[How To] Calculate Rate of Distillation in a Batch Reactor


Hello guyzzz..........!!!

Back after many months and sorry for not being regular here, i've received a query from one of the visitor, and i think many of you too have the same question i.e., How to calculate the rate of distillation in a batch reactor....??

And for this query today i gonna put a end mark, i'll explain you with an example here,
but, before that you need to know some basics like, when are we going to do distillation in a batch reactor during a product manufacturing......!!

Most commonly there are 2 cases,

1) after completion of reaction, for impurity removals we will do some workups with solvents like water, which is followed by product layer concentration, simply called as product concentration,

2) The 2nd one will be removal of Moisture from the raw materials, for this the raw materials should be made soluble in a suitable solvent and then the solvent medium is distilled off under vacuum, which will remove the water molecules from the raw materials and make them suitable for carrying out reaction, this is usually done for moisture sensitive products.

So, here now i'll demonstrate an example case study,

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Our case is, we need to calculate the distillation rate in a reactor having a product layer of Ethyl Acetate, and the distillation should be carried out with vacuum NLT 650 mmHg, and temperature NMT 40 deg C,

Let suppose our reactor capacity is 10 KL with MOC SS316, and the product layer volume is around 5 KL say,

Now we need to collect some raw data like HT area of SSR, Specific heat & Density of Solvent, etc.

10 KL SSR will have an HT area of 19.82 Sq.m, but the effective HT area for this operation will be equals to Total HT area x Occupancy of reactor,

Occupancy of reactor = Reaction mass volume / Reactor volume = 5 KL / 10 KL = 0.5,

Effective HT Area = 19.82 x 0.5 = 9.91 Sq.m,

For More info on calculating HT area of reactors, Read this:

[How To] Calculate Reactor HT Area

Density of Ethyl Acetate is 897 Kg/cu.m, Specific heat : 0.454 KCal/Kg. K , Latent Heat of vaporisation is 87.6 KCal/Kg,

As the MOC of the reactor is SS316, the Overall Heat Transfer Coefficient can be considered as 250 KCal/Sq.m. Hr. K.

If you want to calculate the Overall Heat Transfer of a reactor with more accuracy, then read this post,

[How To] Calculate Overall Heat Transfer Coefficient 

So now, getting into our calculation we need to calculate the amount of energy that our HT area is going to transfer per hour, and that we can calculate as follows,

Q = U x A x LMTD,

Sorry guys, i forgot to calculate the LMTD previously, anyway now i'll do it for you,

for calculating the LMTD we need two streams, one is utility stream and the other one is batch volume,

So , coming to Hot water utility, now you may have one doubt that why i've used Hot water as utility, the reason is we have a Specification that reaction mass temperature shouldn't exceed 40 deg C, thats why i've considered Hot water instead of Steam, and now another question may arise in your mind, what can be the hot water set point, usually we will maintain a Delta T of 10 deg C, so the Hot Water Set point will 40 deg C + 10 = 50 deg C.

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so now Th1 = 50 deg C, Th2 = 45 deg C (say), Trxn = 25 deg C [ i've considered the reaction mass temperature as 25 deg C because at 650 mmHg of vacuum, the boiling point of ethyl acetate will be hardly 25deg C, this can be calculated from antonie equation],

LMTD = ( ( Th1 - Trxn ) - ( Th2 - Trxn ) ) / Ln [ ( Th1 - Trxn ) / ( Th2 - Trxn ) ]
            =  ( ( 50 - 25 ) - ( 45 - 25 ) ) / Ln [ ( 50 -25 ) / ( 45 - 25 ) ]
            =  5 / Ln [ 1.25 ] = 22.727 Deg C,

Now, lets resume our calculation,

Q = U x A x LMTD

    =  250 x 9.91 x 22.727 = 56306.143 KCal.

Now we need to know what is the Heat load of the Reaction mass i.e., summation of Sensible heat & Latent heat,

Qhl = Sensible heat + Latent heat

      =  M x Cp x dT   +   M1 x Lambda

      = ( V x Rho )  x Cp x dT   + M1 x Lambda

      =  5 x 897 x 0.454 x ( 30-25)  +  M1 x  87.6

      =  10180.95 + M1 x 87.6

Now, we need to equate the overall heat load to the reactor supply load i.e., 56306.143 Kcal,

10180.95 + M1 x 87.6  =  56306.143

M1 x 87.6  =  46125.192

M1 = 526.54 Kgs of Ethyl Acetate = ( 526.54 / 0.897 ) Lts of ethyl acetate

M1 =  587 Lts of Ethyl Acetate.

If you guys understood the above done calculation clearly, Then say Cheers :)
And if any doubts were there, please ask us, we are happy to help you,

Comments are most appreciated :)

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About The Author

Hi! I am Ajay Kumar Kalva, Currently serving as the CEO of this site, a tech geek by passion, and a chemical process engineer by profession, i'm interested in writing articles regarding technology, hacking and pharma technology.
Follow Me on Twitter AjaySpectator & Computer Innovations

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[HOW TO] Calculate Density of solvent Mixture


Hello Everyone.....!! Back after many days, with a Basic post, this involves only basic which many of the guyz have forgotten after entering Pharma Industries, I don't mean that Pharma Industry is the main reason but i just mean that while involving a high degree of calculations Engineers will prefer to use appropriate figures rather than accurate figures, but we need to keep one thing in mind that whenever we keep enlarging our vision we need to remember the basic things, that's the reason i have taken this topic here.

 Basically while trying to calculate the density one should be aware of what does a density mean exactly and what units does it holds, as well as how to calculate it for a mixture when two or more solvents was involved from individual densities.

What is Density ?

The Basic definition that everyone knows is Mass/Volume, and it will hold the units as Kg/Cu.m in SI units, and gm/cc in CGS units.

How to determine the density of a solvent practically ?

As this site particularly deals with Pharma Industry i've mentioned directly SOLVENT in the query without mentioning as liquid, please don't bother about that. The simple way to determine the density of a solvent in real life is to take some known volume in a bottle or a container and weigh it, calculate the net weight of the solvent in the bottle/container, then divide the weight with the known volume, then the derived figure will be Density, but please take care of the units that you consider, i'm not responsible for any mistake that was done by you by considering wrong units.

How to calculate the density of solvent mixture from individual densities ?

This is somewhat a difficult task for some guyz because there lies 3 equations hitting up our mind while we think to calculate but within those three equations there lies only one correct equations, now i'll give you those three equations below,

Equation 1 :

Density of Binary Mixture = ( Mass fraction of Component 1  *  Density of component 1 ) + ( Mass fraction of component 2 * Density of component 2 ),

Simply, D = ( X1 * D1 ) + ( X2 * D2 ),

Equation 2 :

Density of Binary Mixture = 1 /  ( ( Mass fraction of Component 1  *  Density of component 1 ) + ( Mass fraction of component 2 * Density of component 2 ) ),

Simply, D = 1 /  ( ( X1 * D1 ) + ( X2 * D2 ) ),

Equation 3 :

Density of Binary Mixture = 1 / ( ( Mass Fraction of Component 1 / Density of Component 1) +  (Mass Fraction of component 2 / Density of Component 2 ) ),

Simply, D = 100 / ( ( X1 /D1 ) + ( X2 / D2 )).

And Apart from these three equations some guyzz will do some funny calculations as Mixture Density = ( Component 1 Density + Component 2 Density ) / 2, this is very cheap calculation, so my dear engineers learn the correct way don't do calculation like this one.

Getting into the matter seriously, Out of the three equations those were mentioned above the third one is a perfect one, you may have a doubt that why did i said that as perfect instead of Correct, because based on some special cases the Equations 1 & 2 may be applicable but not to all cases.

So the Above mentioned Equation 3 is perfect one while you want to calculate from Mass fractions, and there is some other way of determining the Mixture density that is based on volume fractions or volume percentage.

i.e., Density of Binary Mixture = ( ( Volume % of solvent 1 * Density of solvent 1) + (Volume % of Solvent 2 * Density of solvent 2 ) ) ,

Simply, D = ( ( ( V1 / V ) * D1) + ( ( V2 / V ) * D2 ) ).

So, i think now you got what is the exact procedure to calculate the Density of a Mixture, if you have any queries please feel free to contact us, 

If you understand what i delivered above, Say Cheer's.

All Valuable Comments are appreciated. Thanks :)

About The Author

Hi! I am Ajay Kumar Kalva, Currently serving as the CEO of this site, a tech geek by passion, and a chemical process engineer by profession, i'm interested in writing articles regarding technology, hacking and pharma technology.
Follow Me on Twitter AjaySpectator & Computer Innovations

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Operational Qualification - OQ

Back After a week......!!

Today i'll explain a little about operational qualification, for that you need to know what does OQ exactly mean...!!

What is Operational Qualification ( OQ )  ?

The Operational Qualification Protocol is a collection of test cases used to verify the proper functioning of a system. The operational qualification test requirements are defined in the Functional Requirements Specification. Operational Qualification is usually performed before the system is released for use.Depending on your needs and the complexity of the system, Operation Qualification can be combined with Installation Qualification or Performance Qualification.Operational Qualifications should be approved before protocol execution. A copy of the unexecuted protocol should be kept in the validation package. The unexecuted protocol should be approved by the System Owner and Quality Assurance. The executed protocol should be signed by the tester and reviewed by the system owner and Quality.

What are the Sequence of steps those needed to be executed for OQ Approval ?

This will be first initiated with 

1) Instrument Calibrations,

2) Leak & Vibration Test,

3) Key Functions,

4) Deviation & Corrective Action Report,

5) Observations and Review of Documents,

6) Conclusion,

7) Approval.

Now, i gonna make you each step very clear,


The instruments identified for calibration during Installation Qualification Protocol, calibrated and the observations and or results to be recorded. Certificates provided by Supplier, In house and external calibration reports to be enclosed as attachment to this Qualification report.
The Guages and all the sensors were tabulated and a calibrated frequency and last calibration date will be mentioned to ensure they all were in proper working condition, which is shown below.


After checking all possible test functions, leak & vibration test will be carried out to demonstrate, that the equipment is installed without any leakages.


The key functions will be classified in the specific headings. Each function test shall be recorded in a separate test data sheet specifying each test function action, expected output/result, actual output/result, and remarks.

To identify the utility services those are connected to the equipment, and to check that the connected utility is giving the rated performance as per the requirement.


After checking all possible test functions, minimum three process simulation cycles will be carried out to demonstrate, that the equipment as an integrated system is capable of achieving the desired results when operated as per the set parameters.

Similar two trials need to be taken for consistency, if found ok then the simulation cycle will be completed, or else 3 successive trails should be taken,


Description of Deviation & Date observed:


Person Responsible for Corrective Action & Date Assigned :


Corrective Action Taken & Date Conducted :



The following prepared document is checked for any loopholes or mistakes that were need to be solved before approval,


This includes the comments of the persons who gonna review and and the approver comments, and their conclusion.


Now Its Time for Document Approval, if everything done perfectly, then it will be approved.

That's it......!!! Its Done now.......!! Cheers.......!!!!

Any queries feel free to contact us..... We are always happie to help :)

About The Author

Hi! I am Ajay Kumar Kalva, Currently serving as the CEO of this site, a tech geek by passion, and a chemical process engineer by profession, i'm interested in writing articles regarding technology, hacking and pharma technology.
Follow Me on Twitter AjaySpectator & Computer Innovations

Read More »