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Boiler System

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#1 ChrisHughes


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Posted 06 November 2019 - 01:19 PM



Attached is a simple flow of the system I am working with. 


I have an outlet temperature of 1000 Celsius from a sulfur burner, which is passing through a waste heat boiler. I know I need to raise the stream passing via the shell side to approx. 242 Celsius because we are producing 35 barg steam for export. 


The blue stream is from a deaerator which is pumping water at 99 Celsius.


My question is what temperature would the two temperatures and phases be for the stream entering the shell side of the waste heat boiler, and leaving the shell side of the boiler feedwater preheater and entering the steam drum. 


Is the first one (entering the shell side) water at about 99 Celsius? And is the other one needing to be at the 242 Celsius?




Edit: Or should the 99 Celsius water from the deaerator be entering the steam drum directly? Then the water leaving it is at 99 Celsius and being heated via a waste heat boiler to 242 Celsius?

Attached Files

Edited by ChrisHughes, 06 November 2019 - 01:26 PM.

#2 Pilesar


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Posted 06 November 2019 - 05:43 PM

The steam drum will be at the pressure required to export 35 barg steam. The water in the steam drum will be at saturation temperature or else you cannot have steam and water in equilibrium. Refer to steam tables for that value. This temperature is also that of the feed to the waste heat boiler (WHB). The steam drum is higher elevation than the WHB so the shell side of the WHB will be at a higher pressure due to static head. This means the water entering the shell side of the WHB will be lower than its saturation temperature. As you add heat to this water stream, the temperature will rise but it may not change phase very much inside the WHB. As the hot water rises to the steam drum again, the pressure is reduced and a small portion of the stream boils. The vapor phase separates from the liquid in the steam drum. The deaerated water is make up to the steam drum to replace what vaporizes. As the diagram shows, it is preheated closer to its saturation temperature prior to entering the steam drum. This is to make the best use of the available process heat. The water flow rate from the steam drum through the WHB depends on pressure drop in the hydraulic system as it regulates itself to form a thermosiphon due to the difference in densities between the feed to the WHB and the effluent from the WHB.

#3 PhilippM


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Posted 06 November 2019 - 05:48 PM

I don't think you provided enough information to say what temperature the water leaving the feedwater preheater will have. If I remember correctly a feedwater preheater should be designed to heat the feedwater to the temperature in the steam drum, with as little subcooling as possible.

Edited by PhilippM, 06 November 2019 - 05:49 PM.

#4 breizh


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Posted 07 November 2019 - 02:59 AM



Hi ,

To support your work and others , 

A link to  learn about steam , steam boiler, etc .


Good luck


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