6 replies to this topic

[GaetanDugas420]

Is there a maximum pressure for saturated steam for use in a heat exchanger?

 

I want to heat a stream to 280 deg C, and saturated steam at 305 deg C is around 1300 psig. Is this pressure too high? Should superheated steam be used at this temperature and lower pressure?

 

If so, would it require using a different overall heat transfer coefficient?

[Bobby Strain]

One might consider a fired heater. You withhold much information so it's difficult to advise. You should not count on using superheat in the steam source, however. Are you a student, perhaps?

 

Bobby

[srfish]

Use a lower operating pressure than 1300 psig because that gives an expensive design pressure. What that operating pressure can be is to be determined by economics. The overall heat transfer will vary with the amount of desuperheating..

[GaetanDugas420]

Thanks for the info folks,,

 

 

I need to heat a stream of nylon salt at a significant mass flow rate (18813 kg/hr) from 25 to 280 deg C. I'm not sure about the viscosity of it or the heat duty is 2.4*(10^6) Btu/hr. To heat that stream, I'll need saturated steam at a 1330 psig which from srfish comments it seems like would make it significantly more expensive. Should I use a fired heater or a different heat exchange method, like Dowtherm A?

 

This is for a senior design project.

[breizh]

Hi,

Some info about thermal fluid :

 

https://durathermflu...CFQXHtAodFwoAeg

 

 

Did you check patents ?

The one underneath mentions Dowtherm to heat the stream ..

 

http://www.google.co...tents/US4442260

 

Breizh

Edited by breizh, 05 March 2017 - 12:14 AM.

[gegio1960]

my 2 cents...

- you should evaluate the whole process. for instance: in a Cude Distillation Unit (CDU), the crude temperature is increased from ambient to about 400°C, as the nylon salt in your problem. in the CDU only the last 100-150°C are covered by a fired heater. the remainder of the duty is given by heat recovered from other streams (ie products) in the plant that, in turn, need to be cooled down.

- you should think about the economics of the process. for instance: if you use steam, you've to generate it, to recover the condensate, to prepare the BFW, to provide the fresh water, the chemicals and the fuel, to dispose the boiler blowdown and the flue gases....

.....

good luck! 

[ankur2061]

Thanks for the info folks,,

 

 

I need to heat a stream of nylon salt at a significant mass flow rate (18813 kg/hr) from 25 to 280 deg C. I'm not sure about the viscosity of it or the heat duty is 2.4*(10^6) Btu/hr. To heat that stream, I'll need saturated steam at a 1330 psig which from srfish comments it seems like would make it significantly more expensive. Should I use a fired heater or a different heat exchange method, like Dowtherm A?

 

This is for a senior design project.

Yes, synthetic heat transfer fluids (HTF) such as Dowtherm A are normally used in the polymer (nylon / polyester) industry for heating. Both liquid and vapor phase media can be used depending on the design of the equipment. There are pros and cons for using liquid and vapor media. Have a look at the link below for further insight into synthetic HTF.

 

https://www.cheresou...-oxide-systems/

 

Regards,

Ankur.