The Problem
The Esso Highlands project requires that all industrial waste generated during the construction and production phases (as well as putrescible waste from the accommodation camp) is incinerated. That’s so that it doesn’t go to landfill.
KMH Environmental, an NSW-based environmental company, supplied the incinerator to the PNG site. KMH’s preference was for a ‘one stop’ supplier of the whole pollution control system.
Solution
Because of Luehr Filter’s reputation as a leader in incinerator gas cleaning systems, we were selected to provide a dry scrubbing pollution control system. Essentially, we clean the pollutants that come about as a result of the incineration of the operation’s waste.
So as to be able to meet world-class environmental standards for particulate and acid gases – Luehr had to ensure that all gas that exited from the incinerators flue was suitably treated. The system integrates Luehr’s distinctive technologies for absorption reactors, utilisation of the absorbent and the baghouse style filters with reverse pulse bag cleaning.
After an air quench stage, where the flue gas temperature is reduced to a level suitable for absorption of the polluting gases, hydrated lime absorbent is combined with the flue gas upstream of the absorption reactor. The lime is added from bulk bags and injected pneumatically into the gas stream.
The Luehr absorption reactor provides sufficient residence time for the first stage of the absorption process. Coarse and agglomerated particles are crushed or degenerated when passing through a drum partly occupied by grinding spheres, until the size is adequately broken down for the fines to be transported by the gas stream into the dust collector.
The bag house filter collects the fly ash and finalises the gas absorption in the filter cake on the bags. The filter is cleaned sequentially with pulses of compressed air reversing the gas flow through the bags. The main portion of the removed dust cake – ash and partly reacted absorbent – is recirculated by screw conveyors to the inlet of the absorption reactor, where the absorbent is reactivated in the milling drum.
To make sure that the absorbent capacity is fully exploited, at least 20 recirculation cycles are conducted. Because a sizeable amount of absorbent is held in circulation, a surplus is always accessible to accommodate for peaks in the stream of pollutants.
This system of recirculating and discharging the reacted absorbent by mechanical means, combined with minimised heat losses through thermal insulation and trace heating, ensures consistent operation of the solids handling plant. Supplied to site partially assembled, the dust-collectors are installed with horizontally mounted flat bags. The manageable size of these dust collectors has many benefits – they are easy to transport to remote sites and they reduce the plant’s overall size. A fan downstream of the bag filter provides controlled flow for the incinerator and the gas treatment system and discharges the gas to the stack. Amassed incinerator fly ash and expended absorbent is discharged from the bag filter hopper.
Result
Now, in the remote highlands of Papua New Guinea (PNG), a world-class liquefied natural gas (LNG) project is almost finished. It currently has more than 19,000 people working across the project.