I. Process Control Requirements Cangzhou Refinery I Catalytic Cracking Unit is the first catalytic cracking unit in Cangzhou Refinery. The system control and monitoring points are required as follows: (1) AI: 330 (2) DI: 96 (3) PI: 16 (4) AO: 80 (5) DO: 32 The operation and management requirements are as follows: (1) The main operating stations (3 units) are required to be placed in a unified centralized operating room, which is 300 meters away from the control station; (2) An external operator's operating station is set up next to the control station; (3) All system variable data must be entered into the plant-level management network. The requirements for the control functions of the DCS system are as follows: (1) All host parts, I/O parts, real-time communication network parts of all control stations are required to be fully redundant; (2) The structure of the system control modules is open to users, and users can develop their own functional modules; (3) It has a platform to support the development of advanced control software; (4) It has the general functions of other DCS systems. II. System Structure The Canglian I Catalytic Refinery Youli 2000DCS system consists of 3 control stations, 4 operator stations, 1 gateway unit, 1 manual operator console, and a real-time dual-redundant communication system. Its architecture is shown in the figure. III. System Operation Status The Canglian I Catalytic Refinery Youli 2000DCS system was successfully put into operation in November 1991 and operated normally for 6 years. During a major overhaul in October 1997, it was updated to the new version of the Youli 2000DCS system, which continues to operate normally to this day. User feedback has been positive. The Youli 2000DCS system has undergone years of testing in important plants at Canglian I Catalytic Refinery, especially in applications within the petrochemical industry, and its comprehensive performance—reliability, practicality, and advanced technology—is among the leading levels in China. IV. System Features (1) The Canglian I Catalytic Youli 2000DCS system is the first domestically produced DCS system applied to catalytic cracking reaction units; (2) The analog I/O boards of the new version of the Youli 2000DCS system all adopt intelligent control processors, and all output I/O boards have their own input verification function; (3) Signal conditioning adopts the form of single-channel signal conditioning modules and can be replaced online, thereby meeting the requirements of mixed use and greatly improving the maintainability of the system; (4) The main control room is placed more than 300 meters away, and two sets of dual-redundant communication cables are connected by dual-redundant optical fibers to realize long-distance real-time communication and real-time operation; (5) The gateway connects the DCS system with the plant management system (WINDOWS NT, SQL SERVER).