CO2 and O2 scrubbers
CO2 and O2 scrubbers
The CO2 scrubber
Fruit ‘breathes’: it uses oxygen (O2) and produces carbon dioxide
(CO2). If the concentration of carbon dioxide (carbonic acid) gets
too high, the quality of the fruit deteriorates. A CO2 scrubber can
prevent this because it removes the carbon dioxide from your
storage cells and ensures that the fruit retains its optimum
quality.
diagram 1
Regeneration
C02 bound to active carbon
dividing plate
sieve
The amount of carbon dioxide that must be removed or ‘scrubbed’
depends on various factors including the type of product, the
dimensions of the storage area and the conditions under which
the fruit is being stored. Once the required scrubbing capacity for
the connected storage cells is known, the desired level of carbon
dioxide can be maintained using the CO2 scrubber. VA offers a
range of standard CO2 scrubbers with capacities of 50 to 900 kg
per 24 hour period (at 3% CO2).
Absorption
diagram 2
Economical
The most important component of the CO2 scrubber is a steel
tank, with so-called active carbon, which binds carbon dioxide.
The most common system
The most common system
The CO2 scrubber has a cycle of two activities:
• absorption: removal of the carbon dioxide by using an active
carbon filter;
• regeneration: cleaning the active carbon filter.
active carbon
active carbon
active carbon actually used
active carbon actually used
As a rule, more time is required for regeneration than for
absorption. The special single-tank-system from VA enables these
times to be set independently of one another. This system only
needs one pump and is, therefore, extremely efficient as well as
being very economical.
Efficient
The VA-scrubber is also an excellent example of efficiency in another
respect. When absorption is taking place, the carbon dioxide rich air is
fed in one direction by the active carbon. During regeneration, the
purified air goes through the tank in the opposite direction (see
diagram 1).
diagram 3
New generation of VA air distribution system
New generation of VA air distribution system
active carbon
active carbon
dividing plate
dividing plate
sieve
This so-called ‘counter flow principle’ guarantees efficient purification,
sieve
active carbon actually used
a shorter scrub cycle and an important increase in the capacity and
active carbon actually used
effectiveness of the CO2 scrubber. In addition, the active carbon is
fully utilised by the unique air distribution system in the tank (see
diagram 2 + 3) and VA therefore guarantees that the active carbon can
continue to be effective for long periods because the filter cannot
become soiled. This allows optimum usage to be gained from the
materials and, as a result, costs can be reduced.
Unique lung system
The VPSA O2-scrubber
Injection
The scrubber’s active carbon filter takes up carbon dioxide up to
During injection, the VPSA converts external air into nitrogen with
its saturation point during absorption. The purified air goes back
The VPSA O2 scrubber removes oxygen from the sucked out cell
air (circulation) or external air (injection) so that almost pure
into the cold store. During the last phase of the CO2 take-up, a
nitrogen is what remains. The VPSA (Vacuum Pressure Swing
indicates the capacity in m3. The capacity of a VPSA60, for example
small part of the purified air is stored in a flexible buffer – ‘lung’ –
Absorption) O2 scrubber is, therefore, also referred to as a
is 60 m3. When converting to 1% residual oxygen, the capacity is
without this leading to under-pressure in the storage cell.
nitrogen generator. The VPSA reduces the oxygen level in the
an average of 30% lower. In the case of a VPSA60, this is 39 m3.
a residual oxygen level of 1 or 3%. The type number of the VPSA
storage area after goods have been put into storage or after
After cleansing with ambient air, and removing the carbon dioxide
interim opening of the cell during the storage season. The VPSA
During circulation, the VPSA reduces the oxygen concentration in
from the active carbon, the ‘lung air’ is used to reduce the oxygen
technology is based on an energy efficient, low pressure technique.
the cell ± 30% quicker than when injecting. The advantage of
level in the tank with the active carbon filter to the level in the
The entry pressure is no higher than 1-1.5 bar and is produced with an
injection is however, that a cell can be kept at slight over-pressure
storage cell. This unique system, guarantees that the undesirable
oil-free blower. As a result, heavy air compressors are not required.
so that even ULO conditions (ultra low oxygen) are possible in a
storage room with a leak. Only one PVC pipe is needed for
inflow of oxygen into your cold store is minimised. The ‘lung
system’ has been the most frequently used and reliable system for
In addition, VPSA technology purifies the active carbon filter via an
injection. With the VPSA, you can switch between injecting and
over 20 years.
extremely effective vacuum technique, allowing the filter to remain
circulating and vice versa at any given moment.
completely free of dirt and moisture. Durability and energy
efficiency are important core values for VA and these have been
EcoBlue
incorporated into the VPSA O2 scrubber.
At the end of 2010, the new EcoBlue Line was launched for the
models VA50 - VA350 (see table 1). These scrubbers offer a strong
price advantage in comparison to earlier models. The accompanying
Residual oxygen concentration
EcoBlue Auto-ULO control (S950) measures and controls gas
conditions in up to 8 CA-/ULO cells. In addition to this, the control
Input (from the cell)
Output O2 scrubber
can read up to 2 temperature sensors per cell. Other control options
21,0
3
require an upgrade to the Comfort Line (see table 1).
10,0
2,0
5,0
1,5
1,5
0,8
The components:
Table 2 - Output VPSA in circulation mode
CO2 scrubber components:
• a steel tank with active carbon and air distribution system;
•a cabinet for internal process control, a minimum of S45 basic
Circulation
controls, built into the front of the machine;
•a flexible buffer made of PU film (‘lung system’). The buffer
A few plus points:
•energy-efficient as a result of the middle-pressure ventilator that
reduces energy costs by 30%;
•low maintenance as a result of the minimum amount of moving
parts;
•maximum life expectancy of the active carbon filter as a result of
system optimisation;
•minimal temperature increases in cell air as a result of a
considered ventilator choice.
Capacity with 1/3%
residual oxygen
(m3 hour-1)
Power (kW)
VPSA4
2,5
0,9
VPSA6
6,0/4,0
2,6
VPSA11
11,0/7,0
2,6
VPSA16
16/11,0
3,6
VPSA21
21/15,0
5,4
VPSA28
28/20
6,4
VPSA40
40/28
9,8
VPSA60
60/39
13,9
VPSA85
85/55
21
Table 3 - T
he VPSA O2 scrubber is available in a range
Type
Absorption capacity
(kg CO2 24 hour -1 with 3%)
Power (kW)
VA50*
50
1,1
residual oxygen level, however, reduces as the O2 in the storage cell
VA100*
70
1,1
reduces. Circulation is the most energy efficient mode for lowering
Plus points
VA150*
100
1,1
the oxygen level in a storage area. So-called pull-down time is an
• development and production managed by VA;
VA200*
150
1,1
indication of the time necessary for circulation to bring your storage
•up to 50% less energy consumption than PSA or membrane
enables extremely low (<0.5%) oxygen levels in the gas-tight
storage cell.
Type
A VPSA needs two PVC pipes for circulation to and from the cell
(sucking and returning). The VPSA’s output volume is constant. The
cells to the required levels.
VA350*
200
1,1
VA500**
250
2,6
VA600**
325
2,6
reduce the oxygen concentration to 5% and to 1.5%. This calculation
VA900**
450
2,6
does not take cell leakage and respiration of the product into
**
VA1000
550
3,1
account.
VA1200**
650
3,1
VA2000**
800
5,5
VA2500**
900
5,5
Table 1 - Shortened specification summary for CO2 scrubbers
*EcoBlue, upgrade to Comfort Line available
**Comfort Line
of capacities
generators;
•low pressure, so minimal wear and tear and limited
Our quotes contain two values, as standard: the time necessary to
maintenance costs;
•oil-free blower, giving maximum life expectancy and capacity
retention of O2 filter;
• circulation and injection modus in one machine;
• suitable for automatic or manual control (PLC).
Capacity
The all-in-one system is intended for a relatively small storage
capacity. We regard the limit as 800 tons but this is very dependent
on the type of product that is to be stored. The capacity of the
machines is limited so as to prevent the system becoming topheavy. The biggest all-in-one system houses a VA350 CO2 scrubber
(200 kg CO2 per day (24-1)), combined with a VPSA16 O2 scrubber
(16 m3 N2 with an oxygen level of 3%).
Energy consumption
Type
The all-in-one system
CO2
scrubber
(kW)
CO2 scrubber O2-scrubber
Absorption kg
Capacity N2
VPSA (kW) CO2 24 hour -1
in M3 hour -1
with 3% CO2
VA50VPSA11
1,1
2,2
50
11
VA50VPSA16
1,1
3,6
50
16
VA100VPSA11
1,1
2,2
70
11
VA100VPSA16
1,1
3,6
70
16
VA150VPSA11
1,1
2,2
100
11
VA150VPSA16
1,1
3,6
100
16
VA200VPSA11
1,1
2,2
150
11
VA200VPSA16
1,1
3,6
150
16
In 2004, VA introduced the so-called All-in-one system. This compact
system is particularly suitable for clients with a relatively small
Table 4 - Specification of various types of all-in-one system
storage depot of up to 800 tons. The system can operate a maximum
of seven storage cells. In this system, all the components of a CA/
ULO installation are united on one frame: a CO2 scrubber, a VPSA
Plus points
O2 scrubber, all cell valves, an air compressor, a measurement and
• a price advantage of 15% compared to separate components;
regulation system, gas measurement equipment, a calibration bottle
• all-in-one, but all the advantages of separate components;
and a printer. In addition, it is a ‘plug and play’ system and only the
•no longer necessary to have wiring, measurement hoses or
PVC pipes need to be attached after installation.
pressure hoses to individual cells;
•tested as ready-to-use system in our testing facility; even less
chance of disruptions;
A complete system
The CO2 scrubber and the VPSA O2 scrubber are the most important
components of this complete, all-in-one system. In addition the allin-one system incorporates S950 Auto ULO controls as standard.
But there is more. All cell valves are mounted on the back of the
system in a valve manifold arrangement and no longer, therefore,
need to be on the cell itself. The pipes to the individual cold stores
are connected to this valve manifold arrangement. There are
connections to both the CO2 scrubber and the O2 scrubber on the
other side of the register.
• remote service via modem;
• can be installed and connected by you.
Your dealer
Van Amerongen | Biezenwei 6 | 4004 MB Tiel | www.van-amerongen.nl | info@van-amerongen.nl | t. +31 (0)344 67 05 70
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