1. Submitted to:
Dr. Arockiya Aarthi Rajathi,
Department of Microbiology.
Assistant professor,
Submitted by:
P.Pugazhenthi,
I-Msc, Microbiology.

2. Steam heated drum drying &
Cross flow air drying

3. STEAM HEATED DRUM DRYING
 Initially the boilers were designed with 4 drums or
3 drums like stirting boiler.
 The single drum at bottom and three drums on the
top were connected through a network of tubes.
 The rational demand of stream in terms of
capacity, pressure and temperature.

4. STRUCTURE:

5. FUNCTION:
 Within the boiler, fuel and air are force into the
furnace by the burner.
 There, it burns to produce heat.
 From there, the heat (flue gases) travel
throughout the boiler.
 The water absorbs the heat, and eventually
absorb enough to change into a gaseous state -
steam.
 To the left is the basic theoretical design of a
modern boiler.
 Boiler makers have developed various designs to
squeeze the most energy out of fuel and to
maximized its transfer to the water.

6.  Water enters the boiler, preheated, at the top.
 The hot water naturally circulates through the
tubes down to the lower area where it is hot.
 The water heats up and flows back to the steam
drum where the steam collects.
 Not all the water gets turn to steam, so the process
starts again.
 Water keeps on circulating until it becomes steam.
 Meanwhile, the control system is taking the
temperature of the steam drum, along with
numerous other readings, to determine if it should
keep the burner burning, or shut it down.

7.  As well, sensors control the amount of water entering
the boiler, this water is know as feedwater.
 Feedwater is not your regular drinking water.
 It is treated with chemicals to neutralize various
minerals in the water, which untreated, would cling to
the tubes clogging or worst, rusting them.
 This would make the boiler expensive to operate
because it would not be very efficient.
 On the fire side of the boiler, carbon deposit resulting
from improper combustion or impurities in the fuel can
accumulate on the outer surface of the water tube.
 This creates an insulation which quickly decrease the
energy transfer from the heat to the water.

8.  This device, which looks like a lance, has a tip at the
end which “blows” steam.
 This blowing action of the steam “scrubs” the outside
of the water tubes, cleaning the carbon build up.
 Water tube boilers can have pressures from 7 bar to
as high as 250 bar.
 The steam temperature’s can vary between saturated
steam, 100 degrees Celsius steam with particle of
water, or be as high as 600 - 650 degrees Celsius,
know as superheated steam or dry steam.
 The performance of boiler is generally referred to as
tons of steam produced in one hour.
 In water tube boilers that could be as low as 1.5 t/hr
to as high as 2500 t/hr.

9. CROSS FLOW AIR DRYING
 One of the most popular continuous flow dryers
called cross flow dryers.
 In this type of dryer the air glow is generally
perpendicular to the grain flow.
 The cross flow dryers combine the simple
operation of a batch system with the increased
efficiency of a semi continuous design.
 In this type of dryers, the blower forces hot air
through many small ducts or channel.
 This reduces drying time and allows processing of
all the trays at once.

10.  To prevent the over heating of the trays a cross
flow dryer uses sensors to control the blower
output.
 The wet solids of spirulina containing 55-66%
moisture after the cloth filtration were dried at 62
degree celsious for 14 hrs.
 When sun drying is not possible due to cloudy
or rainy wheather.
 The process is cheaper than drum drying.

11. STRUCTURE

12.  Reference:
 Text book: Biotechnology & utilization of algae the
Indian experience- L.W. Venkata Raman, E.N.Becker.
 https://scholar.google.co.in