1c_process_operation_system.ppt

8/10/2019 1c_process_operation_system.ppt

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PLANT OPERATION SYSTEM

Dr. AA

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PROCESS SYSTEMType of process equipments etc is dependent on the processitself.

Lets take Oil Platform and an example

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The heart of Process System is the Distributed Control System(DCS)


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Oil and Gas Production Overview

The figure gives a simplifiedoverview of the typical oil andgas production process

Products from wellhead feedinto production and testmanifolds.

The remainder of the figure isthe actual process, called theGas Oil Separation Plant(GOSP).

While there are oil or gas onlyinstallations, the wellstream will

consist of a full range ofhydrocarbons from gas(methane, butane, propaneetc.), condensates (mediumdensity hydro-carbons) to crudeoil.

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Oil & Gas Block Diagram

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Wellhead

First Stage

Separator

Second StageSeparator

Gas

Treatment

Oil

Gas

Water

Gas

Treatment

Third Stage

Separator

Coalescer

Oil

Water

Gas

Water

Treatment

System

Oil Export

Terminal

Gas

Export

Fuel Gas

System

Flare

Note: In Some cases,

all gases go to flare


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Oil and Gas Process

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Typical Objectives of Plant Operation

1. Protect people

2. Protect Environment

3. Protect Equipment

4. Maintain Smooth operation

5. Achieve Product rates and quality

6. Profit = optimising first five

7. Monitoring & diagnosis

These are Achieved Through Process Control

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DCS Architecture

Process Transmitters and Actuators

Data Highway

(Shared Communication Facilities)

......

Data

Storage Unit

Host

Computer

System

ConsolesPLC

4-20 mA

LocalConsole

Local

ControlUnit

4-20 mA

Local

ControlUnit

LocalConsole

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Fieldbus Technology

Introduced 1988 but underwent

many development Standard IEC61158 introduced in

1999

Based upon smart valves, smartsensors and controllers installed inthe field.

Uses data highway to replacewires from sensor to DCS and tothe control valves.

Less expensive installations andbetter reliability.

Can mix different sources(vendors) of sensors, transmitters,and control valves.

Now commercially available andshould begin to replace DCSs.

CEAG

I/O

P5001 0... 150 bar

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Foundation Fieldbus (FF)

Profibus (Process Field Bus)

Others: ControlNet, P-Net, SwiftNet ,

WorldFIP, Interbus, EtherCAT,

SERCODS etc


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Fieldbus Architecture

Plant Optimization

.................

Smart

Sensors

Smart Control

Valves and

Controllers

Local

Area

Network

Smart

Sensors

Smart Control

Valves and

Controllers

Local

Area

Network

H1 Fieldbus NetworkH1 Fieldbus Network

H1 Fieldbus H1 Fieldbus

Data Storage

PLCs

High Speed Ethernet

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PLC Architecture

ProcessorPowerSupply

Data Highway

PLC Cabinet

ProgrammingInterface

I/O Modules

Input

Devices

Output

Devices

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We desire independent protection layers, withoutcommon-cause failures - Separate systems

sensors

SIS system

i/o i/o.

sensors

Digital control system

i/o i/o.

DCS handles controls

and alarms functions.

PLC handles SIS and

Alarms associated with SIS

Redundancy

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UTILITIES SYSTEM

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Water Treatment

When the water cut is high, there will

be a huge amount of produced water.A water cut of 40% gives a waterproduction of about 4000m3per day(4 million liters) that must be cleanedbefore discharge to sea.

Often this water contains sand

particles bound to the oil/wateremulsion.

The environmental regulations limitsoil in water discharged to sea to 40mg/liter (ppm).

It also places limits other forms ofcontaminants.

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Water Systems

Potable Water

For larger facilities, potable water is provided onsite by desalination of seawater thoughdistillation/reverse osmosis.

Seawater

Seawater is used for cooling purposes to AirCompressor Coolers, Gas Coolers, Main

Generators and HVAC.Also used for production of hypochlorite and forFire Water.

Seawater is treated with hypochlorite to preventmicrobiological growth in process equipment andpiping.

Ballast Water

Ballast systems are found on drilling rigs, floatingproduction ships and rigs as well as TLP (tensionleg platforms). The object is to keep the platformlevel and at a certain depth under varyingconditions.

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Flare and Atmospheric Ventilation

The purpose of the Flare andVent Systems is to providesafe discharge and disposalof gases and liquids

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Flare System

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Accumulation of gas/liquid from:

Spill-off flaring from the product

stabilisation system. (Oil,

Condensate etc.).

Production testing

Relief of excess pressure caused

by process upset conditions and

thermal expansion.

Depressurisation either in

response to an emergencysituation or as part of a normal

procedure.

Planned depressurisation of

subsea production flowlines and

export pipelines


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HVAC

The Heat, Ventilation and Air-Conditioning system (HVAC) feedsconditioned air to the equipment rooms, accommodations etc.

Cooling and heating is achieved by way of water cooled or water/steamheated heat exchangers.

Heat may also be taken off gas turbine exhaust. In tropic and sub-tropic

areas, the cooling is achieved by compressor refrigeration units. Also, intropical areas gas turbine inlet air must be cooled to achieve sufficientefficiency and performance.

The HVAC system is usually delivered as one package, and may alsoinclude air emissions cleaning.

Some HVAC subsystems include: Cool: Cooling Medium, Refrigeration System, Freezing System

Heat: Heat medium system, Hot Oil System.

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Chemicals and Additives

A wide range of chemical additives are used in the main process.

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Chemicals Functions

Scale inhibitor The scale inhibitor will prevent the contaminants from

separating out. Scale or sediment inhibitor is added on

wellheads and production equipment.

Emulsion breaker An emulsion breaker is added to prevent formation of, andbreak down of the emulsion

layer by causing the droplets to merge and grow.

Antifoam Polyelectrolyte is added before the hydrocyclones and

causes oil droplets to merge.

Methanol (MEG) Methanol or Mono Ethylene Glycol (MEG) is injected

inflowlines to prevent Hydrate formation and preventcorrosion.

TEG Tri Ethylene Glycol (TEG) is used to dry gas.

Corrosion Inhibitor injected in the export pipelines and storage tanks to prevent

corrosion


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Telecommunication Systems

Public Address & Alarm System/F&G Integration

Drillers talk back System UHF Radio Network System

Closed Circuit TV System

Mandatory Radio System

Security Access Control

Meteorological System/Sea Wave Radar

Telecom Antenna Tower and Antennas

PABX Telephone System

Marine Radar & Vessel Movement System

Office Data Network and Computer System

Personnel Paging System

Platform Personnel Registration and Tracking System

Telecom Maintenance and Monitoring System

Ship Communication System/PABX Extension

Radio Link Backup System

Mux and Fiber optical Terminal Equipment11/19/201420

Documents

1c_process_operation_system.ppt