05-3909-00-H-3-003- Rev A

FEED FOR SHUWEIHAT PHASE 3 (S3) GAS SUPPLY CUSTODY METERING SYSTEM

OPERATION AND CONTROL PHILOSOPHY

Doc. Reference 05-3909-00-H-3-003 Rev A Page 1 of 10


15/12/2011 A ISSUED FOR REVIEW RC KA JM

Date Revision Description of Revision Prepared Checked Approved




TABLE OF CONTENTS

1 INTRODUCTION 3

1.1 Project Overview................................................................................................................31.2 Scope of Document............................................................................................................31.3 Acronyms and Abbreviations..............................................................................................31.4 Reference Documents........................................................................................................4

2 METEOROLOGICAL DATA 4

3 PROCESS DESIGN DATA 5

3.1 Process Description............................................................................................................53.2 Gas composition and Gas flow rates..................................................................................5

4 GENERAL PHILOSOPHY 5

4.1 Motor operated valve..........................................................................................................54.2 Gas Separator (Cyclone)....................................................................................................64.3 Gas Filters.......................................................................................................................... 64.4 Custody Metering System..................................................................................................64.5 Remote Terminal Unit (RTU)..............................................................................................74.6 SMC System...................................................................................................................... 74.7 Power Supply..................................................................................................................... 74.8 Fire and Gas System..........................................................................................................8

5 OPERATION AND CONTROL PHILOSOPHY 8

5.1 General............................................................................................................................... 85.2 Facility at Shuweihat Phase 3 gas supply metering system...............................................85.3 Start up and Shutdown.....................................................................................................105.4 Purging Requirement........................................................................................................10




1 INTRODUCTION

1.1 Project Overview

Abu Dhabi Gas Industries Ltd (GASCO) intends to supply sales gas to ADWEC new power station Shuweihat Phase 3 in January 2013 in Shuweihat area with a dedicated custody metering system.

As a part of this project, a new Separation and Filtration System (1W+1S), dedicated custody meter and proving meter and its integration with the Pipelines Supervisory monitoring and control system is envisaged.

The interim source of gas supply will be from existing Ruwais-Shuweihat Gas pipeline project (5209) tie-in point downstream of existing MOV 815 and will utilize HRS project (032086) Tie-in point downstream of MOV 314 for permanent continuous gas supply to Shuweihat Phase 3 Power plant.

1.2 Scope of Document

The purpose of this document is to describe operation and control philosophy to provide safe and reliable operations of pipelines and associated equipments to the new facility.

1.3 Acronyms and Abbreviations

API American Petroleum Institute

CRS Consumer Receipt Station

ESD Emergency Shutdown

MOV Motor Operated Valve

FEED Front End Engineering & Design

HSE Health Safety and Environment

RTU Remote Terminal Unit

SOW Scope of Work

WT Wall Thickness

NOC No Objection Certificate

LO Lock Open

LC Lock Close

PSV Pressure Safety Valve

TP Tie in Point

FSD Fail Safe Design




1.4 Reference Documents

Document Number Document Name

05-3909-00-H-0-001 Process Flow diagram for Shuweihat Phase 3 gas supply

metering skid.

05-3909-00-H-0-002 P&ID-Legend sheet for Shuweihat Phase 3 gas supply

metering skid.

05-3909-00-H-0-003 P&ID- Gas separator for Shuweihat Phase 3 gas supply

metering skid.

05-3909-00-H-0-004 P&ID- Gas Filters for Shuweihat Phase 3 gas supply

metering skid.

05-3909-00-H-0-005 P&ID- Gas supply flow metering skid for Shuweihat Phase

3 gas supply metering skid.

05-3909-00-H-4-001 Process Design Basis for Shuweihat Phase 3 gas supply

metering skid.

2 METEOROLOGICAL DATA

Piping design shall be in accordance with following ambient conditions:

Maximum temperature: 60 ° C (dry bulb)

Minimum temperature: 5 ° C (dry bulb)

Summer average temperature: 35 ° C

Winter average temperature: 22 ° C

Solar radiation temperature: 85 ° C

Earthquake: Zone: HOLD

Rainfall (Maximum): HOLD

Rainfall (Minimum): HOLD

Rainfall Frequency: HOLD

Dew: HOLD

Maximum Wind speed: HOLD

Soil condition: HOLD

Type: Arid, mostly sand, loose to medium density, generally avoidable for Vegetation

Features: Desert Area




3 PROCESS DESIGN DATA

3.1 Process Description

Shuweihat consumer receipt station (CRS-710) presently is feeding Shuweihat Phase 1 and 2 consumers. This facility comprises of scrapper receiver, a set of filters, metering skid and a provision for PRS (Pressure Reducing Station). A provision is kept with isolation valve MOV-815(20”) to feed Shuweihat phase 3 consumer requirements. A new 48” pipeline from HRS project shall continue constant gas supply to phase-3 consumer. This is recently awarded to EPC and expected to be completed by Q3, 2013. The two main piping in Shuweihat New Phase 3 consumer facility are:

42” pipeline tie in from existing Phase-1 & 2 facilities to new Phase-3 facility after MOV-815. (TP-02)

48” pipeline tie in from new HRS project to new Phase-3 facility after MOV-314.(TP-01)

Tie in to new Phase 3 facility from existing facility from Phase 1 & 2 is already having filtration system to provide clean sales gas supply to consumers, but it recently encountered a problem of black particle contamination in the system. New HRS pipeline system shall comprise of new black particle separation and filtration system and custody metering station (Z configuration with proving meter). In order to supply uninterrupted clean sales gas supply to power plant at Shuweihat Phase-3, both tie in, after MOV-815 (existing Phase 1 & 2 tie in) and MOV-314 (New HRS tie in) shall be joining together at upstream of new particle separation, filtration system and custody metering station.

Existing facility from phase 1 & 2 shall continue sales gas supply to Phase 3 consumer up to Q3 of 2013. After this time, the line shall be lock closed permanently to avoid any backflow from HRS 48” new piping. Preferably a removable spool pipe piece shall be used to avoid the back flow. After Q3 of 2013 when HRS will be started, HRS facility will be continuing sales gas supply. Entire system shall be designed based on 460 MMSCFD design capacity.

3.2 Gas composition and Gas flow rates

For Natural Gas composition and flow rate and properties please refer document 05-3909-00-H-4-001-Process Design Basis for Shuweihat Phase 3 Gas Supply Custody Metering Skid.

4 GENERAL PHILOSOPHY

4.1 Motor operated valve

All valve 20” and above size shall be motor operated (MOV). MOV shall be provided at following location for operational requirement

1. Inlet of gas transfer line

2. Inlet of gas separator

3. Outlet of gas separator

4. Inlet and bypass of gas filters

5. Inlet / outlet of gas metering skid




All MOV shall be capable of being operated remotely (from Maqta / Habshan) as well as locally. All MOV open and close status shall be communicated to Maqta / Habshan main control room via RTU. All MOV must have supplementary hand-wheel in case of emergency operation. Hand wheel shall be mechanically independent of motor. All 20” and above size MOV shall be gear operated.

4.2 Gas Separator (Cyclone)

The new system is to handle dry natural gas and is not expected to carry any liquids. Separator shall be used to handle black carbon particle, dust and other particulates etc picked up by gas during its transportation through pipeline. One working and one standby 2 X 100% cyclones shall be sized for the maximum design flow rate. MOVs are used at inlet and outlet of gas separator to provide positive isolation. MOVs for working gas separator shall be in “LO” lock open position and for standby in “LC” lock close position. MOVs shall be operated locally; open/close status of MOV shall be communicated to main control room at Maqta /Habshan (SMC system) via new RTU (to be confirmed later). Each Gas separator shall be designed 100% to remove 99.9% of solid particulates up to size 5 micron.

4.3 Gas Filters

Most of the particles above and up to 5 micron size shall be removed in gas separators. The remaining dust particles carried to the downstream of gas separator shall be filtered using 1W+1S 2x100% gas filters. Filter shall have automatic changeover facility. MOV’s are used at inlet and bypass of gas filters. MOVs shall be capable of operating remotely through pressure differential alarm as well as locally. All MOV open and close status shall be communicated to Maqta / Habshan control room via RTU. Each filter unit shall be designed 100% to remove 99.9% of solid particulates up to size 2 micron.

4.4 Custody Metering System

The New Custody Transfer Metering Skid shall be located at downstream of new filtration system (Gas cyclone plus Gas filter). The metering skid shall be in 2-stream X 100% (1-working & 1-standby), Z-type configuration (pay & check), 32” inlet/outlet pipe diameter (Size to be confirmed later), and utilizing digital multi-path (4-6 path), ultrasonic type flow transmitter. It shall be designed for a design pressure of 63.5 barg with minimum and maximum flow rate of 100 MMSCFD (value will be confirmed based on consumer end minimum flow requirement) /460 MMSCFD respectively. However range shall be 1-100%. Accuracy shall be +/- 0.25 % or better as per AGA-9.

The metering skid shall be sized and designed based on the Process design parameters as per Process Design Basis, Document Number: 05-3909-00-H-4-001.

The main components of the metering skid shall comprise but not limited to the following:

1. Analyzer (Online Process Gas Chromatograph, 1 online and 1 stand by)

2. Motor Operated Valves (MOV)

3. Flow Conditioner / straightening vane

4. Upstream section, 10D of pipe size up to primary device. The inlet side shall be welded and the outlet side shall be flanged to the meter tube.

5. Redundant Ultrasonic Flow Transmitters, multi-path with +/-0.25% accuracy or better as per AGA-09.




6. Downstream section, 5D of pipe size. The inlet shall be flanged to meter tube and the outlet shall be welded.

7. The flow computers (2 nos.) shall form part of custody metering package. Pressure Transmitter, Pressure Gauge, Temperature Transmitter, Temperature Gauge and skid mounted junction boxes shall be provided as a minimum. Any other items as shown in the P&ID shall be provided with the metering skid package as minimum.

8. The flow computer shall be installed in a dedicated cabinet supplied by vendor, equipped with redundant PLC and redundant supervisory computer system (as minimum). Supply shall include all necessary configuration i.e applicable software, required cabinet components, accessories etc. All Custody Metering System data and reports shall be communicated to existing supervisory computer (SMC) system at Maqta / Habshan control room via RTU communication through redundant serial link using modbus protocol.

9. All required piping accessories, i.e. vents, isolation valves, drains, etc as shown in P&ID shall be provided as minimum.

10. One (1) hand held HART communicator for all SMART transmitters.

MOV shall be used at inlet and outlet of custody metering skid. Inlet MOV shall be operated locally. Metering skid outlet MOV shall be capable of being operated locally and remotely (By Supervisory Computer System). All MOV status shall be communicated to RTU via serial link using modbus protocol. RTU shall communicate these indications to existing SMC system at Maqta / Habshan main control room.

Skid piping specification shall be as per Addendum to onsite Non piggable Piping Material. Document Number- 05-3909-00-L-1-003.

For Custody Metering specification, refer Document No. 05-3909-00-I-1-005.

4.5 Remote Terminal Unit (RTU)

New RTUs (On HOLD) shall be installed for New Shuweihat Phase 3 (S3) gas supply system. All field instruments (Except for Custody Metering Skid Mounted instruments) and MOVs on this project shall be connected and interfaced with RTU. All Custody metering system data and signal shall be communicated as mentioned in section 4.4 of this document.

RTU shall communicate all aforesaid signals and data to existing SMC system at Maqta / Habshan main control room for a real time remote monitoring and control via existing telephone leased lines at Shuweihat Plant.

RTU shall be a PLC based microprocessor and shall provide all logics necessary for the operation and control requirement of the project.

4.6 SMC System

New Custody Metering System, Filtration system and F&G system for New Shuweihat Phase 3 (S3) gas supply system shall be monitored and controlled at Habshan and Maqta main control room through existing SMC system via RTU installed in Shuweihat Plant. A real time data communication shall be provided and ensured between RTU and SMC system. Alarm database, graphic displays & control configuration for this project shall be provided at existing SMC system at Maqta / Habshan control room.

4.7 Power Supply




240 V, 50 HZ AC power supply to all MOV shall be made available from respective substation.

4.8 Fire and Gas System

Fire and Gas system shall be provided in new Shuweihat Phase 3 gas supply system. The following type of detectors shall be used

Flammable gas detectors

Toxic gas detectors

Flame detectors

Fire and toxic, flammable gas alarm shall be communicated by existing F&G panel (On HOLD) to RTU. RTU shall communicate these signals/alarms to existing SMC system at main control room at Maqta / Habshan.

5 OPERATION AND CONTROL PHILOSOPHY

5.1 General

New natural gas supply pipeline system shall be safe and reliable to supply natural gas to Shuweihat Phase 3 new consumers - ADWEC power plant. System shall be monitored from existing control room at Habshan and Maqta. Inlet arrival pressure, custody flow, supply pressure to consumer end and temperature are measured and transmitted through RTU to main control room at Habshan and Maqta.

5.2 Facility at Shuweihat Phase 3 gas supply metering system

Shuweihat phase 3 gas supply system shall comprise of the following

New piping from existing Phase 1 & 2 facility / HRS tie in

Gas separator (Cyclone)

Gas filters

Custody metering skid

Associated instruments

Fire and Gas detectors

New piping from existing phase 1 & 2 facility / HRS tie in

New piping in phase 3 (S3) facility shall have an MOV at inlet to ensure gas supply into the system. Open and close status of MOV shall be monitored through RTU and shall be transmitted to main control room at Habshan / Maqta. Pipeline tie-in from existing Phase 1 & 2 facility shall supply sales gas initially when HRS is not commissioned. It shall continue gas supply till Q3, 2013. After Q3 this line shall be permanently closed and new HRS tie in shall supply sales gas to the system. Tie-in from existing Phase 1 & 2 facility to new Phase 3 facility shall be with a removable spool so that positive isolation can be ensured when new HRS project is commissioned.




An MOV shall also be provided at HRS pipeline tie-in inlet to ensure supply of gas. Open and close status of MOV shall be monitored through RTU and shall be transmitted to main control room at Habshan / Maqta.

Gas separator (Cyclone)

Two number of cyclone gas separators shall be installed to remove black powder particles and other dirt and dust which are picked up during gas transportation in the pipeline. Cyclones shall remove particulates up to 5 micron size. These shall be sized for maximum design flow of 460 MMSCFD with 2x100% capacity, one in operation and other in standby. MOVs are provided at individual inlet /outlet of cyclone separator. All MOVs in operating unit shall be “LO” and in standby unit “LC”. These MOVs shall be capable of operating locally, open and close status of MOV shall be monitored continuously through RTU.

Gas filters

To remove particulates less than 5 micron and up to 2 micron, a set of gas filters shall be provided at downstream of cyclone separator. Filters shall also be sized for maximum design flow rate of 460 MMSCFD at 2x100% capacity. Differential pressure across filter bed shall be monitored continuously through RTU and transmitted to main control room at Habshan / Maqta to enable an alarm in SMC system and to indicate requirement of filter changeover. Filter shall have automatic changeover facility based on differential pressure. MOVs are provided at inlet of each filter (one working & one standby) and MOV open and close status is monitored through RTU. In case of high differential pressure across operating filter bed, MOV at filter inlet shall be closed and MOV at filter bypass line shall be opened. This shall open MOV at standby filter inlet. In case the working filter is clogged, bypass MOV is open but if stand-by filter inlet MOV is not available or not working, the operator must ensure to open bypass throttling valve to ensure gas supply at downstream to stand-by filter. The configuration offers flexibility and ensures constant clean gas supply at consumer end.

Custody metering skid

Sales gas is supplied to consumer at Phase 3 through a custody metering skid installed at downstream of gas filters. Metering skid facility shall have two ultrasonic flow meters (each sized for design flow rate) in Z configuration with pressure and temperature compensation. Flow meter output shall be connected to flow computer located in existing control room at Shuweihat Plant. All Custody Metering System operation shall be facilitated by a dedicated Supervisory Computer System. Supervisory Computer System shall consist of redundant flow computers, redundant PLC and redundant supervisory computers. The Supervisory Computer System shall communicate all data, reports to RTU via redundant serial link using modbus protocol.

Online gas chromatograph (with 100% redundancy) shall be installed at upstream of flow element which will be connected to the flow computers to measure the flow.

During normal operation gas flow passes through one meter and flow parameters are obtained, monitored and recorded. Interconnecting line between two flow meters is provided with an isolation ball valve which is normally closed during normal operation. For proving operation, isolation MOV at downstream of standby flow meter is opened first. Then isolation MOV at interconnecting proving line shall be opened, this allows gas flow to be routed from duty main stream to proving




stream. Hence, flow data is obtained simultaneously from both streams and compared.

This dual arrangement provides “standby / redundant metering option”. In case main duty stream fails to give accurate flow measurement by erratic signal and /or requires any maintenance, standby stream can be taken into operation.

MOV are provided at inlet / outlet of flow metering skid for local and remote operation with open and close position indication in supervisory computer system and finally in SMC at Habshan & Maqta main control room through RTU.

Fire and Gas detectors

Flammable, toxic gas and flame detectors shall be installed at CRS including separator, filtration unit and metering skid. Signals from this flame, toxic and flammable gas detector shall be communicated to respective RTU by existing F&G panel (To be confirmed later) and transmitted to main control room at Habshan / Maqta. Audible and visual alarm shall be provided to approach operating personnel. Audible alarm shall be in timer for remote areas and visual alarms shall stay on unless abnormal condition is attended / resolved and system is reset to normal condition.

5.3 Start up and Shutdown

Normal start up

After pre-commissioning of new piping, piping shall be pressurized using bypass line of inlet MOV and pressure shall be constantly monitored. Once pressure is equalized at upstream and downstream, MOV in line shall be opened fully. All MOVs in operating filter unit shall be in “LO” (lock open) position. Status of MOVs open and closure position shall be monitored through RTU.

Normal shutdown

At any point pipeline can be isolated by closing MOV at inlet line which can be initiated from field through local hand switch. After shutdown, piping component and equipments shall be depressurized. Depressurization can be up to atmospheric as per maintenance requirement of equipments (i.e gas separators and filters). This shall be in consultation with package vendor.

Emergency Shutdown

In case of any emergency, shutdown can be taken into place by remotely closing MOVs provided at inlet and outlet of the facility. Remote closing can be performed from main control room at Habshan / Maqta. After shutdown, piping component and equipments shall be depressurized. Depressurization can be up to atmospheric as per maintenance requirement of equipments (i.e gas separators and filters). This shall be in consultation with package vendor.

5.4 Purging Requirement

After shutdown, Gas Filters and Flow meters shall be Nitrogen purged for further clean up. For Gas filters, 2” connection with isolation ball valve is provided for purging. This shall be performed as per requirement using portable Nitrogen cylinder at site. If in any case master flow meter of gas metering skid is required to be taken in to maintenance then also that isolated portion of piping shall be purged with nitrogen using 2” purging connection.