University of San CarlosDepartment of Chemical Engineering

CHE 512L Chemical Engineering Laboratory 2

Experiment Plan(Form CHE512L-1)

Prepared and submitted by:

Ynno C. Igut Javen Anne B. Magadia Franz Loui E. Rosario

Experiment : EvaporationObjectives of the Experiment

1. Investigate the effect of the feed rate on the evaporator product concentration.2. Investigate the effect of the operating steam pressure on the rate of evaporation.3. Determine the overall heat transfer coefficient of the calandria and compare with values predicted

from empirical correlations.4. Perform steady-state mass balance over the evaporator system to estimate mass losses during the

evaporation operations conducted.

Methodological Framework

Objective 1

1

Product Concentration

convertConcentrate Flowrate

effect onVarying Feed Flowrate

(at constant steam pressure)

Objective 2

Objective 3

3.1 Empirical heat transfer coefficient

Basis:

q=U emp A (T s−T b) [1]

where:

q = latent heat of condensation Uemp = empirical overall heat transfer coefficient A = surface area of calandria Ts = steam temperature Tb = temperature of boiling liquid

Framework:

Obtain Uemp by obtaining data on the feed boiling temperature with the given steam temperature.

3.2 Theoretical heat transfer coefficient

Basis:

U theo=1

1hi

+1ho

[2]

where:

2

Amount of Condensate per unit time

(Rate of evaporation)

effect onVarying Steam Pressure

(at constant feed flowrate)

Utheo = theoretical overall heat transfer coefficient hi = feed side film coefficient ho = steam side heat transfer coefficient

Framework:

Obtain hi and ho using Seider-Tate correlation; Obtain Utheo

Objective 4

Materials, Measuring Apparatus & Equipment

Material QuantitySucrose 1 kgDistilled water 15 L

Apparatus Size QuantityImmersion heater - 1Densitometer - 1Weighing scale - 1Plastic beakers 5 L 2Graduated cylinders 100 mL, 2 L 2Thermometer - 1

Equipment SpecificationsClimbing film evaporator

- Calandria Tube 25 mm ID, 3 m long- Steam Jacket 50 mm ID, 2.7 m long- Concentrate receiver 7-L capacity- Condenser Cooling water at ~27 °C- Product Receiving Vessels 5-L capacity- Vacuum Pump 26 in Hg, powered by 1/3 hp

3

Do mass balanceObtain mass flows of inlet and outlet streams

Task Plan

Time Task Person Responsible

9:00-10:00 Familiarization of equipment AllQuestioningPreparation of the Feed

10:00-10:30Add 1 kg of sugar to 15 L of distilled water in a bucket MagadiaHeat the solution to 60 °C using an immersion heater RosarioDetermine the density of the solution using a densitometer Magadia

Start-Up Operation

10:00-10:30

Close all drain valves, air vents, and the recycle valve of the set up

IgutOpen the vacuum cocks and the valve connecting the twin receiversAllow soft water to flow through the pipeline Open the by-pass valve located after the steam pressure gaugeFit a hose to the feed inlet with the other end dipped in the calibrated vessel containing the sugar solution Rosario

Experiment Proper

10:30-11:30

Switch the vacuum pump on and adjust to give a reading of 20 in Hg on the vacuum pressure gauge Rosario

Open carefully the main steam supply valve. As the steam surges, slowly open the steam supply valve and adjust the regulating valve register 5 psig on the regulated steam pressure gauge. Allow condensed steam to be flushed out of the calandria and close the by-pass valve.

Igut

Open the cock controlling the vent at the top of the calandria to release any non-condensable gases that may be present Rosario

Open the feed inlet valve and control the feed flow rate so that the liquid level in the calandria is just above the steam inlet neck. Magadia

Adjust the feed rate so as to maintain the liquid level corresponding to a marked height at the outer surface of the steam jacket. Allow five minutes for the system to equilibrate and then measure the height of the liquid from the base of the calandria or use a graduated cylinder and stopwatch.

Rosario

Once the concentrate level reaches the zero mark, simultaneously close the valve between the two condensate receivers and catch the condensed steam from the discharge line into a plastic container for test period of 15 minutes.

Igut

Close the vacuum vent of the lower condensate receiver, open its air vent, and drain the condensed vapor into a beaker. Rosario

Restore the receiver to its original setting before opening the valve connecting it to the upper condensate receiver. Igut

At the end of the 15-minunte period, simultaneously close the valve between the twin condensate receivers, read the level of the concentrate and stop the collection of the condensed steam

Magadia

Determine the temperature, volume, and density of the condensate, concentrate, condensed steam collected All

4

12:00-1:00 Repeat the experiment using a higher feed rate All

1:00-2:00 Perform another set of the same experiment at a higher operatig steam pressure of 10 psig All

Shutdown

2:00-3:00

Close the feed and the steam-regulating valves while operating the by-pass valve. Close the evaporator steam inlet valve and the main supply valve. Turn off the vacuum pump.

Igut

Close the condenser cooling water inlet valve. Close the vacuum cocks on the condensate receivers, and open the air vents. Rosario

Drain out the feed, the concentrate, and the condensate remaining in the setup Magadia

5

6

Information Flow Diagram

7

8

9

10

Legend

Raw Data Sheets

Table 1. Feed preparationMass of sugar (kg) Mass of distilled water

(kg)Temperature (°C) Buoyancy (g)

Table 2. Data collected for Trial 1

TRIAL 1 Volume collected T (°C) Buoyancy (g)Vi (L) Vf (L)

FeedConcentrateCondensateCondensed Steam

Table 3. Data collected for Trial 2

TRIAL 2 Volume collected T (°C) Buoyancy (g)Vi (L) Vf (L)

FeedConcentrateCondensateCondensed Steam

Table 4. Data collected for Trial 3

TRIAL 3 Volume collected T (°C) Buoyancy (g)Vi (L) Vf (L)

FeedConcentrateCondensateCondensed Steam

Table 5. Height of the solution in calandria and vapor temperature for the three trials

Trial Height of sol’n in calandria

(cm) Vapor Temperature

Initial (°C) Final (°C)

123

11

12