Build robust kinetic model even from scratch

It’s all in kinetics

Build robust kinetic model even from scratch – that works

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Build robust kinetic model even from scratch – that works

A reliable kinetic model is the most important or critical component of a successful reactor model. The reactor model is a seamless integration of hydrodynamics, fluid-solid interactions and heat and mass transfer phenomena of each reactor type and operating mode with kinetic model.

The kinetic model (or reaction mechanism and kinetics) consists of three distinct parts: 1) process mechanism or reaction chemistry, 2) process/ reaction rate expressions, 3) the rate parameters. A robust reactor model is the key to prompt and successful scale-up, and safe operation and control of a commercial reactor.

It is needed to seek ● the optimum design and operating window for a chosen reactor ● the best reactor alternative ● the best operating mode like recycle, quench, temperature programming and multi-staging.

It is also needed ● for safe start-up and emergency shut-down ● to minimize (if not eliminate) many pilot and/or demo campaigns ● to minimize pre-mature project failures ● for operation beyond narrow design and operating ranges of original designs to adapt to new feed-stock or new product/ product distribution ● for better/ easier servicing, Debottlenecking and revamp.

Definition and 14-steps details of ‘how-to’ build a robust reactor model are provided in a
CEP cover-page publication authored by a member of Difrex team.
The Difrex models are built to also have the following key properties:
-Mobility (standalone packages) and cloud-based with utmost security against any and all leakages

-Procedures, theories and/or correlations used are validated over decades of testing and validations in reactors of virtually every kind and at all scales from bench to commercial

-Mechanisms and kinetics are based on inputs and outputs that are easily verifiable (such as detectable reactant and product species and measurable hydrodynamic and flow characteristics)

-Minimum adjustable or hypothetical parameters

-Reduced, but adequate, kinetics and mechanism for minimum execution times (mostly in seconds) – to allow real-time applications in plant-wide, easy and remote operation and control

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Move from Hypergolic reactions (spontaneous) of gel/ liquid propellants in a rocket engine to coal combustion/ gasification (fast) in a circulating fluid bed reactor to catalytic reactions (moderate to fast) in a tubular reactor to Hydrocracking of heavy oil (moderate) in a slurry reactor.

Process rate/ kinetics moves from purely mixing rate to predominantly heat transfer rate to chemical reaction rate influenced by mass/ heat transfer rate to chemical reaction rate influenced by gas-liquid mass transfer rate.

Rate of mixing or mass transfer or heat transfer would therefore replace the chemical (intrinsic) reaction rate or influences it depending on the situation. A robust reactor model accounts for such differences.

Primary focus of development work therefore also needs to be shifted from developing the right catalyst to the designs for the best fluid-solid contacting device to the most effective heat or mass transfer system to the best mixer and/or spray nozzle design depending on the case. Any effort to develop a sophisticated chemical kinetic model should be trimmed if other (physical) phenomena control the process rate.

Broad-based, balanced and extensive experience of Difrex that also includes process engineering and modeling and both hands-on and field experiences in all aspects of reactors should serve diverse needs of clients in their labs, production plants and process reactors

Building a reliable kinetic model is a difficult and time-consuming task.
Difrex makes it easy even with minimum information in hand.

We built reaction models as complex as in coal combustion, gas ification and pyrolysis, hypergolic reactions of gel propellants in rocket engines and hydro-cracking/ hydro-treating of heavy oils to as simple as ammonia and methnaol synthes is

Caution

Model is a mathematical representation of data and therefore can only be as good as data.
Perils of both inadequate and ‘big’ data must be avoided.
Inadequate data (for example in coverage of ranges of key variables) leads to a) designs locked in narrow ranges of operation, b) unsafe designs and/or c) less-than-optimal designs.
Big data, on the other hand, may cause skewing or be clouding by sheer volumes of wrong data points leading to wrong rate parameters, or wasted efforts in handling/processing the large volume, for example....
Data filtering, trend analysis and/or regression is of paramount importance during the data collection process to minimize wasted efforts – not after it. See why......
Difrex provides proven and standardized methods of data collection, test unit design and reduced test matrix (reduced number of needed tests) to minimize wasted efforts.

Our expertise in reaction kinetics extends beyond the area of conventional catalytic processes for bulk chemicals production to coal pyrolysis-gasification-combustion to hypergolic reactions of gel-gel propellants in rocket engines.