Special Equipment for Special Purposes including Application Rules for Dispersant

Mini-Trawl	Sweeping

The trawl bags can be connected in line with up to three bags. When the outer bag is filled with oil, it can be detached from the other bags from a small dingy by pulling out a steel wire. Once the outer bag is detached it starts separating from the other bags. Small lines will automatically close the new, outer bag for holding the oil going into the trawl system.

The detached bag is protected by a heavy plastic coating which closes around the trawl bag when towed in the water. This protects the system when taken onshore for cleaning.

RO-CLEAN DESMI produces a specially designed Multi-Purpose Boom Cleaner. It can be used for cleaning Ro-Boom, Troilboom and other types of booms without spring systems. A set of four high pressure nozzles cover the entire width of boom which cleans both sides of the boom wall. The system is mounted in a container for handling the contaminated cleaning water. A pump for removing the contaminated water in the tank is also delivered.

Cleaning Unit in Russia	Cleaning Unit also with Settling Tank

Floating tanks are a RO-CLEAN DESMI speciality, called the Ro-Tank. The floating tanks are produced in sizes from 5 – 50 m³. The material is heavy duty rubber similar to the Ro-Boom Containment Boom. The tanks have a filling connector as well as an air vent system and are fully equipped with filling hoses, towing equipment, buoyancy members, etc. They have been certified by Lloyds for seaworthiness and are found to be excellent.

10 m³ Ro-Tank towed in water	Ro-Tank in operation

Chemical Combat Means

RO-CLEAN DESMI is also supplying systems for Chemical Combat of Oil Spills. The system is designed for vessel operations and comprises a pump unit which can be diesel or electrically driven. Further the system comprises two spray arms with length up to 6 meters. The spray arms are supplied with nozzles giving the optimum spraying of the dispersant used.  

As the dispersant used are divided into three categories:

-          Type 1: Neat, non-concentrated dispersant
-          Type 2: Diluted,  Non-concentrated
-          Type 3: Neat, concentrated

The RO-CLEAN DESMI spray unit is prepared for both neat and diluted dispersant. For the diluted type of dispersant the rate is 1:10.

When using dispersant it is important to be aware that there will always be restrictions for using dispersants. Most European countries do not allow the use of dispersant without specific approval from the authorities. Even with a general permission for using dispersant there are some restrictions with regard to:

-          Exchange of water
-          Water depth
-          Special restrictions due to fish hatcheries
-          Special restrictions due to bird nesting, etc. 

Further is should be noted that it is important to know the type of oil spilled as the development of dispersants makes it possible to use specifically efficient types of dispersants for specific types of oil. 

The application of dispersant depends upon type of dispersant used and of course of the amount of oil per area. 

The type 1 dispersant is used with a dispersant to oil rate: 1:3 – 1:1
The type 2 dispersant is used with a dispersant to oil rate: 1:3 – 1:1 (1:30 – 1: 10 when neat)
The type 3 dispersant us used with a dispersant to oil rate: 1:30 – 1: 10

Application rate = The amount of oil per hectare x dosage (l/ha).

PDR (Pump dosage ratio in litres per minute) = 0.0031 x Application rate (l/ha) x Speed (knots) x Swath (m)

Example:

Average thickness of the oil is 1 mm, equal to 0.001 m. Speed of the vessel is 4 knots. The length of the two spray arms (incl. width of vessel) is 20 meters. 

First the amount of oil per hectare:
10,000 m² x 0.001 = 10 m³ ≈ 10,000 litres
Dosage ratio is estimated to 1:20 (type 3), this is giving the application rate:
10,000 x 1/20 = 500 litres of dispersant per hectare
PDR = 0.0031 x  500 l/ha x 4 knots x 20 m = 124 l/min. 

If the pump has a maximum of e.g. 100 l/min then the speed has to be reduced:
PDR = 0.0031 x 500 l/ha x 3 knots x 20 m = 93 l/min.  

Commissioning and Training in Oil Spill Response

RO-CLEAN DESMI always offers the possibility of commissioning of our equipment. For larger projects the commissioning will be an integrated part of the price. Besides this practical demonstration of our equipment we are also skilled in more theoretical training courses. They can be specially designed for a specific purpose or they can be the IMO level I, II and III courses.