| 摘要 |
A combination valve is disclosed which is useful in flash extrusion of polymer-liquid mixtures or polymer solutions. The combination valve comprises an automatically actuated main process fluid valve (13, 14) and an automatically actuated prime-flush valve (25, 26) in communication with the main process fluid channel (24) just downstream from the main process fluid valve. In operation the prime-flush valve is opened at start up to supply fluid under pressure to the main process fluid channel so that solvent does not evaporate and leave solid polymer to plug the system when the main process control valve is first opened. A shutdown, just as the main process control valve is being closed the prime-flush valve is opened to supply fluid to the system and remove polymer therefrom before it can solidify and plug the system thereby interfering with the next start up. |
