lab presentation

LAB PRESENTATIONSEPARATION PROCESS

2

GROUP 14: TRAY DRYER

MOHD SYAZWAN BIN MOHD PATANI 13170MUHAMMAD AZAM BIN ARIFFIN 13180 NUR AINDA BINTI

MOHD BUKHARI 13307 NURYIHAN CHAPAKIYA 11800

MUHAMMAD IZZUDDIN BIN MOHAMMAD ZAKI 13239MUHAMMAD SYAHIR AIZAT BIN MOHD KHAIRUDDIN 13257

LAB DEMONSTRATOR: MR ZAKIR

ABSTRACT

Introduction Objectives Experimental procedures Results Conclusion

INTRODUCTION

DRYING Reducing moisture

content Method of preserving

food Microorganisms

unable to grow Enzymes promote

undesired changes in the chemical composition of the food cannot function without water

APPLICATIONS Industrial spray

dryer Steam tube dryer Rotary dryer Vertical thin film

dryer Freeze dryer Fluid bed dryer

INTRODUCTION

EFFECT OF PROCESS VARIABLE ON CONSTANT RATE PERIOD

Velocity Gas temperature Gas humidity Effect of thickness

of solid being dried Experimental effect

of process variable

Tray Dryer (Model: BP772)

Student laboratory training programmes

Resembles the most commonly used industrial methods of drying solids

INTRODUCTION THEORY

The drying rate of wet solid in air changes throughout the drying period since the controlling factors are different for each major section of the drying rate curve. However, many wet different for each major section of drying rate is essentially constant and: Rc a h v ( Tv – Ti )

Where,Rc = drying rate during constant rate period

hv = total heat transfer coefficient (essentially convective)

Tv = temp. of the drying gas (dry bulb)

Ti = temp. of liquid/gas interface (wet bulb)

Extensive experimental results (Sebord 1993) suggest that for air drying:hv a Gv 0.8

where G = air mass velocity Moisture content = (Weight of liquid / Weight of dry sand)

PROCEDURES

Repeat the experiment and switch heater power to point B

Time (min)

Dry bulb temperature

, Tv (oC)

Relative humidity

(%)

Wet bulb temperature

, Ti (oC)

Tv -Ti

(oC)Wet sand

weight (kg)

Moisture content,

Xe

Drying Rate

(kg/min)

RESULT AND CALCULATION

sanddry ofWeight

sanddry ofeight sand wet ofeight X content, Moisture e

WW

THv

v

H

vG

Gh

TTh

R

H

H

ic

33

8.0

w

1056.41083.2

1

02.0

60

Time (min)Dry bulb

temperature, Tv (oC)

Relative humidity (%)

Wet bulb temperature, Ti (oC) Tv -Ti (oC) Wet sand

weight (kg)Moisture

content, XeDrying Rate (kg/min)

0 39.1 97.47 38.2 0.9 0.4815 0.0067 0.0028827

3 39.1 97.40 38.3 0.8 0.4806 0.0048 0.002528

6 39.4 97.39 38.6 0.8 0.4800 0.0036 0.002526

9 39.5 98.35 38.7 0.8 0.4795 0.0025 0.002524

12 39.5 98.65 38.7 0.8 0.4791 0.0017 0.002523

15 39.5 97.98 38.7 0.8 0.4788 0.0010 0.002525

18 39.5 97.66 38.7 0.8 0.4785 0.0004 0.002525

21 39.5 97.66 38.7 0.8 0.4783 0.0000 0.002525

0 3 6 9 12 15 18 210

0.0010.0020.0030.0040.0050.0060.0070.008

Moisture content, Xe against Time (min)

Time (min)

Mois

ture

conte

nt,

Xe

0 0.0004 0.001 0.0017 0.0025 0.0036 0.0048 0.00670.0023

0.0024

0.0025

0.0026

0.0027

0.0028

0.0029

0.003

Graph of Drying Rate vs Moisture Content

Moisture Content, Xe

Dry

ing R

ate

(kg/m

in)

Experiment A: Effect of air temperature •Heater power control = Point AAir velocity = 11.3 m/sWeight of dry sand = 0.4783 kg

Time (min)

Dry bulb temperature, Tv

(oC)


Wet bulb temperature, Ti

(oC)

Tv -Ti

(oC)Wet sand

weight (kg)Moisture

content, Xe

Drying Rate (kg/min)

0 39.0 95.51 37.9 1.1 0.4812 0.0061 0.0034813 44.6 95.87 43.1 1.5 0.4802 0.0040 0.0047036 46.9 95.51 45.4 1.5 0.4795 0.0025 0.004699 48.0 95.69 46.6 1.4 0.4790 0.0015 0.00436

12 48.7 96.55 47.3 1.4 0.4785 0.0004 0.0040515 49.0 97.06 47.7 1.3 0.4783 0.0000 0.0040518 49.0 97.06 47.7 1.3 0.4783 0.0000 0.00405

0 3 6 9 12 15 18 210

0.001

0.002

0.003

0.004

0.005

0.006

0.007


Time (min)

Mois

ture

conte

nt,

Xe

0 0.0004 0.0015 0.0025 0.004 0.00610

0.001

0.002

0.003

0.004

0.005



Dry

ing R

ate

(kg/m

in)

•Heater power control = point BAir velocity = 11.3

m/sWeight of dry sand = 0.4783

kg

Time (min)

Dry bulb temperature, Tv

(oC)


Wet bulb temperature, Ti

(oC)

Tv -Ti

(oC)Wet sand

weight (kg)Moisture

content, Xe

Drying Rate (kg/min)

0 41.1 98.32 40.3 0.8 0.4810 0.0056 0.03425

3 38.2 98.79 37.7 0.5 0.4797 0.0029 0.02260

6 37.3 99.12 36.8 0.5 0.4791 0.0017 0.02304

9 37.2 98.53 36.6 0.6 0.4787 0.0008 0.02771

12 37.0 99.13 36.5 0.5 0.4783 0.0000 0.02318

15 37.0 99.13 36.5 0.5 0.4783 0.0000 0.02318

0 3 6 9 12 15 18 210

0.001

0.002

0.003

0.004

0.005

0.006


Time (min)

Mois

ture

conte

nt,

Xe

0

0.00

0800

0000

0000

0001

0.00

17

0.00

29

0.00

560

0.015

0.03



Dry

ing R

ate

(kg/m

in)

Experiment B: Effect of air velocityAir velocity = 39.6m/sWeight of dry sand = 0.4783 kgFan velocity control: Point B

DISCUSSIONS

In our experiment, we focus here:-

Experiment 1 : Effect of temperature on the drying rate (Fixed air velocity)Experiment 2 : Effect of air velocity on the drying rate (Fixed temperature and humidity)

Experiment 1AHeat power control: Point AAir velocity = 11.3 m/s

Experiment 1BHeat power control: Point BAir velocity = 11.3 m/s

Heat supply ↑ Rate of drying ↑Theoretical drying rate curveConstant period Falling periodCritical moisture content

Experiment2AHeat power control: Point BAir velocity = 11.3 m/sExperiment2BHeat power control: Point BAir velocity = 39.6 m/s

Velocity ↑ rate of drying ↑For moisture content, it is inverse proportional to timeMoisture content reduced during the drying process, until the moisture of solid is equal equilibrium moisture

Exp1B takes less time for moisture content to become zero that Exp1A air temperature effectExp2B take takes less time for moisture content to become zero that Exp2b air velocity effect

Theoretical moisture content curve

Moisture content in solid

•First falling rate period b) second falling rate period d) finish drying process

ERROR AND RECOMMENDATION

ERROR There is fluctuating of temperature of the hot air

blowing in. This can affect the process of drying because rate of evaporation inside the tray drier also will be fluctuating if the hot air temperature is not constant.

The water is sprayed on a certain concentrated portion of the sand making the evaporation of the water less and thus affecting the data recorded.

Some dirt and heavy dust particles may rest on the weight balance whose pan is placed at the top, and thus giving some error value to the weight of the tray.

RECOMMENDATION Average value should be taken to obtain

more accurate results. The values of temperature and relative humidity should be taken at least three times and get the average values.

The wet and dry bulb temperature sensor must be calibrated before experiment is done to obtain better readings.

The sand has to be sprayed evenly on the surface, and not the inner part of the sand.

CONCLUSION

Drying rate is directly proportional to the air temperature and the air velocity.

When the temperature increases, the drying rate is higher.

As the air velocity increase, the rate of drying is examined to be increase as well.

From this experiment, we can conclude that heat supply and air velocity are the two factors influencing the drying rate.

The objectives of the experiment are fulfilled.

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