Problem C1: Spray Drying

Katipunan, Hazel E.Lizardo, Syreanne C.

Maniego, Carlo P.Revalo, Orly M.

5ChE-A

•Objectives

To calculate the heat effects involved in the operation of a spray dryer

To determine the efficiency of the spray dryer used in terms of percentage recovery of the dried solids.

Spray Dryer with Atomizer 220 V

Air Compressor

Anemometer

Cotton

Detergent

•Equipment / Materials

Stirring Rod

Collecting Jar

500-mL beaker

Distilled Water

Timer

•Equipment / Materials

•TheorySpray Dryer

•TheorySpray Dryer• Liquid feed is pumped into a spray-disk atomizer.

•Droplets are formed inside cylindrical drying chamber.

• Cooled gas is drawn by an exhaust fan through a horizontal discharge line set in the side of chamber.

•TheorySpray Dryer• Exhaust air passes through cyclone separator.•Dry solids settles out of the gas into the bottom of the chamber.

•TheoryAdvantages of Spray Dryer:

• Very short drying time

• Production of hollow spherical particles

•Desired consistency, bulk density, appearance, and flow properties of products may obtained easily compared to other dryers

•Theory

• Yielding from a slurry, in a single step, dry product is ready for package

•May combine the functions of evaporator, classifier, dryer, crystallizer, or size reduction unit.

•TheoryDisadvantages of Spray Dryer:• It is bulky and large equipment.

• It is not always easy to operate.

• Bulk density of dry solid is often difficult to kept constant.

•Theory

Wet Bulb Temperature

• Is the steady-state, non- equilibrium temperature reached by a small mass of liquid exposed under adiabatic conditions to a continuous stream of gas

•TheoryMethod of measuring the wet bulb temperature:

• A thermometer or other temperature-measuring device is covered by a wet wick, which is saturated with pure liquid and immersed in a stream of gas having definite temperature and humidity.

•Methodology/Operating ProcedurePrestart-up Guidelines• Liquid distributor be correctly mounted noting the wheel be rotating freely

• Air must be made sure that its not sucked into the dryer system due to air leakage

• Initial weight of the collection jar be noted and fastened securely

•Methodology/Operating Procedure• Compressed air 5 – 6 kg /cm2 (70 – 90 lbs/in2) supplied

• Air hose attached to the stud located at the back of the instrument panel

•Oil or water separator must be placed I the compressed air line

•Methodology/Operating Procedure

• Prepare slurry containing 30% by mass detergent

•Weight of dry solids and weight and slurry before drying

•Methodology/Operating ProcedureStartup•Open the spray dryer unit by turning on the power

•Operation switch from 0 to M to start the fan

• Switch turned to either I, II or III depending on inlet air temperature required. Use % timer to desired air temperature

•Methodology/Operating Procedure•With the heater on and the fan started, the atomizer be started by completely opening the air valve

•Distilled water be passed to the atomizer until required outlet air temperature obtained

• Switch to feed slurry after obtaining desired temperature

•Methodology/Operating Procedure

Main Experiment

• Feed the slurry and air temperature at a constant rate together

•Methodology/Operating ProcedureFollowing Experimental data be gathered

• Inlet air temperature, Ti•Outlet Air Temperature, Tc•Operating Pressure of Atomizer•Absolute Humidity of air at Ti•Absolute humidity of air at To• Inlet Temperature of solids, T’•Air Velocity• Total Run Time

•Methodology/Operating Procedure

• Replace the Collecting jar after approximately ten minutes after the contents runs out

• Repeat the process for another feed rate by varying the opening of feed container

•Methodology/Operating ProcedureShut Down

• Switch to distilled water noting and regulating the amount of water fed

• Run the unit for another 5- 10 minutes

• Switch off the heater, set the % timer to zero, and operation switch at M

•Methodology/Operating Procedure

• Turn off the water supply and turn off atomizer 3 minutes later

• Introduce cold air through the dryer for 5 minutes

• After the retained powder have been swept when air temp is 50°C, turn off operation to zero

•Preparation of Detergent Slurry

100250

30

x

x

THANK YOU!!