Heat Pumps

1. Hightemperatureheatpumps integrationin
industrial separationanddryingprocesses
Daniel Flórez-Orrego, Eduardo Antonio Pina, Meire Ribeiro Domingos, Shivom
Sharma, François Maréchal
daniel.florezorrego@epfl.ch
35th International Conference on Efficiency, Cost, Optimization, Simulation
and Environmental Impact of Energy Systems ECOS 2022
3rd – 7th July, Copenhagen, Denmark
École Polytechnique Fédérale de Lausanne

2.  Ammonia
2.0% energy consumption
1.3% of CO2 emissions
High
temperature
heat
pumps
integration
Florez-Orrego,
Daniel,
et
al.
2
Introduction
 Pulp
5.6% energy consumption
2.3% of CO2 emissions
 Large heating demand  Waste heat is an important byproduct.
 More stringent carbon regulations, need for decarbonization.
 Deployment of HTHPs may reduce CO2 emissions by 30 - 40%.
 NetZero 2050 roadmap IEA: 15-30% heating demand of light industries.

3. Florez-Orrego,
Daniel,
et
al.
High
temperature
heat
pumps
integration
1. Typical ammonia plant without heat pump integration
2. Alternative ammonia plant with heat pump integration
3. Typical pulp plant with multiple effect evaporation
4. Alternative pulp plant with mechanical vapor recompression
Processscenarios
3

4. Ammonia Plant
High
temperature
heat
pumps
integration
Florez-Orrego,
Daniel,
et
al.
4
1000 t/day
Processesdescription
Feedstock
consumption (NG)
21.69GJ/tproduct
Chemical process power
demand 1.56 GJ/tproduct
Refrigeration power
demand 0.35 GJ/tproduct
Min. cooling req. 7.44 GJ/tproduct
Min. heating req. 4.33 GJ/tproduct
CO2 avoided 1.42 tCO2/tproduct

5. Processesdescription
High
temperature
heat
pumps
integration
Florez-Orrego,
Daniel,
et
al.
5
Pulp Plant 880 tAD/day
Multiple effect evaporator
Feedstock consumption (Wood)
41.15 GJ/tproduct
Chemical process power demand
2.84 GJ/tproduct
Refrigeration power demand 0.00
GJ/tproduct
Min. cooling req. 2.24 GJ/tproduct
Min. heating req. 12.23 GJ/tproduct
Fossil CO2 avoided 0.00 tCO2/tproduct

6. High
temperature
heat
pumps
integration
Florez-Orrego,
Daniel,
et
al.
6
Mechanical vapor
recompression
Processesdescription Pulp Plant 877.8,5 tAD/day
Feedstock consumption (Wood)
41.15 GJ/tproduct
Chemical process power demand
2.84 GJ/tproduct
Refrigeration power demand 0.00
GJ/tproduct
Min. cooling req. 15.16 GJ/tproduct
Min. heating req. 25.37 GJ/tproduct
Fossil CO2 avoided 0.00 tCO2/tproduct

7. Process Modeling and Simulation: Aspen Plus v.11
Methods
High
temperature
heat
pumps
integration
Florez-Orrego,
Daniel,
et
al.
7
Energy integration framework: OSMOSE Lua
Minimum
Energy
Requirement
Equation
Oriented
Modeling and
Simulation
Sequential
Modular
Simulation

8. High
temperature
heat
pumps
integration
Florez-Orrego,
Daniel,
et
al.
8
Methods
Energy integration
Exergy method

9. Optimization problem: maximum revenue (incl. HP or MVR investment):
Methods
High
temperature
heat
pumps
integration
Florez-Orrego,
Daniel,
et
al.
9
         
   
,
,
_
8760
HPor MVR
r
Power
Chips Natural
Wood Power
Chips Wood Natural Oil Oil
Biomass Grid
Gas
Biomass Biomass Grid
Gas
Biomass
f y
R W Pulp Ammo
Ammonia
Pulp
Product Product
Product
Z Ann factor
f B c f B c f B c f B c f W c
f B c f B c
 


       
    
Min
  2
2
CO
nia CO
Product Marketed
Marketed
f m c
 
 
 
 
 
 
 
 
 
 
Subject to:
, , 1
1 1
0 1..
N N
r r
i r r
i
f q Q R R r N

 


 
     
  exp
1
0
N
net imp
chemical
units
f W W W W

 

   
 
max,
min, y y 1..
f f f N
    
 
    1 1
0, 0, R 0
r
N
R R 
  
exp
0, 0
imp
W W
 
w = {utility units, resources}, yw existence (binary) and fw load factor variables
cNG=0.032 EUR/kWh; cEE=0.07 EUR/kWh; cOil= 0.018 EUR/kWh; cChips= 0.016 EUR/kWh; cWood=0.013 EUR/kWh; cNH3=0.098
EUR/kWh; cPulp=0.144; EUR/kWh; cCO2market=0.0084 EUR/kg;

10. High
temperature
heat
pumps
integration
Florez-Orrego,
Daniel,
et
al.
10
Methods

11. Performance indicators:
 Exergy efficiency
 CO2 emissions (direct + indirect):
 Revenues:
Methods
Florez-Orrego,
Daniel,
et
al.
11
,
,
or
ex
ammonia pulp
consumed ideal
Power
consumed actual natural gas oil wood chips
Grid
B B
B
B B B B B W
  
   
2
2 2
2
,
,
2, ,
,
Product Product,
,
1
3600
1000 1000
CH
Power CO Power
CO CO i i
Grid Grid i
Spec i CO i
CH
Wood Chips i
i
Natural gas Oil
f W r
t r b
B
f I
t m
b
CO
 
 
 

   
   
 
   
 
   
 
 
 
   
   
2
2
,
Exp/Imp
, ,
,
Ammonia, Natural gas, Oil,
Pulp Chips,Wood,
Product
,
Exp/Imp
Revenue
Power
Grid
i
Product i Product i
Product i
Product
HPor MVR
Power
CO
CO Grid
Marketed
Marketed
f B c f B c
EUR
t Z Ann
f m c f W c
 
 
 
   
 
 

 

 
  

 
 
_
8760
factor

12. Typical ammonia plant without heat pump integration
Resultsanddiscussion
High
temperature
heat
pumps
integration
Florez-Orrego,
Daniel,
et
al.
12
Overall exergy consumption 28.73
GJ/tproduct
ηex=64,75%
Grid power import 0.65 GJ/tproduct
No grid power exported
Fuel import (NG) 6.39 GJ/tproduct
Heat pump power demand 0.00
GJ/tproduct
Spec. CAPEX Heat Pump 0
EUR/tproduct
Total revenues 256.09 EUR/tproduct
Net fossil CO2 emitted 0.52
tCO2/tproduct

13. Alternative ammonia plant with heat pump integration
Resultsanddiscussion
High
temperature
heat
pumps
integration
Florez-Orrego,
Daniel,
et
al.
13
Overall exergy cons. 26.51 GJ/tproduct ↓ 8%
ηex=70.15% ↑ 8%
Grid power import 1.75 GJ/tproduct
No grid power exported
Fuel import (NG) 3.07 GJ/tproduct
Heat pump power demand 0.39 GJ/tproduct
Spec. CAPEX Heat Pump 2.55 EUR/tproduct
Total revenues 261.57 EUR/tproduct ↑ 2%
Net CO2 emitted 0.33 tCO2/tproduct ↓ 36.5%

14. NAME
EVENT
/
NAME
PRESENTATION
Speaker
14
 Overall exergy consumption 28.73 GJ/tproduct
 ηex 64.75%
 Grid power import 0.65 GJ/tproduct
 No grid power exported
 Fuel import (NG) 6.39 GJ/tproduct
 Heat pump power demand 0.00 GJ/tproduct
 Rankine power generation (BP) 1.47 GJ/tproduct
 Cooling tower power demand 0.17 GJ/tproduct
 Operating incomes 518.26 EUR/tproduct
 Operating costs 262.17 EUR/tproduct
 Spec. CAPEX Heat Pump 0 EUR/tproduct
 Total revenues 256.09 EUR/tproduct
 Fossil CO2 dir. emitted 0.37 tCO2/tproduct
 Fossil CO2 indir. emitted 0.15 tCO2/tproduct
 Net fossil CO2 emitted 0.52 tCO2/tproduct
 Overall exergy consumption 26.51 GJ/tproduct
 ηex 70.15%
 Grid power import 1.75 GJ/tproduct
 No grid power exported
 Fuel import (NG) 3.07 GJ/tproduct
 Heat pump power demand 0.39 GJ/tproduct
 Rankine power generation (BP) 0.70 GJ/tproduct
 Cooling tower power demand 0.13 GJ/tproduct
 Operating incomes 518.26 EUR/tproduct
 Operating costs 254.15 EUR/tproduct
 Spec. CAPEX Heat Pump 2.55 EUR/tproduct
 Total revenues 261.57 EUR/tproduct
 Fossil CO2 dir. emitted 0.18 tCO2/tproduct
 Fossil CO2 indir. emitted 0.15 tCO2/tproduct
 Net fossil CO2 emitted 0.33 tCO2/tproduct
Typical ammonia plant without heat
pump integration
Typical ammonia plant with heat
pump integration

15. Typical pulp plant with multiple effect evaporation
Resultsanddiscussion
High
temperature
heat
pumps
integration
Florez-Orrego,
Daniel,
et
al.
15
 Overall exergy consumption 42.13
GJ/tproduct
 ηex=45.91%
 No grid power import
 Grid power export 1.51 GJ/tproduct
 Fuel import (Chips) 0.00 GJ/tproduct
 Fuel import (Oil) 0.98 GJ/tproduct
 Heat pump power demand 0.00
GJ/tproduct
 Spec. CAPEX Heat Pump 0
EUR/tproduct
 Total revenues 583.19 EUR/tproduct
 Net fossil CO2 emitted 0.25 tCO2/tproduct

16. Alternative pulp plant with mechanical vapor recompression
Resultsanddiscussion
High
temperature
heat
pumps
integration
Florez-Orrego,
Daniel,
et
al.
16
 Overall exergy cons. 43.94 GJ/tproduct ↓ 4%
 ηex=43.94% ↓ 4%
 No grid power import
 Grid power export 1.48 GJ/tproduct
 Fuel import (Chips) 1.81 GJ/tproduct
 Fuel import (Oil) 0.98 GJ/tproduct
 Heat pump power demand 0.99 GJ/tproduct
 Spec. CAPEX Heat Pump 5.95 EUR/tproduct
 Total revenues 568.65 EUR/tproduct ↓ 3%
 Net fossil CO2 emitted 0.26 tCO2/tproduct ↑ 1%
Exergy of steam
vs. Electricity
Qdrying x Ө x Neffects < WMVR

17. NAME
EVENT
/
NAME
PRESENTATION
Speaker
17
 Overall exergy consumption 43.94 GJ/tproduct
 ηex 43.94%
 No grid power import
 Grid power export 1.48 GJ/tproduct
 Fuel import (Chips) 1.81 GJ/tproduct
 Fuel import (Oil) 0.98 GJ/tproduct
 Heat pump power demand 0.99 GJ/tproduct
 Rankine power generation (BP) 5.48 GJ/tproduct
 Cooling tower power demand 0.11 GJ/tproduct
 Operating incomes 736.14 EUR/tproduct
 Operating costs 161.53 EUR/tproduct
 Spec. CAPEX Heat Pump 5.95 EUR/tproduct
 Total revenues 568.65 EUR/tproduct
 Fossil CO2 dir. emitted 0.07 tCO2/tproduct
 Fossil CO2 indir. emitted 0.19 tCO2/tproduct
 Net fossil CO2 emitted 0.26 tCO2/tproduct
 Overall exergy consumption 42.13 GJ/tproduct
 ηex 45.91%
 No grid power import
 Grid power export 1.51 GJ/tproduct
 Fuel import (Chips) 0.00 GJ/tproduct
 Fuel import (Oil) 0.98 GJ/tproduct
 Heat pump power demand 0.00 GJ/tproduct
 Rankine power generation (BP) 4.42 GJ/tproduct
 Cooling power demand 0.07 GJ/tproduct
 Operating incomes 736.67 EUR/tproduct
 Operating costs 153.49 EUR/tproduct
 Spec. CAPEX Heat Pump 0 EUR/tproduct
 Total revenues 583.19 EUR/tproduct
 Fossil CO2 dir. emitted 0.07 tCO2/tproduct
 Fossil CO2 indir. emitted 0.18 tCO2/tproduct
 Net fossil CO2 emitted 0.25 tCO2/tproduct
Typical pulp plant with multiple effect
evaporation
Alternative pulp plant with mechanical
vapor recompression

18. Sensitivitytotheenergyinputcosts
High
temperature
heat
pumps
integration
Florez-Orrego,
Daniel,
et
al.
18
A B
C D

19. Sensitivitytotheenergyinputcosts
High
temperature
heat
pumps
integration
Florez-Orrego,
Daniel,
et
al.
19
For tax 0
0.01 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5
0.01 A B B B B B B B B B B
0.02 A C B B B B B B B B B
0.03 A D B B B B B B B B B
0.04 A D C B B B B B B B B
0.05 A A D C B B B B B B B
0.06 A A D C B B B B B B B
0.07 A A D D C B B B B B B
0.08 A A D D C B B B B B B
0.09 A A A D D C B B B B B
0.1 A A A D D C C B B B B
0.15 A A A A D D D D C C B
cGN
cEE
For tax 120
0.01 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5
0.01 A D C B B B B B B B B
0.02 A A D B B B B B B B B
0.03 A A D C B B B B B B B
0.04 A A D D B B B B B B B
0.05 A A D D C B B B B B B
0.06 A A A D D C B B B B B
0.07 A A A D D C B B B B B
0.08 A A A D D D B B B B B
0.09 A A A D D D C C B B B
0.1 A A A D D D D C B B B
0.15 A A A A A D D D D C C
cGN
cEE
Category of integrated
composite curve
Introduction of a high carbon
tax triggers the transition
towards heat pump integration.
Heat pump integration:
• when tax is 0 EUR/tCO2  only for
ratios cEE/cNG < 2.33
• when tax is 120 EUR/tCO2  as high
as cEE/cNG < 5

20. Sensitivitytotheenergyinputcosts
High
temperature
heat
pumps
integration
Florez-Orrego,
Daniel,
et
al.
20
For tax 0
0.01 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5
0.01 1 0 0 0 0 0 0 0 0 0 0
0.02 1 0 0 0 0 0 0 0 0 0 0
0.03 1 1 0 0 0 0 0 0 0 0 0
0.04 1 1 0 0 0 0 0 0 0 0 0
0.05 1 1 1 0 0 0 0 0 0 0 0
0.06 1 1 1 0 0 0 0 0 0 0 0
0.07 1 1 1 1 0 0 0 0 0 0 0
0.08 1 1 1 1 0 0 0 0 0 0 0
0.09 1 1 1 1 1 0 0 0 0 0 0
0.1 1 1 1 1 1 0 0 0 0 0 0
0.15 1 1 1 1 1 1 1 1 0 0 0
cGN
cEE
For tax 120
0.01 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5
0.01 1 1 0 0 0 0 0 0 0 0 0
0.02 1 1 1 0 0 0 0 0 0 0 0
0.03 1 1 1 0 0 0 0 0 0 0 0
0.04 1 1 1 1 0 0 0 0 0 0 0
0.05 1 1 1 1 0 0 0 0 0 0 0
0.06 1 1 1 1 1 0 0 0 0 0 0
0.07 1 1 1 1 1 0 0 0 0 0 0
0.08 1 1 1 1 1 1 0 0 0 0 0
0.09 1 1 1 1 1 1 0 0 0 0 0
0.1 1 1 1 1 1 1 1 0 0 0 0
0.15 1 1 1 1 1 1 1 1 1 0 0
cEE
cGN
Heat pump integration

21. Sensitivitytotheenergyinputcosts
High
temperature
heat
pumps
integration
Florez-Orrego,
Daniel,
et
al.
21
Efficiency as a function of the
natural gas and electricity
costs (and carbon taxes)
For tax 0
0.01 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5
0.01 70% 61% 61% 61% 61% 61% 61% 61% 61% 61% 61%
0.02 70% 65% 61% 61% 61% 61% 61% 61% 61% 61% 61%
0.03 70% 69% 62% 61% 61% 61% 61% 61% 61% 61% 61%
0.04 70% 69% 65% 62% 61% 61% 61% 61% 61% 61% 61%
0.05 70% 70% 69% 65% 61% 61% 61% 61% 61% 61% 61%
0.06 70% 70% 69% 65% 62% 61% 61% 61% 61% 61% 61%
0.07 70% 70% 69% 69% 65% 62% 61% 61% 61% 61% 61%
0.08 70% 70% 69% 69% 65% 62% 62% 61% 61% 61% 61%
0.09 70% 70% 70% 69% 69% 65% 62% 61% 61% 61% 61%
0.1 70% 70% 70% 69% 69% 65% 65% 62% 61% 61% 61%
0.15 70% 70% 70% 70% 69% 69% 69% 69% 65% 65% 62%
cEE
cGN
For tax 120
0.01 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5
0.01 70% 69% 65% 61% 61% 61% 61% 61% 61% 61% 61%
0.02 70% 70% 69% 62% 61% 61% 61% 61% 61% 61% 61%
0.03 70% 70% 69% 65% 62% 61% 61% 61% 61% 61% 61%
0.04 70% 70% 69% 69% 62% 62% 61% 61% 61% 61% 61%
0.05 70% 70% 69% 69% 65% 62% 61% 61% 61% 61% 61%
0.06 70% 70% 70% 69% 69% 65% 62% 61% 61% 61% 61%
0.07 70% 70% 70% 69% 69% 65% 62% 62% 61% 61% 61%
0.08 70% 70% 70% 69% 69% 69% 65% 62% 62% 61% 61%
0.09 70% 70% 70% 69% 69% 69% 65% 65% 62% 61% 61%
0.1 70% 70% 70% 70% 69% 69% 69% 65% 62% 62% 61%
0.15 70% 70% 70% 70% 70% 69% 69% 69% 69% 65% 65%
cEE
cGN

22. Sensitivitytotheenergyinputcosts
High
temperature
heat
pumps
integration
Florez-Orrego,
Daniel,
et
al.
22
Emissions as a function of
the natural gas and electricity
costs
For tax 0
0.01 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5
0.01 0,329 0,654 0,654 0,654 0,654 0,654 0,654 0,654 0,654 0,654 0,654
0.02 0,329 0,523 0,654 0,654 0,654 0,654 0,654 0,654 0,654 0,654 0,654
0.03 0,329 0,336 0,637 0,654 0,654 0,654 0,654 0,654 0,654 0,654 0,654
0.04 0,329 0,336 0,523 0,637 0,654 0,654 0,654 0,654 0,654 0,654 0,654
0.05 0,329 0,329 0,336 0,523 0,654 0,654 0,654 0,654 0,654 0,654 0,654
0.06 0,329 0,329 0,336 0,523 0,637 0,654 0,654 0,654 0,654 0,654 0,654
0.07 0,329 0,329 0,336 0,336 0,523 0,637 0,654 0,654 0,654 0,654 0,654
0.08 0,329 0,329 0,336 0,336 0,523 0,637 0,637 0,654 0,654 0,654 0,654
0.09 0,329 0,329 0,329 0,336 0,336 0,523 0,637 0,654 0,654 0,654 0,654
0.1 0,329 0,329 0,329 0,336 0,336 0,523 0,523 0,637 0,654 0,654 0,654
0.15 0,329 0,329 0,329 0,329 0,336 0,336 0,336 0,336 0,523 0,523 0,637
cEE
cGN
For tax 120
0.01 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5
0.01 0,329455 0,33628 0,522696 0,653826 0,653826 0,653826 0,653826 0,653826 0,653826 0,653826 0,653826
0.02 0,329455 0,329455 0,33628 0,637015 0,653826 0,653826 0,653826 0,653826 0,653826 0,653826 0,653826
0.03 0,329455 0,329455 0,33628 0,522696 0,637015 0,653826 0,653826 0,653826 0,653826 0,653826 0,653826
0.04 0,329455 0,329455 0,33628 0,33628 0,637015 0,637015 0,653826 0,653826 0,653826 0,653826 0,653826
0.05 0,329455 0,329455 0,33628 0,33628 0,522696 0,637015 0,653826 0,653826 0,653826 0,653826 0,653826
0.06 0,329455 0,329455 0,329455 0,33628 0,33628 0,522696 0,637015 0,653826 0,653826 0,653826 0,653826
0.07 0,329455 0,329455 0,329455 0,33628 0,33628 0,522696 0,637015 0,637015 0,653826 0,653826 0,653826
0.08 0,329455 0,329455 0,329455 0,33628 0,33628 0,33628 0,522696 0,637015 0,637015 0,653826 0,653826
0.09 0,329455 0,329455 0,329455 0,33628 0,33628 0,33628 0,522696 0,522696 0,637015 0,653826 0,653826
0.1 0,329455 0,329455 0,329455 0,329455 0,33628 0,33628 0,33628 0,522696 0,637015 0,637015 0,653826
0.15 0,329455 0,329455 0,329455 0,329455 0,329455 0,33628 0,33628 0,33628 0,33628 0,522696 0,522696
cEE
cGN

23. Sensitivitytotheenergyinputcosts
High
temperature
heat
pumps
integration
Florez-Orrego,
Daniel,
et
al.
23
Revenues as a function of
the natural gas and
electricity costs
Natural gas costs > 0.07 EUR/kWhNG
make the system economically
infeasible, since natural gas is
also used as feedstock in the
ammonia plant (Pulp mills plant
have a broader operative range)
Revenues fall
by 18%
0 EUR/tCO2
70 EUR/tCO2
120 EUR/tCO2

24. Florez-Orrego,
Daniel,
et
al.
Conclusions
High
temperature
heat
pumps
integration
 Natural gas price > 0.07 EUR/kWh  NH3 production economically unfeasible (regardless of price of electricity and use of
steam network or heat pump  cost for the ammonia produced).
 Higher cost of natural gas  electricity to supply heating in a more efficient way (HTHPs)  Accentuated when the carbon
tax is increased.
 Electricity imported is used in the plant to balance the power generation of the steam network. When cEE/cNG ratio is large,
the system uses large amounts natural gas, hampering the cogeneration efficiency.
 In the pulp plant, the excess waste heat is such that there is no need for EE import, and rather surplus EE export is
evidenced.
 Steam consumption in a Multiple Effect Evaporator results more efficient than driving a Mechanical Vapor Recompression 
Profits self-power generation potential.
 How much exergy of steam and how much exergy of power to achieve the same task: Qdrying x Ө x Neffects < WMVR.
 Although installing a heat pump is not a warranty of higher efficiencies or revenues, it may bust efficiency in certain
applications.
24

25. The authors would like to thank the Swiss Federal Office of Energy (SFOE) for funding this
research through the Grant Agreement number SI/502336-01.
The first author would like to thanks the Colombian Administrative Department of Science,
Technology and Innovation (1128416066-646/2014). The second author acknowledges the
funding from the Ministry of Science, Innovation and Universities of Spain and the European
Union “Next Generation EU” through 2021-2023 Margarita Salas grant.
The third author acknowledges the Brazilian National Research Council for Scientific and
Technological Development CNPq (142148/2019-9), and the Swiss Government Excellence
Scholarship (2021.0235).
Acknowledgments
High
temperature
heat
pumps
integration
Florez-Orrego,
Daniel,
et
al.
25

26. Thanksforyourattention
Takfordinopmærksomhed
High
temperature
heat
pumps
integration
Florez-Orrego,
Daniel,
et
al.
26