6 replies to this topic

[Akshay Jeebodhun]

Hello all, 
 

I hope you are fine.

I have been given to design a deaerator.  I have to calculate the amount of steam needed to increase the  temperature to 105 deg C in the pressurized deaerator operating at a pressure of 1.2 bar.

Condensate return water

Temperature = 98 deg C

Assumption: The amount of steam generated to be used in dyeing machines( TEXTILE INDUSTRY) is equal to the amount of condensate return. 

Therefore, Mass flowrate of return condensate = 22,000 kg/hr
 

Makeup water

The water entering the deaerator is at 85 deg C.

Mass flowrate = ??

Boiler feedwater

Temperature = 105 deg C

Mass flowrate = 22,372.9 kg/hr 

Boiler is operating at a pressure of 5 bar and producing saturated steam at a flowrate of 22,000 kg/hr
 

Flash Steam

Mass flowrate = 34.6 kg/hr

Edited by Akshay Jeebodhun, 08 March 2014 - 06:33 AM.

[Said Salim]

Hi Akshay.

Can you please illustrate your problem by a sketch.

[Akshay Jeebodhun]

Hi Akshay.

Can you please illustrate your problem by a sketch.

Yes sir. i've edited my post
i've attached the sketch
thnks

[breizh]

AKSHAY,

Let you perform heat and mass balances around your system and probably chemical analysis( like TH or others)  on some or all water streams to get the full picture .

 

first of all start with a simplified PFD and identify all the streams , recirculation ,inlet ,outlet ,data available ....

at the end you need to perform the reconciliation of all the data , a tool like solver can be helpful.

 

Hope this helps

 

Breizh

[Akshay Jeebodhun]

AKSHAY,

Let you perform heat and mass balances around your system and probably chemical analysis( like TH or others)  on some or all water streams to get the full picture .

 

first of all start with a simplified PFD and identify all the streams , recirculation ,inlet ,outlet ,data available ....

at the end you need to perform the reconciliation of all the data , a tool like solver can be helpful.

 

Hope this helps

 

Breizh

Mr Breizh
i am provided with only the steam consumption which is 22 ton/ hr ( saturated steam @ 5 bar)
Furthermore, i also know the condensate return which is 22 ton/hr(close circuit) @ 98 deg C.

I've done a mass and energy balance on deaerator as follows : -
Mass balance :     S + MW + C + FS = FW
                            S + MW + 22,000 + 34.6  = 22,372.9             ----------eq 1

Energy Balance : S.(h1) + MW(h2) + C(h3) + FS(h4) = FW(h5)
                
Where h1 = enthalpy of saturated steam @ 5 bar = 2749 kJ/kg
          h2 = enthalpy of  Make-up water @ 85 deg C = 355.9
          h3 = enthalpy of condensate @ 98 deg C = 409 kJ/kg
         h4 = enthalpy of Flash steam @ 1.2 bar = 2680.4 KJ/kg
 


 

Edited by Akshay Jeebodhun, 08 March 2014 - 06:38 AM.

[breizh]

Seems OK ,

Just don't forget to mention the reference for enthalpy ( 0C and liquid state) I guess and for water you need also to add the pressure for your stream  ( 105 C , 1.4 bar as an example).

Hope this helps you out.

Breizh

[xavio]

Akhsay,

 

In reality, there is heat loss to environment from your deaerator vessel.

As breizh pointed out, you should consider P, T in your enthalpy --> h(P,T), because some streams are not in saturated state.

Overall you should get close enough result.

 

Good luck.

 

xavio