konil -
Don't forget, when playing with figures, that the large scale project will benefit from a full 5 years relief from corporation tax. The high capex involved is unlikely to be recovered from profits in a shorter time period, and so the full benefit will be attracted.
It is the "early cash flows" from direct shipping that are likely to suffer from government participation in the profits, not the long term project, which has (a) a 5 year holiday from corporation tax and (b) enough profit to go around anyway!