Some years later, environment technology will be improved to the extent that environment
technology can be the same level as thermal efficiency and reliability those are the conventional theme and it will live with the global regulation.
Today's theme is that which engine, slow speed, medium speed and high speed, will be able to stand with environment problem in future and be more advantageous than other engines. That is which can get the leader's position in the environment field.
As the comparison result at this moment, high speed engines will be advantageous because they have so much experience in the environment technology due to severer regulations for in-land use diesel generator plant. But slow speed engines also provide enough potential and the same level as the high speed engines in this technology.
Further research and development work in the environment technology on slow speed engines will recover the disadvantage against high speed engines.
But the most concerned matter is who will pay costs of both such an R&D and hard/soft application when environment technology were applied on board ships. How to absorb the cost should be investigated more significantly by the parties concerned.
When the solution of these expenses were coming late, the application of environment technology would be delayed. Then cooperation and organization of the concerned with the concrete measure are important matter.
This paper is going to disclose our technical aspect on the environment technology; that is how to be able to deal at present and how to deal in future as one theme of this conference. As for 002 emission, it is received commonly that slow speed engine is advantageous due to it's high thermal efficiency. And as for SOx emission, the position of slow speed engine is the same as those of medium and high speed engines because it depends on the sulpher contents in the fuel.
This paper is going to discuss mainly on only NOx emission which conceives competition.
Fig.1-1 shows the tree of our environment technology at this moment. The advantageous technologies in this figure are water injection in the cylinder, inlet air cooling, combustion control and exhaust gas emission control. In view of the engine performance and reliability, water injection and inlet air cooling will be more favorable for us, engine builders. This technological aspect will be explained as follows.
2. NOx EMISSION CONTROL BY COMBUSTION CONTROL.
As for NOx emission aspect, there are basically no difference between slow, medium and high speed engines. That is they all have diesel cycle with air compression and combustion process in high temperature and high pressure condition.
NOx is basically classified fuel NOx and thermal NOx. Fuel NOx depends on the nitrogen contents in the fuel oil, and so the less the nitrogen contents is, the less fuel NOx emission is.On the other hand, thermal NOx depends on not the fuel oil but combustion condition as mentioned below. And so, it is important for us to control thermal NOx emission.
