theorie part 2 air treatment
Post on 03-Apr-2018
245 Views
Preview:
TRANSCRIPT
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 1/239
Air Treatment
Capt. K. De Baere
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 2/239
Introduction
Air quality in the cargo holds is important,damage that can be caused by inadequate
ventilation; Damage to the cargo
Overheating of the cargo
Depreciation of the cargo
Rotting of the cargo Contamination by odour
Accumulation of inflammable, toxic and noxious gasses
Spontaneous combustion of the cargo
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 3/239
Introduction
Damage to the ship
Sweating of ship and cargo
Staining of the holds
Oxidation of the ships structure
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 4/239
Purpose Ventilation and
Conditioning Controlling humidity – Absorption and
condensation as a consequence of temperature
variations Controlling dust during cargo operations
Controlling oxygen
Evacuation of;
Contaminating vapours
Exhaust gas on board of Ro-Ro’s
Explosive cargo gas by means of IG on board of tankers
Toxic gas
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 5/239
Purpose Ventilation and
Conditioning Managing temperature
Managing chemical composition of the hold
atmosphere
IG on board of tankers
Ripening (maturing) process on board of fruit
carriers (N2, CO2 en ethylene)
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 6/239
Ventilation
Natural ventilation
Mechanical ventilation
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 7/239
Natural Ventilation
Use the natural circulation of air
Wind
Natural movements of the air f.i. warm air rises
and cold air comes down (convection)
This natural ventilation is realized by;
Ventilation ducts
Opening and/or closing of hatch covers
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 8/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 9/239
Ventilators – not mechanical
Provision of an
eductor improves the
evacuation of air (Venturi principle)
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 10/239
Ventilation cowls
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 11/239
Ventilators – not mechanical
Inside the ventilator coaming a metal cross is provided to prevent the passage of thieves or
stowaways The ventilator cowl is closed by a grid
Fire screen
To prevent the passage of unwanted objects
In case of very bad weather the air ducts (cowls)on deck can be removed and the openings areclosed by means of a metal lid
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 12/239
In case of bad
weather theventilation
cowls are
turned and
covered
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 13/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 14/239
Ventilators – not mechanical
In case of bad weather the ventilator cowls
are swivelled in the opposite direction of the
wind and covered with canvas
Samson posts are often used as ventilator
ducts and are provided with mushroom
shaped caps
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 15/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 16/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 17/239
Ventilation caps
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 18/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 19/239
First ‘assisted’ ventilation – wind
sails with 2 or 4 sails
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 20/239
Problems related to natural
ventilation Insufficient capacity
Incorrect positioning of the air ducts
Corners of the hold are insufficiently ventilated
Positioned so that they are exposed to the weather
conditions, green water and seas on deck => they have
to remain closed => insufficient ventilation
Insufficient number of ducts on each side of the
hold (ventilation is interrupted by a temporary
separation in the hold f.i. by the cargo)
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 21/239
Problems related to natural
ventilation
Hot and damp air escaping from the cargo is captured
between the deck stringers => condensation
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 22/239
Problems related to natural
ventilation
Ventilation is improved by providing ventilation
holes in frames, deck stringers and brackets
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 23/239
Problems related to natural
ventilation
If the ventilation tunnels are not going deep enough only a
surface ventilation is provided This is OK for coal or other bulk cargoes but not for
general cargo
Sometimes special constructions are provided to allowadequate ventilation inside the cargo
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 24/239
Inside ventilation
Rice and Soya beans
These products release alot of humidity and CO2
during transport => must be evacuated
Tank top is covered withdunnage and separation
cloth 1 layer of bags is spread
out
On top of these bags theventilation ducts are
installed
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 25/239
Inside ventilation
On the intersection
between the longitudinal
and transversal duct a
vertical duct is constructed
After 3 to 5 layers of bags
the whole constructing is
repeated
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 26/239
Problems related to natural
ventilation This can be solved when the
inlet ducts are extended till the
bottom of the compartment The cold air on the bottom will
rise to the top of the hold
Outlet ducts to be provided ator near the top of the cargohold
The inlet ducts are providedwith flaps allowing surfaceventilation
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 27/239
Natural ventilation is regulated
by trimming the cowls
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 28/239
Natural ventilation
A lot of hot damp air can be evacuated when the hatchesare opened and all of the cowls are turned towards thewind
This is very effective in cold regions
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 29/239
Natural ventilation – smoother
method
All cowls are turned away from the wind => the
hot air is sucked out (warm air rises)
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 30/239
Mechanical ventilation
The only difference with natural ventilationis that mechanical ventilators – fans – are
used Fans are reversible
Operation is electrical
Fans are operated from the bridge or E.R. The ventilation ducts can be opened or
closed on each level by means of flaps
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 31/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 32/239
Mechanical ventilation on board
of a PCC = Pure Car Carrier
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 33/239
Mechanical ventilation
Capacity of the ventilation system is
expressed by the number of air changes per
hour
On board of a car carrier the capacity during
sea voyage must be 10 changes per hour
this will be increased till at least 20changes per hour during loading and
discharging operations
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 34/239
Distribution of ventilators on
board of a ro-ro ship
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 35/239
Air conditioning
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 36/239
Psychometrics
Study of the thermodynamics and the
humidity of air
Important on deciding if an air treatment
method is appropriate
Psychometrics or hygrometry is the study of
how the properties of moist air can changeas a result of air conditioning processes.
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 37/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 38/239
Psychrometer
By means of a psychrometer we canmeasure the hygrometric state of the air
A psychrometer consists out of a wet and adry bulb
Because of the evaporation the wet bulb
will indicate a lower temperature Relative humidity can be determined by
means of special tables
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 39/239
Humidity
Humidity is the amount of water vapour in
the air and can be described in different
ways.
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 40/239
Absolute humidity [gr/m3]
1. The ratio of the mass of water vapour to
the volume occupied by a mixture of
water vapour and dry air.
2. Mass of water contained in a unit volume
of moist air.
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 41/239
Actual vapour pressure
The partial pressure exerted by the water
vapour present in a parcel. Water in a
gaseous state (i.e. water vapour) exerts a pressure just like the atmospheric air.
Vapour pressure is also measured in
millibar .
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 42/239
Saturation of air
The condition under which the amount
of water vapour in the air is the
maximum possible at the existingtemperature and pressure.
Condensation or sublimation will begin if
the temperature falls or water vapour isadded to the air.
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 43/239
Table van Regnault – saturation
vapour pressureTemp [°C] Press [mb]
0 6.1
5 8.7
10 12.3
15 17.1
20 23.3
25 31.7
30 42.4
35 56.3
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 44/239
Table Regnault
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 45/239
Dew point
The temperature air would have to be
cooled to in order for saturation to occur.
The dew point temperature assumes there isno change in air pressure or moisture
content of the air.
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 46/239
Relative humidity
The amount of water vapour actually in the
air divided by the amount of water vapour
the air can hold. Relative humidity isexpressed as a percentage and can be
computed in a variety of ways. One way is
to divide the actual vapour pressure by thesaturation vapour pressure and then
multiply by 100 to convert to a percent
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 47/239
Dry bulb temperature
The dry-bulb temperature of air is measured
by a thermometer which is freely exposed to
the air but is shielded from radiation andmoisture
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 48/239
Wet bulb temperature
The Wet-bulb Temperature of air is
measured by a thermometer whose bulb is
covered by a muslin sleeve which is keptmoist with distilled and clean water, freely
exposed to the air and free from radiation
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 49/239
Sling psychrometer - animated
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 50/239
Sling psychrometer
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 51/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 52/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 53/239
Psychometric charts
The psychometric chart is a useful design tool for
ventilation purposes. The chart presents a number
of properties of moist air: dry-bulb temperature
sling wet-bulb temperature
moisture content
specific enthalpy
specific volume
percentage saturation
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 54/239
Psychometric charts
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 55/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 56/239
Psychometric chart
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 57/239
Psychometric charts simplified
At first glance, even a simple psychometric
chart appears complex. However, separating
the various lines and scales on the chartsimplifies understanding their location,
meaning and use.
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 58/239
Dry bulb temperature
The dry bulb
temperature scale is
located at the base of the chart. Vertical
lines indicate
constant dry bulb
temperature
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 59/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 60/239
Dew point temperature
Dew point temperature is the
temperature below which moisture
will condense out of air.(saturated)
The dew point temperature scale is
located along the same curved
portion of the chart as the wet bulb
temperature scale. However,
horizontal lines indicate equal dew point temperatures
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 61/239
Relative humidity
Lines representing conditions of
equal relative humidity sweep from
the lower left to the upper right of
the psychometric chart. The 100 %relative humidity (saturation) line
corresponds to the wet bulb and the
dew point temperature scale line.
The line for zero percent relativehumidity falls along the dry bulb
temperature scale line.
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 62/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 63/239
Example 2 – image is not correct
The air in a cargo hold
has a dry bulb
temperature of 80° F andis at 70 percent relative
humidity. How warm do
the bulkheads have to be
to prevent condensation?
The dew point temperature is 69°F. The bulkhead temperature must
be warmer than this to prevent condensation.
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 64/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 65/239
Consequences of an excessive
humidity Ship’s sweat
Cargo sweat
Foodstuff becoming mouldy
Fungus
Rust and oxidation of the ship’s structural
elements
Rotting wood
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 66/239
Practical Ventilation On Board
If the relative humidity is < 30% non of the abovementioned problems will arise.
Natural ventilation wants to replace the air in theholds with dryer air (< relative humidity)
In case of low outside temperature the relativewarm hold air will condense in the exhaust
ventilation shafts => humidity runs back into thehold => damage. This is especially the case whenhigh exhaust air shafts are used f.i. Samson posts.
Sometimes ventilation has to be stopped at night
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 67/239
Practical Ventilation On Board
Suppose air temperature – dry bulb – 19°
Vapour tension is 14mb (absolute humidity)
At 19°C saturation vapour tension is 22mb(see Regnault – next slide)
Relative humidity is 14/22x100% = 63.6%
At 12°C saturation vapour tension is 14mb => the temperature has to drop to 12°C
before condensation will occur
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 68/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 69/239
Practical Ventilation On Board
Air will condensate on every surface with a
temperature < or = 12°C
A ship loaded with agricultural products (highhumidity) going to colder regions => a lot of
condensation on the ship skin (will take over
lower outside air- and sea temperatures quickly)
Solution: replace the hold atmosphere with dryer
air (air with a lower dew point)
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 70/239
Practical Ventilation On Board
Cargo sweat
Cargo products that have been stored ashore inrefrigerated spaces
On board of ships going warmer regions
Cargo will take over the outside temperature slower that the ships structure
Condensation of the warm air on the colder cargo
surfaces = Cargo sweat Especially important on steel products, tins, cardboard
boxes etc.
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 71/239
Practical Ventilation On Board
Heat or cold, generated on board, can also bring aboutcargo- or ship sweat
Poorly isolated boiler rooms or engine rooms radiate heat
=> condensation on colder ship or cargo surfaces Bulkheads in the neighbourhood of cooled or refrigerated
spaces => condensation of the warmer surroundingatmosphere
The air that comes in contact with these colder surfaceswill cool down=> higher relative humidity =>condensation & absorption by hygroscopic products
l i
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 72/239
Montreal -> Vancouver via
Panama
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 73/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 74/239
When ventilating?
Dew point of the outside air < dew point of
the hold air => atmosphere of the hold will
become dryer Temperature of ships structure and cargo
must be > dew point of the air if not cargo-
or ship sweat will occur.
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 75/239
Drying of air
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 76/239
Drying of air
Drying of air means – extract the water
1. By cooling the air. Humidity will condensate
and can be evacuated. Air is heated againafterwards
2. By using hygroscopic substances absorbing
the humidity
Th
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 77/239
Cooling of air 1. The compressor compresses
cool Freon gas, causing it tobecome hot, high-pressure
Freon gas (red in the diagramabove).
2. This hot gas runs through a setof coils so it can dissipate itsheat, and it condenses into a
liquid.
3. The Freon liquid runs throughan expansion valve, and in theprocess it evaporates tobecome cold, low-pressureFreon gas (light blue in thediagram above).
4. This cold gas runs through a setof coils that allow the gas toabsorb heat and cool down theair inside the building.
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 78/239
Mechanical drying systems
Composing elements
Closed circuit with containing a cooling medium(freon)
Compressor
Condenser – liquefies the freon
Liquefied freon is collected in a pressure vessel
The cooling medium is released by means of an
expansion valve The medium is passed trough an evaporator (heat
exchanger)
The air is cooled => condensation
P h t i h t h i th
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 79/239
Psychometric chart showing the
drying process1. Start of the cooling
process
2. Saturation (dew point) is reached
3. Temperature dropsand humiditycondensates.Humidity ratio hasdropped from 80% to 45%
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 80/239
Drying IG on board of a tanker
1. Compressing and cooling of IG
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 81/239
Drying IG on board of a tanker
2. Drying of the IG with PSA (Pressure Swing
Absorbtion)
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 82/239
PSA - systeem
D i t i
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 83/239
Drying systems using
hygroscopic substances
2 principles are used
Absorption -> the product changes fysically
and chemically on absorbing moisture Lithium chloride
Triethylene glycol
Adsorption -> no chemical or physical change
takes place after the adsorption of humidity
Sillicagel
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 84/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 85/239
Drier with absorbing liquid
Consists out of 2 chambers
and a pumping unit
1. Dehumidification chamber
(contact with absorbing liquid – litthium chloride – in the left
part and filter in the right part)
2. Regeneration chamber –
regeneration of the absorbingliquid
Drier ith do ble adsorbing in a
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 86/239
Drier with double adsorbing in a
drying tower
2 towers each filled
with sillicagel
1 in use, the other being regenerated with
warm, dry air.
PSA – Pressure Swing
Absorption
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 87/239
Drier with rotating adsorbing bed
The beds containing thesillicagel are constantly turning
The drying part and
regeneration part are onlydivided by a flexible bulkhead
Drying and regeneration take place at the same time
The regeneration air is dried atthe inlet while the dried air iscooled (transformation of vapour in water dropletsgenerates heat) at the outlet
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 88/239
Installation using sillicate rotors
Hygroscpic installation on board
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 89/239
Hygroscpic installation on board
of a chemical tanker
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 90/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 91/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 92/239
Honeycomb driers
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 93/239
Honeycomb
technology
Industrial installation
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 94/239
Industrial installation –
Honeycomb technology
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 95/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 96/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 97/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 98/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 99/239
Recirculation
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 100/239
Instruments
Dewpointaire console – compares dry and
wet bulb temperatures of outside air and the
hold atmosphere Cargo sweat and hold sweat can be avoided
by analysing these values
Dew point of the hold can be influenced byventilation, drying or cooling
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 101/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 102/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 103/239
Cooling of cargo holds
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 104/239
History
In 1876, the French
engineer Charles
Tellier transported a
meat shipment from
Buenos Aires to
Rouen. aboard his own
steamer « leFrigorifique ».
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 105/239
Evolution in cooled transport
The primary refrigerated products are
bananas, meat, citrus fruit, fish and seasonal
fruit. Developments over the last 15 yearswith regard to these various refrigerated
goods can be seen from the following
tables. The highest growth in absolute terms
is in bananas and meat, which have a large
share of the overall market anyway.
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 106/239
Evolution in cooled transport
Proportions of the different
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 107/239
Proportions of the different
refrigerated transported by sea
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 108/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 109/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 110/239
h l d ?
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 111/239
Why cooled transport?
Ever increasing distance between producer andconsumer
Necessary for consumables to arrive in optimal
condition
The cold slows down the ripening process of fruitsand vegetables
The cold avoid meat and fish to be destructed bygerms
Certain chemical reactions are inhibited
The cold extends the conservation time of
consumables
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 112/239
Preservation of refrigerated
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 113/239
Preservation of refrigerated
commodities
Temperature control
Level of CO2 in the stowage compartment
Ripening fruit produces ethylene and CO2
Ethylene and CO2 must be removed to minimise theripening process
Excess humidity will cause moisture deposits onthe cargo space structure => development of
micro-organisms
To dry atmosphere will lead to moisture loss =>freezer burn
F B
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 114/239
Freezer Burn
Freezer burn(deshydration) istypified by a loss of
moisture that affects both texture andflavor. Freezer burn isindicated by a dry
surface, which mayalso have white or gray spots on it.
Freezer burn on ox-tongue
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 115/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 116/239
R f i t d
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 117/239
Refrigerated cargoes
Frozen
- 12°C => - 25°C
Exact temperature is not so important as long as it is
below the freezing temperature of the product
Chilled
- 2°C => + 13°C
Technique is much more delicate. Each product must be
transported at an exact temperature and in a controlledatmosphere.
Air-cooled
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 118/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 119/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 120/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 121/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 122/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 123/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 124/239
Frozen meat in boxes
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 125/239
Frozen meat in boxes
Transport of fish
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 126/239
Transport of fish
Chilled or frozen
Conservation time between 15 days (0.5 à
2°C) and 4 months (-18°C) Fish is transported in carton boxes or crates
Transport of fruit and vegetables
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 127/239
Transport of fruit and vegetables
Fruits and vegetables are harvested atmaximum size before maturation
Fruit and vegetables are living organisms,they absorb O2 and release CO2, heat andwater vapour
2 categories are distinguished
Without amylum (zetmeel)
With amylum (zetmeel)
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 128/239
Chilled
products
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 129/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 130/239
Cargo
compatibility
refrigerated
products
O = yes N = No
R = Risk
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 131/239
Cargo
compatibility
frozen
products
O = yes N = No
R = Risk
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 132/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 133/239
Bananas
Musa familie = bananas
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 134/239
Musa familie = bananas
Musa family is very large
2 major edible varieties
Banana (Musa Paradisiaca AAA) – fruit eatenuncooked
Plantain (Musa Paradisiaca ABB) – must be
cooked before consumption
Banana
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 135/239
Banana
Plantain
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 136/239
Plantain
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 137/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 138/239
Banana Plant
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 139/239
Banana Plant
Banana plants are the largest plants on earth without awoody stem. They are actually giant herbs of the samefamily as lilies, orchids and palms.
Today's commercial bananas are scientifically classifiedinto the genus Musa of the Musaceae family.
The Cavendish is the most common variety of bananasnow imported to the United States. The Cavendish is ashorter, stubbier plant than earlier varieties. It was
developed to resist plant diseases, insects andwindstorms better than its predecessors. The Cavendishfruit is of medium size, has a creamier, smooth texture,and a thinner peel than earlier varieties.
Banana Plant
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 140/239
Banana Plant
Bananas are perennial (vorstbestendige overblijvende)crops that are grown and harvested year-round. Thebanana plant does not grow from a seed but rather from arhizome or bulb. Each fleshy bulb will sprout new shoots
year after year.
Each banana plant bears only one stem of fruit. Toproduce a new stem, only two shoots - known as thedaughter and the granddaughter - are allowed to grow and
be cultivated from the main plant. The banana plant reaches its full height of 15 to 30 feet in
about one year.
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 141/239
Banana Plant
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 142/239
Banana Plant
After the stem forms on the plant, it is covered with alarge, transparent plastic bag which shields it frominsects, birds and leaf damage, yet allows the sun toreach the fruit.
On each stem, ten or more bananas growing together are called "hands" and a single banana is called a"finger." Four to six bananas sold in the retail storeare called a "cluster.“
Banana plants require intensive, individual care:clearing away of jungle growth, propping to counter bending from the weight of the growing fruit, andirrigation during the dry season.
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 143/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 144/239
Banana Flower
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 145/239
Banana Flower
Bananas ready to be harvested
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 146/239
approx. 100 days after flowering
Bunches after harvesting
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 147/239
Bunches after harvesting
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 148/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 149/239
Sorting
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 150/239
Sorting
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 151/239
Boxing
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 152/239
Boxing
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 153/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 154/239
A hand of bananas
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 155/239
A stem consists out of
a number of hands
(from a few to > 10)
A freshly cut hand of
bananas.
A hand consists out of
10 to 20 bananas, alsocalled fingers
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 156/239
Transport of bananas
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 157/239
Modern reefers – anno 2004
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 158/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 159/239
Basic principles
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 160/239
p p
The degree of ripeness when the banana was cut.
The pre-critical phase of « lean » fruit is better
than the pre-critical phase of « full » fruit
Temperature: The pre-critical phase takes 15 to 18
days at 12°C and only a few days at a temperature
slightly higher
Humidity: When the humidity is to high therespiration of the fruit accelerates while when the
humidity is too low the fruit dries out.
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 161/239
Basic principles
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 162/239
p p
Immediately after the cut the bananas are stored in boxes or on pallets and are loaded ASAP.
The holds are cleaned and disinfected
(permanganate). N2 installations take care of theodours in the holds and eventual parasites
The holds are cooled down till 6°C before loading
The loading temperature of the banana is between
20°C and 30°C => the temperature in the hold will become > 12°C
The banana boxes are stowed in a very compactway
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 163/239
Basic Principles
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 164/239
p
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 165/239
Loading bananas – by hand
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 166/239
g y
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 167/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 168/239
Palletised cargo
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 169/239
Pallets are loaded
through horizontal or
vertical openings in
the hold
Pallets are loaded with
a pallet cage or cradle
Pallets are positionedin the holds by means
of forklifts
Palletised cargo
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 170/239
Palletised cargo
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 171/239
Palletised cargo
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 172/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 173/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 174/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 175/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 176/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 177/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 178/239
Partly filled holds
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 179/239
Cooling of the holds
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 180/239
At the end of the 19th century deepfreeze ships
were developed
Temperature had to be low but not very exact
This kind of ships is not suitable for fresh products
(fruit, vegetables)
Next generation of ships controls the hold
atmosphere in every aspect Today – Poly-thermal ships – 25°C -> +13°C
Mechanical Cooling System
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 181/239
A. Evaporator
B. Compressor
C. Expansion valve De compressor compresses the
cooling medium => Temperaturerises (orange)
In de condensor the cooling mediumgives off heat and liquefies (dark
blue) After the expansian valve the
pressure drops => temperaturedrops. In the evaporator the heat isabsorbed (cooling)
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 182/239
Cooling systems
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 183/239
With bottom gratings
Without gratings
Cooling system with bottom
gratings
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 184/239
gratings
a. Evaporator
b. Ventilator
c. Nil
d. Robsonchannels
e. Cargo space
f. Nilg. Bottom
gratings
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 185/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 186/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 187/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 188/239
Overview of « CA » techniques
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 189/239
Maintaining N2 concentration
Injection of pure N2
Admission of IG Use of N2 separators
Increasing CO2 concentration
Injection CO2
Natural breathing of the fruit
Overview of « CA » techniques
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 190/239
Lowering CO2 concentration
Ventilation
Absorption
Chemical process Adsorption
Separation by means of a membrane separator
Increasing relative humidity
Injection mist droplets Natural breathing of the fruit
Steam injection
Evaporation of water
Overview of « CA » techniques
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 191/239
Controlling ethylene concentration
Potassium permanganate
Active carbon
Ozone
Ultra Violet
An increased CO2 concentration will undo the
ripening effect of ethylene. Most of the ships with« CA » do not have any means on board to control
the ethylene concentration
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 192/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 193/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 194/239
Porthole refrigerated containers
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 195/239
Porthole technology was developed before
the seventies and used on the North-South
routes which carried large volumes of
refrigerated cargo. The first generation of
container ships with porthole refrigerated
containers is now over 25 years old and will
soon be replaced by ships with a greater capacity for integral refrigerated containers.
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 196/239
Porthole refrigerated containers
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 197/239
Porthole containers are thermally insulatedand have two sealable openings on the endwalls (the portholes) through which cold air
can be blown into the container and warm aircan be extracted. The cold air is forced throughthe lower opening into the container, thendistributed throughout the load via the T-barfloor, and subsequently flows through the loadto the top of the container and is extractedthrough the upper opening.
Porthole refrigerated containers
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 198/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 199/239
Porthole refrigerated containers
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 200/239
Collective systems
1 refrigeration unit takes care of a group of containers
1 large unit is installed in the double hull of thecontainer vessel an refrigerates a larger block of containers
1 cooling unit per vertical column of containers
Individual systems Clip-on unit refrigerates 1 individual container
Porthole refrigerated containers
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 201/239
Cooler integrated in the double
hull
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 202/239
Central cooling unit
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 203/239
Vertical distribution of
cooled air
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 204/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 205/239
Porthole refrigerated containers
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 206/239
Porthole installation ashore
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 207/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 208/239
Individual systems
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 209/239
Clip on units – porthole containers
Mechanical refrigeration
Diesel aggregate
Gasoline or LPG aggregate External electrical supply
Units using liquefied N2 or CO2 – obsolete
Temperature is maintained by injecting liquefied N2 or CO2
The gas is stored in an isolated reservoir fixed at the outside of
the container
Temperature is monitored by a sensor
Porthole refrigerated containers
Container with clip on unit
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 210/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 211/239
Porthole versus integral
refrigerated containers
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 212/239
Integral refrigerated containers
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 213/239
In contrast to porthole containers, integral
refrigerated containers are equipped with
their own refrigeration unit.
Cold air flows through and around the
goods in the container. This air is blown in
through the gratings in the floor and then
drawn off again below the container ceiling.
Integral refrigerated containers
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 214/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 215/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 216/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 217/239
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 218/239
Componenets of an integral
refrigerated container
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 219/239
Rear en of an integral
refrigerated container
Circulating fans (2)
and air cooler (17) areclearly visible
Cooling circuit with additional
water cooled condensor
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 220/239
Connections for the additional
water cooled condensor
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 221/239
Cooling the
condensers with water
is a solution to get rid
of the heat when thereefers are stored
beneath deck
Fresh air
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 222/239
When transporting vegetables or fruits theCO2 and ethylene generated during theripening process must be removed
This is achieved by ventilation The amount os fresh air is < 2 times the
volume of the container per hour
Exception when using CA (ControlledAtmosphere)
Fresh air
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 223/239
Fresh air flap
Discs to fine tune the
quantity of fresh air
administered
Atmosphere sampling
point
Coolants
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 224/239
Originally, all refrigerated containers wereoperated using the coolants R11 and R12. After the destruction of the ozone layer became an issueand consequently these coolants were banned bythe Montreal Protocol, a number of manufacturersswitched briefly to R22 as a substitute coolant.However, as this is also being phased out, the twocoolants R134a and R404a are now generally used
instead.
Data loggers - local
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 225/239
Temperatures are stillrecorded today for use asevidence in the event of adamage claim, mainly
with circular temperaturecharts, which generallycover a period of 31 daysThe return air temperatureis generally recorded on
these charts.
Data loggers - local
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 226/239
Due to the progress made in data technology, many moderncontrollers are able to store their measured values on dataloggers. The storage period is generally one year. The main
benefit of this type of data logger is that it records not only the
return air temperature but also the supply air temperature andUSDA temperatures. In addition, they can register alarms, onand off times and manual intervention.One disadvantage of the data loggers is that they only supplydiscrete values and do not provide the crew with a quick
overview of the history of a particular refrigerated cargotransport. In addition, it is often difficult in the event of adamage claim to localize the container and have the contents of the data logger read out.
Data loggers - local
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 227/239
Nowadays, several data
loggers are often also
placed within the load
when transporting
refrigerated goods. Theseare used to monitor the
temperatures inside the
container during transport
and allow this data to bemade available to the
recipient of the goods.
Remote controlling
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 228/239
With an increasing number of integral refrigerated
containers being used in maritime transport, there is also a
greater need for effective ways of monitoring these
containers. On ships, many of which can nowadays
transport over 1,000 integral refrigerated containers, usinga remote monitoring system can cut the costs of inspecting
the containers while also enabling the crew to react more
rapidly to potential problems in the event of a refrigeration
unit failing.
Remote monitoring
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 229/239
Nowadays 2 techniques are used for remotemonitoring. Both are using electrical cables andstandard sockets. – PCT = Power CableTransmission Narrowband transmissions
Wideband transmissions
ISO 10368 standard for data exchange – no agreementwas reached for the frequencies (narrow or wide band).
Following values are monitored Compressor running
Defrost
Temperature in range
Remote monitoring
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 230/239
Around 80-90 %of all refrigeratedcontainers have a
socket to connectthem to this typeof monitoringsystem.
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 231/239
Example of
datalogger extract
Data loggers
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 232/239
These loggers can provide evidence of
periods of insufficient refrigeration leading
to damage. For certain highly sensitive
products (for example, blood plasma) the
use of such loggers is required as proof that
the cold chain has not been broken at any
time.
Remote monitoring
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 233/239
It is expected that it will bepossible to transmit data by radiofrequency in the future, e.g. using
"wireless LAN" technology.
CA-containers
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 234/239
The use of CA extends the storage life of fruit andvegetables not only through cooling, but also by changingthe air composition in the space (container) in which the
goods are located. This generally involves reducing
the oxygen content to 1 - 3 % (normal air:21%) and increasing the carbon dioxidecontent to 5 - 25 % (normal air: 0.03%). Thecomposition of the atmosphere that produces the longest
possible storage life primarily depends on the type of fruit,the variety, its origin and the time of harvest.
CA-containers
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 235/239
The correct atmosphere will slow respiration inthe fruit , thus ensuring longer storage life. Fruitrespiration can be reduced by around 30 - 60 % incomparison with normal atmospheric conditionswith CA. This, of course, means that transporttimes can be extended, so that fruit, for instance,that is normally transported by air can also betransported by sea in refrigerated containers.
Another possibility is to harvest the fruit later andhence achieve better quality fruit.
CA-containers
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 236/239
Reduction of O2 is achieved by inerting the
container with N2
CO2
can be increased by injecting CO2
Production of N2
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 237/239
Membrane generators
PSA = Pressure Swing Absorption
Membrane generators
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 238/239
The membrane consists of a polymer that is permeable todifferent degrees for different gases. In principle, almostall gases can pass through the membrane, but at different
permeation rates. For the gases involved in CAapplications, the following applies: Water vapor permeatesfastest, followed by CO2, O2 and finally N2.
PSA - generators
7/28/2019 Theorie Part 2 Air Treatment
http://slidepdf.com/reader/full/theorie-part-2-air-treatment 239/239
Oxygen is bound by
the active carbon
under high pressure
and released againunder low pressure
The carbon filters
top related