Thermal process engineering
The basis of thermal process engineering is thermal separation processes. In mixtures made up of at least two components, heat and material transfer processes are used to selectively change the composition (concentration) of the mixture.
Introduction "Thermal process engineering"
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In general, drying refers to the removal of moisture from solids, gases or liquids.
In the context of thermal process engineering, evaporation is understood to be the separation of a solvent from a solution.
Drying and evaporation
Drying curves for granular solids
Learning objectives/experiments
- influence of air temperature and humidity on drying intensity
- plotting of drying curves with constant external conditions
- determination of drying rate with different air parameters and different solid properties
- evaluation of drying processes using energy and mass balances
Concentration of temperature-sensitive solutions
Learning objectives/experiments
- fundamental principle of film evaporation for increasing the concentration of temperature-sensitive solutions
- investigation of the variables influencing the solid concentration in the solution
- influence of pressure and feed flow rate on the separating process
- influence of flow rate and pressure of the heating steam on the separating process
- investigation of the variables influencing the energy efficiency of the process
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Distillation is a unit operation that can be used to fractionate liquid mixtures. It utilises the different volatility of the components of the mixture to be separated.
Rectification is an application of distillation and its uses include fractionation of crude oil. In practice, this multi-stage distillation process is carried out in the form of countercurrent distillation (rectification) in a column.
Distillation / rectification
Continuous and discontinuous rectification with packed, sieve tray and bubble cap tray column, system control via PLC
Learning objectives/experiments
- investigation and comparison of sieve tray, bubble cap tray and packed columns
- in continuous mode
- in discontinuous mode
- in vacuum mode
- with different inlet heights for the feed flow
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Comparison of packed and sieve tray columns in rectification
Learning objectives/experiments
- investigation and comparison of sieve tray and packed columns
- in discontinuous mode
- in vacuum mode
- with different reflux ratios
- with different numbers of trays
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PLC controlled continuous rectification with packed and sieve tray column
Learning objectives/experiments
- investigation and comparison of a sieve tray column and a packed column
- in continuous operation
- with different pressures
- with different reflux ratios
- with different feed levels
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Absorption is used to remove one or more gaseous components from a gas flow using a solvent.
Adsorption is used to remove individual components from a gas or liquid mixture. The component to be removed is physically or chemically bonded to a solid surface.
Absorption and adsorption
Separating a carbon dioxide/air mixture by absorption in counterflow
Learning objectives/experiments
- investigation of the absorption process when separating gas mixtures in a packed column
- determination of pressure losses in the column
- representation of the absorption process in an operating diagram
- investigation of the variables influencing the effectiveness of absorption
Separation of oxygen from an air flow by absorption in a falling film column
Learning objectives/experiments
- investigation of the absorption process during the separation of oxygen from an air flow in a falling film column
- balance of the process
- determination of the mass transfer coefficient depending on
- volumetric air flow rate
- flow rate of the solvent water
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Basic principle of adsorption and desorption
Learning objectives/experiments
- fundamental principle of adsorption and desorption
- investigation of the variables influencing adsorption and desorption
- air flow rates
- air humidity and temperature
- bed height of adsorbent
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Adsorption of dissolved substances on activated carbon
Learning objectives/experiments
- recording of concentration profiles
- recording of breakthrough curves
- relationship between concentration profiles and breakthrough curves
- determining the mass transfer zone
- an adsorber’s mass balance
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Crystallisation is a unit operation in thermal process engineering, and is mainly used for separation and cleaning but also for shaping substances.
Compared to filtration, membrane separation processes remove much smaller substances, such as viruses and dissolved ions, from the water. The driving forces of the separation process are differences in concentration or pressure between the two sides of the membrane.
Crystallisation and membrane separation processes
Investigation of crystal growth in a fluidised bed
Learning objectives/experiments
- fundamental principle of cooling crystallisation
- investigation of the factors influencing crystal growth
- oversaturation
- saturation time
Membrane separation process for obtaining solvent from a salt solution, system control via PLC
Learning objectives/experiments
- assembly, cleaning and conservation of membrane modules
- fundamental principle of reverse osmosis
- permeate flow rate and retention dependent on
Liquid-liquid extraction involves using a liquid solvent to remove a liquid component from a liquid mixture.
Solid-liquid extraction allows soluble components to be removed from solids using a solvent.
Extraction
Separation of a two-component liquid mixture by extraction in counterflow with a solvent
Learning objectives/experiments
- transition of a component from a two-component liquid mixture into a solvent by extraction
- scale-up from beaker experiment to pilot plant scale
- enrichment of transition component in extract by distillation
- evaluation of separation processes via concentration measurement and mass balances
- influence of different experimental options on separation processes
Continuous and discontinuous extraction of the soluble components of a solid
Learning objectives/experiments
- fundamentals of solid-liquid extraction
- demonstration of solid-liquid extraction as a continuous and discontinuous process
- investigation of 1-, 2- and 3-stage processes
- influence of solvent flow rate and temperature on the extraction process
- influence of extraction material feed rate and extractor revolving speed on the extraction process
Mass transfer is one of various basic processes. These are, for example, drying processes, absorptions and adsorptions. Mass transfer is described with the individual mass transfer processes in a similar way to heat transfer processes.
Mass transfer
Use of Fick’s law
Learning objectives/experiments
- fundamentals of diffusion: Fick’s law
- derivation of the calculation formula for the diffusion coefficients for the given experimental conditions
- determination of the diffusion coefficient for the mass transport in gas
- determination of the diffusion coefficient for the mass transport in liquid
