HP steam conveying

[heatcycle]

We are trying to determine whether it is possible to convey HP steam (500 Celcius and 60 bar) for a distance of 400 mt.
I would appreciate if any-body give a tip out of experience or calculation, related to pipe material quality,condensate amount and pressure losses?

 

[DSB123]

heatcycle,
The answer is yes. We have HP steam which is conveyed further htan 400mtrs. The conditions at the other end will depend on the extent of the insulation you apply (i.e. thickness and type), the ambient conditions(heat transfer/loss), the size of the line(pressure drop). The amount of condensate again is dependant upon the physical attributes of the system.

 

[davefitz]

pipe material would be 1.25 Cr-1 Mo or 2.25 Cr - 1Mo ( P11 or P22) for a 500 C design temperature. Just be certain the design temperature truly represents the max temp expected for the steam.

pressure drop allowable is dependent ont he process requirements. For a power producig station, a typical HP main steam line loss at max flow is 2.5% of inlet pressure, including valves, bends, and straight portion. For other processes there is an economic tradeoff between pipig friction loss, pump power at upstream system, and desing pressure of upstream system.


Condensate piping and valves should be designed to handle the cold startup case if the steam is to go to a turbine, so one must calcualte the energy absorbed by the piping during this scenario . For an 60 bar system I would guess the drain valves and piping would be 40 mm nominal.

 

[TD2K]

As others have said, it is quite possible. The pipe would be sized for a velocity likely in the range of 100 to 125 ft/sec (30 to 40 m/sec) depending on what you want to allow for pressure losses. If you want to minimize pressure losses, go to the next larger size. What is your intended flow rate?

For condensate losses, you'll need to do a heat transfer calculation based on your ambient conditions and what amount of insulation and type your specs call for. If this is a fairly large flow, you typically don't lose enough heat to remove all of the superheat from the steam so calculated steam losses for operation are zero. However, on startup you can have significant amounts of condensate as you heat the piping up to operating temperature, the duty being supplied by condensing some of the steam in the system.