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[chau]

Dear all



I certainly have a chief confusion related to circulation ratio.Well just to get sense of topic , iam talking about waste heat recovery system.What I got to understand so far is Boiler with vertical tubes are being treated as a natural circulation, the motive force to drive the fluid(steam mixture in riser tubes and water at downcomer) is density difference hence is known as natural circulation.

Likewise boiler with horizontal tubes or inclined tubes need to have circulating pump to meet the required circulation ratio as the buont force on horizontal tubes may create the stage of DNB(Departure from nucleate boiling) hence damage the tubes , hence known as forced circulation



Now my concern is related to , vendor offering the boiler to us . Apparently there is two boiler

1) AQC Boiler (Natural circulation)

2) PH Boiler (Forced circulation)



The orientation as follows



Boiler Shell (Gas flow) Tube (Water flow)

1) AQC Vertical Horizontal

2) PH Horizontal Vertical upside



Now if I stand on the above stated concept of natural and forced circulation , the param, the orientation of gas and water flow may create some vague for me .



Culprit for vague



PH Boiler as enlightened above will have vertical tubes and hence should be the natural circulation , whereas our supplier has included the circulating pump on this boiler hence will be treated as forced circulation. Subsequently the AQC boiler as per concept should have the pump due to horizontal tubes , but the our supplier has avoided the use of pump in same which force me to conceive it as a natural circulation.



Kindly have me your opinion