The Spheripol process was successfully developed by Basel Polyolefins. Since its first industrialization in 1982, it has been the most successful and widely used polypropylene production process to date. The Spheripol process is a polymerization process that combines liquid phase prepolymerization with liquid phase homopolymerization and gas phase copolymerization. The process uses a high-efficiency catalyst to produce PP powder with a spherical particle size. The powder produced by its catalyst is large and uniform, and the distribution can be adjusted, either wide or narrow. A full range of multi-purpose products can be produced. Its homopolymer and random copolymer products are characterized by high clarity, good optical properties, and no odor.

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The liquid phase loop reactor used in the Spheripol process has the following advantages:

(a) It has a high reactor time-space yield (up to 400kgPP/h.m3), the reactor volume is small, and the investment is small;

(b) The reactor structure is simple, the material requirements are low, and low-temperature carbon steel can be used. The design and manufacture are simple. Due to the small pipe diameter (DN500 or DN600), the pipe wall is thin even at high pressure;

(c) The straight leg part of the jacketed reactor can be used as a support for the reactor frame. This structural design reduces investment;

(d) Due to the small reactor volume, the residence time is short, the product switching is fast, and the transition material is small;

(e) The polymer particles are suspended in the propylene liquid, and there is good heat transfer between the polymer and propylene. The cooling jacket is used to withdraw the heat of reaction. The heat transfer area per unit volume is large, the heat transfer coefficient is large, and the overall heat transfer coefficient of the loop reactor is as high as 1600W/(m2.бц);

(f) The slurry in the loop reactor is circulated at high speed by an axial flow pump, and the fluid flow rate is as high as 7m/s, so the polymer slurry can be stirred evenly, the catalyst system is evenly distributed, the polymerization reaction conditions are easy to control and can be controlled very accurately, the product quality is uniform, it is not easy to generate hot spots, it is not easy to stick to the wall, and the energy consumption of the axial flow pump is also low;

(g) The polymer slurry concentration in the reactor is high (mass fraction greater than 50%), the reactor has a high single-pass conversion rate, and the single-pass conversion rate of homopolymerized propylene is 50%-60%. The above characteristics make the loop reactor very suitable for the production of homopolymers and random copolymers. The Spheripol process initially used high-efficiency catalysts such as GF-2A, FT-4S, and UCD-104, with a catalyst activity of 40kgPP/gcat and a product isotacticity of 90%-99%, without deashing or removing random substances.

Currently, the technology has developed to the second generation. Compared with the first generation technology using a single loop reactor, the second generation technology uses a double loop reactor, and the operating pressure and temperature are significantly improved, which can produce bimodal polypropylene. The catalyst system uses the fourth or fifth generation ZN high-efficiency catalyst, adds a hydrogen separation and recovery unit, improves the high-pressure and low-pressure degassing equipment of the polymer, and improves the steaming, drying and propylene accident discharge units. The flexibility of operation is increased, the efficiency is improved, and the consumption of raw monomers and various public works is also significantly reduced. The particle size of the obtained product is more uniform, and the melt flow index range of the product is wider (from 0.3-1600.0g/10min), which can produce new PP grades with high rigidity, high crystallinity and low heat sealing temperature. The impact copolymerization reaction of the Spheripol process is produced by gas phase method, and the reactor is one or two dense phase fluidized bed reactors in series {HotTag}. The reactor adopts gas phase dense phase fluidized bed. A gas phase reactor system can produce impact copolymers with an ethylene content of 8%-12% (mass fraction). If it is necessary to produce special impact copolymers with a higher rubber phase content and possibly more than one dispersed phase (such as low stress whitening products), it is necessary to design two gas phase reactor systems to keep the gas phase composition and operating conditions in the two gas phase reactor systems independent, so that two different copolymers can be obtained and added to the homopolymer.

The two-step method of steaming and drying can be used to treat the polymer, and the steam in the steaming tail gas can be easily condensed to separate pure hydrocarbon monomers, which can completely recycle the hydrocarbons in the tail gas and reduce the consumption of monomers. The closed-loop nitrogen drying system also reduces the nitrogen consumption of the device. In addition, the Spheripol process adopts a modular design method, which can meet the requirements of different users, is easy to build in steps (such as first installing a homopolymer production system and then adding a gas phase reaction system at the right time), and the production capacity of the device is also easy to expand. The Spheripol process has a strict and complete safety system design, which makes the device have high operational stability and safety. The new generation of Spheripol process uses a pure additive addition system to make the product quality more uniform and stable, and it is convenient for product switching. The Spheripol process technology can provide a full range of products, including homopolymers, random copolymers, impact copolymers, and terpolymers (ethylene-propylene-butene copolymers). The MFR range of its homopolymer products is 0.1-2000g/10min, the MFR of industrial products reaches 1860g/10min (special non-granulated products), and the bending modulus of high-rigidity products reaches 2300MPa. The ethylene content of industrially produced random copolymer products is as high as 4.5% (mass fraction), and there are ethylene-propylene-butene terpolymer products. The film sealing starting temperature is as low as 110буC, which can compete with high-ethylene content random copolymers produced by gas phase process. Impact copolymer products have good comprehensive properties of rigidity and impact resistance, and the product ethylene content can be as high as 25% (40% rubber phase). In addition, the Spheripol process can flexibly adjust the molecular weight distribution of the product between the polymer dispersion index (PI) of 3.2-12 according to product needs by adding peroxide and double loop reactors. It can directly produce products with MFR up to 1800g/10min in the reactor and large particles without granulation, making the Spheripol process highly competitive. Another feature of the Spheripol process is advanced catalyst technology. Basell has a variety of catalyst systems that can be used to produce different types of products in the Spheripol process, such as MC-GF2A catalyst for the production of homopolymers, MC-M1 for the production of large spherical impact copolymers and homopolymers and random copolymers, while some high modulus homopolymers require the use of D-donors (dicyclopentyl-dimethoxy-silane, referred to as DCPMC), and some special impact copolymers with high ethylene content also require the use of special catalysts. Basell has registered multiple patents for diether catalysts, which have also been commercialized, such as MC-126 and MC-127. Diether catalysts have high polymerization activity (up to 100Tpp/kg cat) and long life, good isotactic index control, high hydrogen sensitivity, and the product has a narrow molecular weight distribution. At present, there are nearly 100 polypropylene plants in the world using the Spheripol process, with a total production capacity of about 14.6 million tons/year, accounting for about 36.8% of the world's total polypropylene production capacity. Among them, the production capacity in North America is 4.03 million tons/year, the total production capacity in Asia is 4.19 million tons/year, the production capacity in Western Europe is 4.105 million tons/year, the production capacity in Central and Eastern Europe is 620,000 tons/year, and the production capacity in the Middle East and Africa is 1.315 million tons/year.

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