2 replies to this topic

[rowanlim]

Hi we have a steam-assisted flare using MP steam (min 19 barg, 275°C). The piping is approximately 1.7 km long and this line normally has no flow (NNF). We're concerned about continuous condensate formation hence continuous loss of steam during normal operation. In addition, the flare vendor wants to know condensate inventory that can be expected when flaring operation commences. 

 

I have seen condensate calculation which is based on heat loss via conduction etc, and based on continuous flow of steam (albeit at turndown conditions), but I can't seem to find references for condensate formed in NNF lines.

 

Appreciate any guidance/feedback

[breizh]

http://www.tlv.com/g...g-start-up.html

 

You may find pointers using this resource .

 

Hope this helps

Breizh

[ankur2061]

rowanlim,

 

In a blocked flow or NNF line, the maximum condensate that can accumulate is the volume of the pipe. Unless the condensate is removed / drained that will be the absolute quantity.

 

However, since condensate accumulation in a stagnant line is not desirable. Accumulated stagnant water can cause corrosion in carbon steel pipes. When a NNF steam line is required to be taken in service, accumulated condensate can cause damaging water hammer effects. Thus, traps are invariably provided at regular pipe length intervals and low points in any steam line. Most of these are standard themodynamic traps of 3/4" or 1/2". Most trap manufacturers like Spirax Sarco / Armstrong provide charts for their standard condensate traps which give the flow rate as a function of differential pressure across the trap. A maximum condensate removal can thus be considered as the flow rate captured from the manufacturer's chart multiplied by the number of traps considering that these are standard 3/4" or 1/2" traps.

 

Hope this helps.

 

Regards,

Ankur.