Calorimetry

TAMI (IMI) Calorimetry Laboratory

TAMI has extensive experience in reaction calorimetry and the safe scaling of chemical processes. The laboratory includes reactors of different volumes (0.5L-2L) and different materials of construction (glass and stainless steel) capable of working at different pressures, from vacuum up to 60 bar, and in temperatures ranging from -10oC up to 250oC.

Our glass 0.5L reactor is equipped with the Real Time Calorimetry (RTCal) system which allows us to measure the heat of the reaction online during the process.

The thermal parameters measured in the RC1:

• Q - The reaction heat, kJ
• Cp - The heat capacity of the mixture before and after the reaction, kJ/kg·K
• U - Heat transfer coefficient through the RC1 reactor wall, W/m2·K
• Integral conversion at the end of the reaction, %
• ΔH - The enthalpy of the reaction, kJ/mol reactant
• Heat of dilution/crystallization/melting, kJ/mol
• Specific reaction heat, kJ/kg (or liter) reaction mass
• ΔT adiabatic - Possible temperature rise in the case that all the reagents are loaded simultaneously (the reactor is isolated)

After the process analysis, recommendations for safe scale-up will be given according to the reactor size, heat release during the dosing, and cooling capacity. The entire process and data are summarized in a detailed report delivered to our clients.

The reaction will be categorized as a well-controlled reaction or as a dangerous, uncontrollable reaction. In the case of the latter, the TAMI team will provide recommendations on how to better control the heat release (for example, by changing the dosing rate, using controlled dosing, increasing the stirring rate or adding a solvent for better heat absorption).

In the case of extremely dangerous reactions with spontaneous, uncontrolled heat release that cannot be scaled up, our team will study the process and recommend changes to be implemented in the process procedure to allow its safe scale-up in industrial plants.
Apart from thermal properties, the RC1 can also be used to measure the physical properties of undefined solutions.

Some of the measured parameters:

• Melting/Crystallization temperature and heat
• Boiling point
• Heat of dissolution
• Heat of dilution
• Vapor pressure

Reaction calorimetry (RC1)

One of the major challenges in scaling-up laboratory processes in the chemical field is process safety and the ability to predict thermodynamic behavior on a larger scale. Reaction calorimetry helps understand the kinetics of heat release and process and control parameters, and it helps to test the impact of changing these parameters, eventually leading to a safe scale-up of the process and avoiding runaway reactions, loss of control and disastrous consequences.
Reaction calorimetry is based on two key terms -

• Reaction enthalpy ΔHr - (the enthalpy change that occurs when substances are transformed by a chemical reaction. The enthalpy changes produce heat)
• Reaction heat Qr - (related to the overall enthalpy of the reaction, but takes into account the energy release as a function of time)

Generally, chemical processes can be divided into endothermic and exothermic processes. In an endothermic process, the heat flows from the surrounding area into the system, meaning the temperature in the reactor may drop. In exothermic reactions, the heat flows from the system to its surrounding area. In this case, the temperature in the reactor may rise and must be controlled. It is critical to understand the effect of the heat released during the reaction, on the increase in temperature and the risks of a cooling failure.

The main goals of the calorimetry test are to:

• Establish key process parameters
• Determine safety parameters and the criticality of the process
• Determine scale-up parameters such as dosing rates and cooling/heating requirements
• Detect non-scalable processes
• Avoid runaway scenarios and failure conditions

The most common hurdle when scaling up a process from the lab to the pilot scale is the change in the surface/volume ratio. When the volume of the reactor increases, the increase in the surface ratio is lower. Hence, larger reactors have lower cooling capacities. This fact requires special attention and the correct design of the process for safe and practical scale- up.