6 replies to this topic

[srktalasila]

Dear all,

We had surplus impure steam ( generated from effluent after evaporation) at 2.2 kg/cm2 g and this cant used anywhere in my process due to impurities. We would like to use this thermal energy in a different route.

We are planning to circulate DM water at shell side and tube side impure steam.So, Phase changes will occur and DM water becomes Pure steam and impure steam becomes as condensate.

 

How to calculate theoretically whether the above changes will occur or not.

 

Plz suggest for the above problem.

 

Regards

Talasila

[breizh]

Hi,

You need to perform balances ( mass and heat) and define the objectives :

recover all the heat available or recover the necessary quantity to bring the DM water to a certain temperature .  

what are the quantities available ( steam and water) ?

 

Starting  with the steam , what is the quantity available ?I guess the steam is saturated meaning that mean the quantity to transfer should be the product mass * latent heat of steam at 3.2 bars absolute .

 

Now based on your DM flow rate , cp of water , Tinlet  , you should be able to calculate the Toulet of the water .

 

Give a try .

 

when you are clear with the mass and heat balances you can start to design the HX

attached to calculator for a predesign .

http://www.engineeri...mal/sizing.html

 

http://www.freecalc.com/heat.htm

 

Good luck.

Breizh 

Edited by breizh, 28 August 2020 - 01:36 AM.

[Chemitofreak]

Just out of curiosity,

 

Where are you going to use this steam produced from DM Water?

 

How much steam is produced in the evaporator?

[srktalasila]

Hi Breizh sir,

Surplus impure steam available qty : 6 tons/hr  and DM water available qty: 10 tons/hr. 

 

Now we are using Plate Heat exchanger to convert impure steam as pure steam with DM water. We have to invest huge money to procure gasket for PHE. That's why im thinking why don't we use shell & tube heat exchanger instead of PHE.

 

Now my doubt is, shall we use shell& tube exchanger instead of Plate heat exchanger or not. How to go ahead theoretically.

 

Regards

Talasila

[breizh]

Hi Talasila ,

a few comments : 

1) Definitely a "bad" idea to use Gasketed plate heat exchanger for your application ! 

2) To get a good support you should give us more information about your process , I'm curious about your current evaporation system . Can you share a PFD ?

3)  Consider the link attached where you can find some info about energy saving  .   

      https://www.energy.g...o/steam-systems

 

4) a few options coming to my mind : Preheat the feed of your evaporation system  , MVR  to recover the steam and supply your evaporation system  ,.....

5)  regarding DM , what is the usage in your plant ?  what is the pressure ? 

 

Hope this is helping you

Breizh

[breizh]

Hi Talasila,

Thanks for the feedback .

To me I will investigate the MVR process and consider if not the case the possibility to use multiple effects evaporators .

If you want to stick to the idea to use HX to recover energy and transfer it to the DM water , it should not be a problem.  Perform an heat balance to evaluate the temperature of the water at the outlet of the HX  . It should be a single phase . 

 

Consider the literature attached to support your work

 

Good luck .

 

Breizh 

[srktalasila]

Hi Breizh sir,

Thanks for prompt reply to give an idea to proceed further.

I will work out MB & EB based on the resources provided by you and revert.

 

 

Regards

Talasila