HVAC | Flash Gas Compressor Barges
AKCO awarded a letter of intent to the consortium of Single Buoy Moorings Inc. (SBM) and Siemens on 29th July 2004, followed by a contract award on 30th September 2004 for the Design, Engineering, Procurement and Fabrication (EPF) of three Flash Gas Compressor Barges (FGCB) 3, 4 and 16 to be used for the Kashagan Field Development in the northern part of the Caspian Sea offshore Kazakhstan. SBM commissioned shipyard Lamprell in Dubai to build the FGCBs.
The Kashagan oil field
The Kashagan oil field in the northern Caspian Sea off the coast of Kazakhstan is reported to be one of the largest fields discovered in the past 30 years. With recoverable reserves of up to 13 Bbbl, it offers a tremendous opportunity for the petroleum industry.
At the same time, the Kashagan field presents a wide range of environmental, geographical and technical challenges. A major concern of project developers is the preservation of the area’s sensitive environmental balance. For example, this section of the Caspian Sea is home to a rare species of seal and is a breeding ground for the beluga sturgeon, a source of high-quality caviar. Maintaining the ecological balance of the Caspian also has major implications for the people who live and work in the area.
A challenging task
According to Agip KCO, the remote location of the oil field and its often harsh weather conditions present obstacles, particularly for the crews who will work in the area during the installation and operation of a barge-mounted compression station offshore.
The oil field lies in waters between two and ten metres deep, with strong currents and often turbulent waves. Temperatures can rise as high as 40° C (104° F) in summer and fall below -38° C (-63° F) in the winter. Between November and April, the field can be covered by a coat of shifting ice, further complicating the development efforts.
Adding to the difficulty of exploitation, the wells are located in places which are deep and often difficult to reach, and pressure levels of up to 800 bar (11,603 psi) are involved in the recovery of the oil and associated gases. Furthermore, the oil reservoirs contain a large quantity of associated gas whose composition includes the highest quantity ever found of hydrogen sulphide (H2S), an extremely toxic substance which cannot be dispersed into the atmosphere. When recovering crude oil from the field, the associated sour gas will be re-injected into the reservoirs at very high pressure.
HVAC system design
Because of the abovementioned conditions, SBM needed a well-known HVAC specialist in the field. Heinen & Hopman was invited into the project by Lamprell to re-evaluate the basic engineering and ultimately come up with a fixed design.
- Safety (Zone-1 operation, pressurised rooms, blast resistance and H2S filtering).
- Reliable and easy use.
- Easy maintenance due to unmanned operation.
- A 40-year lifespan. 5. GOSH
Together with Lamprell, Heinen & Hopman fulfilled the above brief with a 100% reliable, safe and durable HVAC system serving the compressor hall, instrument room, switchboard rooms, battery room, transformer room and low voltage electrical room.
Special areas of attention related to HVAC
Heinen & Hopman was requested to give special attention to electrical rooms in relation to H2S filtering. The goal was to make sure that no H2S or other toxic sour gas mixtures can enter these spaces, ensuring the safety of maintenance crews and extending the lifespan of the equipment.
Heinen & Hopman was also asked to focus on the electrical rooms related to blast-proof 2-bar static. All main intakes and outlets were executed with SS316L blast-proof dampers. Special attention was also given to any components that might fly around during an explosion/blast. Items such as ducting, air handling units, condensing units and filter units required special engineered supports and framework to ensure that components would not spread all over a barge in case of an explosion. The main consideration was that, while deformation and damage could be allowed to occur, equipment had to stay in its mounted position.
All components were to be suitable for Zone-1 classification and have been certified as such. All materials have been selected for this harsh environment or have been protected to guarantee the same by means of special coating methods.
All electrical rooms are pressurised at a minimum positive pressure of +50 Pa with respect to the outside atmosphere so as to ensure that no contaminated outside air can enter. Sufficient redundancy is foreseen for all essential HVAC systems, cooling, heating, mechanical ventilation, filtering, control, etc. Normal ventilation ducting would not have fitted in the compressor hall if common practice design criteria for ducting had been used. This is why Heinen & Hopman proposed, delivered and installed a directional flow ventilation system, which allowed for considerably smaller dimensions of the ducting system. This was needed to ensure that cooling air would also reach dead spots inside the compressor hall so that no uncontrolled heat loads would occur.
MV serving the compressor hall including dirivent system (all zone-1 Eexd-IIB-T3)
- 3x50% AHU 41,000 m³/h each, incl. 232 kW electrical heating each.
- 2x50% dirivent high-pressure fans 12,300 m²/h each
- Fire & gas dampers, pneumatic type
- Mist eliminators - weather louvers
- 6x axial flow fans (3x 6,140 m²/h each & 3x 44,051 m³/h)
HVAC system LER Local Equipment Rooms (all zone-1 Eexd-IIB-T3)
- 2x100% air cooled 160 kW AC system R134a (ATEX approved by KEMA Netherlands)
- 1x100% air cooled 6.2 kW emergency shutdown AC system per barge R134a
- 2x100% H2S filtering fresh air LER -2x100% exhaust unit serving battery room
- Blast dampers for all main inlets & outlets (2-bar static )
- Fire & gas dampers, pneumatic type
- Mist eliminators
- Weather louvers
All the above mentioned was delivered and installed with a PLC-controlled monitoring system including redundant PLC, and the instrumentation and controls suitable for this particularly harsh environment. All three systems were successfully started up and handed over in December 2012 at D-Island in the Caspian Sea.
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- H&H Headquarters
- IMO No.
- Name Vessel
- Kashagan Flash Gas Compression Barges 3, 4 & 16
- Single Buoy Moorings
- Delivery year
- Country of Delivery
- Vessel type
- Flash Gas Compressor Barges
- 95.0 m