For 400TPD or smaller liquid plant, with innovative optimized structure design, cold box can be assembled before delivery and connected at site.Compared with loose delivery, installation time and cost are saved to a large extent, and fractionation column enjoys higher quality and reliability. Thanks to know-how technology and imported compressor and turbine, the specific power consumption is lower than similar plants, and this advantage is outstanding especially for liquid plants with internal compressed gas products. Any liquid plant,with hydrogen-free rectified argon system and 100PTD, can produce up to 100 Nm³/h high purity oxygen. With unchanged flow rate and pressure of air compressor, transforming between LOX and LIN partially within certain ranges is available without influence to the purity and quantity of argon.