John Thompson was awarded the multi-million rand contract in late-2013 and manufactured and supplied the pressure parts, combustion equipment and other critical components, while the fabrication of non-critical parts and the assembly and erection of the boilers were undertaken by local contractors under John Thompson’s direction.
The contract was the first contract won by John Thompson for industrial watertube boilers in South-East Asia.
The boilers are designed to supply 100 t/h when bagasse-fired and 50 t/h with marine fuel oil .(MFO). They operate on bagasse during the season but on wood chips or oil during the off-crop period to supply steam and electricity to the refinery.
To meet the refinery turn-down operating requirements during the off-crop period, the boilers are capable of steaming at a load of 30 t/h continuously when firing bagasse, wood or MFO, as specified.
As the plant is located in an earthquake zone, the boilers are a top-supported design, suspended from a steel structure by specially designed hanger rods that allow them to swing during an earthquake, greatly reducing any potential impact on the boiler pressure envelope.
The design incorporates a tall water-cooled combustion chamber, two-stage pendant superheater, mud drum attemporator, single-pass generating bank and heat recovery equipment comprising a two-stage parallel-flow air heater and an economiser to meet the required initial thermal efficiency on net calorific value (NCV) of 80.67 %.
The boilers are fitted with John Thompson’s well-proven three-drum bagasse feeders, pneumatic spreaders and stationary water-cooled pin-hole grates. Soot-blowers are provided to keep the boiler heating surfaces clean during extended periods of oil firing and each boiler is equipped with a steam heater to heat the feed-water to prevent dew point corrosion of the economisers.
The draught plant incorporates single forced draught (FD), secondary air (SA) and induced draught (ID) fans for each boiler. The fans are fixed-speed damper-controlled units. Each boiler has an electrostatic precipitator installed between the back-end heat recovery equipment and the ID fan in order to limit particulate emissions to below 50 mg/Nm3.
Flue gases exit through a common self-supporting chimney stack. The fly ash is removed by a sluice system and the coarse ash is discharged into a common submerged-belt ash conveyor.
Media release
About John Thompson:
John Thompson is a division of ACTOM (Pty) Ltd, the largest manufacturer, solution provider, repairer and distributor of electro-mechanical equipment in Africa. ACTOM employs over 7 500 people and has an annual order intake in excess of R7,5 billion.
As the plant is located in an earthquake zone, the boilers are a top-supported design, suspended from a steel structure by specially designed hanger rods that allow them to swing during an earthquake
