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7/30/2019 Article Fujairah Uk

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Combined heat & power plant at FUJAIRAH (UAE)for desalinating sea water

By : JC. Gauthier (Head of RnD Dept., PILLARD Marseilles - F)

In 2001, Doosan Heavy Industries & Combustion (South Korea) was awarded the contract for the largest sea waterdesalination plant of the world (1 200 000 people supplied with fresh water, 45 000 m3 per day), located in the FujairahEmirates (U.A.E.). Such a plant uses a combined cycle plant of 660 MW.

The plant comprises 4 gas turbine (GT)/HRSG/ steam turbine units). The HRSGs are equipped for postcombustion.The supply of the postcombustion burners (four x 212 MW units) fuel preparation sets (for natural gas and diesel oil) and theBMS and CCS was awarded by Doosan to PILLARD. It was delivered mid 2002. The starting up with diesel oil was completedin June 2003. Natural gas will only be available in 2004.

1 - POSTCOMBUSTION

The postcombustion burners are of PILLARD GRC INDUCT dual fuel type. They are located downstream of the GTdiverter, at the base of the HRSGs inlet duct.

Main characteristics :

- Gas turbine (GT) : GE FRAME 9 110 MWe

- HRSG : 420 t/h steam at 71 bar/520C

Flue gases to at HRSGs inlet = 840 C (max)

- Turbine exhaust gas (TEG) : Design flow 402 kg/sec at 425C

O2

content = 12,8 to 15,6 % (vol, wet basis)

H2O content = 6,4 to 10,8 % (vol)

- Burners PILLARD : Number = 4

GRC INDUCT type Number of combustion heads per burner = 10, arranged in 2 columns of 5

Fuels = Diesel-oil or natural gas

- Heat release per burner : 120 MW

(without additional air)

- Heat release per burner on TEG : 212 MW i.e. 21,2 MW per burner head

(with additional air)

- Turndown ratio : 1 to 5 per burner head

1 to 50 per burner (of 10 heads)

Fig. 1 : General view


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2 - GUARANTEED EMISSIONS

$ATACONCERNINGTURBINEEMISSIONS

UPSTREAMTOTHEBURNERS

'UARANTEEDEMISSIONS

DOWNSTREAMFROMTHEBURNERS

.!4'!3 $/ .!4'!3 $/

./X PPMVD/

./X PPMVD/

MG.M/

MG.M/

#/ PPMVD/

#/ PPMVD/

MG.M/

MG.M/

We can point out that the burner must not produce any NOx emission (if converted to 15% dO 2).

Fig. 2 : General arrangement of a HRSG

Additionalair fan

postcombustionburner

HRSG

turbine vent(diverter)

stack


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3 - COMBUSTION TECHNIQUE APPLIED

10 PILLARD burners heads GRC INDUCT dual fuel type (patent PILLARD 97/02586) are located in the duct, in 2 columns of 5(Fig. 3, 4).

Each burner head is laterally adjustable in position and removable for maintenance thanks to a system of rails and a side door.The rails are supported by a central pillar (cooled by natural draft) which can be seen in the above. A system of deflectorsallows to adapt and adjust the TEG velocity through the burner.

Such technical solutions aim at obtaining :- A very high flame stability- A low pressure drop (< 30 daPa)- Low NOx and CO emissions.

The Diesel oil atomization is by steam (at 12 bar, 295 C, useful flow 10 % of the D.O. flow). Each diesel oil gun canbe removed from the side of the duct even in operation (Fig. 5). The burner head may continue gas firing during such aremoval.

The corresponding principle is patented by PILLARD (n EU 98430005.3).

Fig. 3 : Positioning of the burner heads in the duct Fig. 4 : Internal view of stage 3, 4 and 5

Fig. 5 : One burner head

Fig. 7 : Internal view : 2 burner heads in operationFig. 6 : External view of stages 1 and 2


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4 - FLOW AND HRSG INLET TEMPERATURE OPTIMIZATION

A modelization thanks to the FLUENT software has been used to improve the velocity distribution through the burner(Fig. 8, 9, 10). Deflectors and a perforated plate have been added. The combustion modelizing allowed to optimize theposition and angle of the burner heads in order to reduce the temperature variation at the HRSG inlet to less than 80C(Fig. 11, 12, 13).

5 - DESIGN OF THE FAILSAFE BMS/CCS SYSTEM

We call the reliability target run-safe. It obliges to master safety as well as availability.

CPU and failsafe I/O cards have been made redundant in order to maintain the required safety level, even in case of a CPUfailure.

The chosen programmable controller (HIMA) is also redundant, and TV approved.

The resistance to high ambient temperature is ensured by the use of military components. It is possible to replace the I/Ocards and CPU whilst energised. The cabinets and flame detection panels have been located inside a marine container closeto the burners and air conditioned. The computing time is reduced in order to comply with the max safety time to close thefuel shut-off valves.

It is possible to operate each unit from its container thanks to an operator interface located on the front face, and to use localpanels for any maintenance operation. However normal operation is achieved from the control room located about onehundred meters from the containers.

Fig. 11 : Temperature field (side view) Fig. 12 : Temperature field(seen from above)

Fig. 13 : Temperature field at HRSG inlet

Fig. 10 : Final resultFig. 9 : Deflectors + perforated plateFig. 8 : Before correction

Fig. 15 : Inside of a containerFig. 14 : View of container


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6 - EMISSIONS AS VERIFIED AT SITE

The emission performances have been verified with Doosan on unit n 1, further to the adjustment of the turbine emissionsthanks to the water injection system.

Line n 1 - August 10th, 2003

Turbine 105,8 MWe on diesel oil (8,33 kg/sec)(with water injection)

4%'ATBURNERINLET#

/ VOLDRY /

VOLDRY $OOSANSGUARANTEE

#/ PPM PPM MG.M MG.M

./X PPM PPM MG.M MG.M

Burner 9 014 kg/hr diesel oil on 10 heads

&LUEGASATSTACK

##

/ VOLDRY /

VOLDRY 0),,!2$GUARANTEE

#/ PPM PPM MG.M MG.M

./X PPM PPM MG.M MG.M

7 - CONCLUSION

The emissions comply with the guaranteed ones :- CO < 50 mg/Nm3 @15%O

2

- NOx < 120 mg/Nm3 @15%O2

with NOx emitted by the turbine complying with the specification.

The NOx emissions due to the burner are lower than those of the turbine : The mass flow of NOx is reduced by 10 to20 % thanks to the reburning effect.

Such a plant confirms the reliability of the GRC INDUCT dual fuel burners as well as the possibility to use them for dieseloil firing at a high heat release rate with short flames and with a homogeneous temperature distribution at the HRSG inletwithout hot spot points.

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