PDF Continuous Rectification - جامعة الملك عبد العزيز

King Abdulaziz University

Faculty of Engineering, Rabigh

Dep. of Chemical & Mat. Engineering

Continuous Rectification

Procedure

1. Use caution avoid contacting hot surfaces.

2. Open cooling water inlet.

3. Set water flow rate at 150 - 200 L/h.

4. Turn main switch ON and turn controller setting to

"Local".

5. Open control software. On "Chart" tab, click

"Settings" and choose an appropriate path for saving data.

6. Check the liquid level in the evaporator; if it's below 6 L then

a) Prepare a mixture of 10-15 wt% ethanol in distilled water.

b) If the evaporator temperature is less than 30 °C, pour directly to the evaporator.

c) Otherwise, add it to one of the feed tanks, open the feed line valve and feed tank

bottom valve, and turn on the pump at 100%.

7. Turn on the heater at 100% (4000 W).

8. When column pressure drop starts to rise,

gradually reduce heater power to stabilize column pressure drop of 30-40 mbar.

9. It is critical not to exceed about 45 mbar to avoid reflux backup after the phase separator tank.

10. Keep reflux at 100% until steady state is achieved.

11. To estimate ethanol composition in the distillate tank,

a) Clean, dry, and tare the volumetric flasks.

b) Fill the flask with sample.

c) Determine the density and temperature of the sample, then estimate ethanol

composition from the provided density- concentration tables.

d) Empty the flask back to the distillate tank after measurement.

12. Columns can be operated at atmospheric and vacuum modes with different

a) reflux ratios

b) feed preheating

c) numbers of plates (sieve plate column) d) feed position (sieve plate column)

13. Corresponding concentration and temperature profiles can be plotted.

14. Turn off heater and main power switch.

15. Close cooling water valves.

16. Return all collected samples and drain all tanks into the feed tank (Tank VI).

Objectives

• Sieve plate and packed columns in batch, continuous and vacuum modes with different

• reflux ratios

• numbers of plates (sieve plate column)

• feed position (sieve plate column)

• feed preheating

• Concentration, temperature profiles and number of theoretical plates using the McCabe-Thiele diagram

Total Mass Balance

𝑚

_{𝑆𝑡𝑎𝑟𝑡}

= 𝑚

_{𝑇.𝑝𝑟.}

+ 𝑚

_{𝐵.𝑝𝑟.}

+ 𝑚

_{𝐵.𝑝𝑟.,𝐸𝑣𝑎𝑝}

+ 𝑚

_{𝐸𝑛𝑑,𝐹𝑒𝑒𝑑}

Ethanol Balance

𝑚_{𝐸,𝑆𝑡𝑎𝑟𝑡} = 𝑚_{𝐸,𝑇.𝑝𝑟.} + 𝑚_{𝐸,𝐵.𝑝𝑟.} + 𝑚𝐸,𝐵.𝑝𝑟.,𝐸𝑣𝑎𝑝 + 𝑚_{𝐸,𝐸𝑛𝑑,𝐹𝑒𝑒𝑑} 𝑚_{𝐸,𝑇.𝑝𝑟.} = 𝑚_{𝑇.𝑝𝑟.} ∙

𝜒

_{𝐸,𝑇.𝑝𝑟.}

Technical Data Columns

• internal diameter: 50mm

• height: 780mm Feed pump

• max. flow rate:

200mL/min Water jet pump

• final vacuum: ~ 200mbar Tanks

• feed: ~ 5L

• bottom product: ~ 4L

• top product: ~ 1.5L

• phase separation: ~ 0.5L Heat transfer surfaces

• feed preheating/bottom cooling: ~ 0.03m²

• top product condenser: ~ 0.04m²

1. evaporator with column, 2. bottom heat exchanger, 3.

bottom product tank, 4. feed tank, 5. feed pump, 6. top product tank, 7. feed, 8. reflux, 9. condenser, 10. phase separation tank, 11. water jet pump, 12. solvent tank; F.

flow rate, L. level, P. pressure, PD. differential pressure,

T. temperature; dotted, blue line: cooling water

King Abdulaziz University

Faculty of Engineering, Rabigh

Dep. of Chemical & Mat. Engineering

Solid-Liquid Extraction

6. Turn on heating element W1 and set solvent temperature to 30 °C

7. The extraction material is sprayed throughout the experiment (~30 to 45 min) and is not

replaced and obtain concentration development in extract.

Three stage - counter current - continuous process

1. Synchronize speed of feeder and extractor

(material depth ~ 40mm per cell). The filling

hopper should be filled with a sufficient quantity of extraction material.

2. Solvent flow rate should be > 6L/h.

Single stage process

1. Set valve position V1 and V2 to 1 stage.

2. Turn on process pump P1 and set solvent flow rate 15.5 L/h.

3. Turn on heating element W1 and set solvent temperature T1 at 30 °C.

Two stage process

1. Set valve position V1 and V2 to 2 stages.

2. Running 1 stage process settings, turn on and adjust pump P2, turn on heating element W2 and set T2 at 30°C

Three stage process

1. Set valve position V1 and V2 to 3 stages.

2. Running 2 stage process, turn on and adjust process pump P3.

3. Turn on heating element W3 and set solvent temperature T3 at 30 °C.

Solvent temperature - extraction performance 1. Set according to the 1 stage experiment.

2. When concentration is no longer rising at

measuring point C4, set the solvent temperature T1 to 30 °C.

3. When the concentration at C4 becomes constant increase temperature T1 to 45 °C.

4. Obtain concentration development in extract at different temperatures.

Solvent flow rate - extraction performance 1. Set according to the 1 stage experiment.

2. Turn on P1 and set solvent flow rate 8 L/h.

3. Turn on heating element W1 and set solvent temperature T1 at 30 °C.

4. When concentration does not change at C4, set flow rate to 11.5 L/h.

5. When the concentration at C4 becomes constant increase flow rate up to 15.5 L/h.

6. Repeat by increasing solvent flow rate up.

7. Obtain concentration development in extract at different solvent flow rate.

𝑀𝑎𝑠𝑠 𝑓𝑙𝑜𝑤 𝑟𝑎𝑡𝑒 𝑜𝑓 𝑡ℎ𝑒 𝑒𝑥𝑡𝑟𝑎𝑐𝑡

= 𝑐𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛 × 𝑠𝑜𝑙𝑣𝑒𝑛𝑡 𝑓𝑙𝑜𝑤 𝑟𝑎𝑡𝑒

Objectives

• Solid-liquid extraction with 1, 2 and 3 stages (continuous and batch)

• Effect of solvent flow rate, temperature, extraction material feed rate and extractor revolving speed

Procedure

1. Set the master switch to “ON”.

2. Make sure that the push buttons for pumps, extractor and material feeder are all OFF.

3. Make sure that the rocker switches for the heaters are at “0"

position.

4. Connect PC and the unit using USB cable and start the software.

Extraction performance for single stage batch process

1. 70g of extraction material is weighed out and added to the cell (this corresponds to material depth of approximately 40mm)

2. The extractor is turned using the speed adjuster until the cell is centrally below the solvent feed for the 1st stage.

3. The extractor drive is then turned off.

4. Set the valve position V1 and V2 to 1 stage.

5. Turn on process pump P1 and set solvent flow rate 15.5 L/h.

Technical Data Extractor

• 9 cells

• rotor diameter: ~ 200mm

• speed: ~0-9h^-1 Spiral conveyor

• max. feed rate: ~ 20L/h Peristaltic pumps

• max. flow rate: ~ 25L/h at

300min^-1 Heaters

• power: ~330W Tanks

• extraction material: ~ 5L

• extraction residue, solvent, extract: each ~20L

B1. solvent tank, B2. extract tank, B3. extraction residue tank, P.

pump W. heater, H1. revolving extractor, X1. material feeder,

C1./C2./C3. stages conductivities, T1. fresh solvent temperature, T2./T3./T4. stages temperatures, F. solvent flow rate, V1./V2./V3.

stage extraction valves

King Abdulaziz University

Faculty of Engineering, Rabigh

Dep. of Chemical & Mat. Engineering

Liquid-Liquid Extraction

3. Add slowly 4500g of rapeseed oil to the feed tank B5.

4. Circulate feed for 25min and stop P2.

5. Position 3-way ball valves for batch mode.

6. Open V30 and V4 for feed return.

7. Close V3 for solvent return.

8. Start solvent pump P1. If there are suction

problems, vent suction hose while opening V27 briefly.

9. Adjust solvent flow to about 80mL/ min using V1.

10. Start P2 and set feed flow to about 800mL/min using V2.

11. As the extraction column K1 fills up, close V30 as liquid starts to come out.

Extraction

1. Increase solvent flow ~400mL/min by V1.

2. Open V3 to have feed flow ~ 800mL/min.

3. Maintain phase boundary at 1/2 of the extraction column height by adjusting V3.

4. After every 20min, measure density by taking samples from V21.

5. Empty sample into B1 after measurement. After 180min of extraction time, stop pumps P1 & P2.

6. Close V1-V4 and open V30.

7. Open V3 to route solvent back to B1.

8. Close V3 as soon as the phase boundary reaches the base of the extraction column.

9. Collect feed from the extraction column into the measuring beaker by opening V28 and then

V29.

10. Drain measuring beaker into B5.

11. Calculate the efficiency of extraction.

Distillation

1. Pour 4000g of extract into flask D1.

2. Turn the main switch to "1".

3. Slowly open valve V11 (ambient pressure).

Move heating zone switch to "3".

4. Switch on heating mantle H1.

5. Release controller TIC1 and set SP at 95°C.

6. Open cold water inflow to W1 well before boiling starts.

7. Bring the residue in D1 to boiling point.

8. Ensure that the level in D1 is sufficient.

9. Interrupt distillation as soon as the vapour temperature T2 reaches the value of 98°C.

10. Switch off H1, close water supply to W1 and turn main switch to "0“.

11. Calculate the efficiency of distillation.

Cleaning

Rinse dirty components and lines with warm water, detergent and methylated spirits.

Objectives

• Separation of a liquid mixture by liquid-liquid extraction in counterflow operation

• Enrichment of extract by distillation (continuous or batch mode)

• Mass balances, effect of feed flow rates on the extraction efficiency

Procedure for Batch Operation

1. Pour 5000g tap water into solvent tank B1.

2. Pour 500g of ethanol into feed tank B5.

3. Close V2 in the feed inflow and start P2.

Technical Data Extraction column

• diameter: 40mm,

• height: 1.5m Distillation

• diameter: 30mm,

• height: 415mm

• heater power : 1200W Tanks

• feed and raffinate: 30L each

• solvent & extract:15L each

• top product (distill.):15L

• bottom tank (distill.): 5L Feed pump

• max. flow rate: 1L/min

• max. head: 80m Solvent Pump

• max. flow rate: 1.2L/min

• max. head: 10m Water jet pump

• final vacuum: ~ 200mbar

1. extraction column, 2. three-way valves, 3. water jet pump, 4.

solvent pump, 5. solvent tank, 6. top product tank (distillation), 7.

extract tank, 8. condenser with cooling water connection, 9.

distillation column, 10. feed pump, 11. feed tank, 12. raffinate tank, F. flow rate, P. pressure, T. temperature, L. level

Experimental conditions

Extraction of ethanol from rapeseed oil with water

• Mass fraction of ethanol in the feed: 10%

• Equal masses of feed and solvent: each 5000g

• Extraction time: 180min

• Solvent flow: 400mL/min

King Abdulaziz University

Faculty of Engineering, Rabigh

Dep. of Chemical & Mat. Engineering

Tray Drier

Theory

Immediately after contact between the drying media (wet solid) and the drying medium (hot air), the solid temperature adjusts until it reaches a steady state. If the solid is initially very wet the surface is essentially covered in a thin film of liquid which is considered to be unbound moisture. The solid temperature and the rate of drying may increase or decrease to reach the steady state condition. At steady state, the temperature of the wet solid surface is the wet bulb temperature of the drying medium.

Temperatures within the drying solid also tend to equal the wet bulb temperature of the air. However, lag between the movement of mass and heat result in some deviation. Once the media temperatures reach the wet bulb temperature of the air, the temperatures of the media and air become stable and the drying rate remains constant. This is the “constant rate drying”. The moisture is transported to the surface of the media by capillary forces and drying is limited only by the rate at which the heat is supplied. This period ends when the solid reaches the critical moisture content. The surface film of moisture over the solid has been reduced by evaporation to a point where any further drying causes dry spots to appear on the solid surface. Beyond the critical moisture content the surface temperature of the solid rises and the drying rate falls off rapidly. This is the “falling rate” period and can last for a significantly longer time than the constant rate period. This holds true even though the moisture removal may be less. The drying rate approaches zero as the moisture content reaches equilibrium. This is the lowest moisture content obtainable with the solid under the drying conditions used

Experiment:

To produce a drying and a drying rate curve for a wet solid being dried with air of fixed temperature and humidity.

Start-up (Pre-Heating & Zeroing load cells):

1.Make sure the unit is switched off and remove the three drying trays from the UOP8-MKII and set aside.

2.Turn on the UOP8-MKII tray drier using the main switch on the drier and also by clicking the “power on” button (so that it appears as button) on the Armsoft software.

3.Adjust the fan speed and louvre as required to achieve an inlet air velocity of 0.6m/s.

4.Note the temperature of T1 on the mimic diagram and enter this temperature as the ambient air temperature by clicking on the button on the mimic diagram.

5.Open the heater PID () and set to automatic with a set point of 55°C. Be aware that you must choose the option Automatic from the PID menu. Check that the preheat temperature sensor rises then stabilises approximately at the set point temperature.

Moisture Content & Time

0.000 0.050 0.100 0.150 0.200 0.250 0.300

0 5 10 15 20 25 30 35 40 45 47

Time (min)

X

Design of the device

King Abdulaziz University

Faculty of Engineering, Rabigh

Dep. of Chemical & Mat. Engineering

Evaporator

Summary:

Evaporation is a process used to concentrate aqueous solutions. It involves removing volatile solvent from an aqueous solution consisting of non- volatile solute by vaporization, in a vessel known as evaporator. Evaporation process begins with a liquid product and ends up with a more concentrated liquid as the main product. In some special cases, the evaporated, volatile component is the main product, for example in water desalination the vapors obtained by the evaporation process are condensed and used for drinking purposes.

Similarly the water that contains minerals is evaporated to obtain solid free water which can then be used in boilers, and for other special requirements. In all these cases the condensed water is the desired product. The use of multiple effect evaporators to increase progressively the concentration of a feed solution is widely adopted in the process industries. Evaporation is one of the principal methods used in the chemical industry to concentrate aqueous solutions.

This industrial equipment is usually large and complex so the Armfield evaporator has been specially designed to be of manageable scale in a student laboratory, while retaining the essential features of its industrial counterparts. Particular attention has been paid to the number and variety of experiments possible using the various evaporator modules available. Comprehensive exercises using Rising Film or Falling Film with Single Effect and Double Effect with various feed permutations can all be achieved. Connection to a computer greatly enhances the capability of the equipment with the data logging, data processing, help texts and control exercises included in the software package.

Theory

The equipment used for experimentation is

ARMFIELD RISING FILM EVAPORATOR

STEAM UOP20-X-STM. The heating medium is steam which is provided by a steam generator associated with the evaporation unit. The schematic of the experimental set up is shown in Fig. 1. The experimental unit is a floor standing tubular frame work for an evaporation system. It can be arranged as rising or falling film with single or double effect evaporation system. The unit is provided with full set of instrumentation. Thermocouples are available at twelve different points to measure the temperature of the product and heating fluid. The unit also comprises of a feed pump, vacuum pump, condenser, condensate vessel, temperature control feed preheater of 2kW and collection tanks.

Design of the device

King Abdulaziz University

Faculty of Engineering, Rabigh

Dep. of Chemical & Mat. Engineering

Filterability Index

Unit Description

The filterability index unit is used for demonstrating the filtering process through a porous media. It enables a water quality test to be made on a suspension to be filtered through sand or similar granular media. This unit utilizes a bed of granular material, normally sand, which can be chosen by the student to suit his own purposes.

The measurements taken with this unit enable a filterability index to be calculated which has significance in deep bed filter performance.

The unit is a bench-top unit composed of a feeding tank, where the initial solution of water with solids in suspension is placed. During the normal operation, the tank is communicated with the sand filter upper part, through a pipe of 10 mm diameter. The filter lower part is communicated with the flowmeter. A regulation valve located at the flowmeter allows to change the flow which passes through the filter. The fluid pressure is obtained by means of the gravity, because the feeding tank is placed in high. The pressure is measured by a manometer. The filter cartridge is easily removable, so it allows to study the difference between different media, both in compositions and in mesh. This unit, in addition to students teaching and training, also can be used in routine control at water purification works, or at water treatment works which employ tertiary filtration.

Some practical some practical possibilities of unit

1) Study of the filtration operation principles 2) Flowmeter calibration

3) Flow through permeable layers 4) Practice of sand filter cleaning 5) Filtration procedure

6)Calculation of Filterability Index from measurements taken

7) Deep bed filtration of suspensions with different particle layers

Design of the device

King Abdulaziz University

Faculty of Engineering, Rabigh

Dep. of Chemical & Mat. Engineering

Plate and Frame Filter Press

Unit Description

Arrangment of filter plates in frame filter press

Fundamental principles

Cake filtration is a mixture of surface and deep bed filtration.

The progress of filtration develops dynamically.

Metallic cloth or needle felting is used as the filter material, in some cases covered with a fine textile cloth. To support this, perforated plates or sieves are placed underneath.

The suspension fed onto the initially clean filter

material first of all flows almost completely through the filter material with only the largest solid

particles being retained. More and more solid particles are gradually deposited on the filter material, creating a filter cake that becomes increasingly thick.

The actual filtration only occurs when a sufficiently thick filter cake has formed. For the suspension to pass through this filter cake, there must be a

pressure difference between the feed side and the filtrate outlet side. This can be generated by:

– Hydrostatic pressure

– Creation of excess pressure on the suspension side (pressure filtration)

– Creation of a vacuum on the filtrate side (vacuum filtration)

Above a certain filter cake thickness, it must be removed. However, a residual layer is left behind so that there is no unclarified initial filtrate.

Cake filtration

King Abdulaziz University

Faculty of Engineering, Rabigh

Dep. of Chemical & Mat. Engineering

Venturi Scrubber System

Introduction

The SOLTEQ Venturi Scrubber System (Model: AP02) is designed and manufactured to a standard with emphasis on ease of use and operational safety for introduction of air pollution control by using venturi scrubber system to Chemical Engineering students. It consists mainly of transparent cylindrical venturi scrubber, a separation chamber, a water recirculation chamber, a powder-feeder system, an air blower, an outlet dust filter, and air flow meter.

The venturi scrubber system is made of a durable clear PVC with throat diameter of 32 mm and both convergence and divergence diameter of 101.6 mm. The separation chamber is also made of durable clear PVC with dimension of 0.6 m diameter and 2 m height. The chamber has a rectangular tangential inlet at the bottom of the venturi chamber. A mist eliminator is located at the top section of the chamber to prevent any water droplets from escaping. The water recirculation tank consists of a water tank, water pump, digital flow meter, pressure transmitter and a needle valve.

An air blower installed at the outlet is capable of drawing 222 m3/hr of air through the system. The air velocity is set by adjusting the speed of the blower which is controlled by an inverter. With the aid of a pneumatic vibrator, a valve is installed below the feed container to control the amount of dust particles sample introduced into the system. A pressure regulator is used to regulate the pneumatic vibrator.

Three digital differential pressure transmitters have been installed for measuring pressure drops across the bag house, venturi meter, and air flow rate. Student will demonstrate venturi scrubber operations by varying several parameters such as liquid to gas (L/G) ratio to estimate its effect on separation efficiency and verify the theoretical relationship between total pressure drop and air inlet velocity

Section Description of Venturi Scrubber

Schematic diagram of the Venturi Scrubber System

King Abdulaziz University

Faculty of Engineering, Rabigh

Dep. of Chemical & Mat. Engineering

Flow through Particle Layers

10. After filling the filter, carefully slide the filter crown on to the glass tube until its front end makes contact with the crown.

11. Ensure that the O-rings are correctly seated in order to protect them against damage.

12. After assembling the filter, install it back in its holder and tighten the knurled screws

again.

13. De-aerate hoses by opening both discharge valves and rinse the hoses with water until they are completely free of air bubbles.

14. Then close both discharge valves simultaneously.

15. Establish the hose connections for the inlet, outlet and pressure distributor.

16. Pressures drop (∆𝑝) is calculated from the difference in heights of water columns (∆ℎ) in the two glass tubes

∆𝑝 = 𝜌 𝑔 ∆ℎ Deposited layers (Fixed beds) Darcy’s equation

𝑄 = ∆𝑝𝐴

ߟ

_𝐿

𝑅

where 𝐴 is flow area, 𝑄 is volumetric flow rate, 𝑅 is hydraulic resistance and ߟ

_𝐿

is dynamic

viscosity

Carman-Kozeny modified Darcy equation as 𝑄 = ∆𝑝𝐴𝜀

³

𝑑

_𝑝²

ߟ

_𝐿

1 − 𝜀

²

𝐻𝐾

where 𝑑

_𝑝

is particle size, 𝐻 is bed height and 𝐾 is material constant.

Fluidized beds

∆𝑝 = 𝐻 1 − 𝜀 𝜌

_𝑝

− 𝜌

_𝐿

where 𝜀 is the bed voidage, 𝜌

_𝑝

is apparent

density of particles and 𝜌

_𝐿

is the density of the fluid

𝑅𝑒 = 42.86 1 − 𝜀 1 + 3.11 × 10⁻⁴𝐴𝑟 𝜀³

1 − 𝜀 ² − 1

𝐴𝑟 = 𝑔𝑑

_𝑝³

𝜌

_𝑝

− 𝜌

_𝐿

𝜈

²

𝜌

_𝐿

where 𝐴𝑟 is Archimedes number, 𝜈 is the kinematic viscosity and 𝑔 is the gravity acceleration

17. Drain the system of water and disconnect the manometers.

18. Remove the particle layers from the filter.

Objectives

• Flow properties of deposited layers and fluidized beds

comprising of different granular materials, sizes and layer heights

• Verification of Carman-Kozeny equation

• Onset of fluidization

Procedure

1. Fill a measurement beaker with 20 mL (𝑉

_𝐿

) of water.

2. Fill the measurement beaker with particles until a water layer is no longer visible.

3. Read the total volume of deposit and water (𝑉

_𝐿

+ 𝑉

_𝑆

).

4. Determine the porosity (𝜀 )

𝜀 = 𝑉

_𝐿

𝑉

_𝐿

+ 𝑉

_𝑆

5. Position the device on a flat surface in the vicinity of a drain and water connection.

6. Loose and remove the knurled screws on the filter crown.

7. Detach the hoses of manometer from the filter crown and base.

8. Withdraw filter out of its holder and detach filter crown from the filter tube by hand.

9. Place the filter base and glass tube on a level surface and fill the filter with particles until the required particle

deposition height has been attained. Read the height from the mounted scale.

Technical Data Test tanks

• length: 510mm

• inside diameter: ~ 37mm Filter medium

• thickness:2mm

• material: sintered metal Expansion tank

• capacity: ~ 4500mL

Fixed bed (A) and fluidized beds (B): 1. tube (particle layer), 2.

valve (flow rate), 3. inlet, 4. outlet, 5. expansion tank; P. pressure, F.

flow rate

King Abdulaziz University

Faculty of Engineering, Rabigh

Dep. of Chemical & Mat. Engineering

Depth Filtration

Introduction

The CE 579 unit is part of the 2E – ENERGY & ENVIRONMENT product area.

ENERGY

The ENERGY product area includes units involved with regenerative energies. Examples of these are photovoltaics, solar heat and water power.

ENVIRONMENT

Harmful substances are transferred and converted in the hydrosphere (water), the atmosphere (air) and the pedosphere (soil).

Water, soil and air are referred to as environmental compartments and are linked together by the global water cycle. In addition, the ENVIRONMENT area includes training on the topic of waste. The CE 579 is part of the water training area. This training area covers the most important basic processes in water treatment. The basic processes can be divided into three groups The choice of processes depends on the properties

of the substances to be removed from the water. Mechanical processes are used to remove insoluble substances (solids). By contrast, dissolved substances can be removed using biological or physical/chemical processes. If the dissolved substances are biodegradable, biological processes are used. On the other hand, if the dissolved

substances are not biodegradable, physical/ chemical processes are used. Filtration is a mechanical process that is very commonly used in water treatment. In terms of filtration, we can differentiate between:

• Surface filtration

• Depth filtration

Sand Filter