NGL recovery from fuel gas

at Safaniya + Tanajib

by JT Expansion Valve

Otis Armstrong– 02 Nov. 2009

(analysis by Twister BV & P&CSD)

• Background & Technical –SA interest in JT expansion for Economics to apply to

Fuel Gas of TPD & SONPD

• Why? Apply to Saf & Tan Fuel Gas – no deep recovery of condensate in gas

55F dew point vs -32F dew Point by JT

• Design approach -Use PFD Composition + sensitivity from Labs results

• Tanajib vs. Safaniyah – same fuel composition with new FG line, diff P&T

• Economic analysis –Results SONPD higher IRR due to bigger gas use & no line dp

Agenda

HOW? JT Valve = Min stages to Max Vena Cava +meet noise dB

Single stage

deviceMulti stage device

Expansion at ~S=C

Recovery at ~P=C

Intersection ~= max JT

Twister technology

Reduces valve

friction heating to

increase cooling &

NGL recovery.

H-S valve analysis

does not account

for friction heating

in gas flow

OP Armstrong 2009

Condensate Recovery module = Goal for our application- LSTK

• Objective : Recover valuable C3+ hydrocarbon NGL’s from boilers & furnaces fuel gas at Tanajib &Safaniya by LTX gas expansion using Twister Technology

• Sweet fuel gas for Tanajib originates from Safaniya- identical composition, but flow rate, inlet P & T are not identical- system drawing

• Sufficient pressure drop available for expansion (~90%) in both Twister LTX application’s

• Gas is dehydrated to 7 lb/MMSCF

• Cool gas in gas-gas heat exchanger(s) to increase condensate recovery

• Configuration with only 1 JTX valve or Twister selected at both location

• Apply maximum heat integration; use MEG when Low T Separator temperature is below Hydrate Forming Temperature

• Hydrocarbon Condensate goes into condensate line by independent pump

Design approach for Tanajib & Safaniyah JT LTX Application

PFD – Safaniya EXISTING FUEL SYSTEM w/o JT bypass

12”FG-4 to SEC

8“-P-222 (FG frm Refrig)

P/L Comp’s

PCV107 A/B

12“-FG-5

Hot oil furnace

Flare, Purge &Misc. users

Glycol Heater &Purge

Boilers

Sweet gas from Refr

PCV104 A/B

Co

nd

ensa

te 1

0”P

25

3

36“-P-230 (FG frm P/L K’s)

6“-FG-3/4

Point A

Point C

Point B

PFD – Safaniya F/G w/ JT By-Pass System INSTALLED

12”FG-4 to SEC

8“-P-222 (FG frm Refrig)

P/L Comp’s

PCV107 A/B

12“-FG-5

Hot oil furnace

Flare, Purge &Misc. users

Glycol Heater &Purge

Boilers

Sweet gas from Refr

PCV104 A/B

36“-P-230 (FG frm P/L K’s)

6“-FG-3/4

JT Unit

Hea

vy F

uel

Gas

Ligh

t Fu

el G

asCondensate out

Point A

Point B

Co

nd

ensa

te 1

0”P

25

3

Point C

JT

PFD – Safaniya Twister LTX PFD Internal Configuration

PFD – Tanajib EXISTING Fuel Gas System w/o LTX bypass

Sour gas from Offshore gas pipeline 8“-FG-600-9A2L

ZV1507

G82-D-090

PCV1512 A/B

G82-D-091

PCV1516 A/B

12“-FG-610-3A1L

Hot oil furnaceG80-F010/011

Flare, Purge &

Misc. users (G80)

Glycol Heater &Purge (G54)

BoilersG80-F007/008

Sweet gas fromSafaniya (new)

NC

Co

nd

ensa

te

Point C

Point B

Point A

PFD – Tanajib F/G with LTX Twister By-Pass INSTALLED

Sour gas from Offshore gas pipeline

Sweet gas fromSafaniya (new)

8“-FG-600-9A2L

ZV1507

G82-D-090

PCV1512 A/B

G82-D-091

PCV1516 A/B

12“-FG-610-3A1L

Hot oil furnaceG80-F010/011

Flare, Purge &Misc. users (G80)

Glycol Heater &Purge (G54)

BoilersG80-F007/008

LTX Unit

He

avy

Fuel

Gas

Light Fu

el Gas

Co

nd

ensa

te

Condensate out

Existing

New

NC

Point A

Point B

Point C

PFD – Tanajib Twister LTX Internal PFD

JT

C3+ recovery

summer winter

Safaniya 875 bpd 1032 bpd

Tanajib: 535 bpd 475 bpd

Total 1410 bpd 1507 bpd

Liquid recoveries by Twister using PFD Compositions

• LPG 25 US$/bbl

• C5+ 35 US$/bbl

• Fuel gas 3.3 US$/MMBTU

• Electricity 3 ct/kWhr

• MEG 5,000 US$/metric tonne

• Inflation 5% per year

• NPV discount rate 15% per year

• Maintenance 250,000 per 3 years

• Operating days 350 days per year

• Lifetime 20 years

• Apply gas shrinkage for constant BTU to gas system

Economic analysis - parameters

Safaniya: MMBTU/d constant

Total installed cost US$ 10,000,000

NPV net profits US$ 24,260,000

IRR 49.1%

Tanajib:

Total installed cost US$ 9,000,000

NPV net profits US$ 9,500,000

IRR 31.3%

Economic analysis – results (nearly identical CAPX but SONPD higher gas demand)

1. Some Gas analysis have indicated that the gas is much

dryer than 7 lb/MMSCF. This means possible operation w/o

chemicals thus reducing OPEX.

2. Black powder in Gas line also indicates intermittent off-spec

operation

3. Chemical free operation is possible by maintaining the LTS

temperature above the hydrate formation temperature

4. Chemical free operation is also possible by using a hydrate

separator (Twister BV proprietary technology) which uses

hot oil/hot water to melt hydrates inside the vessel

4. Conservative gas shrinkage case taken as base case

Economic Analysis - sensitivities

• ___________________ Conclusion______________________

• OP Armstrong’s claim is substantiated by P&CSD review to extract

substantial amounts of NGL ’s from fuel gas at both Safaniya and

Tanajib by LTX Twister with Gas to Gas LTX cooling

• Economic analysis indicates both locations provide a positive

income & high IRR

• Maximum profits can be obtained by maximising heat integration

and using MEG only when required

__________________Action Recommended__________________

• Install 1st Unit at SONPD due to higher IRR, but also for Tanajib

• Submittal was made to P&CSD and Concurred for Application

• Make Request to Facility Planning for Formal DBSP, pending

Management approval. FPD to review economic alternatives.

Conclusions & Recommendations

Salient Points of P&CSD Evaluation, emails dated 10/3&7 of ‘09

The LTS liquids from the Twister and J-T systems are compared as follows:

SUMMER CONDITIONS Proposed Twister System

Conventional J-T Expansion

Raw Fuel Gas, MMSCFD 27.98 27.98Inlet Pressure, psia 997 997Inlet Temperature, °F 140 140

Fuel Gas Pressure, psig 85 85

LTS Liquids Flow, Std BPD 1292 1295

addition of Twister technology does not offer any significant advantage ... Therefore, for the Safaniyah application, addition of

proprietary Twister system to recover heavier condensate from rich fuel gases cannot be recommended.

Regarding

the need to

recover

higher-value

hydrocarbon

s from fuel

gas, yes that

should be

considered

on its own

economics.

Perhaps that

should have

been done

long time

ago, and that

remains true

wherever

rich gases

are

consumed

as fuel.

Overview of Safaniyah area Flow Lines

Overview of Twister LTX Swirl ValveTwister’s field experience with Swirl Valve as JT Choke for LTX shows :

HC dew-point reduced by 7°C at design capacity.

Flow rate increases 20% from capacity with conventional JT choke

Cold separator temperature increases by 5°C,

Pressure drop over conventional JT valve is reduced by 20%

A safe Noise level of 70dB(A) at design capacity.

It Provides linear control characteristic like other traditional cage valves

Swirl Valve Working Principle :

Compared to a traditional valve, the SWIRL Valve enlarges the mean diameter of droplets

and bubbles by at least a factor of 5. Only droplets with a diameter smaller than 0.2 micron

will not be separated by the SWIRL Valve. A SWIRL Valve works using Tangential slots in the

cage valve trim to force the liquid flow into a strong rotational motion, causing small droplets

to concentrate and agglomerate along the perimeter of the pipe wall. Free pressure energy is

dissipated through dampening of vortex along the extended pipe length downstream of the

valve. Advantage of creating a swirling flow in the valve is twofold: 1. Regular velocity

pattern provides less interfacial shear meaning less droplet break-up resulting in larger

drops, then concentrating the droplets in circumference of the flow area to increased number

density giving improved coalescence from larger drops. The flow is normally throttled over a

perforated cylinder (cage). These perforations, either slots or holes have a radial orientation

perpendicular to the cylinder surface. Dissipation of energy by centrifugal forces produces

useful work as opposed to conventional valve energy dissipation via eddy currents which

produce no useful work.

Overview of Twister LTX Swirl Valve

Overview of Twister

ProcessTwister Supersonic Separator works by taking

in a feed of saturated ('dirty') gas, and then

using available pressure drop to expand pre-

swirled gas via a Laval nozzle (contracting and

then widening pipe throat) which accelerates

the gas to supersonic velocities . The cooling

effect of this expansion forces the water and

hydrocarbons to condense forming tiny droplets

which are then efficiently separated from the

gas using the high centrifugal forces(500,000g)

caused by the rotating vortex (conservation of

angular momentum – angular velocities

increase in direct proportion to the reducing

diameter of the tube inner body - like a figure

skater spinning). The Static inlet guide vanes

twist the gas, and it moves through the Twister

tube at over Mach 1, while swirling around in a

vortex fashion.

Droplets are thrown to the outside of the tube,

where they are removed from the processed

gas using a simple pipe-in-pipe separator and

some of the process gas (slip gas) as a carrier

The gas that flows straight through the tube is

conditioned, with impurities removed

Detailed

Engineering

should review

merits of a

conventional

Twister Tube as

opposed to the

JT Twister valve.

The Twister

personnel claim

deeper recovery

is possible in a

twister tube due

to the

supersonic

effect imposed

on a gas by a

true Twister

tube. The issue

is does the

additional cost

justify use of the

twister tube as

opposed to

Twister JTX

valve?