4.2　Design Elements

4.2.1　DCS should consist of operator workstations，engineering workstations，auxiliary consoles，printers，large size screen，PCs，control stations，I/O cabinets，security isolation safety barrier cabinets and/or terminal cabinets，power distribution cabinets and network device cabinets.FCS should consist of main control system，communication interfaces，fieldbus devices，fieldbus auxiliary devices and fieldbus cables.Common engineering workstations provided in CCR should be used for configuration maintenance，fault diagnosis and startup.APC and RTO devices should be installed in CCR.Common hardware platforms，data acquisition workstation and network interfaces provided in CCR should be used to connect with information systems.Redundant serial communication interfaces shall be provided for each control station to connect with SIS，FGS，CCS，MMS，MAS，PLC and PAS，etc.

4.2.2　SIS shall be designed based on safety integrity level（SIL）required for process units，utilities and auxiliary facilities.SIS loops should be provided for the critical safety interlock protection system，emergency shutdown system and critical equipment interlock protection system.SIS shall communicate real-time data with DCS and shall be provided with engineering workstation and SOE（sequence of events）workstation.Relevant alarms and operations should be performed by the switches and push-buttons on auxiliary consoles and DCS operator workstations.

4.2.3　Design of CCS and MMS shall comply with the following requirements:

1　Individual CCS shall be provided for process plant or unit.

2　CCS shall be provided with functions such as speed control，anti-surge control，load control，process control and interlock protection of compressor trains，and shall communicate with DCS of relevant units.

3　MMS with simple control requirements used for reciprocating compressor and blower may be taken over by DCS or PLC designed for process plants，and safety interlock protection system for the machine trainsunits may be taken over by SIS designed for process plants.

4　MMS for rotating machine trains such as large size motor，steam turbine，compressor and pump shall be designed to monitor mechanical variables and operating status，shall be provided with on-line analysis and diagnosis functions.

5　MMS management workstation shall be provided in CCR.

6　MMS control station shall be located in FAR，and MMS operator workstation shall be located in CCR.

4.2.4　FGS shall be provided based on FAR or process unit，and shall comply with the following requirements:

1　Each system shall be provided with two loops of communication networks in redundant configuration.One loop should be connected to plant-wide FGS and automatic fire extinguishing system，and to fire fighting station as well.The other loop should be connected to DCS for the related process units.DCS operator workstation dedicated for FGS display and alarm shall be provided in CCR.

2　Flammable or toxic gas detectors shall be provided at the locations where flammable or toxic gas may leak or accumulate in process unit，and signals from such detectors shall be connect to FGS or DCS for process unit.

4.2.5　APC and RTO should be designed and executed based on process requirements of process units.

4.2.6　MAS shall be consistent with the automatic control level for process unit，and shall be designed with centralized control，monitoring，management，recording and alarm functions.

4.2.7　For PAS that comprises complex on-line analyzers such as process gas chromatograph，process mass spectrograph，infrared analyzer，trace moisture analyzer and oxygen analyzer，it shall include sampling unit，preliminary sample treatment unit，sample pre-conditioning unit，analyzer unit，recovery or vent unit，microprocessor unit，communication interface unit，human-machine interface and printer，and shall be provided with the interface to communicate data with DCS.

4.2.8　SCADA shall provide monitoring and control for both the equipments remotely located and the consumptions of utilities such as water，power，steam and air systems.It shall be designed with data acquisition，parameter recording and alarm，and equipment monitoring functions.

4.2.9　CCTV used to monitor and supervise critical locations and equipments shall be provided based on plant safety requirements.