System Title

Automated control system and emergency shutdown protection for compressors and steam drive turbines M-1, M-5, M-6.

Purpose of the System Development

PCS and ESD for compressors and steam drive turbine are aimed for routine metering and monitoring of process parameters, warning and emergency alarm, displaying of process data, automated control, emergency shutdown, automatic startup and warming up, automatic adjustment of rate of compressors and steam drive turbines.

Description of Automation

Turbo compressor is aimed for gas compression. Steam turbine serves as a compressor drive.

Turbo compressor consists of the following components:

• Steam and condensate system consisting of the following:
• Systems for lubricating and control oil
• Unit for interstage cooling for pyrogas
• Systems for nitrogen supply, steam supply and suction from turbo compressor seals
• Electric valves
• Control valves
• System for inhibitor injection
• Condensate facilities

PCS is aimed for the following:

• Process equipment control
• Failure free startup and shutdown of compressors and steam drive turbines and all switching required for that

ESD is aimed for the following:

• Protection of process equipment from destruction and maximum limitation of flammable substances emission into air
• Prevention of emergency situations when deviating from ultimate permissible values of parameters in all operation modes
• Prevention of emergency progression by means of safe shutdown or transfer of the process into safe state as per preset software

System Functions

• Measuring process parameters
• Monitoring of process parameters deviation
• Monitoring of equipment state
• Monitoring of signal confidence (line loss, short circuit etc).
• Self diagnostics of control equipment
• Local/remote (from the operator's work station) control of actuating devices (electric valves) with selection of operation mode
• Automated control of electrically actuated equipment (diagram for automatic transfer switch for oil and condensate pumps)
• Displaying, registration and archiving of parameters
• Warning and pre emergency alarm signaling about parameters deviation and equipment state
• Automatic adjustment of process parameters
• Automatic protection of compressors and steam drive turbines (prevention of emergencies when deviating from preset ultimate permissible values in operation modes and safe shutdown as per preset program)
• Continuous calculation of the compressor set point regarding surge limit
• Compensation of minor process disturbance by anti-surge adjustment as per PID regulation with minimum required opening of anti-surge valve within adjustment limit
• Compensation of major process disturbances through algorithm of staging anti-surge adjustment with minimum required opening of anti-surge valve within adjustment limit
• Monitoring of rotations approaching surge limits as regards flow rate as well as achieving ultimate compression on the each stage, automatically estimated basing on the temperature and pressure of the gas being compressed, at the each sections of the compressor and basing on it - generating an output signal
• Protection of compressors from surge when compressor set point crossing surge line through actuating of anti-surge protection (ASP)
• Provision of feed forward action as regards the main process parameter to anti-surge loop
• Provision of relevant information on the margin to surge, opening anti-surge valve and throttling valve at the inlet, position of compressor set point as regards gas dynamic features
• Supporting preset frequency for turbine rotation with permissible deviation not more than 0.1%
• Automatic adjustment of turbine rotor rotation frequency
• Adjustment for rotation rise speed in the automated mode depending on the steam pressure at the inlet to turbines and gas pressure in compressor suction lines
• Shutdown of compressors and steam drive turbines as per preset shutdown program complying with the sequence of actions and time intervals
• Automatic warming up for turbine as per warming up algorithm and startup chart
• Implementing logic for startup enabling/disabling when startup diagram assembled/disassembled
• Checking up trip points through signal simulation
• Automatic adjustment of process parameters for ethylene and propylene cooling circle
• Recording operation time of turbine units
• Calculation and display of technical - economic rates for turbine unit operation
• Release of archived process data

Design

PCS and ESD are based on Centum CS 3000 distributed control system by Yokogawa.