DEKRA Industrial
Reaction Calorimetry
Do you understand the thermochemistry and kinetics of your reactions? Many companies don’t and some have suffered
major incidents as a result of scale-up or process modification without a basic appreciation of the reaction thermochemistry.
The way to reduce this potential risk is to use Reaction Calorimetry as a fundamental tool in the understanding of safe
chemical manufacture.
What is Reaction Calorimetry?
It is the measurement of the energy released (or absorbed) from
a reaction when a chemical (or physical) transformation takes
place and it is usually performed in an automated reactor equipped with probes for temperature measurement and electrical calibration. The technique involves comparison of an electrical simulation of an exothermic process with the chemical process
itself and gives an accurate measurement of the heat flow profile
with time.
Why Perform Reaction Calorimetry?
In order to assure the safety of a large scale process by understanding the thermochemistry of the reactions you are performing. Reaction calorimetry provides data on a comprehensive
range of parameters necessary for process safety.
These are: > The heat of reaction and the adiabatic temperature rise of
the process.
> The heat capacity of the reaction mixture.
> The kinetics of the reaction.
> The rate and quantity of gas generation during the process.
> The stir-out time to achieve reaction completion.
> A viscosity profile of the process. An excellent example of how
Reaction Calorimetry can help in defining safe operating
conditions is where a process is susceptible to accumulation
of unreacted chemicals during processing.
This is potentially a very hazardous condition to encounter and
unfortunately provides ideal conditions for loss of control and
reaction runaway. Reaction calorimetry provides the tools to
measure the rate of heat flow as a function of reagent addition
rate and hence determine whether the kinetics of a reaction are
rapid, for example feed rate controlled in a semi-batch reaction
or whether appreciable reactant accumulation occurs, resulting
in increased risk of reaction runaway.
When Should Reaction Calorimetry be
Performed?
As soon as possible, once process conditions have been fixed.
Of course all chemical reaction steps should be assessed for
exothermic reaction potential prior to significant scale-up
but for some processes, for example simple acid / base neutralisations, in-depth study may not be necessary. The exact processes identified for experimental study using Reaction Calorimetry should come from an effective chemical hazard assessment.
This will provide a focussed experimental program, the data
from which should be available before Kilo scale trials are undertaken. Don’t lose sight of the fact that earlier studies may be
necessary when known hazardous reactions, for example nitrations, are part of the process.
The Global Experts
in Explosion & Process Safety
What Can You Do With the Data?
Lots! The data generated by reaction calorimetry is not only
relevant to process safety. It also provides invaluable process
design and optimisation information.
The raw data can be used to: -
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> Determine the kinetics, thermodynamics and gas evolution
characteristics of the desired reaction.
> Identify whether a reaction should be performed by a
batch or semi-batch method.
> Identify whether reactant accumulation occurs – and to
measure the extent and potential hazard associated with this.
> Optimise process conditions & reduce the cost of production.
> Evaluate the consequences of specific process deviations.
> When conducting safety studies, we are often examining
existing ‘safe’ processes and discovering features unknown to
the operator. The data is needed for an effective assessment of
safety facilities & response strategies.
> Increased confidence in your basis of safety.
Chilworth Technology Ltd,
Beta House, Southampton Science Park,
Southampton. SO16 7NS. UK.
Telephone +44(0) 23 8076 0722
Telefax +44 (0) 89076 7866
[email protected]
www.chilworth.co.uk
Reaction Calorimetry at Chilworth What Do We Use & What Do You Get?
At Chilworth Technology our laboratories use the Mettler
Toledo RC1 Reaction Calorimeter. This unit is acknowledged
around the world as the market leader in terms of accuracy,
sensitivity and versatility. An extensive range of conditions
can be examined with reaction studies from -40°C up to
230°C and from full vacuum up to 10 barg. Peripheral equipment can be readily integrated to provide data on gas generation rate, off-gas analysis using mass spectrometry, particle size,
composition (FT IR, Raman spectroscopy), viscosity, etc.
In our service to clients, we provide more than just raw data.
You receive a comprehensive report with detailed data interpretation and recommendations made by Process Safety Specialists. We also offer a customer support and follow-up service that is second to none. We have experence in using
reaction calorimetry to analyse most, if not all, hazardous chemical processes, including polymerisation, nitration, sulphonation, oxidation, hydrogenation, etc.