Why are screw compressors rather than centrifugal compressors used in the refrigeration systems for chlorine liquefaction

I. Basic Principles and Characteristics of Screw Air Compressors 1. Basic Principles: The cylinder of a screw compressor has a “∞” shape, and inside it there are two interlocking male and female screw rotors that rotate in opposite directions at a specific ratio. 　　When a screw compressor is in operation, gas enters the cavities between the teeth of the male and female screws through the suction inlet. As the screws continue to rotate, the volume of these cavities increases continuously; when this volume reaches its maximum value, the connection to the suction inlet is severed, and the suction process comes to an end. The compression process follows immediately thereafter; the intermeshing of the male and female screws causes the volume between the teeth to decrease continuously, resulting in an increasing pressure of the gas. When the volume between the teeth becomes connected to the exhaust port, the compression process ends and the exhaust process begins ； During the exhaust process, the continuous rotation of the screw continuously sends compressed air to the exhaust pipeline. 　 　2. Main features: In terms of the compression principle, screw compressors are the same as piston compressors; they belong to the volumetric type ； In terms of the type of motion, the screw type, like the turbine type, performs high-speed rotational motion ； Therefore, the screw compressor possesses the characteristics of both. 　　 A. High speed, compact structure ； The volume, weight, and floor space per unit of displacement are all much smaller than those of piston engines. 　 B. It has no vulnerable components such as gas valves or piston rings, thus offering reliable operation, a long service life, and easy remote monitoring. 　　 C. Even intake and exhaust flow without pressure pulses, and since there are no unbalanced inertial forces, no foundation is required for installation. 　　 D. Screw compressors with injection can achieve a high single-stage pressure ratio and a low exhaust temperature. 　　 E. It features forced exhaust, meaning that the exhaust volume is not affected by the exhaust pressure. 　　 F. When the operating point varies over a wide range, the machine’s efficiency remains relatively constant, and there is no surge phenomenon that occurs in speed-type compressors at low discharge volumes. 　　　　 II. Basic Principles and Characteristics of Centrifugal Air Compressors 1. Basic Principles A centrifugal air compressor uses a high-speed rotating impeller to subject air to centrifugal force, thereby generating pressure and increasing its speed. After leaving the impeller, the air passes through expansion channels such as diffusers, where its kinetic energy is gradually converted into pressure energy, resulting in an increase in pressure. Once one stage of compression is completed, the air moves on to the next stage, until the desired pressure is reached at which point it is discharged. 　　Centrifugal air compressors are generally composed of multiple stages; the higher the discharge pressure, the more stages are required. They are divided into several sections, with intermediate gas coolers between each section. 　　 2. Main features: A. High rotational speed, compact structure, wide displacement range ； 　　 B. High requirements for manufacturing, operation, and maintenance; difficult to implement ； 　　 C. Changes in displacement have a significant impact on mechanical efficiency ； 　　 D. Surge is likely to occur during startup and shutdown processes ； 　　 E. High noise in the gearbox is difficult to control ； 　　 F. Compressed air is cooled without lubricant, ensuring high air quality ； The above was found on the Internet; I don’t know the specific reason either

For reasons related to equipment maintenance, operation, and stability, more manufacturers currently use screws