1007 disq 0 p ph 48071 shutdown philosophy

8/9/2019 1007 DISQ 0 P PH 48071 Shutdown Philosophy

1/12

Contract

Number:P1007

File Reference

1007-DISQ-0-P-PH-48071

Page

1 of 12

RWE Dea

Disouq Field Development

FEED

Shutdown Philosophy

Document number1007-DISQ-0-P-PH-48071-Rev.0

0 12.12.11 Issued for Client comment S.Morsi A.Fawzi A.Hamdan RWE

Rev Date Description Issued By Checked By Approved

By

Client

Approval


2/12

Onspec Engineering Solutions

Disouq Field Development Project

Shutdown Philosophy

Page: 2 of 12

Changes List

Rev.Date

prepared (dd.MM.yyyy)

Prepared by Description


3/12



Shutdown Philosophy

Page: 3 of 12

Table of Contents

1 Introduction ...................................................................................................................... 4

1.1

Objectives & Scope ...................................................................................................... 5

1.2

Abbreviations ............................................................................................................... 6

2 Safety Shutdown Philosophy and Principles .................................................................... 7

2.1. Application ................................................................................................................... 7

2.2.

Principles ..................................................................................................................... 7

2.3. Applicable Code ........................................................................................................... 7

2.4. Safety Integrity Level .................................................................................................... 7

3

Logic Hierarchy ................................................................................................................ 8

3.1.

Shutdown Levels .......................................................................................................... 9

4 Process & Utilities Shutdown Events ............................................................................. 11

5

Shut Down Valves design Criteria .................................................................................. 12

5.1 ESD valves ................................................................................................................ 12

5.2

Position Status & Resetting ........................................................................................ 12


4/12



Shutdown Philosophy

Page: 4 of 12

1 Introduction

RWE Dea Egypt has discovered seven natural gas reserves in the Disouq Concession withinthe onshore Nile Delta, starting in 2008, as shown on the concession map below. Furtherexploration in the concession is ongoing. RWE Dea Egypt is the operator of the Concessionwith EGAS as a partner.

The objective of this project is to carry out front end engineering design (FEED) services andprepare a scope of work for Engineering, Installation and Construction tenders (procurement willbe undertaken by RWE Dea) to finally install a natural gas trunk line system to be gathered, ledto a central gas treatment plant where the gas shall be treated to achieve sales gas quality and

send to the gas pipeline infrastructure at the boundaries of the Disouq Concession.The selected development comprises a central gas treatment site near NSG-1x, where the gasis collected, treated by means of Low Temperature Separation utilizing the Joule Thomsoneffect, and compressed for export. Treated gas is exported via a 16” export pipeline directly intothe GASCO NTS pipeline.

The well fluids from the directly routed wells and the trunk line are fed to a common inletseparator at the central plant. All gases and liquids will be separated and processed on thecentral treatment site into sales gas, stabilized condensate, and free production water.

Treatment of gas is carried out in two trains, while treatment of condensate is in a single train.

Three trains of sales gas compression are installed. During FEED investigation shall clarify, if

the installation of front end booster compressors is more advantageous compared to thisconcept.

Fuel gas for the gas engine drives is taken from the suction of the sales gas compressors.


5/12



Shutdown Philosophy

Page: 5 of 12

To allow further increase of the production additional tailings and all necessary equipment likevalves and flanges shall foresee to allow a simple tie in of future treatment trains.

1.1 Objectives & Scope

This document defines the safety shutdown philosophy and the basis of design for the SafetySystem for Disouq Gas Plant Facility.

The principal objectives of the safety system are:

Ensure personal protection

Minimization of hazards to the environment

Plant and equipment protection

The safety system will provide the safe isolation and depressurization of the total facility orcritical sections of the process and utilities in the event of an emergency condition when thesafety of personnel or equipment is threatened. The safety system is divided into two sub-systems; Fire and Gas detection and protection system (F&G) and Emergency ShutdownSystem (ESD).

This document primarily defines the Process Shutdown philosophy.

Protective systems will provide the protection of personnel, environment, and equipment byproviding the safe shutdown of plant and/or process equipment during an event that mayinclude hazards such as loss of containment or fire, a process upset, or when the primarycontrol system fails to keep the process within specified operating limits.

Shutdown, isolation of process inventories into manageable volumes and depressurizing areused to manage and limit escalation of any event.

Protective systems will include dedicated process sensors and final elements and will not relyupon functions controlled by the process control system. Except where required by the projectdesign specifications, protective system outputs will be designed as Fail-Action, that is, loss ofoutput signal will cause the associated field device to move to its shutdown state.

The Shutdown Philosophy includes systems that respond to different types of events. Thesesystems are the Emergency Shutdown System (ESD) that includes fire and gas detection, firesuppression, and emergency depressurizing, Total Plant Shutdown, Process Shutdown, andEquipment Shutdown.

Electrical protection, including manual emergency switchgear trip, manual emergency generatortrips, and electrical protective relay functions is separate to and independent of the SafetyInstrumented System.

The Shutdown System for each facility will be a self-contained stand-alone system that is notdependent upon inter-location communications. The Shutdown System will operateindependently of the Plant Control System, but communicate with the Plant Control System fordata to be available at the operator interface.


6/12



Shutdown Philosophy

Page: 6 of 12

1.2 Abbreviations

Blowdown valve : BDV

Central treatment Plant : CTP

Emergency Shutdown : ESD

Emergency Shutdown Valve : ESDV

Fire and Gas : F&G

General Process Shutdown : GPSD

Safety Instrumented System : SIS

Safety Instrumented Function : SIF

Process Shutdown : PSD

Safety Integrity Level : SIL

Safety System : SS

Unit Shutdown : USD


7/12



Shutdown Philosophy

Page: 7 of 12

2 Safety Shutdown Philosophy and Principles

2.1. Application

A common safety shutdown system is provided for the entire facility. The shutdown hierarchyapplies across all plant areas.

2.2. Principles

The overall safety shutdown philosophy is based on the principle of maintaining the facility at anacceptable level of safety for personnel; equipment and the environment whilst initiating thelowest shutdown level possible to allow for efficient re-start.

The following principles shall apply to the achievement of an acceptable level of safety:

Personnel safety.

Protect the environment, plant and equipment

Prevent escalation and minimize the consequences of a hazardous event.

Minimize the requirement for manual operations during and after a hazardous event.

Where appropriate, limit cascaded process trips to allow easier identification of the trip

cause and make use of operator intervention.

Provide a system that is simple to implement, test / verify and operate thereby achieving

high availability.

2.3. Applicable Code

API RP 500 Classification of Locations for Electrical Installations

API RP 520 Recommended practice for sizing, selection and installation of

pressure relieving (parts I and II).

API RP 521 Guide for pressure devices in refineries relieving and

depressurizing systems.

2.4. Safety Integrity Level

Safety Instrumented Functions (SIF) within the Protective System will be analyzed to ensurecompliance with the required Safety Integrity Level (SIL) and will be designed to meet the targetSILs of the project.


8/12



Shutdown Philosophy

Page: 8 of 12

3 Logic Hierarchy

The shutdown system logic is structured in a hierarchical form ensuring that an orderlyshutdown of systems can be accomplished. The structure includes:

An Emergency Shutdown System (Level 4) that includes fire or gas detection that initiates

the site emergency alarm isolates the electrical systems and following either confirmed fire

or confirmed gas detection in the processing area initiates a Total Plant Shutdown with

depressurization.

A General Process Shutdown (Level 3) that isolates the site from external sources of

hydrocarbons by closing the facility import and export pipeline valves and inter-facility tie

line valves, isolates large volume inventory, and initiates a process shutdown for train, unit

or process station shutdown.

A Process Shutdown (Level 2) stops a whole process train, closes inventory isolation

valves and initiates Process Equipment Shutdown for the train.

An Equipment (Unit) Shutdown (Level 1) that stops a single equipment item (process

component) and closes its inventory isolating valves.

Figure 1 - Shutdown system logic hierarchy

Total Plant Shutdown, Process Shutdown, and Equipment Shutdown respond to both manuallyinitiated shutdowns from shutdown hand switches, and automatically initiated shutdown fromprocess sensors.


9/12



Shutdown Philosophy

Page: 9 of 12

3.1. Shutdown Levels

The safety shutdown system for the facility is arranged in a hierarchical manner, with each

shutdown level automatically initiating the level below.

The shutdown levels are divided into four (4) main groups, ESD, GPSD, PSD and USD asfollows:

3.1.1 Emergency Shutdown (ESD)

ESD is a high emergency shutdown which will be initiated under extreme circumstances whennormal operations cannot be resumed in the foreseeable future.

ESD shutdown will be initiated by the following conditions:

I. Explosion – identified by operator.

II. Manual fire call point activation.III. Major plant fire, confirmed fire (by at least two detectors) in more than one fire

zone at CTP

The ESD is aimed at isolating hydrocarbon feeds and outlets, reducing hydrocarbon inventoryand limiting ignition sources and will be automatically activate in the following;

Activate the facility emergency alarm

Start fire pumps (where installed)

Activate fire water monitors (where installed)

Initiate fire suppression (where applicable)

De-energize electrical systems

Initiate a Total Plant Shutdown; by closing all SDV’s

Initiate emergency depressurizing at CTP facilities (except well area).

Valves activated upon ESD are identified in the C&E Diagram.

3.1.2 General Process Shutdown (GPSD)

GPSD shutdowns shall be initiated under emergency conditions due to abnormal processconditions not within the limits of process control system, where it is possible that normal

operation could be resumed in the foreseeable future. These conditions are process upsetcircumstances.

Utilities will be kept running as long as possible to enable recovery from the shutdown tripsituation.

The GPSD will be automatically initiated in the following circumstances;

Manual activated switch in the control room or remotely in the CTP.

Shut down of un spared main equipment (such as slug catcher)

Total power failure.

Loss of instrument air pressure. Loss of fuel gas pressure.

High high level in the flare K.O drum.


10/12



Shutdown Philosophy

Page: 10 of 12

This level of shutdown will:

Isolate a site from external hydrocarbon sources by closing the site or facility import and

export pipeline (S) valves that are located at or near the plant area boundary

Isolate a site or facility from external hydrocarbon sources by closing valves on inter-

facility.

Isolate large volume inventory by closing inventory isolation valves

Initiate a Process Shutdown

Initiate Process Equipment Shutdown that is not shutdown by a Process Shutdown

GPSD comprises the activation of all SDVs only. These are identified in the C&E

Diagram.

3.1.3 Process Shutdown (PSD)

PSD is Lower level shutdowns resulting from abnormal process conditions within a definedprocess system.

Shutdown is aimed at avoiding escalation to an emergency condition. Only the train with theabnormality is isolated as well as the electrical system connected to it.

The Process Shutdown provides protection of process units and/or equipment and willshutdown rotating equipment and close equipment shutdown valves. The Process Shutdownminimizes the potential for equipment damage or process excursions.

A Process Shutdown is initiated by:

A manually activated switch in the control room, or field

Automatically by process sensors (pressure, level, temperature)

A Process Shutdown will:

Isolate all trains or units by closing the train or unit isolation valves

Isolate large inventory within trains or units by closing inventory isolation valves

Initiate Process Equipment Shutdown

3.1.4 Equipment/Unit Shutdown (USD)

This level of shutdown is the lowest shutdown level. It results from abnormal process conditionsfor a single equipment/unit only.

Unit shutdown is initiated by:

A Process Equipment Shutdown switch in the control room, or process area

Automatically by process sensors (pressure, level, temperature)

Unit shutdown will activate the followings:

Stop/shutdown a single equipment item or rotating equipment.

Close the process equipment or rotating equipment isolation valves.

Inventory blow down is initiated manually except for incidents for which blow down is

automatic.


11/12



Shutdown Philosophy

Page: 11 of 12

4 Process & Utilities Shutdown Events

The plant flare systems will be designed to handle the plant capacity of 165 MMSCFD based onblocked outlet case resulting from process upset conditions. The flare header is designed for275 MMSCFD to accommodate future expansion expected.

The action of GPSD will reduce the quantity of flared hydrocarbon due to process upsetconditions.

4.1. Abnormal flow

Low flow shutdown inputs should be used for centrifugal pumps to prevent cavitation and

subsequent pump damage from operating at flow rates less than the required minimum

flow. These are not required where pump minimum flow protection is provided.

4.2. Abnormal level

Low low level shutdown inputs are recommended for any vessel where loss of level would

result in damage to process pumps or significant gas blow-by and overpressure of

downstream equipment.

4.3. Abnormal Pressure

Low pressure shutdown inputs should be considered for:

Process equipment that is susceptible to damage in the event of low inlet pressure and no

other adequate protection exists, e.g. compressors. Fuel/pilot gas pressure to shutdown gas engine.

High pressure shutdown inputs and alarms should be considered for compressor

discharge and seal leakage detection systems for pumps.

4.4. Abnormal Temperature

High temperature shutdown inputs and alarms are required for:

Compressor, cooling system, diesel engines and pump lube-oil systems.

Rotating equipment, bearing temperatures.

4.5. Abnormal Vibration

Rotating equipment will be provided with the appropriate vibration protection.

4.6. Utilities Shutdown

All utilities shall be shut down only in case of ESD (level 4) except fire fighting system.

All essential utilities listed below will normally remain in operation.

Instrument Air

Fuel gas system

Fire fighting and deluge systems

Flare System

Open drain & closed drain


12/12

1007 disq 0 p ph 48071 shutdown philosophy

Documents