3 - PROCESSING Flashcards
is an operation or set of action from a
specific sequence to the specific final end.
Processing
is the “action” that constitute a process, such as
cleaning, heating, cooling, and many others that produces a product.
Unit Operation
Portion of the material is separated from the entire material; Process condition such as temperature, pressure, etc usually
vary during the process;
BATCH PROCESSING
The material passes through the system continuously without
separation of a part of material from the bulk.
The condition at the start may vary but on the later part may
remain constant;
Continuous Processing
Composed of sequence of continuous and batch processes;
Usually starts with continuous then followed by batch process at
the middle and then followed by continuous process at the end;
MIXED PROCESSING
also called flow chart that shows the graphical
representation of various processes. It show the major operation of
a process in their sequence, the raw materials, the product and by
products.
FLOW DIAGRAM
This is a more detailed description of the process
that provides the information on the main pieces of equipment
selected to perform the operation. Standard symbols are used for
frequently utilized equipment such as pumps, blowers, conveyors,
vessels, etc.
BLOCK DIAGRAM
shows the pictorial of the equipment to be
used in the process. In here, secondary equipment and instrument are
reflected in the diagram.
Equipment Flow Diagram
deals with the principles and practices
of processing agricultural products suitable for food/feed. It
covers the activities after harvesting and process the food/feed for
safe storage for the next harvest. It is a primary processing
activity which does not alter the shape and form of the product.
Agricultural Processing
deals with the secondary processing of a
product after it undergoes primary processing. The original
shape and form of the product is altered making it more
attractive for human consumption.
Food Processing
crops that are produced and harvested with
normally low moisture content of about 20 to 30% and are not
easy to deteriorate or spoil.
Durable Crops
rops that have high moisture content (30%
and above) such as fruits and vegetables, including dairy, meat,
and fish and that easily deteriorate and spoil.
Perishable Crops
processing
operations which do not heavily
change the physical characteristics of
the product. Drying and dehydration
of grains and fruits are examples of
primary operation.
Primary Processing
processing
operations that change the physical
properties of the product. On-plant
processing such as converting
banana to catsup or mango to puree
are examples of secondary operation.
Secondary Processing
- Fluid at rest
- A study that deals with the fluid
at rest, such as those fluid
stored in tanks, etc.
Hydrostatic
- Fluid in motion
- A study that deals with the
various factors affecting the
relationship between the rate
of flow and the various
pressures tending to cause or
inhibit the flow.
Hydrodynamics
- They are compressible in nature and,
when compressed, some gases
change their state of matter. - Examples of these are air, flue gases,
biogas, etc.
Gases
- They are highly not compressible.
They can be compressed into a very
small degree only. - Examples of these are oil, milk, water,
etc.
Liquids
Mass in an isolated system is neither created nor destroyed by
chemical reaction or physical transformation. The mass of the
product in a chemical reaction must equal that of the reactant.
Conservation of Mass
The total energy of an isolated system remain constant – it is said
to be constant over time. Energy can neither be created nor
destroyed. It only transforms from one form to another
Conservation of Energy
Everybody continues in a state of rest or of uniform motion in a
straight line unless compelled by force to change that state.
The rate of change of momentum is proportional to the force
applied and takes place in the direction of the force application.
Newton’s Law of Motion
is
constant at any point in a system
and there is no accumulation or
depletion of fluid within the system.
rate of flow of fluid
Energy available because of
elevation above a reference
plane
Potential Energy
Energy available because of the
internal pressure
Pressure
Energy
Energy available from the
moving fluid
Kinetic Energy
is the sum of the three types of energy plus
the work supplied by a machine (pump) less friction of fluid in the
system (conduit and fittings, etc.).
Total hydraulic energy
factors affecting the flow of fluid (CSSCF)
- Characteristics of the fluid
- Size of pipe
- Shape of pipe
- Condition of the inside
surface of the pipe - Fluid velocity
– Fluid flows in parallel
elements.
– Direction of motion of each
element is parallel with the
other element.
Streamlined Flow
– Fluid moves in elemental
swirls or eddies.
– Both velocity and direction
of each element changes
with time.
Turbulent Flow
is an English investigator who first
demonstrated the finite existence of the
streamlined and turbulent flow.
Reynolds
is the internal resistance
of fluid to shear.
Viscosity
- Characterized by the rate of fluid
shear that is linearly related to
shear force. - Examples: oil, water, etc.
Newtonian Fluid
- The characteristics of fluid is not
linear with the shear force. - Examples: slurries, food purees,
paints, butter, mayonnaise, etc.
Non-Newtonian Fluid
It is the side of
pile in relation to the horizontal. It
varies with the moisture content and
with the amount of foreign matters
present.
Angle of Repose
This
determines the minimum pitch of
conduit intended to move the
materials by gravity.
Coefficient of Friction
- It is a pressure resulting from elevation and indicates forces
perpendicular to the walls of a container. - Pressure taken perpendicular from the direction of fluid.
Static Pressure
- It is a pressure that results from force due to change in
velocity of the fluid. - Pressure taken from the direction of fluid.
Dynamic Pressure
the simplest and most
reliable pressure gauge in which
pressures are determined by the
difference in height of the fluid inside
a tube.
Manometer
widely used for
operation control wherein accuracy of
approximately 2% is acceptable
Bourdon Tube
consists of spring-
loaded diaphragm or bellow which
actuates a series of levers attached
to the indicating hand
Diaphragm
- It is an open tube pointing into the
stream of fluid.
Pitot tube
- Preferable to the pitot tube
when average cross-sectional
velocity is desired. - Velocity indicated is a true
average. - Pressure
Venturi meter
- Based on the variation in resistance
of an electrical conductor with
conduit temperature.
Hot-wire anemometer
These are properties that lend themselves to
description and quantification by physical rather than chemical
means
Physical
The properties that determine the behavior of the
product when subjected to external forces.
Mechanical
This is relevant to agricultural and food process
engineering since almost all the products produce undergoes
different heat treatment from cooking to cooling and vice versa
Thermal
they are relevant to microwave and ohmic of the
material and to the effect of electrostatic force on the behavior of
powder.
Electrical
It affects the physical properties
of the product, particularly in terms of porosity, angle of repose, and
angle of friction. It is important in designing cleaning, and separating
equipment, as well as drying and storage facilities.
Surface Area
has an important role in drying and in storage of the
product. It indicates the relationship between the volume of the
product and the volume of the mass of the product. Porosity
depends on the shape, dimension, and roughness of the product
surface.
Porosity
is the ratio of the weight and the volume of the
product. It indicates how heavy the product is at a given volume. It
is normally expressed in kg/m3 of lb/ft3.
Bulk Density
is the angle at which the product forms a
conical shape from the horizontal after it is allowed to freely flow
from a discharge spout of the bin.
angle of repose
refers to the angle measured from the
horizontal at which a product starts to move downward over a
smooth surface and smoothness of the material
angle of friction
is the thermal property of material that indicates
the amount of heat transfer from one side of the material to the other
side by conduction.
Thermal conductivity
is the amount of heat required to
raise its temperature one degree higher when heat is added.
Specific Heat
is the amount of heat required to
remove certain amount of moisture from the product. In
estimating the amount of heat required to dry a product, the
information on the heat of vaporization is of much important.
heat of vaporization
is that property of grain
that holds moisture when it is subjected to a prolonged condition of
known temperature and relative humidity.
equilibrium moisture content
is the process of allowing the grains to rest in order for
the moisture at the innermost portion of the kernel to equilibrate
with the outer layer.
Tempering
Unhulled grain of Oryza
sativa
palay, paddy, rough rice
is one of the
most important indices in
determining whether the product
should be harvested already.
Moisture content
Moisture that can be found at the surface of the product,
particularly at the void spaces of the materials
free moisture
Moisture inside the tissue of the material which can be
removed by heating or reducing the vapor pressure within the
material.
bound moisture
Difficult-to-remove moisture and need chemical reaction by
high temperature or other means in order to remove it.
chemically-bound moisture
Factors affecting the choice of methods
- Form in which water is present
- Nature of the product analyzed (whether easily oxidized or
decomposed) - Relative amount of water present in the product
- Rapidity of determination
- Accuracy desired
- Cost of equipment required
This is commonly used by
researchers.
* The values obtained with this
method are used to calibrate all
secondary type of moisture
measuring devices.
* The steps are too cumbersome
and time consuming
primary method
- Much faster as compared
with the primary method. - Highly dependent on the
electrical properties of the
product.
secondary method
This
method requires a
sensitive analytical
balance and a
thermostatically-controlled
electrically-heated vacuum
Oven Method
This
method determines the moisture
by fractional distillation. The
sample is heated at a temperature
considerably above the boiling
point of water in 150 ml of mineral
oil. The vaporized moisture is
condensed and measured in a
graduated cylinder. The amount of
moisture collected is the
percentage moisture content of the
product, expressed in wet basis.
Distillation Method
In this
method, samples of known
weight is placed on top of a
platform scale of the meter
where it is heated at a
relatively high infrared
temperature.
Infrared Method
This method is based on the
principle that the electrical
resistance and conductivity of a
material depend upon the
moisture content
Electric Resistance Method
This
method determines the
moisture content of the
product due to its die-electric
properties. In this method,
the product is placed
between the two capacitor
plates of the meter and the
measured capacitance, which
varies with the moisture,
degree of compaction, and
temperature, is determined.
Dielectric Method
In this
method, water is removed
from the sample by the
addition of chemicals that
either decompose or
combine with the water.
Chemical Methods
– In this
method, the sample of the
product is placed in a sealed
container and allowed to
equilibrate with the air in the
container which has a known
relative humidity and
temperature.
Hygrometric Method
is the percentage amount of moisture as expressed
with the total weight of the sample. It is commonly used in
commercial expression of moisture content of the product.
Wet Basis
is the percentage amount of the moisture content as
expressed with the bone-dry weight of the product. It is a
commonly used expression of moisture in laboratory and/or
experiments
Dry Basis
A product has 25% moisture
content expressed in dry basis. What
is the percentage moisture content of
the product in wet basis?
20%
f a product has 12% moisture
content expressed in wet basis, the
equivalent percentage moisture
content in dry basis is
13.6%
If 20 kg of water is to be
removed from 110kg paddy, what is
the percentage moisture content of
the paddy in wet basis?
18.18%
What is the percentage moisture
content of the paddy in Item 18 when
expressed in dry basis?
22.2%
Determine the amount of moisture
that can be removed from 9 tons of
paddy with 24% initial moisture
content dried to 14%.
1.05 tons
What is the amount of moisture to
be removed from a material with
14.5% moisture content and 76 kg dry
matter weight?
12.89 kg
What is the percentage
moisture content of paddy in Item
21 when expressed in dry basis?
16.95%
the study of the properties of the air, and use of the
psychrometric chart are essential for an understanding of
the processes involved in drying and storage of grains and
other agricultural crops, and in analyzing individual
requirements for a particular climatic condition.
psychrometry
is a device that simplifies the
measurement of air properties and eliminates many timeconsuming and tedious calculations that would otherwise be
necessary.
psychometric chart
is simply a graphic
presentation of the conditions or properties of air, such as
temperature, humidity, and dewpoint.
psychometric chart
Is the temperature of the air
as measured using an
ordinary thermometer, such
as a household thermometer.
Dry-Bulb Temperature
As
the temperature of the bulb
increases, the liquid in the
bulb ____ and ____ in the
stem.
expands and rises
Is the temperature of the air as
measured using an ordinary
thermometer in which the
glass bulb is covered with a
wet cloth or gauze. The clean
cotton wick absorbs water
Wet-Bulb Temperature
Is the temperature at which
moisture condenses on the
surface. It is the
temperature at which
condensation occurs when
air is cooled at constant
humidity ratio and constant
atmospheric pressure.
Dewpoint Temperature
Is the ratio of the partial
pressure of water vapor in
the atmosphere to the
pressure that saturated
water vapor exerts at the
temperature of the air.
Relative Humidity
Is the weight of the water vapor
contained in the moist air per
unit weight of dry air. Other
terms used for humidity ratio
are absolute humidity and
specific humidity.
Humidity Ratio
The enthalpy of a dry-air-watervapor mixture is the heat
content of the moist air per unit
weight of dry air above a certain
reference temperature.
Enthalpy
is defined as the
volume per unit weight of
dry air.
specific volume
Is the unit of measurement
used to determine the
amount of moisture in the air
Grains of Moisture
If the dry-bulb and wet-bulb temperatures are known, the
_____wet-bulb temperature can be read from the chart
relative humidity
If the dry-bulb temperature and the relative humidity are known,
the _____ can be determined.
wet-bulb temperature
If the wet-bulb temperature and the relative humidity are known,
the ____can be found.
dry-bulb temperature
f the wet-bulb and dry-bulb temperatures are known, the
______ can be read from the chart.
dewpoint
If the dry-bulb temperature and the relative humidity are known,
the _____ can be found.
dewpoint
are used in agricultural processing in connection
with drying, ventilating, heating, cooling, refrigerating, aspirating,
elevating, and conveying.
Fans and blowers
Operate at pressures equal to or more than 1 lb/in2 (27.7 in. ofwater). Machines in this class also include centrifugal
compressors and turbo compressors.
Blower
Operate at pressures of less than 1 lb/in2 (27.7 in. of water).
Machines in this class are also called centrifugal fans, fans
blowers, or exhausters.
fans
