A giant carbon dioxide absorber has been transported to the Conoco Phillips gas and oil plant, outside Darwin, in an operation that was almost two years in the planning.

Crowds of onlookers gathered to catch a glimpse of the huge piece of equipment as it was pulled by four prime movers and accompanied by a convoy of police cars.

Together, the absorber and prime movers stretched 85 metres and weighed more than 750 tonnes - making it the largest road haul in the state's history.

Travelling at 40 kilometres per hour, the convoy took almost seven hours to make the 62-kilometre journey from East Arm Wharf to the LNG facility near Wickham point.

The machine, which is used to remove carbon dioxide from incoming natural gas before it is super-cooled and liquefied, will replace an old absorber.

Almost two years of planning went into ensuring the absorber was transported safely and the roads could accommodate the weight and size of the equipment.

The absorber will be connected in September.