2015 11-19-energy efficiency efficient use of raw materials

Detlev Matzdorf, Nov 2015, Sirris, Gent

Welcome to Sirris

workshop: Energy efficient peripherals and ancillaries

in plastics processing

Gent Meeting Center, Nov. 18th 2015

Subject: Energy efficient use of raw materials

Speaker: Mr. Detlev Matzdorf

motan-colortronic GmbH

Otto-Hahn Str. 14

D-61381 Friedrichsdorf


Energie efficient use of raw materials

Where to save energy in the material handling process

- Where to save energy in the material storage process

- Where to save energy in the drying process

- Where to save energy in the conveying process

- Where to save energy in the dosing process

- Where to save energy in motor design


Where to save energy in the handling process

If possible, heat the

material on the

machine material inlet Prevent the

material from

re-moisturing

Preheating the

silo with

exhaust heat

Use the right drying

parameters (airflow,

dew point, temperature

and residence time )

for your application.

Dryer Bin Bin

Octabin

M

Moulding M.

Outdoor silo

Improve the efficiency

of the screw drive

of the moulding

machine

Prevent the material

from recooling

Convey the material

energy efficient


Parameters which influence energy consumption

1. Summer – Winter

changing ambient humidity

changing material temperatures

2. Changing humidity in material supply.

3. Changing drying parameters

- temperature difference between drying temperature

and return air temperature

- dew point for material drying

- material data (cp value) related to specific dry air flow

- changing demand of the connected machines

4. conveying process

5. use of right motors ( please refer to the lecture of

Kurt Muylaert, Danfoss)


1. Initial moisture in granules, Summer – Winter relation

Spring Summer Winter Autumn

Moisture content of the material in relation to

the season

Required rest humidity for production

If plastic granulates are stored in ambient air, it always adapts to the moisture content of the

environment until the moisture of the material and environment is equal.


The specific air flow rate must be adapted

to the material inlet temperatures!

The colder the material, the more air

and energy is needed, in order to

heat up the material to a final

temperature.

Example: In order to heat up a material in

winter time from –10 °C to 175 °C with a

constant exhaust air temperature of 62 °C,

we need a specific dry air flow of 2.7 m³/kg

and 104 Wh/kg of energy will be consumed.

Same case in summer : at 20 °C material

inlet temperature, 2.27 m³/kg air flow will be

sufficient to heat up the material to

175 °C, with an energy consumption of

88 Wh/kg with an exhaust air temperature

of 62 °C.

1.1. Material inlet temperature in relation to the

specific air flow and the energy consumption

1,8 1,92 2,05 2,18 2,30 2,43 2,55 2,68 2,80

Specific dry air flow [m³/kg]

Energy usage and specific dry air flow in relation to the material inlet

temperature

-20

-10

0

10

20

30

40

50

70 75 80 85 90 95 100 105 110

Energy usage [Wh/kg]

Mate

rial

inle

t

[°

C]

Autumn / Fall

Summer

Winter


Dryer Bin Bin

Octabin

M

Processing machine

T1a T1b

T3

T4 T5

T2

0,2%

0,4%

0°

0,5%

Delivery of pre-

dried material

Winter

Summer

Re-moisturing

dependent on the

storage time and

ambient moisture

More or less drying

performace required

T2 T1 T4 T5

Re-moisturing

dependent on the

storage time on the

machine bin

Outdoor silo

T0

T3 T0

0,3%

0,1%

Note : Drying systems are always rated for the worst case of maximum material

moisture, minimum inlet temperature and maximum throughput. Solution is: ETA²

1.2. Re-moisturing of the material in a standard production


- Prevent the material from re-moisturing! The material stays for hours or weeks in the outdoor silo or other storage vessels. Keep the material in a dry environment.

- For every % of moisture the material absorbs, you have to spend another 25 Watt hours/kg to

remove it!!

Dry air

generator Outdoor silo Use exhaust heat

from production

2.2. Prevent material re-moisturing in the outdoor silo or

octabin.

Dry air quantity for blanketing

per m³ silo volume = 1m³/h dry air flow


2.3.1. Efficiency of material heat up of heating with hot air

in comparison to heating up by friction by the screw.

Example: to heat up material from 40°C to 120°C we need energy:

- by using friction : 1 kg x 1,2 kJ / kg K x 80°K / 0,49 efficiency / 3,6Wh / kJ = 54,4 Wh/kg

- by using hot air heat up with electric heater : 1 kg x 1,2kJ/kg K x 80°K /0,8 Wirkungsgrad /3,6Wh/kJ = 33,3 Wh/kg

By heating the material on the machine from 40°to 120°C the energy consumption can be

reduced by 38.8 % only for this part of process.

ProcessingE-Motor

Hydro-drive

= Efficiency

E-Motor

= 0,85

Hydro pump

= 0,80

Tubes and

Valves = 0,90

Hydro drive

= 0,80

Total efficiency for

heating with electrical

heater incl. blower = 0,80

Total efficiency for

heating with friktion = 49%

( 0,8 x 0,9 x 0,8 x 0,85 = 0,49 )


2.3.2 Small application of material drying on the machine

M

Moulding

Dryer Bin

Re-cooling of the

material due to

conveying and storing

in the machine hopper

Dryer

Bin

M

Moulding

Heat exchanger

Heater No loss of

heat

100°

200°

0°

250°

T1a Winter

T1a Summer

T1

T2

Cooling by

conveying

with cold

ambient air

Cooling by storing

the material in the

machine hopper

T3 T4 T5

Heating to 230° by friction and heating

LOSS

Drying

phase

100°

200°

0°

250°

T1a Winter

T1a Summer

T1

T2

Material gets hot

by drying

T4 T5

Heating to. 230° by Friction und heating

No conveying

no cooling

T2

T2

T4

T4

T5

T5

T3

T1 Winter / Summer

Drying

phase

With two conveying steps we need approx. 10% of specific energy use for

conveying


2.4 Energy consumption comparison of drying Nylon PA 6

The comparison of the energy usage shows the real benefit of a conditioning process at 60°C with reduced

airflow for Nylon in relation to standard drying at 80°C and full airflow.

- No over-drying or too wet material

- only half size dryer needed and application with low air flow

Energy calculation comparison

Standard drying

at 80°C

Conditioning at

60°C

Material throughput: Kg/h 500 500 Kg/h

Dry air generator LUXOR 1200 600

Dry air fow with ETA plus 950 450 m³/h

Energy usage of a drying system for PA 6 63,2% % Savings

Energy consumption of the system 15,3 5,6 kW

Spezific energy usage = 30,5 11,3 Wh/kg

Cost in Cent / m³ dry air 0,1608 0,1250 Euro Cent / m³

Total cost in 8000 h per year 12219,44 4500,70 Euro/year

Standard drying at

80°C

only conditioning at 60°C

Blower 9,7 5,2

Heater 11,7 3,0

Regeneration 9,2 3,0

0,0

5,0

10,0

15,0

20,0

25,0

30,0

35,0

Standard drying at 80°C only conditioning at 60°C

En

erg

y u

sag

e [

Wh

/kg

]

Energy usage of drying or conditioning of PA 6

Regeneration

Heater

Blower


3.1. Desiccant bed dryer with automatic

energy saving technology

- Preheating of regeneration air

with heat exchanger

Reduction of energy usage

- Temperature controlled

regeneration

Energy efficient load related

heating process

- Dew point control

Reduced quantity of regeneration

Cycles = energy saving

- Insulated desiccant bed Reduced heat radiation during the

heat up phase

Drying process:

- Frequency controlled process air blower

Enables load-related energy

consumption

Regeneration process:

Advantages:

- Return air controlled

dry air flow

Best way to control the energy

requirement of the drying process

- Dew point control Defined maximum process dew point


3.2. Elements of ETA plus drying process

ETA plus AFC frequency

controlled drying process

blower.

Measurement of the

exhaust air °C, °F

Difference pressure

measurement

Motor valve on every

drying bin

Optional ETA plus heat exchanger

for high temperature and high

airflow solutions

Heater close to the bin air

inlet

M

Heat exchanger for

regeneration air heating up

Dew point controlled

regeneration bed switch

cycles

Separated bed switch

valve blocks for

minimum heat loss Fully insulated drying bin

Closed loop recooling with active

cooler, in order to prevent the desiccant bed from re-moisturing. Up to 30% more dehumidification

power in comparison to ambient air recooling

Fully separated process air circuits for regeneration

and material drying

motan


Temperature profile in drying systems with and without ETA plus heat exchanger

Drying temperature (°C)

Blower

Trockentrichter

Dryer

Mate

rial

Heat

reclamation

25%

Heat

exchange

return air

Dry

air

heating

Heat

exchange

process air

Molecular sieve

Air / air aftercooler

200°C / 392°F

0°C / 32°F

180°C / 356°F 160°C / 320°F 140°C / 284°F 120°C / 248°F 100°C / 212°F 80°C / 176°F 60°C / 140°F 40°C / 104°F 20°C / 68°F

3.2.1. Comparison of drying systems


In drying systems it frequently occurs that the material throughput in

the drying process is changed due to tool change or switching off

some cavities

What would be an intelligent reaction to changing material

throughputs in the drying bin?

Should we lower the level in the bin to keep the residence time

constant?

Should we reduce the air flow?

Should we… ??

3.3. drying process with automatic air flow control


The ETA plus air flow control is an automatic system for efficient regulation

of the air flow and drying temperature in every single drying bin related to the

material throughput.

Main criteria:

• Reduction of the energy consumption by adjustment of the airflow

and drying temperature to the material throughput

• Material-protective drying procedure

(avoiding material damage by drying for too long)

• Adaption of the drying performance to different material inlet

temperatures: Summer / Winter - Day / Night

3.4. Main criteria for the automatic airflow control ETA plus


M M

m o

t

a n M E

T

R

O

m o

t

a n M E

T

R

O

1 2

3.5.1. Main elements of the air flow control

Frequency controlled

drying process blower Hz

Measurement of the

exhaust air temperature

°C

Measurement of pressure

difference between process and

return air

Motor valve for air

control on every drying

bin

Today the air flow control is regarded as the most important system

to adapt the energy consumption of the drying process to the

material drying requirements!

NOTE: The main set value for air

flow control is the return air

temperature at the drying bin.

For 71 materials, a default value of

the return air set value is stored in

a data base.

Normally the return air set value is

around 45% of the heating

temperature.


3.5.2 Coherence of air flow and temperature control

20

40

60

80

100

120

140

60

80

100

120

140

0 10 20 30 40 50 60 70 80 90 100

Material throughput [ % ]

Temperature°C

Air flow %

Air flow

[ % ]

Drying-

temperature

[ °C ]

50°C

120°C

50°C

120°C

100 kg/h 200 kg/h

medium high

50°C

108°C

50 kg/h

low

65°C

80°C

0 kg/h

low Air flow

Heater temp.

Exhaust

air temp.

Material 20°C Material 20°C Material 20°C No Material

The new ETA plus

process includes a

combined air flow and

temperature control for

maximum energy

efficiency and safe

material drying.

Motan ETA plus drying

system guarantees

maximum of energy

effectivity and at once

safety against material

damaging or over drying


3.5.3. Results of changing the material throughput

without adjusting the drying parameters

Energy balance:

If more energy is supplied than

removed, the temperature

gradient moves to the top of the

silo!

Consequence: High exhaust air

temperatures, long residence

time at high temperatures

= material degradation!

A lot of cooling energy is

needed to cool the hot exhaust

air for dehumidification in the

dryer!

= Not a good solution!

Return air

temp. 62

°C

Material IN

20°C

1000 kg/h

Heating temp.

175 °C

2280 m³/h

Energy

usage

88 Wh/kg

Material

outlet temp.

172°C

Return air temp.

108 °C Material IN 20 °C

600 kg/h

Heating temp.

175 °C

2280 m³/h

Energy

usage

137 Wh/kg

Material

outlet temp.

175 °C

Reduction of the

material throughput


3.5.4. Best solution with air flow control at full bin level

Maximum material level

and air flow control

Return air

temp. 108

°C

Material IN 20

°C

600 kg/h

Heating temp.

175 °C

2280 m³/h

Energy usage

79 Wh/kg !!

Return air

temp. 55

°C

Material IN 20 °C

600 kg/h

Heating temp.

175 °C

1230 m³/h

10h

4h

Energy usage

137 Wh/kg

Lower air temperature reduces the

cooling water requirements of the drying

process.

No material degradation, because in

the last 4 hours only the temperature

is above 120 °C!

Through improved efficiency, the air

flow can be reduced to 1230 m³/h.

The full bin causes a 66% larger

heat exchange surface between

bulk material surface and dry air

for material heat-up!

No material center flow!


3.5.5. Best solution with air flow control at full bin level

Summary:

What to do with variable material throughput?

1. Do not reduce the material level!

2. Full bin for better heat transfer!

3. Using the Eta+ air flow control!

4. Avoid expensive equipment!

5. Reduced energy consumption from 137 to

79 Wh / kg = 42%!!

Energy usage

79 Wh/kg !!

Return air

temp.

55 °C

Material IN 20°C

600 kg/h

Heating temp.

175 °C

1230 m³/h

10h

4h


Motor Motor

Pressurized

+ -

T1LMR T2LMR

T3LMR

Air flow process air

Air flow process return air

Motor

by blower

Filter

Desic

can

t b

ed

The diagram shows a drying

system with dryer and 2x 600

liter and one 300 liter drying bin.

The blower generates the air

flow in the system, in order to

get a constant pressure in the

process duct work.

At every drying bin a throttle

valve is installed to set the

airflow to the right level.

Throttlling Throttlling

Pressure

drop in the

bulk

Pressure

drop in the

bulk

90%

45% 45%

Pressure difference

measurement between

process and return air

3.6. Diagram of a multiple bin drying system

with air flow control

Heater

Air flow meter


The comparison was carried out for PET drying systems. With variable material

throughputs, the range of energy saving can be from 24% to 64%.

3.7. Comparison of systems with ETA plus air flow control

and systems without energy saving features

0,00

10,00

20,00

30,00

40,00

50,00

60,00

70,00

1 2 3

En

erg

y u

sa

ge

[ k

W ]

Material flow [ kg/h ]

Energy usage of ETA systems with air flow control

260 390 520

Regeneration energy

Blower energy

Energy savings

Heating energy

0,00

10,00

20,00

30,00

40,00

50,00

60,00

70,00

1 2 3

En

erg

y u

sa

ge

[ k

W ]

Material flow [ kg/h ]

Energy usage of drying systems without energy saving features

Heating energy

Regeneration energy

Cooling Energy

Blower energy

260 390 520


3.8. Energy usage for drying of ABS with a LUXOR 120

In comparison to a conventional drying system you can save app. 35% to 50% of the

energy consumption by using a ETA plus drying system.

Even with a small LUXOR 120 savings of up to 900 Euro / year can be realized easily.

0

10

20

30

40

50

60

70

80

90

40 45 50 55 60 65 70 75 80

En

erg

y u

sa

ge

Wh

/kg

Material throughput kg/h

Energy usage of a LUXOR A 120 for ABS with Eta plus and conventional

ETA plus ABS

Konv. ABS

ABS ETA plus

ABS conventional

20,0%

30,0%

40,0%

50,0%

60,0%

40 50 60 70 80

En

erg

y sav

ing

%

Material throughput kg/h

Procentage of savings of LUXOR 120 with ETA plus

Specific energy usage! Wh / kg Absolute energy usage = kW


Reduction of energy consumption in the

regeneration process by drying with

adequate dew points

Low dew points costs a lot of money!


3.9.1. The regeneration process

Additional features that reduces the numbers of

regeneration cycles:

- Dew point controlled regeneration

-Constant dew point regulation ATTN

-Closed loop re-cooling

Features that reduces the energy usage directly:

-Temperature controlled process steps

-Heat exchanger in the heat up loop

How to optimise the regeneration process?

1. Use of sufficient dew point set value increased water intake of the desiccant bed

2. Goal: Increased water intake of the desiccant bed reduced numbers of regeneration cycles

3. Reduced numbers of regeneration cycles lower total energy consumption


Drying with adequate dewpoints and not with the lowest possible dew point!

An adequate dew point can increase the drying capacity by 133%!

Dew point

Dry air temperature (molecular sieve temp. = process - return air)

Water adsorption

With a maximum

dew point of –40

°C only 6%

adsoption

With a maximum

dew point of –20

°C 14% adsoption

-50 °C / -58 °F

-40 °C / -40 °F

-30 °C / -22 °F

-20 °C / - 4 °F

50 °C

122 °F

150 °C

302 °F

200 °C

392 °F

100 °C

212 °F

250 °C

482 °F

3.9.2. Reduction of energy usage by using

sufficient dew points


Reduction of number of regeneration cycles leads to 20% energy savings by

the use of higher, but sufficient dew points

Energy consumption with different bed switch cycle

times

800

850

900

950

1000

1050

1100

1150

1200

3 4 5 6 8 10 12 14 16 18 20 22 24

Bed switch cycle time ( 6 . . . 24 hours )

To

tal en

erg

y c

on

su

mp

tio

n

( K

W p

er

day )

Reduction of 225

KWh per day

By changing the

maximum dewpoint

from -40 to -20 °C it

was possible to reduce

the total energy costs

of 20% - only by

increasing the bed

switch cycle time.

From 3 to 10 hours.

The test was carried through at

IFAP in Italia.

3.9.3. Reduction of regeneration cycles saves energy


3.10 Automatic constant dew point

control ATTN for drying systems


3.10.1. Quality losses by over- and under-drying

Moisture content directly affects the viscosity of the melt:

- If the residual moisture is too low, this leads to a tough melt, which increases shearing

in the material and causes a higher drive power of the machine. That leads thereby to a

material damage and to a reduction of the intrinsic viscosity.

- A too high moisture content in the melt phase lowers down the friction, but increases

hydrolysis and also leads to a material damage and to a reduction of the intrinsic

viscosity.

- Only with optimal humidity content the damage is low.

low Moisture content Too high

Degree of

damage

Damage through

friction due to too

tough melt

Damage by vapour

through hydrolysis

Optimum

moisture

content


min. moisture 0,03 0,03 0,03 0,03 0,03 0,03 0,03 0,03 0,03 0,03 0,03

Drying of NORYL GTX at production ( from 2,5 h) up to standby ( >> 2,5 h)

0

0,05

0,1

0,15

0,2

0 0,5 1 1,5 2 2,5 3 3,5 4 4,5 5 5,5

Drying time [h]

Res

idu

al m

ois

ture

[%

]

- 15 °C / 100 °C production

Eta plus on mimimum

- 5 °C / 60 °C standby

Eta plus on maximum

max. moisture

min. moisture

3.10.2. Procedure of the constant dew point control

The combination of ATTN and ETA plus enables a safe drying process. ATTN avoids material from over drying.

ETA plus function controls the drying speed related to material throughput.


Conventional systems

0 1 3 7

-10

-20

-30

-40

T (c°)

t (h)

Motan dew point control

0 1 3 7

-10

-20

-30

-40

T (c°)

t (h)

Overdrying is effectively avoided!

- Low shear rate of the material melt by uniform water content below 30 ppm.

- Reduced degradation of the material = less AA value

- Lower power consumption of the production machine = energy savings

Advantage of an adjustable dew point!

3.10.3. Automatic constant dew point control

14 °F

-4 °F

-22 °F

-40 °F


Dew point in relation to the bypass position

Set dew point -15 °C / 5 °F

Fresh desiccant bed Wet desiccant bed

Dew point control with a

valve positioned in front of

the desiccant bed .

This valve mixes return air

and dried air to process

air with a constant dew

point .

3.10.4. Automatic constant dew point control

32 °F

5 °F

-22 °F


Kapitel 1 Grundlagen der

Trocknung

4.1 Material conveying systems


4.1. Material conveying systems

- conventional central vacuum systems

grown factories with additional maschines

different vacuum systems for different machine lines

Vacuum pumps with fixed speed

- Advantages of conventional central vacuum systems

step by step installation with growth of factory.

low investment costs for small throughputs

- disadvantages of conventional central vacuum systems

power loss due to blower after-run, switching on/off, current peaks during

start-up of the blower

only one hopper loader can be served at one time

large number of installed vacuum pumps and filter

required maintenance for large amount of blower


4.2. material gentle conveying for

reduction of material degregation and

reduction of energy consumption of

vaccuum pumps


model comparison

Car driving material conveying

always full speed blower / pump ON/OFF

accelerator pedal

cruise control

Speed adjustable pump

Airflow - control

4.2.1 material gentle conveying


Strong differences in pipe

lengthes of material-lines

the air speed will be automatically

controlled independently of line

resistance

conveying with controlled conveying velocity

4.2.4 material gentle conveying


simple operation

1. one-time configuration at initial start up,

2. On demand fine trimming and saving of pump speed

during operation with + - buttons; D Rohr mm 45

4.2.6. material gentle conveying

reduced energy consumption for conveying

energy consumption increases with the conveying velocity quadratically !

Q = density x velocity² / 2

therefore: even small speed reductions bring significant energy savings!

•reduced wear on pipes, elbows, hopper loader

• reduced maintenance and repair costs

• reduced material degregation ( angel-hair, dust )

speed + -


1. Connection hopper loader – vacuum line

2. Raw gas line

3. Central filter

4. Clean gas line

5. Frequency controlled vacuum blower

6. Control for permanent central vacuum

4.3.1 permanent central vacuum


4.3.2 Example of existing installation

Various Examples Rehau / Visbek



Example of a floor plan

Big Safety Filter with 29 m² filter surface

Frequency controlled blower up to 18.5 kW



- Field of application for a permanent central vacuum system

High conveying performances (long distances, high number of consumers)

Air volumes of approx. 800m³/h – 18.000m³/h

- Advantages of a permanent central vacuum system

Generation of vacuum depending on the consumption and therefore energy

savings up to 30 - 50% compared to a standard central conveying system

with line blowers

High conveying performances due to the fact of simultaneous conveying of

severals hopper loaders

Reduced power loss due to no blower after-run, no switching on/off, no

current peaks during start-up of the blower

Significantly simplified maintenance due to the fact of less installed blowers

and filters


5. use of right motors

- use of right motors ( please refer to the lecture of

Kurt Muylaert, Danfoss)

Please remember for future installations or revamping

purchasing costs of a motor cover only 2 – 3 % of the overall lifetime costs

due to energy demand.

A motor with demand oriented control will pay off within a short time.


Contacts

interested in more Details ?

Please contact

ORA Machines N.V.

Mr. Philippe Philips

Ambachtenzone Haasrode 3301

Ambachtenlaan 35

BE-3001 Heverlee

[email protected]

+32-16-400-383

Kapitel 1 Grundlagen der

Trocknung

mailto:[email protected]


Thank you for your attention !

2015 11-19-energy efficiency efficient use of raw materials

Technology