[How To] Evaluate Reaction Calorimetry [RC1e] study

Hii .....!! Good day to all my visitors.....!!!

Recently i've received some queries asking about addition time of key reagents and some queries related to Reaction calorimetry studies.

And to all, i can say there lies a calculation for addition time, which is based on the evaluation of RC1e data.

But before entering into the calculation, all those who are reading should enter my trans, so that it will become some what easy for me, or else there shall be lot of evolving queries.

Lets start with some below,

What is a key reagent ?

A key reagent is some solution or a compound that involves itself in reaction giving out desired product, without its presence the reaction is incomplete. Key reagents doesn't includes catalyst's.

What does RC abbreviate ?

RC Stands for Reaction calorimetry.

What can we get from RC study ?

RC study gives the reaction rate, heat of reaction, adiabatic temperature rise during addition/reaction, Nature of reaction, Maximum Heat flow.

What does Adiabatic Temperature raise refers to ?

Adiabatic temperature rise refers to the raise in temperature during a chemical reaction where energy is liberated and the liberated energy can't be exchanged with environment / any source.





Lets begin the show,

Usually RC1e data shall be generated form an Isoperibolic(System where the external temperature shall be maintained same) system, Have a look at the isoperibolic system,

There will be sensors to display the temperature raise during dosing of reagents & volume measurement chambers to measure the gas evolution rates.

Now i'll go down the calculation part and how to correlate the data to plant mapping and to be pro-active.

Let's suppose there is a reaction between two reagents( A is KSM & B is a KRM), Methanol be the reaction medium, and C be the catalyst.

Dead Basic reaction

And here as per the process, we need to charge Methanol followed by A, then C followed by addition of B(the beast).
The same process shall be executed in the RC1e chamber and 
1. While dosing the beast B the temperature raise shall be recorded(It will be adiabatic temperature raise T), and 
2. The energy liberated shall also be evaluated(Heat of reaction Hr),
3. After completion of addition the energy liberated shall be evaluated, so that the accumulated energy/percentage of accumulation shall be evaluated. 

Recommended Articles:

[How to] Select a pump, Motor & Line sizings? 

[How to] Calculate volume occupied by a Torispherical Dish ?  

Based on the data generated, we can calculate the MTSR,

Now you guys may get a doubt, that what is MTSR ?

MTSR means Maximum temperature attainable by the synthesis reaction, it exactly means that in a worst case it is the maximum temperature that a reaction can make up.

MTSR = (Operating temp.) + (Adiabatic temp. raise x % Accumulation).

This MTSR should be less than our reaction mass decomposition temperature, 

Now again you may get a doubt, what is this reaction mass decomposition temperature and where the hell can we get it....!!! 
So for those, we can get it from DSC study(Differential Scanning Calorimetry),

I'll explain you about DSC study in detail in my next post.





Coming to our case study,

Let the energy liberated during dosing the beast B be 1000 Kj /Kg of KSM.
% accumulation be 30%, and the adiabatic temperature raise be 49 C.

So now MTSR will be : 50 + (49 x 0.3) = 64.7 ⁰C

Here 50⁰C is our reaction temperature.

So, now we need to evaluate the total energy liberation and need to correlate to plant scale.

So total heat liberated as per RC1e study is 1000 Kj/Kg.

Lets suppose the batch size is 150 Kgs,

So total energy liberated for the subject batch size is 150 x 1000 = 150000 Kj.

And now we need to evaluate whether the addition is feasible in plant scale or not, 
And if its feasible, how much time will it take in the available manufacturing equipment.





Usually there will be some additions which will hold a case where the addition need to be done in some specified time, 
If that's the case then we need to calculate the total time and then based on trial and error we need to select the utility which shall be used for carrying out the operation,

Also Read:

[How to] Calculate Distillation time in a Batch Reactor? 

[How to] Design a Chiller Plant ?  

As per the available lab study, the addition /dosing of beast B need to be done in 2 hours,
And now we need to check the feasibility of the reaction w.r.t. time,

Lets say the reactor is having RT as utility in jacket,

then we need to stick to the basic equation, i.e.,  M x Cp x dT = U x A x LMTD.

and time of addition shall be calculated based on the below formula,

t = ( M x Cp x dT ) / ( U x A x LMTD ).





M is the reaction mass volume at the final stage of addition / dosing,
Cp is the specific heat of the reaction mass - we can get it from RC1e report,
dT is the temperature difference available to perform the operation,
U is the overall heat transfer coefficient,
A is the available heat transfer area,
LMTD is calculated based on the utility and the reaction mass temperatures.

Below is the calculation with RT as utility in jacket,

Heat liberation per Kg of KSM	1290	Kj / Kg
Batch Size	150	Kgs
Total heat liberation per batch	193500	Kj
TR required per 150 Kgs batch size	15.31	TR
Overall Heat Transfer Coefficient	100	Kcal/ hr.Sq.m. K
Reactor Capacity	10000	Lts
Reaction mass volume	4500	Lts
Average density of Rxn. mass	0.9	Kg/L
Total Heat transfer area	19.74	m2
Approx Jacket area	8.88	m2
Coolant in	25	0C
Coolant out	30	0C
Rxn. Mass temperature initial	45	0C
Rxn. Mass temperature Final	55	0C
d T1	15	0C
d T2	30	0C
LMTD	21.64	0C
Heat Capacity	19223	Kcal/hr
Total time for beast B addition	2.87	hr

So here the time of addition is 2.87 hours, which is not acceptable, hence we need to evaluate with a different utility with better efficiency,

Lets try with Chilled water with an inlet temp of 12 ⁰C,

Below is the calculation,

Heat liberation per Kg of KSM	1290	Kj / Kg
Batch Size	150	Kgs
Total heat liberation per batch	193500	Kj
TR required per 150 Kgs batch size	15.31	TR
Overall Heat Transfer Coefficient	100	Kcal/ hr.Sq.m. K
Reactor Capacity	10000	Lts
Reaction mass volume	4500	Lts
Average density of Rxn mass	0.9	Kg/L
Total Heat transfer area	19.74	m2
Aprox Jacket area	8.88	m2
Coolent in	12	0C
Coolent out	18	0C
Rxn. Mass temerature initial	45	0C
Rxn. Mass temerature Final	55	0C
d T1	27	0C
d T2	43	0C
LMTD	34.38	0C
Heat Capacity	30541	Kcal/hr
Total time for beast B addition	1.8	hr

So here it the addition time came around 1.80 hours as per calculation but it may vary based on the practical approach.

You May Also Like:

[How to] Determine heat of liberation without RC study? 

[How to] Select vent size for a reactor / pressure vessel ?  

Hence its better to try out with an other utility with extra efficiency,

Lets go with chilled brine having source temperature of -5 ⁰C

Below is the calculation,

Heat liberation per Kg of KSM	1290	Kj / Kg
Batch Size	150	Kgs
Total heat liberation per batch	193500	Kj
TR required per 150 Kgs batch size	15.31	TR
Overall Heat Transfer Coefficient	100	Kcal/ hr.Sq.m. K
Reactor Capacity	10000	Lts
Reaction mass volume	4500	Lts
Average density of Rxn mass	0.9	Kg/L
Total Heat transfer area	19.74	m2
Aprox Jacket area	8.88	m2
Coolent in	-5	0C
Coolent out	0	0C
Rxn. Mass temerature initial	45	0C
Rxn. Mass temerature Final	55	0C
d T1	45	0C
d T2	60	0C
LMTD	52.14	0C
Heat Capacity	46317	Kcal/hr
Total time for beast B addition	1.19	hr

As per the calculation, the addition time came around 1.20 hours, which is comfortable.

Hence based on the trail and error evaluation, it is found that the reaction between A & B can be carried out with chilled brine utility which is at -5 ⁰C.

That's it.......!!

Now let's think back about situation and the sudden surprises that we may face without RC1e data 😂😂😂😂.

Hope now everyone who gone through the post should have got something about evaluating the RC1e data,

If nay queries feel free to comment / message.

Comments are most appreciated.

Related Posts:

[How to] Design a Scrubber ? 

Guidelines for Process Development & Optimization  

[How to] Select a filter for a specific operation ?  

[How to] Calculate NPSH (Net Positive Suction Head) ?

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