CASE STUDY 

Marine Boiler | Oil to Gas Conversion

 

PLANT LOCATION West Coast of Africa
FACILITY DESCRIPTION VLCC Oil Tanker converted to FPSO
BOILER TYPE     Bi Drum
BOILER CAPACITY 80 [Tonnes/hour]
STEAM CONDITIONS HP: 65 [Bar] @ 510 [°C]

 

Conditions:

One of the most significant developments in the oil and gas industry in the seventies and eighties was the coming of age of the super oil tanker. With a statutory practical operating life limited to 25 years, many of these tankers were ultimately retired from service and utilized as Floating Production Storage & Offloading [FPSO] facilities on offshore well heads. To allow these tankers to be redeployed for FPSO operation, their main boilers had to be converted from heavy fuel oil firing to natural gas.

Converting a boiler originally designed to fire oil to gas firing has a profound impact on the internal heat recovery within the boiler and can adversely impact:

  • The maximum output that the boiler can safely achieve,
  • The superheater metal temperatures; and
  • The effectiveness of the steam attemperation system.

It is for this reason that marine certifying authorities normally require a gas firing study be undertaken as part of the FPSO conversion certification process. This study involves modelling the performance of the boiler to identify any boiler modifications that may be required to facilitate its conversion to gas firing, and determine whether or not the output of the boiler will need to be limited on gas firing.

Design Boiler is a leading international service provider of FPSO boiler conversion designs and has completed studies on many FPSOs that are currently in service around the world. We have also been involved in reassessing a number of FPSO conversions that have not been properly designed or implemented. In those cases, Design Boiler was able to properly characterize the shortcomings and provide cost effective strategies to remedy them.

Purpose developed computational resources and long-standing experience in the marine, oil, gas and industrial boiler market has enabled us to redesign boiler components and critical systems so they may operate safely under revised gas firing conditions and comply with the demanding requirements of the certifying authority.

 

FPSO offloading to another tanker at sea
On deck production facility of an FPSO
FPSO Engine room showing converted propulsion boilers