Steam Turbine-Generator Running Without Load

I think there is no problem.Only your steam consumption per unit electricity generated will be high.The turbine will run at an inefficient zone.

Dear Mr. Manzoor

Thanks a lot for your comments and I'm agree with you that kg steam/kWhe will be high. but I'm really worried about fatigue and fast aging will be occurred on rotor and turbine's blades caused by uneven cooling or thermal stress. What do you think Sir?

I assume you're doing this so that you have hot standby generation. You should have no problems as long as you maintain proper steam conditions and a full vacuum in your condenser so that you never have "wet" steam or droplets impinging on your blades.

is there a relationship between loading/unloading process frequency on TG with low-cycle fatigue especially experienced on blades?

Well, the best people to ask would be the turbine manufacturer and the best method to use would be the telephone.

Usually the start/stop process for steam turbines has to be carefully taken care of for, as you said, minimize the thermal stress.

Also you have to account that it takes time to stop/start a turbine and the process requires quite some power that has zero useful work, as in the case you run it unloaded. The difference between them is the stress and the transition (start/stop) process .

What does the manufacturer of the turbine says about the start/stop cycles?

Moreover, in case you unload the turbine,to prevent the thermal stress for start/stop there is the option to run it at a lower rpm while keeping its temperature constant. In this way you reduce the steam consumption at idle.

Dear Mr.manzoor ahmad tarafdar,

Running the Turbine on NO-LOAD for prolonged hours is NOT ADVISABLE. See my Post No.8

DHAYANANDHAN.S

When steam turbines runs generator on No load for so long, the total heat energy from the boiler which is converted to mechanical energy by the turbine is waste and more condensate is accumulated thereby increasing the corrosion of the Turbine blades. You need to disengage the steam and keep the boiler in an idle condition untill its required.....

Mr.Olayiwola,

I do not understand by disengaging the steam and idle condition of boiler.The problem is for a duration of 21 hrs.A boiler & a turbine take much time for start up.Stopping the boiler means stopping the turbine also.The waste of energy will be very high at that case.A turbine must be on slow-roll to keep it available.

Thanks.

Dear friend

You have NOT given the reason WHY YOU ARE RUNNING 2nd TURBINE with out load. If you post the reason, CR4 MEMBERS can suggest correctly.

Minimum Load recommended is 60% and for one turbine 1.5 MW is just 37.5 % Load.

At lesser Load or No-Load, the HEAT DROP per Kg. of STEAM is practically Low and the Last Row blades will run at a higher Temp. which may create problem in course of time.

My advise is DO NOT RUN THE TURBINE ON NO-LOAD 21 Hours. You can stop and re-start and load the turbine.

DHAYANANDHAN.S

If the turbine's exhaust temp.does not increase there is no harm.You mentioned you have to do it in holidays(Once in a week).So if you stop and start the turbine once every week,it is not a recommended practice.

Turbines lubrication system creates a oil film between the shaft(journals) & the bearings on which the shaft floats after achieving certain speed.At low speed the film does not form.At stand-still condition the bearings rest on the journals.When the turbine starts rolling some friction takes place.So frequent start-stop will damage both the bearings & journals.