Recovery of CS2 through condensation

Condensation systems are used for the waste gas from the spinning lines, where the CS2 from the spinning frames is condensed for further use in the production process. 

A mixture of steam, CS2 and air with a temperature of approximatly 95 °C is sucked off from the CS2-box. Most of the vapour is condensed in the vapour condenser by mixing with water. The water temperature at the outlet of the condenser is approximately 70 to 75 °C, and the same water flows back into the acid water circulation system, to compensate for the water carried out of the system by the product. The feed temperature of the water to the vapour condenser should not be lower than 50 °C to avoid condensation of CS2 inside the vapour condenser. 

CS2 and steam-saturated air pass through the condenser where the gases are extracted by a water jet, in which more CS2 is condensed by the cold water. 

The gaseous phase is then separated from the liquid phase by means of an air separator. 

The recovered CS2 is of high purity, so can be used in the viscose process again without an extra cleaning procedure. The water overflow of the settler is nearly CS2 free, and can be eireulated after treatment with caustic soda to remove the remaining H2S. 

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