Boiler Redundancy

[invent11]

I am in process of oil fire boilers selection for a new boilerhouse. The required rate of heating steam supply for the boilerhouse is 100,000 kg/hr and the system unavailability as specified by owner is 1E-2. I used word availability and not reliability as it is a poised system. Based on above What redundancy i must consider for the system, 100% ; 50% or ....?
What is reliability figures in industry for the steam boilers with the capacity in range 25,000-100,000 kg/hr steam?
Thanks for your input.

 

[GenB]

Owner/System concurrency is required.
If one boiler what would it happen if down for a period of time 1 hr - 1 day - 1 Week?
I would go 100% buck-up
if several Boilers, then if a couple fail, your plant will be still running and at
certain %, add some 30% buc-up and you may be in good shape.

more info is required.

 

[davefitz]

get a reference list of recent clients of the boiler mfr, and obtain from those clients the availability of the units in their first 5 yrs life. Try to factor out the "infant mortality" items to arrive at the root long term availability.

Also, find out if your client needs 99% availability at 100% design capacity, or if they will settle for 99% availabilitty at 66% design rating- this would allow one of 3 units to be out of service yet meet the clients real needs.

Other things can compromise boiler avaialbility besides the boiler proper- oil supply issues, feedwater quality issues, etc. So spend an equal amount of effort ensuring those are addressed.