Making a 'Smarter' Dryer System: An Experience with 'Smart' Valves and Open Systems

摘要

In May 1995, the steam and condensate system for a linerboard machine was upgraded. The controls were removed from a panel and implemented in a new distributed control system. This control system is linked to a scanning/control system on a standard, "open" LAN using IEEE 802.3 TCP/IP communications. All of the valves (thirty-nine) were refurbished and equipped with "smart" digital positioners. In addition to normal analog control signals (i.e., 4 - 20 ma), the HART protocol is being used to pass actual valve positions to the DCS for display to the operator.