[Haichuan Chemical Salary Updates] CNOOC Ningbo Daxie 3.4 million tons/year disproportionation project kicks off

Fractionated oil refers to the components separated during the distillation of crude oil, which have a specific boiling range; examples include liquefied gas, gasoline, kerosene, diesel, and other such fractions. Chinese name: Fufen oil; the one obtained through vacuum distillation is called vacuum distillate. What remains at the bottom of the distillation tower is known as residue. Distillates are only similar in terms of boiling point range; they are not yet petroleum products, and further processing is required to turn them into petroleum products that meet the specified requirements.

CNOOC Daxie Petrochemical’s Distillate Oil Project Goes into Operation 2016-07-06 02:53 China Science and Technology Network, Science and Technology Daily Report (Reporter Qu Jian) According to the latest updates from China National Offshore Oil Corporation, the Daxie Petrochemical Distillate Oil Comprehensive Utilization Project, with a total investment of 13 billion yuan, was officially put into operation in Ningbo, Zhejiang. The project will install 15 sets of production facilities that are among the best in China; among these, the catalytic cracking (DCC) unit with an annual capacity of 2.2 million tons is the largest of its kind in China and ranks second in the world. Once the project is put into operation, it will be able to produce nearly 20 types of chemical products, as well as diesel and aviation kerosene, on an annual basis. The annual production volume is expected to reach 7 million tons, which will provide strong support for Ningbo in developing as one of the **seven newly planned petrochemical industry hubs, with a focus on diversification, sophistication, and integration. Dong Xiaoli, general manager of CNOOC Refining & Chemicals Company, said that Daxie Petrochemical is the second refinery and chemical complex with a production capacity of 10 million tons in China, built by CNOOC following the one in Huizhou, Guangdong, in line with the principles of large-scale operation, differentiation, intensification, integration, and sustainability. Its distillate oil comprehensive utilization project is equipped with 15 production units that are among the best in China, as well as auxiliary facilities for oil storage and transportation and utility services; all of these units feature online intelligent control. Among them, the catalytic cracking capacity of 2.2 million tons per year, the gas fractionation capacity of 1 million tons per year, and the styrene production capacity of 280,000 tons per year are all the largest single-unit facilities of their kind in China ； The scale of the continuous reforming, diesel hydrogenation, and wax oil hydrogenation units also ranks among the largest of their kind in China. The project uses the wax oil produced by the existing atmospheric and vacuum distillation units as raw material, and employs processes such as catalytic cracking and catalytic dry gas conversion to ethylbenzene. These methods help to maintain advanced technical and product standards while reducing energy and material consumption. Furthermore, the localization rate of this project reaches 96%, the highest among similar devices. The project leader noted that the manufacturing and installation of the two core DCC equipment units – the reaction settler and the regenerator – are a major highlight of the project. To address challenges such as a narrow construction site, a limited lifting radius, a high vertical lifting height, and great difficulties in lifting, Daxie Petrochemical adopted a scientific approach that involved manufacturing the components in the factory, carrying out stress-relief heat treatment, and then transporting them by sea to the site where the shell sections were lifted, welded together, and the internal components were installed. As a result, the project was completed more than two months ahead of schedule. At present, all units of the project are operating well, and the first batch of high-value-added products has been successfully launched on the market. The official revealed that, in addition to this project, the distillate oil expansion and renovation project was also launched in February 2016 and is set to be completed by the end of 2018. The two projects will create a circular economy chain that covers both upstream and downstream processes, with no residual waste.

Disproportionation reaction, also known as auto-redox reaction, is a type of chemical reaction in which the oxidation state of a certain element increases as well as decreases. A reaction process in which the same molecules give rise to two different molecules under certain conditions due to the transfer of atoms (groups) between them.

Process conditions: The disproportionation reactions of olefins and alkyl aromatics are both reversible reactions with very low enthalpy of reaction; therefore, temperature has little effect on the equilibrium composition. The equilibrium conversion rate is generally 35% to 50% (on a molar basis), and in industry, these disproportionation reactions are usually carried out until near the equilibrium conversion rate is achieved. The reaction temperature is 300–530°C, and the pressure is 1–5 MPa. Due to the tendency of catalysts to coking easily during the alkylation aromatics disproportionation process, the reaction is often carried out under pressure in the presence of hydrogen, a process known as hydrodisproportionation. There are also normal-pressure disproportionation processes carried out in the absence of hydrogen, requiring frequent catalyst regeneration. Since aromatic hydrocarbon disproportionation catalysts can also catalyze alkylation reactions, when toluene is disproportionated, the addition of a certain amount of nonane aromatic hydrocarbons (mainly trimethylbenzene) to the starting toluene allows the molar ratio of xylene to benzene in the products to vary within the range of 0.7 to 10, thereby enhancing the flexibility of production. The characteristic of the disproportionation reaction is that there are very few by-products, and the products are easy to separate, resulting in a high purity of the product. Adiabatic fixed-bed reactors are commonly used for disproportionation reactions; when the catalyst particles are small, radial fixed-bed reactors can also be employed to reduce bed resistance and secondary reactions. For atmospheric-pressure disproportionation processes in the absence of hydrogen, where the catalyst needs to be regenerated frequently, a moving-bed reactor can be used.

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