environmentally benign chemical processeskkft.bme.hu/attachments/article/107/ebchemp_unit... ·...
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Environmentally benign chemical
processes
Typical unit operations and equipments
Erika Vági, Edit Székely
BME, Department of Chemical and Environmental Process Engineering
Schedule6 Feb. E. Vági: Introduction, Refreshing the basics.
13 Feb. E. Vági: Green chemistry metrics
20 Feb. E. Vági: IPPC, BATs, production of nitric acid
27 Feb E. Vági: Vacuum technologies6 March M. Test 1 (20 minutes) + Johannsen: Supercritical fluids 1. 13 March M. Johannsen: Supercritical fluids 2.
20 March – SPRING HOLIDAY (DAY OFF)
27 March M. Johannsen: Supercritical water oxidation, waste water treatment
3 Apr E. Vági: Test 2 (20 minutes) + Waste water treatment, purification strategies
10 Apr M. Johannsen: Membrane technologies
17 Apr E. Vági: Distillation, azeotropes
24 Apr E. Vági: Test 3 (20 minutes) + Presentations of BATs
1 May – LABOUR DAY (DAY OFF)
8 May – Dr. András Kovács – Biodiesel
15 May – Final lecture, repetation of test
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Requirements – during term
• Attendance: min. 70% at lectures;
• VOC /BATs presentation will be given by individually and accepted (if excellently done half mark extra is offered).
• 3 mid term tests (20 minutes each) – min 50% of 2 is required for the signature. Over an average 80% the final mark is offered (80-89% - 4; 90-100%- 5). 3
Requirements – during term
• Download the slides of the lectures time totime from the website: http://kkft.bme.hu/en/education/subjects/envchemproc
• Slides might be useful to structure your knowledge, but are not enough!
• Lecturers: Edit Székely, Erika Vági, Monika Johannsen (TU Hamburg-Harburg) and András Kovács
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Requirements - exams
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• Students having valid signature may take a written or oral exam during the examination period.
• Application for the exams is only possible via the Neptun system.
• In case of questions please contact Edit Székely ([email protected]) or Erika Vági ([email protected])
Aim of the course, topics
• To gain a general overview how the decide between possible synthetic routes and processes taking into consideration the environmental aspects.
• To familiarize with innovative/modern technologies as membrane separations, supercritical fluids, vacuum and high pressure separations etc.
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Unit operations
1. Mechanical separations
2. Heat transfer operations
3. Equilibrium mass transfer separations
4. Non-equilibrium stage separations
5. Chemical modifications
6. Biochemical modification
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1. Mechanical separations
• Precipitation• Sedimentation• Filtration• Flotation• Centrifugation• Electrostatic separation• Emulsion separation• Magnetic separation• Mechanical expression• Etc.
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Precipitation
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Filter press
Treated stream
Settling tank
Balance tank
Solid for recovery
/disposal
pH adjustment and flocculant
addition Feed stream
Sedimentation
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Sedimentation with cyclone
16DISA high-efficiency Cyclone
Air flotation
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Filtration – conventional multi medium sand filter
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Filtration
• Driving force is the pressure difference
• Various filtration media
• Typically a batch operation
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Filtration – rotary vacuum filter
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Centrifugation, decanter
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Emulsion separation
• Demulsification: chemical or physical
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Cold pressing
2. Heat transfer operations
• Heat exchangers
– Tube in tube (shell and tube)
– U-tube
– Spiral
– Plate
• Evaporators
– Robert evaporators
– Falling film evaporator
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• in smaller plants• in case of high pressure
Shanghai Ritai Medicine Equipment Project Co., Ltd.
Heat exchangers
26http://www.answers.com
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http://www.answers.com
Diabon
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Spiral heat exchangers
http://www.alfalaval.com
• Compact,
• Big relative surface area,
• Less viscous liquids of
condensation.
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Plate heat exchangers
Alfa-Laval - Canaley Process Equipments Co.
Evaporation, traditional
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Evaporation, falling film
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A feedB vapourC concentrateD steamE condensate
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Multi-effect evaporator in vegetable oil production
3. Equilibrium diffusional separations
• Distillation, rectification
• Absorption
• Extraction
• Adsorption
• Evaporation
• Crystallization
• Drying
• Etc.33
Distillation, rectification
• Major separation process for homogeneous liquids of two or more components.
• Separation is based on the difference in boiling points (volatility).
• No additional chemicals are needed, but energy requirement is relatively high.
• In a large number of separation task it is the most economical option.
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Bubble point – dew point curves and the equilibrium curve
mixture of benzene and toluene at atmospheric pressure
Batch distillation
Distillation column
Absorption
• Based on distribution ratio between gas and liquid streams
• Typical applications: gas washers, columns.
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http://www.separationprocesses.com/Absorption/GA_Figures/Fig115a.gif
Liquid-liquid extraction
41mixer settler
Solid-liquid extraction, Crown model III
Adsorption
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LES: length of equilibrium sectionLUB: length of unused bed
Drying
Three basic methods of heat transfer are used in industrial dryers in various combinations: convection, conduction and radiation.
Drying – fluidized bed dryer
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Membrane separations
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Schematic drawing of membrane separation (cross-flow filtration)
Feed
Permeate
Membrane
Retentate
Stirred tank reactors (Pfaudler, Germany)
• 300-15 000 gallon
(1-60 m3) volume
• Clamp top
• 5-500 gallon (0.02-2 m3) volume
Tubular reactors (UHDE, Germany)• Used in petrol industry
• First reactor (1955):- 24 mm Ø
- 1600 bar
- 10.000 tons/year
• Current reactors: - 70-90 mm Ø - 3600 bar
- 300.000 tons/year
Multi-tubular reactor (Oita, Japan)
Crystallisation
• Crystallisation is the formation of solid particles within a formerly homogeneous phase.
• Crystallisation from liquid solution is the most important industrially.
• Solidification from a liquid melt by freezing is also used for purifying some certain materials.
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Formation of crystals
• In the formation of a crystal two steps are required: the birth of new particle called nucleation and growth of this particle to macroscopic size.
• The final particle size and particle size distribution of the product are largely affected by the degree of supersaturation and the crystallisation technique applied.
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NaCl-crystal production
52J. H. ter Horst et al. Fundamentals of Industrial Crystallization (2015)
A cascade of three forced-circulation crystallizers in sequence, with external heat exchanger and circulation pump (with heat integration).
Thank you for your kind attention!
Notes for exams/ tests (from the website):
- Technologies.pdf
- Unit operations.pdf