Smart valve positioner boosts gas production
A modern digital electro-pneumatic valve positioner from ABB minimizes flowrate swings of rich-liquid vapor at an air separation plant in Louisiana. The new positioner replaces one installed on the actuator of a 20-in. butterfly valve. Tighter control of the flowrate has helped to stabilize the sensitive cryogenic distillation process, increasing argon production by 10%. The plant employs cryogenic fractional distillation to separate air into its major components: nitrogen (78%), oxygen (21%), argon (0.96%).
The plant controls the amount of rich-liquid vapor coming off the argon column, which in turn controls the amount of crude argon flow coming into this column. A 20-in. Jamesbury butterfly valve regulates the flowrate of the rich-liquid vapor, which after installation of TZIDC digital electro-pneumatic positioner from ABB, is now flat and smooth.
The plant manager notes that flatter flowrates establish better system equilibrium, maximizing product purity. The plant can now run the air separation columns under tighter control, which results in production of more argon, estimated at about 10% more.
Visit the Control Engineering Process Control Channel.
Edited by Peter Welander, email@example.com