According to Annex V of MARPOL 1973/78 convention of IMO, guidelines regarding the waste material storage and disposal of waste at sea need to be strictly followed. Incineration of various materials such as galley waste, food scraps, accommodation waste, linen, card boards, oil sludge from lubricating oil, fuel oil, bilge and purifier, and sewage sludge, is one of the most effective ways of disposal and saving storage capacity of the tanks and waste storage containments on ships.
Moreover, the residue left from the incineration can be easily disposed off as it mainly consists of ash.
Construction and Working
The image below shows the diagram of a vertical cyclone type incinerator with a rotating arm device to improve combustion and remove ash and non combustibles from the surface.
A sludge burner is placed in the incinerator to burn and dispose sewage, sludge and waste oil. An auxiliary oil burner is also fitted to ignite the refuse. Automatic controls provided for the system secure the igniter when the refuse starts burning without the need of the igniter. Combustion air is supplied with the help of forced draught fan.
A loading door, pneumatically operated, is provided to load the refuse. An interlock is also provided with burner and forced draught fan, which trips when the loading door is in open condition as part of the safety.
Solid waste is fed from the loading door and the incineration process starts after closing the door. Liquid waste is fed into the system when the refractory of the incinerator becomes hot.
After the completion of the incineration process, the incinerator is allowed to cool down and residue like ash and the non combustibles are removed by pulling the ash slide door. The rotating arm scrapes off the entire solid residue in the ash box which can be easily disposed.
During incineration it is important to control the exhaust temperature, which should not be very high or too low. High temperature could lead to melting of metal and can cause damage to the machinery, whereas too low temperature will not be able to burn the residue and sterilize and remove odor from the residue.
This temperature control can be achieved by introducing cold-diluted air in the exhaust stream at the point which is as close to incinerator discharge.