Sinopec SEI “countercurrent” continuous reforming process technology

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This post was last edited by yinkuilin6868 on 2015-11-23 11:08. Sinopec SEI’s “countercurrent” continuous reforming process technology I. Introduction The “countercurrent” continuous reforming process, innovatively developed by Sinopec Engineering Construction Co., Ltd. (SEI), was successfully put into industrial use in 2013. Since its commissioning, the first 600,000 tons per year industrial plant has been operating steadily and continuously, with all performance indicators exceeding those of the traditional \"co-current\" continuous reforming process. Industrial success was achieved through original innovations in process technology and engineering, resulting in fully independent intellectual property rights. “The “counterflow” continuous reforming process introduces and implements a new concept of matching catalyst activity to the difficulty of the reactions. The catalyst and the reaction stream flow in opposite directions; that is, the regenerated catalyst passes sequentially through the fourth reactor, third reactor, second reactor, and first reactor before returning to the regenerator for regeneration. This arrangement allows the catalysts with the highest activity to carry out difficult reactions such as alkane cyclodehydrogenation in the fourth and third reactors, while catalysts with lower activity perform easier reactions such as naphthenene dehydrogenation in the second and first reactors. “The “counter-current” continuous reforming process fundamentally solves the problems associated with the traditional “forward-current” continuous reforming process, namely the mismatch between the difficulty of the reactions and the distribution of catalyst activity, as well as the unreasonable arrangement of catalyst circulation. ““Counterflow” continuous reforming significantly improves the reaction conditions and introduces a new, easy-to-operate catalyst circulation method. Compared with traditional technologies, it has three key technical advantages: 1) The catalyst is transported by the counterflow reaction stream ； 2) The complex locking hoppers and their control systems, which were required in traditional processes, have been eliminated ； 3) Eliminate the regeneration catalyst dust sieving and collection system. II. Process Overview The “counter-current” continuous reforming technology typically consists of four stages: feedstock pretreatment, reforming reaction and product separation, catalyst regeneration, and reformate distillation. 1. Introduction to the process: 1) Reforming reaction section: The reformed feedstock, which has been pre-treated and refined, is mixed with reforming cycle hydrogen. After heat exchange with the reforming reaction products and heating in the first reforming heater, it enters the first reforming reactor, where it reacts with a catalyst. The reactants leaving the first reforming reactor are then sent to the second reforming heater for further heating before entering the second reforming reactor… up to the last reactor. After exiting the last reactor, the reaction products go to the feed heat exchanger to exchange heat with the feed. The heat-exchanged reaction products, after cooling, enter the reformate separation tank where gas-liquid separation takes place. 2) Catalyst regeneration section a) Catalyst circulation: The regenerated catalyst is lifted from the regenerator to the buffer hopper at the top of the fourth reactor using hydrogen; it then flows by gravity through the reduction tank before entering the fourth reactor, and from there it is lifted from the bottom of the fourth reactor to the top of the third reactor... and so on, until it reaches the first reactor. The catalyst to be regenerated is then lifted from the bottom of the first reactor using nitrogen to the separation hopper at the top of the regenerator, where it falls into the regenerator by gravity. Inside the regenerator, the catalyst flows from top to bottom, enters the regenerated catalyst elevator via a nitrogen-sealed tank, thus forming a reaction-regeneration cycle. This process does not feature a closed hopper between the reaction and regeneration systems, nor are there any valves that need to be opened or closed on the catalyst circulation pipeline during normal operation; thus, catalyst circulation and regeneration occur as a true \"valve-free continuous\" operation. b) Catalyst regeneration: The catalyst coking regeneration cycle gas uses a cold circulation process. The recycled gas coming from the charring zone is dechlorinated, dried, and pressurized before being sent to the charring zone and the oxychlorination zone respectively. A cooling zone is located at the lower part of the regenerator; the cooling air passes through this cooling zone and the drying and roasting zone, where it mixes with the gases from the oxychlorination zone before continuing upward. The gas discharged from the exit of the oxychlorination zone is dechlorinated and cooled by water cooling before being led to a safe location for release. 2. Technical features: Reaction section: 1) The regenerated fresh catalyst first enters the rear reactor, where it is used for reactions that are difficult to carry out, thereby enabling the catalyst’s activity to be fully utilized and the reaction conditions to be optimized. 2) The reactors are arranged in a single parallel configuration, featuring a simple structure, easy manufacturing, and convenient operation and maintenance. 3) The reaction pressure adopts the state-of-the-art level for current continuous reforming, with a pressure of 0.24 MPag in the gas-liquid separator. Catalyst circulation section: 1) The transfer of the catalyst from low pressure to high pressure is carried out using a dispersed material seal lifting method, without a closed hopper system, which simplifies the catalyst transfer process. True “valve-free continuous” operation is achieved, resulting in a more stable catalyst flow. 2) Due to the significant reduction in catalyst wear, the dust separation and collection system for regenerated catalysts has been eliminated, resulting in a substantial simplification of the process. 3) The raw catalyst is lifted using nitrogen, while the regenerated catalyst is lifted using hydrogen. Catalyst regeneration section 1) The pressure in the regenerator is between stage 1 and stage 4, which facilitates both the regeneration of the catalyst and its transportation. 2) Two-stage moving-bed coking is employed, with the bed temperature being increased gradually; this makes the coking process more rational and helps to avoid overheating. 3) The regenerator gas circulation adopts a cold cycle process, with a cooling section located at the lower part of the regenerator. III. Calibration of the industrial plant The industrial plant was calibrated under design conditions, and the calibration values for key performance indicators such as pure hydrogen yield, C5+ gasoline yield, and aromatic content in gasoline were all higher than the design values calculated based on a co-current operation mode; moreover, the amount of catalyst dust was significantly lower than the design value. 　　 Name, Specified Value, Design Value (co-current), Increase Percentage, %, Pure Hydrogen Yield, %: 3.99, 3.54, 12.7; C5+ Gasoline Yield, %: 89.70, 89.14, 0.6; Catalyst Dust Amount, kg/day: 0.6, 2.85, -78.9. IV. Economic Aspects: With 100% domestic production of the equipment, the investment required is reduced by more than 5% compared to existing co-current continuous reforming plants.