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What is the difference between process shutdown (PSD) and emergency shutdown ( ESD).
 
Answers
27/11/2016 A: Virendra Kapoor, Petroleum Refining Consultants, vkkapoor9@yahoo.com
PSD depends on number of various factors some of which may be:
1-Charge stock, products slate requirements variations, limitations of equipments, exchangers, vessels, columns to meet process demands.
2- Regeneration/ activation of catalyst, management of delta P or heat transfer issues through furnaces/ exchangers, maloperation of compressors, pumps, columns etc.
3- Management of parameters issues that degrade products
ESD is to protect plant, components of plants, catalysts, environment and human beings due to operational upsets that may cause plant, catalyst, manpower safety issues.equipments damage, runaway conditions, overpressurization, process control issues that can not be managed normally. Depending on integrated safety levels emergency plant shut down is for totally safe & secure operation
08/11/2016 A: Yongming Zhang, HQCEC, 13439348666@139.com
I agree with the UOP engineer's answer; the ESD is a higher grade protection system than PSD.
04/11/2016 A: Mohan Shyam Pathak, UOP A Honeywell Company, mohanspathak@gmail.com
As the name suggest, the process shutdown originates from the unwanted process conditions and emergency shutdown originates from emergency related issues.
Process shutdown will be initiated if the control system capture any process abnormalities as defined in the control system design. This system will try to stop propagating the impacts of process abnormalities downstream.
Emergency shutdown will be mostly initiated originating from abnormalities leading to serious safety concerns such as Runaway reactions leading to excessive temperature.
25/10/2016 A: Sridhar Balakrishnan, Bharat Oman Refineries Limited , laksrid@yahoo.com
In case of Emergency system shutdown following things are done : Shutdown of equipment, Isolate hydrocarbon inventories and electrical equipment, prevent escalation of events ,hydrocarbon flow stoppage ,Emergency ventilation control.
In case of Process system shutdown following things are done : Shutdown the whole process or parts of the process system. Depressurize / Blowdown parts of the process.
24/10/2016 A: Jayaraj Jayam, Chennai Petroleum Corporation Limited, njayaraj@gmail.com
Process shut down could be attributed to any planned shut down of the unit. It is an anticipated one and planned to attend the process issues during the favorable situation such as unit feed limited due to downstream unit issues, feed quality affects the unit throughput etc. Otherwise shut down time to be planned according to the severity of the issue.
Whereas emergency shutdown, as the terminology explains it is a forced situation on the process unit. One has to act according to the situation. Using the available resources, plan to go for safe shutdown of the unit as per the SOP of the unit.
Application of mind relating to the situation is the most important aspect as emergencies are always different and may be the type of emergency occurs also new. A very good knowledge about the process, plant and facilities available in the unit are the must to handle ESD safely.