The Logic Behind The Magic. “Emergency Shutdown System (ESD) Operating Philosophy 1"

The Emergency Shutdown (ESD) System is designed to protect the personnel, plant, equipment and the environment against pollution. The purpose of the ESD system is to monitor process safety parameters and activate or shutdown the process system and/or the utilities if these parameters deviate from normal conditions.

Usually there are several levels of shutdown:

·         ESD 0 :                       Total emergency shutdown  with abandon of platform

·         ESD 0.1 :                    Black shutdown

·         ESD 1 :                       Total plant emergency shutdown

·         ESD 2 :                       Total process shutdown

·         ESD 3 :                       Local unit shutdown

The ESD system operates in a fail safe mode, i.e. de-energized status of any digital sensor (input) or actuator (output), and fault detection of any critical system component and field inputs/outputs shall result in an action that will bring the plant to the safe condition (energised in normal condition).

Setting sequence of the ESD is as follows :

·         ESD alarm level is sent to the operating console to advice the operator on the process and ESD displays

·         ESD alarm may be acknowledged from Operating Console

Packages start-up sequence is initiated after ESD logic reset as per the following sequence :

·         ESD logic is reset at Operating Console

·         Operator to restart packages locally and manually

Motors start-up sequence is initiated after ESD logic reset as per the following sequence :

·         ESD logic is reset at Operating Console

·         Operator to restart manually motors at Operating console or locally

The control valve can be controlled by the PCS when the ESD logic is reset.