Abstract
In accordance with the recent tendency using the low grade fuel oil for marine use, the behavior of fire-side fouling has been a more important problem on the marine oil-fired boilers.
There are many problems to be considered for the fire-side fouling especially in using the low grade fuel oil, however the mechanism of the fouling on oil-fired boiler has been well established.
Generally the fire-side deposits are scaled off by water washing which occupies greater part of docking works.
For the purpose of reduction in the formation of fire-side deposits in view point of improving the combustion process due to the microexplosion phenomenon of water-in-oil emulsion, the water injection system was installed experimentally to the existing boiler on the turbine ship “KINKOMARU” which was put in service in 1972.
In this paper, the long-term investigation into the characteristic of fire-side deposits under the emulsified combustion extending over a period of 14 months was evaluated, comparing with the property prior to the installation of water injection system.
The following effects were obtained under the lower excess air combustion due to the emulsified combustion, which seemed to have a good influence for the fire-side fouling.
The water injection rate was maintained at 2% to the fuel oil flow in consideration of watersaving for marine use.
(1) Low level fouling was observed on furnace and superheater
(2) Easy scaling off of deposits on superheater
(3) Reduction in carbon monoxide (CO) concentration was measured.
