中生成环烷酸钙。此外,烃类不会影响环烷酸的催化脱酸反应。分子模拟的结果表明,不同类型的环烷酸在B酸位的脱酸过程不同。羧基与环直接相连的环烷酸在B酸位的催化脱酸过程存在两种路径,以先开环后脱酸为主,产物主要是CO。羧基通过烷基链与环相连的环烷酸在分子筛B酸位的脱酸过程类似于正碳离子反应机理,羰基氧与质子接触后引起键级的变化,在β位发生断裂生成甲酸,然后分解为CO和H2O。环烷酸与碱性氮化物在分子筛孔道内的吸附能力不同,碱性氮化物与分子筛的结合能力更强。由于空间位阻效应,小分子化合物的吸附量更大。苏丹达尔高酸原油虽然品质很差,但是由于其重组分的强石蜡性质,催化裂化性能优良。在反应温度460℃、停留时间1.15s、剂油比6左右的缓和条件下,重油转化率达到90%以上,液收达到80%以上。液化气中丙烯和丁烯的含量超过80%,汽油中烯烃含量小于40%。由于原料的残炭大于8%,导致苏丹达尔原油直接催化裂化的焦炭产率较高。苏丹达尔原油直接催化裂化的工业试验验证了实验室的研究结果,并且得到了更好的产物分布。单程转化率非常高,不需要进行回炼油(浆)的回炼;高残炭导致了高的焦炭产率,从而使再生器的烧焦负荷大大增加;原料中直馏柴油的存在使高酸原油直接催化裂化的柴油品质高于普通的催化裂化柴油,而且酸度也合格。通过苏丹达尔高酸原油不同加工方案的经济性分析可知,直接催化裂化具有最好的产物分布,其产品总值比常减压—催化裂化—延迟焦化的常规加工方案和直接延迟焦化方案分别高355元/吨和513元/吨。虽然催化裂化的能耗要高于延迟焦化和常规加工方案,但直接催化裂化总毛利仍比常规加工方案和直接延迟焦化分别高317元/吨和315元/吨。如果考虑在常规加工方案和延迟焦化方案中需要添加的各种破乳剂、消泡剂、缓蚀剂等的成本以及人工成本在内,利润差将进一步增大。更多还原

【Abstract】 Along with increasing of crude oil’s price, cost of crude oil is getting higher and higher and refinery’s profit drops unceasingly. In the world, resources of high total acid number (TAN) crude oil are rich, and the price is lower than high quality crude oil. Refineries can obtain high profits if they processing high TAN crude oil. However, high TAN crude oil is the typical inferior crude oil with high TAN, high density, high viscosity, high carbon residue and high metal content. Processing high TAN crude oil can cause apparatus’serious corrosion. Moreover, content of light fraction is low and quality of VGO and VR is inferior in high TAN crude oil. These limit the processing of high TAN crude oil widely. Uses of FCC to process high TAN crude oil can not only avoid apparatus’corrosion, but also optimize product distribution, improve product quality, reduce processing line and save processing cost. So direct catalytic cracking of high TAN crude oil were studied in this paper.Firstly, thermal and catalytic conversion experiments of naphthenic acids were carried out in the fixed bed microreactor apparatus. The experimental results indicated that thermal decarboxylation rate was slow, and the decarboxylation ratio was low. Reaction temperature was the dominant influential factor of the thermal decarboxylation. Catalytic decarboxylation effect of naphthenic acids was remarkable. Influences of catalysts to catalytic decarboxylation ratio were indistinct. But catalytic decarboxylation products were different over various catalysts. Catalytic decarboxylation ratios of naphthenic acids over CORH and LTB-2 were 100% approximately. This ratio were not be affected by the reaction conditions, and CO was dominant catalytic decarboxylation product. Catalytic decarboxylation ratios of naphthenic acids overγ-Al2O3、MgO and CaO were lower slightly than that over CORH and LTB-2, and CO2 was dominant catalytic decarboxylation product. Although CaO and MgO are the basic oxides, decarboxylation mechanisms over these basic oxides are different. Catalytic decarboxylation was primary over MgO. Over CaO, there was not only catalytic decarboxylation, but also neutralization decarboxylation. The product of neutralization decarboxylation over CaO was calcium naphthenate. In addition, the straight running hydrocarbons can not affect the catalytic decarboxylation of naphthenic acids.Molecular simulation’s results showed the catalytic decarboxylation mechanisms of different type naphthenic acids were different over Bronsted acid site. If the carboxyl group connected to the naphthene directly, there are two reaction pathways. Opening ring firstly and then decarboxylation is the domaint reaction pathway. If the carboxyl group connected to the naphthene through alkyl chain, catalytic decarboxylation mechanism was similar to the carbonium ion reaction mechanism. The bond orders changed after ketonic oxygen contacted to the Bronsted acid site. Bond ofβposition broke to produce methanoic acid, and then the methanoic acid decomposed to CO and H2O. Adsorptive capacities of naphthenic acids and basic nitrogen-containing compounds in porous channels of zeolites were different. Combining capacities of basic nitrogen-containing compounds and zeolites were higher than that of naphthenic acids. As a result of the steric effect, adsorptive capacities of small molecular compounds in porous channels of zeolites were even more.Although the quality of Sudanese Dar high TAN crude oil was inferior, it was very easy to catalytic crack because of the paraffin performance. Conversion was above 90% and liquid yield was above 80% at the condition of reaction temperature of 460℃, residence time of 1.15s and ratio of catalyst to oil of 6. Content of propylene and butylenes in LPG surpassed 80%. Olefins content in gasoline was under 40%. Because carbon residue was more than 8%, coke yield of Sudanese Dar high TAN crude oil was high in catalytic cracking process. Commercial test for catalytic cracking of Sudanese Dar high TAN crude oil verified the research results in laboratory, and more superior product distribution was obtained. Single-through conversion of the crude oil was very high, so recycle oil and slurry oil didn’t need to reprocess. However, high coke yield made the carbon burning load of regenerator to increase greatly. This changed the heat distribution of reaction reproduction system. Heat to warm up the air that needed to burning coke was the main heat consumption. As a result of the existence of distillation diesel in crude oil, quality of the catalytic cracking diesel from Sudanese Dar high TAN crude oil was better than traditional catalytic cracking diesel, and the acidity was also qualified.Economic analyses for various processing schemes of Sudanese Dar high TAN crude oil indicated that direct catalytic cracking had the best economic efficiency. Total cost of the products was more 350 yuan/t than that of tranditional processing scheme, and was more 428 yuan/t than that of delayed coking scheme. Although energy consumption of catalytic cracking process was higher than that of delayed coking process and tranditional processing scheme, gross profit was more than 317 yuan/t and 315 yuan/t. If including the costs of various demulsifier, defoamer, corrosion inhibitor and labour, the profit difference would further increase.更多还原