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Time It Takes To Melt Chdm


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#1 Pingue2008

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Posted 25 May 2014 - 12:13 AM

Dear,

 

 I have been assigned to determine the time it takes to completely melt a given mass of CHDM.

My calculations are attached. I just need a second set of eyes to look at it. The plant produces PET resin. if you have anything in this industry that can help please don't hesitate to share. 

 

Thank you

Attached Files



#2 breizh

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Posted 25 May 2014 - 06:50 AM

Pingue 2008 ,

A few things to consider :

1)You need to add the sensible heat to the heat of fusion , meaning  Hf + Cp *( Tmelting-T room)

 

 

2)For the steam consumption , you only need to consider the latent heat of your steam .

 

3) On operation point of view it's always difficult to melt a product in an Iso tainer equipped with a coil , if I'm not mistaken, an external  loop will help ( Pump) to improve the heat transfer. 

 

Hope this helps

 

Breizh
 


Edited by breizh, 25 May 2014 - 06:51 AM.


#3 Pingue2008

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Posted 25 May 2014 - 08:23 AM

Breizh,

 

Thank you for your response.I added the sensible heat (estimated could not find Cp of CHDM). could you please explain your third comment? Is my sketch illustrate your comment? We are buying an injection system(includes a pair of pumps) that will help inject our melted CHDM in the process. I am not quite sure i understand what you mean by your third comment.

 

Thank you

 

3) On operation point of view it's always difficult to melt a product in an Iso tainer equipped with a coil , if I'm not mistaken, an external  loop will help ( Pump) to improve the heat transfer. 

Attached Files



#4 breizh

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Posted 25 May 2014 - 10:18 AM

Pingue2008 ,

 

 

a) Latent heat of saturated steam at 35PSIA is 939 btu/lb  >>> additional steam is required

 

B) Your sketch is showing my thoughts , having a recirculation loop  with an external pump should  help .

 

Breizh



#5 Pingue2008

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Posted 24 August 2014 - 11:45 AM

All

&

Breizh,

 

I am trying to rekindle this topic because we finally decided to go with CHDM-90. we conducted a lab test and the results were surprising the melting point turned around to be less than 30C and the BP around 94C. I performed calculations to determine how long it will take to thaw the CHDM-90. my problem is that the time comes to be equal for 10#,20# and 30# steam. the flow for the 30# steam seems to be greater i was expecting it to be less (please see attachment). Can someone double check my calculations?

 

Thank you,

Attached Files



#6 breizh

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Posted 24 August 2014 - 06:53 PM

Pingue 2008 ,

 

http://en.wikipedia....exanedimethanol

 

From the link  above it seems that the material is a mixture and its melting point is within the range (106-142 F) . To me it's difficult to assess the Heat transfer coefficient  , it will change over the time .

 

hope this helps.

 

Breizh



#7 Pingue2008

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Posted 24 August 2014 - 07:40 PM

Breizh,

 

Did you look at my cals? are they correct? assuming the heat transfer coefficient I did?

The vendor we are buying the product from spec a 30/70 cis/trans and a melting point of ~41C. like i stated previously we ran the experiment in the lab but have different data MP ~31C and i BP ~94C. now i want to use the data from our lab to determine how much steam i need and the time it will take to thaw the CHDM-90. could you please double check my cals with the assumes. I just i want a different set of eyes looking.

 

Thank you



#8 breizh

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Posted 24 August 2014 - 08:49 PM

Pingue  2008 .

 

The  temperature difference should be ( T steam -T product) .

 

Attached spreadsheets for heating and cooling process vs time

 

Consider the Xcel document attached or refer to Perry's chemical handbook & Process Heat transfer (D. Kern -chapter 18)

 

Hope this helps

 

Breizh


Edited by breizh, 24 August 2014 - 10:22 PM.


#9 Pingue2008

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Posted 25 August 2014 - 11:48 AM

Thank you breizh,

your spreadsheet is very helpful. i still don't understand why my calculations do not match the one using the Kern's formula.

 

Thank you






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