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Polycarbonate (PC) Vacuum Application

January 6, 2019

Polycarbonate (PC) is a linear polymer containing carbonic acid groups in the molecular chain, which can be divided into aliphatic, aromatic, aliphatic-aromatic and other types, but the current industrial production of aromatic polycarbonate. As a high-end petrochemical product, polycarbonate is the fastest-growing thermoplastic material among the five major engineering plastics, with excellent overall performance, and is widely used in electronic appliances, sheet containers, automotive industry, medical equipment, protective equipment and other fields, and is rapidly expanding to aerospace, optical components, optoelectronic information and other emerging fields.

In the polycarbonate production process, phenol recovery towers, DMC recovery towers, DPC recovery towers, thin film evaporators and DPC purification towers all need to use vacuum devices. Shanghai Covestro, Ningbo Daphoon, Lihuayi Group and other companies have adopted the vacuum system of VACCULEX. Here we focus on the vacuum system project of Lihuayi Group Weiyuan Chemical Industry:

Application	Vacuum systems for polycarbonate production
Application overview:
The project contains several vacuum systems with normal inlet pressure ranging from 0.4-100Kpa, outlet pressure of 1 bar(a) and inlet temperature ranging from 45-91.8℃. Media: Air, H₂O, Methanol, Phenol, Phenylmethylcarbonate, Diphenylcarbonate, Anisole, Isopropanol, Methl Methacrylate (formaldehyde methyl acrylate), SO3 sulfur trioxide, ammonia + α-hydroxyisobutyramide Explosion-proof grade:ExDⅡBT4. Some of their components are flammable and explosive, as well as special odor, toxic, highly corrosive and easy to solidify, so the requirements for the unit are higher: 1. explosion-proof; 2. anti-corrosion; 3. zero leakage; 4. temperature rise control. According to the working conditions provided by the customer, we recommended the customer to use Roots liquid ring unit; a total of 39 Roots pumps were used on site, with models MBD240,KMBD400,KMBD720,KMBD1200,KMBD1600,KMBD7300, the main features of MD Roots booster pumps are: direct connection or pulley transmission can be adopted to meet different pumping speed requirements of customers; five-point mechanical seal is adopted to ensure clean and oil-free pump cavity and zero leakage of toxic and harmful gases; internal configuration of Karz O-ring of mechanical seal can ensure safe sealing and corrosion resistance, etc. For system energy saving and pressure stabilization, frequency control is adopted.
Case Summary
Stable control of the system’s gas tightness, temperature, pumping volume and pressure for long-term stable operation of the vacuum system.