Condenser

Yes, it will. At reduced thermal efficiency, that is.

i still have doubt, if condensor is not used then what happened to steam after tubine

If turbine does not trip on "low vacuum" . . .will make big cloud in room . . . usually after blow out of condenser over pressure plug.

If you have 100% extraction steam capability then it is possible that you may be able to run without a condenser, however, there is a certain amount of steam has to be "leaked" through the low pressure expansion stages of the turbine in order to keep the blades and exhaust casing cool. If this steam is is not there then windage created by the blades causes unacceptably high temperatures.

This leakage steam will have to go somewhere if the condenser is not working.

if steam is directly released to atmospere after work done over turbine then any effect is there? if efficency drop then how much efficiency drop?

Vimalkumar, Look at the left hand diagram, it represents an extraction steam turbine. If you extract 100% of the steam, then in theory there is no steam going to the exhaust/condenser. However as stated in my previous post, there is a minimum amount of steam must be directed through the next stages in order to keep that area of the turbine cool. This steam would have to be vented if the condenser was not working.

If your turbine is a non-extraction type then 100% of the steam would have to be vented, which would be very ugly.

Your turbine will probably be at its most efficient (from a machine point of view) with the condenser working properly and minimum extraction (if it is an extraction design). The difference you can find out by looking at the steam diagram for your specific machine. Nobody could possibly guess this number.