Labo III Appendix a Gunt Ce602e

Experiment Instructions CE 602

Discontinuous Rectification

07/2014

CE 602

DISCONTINUOUS RECTIFICATION

4 1 0 2 / 7 0 y n a m r e G l , e t t ü b s r a B , H b m G u a b e t ä r e G . T . N . U . G d e v r e s e R s t h g i R l l A

Experiment Instructions Please read and follow the safety regulations before the first installation!

Publication-no.: 918.000 00 D 602 02 (A)

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Table of Contents


1

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

2

Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.1 Equipment Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.2 Equipment Functions and Components. . . . . . . . . . . . . . . . . . . . . . . 4 2.2.1

Components for the Thermal Process . . . . . . . . . . . . . . . . . 4

2.2.2

Control Cabinet. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

2.3 Commissioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2.3.1

Preparing the System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

2.4 Shutting Down. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

3

Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 3.1 Health hazards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 3.2 Hazards for Equipment and Function . . . . . . . . . . . . . . . . . . . . . . . 11

4

Theory. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 4.1 Basic Principles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

5

4.1.1

Distillation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

4.1.2

Rectification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 5.1 Distillation Experiment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 5.1.1

Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

5.1.2

Test Results, Pure Distillation. . . . . . . . . . . . . . . . . . . . . . . 17

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5.2 Rectification Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 5.2.1

Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

5.2.2

Test Results, Rectification I . . . . . . . . . . . . . . . . . . . . . . . . 19

5.2.3

Test Results, Rectification II . . . . . . . . . . . . . . . . . . . . . . . . 20

5.3 Method with Vacuum, Vacuum Distillation. . . . . . . . . . . . . . . . . . . . 22 5.4 Notes on Further Experiments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 4 1 0 2 / 7 0 y n a m r e G l , e t t ü b s r a B , H b m G u a b e t ä r e G . T . N . U . G d e v r e s e R s t h g i R l l A

6

Appendix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 6.1 Technical Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 6.2 Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 6.3 Specimen Report Sheet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 6.4 Items Supplied. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

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1


Introduction

In physical-chemical engineering, liquid mixtures that consist of mutually soluble fluids are usually separated by thermal processes. The main processes used are distillation and rectification. The CE602 Discontinous Rectification can be used to thermally separate liquid mixtures for experimental purposes using these two processes.


The system consists of an electrically heated evaporator in which the initial liquid mixture is heated and evaporated. The steam rises through a column and is subsequently condensed in a water-cooled condenser. From here, all of the condensate can be drained off as the top product, or all or part of it can be returned to the column. A sieve tray column and a packed column are provided for use in experiments as required. A connection is fitted at the head of each column to allow the return of distillate. A glass filter pump can be used to generate a vacuum in the entire tube system for vacuumdistillation. The range of experiments covers the following areas: 





Batch operation with or without reflux to sieve tray or packed column Comparison of separation efficiency and separation quality between packed column and sieve tray column Vacuum distillation

The equipment has been designed to allow most operations to be observed. The system is for edu-

1 Introduction

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cational use in the field of thermal process engineering and apparatus construction. The CE 602 Discontinous Rectification it intended solely for educational purposes and not for industrial production.


1 Introduction

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2

Description

2.1

Equipment Layout 4


5

6

7

9 3

2

1

10

1 Evaporator

11

2 Column 3 Hand valve and flowmeter for cooling water

12

4 Differential pressure gauge 5 Condenser 6 Reflux divider 7 Vacuum gauge 8 Vacuum pump 9 Top product container 10 Control cabinet with system diagram

13

11 Water outlet 12 Hand valve for regulating the vacuum pump 13 Water inlet

Fig. 2.1

CE 602 Batch Distillation System, General View

2 Description

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2.2

Equipment Functions and Components

2.2.1

Components for the Thermal Process

The CE 602 Discontinous Rectification is used to separate homogenous liquid mixtures by distillation or rectification on an experimental scale. A mixture of ethanol and water is used in the experiments. 4 1 0 2 / 7 0 y n a m r e G l , e t t ü b s r a B , H b m G u a b e t ä r e G . T . N . U . G d e v r e s e R s t h g i R l l A

A steel tank with a built-in electric heater acts as an evaporator (1) for the liquids. On the front of the tank is a riser to indicate the liquid level. The evaporator can be filled through its top cap. A column (2) in which the mass separation takes place when the equipment is in operation is mounted on top of the evaporator. Either a packed column or a sieve plate column with 8 plates can be used. Fig. 2.2

Sieve plate column

The drop in pressure that occurs over the column can be measured with a differential pressure gauge (4). The steam passes along a tube at the top of the column into the water-cooled condenser (5). The distillate that collects here flows into the reflux divider (6) from where it can be drained off directly by means of a hand valve. By using two electrically operated valves, the distillate downstream of the reflux divider can be divided into reflux and top product with a defined reflux ratio which is controlled electronically. The reflux then returns to the system across the column head. The diverted top product flows into the top product tank (9).

Fig. 2.3

Packed column

2 Description

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The cooling water for the condenser must be supplied externally from a mains water supply. The cooling water volume can be read off the flowmeter (3). The flow can be controlled with the corresponding hand valve under the flow meter.


The residue which is enriched in the evaporator during the experiments is called the bottom product. It can be drained directly into a suitable vessel through a drain valve at the front of the evaporator.

Water outlet Water inlet Fig. 2.4

Water connections

A glass filter pump (8) is used to perform experiments with vacuum. This makes it possible to reduce the atmospheric pressure throughout the system. This pump is also operated with water from the mains water supply. The hand valve (12) is used to regulate the flow of water through the pump. The level of vacuum can be read off on the vacuum gauge (7). All switching and monitoring functions are provided by the electrical control cabinet (10).

2 Description

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DISCONTINUOUS RECTIFICATION Control Cabinet

The control cabinet contains all the switchgear necessary to control the system and conduct measurements.

14 Emergency Stop button 20

19 4 1 0 2 / 7 0 y n a m r e G l , e t t ü b s r a B , H b m G u a b e t ä r e G . T . N . U . G d e v r e s e R s t h g i R l l A

15 Reflux divider ON/OFF 16 Reflux ratio indicator in %

21

17 Display and measuring point selector for temperatures T1 - T12

22

18 Heater ON/OFF

18

19 Controller for head temperature T13 20 Heater indicator lamp

17

21 „Low Level“ warning lamp

16 15

23

14

24

Fig. 2.5

22 System Diagram 23 Reflux ratio selector 24 Master switch

Control cabinet, Front view

The following functions are available: 



A selector switch (17) for temperature measuring points T1 - T12 with display. The measuring points are selected simply by turning the knob Controls for the reflux ratio: 

ON/OFF switch (15)



Selector for reflux ratio 0 - 100%



2 Description

Reflux ratio display. Displays the % of distillate that is returned to the column.

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DISCONTINUOUS RECTIFICATION 

Heater controls: 








1 5 2

ON/OFF switch (18) The indicator lamp (20) lights up when the heater is on. „Low Level“ warning lamp (21) The evaporator tank is fitted with a level switch. If the evaporator does not contain at least the minimum amount of liquid, the heater cuts out automatically and the warning lamp lights up. Controller (19)for theheadtemperature T13. This is a continuous industrial controller whichthe usercan configureand program. The controller is set toa suitablebasicsetting at the factory. Furthersettings are not necessary. Please refer to the separate controller instructions for further information.

4

3

1

Actual value

2

Setting value

3

Operating buttons

4

„Manual operation“ indicator lamp

5

Unit

Fig. 2.6



Temperature Controller

Exit button

Arrow buttons

Setting temperature T13 on the controller

When it is switched on the controller is in normal display mode. Operating the „EXIT “ button toggles between the controller’s automatic and manual modes. The indicator LED (5) lights when the controller is in manual mode. In this mode the control ratio of the controller can be adjusted directly using the two „ arrow keys “.

PGM button

2 Description

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If the indicator LED (5) does not light up, the controller is in automatic mode. 1 5 2

4

In this mode the required setpoint can be adjusted using the two „ arrow keys “.

3


REMARK: The controller only updates the new setpoint after approx. 2 seconds! 1

Actual value

2

Setting value

3

Operating buttons

5

„Manual operation“ indicator lamp

6

Unit

Fig. 2.7

Temperature Controller

2 Description

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2.3

Commissioning

2.3.1

Preparing the System 








Ensure that all hose connections are secure and free from leaks Check the status of all hand valves, close valves if necessary Select the required column and mount it on the evaporator Fill the evaporator with a suitable test liquid. Make sure that the minimum liquid level is reached.

Warning! The heater will not activate if the evaporator is underfilled. Observe the „Low Level“ warning lamp min. 2 litres to ensure that the heater activates min. 5 litres to allow a meaningful experiment without the heater cutting out prematurely 

2.4

Open the water supply and provide a suitable runoff for the cooling water



Connect the unit to themains electricity supply



Switch off the system at the master switch

Shutting Down









2 Description

Shut off the water supply and isolate the system from the water main CAUTION: Allow the system to cool down for approx. 1 hour, erect a warning sign if necessary

Now drain the bottom tank Check the status of the hand valves to prevent spillage

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3


Safety The Instruction Manual in general and the safety information in particular must be read carefully before the equipment is used. The safety aspects and the safe and proper handling of the apparatus must be explained to the participants before any experiments commence.


3.1

Health hazards RISK of electric shock!

Only technically qualified personnel may open the control cabinet or work on the electrical equipment Unplug the system from the mains prior to opening the switch cabinet and working on the electrics. Protect theelectricalsystemfrom water andmoisture. DANGER of burns!

The evaporator, column and pipes get hot during experiments due to the nature of the process. Do not touch system components when in operation. When emptying the hot bottom product be sure to drain it into suitable heat-resistant containers and wear protective gloves at all times. DANGER, health risk!

Follow the appropriate hazard information and safety instructions when handling the chemicals which are used. This applies particularly when filling and emptying the system.

3 Safety

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3.2


Hazards for Equipment and Function WARNING!

The choice of chemicals for distillation and rectification is limited by the resistance of the materials used in the construction of the equipment. Use only those chemicals which do not attack 4 1 0 2 / 7 0 y n a m r e G l , e t t ü b s r a B , H b m G u a b e t ä r e G . T . N . U . G d e v r e s e R s t h g i R l l A



VITON,



PVDF,



PTFE and



stainless steel 1.4305!

WARNING!

The electrical components and the control cabinet must be protected from moisture and humidity and especially from aggressive media.

3 Safety

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4

Theory

4.1

Basic Principles

Distillation and rectification are thermal processes used to separate or purify liquid mixtures whose constituents are wholly miscible with one another.


Both processes work by the basic operations of evaporating a liquid and then condensing the resulting vapours. A e c n a t s b u s f o 1

When a liquid mixture AB, in which substance A has the fraction x1, is brought to the boil, it will give off steam. Substance A has a different fraction y 1 in the steam than it does in the liquid mixture AB.

1

0.8

0.6 0.52

y n m o a i t e c t s a r n F i

0.4

0.2

0 0

0.2

0.3

0.4

0.6

0.8

1

Fraction x1 of substance A in the liquid mixture

Fig. 4.1

Example of an Equilibrium Curve

If we enter the corresponding values for the vapour for all possible mixture ratios of AB in a diagram, we obtain the equilibrium curve. This curve indicates the mixture ratio of the steam given off by the boiling liquid. Equilibrium curves are different for different substance mixtures. The more the curve bends away from the diagonal in the diagram, the greater is the difference in the ratio of substance A to substance B in liquid and vapour. The collected condensate is therefore richer in low-boiling constituents compared with the initial mixture. The proportion of high-boiling constituents in the residual mixture is correspondingly higher. In distillation/rectification therefore, the vapour phase has a different mixture ratio than the liquid phase. This fact is the underlying principle of these processes.

4 Theory

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4.1.1


Distillation

In distillation, a liquid mixture is brought to the boil and the resulting vapour is drawn off and condensed. This condensed liquid is known as the distillate. The remaining mixture is the residue.

Evaporator 4 1 0 2 / 7 0 y n a m r e G l , e t t ü b s r a B , H b m G u a b e t ä r e G . T . N . U . G d e v r e s e R s t h g i R l l A

Condenser

Distillation apparatus consists of: 



Residue



Distillate

Fig. 4.2

Distillation, schematic

an evaporator to heat the initial mixture and collect the high-boiling component (residue). a condenser to condense the low-boiling component (distillate). one or more vessels in which to collect the distillate

Distillation does not produce a complete separation of the initial mixture. It just divides the initial mixture into two mixtures with different mixture ratios. In simpledistillation, all of the distillate is collected. There is also the process in which the condensate is collected in different vessels, known as fractions, as distillation time passes. This is known as fractional distillation. To protect temperature-sensitive substances during distillation, their mixtures are distilled in a vacuum where boiling points are lower. This method is known as vacuum distillation. Essentially vacuum distillation works exactly like conventional distillation, except that a vacuum pump downstream of the condenser maintains a vacuum throughout the system.

4 Theory

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4.1.2

Rectification

The result of the separation obtained by distillation is not sufficient in all cases. y4

To improve separation, the collected condensate should be distilled again. This process should be repeated until the required material is satisfactorily purified. Multiple-stage distillation of this type is expensive and energy-intensive.

y3

y2

y1


Rectification is therefore used. x1

Fig. 4.3

x2

x3

x4

x5

Equilibrium diagram for multiple-stage distillation

Top

Top product

In rectification, the released vapour is first passed through a vertical tube called the column before it reaches the condenser. Instead of all of the distillate collected in the condenser being drawn off straight away, part of it is returned to the column as the so-called reflux. The difference between rectification and distillation is that the rising vapour mixture and returning condensate flow counter to one another. The process is therefore also known as counterflow distillation.

Column

Reflux

Bottom Bottom product

Fig. 4.4

4 Theory

Rectification, schematic

The returned condensate now runs down the column and is forced into contact with the rising vapours on suitable internals. The result is an exchange of material and heat between the rising vapours and the falling liquid. The high-boiling component condenses first from the rising vapours. The resulting condensation heat causes more low-boiling component to evaporate in turn. The result is that the liquid flowing back to the bottom of the column is enriched with high-boiling components. The vapours at the top

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of the column are correspondingly richer in low-boiling components. The exchange of materials that occurs in the column can be intensified by increasing the contact area over which the exchange can take place. Columns therefore contain suitable internalsW0 such as trays or packed beds which increase this contact area.


Packing pieces are small, regularly shaped pieces of plastic, ceramics or metal. There is a very large number of different packing pieces to suit a wide variety of separation applications. At the top of the column, the distillate is divided into one part reflux and one part top product. The ratio

Condenser

Column head Reflux Reflux divider

Aftercooler

Column with internals

Top product (low-boiling)

Evaporator Column bottom

Initial mixture

Bottom product (high-boiling) Aftercooler

Fig. 4.5

4 Theory

Rectification system, schematic representation

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of reflux to top product is called the reflux ratio. It is an important parameter of the column. Liquid mixtures can be almost totally separated by rectification, especially mixtures whose equilibrium curves deviate only slightly from the diagram diagonal.


4 Theory

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5

Experiments

5.1

Distillation Experiment

5.1.1

Preparation 




Filler







Fig. 5.1

Filling the Evaporator 







5 Experiments

Prepare theapparatus asdescribedinChapter 2.3 Prepare approx. 5 litres of test mixture: Ethanol: approx. 20% (weight per cent), Water: approx. 80% (weight per cent) Determine the specific gravity of the solution and note it Fill the evaporator with the test mixture Set the reflux ratio to zero in order to run pure distillation Supply the condenser with cooling water and set l the flow rate to approx. 150 ... 200 / h Switch on the heater at the controller (manual mode) and select 100% power. Now set the valves on the reflux divider so that collecting distillate flows off to the top product vessel. Determine and note the specific gravity of the distillate, and compare with the concentration of the initial product After the cooling-down time, take a sample of the residue in the evaporator. Determine and note the specific gravity of the residue, and compare with the concentration of the initial product and of the distillate.

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6

Appendix

6.1

Technical Data

Overall Unit:

l x w x h:

1300 x 750 x 2100 mm

Weight:

180 kg

Power supply: 3 x 400 V / 50 Hz Alternatives optional, see rating plate Cooling water:


Sieve tray column:

30 ... 400 ltr/h

Ø x h: Material:

50 x 765 mm Stainless steel Borosilicate Glass

Number of trays Packed column:

8

Ø x h: Material

50 x 765 mm Stainless steel

Column packing Ø x h: Material Evaporator:

Heating power Safety temperature limiter Capacity Minimum fill Cutoff volume

6 Appendix

Raschig rings 4 x 4 mm Soda glass max. 4.0 kW 110 °C max. 12 ltr min. 5 ltr ~ 3 ltr

Test mixture:

Ethanol / Water

~ 20 : 80 %

Capacities:

Top product vessel

approx. 1.5 ltr

Reflux divider

approx. 0.5 ltr

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6.2


Tables

Density andcontent of aqueous ethanol solutions relative to water 15 °C = 1.000 (according to Windisch) 0,00

Density


Fig. 6.1

6 Appendix

g / l

Weight %

Vol. %

0,00

0,00

0,00

1

0

0

0

0,995

2,73

3,42

27,2

0,99

5,76

7,18

57

0,00

0,985

9,2

11,41

90,6

0,98

13,08

16,14

128,1

0,975

17,23

21,16

167,9

0,97

21,32

26,03

206,6

0,965

25,09

30,49

241,9

0,96

28,52

34,47

273,6

0,955

31,66

38,06

302,1

0,95

34,56

41,33

328

0,945

37,28

44,35

352

0,94

39,86

47,18

374,4

0,935

42,34

49,85

395,6

0,93

44,75

52,39

415,8

0,925

47,09

54,84

435,2

0,92

49,39

57,21

454

0,915

51,65

59,5

472,2

0,91

53,88

61,73

489,9

0,905

56,09

63,91

507,1

0,9

58,27

66,03

524

0,895

60,45

68,12

540,5

0,89

62,61

70,16

556,7

0,885

64,75

72,15

572,6

0,88

66,89

74,11

588,1

0,875

69,01

76,02

603,3

0,87

71,12

77,9

618,2

0,865

73,21

79,73

632,7

0,86

75,29

81,52

646,9

0,855

77,35

83,27

660,8

0,85

79,4

84,97

674,3

0,845

81,43

86,63

687,5

0,84

83,43

88,23

700,2

0,835

85,41

89,79

712,6

0,83

87,35

91,29

724,4

0,825

89,26

92,72

735,8

0,82

91,13

94,09

746,6

0,815

92,96

95,38

756,9

0,81

94,73

96,61

766,7

0,805

96,46

97,76

775,8

0,8

98,13

98,84

784,4

0,795

99,76

99,86

792,4

0,79425

100

100

793,6

Density of aqueous alcohol solutions

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Fig. 6.2

6 Appendix

System Diagram

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6.3


Specimen Report Sheet

Experiment :

Experiment No. :

Comments :

Date :

Test mixture 4 1 0 2 / 7 0 y n a m r e G l , e t t ü b s r a B , H b m G u a b e t ä r e G . T . N . U . G d e v r e s e R s t h g i R l l A

Sp. gr. of the mixture

g / ml

Concentration

%

Heating power

%

Top temperature T 13

°C

Cooling water temp. at inlet T 11

°C

Cooling water temp. at outlet T 12

°C

Cooling water flow rate

l/h

Reflux ratio

%

Differential pressure over the column Test duration Amount of distillate obtained Distillate density Distillate concentration

6 Appendix

mbar min ml g/ml %

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6.4


Items Supplied

1

System complete in steel trolley on castors

1

Sieve tray column

1

Packed column

1

Instruction manual


6 Appendix

27

Labo III Appendix a Gunt Ce602e

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