The development of heat flow calorimetry as a tool for process optimization and process safety

Abstract

Classical thermo-analytical micro methods (DTA, DSC) are still very useful for process work, but medium scale instruments based on heat flow measurement are attaining an increasingly important role in this domain.

As in many areas, development of reaction calorimetry for industrial applications was driven by needs and by available means (technical capabilities).

The needs have been fairly constant over the past decades. There are data needs:

• Reaction rates

• Heat release rates

• Heat of desired reactions and decompositions

• Heat capacities and heat transfer capacities

It took the specialists of calorimetry a long time to recognize and to accept the operational needs, namely:

• Working under controlled temperature conditions (constant temperature, temperature ramps)

• Adding components during runs (continuously or in portions)

• Simulation of industrial mixing conditions

The main driving force for the development of process oriented calorimetric instruments was the evolution of electronic hardware which made the control of heat flow on a (non micro) laboratory scale easy.

The paper gives an overview on the principles of heat flow control and reviews the developments of the fifties and sixties, when the matching of heat flow with heat release by reactions was the goal.

With the advent of fast and powerful laptop computers, the focus has shifted. Now, the deduction of true heat release rates from signals which may be badly distorted, is the goal.

Some recent developments are reviewed and the hope is expressed that calorimetric equipment, inexpensive enough to be affordable for every laboratory engaged in process work, will be available soon.