Why have CNOOC Shell, Zhejiang Petrochemical, CNPC-Saudi Aramco, and Daqing Petrochemical chosen the Spherizone process?

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China Shenhua Petrochemical, CNOOC Shell, Daqing Refining & Chemical, Zhejiang Petrochemical... have all chosen the Spherizone process. As an upgraded version of Spheripol, what improvements does it offer? Keywords | Spherizone process, LyondellBasell; Total word count: 5,082 | Recommended reading time: 31 minutes. Spherizone process units are already in operation in China. The two 450,000-ton/year polypropylene (PP) plants in the second phase of Zhejiang Petrochemical will employ the Spherizone process technology ； The Spherizone process technology will be used for the expansion of the second phase of China Coal Yulin Chemical’s 400,000 tons per year polypropylene production facility ； Baolai Petrochemical’s 200,000 tons per year polypropylene production will utilize the Spherizone process technology ； Sinopec Refining’s 200,000 tons per year polypropylene plant will use the Spherizone process technology... This new facility favors the Spherizone process – let’s explore the reasons behind that. https://mpt.135editor.com/mmbiz_gif/dczgnL1qJAtNopqbYfYXxQEnIXg0r06WkMaqvvUxCyo02Ir2Kc28RZJh4ndEC0n5vAL*aYUibVNmEQ461ONKTmA/640?wx_fmt=gif The Spherizone process is the latest generation of polypropylene production technology developed by LyondellBasell on the basis of the Spheripol process. It utilizes fourth- and fifth-generation Z-N catalyst systems with high efficiency, as well as advanced additive systems, and employs gas-phase circulation technology to produce polymers that are more uniform, while maintaining toughness and processability along with high crystallinity and stiffness. The Spherizone gas-phase loop reactor has two interconnected zones, which enable the production of resins with different relative molecular masses and monomer composition distributions, thereby expanding the performance range of polypropylene. Downstream of the loop reactor is connected a gas-phase reactor from Basell Company, which is used to produce multiphase copolymers with higher impact strength or greater toughness compared to other processes. Therefore, the Spherizone process can produce a wide range of high-performance polypropylene products that are either monomodal or bimodal, including homopolymers, random copolymers, and impact-resistant copolymers. https://mpt.135editor.com/mmbiz_png/dczgnL1qJAtNopqbYfYXxQEnIXg0r06W03czxroXSzTk9IHpK837HKtCHePbj4ibBbJtHsMYEHPO8uZcJTtmpGQ/640?wx_fmt=png1 Characteristics of the Spherizone process https://mpt.135editor.com/mmbiz_png/dczgnL1qJAtNopqbYfYXxQEnIXg0r06W03czxroXSzTk9IHpK837HKtCHePbj4ibBbJtHsMYEHPO8uZcJTtmpGQ/640?wx_fmt=png This process utilizes the MZCR technology of multi-zone cyclic reactors, which divides a single reactor into two reaction zones whose conditions can be controlled independently, thereby enabling multi-zone cyclic polymerization within the reactor. In a multi-zone circulating reactor, the catalyst reacts with propylene in a gas phase; the reaction mixture is circulated multiple times between the two reaction zones. The reaction temperature, hydrogen concentration, and monomer concentration can be controlled separately. The gradually growing polymer particles undergo rapid and repeated circulation within these two reaction zones, resulting in a uniform mixing pattern similar to that of an \"onion\" inside the polymer particles. This approach enables the production of homopolymer products with uniform quality and molecular weight distributions that range from narrow to wide, as well as random copolymer products with improved overall properties, and various new types of multiphase polymers. https://mpt.135editor.com/mmbiz_png/dczgnL1qJAtNopqbYfYXxQEnIXg0r06WMn9VicHibW2CawXOSrcoKwG7LT4Cz7CAdRdkBafQ9RcaHTtiaEuoIYWsw/640?wx_fmt=png1 https://mpt.135editor.com/mmbiz_png/dczgnL1qJAtNopqbYfYXxQEnIXg0r06WMn9VicHibW2CawXOSrcoKwG7LT4Cz7CAdRdkBafQ9RcaHTtiaEuoIYWsw/640?wx_fmt=png (1) According to the fragment model, the polymer particles produced by traditional methods such as Spheripol have a two-layer onion-like structure (as shown in Figure 1). Figure 1 Comparison of polymer particles produced by traditional multi-stage processes and the Spherizone process. In this case, if there are significant differences in the molecular weight or crystallinity of the polymers, it becomes difficult to mix them effectively during processing; this can lead to the formation of \"gels,\" which in turn cause \"fish-eye\" defects in film or tube products, severely affecting their mechanical and optical properties. The final polymer particles resulting from the Spherizone process have a multi-layered onion-like structure; during processing, each layer of these particles breaks down into smaller fragments, with an average size equal to the thickness of that layer – which is the smallest dimension at which they exist in the polymer melt in the form of \"islands\". This “island” prevents the formation of any larger-sized uneven micro-regions, thereby eliminating completely the “fish eye” or “gel” effects that can occur as a result of processing. https://mpt.135editor.com/mmbiz_png/dczgnL1qJAtNopqbYfYXxQEnIXg0r06WMn9VicHibW2CawXOSrcoKwG7LT4Cz7CAdRdkBafQ9RcaHTtiaEuoIYWsw/640?wx_fmt=png2https://mpt.135editor.com/mmbiz_png/dczgnL1qJAtNopqbYfYXxQEnIXg0r06WMn9VicHibW2CawXOSrcoKwG7LT4Cz7CAdRdkBafQ9RcaHTtiaEuoIYWsw/640?wx_fmt=png (2) The Spherizone process utilizes a multi-zone circulating reactor, which enables the production of bimodal products within the same reactor. The polymer particles produced have excellent uniformity, especially those of bimodal products; the overall performance of these products is superior to that obtained using processes such as Spheripol. https://mpt.135editor.com/mmbiz_png/dczgnL1qJAtNopqbYfYXxQEnIXg0r06WMn9VicHibW2CawXOSrcoKwG7LT4Cz7CAdRdkBafQ9RcaHTtiaEuoIYWsw/640?wx_fmt=png3https://mpt.135editor.com/mmbiz_png/dczgnL1qJAtNopqbYfYXxQEnIXg0r06WMn9VicHibW2CawXOSrcoKwG7LT4Cz7CAdRdkBafQ9RcaHTtiaEuoIYWsw/640?wx_fmt=png (3) In the Spherizone process, the ratio of H2 addition in the two zones can reach 1:100, whereas in processes such as Spheripol, the ratio of H2 addition in the two ring tubes is 1:10. This allows the Spherizone process to produce products with a wider molecular weight distribution, thereby improving the processing properties of these products. Moreover, since it is a gas-phase reaction technology, there are no limits on the amount of hydrogen and ethylene that can be added, allowing for a wider range of products to be manufactured. Not only can all the products produced using processes such as Spheripol be made, but also entirely new products that cannot be produced via the Spheripol process, such as homopolymer and random copolymer products. https://mpt.135editor.com/mmbiz_png/dczgnL1qJAtNopqbYfYXxQEnIXg0r06WMn9VicHibW2CawXOSrcoKwG7LT4Cz7CAdRdkBafQ9RcaHTtiaEuoIYWsw/640?wx_fmt=png4https://mpt.135editor.com/mmbiz_png/dczgnL1qJAtNopqbYfYXxQEnIXg0r06WMn9VicHibW2CawXOSrcoKwG7LT4Cz7CAdRdkBafQ9RcaHTtiaEuoIYWsw/640?wx_fmt=png (4) The Spherizone process features high reaction yields; the catalyst activity is above 40,000 kg/kgcat, and the consumption of both main catalysts and promoters is low. Most products can be manufactured using a conventional catalyst (ZN118), whereas processes such as Spheripol require succinate-based catalysts to produce high-performance products (such as those with high rigidity and high transparency). Succinate ester catalysts not only have low activity, but their price is also 30% higher than that of conventional catalysts (ZN118). https://mpt.135editor.com/mmbiz_png/dczgnL1qJAtNopqbYfYXxQEnIXg0r06WMn9VicHibW2CawXOSrcoKwG7LT4Cz7CAdRdkBafQ9RcaHTtiaEuoIYWsw/640?wx_fmt=png5https://mpt.135editor.com/mmbiz_png/dczgnL1qJAtNopqbYfYXxQEnIXg0r06WMn9VicHibW2CawXOSrcoKwG7LT4Cz7CAdRdkBafQ9RcaHTtiaEuoIYWsw/640?wx_fmt=png (5) The residence time for the polymerization reaction in the Spherizone process is around 1 hour; the time required to switch products is short, and there is little transition material. https://mpt.135editor.com/mmbiz_png/dczgnL1qJAtNopqbYfYXxQEnIXg0r06WMn9VicHibW2CawXOSrcoKwG7LT4Cz7CAdRdkBafQ9RcaHTtiaEuoIYWsw/640?wx_fmt=png6https://mpt.135editor.com/mmbiz_png/dczgnL1qJAtNopqbYfYXxQEnIXg0r06WMn9VicHibW2CawXOSrcoKwG7LT4Cz7CAdRdkBafQ9RcaHTtiaEuoIYWsw/640?wx_fmt=png (6) Polypropylene products manufactured using the Spherizone process; in these random copolymer products, the ethylene content can be as high as 7%, while the rubber phase accounts for over 40%. In impact copolymers, the ethylene content is above 25%. A high ethylene content enhances the transparency and heat-sealing properties of these products. The Spherizone process can produce both homopolymers and random copolymers, achieving a good balance between the ethylene content and xylene-soluble substances – a balance that other processes are not able to achieve at present. https://mpt.135editor.com/mmbiz_png/dczgnL1qJAtNopqbYfYXxQEnIXg0r06WMn9VicHibW2CawXOSrcoKwG7LT4Cz7CAdRdkBafQ9RcaHTtiaEuoIYWsw/640?wx_fmt=png7https://mpt.135editor.com/mmbiz_png/dczgnL1qJAtNopqbYfYXxQEnIXg0r06WMn9VicHibW2CawXOSrcoKwG7LT4Cz7CAdRdkBafQ9RcaHTtiaEuoIYWsw/640?wx_fmt=png (7) In the event of power outages or other such incidents, the reactor does not need to release large amounts of material, thereby reducing significant losses of propylene. https://mpt.135editor.com/mmbiz_png/dczgnL1qJAtNopqbYfYXxQEnIXg0r06WMn9VicHibW2CawXOSrcoKwG7LT4Cz7CAdRdkBafQ9RcaHTtiaEuoIYWsw/640?wx_fmt=png8https://mpt.135editor.com/mmbiz_png/dczgnL1qJAtNopqbYfYXxQEnIXg0r06WMn9VicHibW2CawXOSrcoKwG7LT4Cz7CAdRdkBafQ9RcaHTtiaEuoIYWsw/640?wx_fmt=png (8) The amount of fine powder produced by the Spherizone process is 1/10 that of processes such as Spheripol, making it suitable for producing impact-resistant copolymer products. The Spherizone process is now increasingly mature; this technology enables significant improvements in product performance, further expands the range of applications for these products, allows for the creation of products with better properties that can replace other materials, and offers greater potential for research and development of new products. This technology offers more significant advantages in terms of increasing product strength and improving polymer properties, as well as in reducing residence time, enhancing the efficiency of the reaction volume, improving production efficiency, and increasing production flexibility. Compared to other production processes, Spherizone offers improved performance and a better proton distribution; it is less susceptible to the constraints imposed by various production conditions. Additionally, only three-fifths of propylene is required in its polymerization process, allowing for the production of high-quality, large quantities of polypropylene products with reduced fuel consumption. At present, the production of polypropylene using the Spherizone process accounts for more than half of the total global production of polypropylene; therefore, this process has become the dominant one. https://mpt.135editor.com/mmbiz_png/dczgnL1qJAtNopqbYfYXxQEnIXg0r06W03czxroXSzTk9IHpK837HKtCHePbj4ibBbJtHsMYEHPO8uZcJTtmpGQ/640?wx_fmt=png2 A brief description of the Spherizone process: https://mpt.135editor.com/mmbiz_png/dczgnL1qJAtNopqbYfYXxQEnIXg0r06W03czxroXSzTk9IHpK837HKtCHePbj4ibBbJtHsMYEHPO8uZcJTtmpGQ/640?wx_fmt=png Both the Spherizone process and the Spheripol double-loop reactor process employ a modular design. To produce impact-resistant copolymers, a gas-phase fluidized bed reactor must be installed downstream of the multi-zone reactive reactor. The various stages of this process include: (1) Catalyst feeding and activation – in this stage, the catalyst is prepared and fed in, and it comes into pre-contact with co-catalysts; pre-polymerization occurs with propylene in the pre-polymerization reactor, after which the mixture enters the rising section of the multi-zone reactive reactor where gas-phase propylene polymerization takes place. (2) The polymerization unit involves polymerization reactions in a multi-zone circulating reactor (MZCР), where propylene, along with small amounts of hydrogen and ethylene, react to produce homopolymers and random copolymers. Second, gas-phase polymerization is carried out in a gas-phase fluidized-bed reactor to produce heterogeneous impact-resistant and specialty copolymers. (3) Post-treatment section: The post-treatment of polymer products mainly includes: the separation and recovery of unreacted gaseous monomers; the vaporization and drying of polymers; and the extrusion granulation and mixing packaging of polymers. https://mpt.135editor.com/mmbiz_png/dczgnL1qJAtNopqbYfYXxQEnIXg0r06W03czxroXSzTk9IHpK837HKtCHePbj4ibBbJtHsMYEHPO8uZcJTtmpGQ/640?wx_fmt=png3 Principles, structure, and control of the multi-zone circulating reactor (MZCР). https://mpt.135editor.com/mmbiz_png/dczgnL1qJAtNopqbYfYXxQEnIXg0r06W03czxroXSzTk9IHpK837HKtCHePbj4ibBbJtHsMYEHPO8uZcJTtmpGQ/640?wx_fmt=png The main structure of the multi-zone circulating reactor (MZCР) consists of two sections: an upward tube and a downward tube. Inside the riser, the polymer particles are rapidly fluidized upward by the reaction gas; they are separated from the reaction gas in the cyclone separator at the top of the reactor, and then move downward in a dense packed bed format within the downcomer. The gas exiting the top of the centrifuge is circulated using a centrifugal compressor through external pipelines; the heat of reaction is removed by a shell-and-tube heat exchanger installed on the circulation line, after which it is recycled back to the reactor. The prepolymer enters the bottom of the riser, while the polymer is discharged through two discharge valves at the bottom of the downcomer. The two leg pipes are insulated; the lift pipe can be considered to have a constant temperature, while the temperature of the drop pipe increases significantly. The two sections of MZCР contain reaction zones with completely different hydrodynamic behaviors: one fluidized section, known as the lifting section, where the polymer flows upward rapidly in a fluidized or dilute phase; and a compact section with downward gravitational flow, known as the dropping section. This creates two different reaction environments within a single reactor: after reacting in the rising section, the polymer particles pass through a barrier section before entering the descending section to continue reacting, and then they are recycled back to the rising section for further reaction, in this repeating cycle. This technology enables gas-phase single-loop tubular reactors to function as if they were an infinite number of reactors, allowing almost every catalyst particle to serve as an effective bed in order to obtain polymers at the molecular level and produce new types of polypropylene products. The presence of the blocking section enables the reactor to operate in two modes: single-peak operation and double-peak operation. In single-peak operation, the same polymer is produced in the two reaction zones of the reactor; that is, the components in the rising zone and the falling zone are identical. However, different consumption rates of hydrogen, ethylene, and propylene result in changes in the molar composition. Single-peak operations do not require a barrier section; the gas used for flushing and purging propylene in the feed and discharge sections comes from the top of the high-pressure bag filter, being powder-free to prevent clogging of the feed nozzles or polymer caking. During twin-peak operation, different products are produced in the two zones of a multi-zone batch reactor. Liquid propylene is used as a barrier liquid in the barrier zone, thereby creating two distinct reaction environments in the rising and falling zones. By adjusting the concentrations of hydrogen, ethylene, and propylene, polymers or copolymers with varying molecular weight distributions can be produced. A multi-zone circulating reactor can be divided into six sections, as shown in Figure 2. Figure 2 Schematic diagram of the multi-zone circulating reactor structure: (1) The “J” section at the bottom of the reactor – fresh propylene enters the reactor here, while liquid propylene is vaporized in the “J” section. When the gas-phase circulation compressor stops and the reactor is drained urgently, the discharge valve at the bottom of section “J” will open to empty the polypropylene powder accumulated at the bottom. However, clumping of the polymer may occur at the discharge valve, blocking the pipeline. (2) The catalyst prepolymer in the reactor’s lifting section enters the reactor from the bottom of this section; under the action of the gas-phase circulation compressor, an upward-flowing fluidized bed is formed, and gaseous propylene undergoes polymerization reaction in the presence of the catalyst. The fluidized bed state in the rising section is controlled by parameters such as pressure difference, temperature, density, and gas velocity. When production is operating normally, the fluidization state in the lifting section is good, with similar temperatures at the bottom, middle, and top (the top temperature may be slightly higher). If there are significant temperature differences or density variations, then the amount of gas flow used for fluidization should be adjusted. (3) The “Ω” section of the reactor’s tapered bend: Here, the diameter of the reactor decreases sharply as it moves from the lifting section to this area; the polymer concentration rises, and the velocity of the gas-solid flow increases. This configuration leads to mixing of the solid phase, with the polymer colliding strongly with the pipe walls, and it also causes the reactor to vibrate. Therefore, the gas velocity in the reactor should not be too high. (4) The high-speed polymer in the reactor’s baffled section enters the top of the downflow section tangentially; under the action of the cyclone separator, the polypropylene powder is separated from the gas phase and then enters the reactor’s baffled section, flowing downward in the form of a dense packed bed. When producing monomodal products, the entire reactor functions as a single unit; in this case, the blocking section only incorporates gas-phase propylene to purge the nozzles in that section and prevent clogging. Nozzles are prone to getting blocked by polypropylene particles, so it is essential to ensure an adequate amount of purge gas during production. During bimodal production, liquid propylene is added at this separation section as a separating agent to separate the hydrogen and ethylene carried by the polymer. At the same time, hydrogen and ethylene at the concentrations required for the reaction in the reduction zone are added to the barrier liquid; as a result, under the action of this barrier liquid, the reactor develops two zones with different gas phase concentrations. (5) In the downward feed section of the reactor, the polymer powder flows downward in the form of a dense packed bed. Due to its high density and the ongoing polymerization reaction, the temperature in this section is higher than that in the upward feed section; moreover, the temperature difference from top to bottom is also significant. Proper purging of propylene in the downflow section and control of the solid-phase flow rate of the polymer are key to regulating the temperature in this section. In a dense-phase polymer system, poor flow or localized excessive reaction can easily lead to the formation of local hot spots, which in turn cause the temperature to rise excessively and result in polymer caking, thereby blocking the reactor’s discharge line. The heat generated by polymerization in the reactor is primarily removed by a cooling water heat exchanger, while fine adjustments can be made using the amount of propylene fed into the purge section. The reactor is equipped with three discharge valves, labeled A, B, and C. Valves B and C are used in alternating fashion, while valve A serves as a backup in emergency situations. During production, clogging of these discharge valves often occurs; the flow of material is typically monitored by checking the level of material and the pressure in the discharge lines. When there is a problem with the flow, the relevant valve must be switched immediately to address the issue, so as to ensure that the backup line remains unobstructed and production can continue smoothly. (6) The discharge butterfly valve at the bottom of the discharge section in the ‘L’ section of the reactor is used to control the rate of material discharge from the reactor and to adjust the residence time of the material. The airflow from the gas-phase cycle compressor feeds the material beneath the butterfly valve and transports it through the “L” section to the lifting section, completing the entire cycle of the reactor. In this way, the polymer particles undergo cyclic reactions within the reactor, and the qualified particles proceed from the discharge line to the post-treatment stage. Pre-polymerized catalyst, along with fresh propylene, hydrogen, and ethylene, are continuously added to the reaction system based on the yield; the separated gas phase is filtered and recovered for reuse, resulting in a dynamic cycle within the reaction system. https://mpt.135editor.com/mmbiz_png/dczgnL1qJAtNopqbYfYXxQEnIXg0r06W03czxroXSzTk9IHpK837HKtCHePbj4ibBbJtHsMYEHPO8uZcJTtmpGQ/640?wx_fmt=png4 Future applications of the Spherizone process https://mpt.135editor.com/mmbiz_png/dczgnL1qJAtNopqbYfYXxQEnIXg0r06W03czxroXSzTk9IHpK837HKtCHePbj4ibBbJtHsMYEHPO8uZcJTtmpGQ/640?wx_fmt=png In summary, the structure and working principle of multi-zone circulating reactors are briefly introduced. The Spherizone process **expands the performance range of polypropylene products; the unique design of the multi-zone continuous reactor, along with the catalysts provided by Basell that offer high yields and selectivity, further enhances the performance limits of polyolefins. The Spherizone process enables the production of high-quality products, including all conventional polypropylene grades as well as some unique special polyolefin product grades. The Spherizone process is an efficient gas-phase production method that allows for a wide range of product variations; it is suitable for producing impact-resistant polypropylene products, features good safety, is easy to start up and shut down, involves single-step treatment of the polymer powder in a degassing chamber, and requires few pieces of equipment. However, multi-zone loop reactors are prone to the formation of local hot spots that cause polymer caking, leading to plant shutdowns and affecting the continuous operation cycle of the plant; therefore, it is essential to pay close attention to maintaining the correct amount of antistatic agent added as well as the flow rate of purge propylene during production. Compiled by Longpu Polyolefins; reproduction without permission requires citation of the source