1
. Introduction
Waste heat is defined as the residual heat after heat recovery within a process, heat recovery between several
processing units on a site, and residual heat rejected to cooling water and air from a site utility system. According to
IPCC (2010 data) Industry is responsible for 32% of worldwide greenhouse gas emissions, i.e. about 16 billion tonnes
of CO2 equivalent, including indirect emissions due to electricity used in industrial plants. According to the
International Energy Agency, energy/ waste heat recovery together with recycling is expected to bring 9% of the
necessary emissions reduction. Waste heat recovery (WHR) can significantly improve the site energy efficiency
which has been identified as the most cost-effective measure for carbon dioxide mitigation especially in the short and
medium term.
1
.1 Opportunities to achieve a more competitive, secure and sustainable energy system and to meet its long-
term 2050 greenhouse gas reductions target
a 40% cut in greenhouse gas emissions compared to 1990 levels;
at least a 32% share of renewable energy consumption, with an upward revisions clause for 2023;
indicative target for an improvement in energy efficiency at EU level of at least 32.5%, following on from
the existing 20% target for 2020.
In this context, efficient recovery of waste heat in the form of power, heat and chilling can contribute in three ways:
(
(
i)
ii)
supplying power and heat in the respective grid;
balancing the grid (both power and thermal) against the fluctuation caused by increased share of variable
renewables in the energy mix;
(
iii)
increasing energy efficiency and hence the energy security of waste heat generating site through saving
of primary energy.
1
.2 Barriers of WHR adoption
Although there are huge potential and numerous benefits of WHR, there are some barriers that impact the economy
and effectiveness of heat recovery equipment and impede its wider installation.
Barrier 1: Lack of justification: The lack of accurate evaluation of cost benefit of the WHR project does not build
confidence.
Barrier 2: Long payback period: Costs of heat recovery equipment, auxiliary systems, and design services lead to
long payback periods in certain applications.
Barrier 3: Composition of exhaust stream: Many exhaust streams are contaminated or containing fouling
particulates of some form. Resulting issues can be clogging and abrasion of devices, and corrosion or deposit
formation when temperatures are reduced below dew points of certain components when heat is extracted from a
stream. These aspects can limit the possibility to recover heat from some sources, or significantly increase the
associated costs.
Barrier 4: Economy of Scale: Equipment costs favour large-scale heat recovery systems and create challenges for
small-scale operations.
Barrier 5: Intermittent Character of waste heat source: This might cause fatigue in the heat exchange materials
due to thermal cycling. Moreover, the intermittent character of the recoverable energy flows and its variations during
normal operating conditions might not ensure energy efficient performance.
Barrier 6: Lack of awareness and initiatives: Industrial engineers often do not have the time or knowledge to
explore all waste heat recovery methods and are “unsure” or “uninformed” of the benefits of WHR. Novel methods
of WHR are often ignored due to lack of understanding.
Barrier 7: Lack of space: In some cases, spaces for installing WHR devices are very limited. This becomes more
complicated when additional energy storage needs to be installed while recovering waste heat from intermittent
sources.
Barrier 8: Expensive consultancy service: Expensive consultancy is required from start of potential WHR projects.
It demotivates WHR initiatives.
1
.3 Features of the tool
This tool is designed addressing the above stated barriers of WHR adoption. The main features of the tool are:
It will characterise waste heat stream i.e., the exhaust flue gas processing minimum numbers of user inputs;
It will provide dimensions of WHR devices such as heat pipe heat exchanger (HPHE) and thermal storages
for a specific WHR application;
It will provide stand alone solution where user will select the capacity of HPHE and the tool will give
different options for thermal energy storage;
It will provide multiple options of WHR solution depending on the flue gas temperature and the amount of
heat to be recovered;
It will provide informed investment decision support on the marginal investment (on WHR technology)
through evaluating (for each of the options for WHR solution) different financial parameters such as payback
period, net present value (NPV), internal rate of return (IRR), return on investment (ROI) etc.;
To account the uncertainty of different variables such as retrofitting factor, discount rate etc., it will perform
sensitivity analysis to determine the impact of these factors on payback period, NPV, IRR, ROI;
It will evaluate environmental performance for each of the options for WHR solution;
2
. Functional modules of the tool
There are five modules which are:
1
2
3
4
5
. Flue Gas Characterization
. Waste heat utilisation
. WHR solution
. Cost performance
. Environmental performance
User will provide data related to waste heat source through module 1 i.e., “flue Gas Characterization” module. Results
of module 1 and user data will be processed and fed to other modules to formulate different waste heat recovery
solutions along with the respective cost and environmental performances.
2
.1 Module 1- Flue Gas Characterization
Processing the user data, this module will predict the quality and quantity of the available waste heat and properties
of flue gas exiting the furnace. Using the temperature, flow measurement and the stream composition data, waste
heat stream will be characterised in terms of quantity and quality. For instance, if a waste heat stream contains ‘n’
th
1
number components, then the heat content in the I component can be expressed as:
1
Waste Heat Recovery: Technology and Opportunities in U.S. Industry; Prepared by BCS, Incorporated March 2008
th
i
Where h (t) is the enthalpy of the I species at the specified temperature T, r is the reference temperature (either
ambient temperature or the minimum allowed temperature of WHR), and Cp,I is the specific heat capacity of the
2
species as a function of temperature. Cp can be expressed as:
p
Where, T in Kelvin, C in kJ/kmol, K
After adding the enthalpies of all the constituents, the heat content of the waste stream will be determined. To
calculate the heat content of the flue gas, all the constituent gases (such as N
considered as ideal gas.
2
, H
2
, CO
2
, CO, SO
2
, H
2
O
(g) etc.) will be
Quantity
The key information of the results is outlined in the following table:
Item
Unit
Average density of flue gas (ambient to flue gas temperature)
Average density of flue gas (max allow temp of flue gas)
kg/m3
kg/m3
kW
Waste heat energy flow rate through the flue gas (w.r.t. ambient temperature)
Actual recoverable waste heat energy flow rate (w.r.t. maximum allowable temperature*) kW
Average specific heat capacity of flue gas (ambient to flue gas temperature)
Average specific heat capacity of flue gas (ambient to flue gas temperature)
kJ/kg.C
3
kJ/m .C
kJ/kg.C
Average specific heat capacity of flue gas (maximum allowable temperature* of the flue
gas to flue gas temperature)
Average specific heat capacity of flue gas (maximum allowable temperature* of the flue
gas to flue gas temperature)
3
kJ/m .C
*
Maximum allowable temperature of the flue gas = Acid dew point temperature + safety margin
The tool will offer three options to characterise flue gas. Based on the available information, user can select any of
the three options.
Option 1 (Flue Gas Characterization)
2
Source: B.G. Kyle, 1984, Chemical and Process Thermodynamics
Mandatory input (option 1)
3
1
2
3
4
5
6
. Natural gas (Fuel) flow rate, m /s
. O concentration in exhaust, %
. Flue gas temperature, C
. Furnace operating cycle
. Furnace ON time
2
o
. Furnace OFF time
Optional input (option 1)
1
2
3
4
. Natural gas composition
o
. Acid dew point temperature, C
o
. Ambient temperature, C
3
. Sp. Heat capacity of flue gas, kJ/m .C
Information flow diagram within option 1:
The logic and algorithm developed under the assumption of complete combustion. Other assumptions made under
option 1 of flue Gas Characterization (The corresponding values can be edited through admin panel) are listed in
the following table
Item
Unit Quantity Comments
o
o
Acid dew point temperature, C
Ambient temperature, C
Safety margin for acid dew point temperature, C
Pressure of the gaseous substance
C
C
C
150 If corresponding user input is null
20 If corresponding user input is null
20 Internal design variable
o
o
o
o
atm
1 Internal design variable
Option 2 (Flue Gas Characterization)
Mandatory input (option 2)
3
1
2
3
4
. Flue gas flow rate, m /s or kg/s
o
. Flue gas temperature, C
. Furnace operating cycle
. Flue gas composition, %vol or %mass
(
The default list of flue gas constituents)
Flue gas constituents
%Vol or %mass
N2
O2
CO
CO2
H2O
NO
N2O
NO2
SO2
SO3
C6H6
HCl
5
6
. Furnace ON time
. Furnace OFF time
Optional input (option 2)
o
. Acid dew point temperature, C
o
1
2
. Ambient temperature, C
Information flow diagram within option 2:
Assumptions made under option 2 of flue Gas Characterization (The corresponding values can be edited through
admin panel) are listed in the following table:
Item
Unit Quantity Comments
o
o
Acid dew point temperature, C
Ambient temperature, C
Safety margin for acid dew point temperature, C
Pressure of the gaseous substance
C
C
C
150 If corresponding user input is null
20 If corresponding user input is null
20 Internal design variable
o
o
o
o
atm
1 Internal design variable
Option 3 (Flue Gas Characterization)
2
.2. Module 2- Waste heat utilisation
andatory input (option 3)
3
1
2
3
. Natural gas (Fuel) flow rate, m /s
. Excess air, %
o
. Flue gas temperature, C
Optional input (option 3)
1
. Natural gas composition
Component (%Volume)
CH
4
C
2
C
3
C
4
H
H
H
6
8
10
CO
H
2
CO
2
N
2
O
2
H
2
H
2
S
O
o
2
3
. Acid dew point temperature, C
. Ambient temperature, C
o
Information flow diagram within option 3:
The logic and algorithm developed under the assumption of complete combustion. Other assumptions made under
option 3 of flue Gas Characterization (The corresponding values can be edited through admin panel) are listed in
the following table
Item
Natural gas composition
Unit
Quantity Comments
96%
CH
4
% vol
% vol
If corresponding user input is null
C
2
H
6
4%
o
o
Acid dew point temperature, C
C
C
C
150 If corresponding user input is null
20 If corresponding user input is null
20 Internal design variable
o
o
Ambient temperature, C
o
o
Safety margin for acid dew point temperature, C
Pressure of the gaseous substance
atm
1 Internal design variable
Module 2- Waste heat utilisation
(
This module will be developed in future)
To utilise the recovered waste, this module will incorporate six WHR technology options:
1
2
. Direct heat exchange via heat exchanger;
. Upgrading low grade heat through heat pump technologies
a. mechanical heat pump (MHP);
b. absorption heat pump (AHP);
c. absorption heat transformer (AHT);
3
4
. Absorption chiller (AbC) to produced chilled water;
. Rankine cycle (Organic Rankine cycle, ORC & steam Rankine cycle) to produce power.
This module will consider both onsite and offsite end use of recovered energy:
For onsite end use of recovered heat produced, whether directly via heat exchange or from heat upgrade
technologies, will be considered to be used for boiler feed water preheating, air preheating, space heating (within
the site), steam generation and hot utility reduction;
For onsite end use of recovered energy in the form of chilling will be considered to be used:
✓
to replace electrically driven vapour compression chillers (used for process and space cooling in the site) to
save electrical power; and
✓
to provide chilling to improve the power generation efficiency of a gas turbine, by reducing the compressor
inlet air temperature;
For onsite end use of recovered energy in the form of power will be considered to be used within the site to
reduce power import.
For offsite end use of recovered energy in the form heat, chilling and power will be considered to be exported to the
energy grid (such as power grid, central DHC network), neighbouring industries & local district heating and cooling
(
DHC) network, large private facilities such as shopping centre, sport centre, hospital, university etc.
2
.3. Module 3- WHR solution
In this module there are different submodules which includes:
Standalone solution
Cascaded solution
Component level solution
✓
✓
Heat Pipe Heat Exchanger (HPHE)
Thermal energy storage (TES)
Under the option of “Standalone solution”, user will select the capacity of HPHE, i.e., the amount of waste heat to
be recovered from the flue gas exiting the furnace. The tool will provide different options of TES along with overall
cost of the solution and dimensions of the core components of the solution.
Under the option of “Cascaded solution”, analysing the results of the flue gas characterisation module, tool will offer
multiple options of solution along with the overall cost of the solution, dimensions and cost of the core components
of the solution.
Under the option of “Component level solution”, the tool will provide cost and dimensions of the core components
of the solution.
The main components of WHR solution are
•
•
Heat Pipe Heat Exchanger (HPHE)
Dual Media Thermocline (DMT)
A HPHE is a liquid coupled indirect heat transfer type heat exchanger and employs a number of individually-sealed
or groups of sealed heat pipes or thermosyphons as the major heat transfer means from the high temperature to the
low temperature fluid. Thermosyphons are essentially heat pipes but without the wicking structure which uses gravity
to transfer heat from a heat source that is located below the cold sink. As a result, the evaporator section is situated
below the condenser section. The working fluid evaporates, condenses in the condenser section and flows back to
the evaporator section under the influence of gravity.
HPHE is a very good choice when a corrosive exhaust contains particulates or suspensions that could settle onto the
heat exchange surface. HPHEs are particularly suited to ‘difficult’ applications, for example because the construction
of the HPHE allows the heat pipe surfaces to be cleaned easily and quickly with very little system down-time. Water
will be the working fluid of the proposed HPHE.
Dual Media Thermocline (DMT): A thermocline tank uses a single tank to store thermal energy. Thermocline has
the potential to reduce the cost of the thermal storage system and it can dispatch thermal energy at nearly a constant
3
temperature over most of its discharge cycle . In a thermocline, isothermal hot and cold fluid regions become
separated by a narrow region of temperature gradient, which is called the thermocline or heat-exchange region. In a
dual-media thermocline (DMT) tank, a granulated material is added to the tank to reduce the amount of heat transfer
fluid (HTF) required to charge the system. In contrast, a single-medium thermocline (SMT) tank uses only HTF.
When the system is charged, cold fluid is drawn from the bottom, heated as it passes through a heat exchanger (heated
with the receiver heat transfer fluid) and returns to the top of the tank. When the tank is discharged, hot fluid is drawn
from the top and cooled as it passes through the end user heat sink (for example a heat exchanger to transfer heat for
steam generation) and returns to the bottom of the tank.
The proposed thermal energy storage is limited to 4 fluids
1
2
3
4
. Water,
. Therminol 66,
. HITEC salt,
. Solar Salt.
And the proposed thermal energy storage is limited to 3 solids
1
2
3
. Quartzite,
. Basalt,
. Quartz sand.
Component level solution
Mandatory input (For the analysis of TES)
1
2
3
4
. The minimal temperature of operation, ℃
. The maximal temperature of operation, ℃
. Charging power, kW
. DMT charging time, hour
3
Development of a molten-salt thermocline thermal storage system for parabolic trough plants- James E. Pacheco, Steven K. Showalter, William J. Kolb, Sandia
National Laboratories1, Solar Thermal Technology Department
Analysing the user data, the tool will provide storage solutions for different combination of HTF & storage material.
The key information that will be reported are given in the following table:
Item
Unit
m
Quantity
Bed Diameter
Bed Height
m
Tank height
m
Tank weight
tons
tons
tons
tons
M€
€/kWh
Fluid weight
Stone weight
Sand weight
DMT cost (installed, filled)
DMT specific cost
Assumptions made under the submodule of “thermal Storage Analysis” (The corresponding values can be edited
through admin panel) are listed in the following table:
Variables (when HTF is Water)
The year under consideration for analysis
Cost of water
Unit
year
Default value
2017
3
€/ton
€/ton
€/ton
€/ton
€/ton
€/ton
€/ton
number
m
Cost of thermal oil
7000
654
1753
122
278
452
2
Cost of Solar salt
Cost of hitec
Cost of Quartzite stones
Cost of Basalt stones
Cost of Sand
DMT height to diameter ratio
The maximum limit of DMT height
DMT height to diameter ratio
The maximum limit of DMT height
Safety margin for hot temperature
Factor to the fluid expansion
12
number
m
2
12
oC
20
number
3
Factor to the fluid expansion
number
m
3
0.003
2
Thickness margin for corrosion
Shape factor
number
number
m/s
Shape factor
2.5
2
the nominal velocity of HTF in pipes
Number of flowmeters to measure the flowrate of HTF to DMT
Number of PT100 probes at the inlet and outlet of the DMT
Number of pressure sensors at the top and at the bottom of the DMT
Number of level sensor if the DMT contains a gas sky
Number of thermocouples along a vertical axis
Number of thermocouples along 2 radius
Number of pressostat (for pressure safety)
Number of thermostat (for temperature safety)
Unit cost of flowmeter
number
number
number
number
number
number
number
number
€/unit
2
2
2
1
10
10
1
1
5000
500
1500
1500
100
500
500
100
2
Unit cost of PT100 probes
€/unit
Unit cost of pressure sensors
€/unit
Unit cost of level sensor
€/unit
Unit cost of thermocouples
€/unit
Unit cost of pressostat
€/unit
Unit cost of thermostat
€/unit
The connection cost
€/line
Number of analog card required
number
€/unit
Cost of analog card
500
700
7
Cost per day per person for control software modification and final tests
€/day/person
number
Number of person-day required for control software modification & final
tests
Cost per km for fuel and toll
€/km
€/day
€/hour
km
0.485
165.98
22.43
500
The cost per day (for truck + structure costs)
The cost per hour (for driver)
The average distance of the transport of solid filler
Distance travelled by truck per day
km/day
500
Variables (when HTF is Thermal oil)
The year under consideration for analysis
Cost of water
Unit
year
Default value
2017
3
€/ton
€/ton
€/ton
€/ton
€/ton
€/ton
€/ton
number
m
Cost of thermal oil
7000
654
1753
122
278
452
2
Cost of Solar salt
Cost of hitec
Cost of Quartzite stones
Cost of Basalt stones
Cost of Sand
DMT height to diameter ratio
The maximum limit of DMT height
DMT height to diameter ratio
The maximum limit of DMT height
Safety margin for hot temperature
Factor to the fluid expansion
Factor to the fluid expansion
Thickness margin for corrosion
12
number
m
2
12
oC
20
number
number
m
3
3
0.003
Shape factor
number
m/s
2.5
2
The nominal velocity of HTF in pipes
Number of flowmeters to measure the flowrate of HTF to DMT
Number of PT100 probes at the inlet and outlet of the DMT
Number of pressure sensors at the top and at the bottom of the DMT
Number of level sensor if the DMT contains a gas sky
Number of thermocouples along a vertical axis
Number of thermocouples along 2 radius
Number of pressostat (for pressure safety)
Number of thermostat (for temperature safety)
Unit cost of flowmeter
number
number
number
number
number
number
number
number
€/unit
2
2
2
1
10
10
1
1
5000
500
1500
1500
100
500
500
100
2
Unit cost of PT100 probes
€/unit
Unit cost of pressure sensors
€/unit
Unit cost of level sensor
€/unit
Unit cost of thermocouples
€/unit
Unit cost of pressostat
€/unit
Unit cost of thermostat
€/unit
The connection cost
€/line
Number of analog card required
number
€/unit
Cost of analog card
500
700
7
Cost per day per person for control software modification and final tests
€/day/person
Number of person-day required for control software modification and final tests number
Cost per km for fuel and toll
€/km
€/day
€/hour
km
0.485
165.98
22.43
500
500
1050
680
50
The cost per day (for truck + structure costs)
The cost per hour (for driver)
The average distance of the transport of solid filler
Distance travelled by truck per day
km/day
km
The average distance of the transport of HTF (except water)
The cost of a mobile lift crane (30 ton) on truck with driver
The cost of labour per hour
€/day
€/hour
Variables (when HTF is Hitec)
The year under consideration for analysis
Cost of water
Unit
year
Default value
2017
3
€/ton
€/ton
€/ton
€/ton
€/ton
€/ton
€/ton
number
m
Cost of thermal oil
7000
654
1753
122
278
452
2
Cost of Solar salt
Cost of hitec
Cost of Quartzite stones
Cost of Basalt stones
Cost of Sand
DMT height to diameter ratio
The maximum limit of DMT height
DMT height to diameter ratio
The maximum limit of DMT height
Safety margin for hot temperature
Factor to the fluid expansion
Thickness margin for corrosion
Shape factor
12
number
m
2
12
oC
20
number
m
3
0.003
2.5
number
Shape factor
number
m/s
2.5
2
the nominal velocity of HTF in pipes
Number of flowmeters to measure the flowrate of HTF to DMT
Number of PT100 probes at the inlet and outlet of the DMT
Number of pressure sensors at the top and at the bottom of the DMT
Number of level sensor if the DMT contains a gas sky
Number of thermocouples along a vertical axis
Number of thermocouples along 2 radius
Number of pressostat (for pressure safety)
Number of thermostat (for temperature safety)
Unit cost of flowmeter
number
number
number
number
number
number
number
number
€/unit
2
2
2
1
10
10
1
1
5000
500
1500
1500
100
500
500
100
2
Unit cost of PT100 probes
€/unit
Unit cost of pressure sensors
€/unit
Unit cost of level sensor
€/unit
Unit cost of thermocouples
€/unit
Unit cost of pressostat
€/unit
Unit cost of thermostat
€/unit
The connection cost
€/line
Number of analog card required
number
€/unit
Cost of analog card
500
700
7
Cost per day per person for control software modification and final tests
€/day/person
Number of person-day required for control software modification and final tests number
Cost per km for fuel and toll
€/km
€/day
€/hour
km
0.485
165.98
22.43
500
500
1050
680
50
The cost per day (for truck + structure costs)
The cost per hour (for driver)
The average distance of the transport of solid filler
Distance travelled by truck per day
The average distance of the transport of HTF (except water)
The cost of a mobile lift crane (30 ton) on truck with driver
The cost of labour per hour
km/day
km
€/day
€/hour
kW
Electric oven capacity
400
30,000
10000
3000
10000
Rental charge of oven for first week
Rental charge of oven for other week
Rental cost of diesel generator
€/week
€/week
€/week
€
Cost of auxiliary components
Variables (when HTF is Molten salt)
The year under consideration for analysis
Cost of Quartzite stones
Unit
year
Default value
2017
122
278
452
2
€/ton
€/ton
€/ton
Cost of Basalt stones
Cost of Sand
DMT height to diameter ratio
The maximum limit of DMT height
DMT height to diameter ratio
The maximum limit of DMT height
Safety margin for hot temperature
Unit cost of flowmeter
number
m
12
number
2
m
oC
12
20
€/unit
€/unit
5000
500
Unit cost of PT100 probes
Unit cost of pressure sensors
Unit cost of level sensor
€/unit
€/unit
€/unit
€/unit
€/unit
€/unit
€
1500
1500
100
Unit cost of thermocouples
Unit cost of pressostat
500
Unit cost of thermostat
500
Cost of analog card
500
Total cost of analog card
1000
4900
680
Total cost for control software modification and final tests
The cost of a mobile lift crane (30 ton) on truck with driver
The cost of labour per hour
€
€/day
€/hour
kW
50
Electric oven capacity
400
Rental charge of oven for first week
Rental charge of oven for other week
Rental cost of diesel generator
Cost of auxiliary components
€/week
€/week
€/week
€
30,000
10000
3000
10000
Mandatory input (For the analysis of HPHE)
1
2
3
. HPHE capacity, kW
. Cold side inlet temperature, C
. Cold side exit temperature, C
o
o
Analysing the user data, the tool will provide details of HPHE solutions. The key information that will be reported
are given in the following table:
Item
Unit
kg
Amount used
Unit cost, € Cost, €
Carbon steel
3
04 stainless steel
kg
Distilled water
kg
Aluminium paint
litre
Direct material cost
Manufacture, assemble pipes
Direct labour
number
labour-day
kwh
Electrical energy
Transportation of material to HPHE manufacturing plant tkm
Transportation of HPHE to site
Direct transportation cost
Total variable cost, €/unit
Manufacturing overhead over variable cost
Profit margin over variable cost
Total cost of HPHE, €
tkm
Specific cost of HPHE, €/kw
Dimension
Length
meter
Width
meter
meter
m3
Height
Volume
Assumptions made under the submodule of “HPHE Analysis” (The corresponding values can be edited through
admin panel) are listed in the following table:
Variables
Unit
Default value
20
o
Safety margin for acid dew point temperature, C
C
Length of each pipe, meter
meter
meter
meter
%
1.57
0.04
0.002
5%
Diameter of HPHE pipe, meter
HPHE pipe wall thickness, meter
Adiabatic section, %
Maximum capacity of HPHE, kw
Minimum capacity of HPHE, kw
HPHE working fluid filling rate, %
kw
800
50
kw
%
60%
10
o
Minimum temperature difference for heat transfer to cold stream, C
Minimum clearance from side wall to pipe, meter
Longitudinal pitch factor with respect to pipe diameter, number
Transverse pitch factor with respect to pipe diameter, number
Thickness of side plates of HPHE, meter
Thickness of separator plate of HPHE, meter
Mass multiplication factor for HPHE, number
Cost of carbon steel, €/kg
C
meter
number
number
meter
meter
number
€/kg
0.02
1.8
1.8
0.005
0.005
1.30
0.8
Cost of SS304, €/kg
€/kg
2.9
Cost of manufacturing each heat pipe, €/piece
Cost of distilled water, €/kg
€/piece
€/kg
10
1.6
Direct labour- HPHE capacity curve slope, number
Labour rate, €/ Labour-day
number
€/ Labour-day
number
€/kwh
micron
%
0.08
140
2.75
0.03
25
Electricity consumption factor with respect to HPHE capacity, number
Electrical energy price, €/kwh
Paint thickness for HPHE side plates, micron
paint efficiency, %
80%
35
Cost of paint, €/litre
€/litre
€/tkm
km
Transportation cost rate for material supply to HPHE plant, €/tkm
Average transport distance for HPHE material supply, km
Transportation cost rate to deliver HPHE to site, €/tkm
Average transport distance of HPHE to site, km
1.8
200
3.2
€/tkm
km
500
0.1
Manufacturing overhead factor with respect to variable cost for HPHE, number number
Profit factor over variable cost of HPHE, number number
0.3
For both stand alone and cascaded solution the maximum and minimum capacity of HPHE are considered to be 800
kW and 50 kW respectively. The maximum capacity of TES is around 6.4 MWh.
If the waste heat flow rate is greater than 800 kW, then two HPHEs can be used in parallel to recover waste heat from
the flue gas exiting the furnace. If there are sufficient waste heat left after the first stage of heat recovery, then a
secondary stage of heat recovery application can be deployed. As the source of waste heat is of intermittent in nature,
each of the stages will have a combination of HPHE and TES, hence, two loops will be formed- one is primary loop
and the other is secondary loop where the primary loop will be operated at relatively higher temperature (i.e., T_hot
&
T_cold).
Figure: Schematic diagram of cascaded solution
o
o
For a situation, 350 C<= Flue gas temperature =< 700 C, there will be total 32 number of possible solutions.
o
o
For a situation, 200 C<= Flue gas temperature < 350 C, there will be total 12 number of possible solutions
Summary of the cascaded solutions are outlined in the following table:
Primary loop
Secondary loop
SL
No. Solution HPHE 1 HPHE 2 DMT
T_hot T_cold
DMT
T_hot T_cold
1
2
3
4
5
6
7
8
9
111a
111b
111c
111d
112a
112b
112c
112d
121a
HPHE 1 HPHE 2 Hitec + Quartzite
300
300
300
300
300
300
300
300
300
300
170 HPHE 3 Thermal oil + Quartzite
170 HPHE 3 Thermal oil + Quartzite
150
150
80
80
80
80
40
40
40
40
80
80
80
80
40
40
40
40
80
80
80
80
40
40
40
40
HPHE 1 HPHE 2 Hitec + Quartzite + Sand
HPHE 1 HPHE 2 Hitec + Quartzite
170 HPHE 3 Thermal oil + Quartzite + Sand 150
170 HPHE 3 Thermal oil + Quartzite + Sand 150
HPHE 1 HPHE 2 Hitec + Quartzite + Sand
HPHE 1 HPHE 2 Hitec + Quartzite
170 HPHE 3 Water (SMT)
90
90
HPHE 1 HPHE 2 Hitec + Quartzite
170 HPHE 3 Water + Quartzite
170 HPHE 3 Water (SMT)
HPHE 1 HPHE 2 Hitec + Quartzite + Sand
HPHE 1 HPHE 2 Hitec + Quartzite + Sand
HPHE 1 HPHE 2 Thermal oil + Quartzite
HPHE 1 HPHE 2 Thermal oil + Quartzite
90
170 HPHE 3 Water + Quartzite
170 HPHE 3 Thermal oil + Quartzite
90
150
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
0 121b
1 121c
2 121d
3 122a
4 122b
5 122c
6 122d
7 131a
8 131b
9 131c
0 131d
1 132a
2 132b
3 132c
4 132d
170 HPHE 3 Thermal oil + Quartzite + Sand 150
170 HPHE 3 Thermal oil + Quartzite 150
170 HPHE 3 Thermal oil + Quartzite + Sand 150
HPHE 1 HPHE 2 Thermal oil + Quartzite + Sand 300
HPHE 1 HPHE 2 Thermal oil + Quartzite + Sand 300
HPHE 1 HPHE 2 Thermal oil + Quartzite
HPHE 1 HPHE 2 Thermal oil + Quartzite
300
300
170 HPHE 3 Water (SMT)
90
90
170 HPHE 3 Water + Quartzite
170 HPHE 3 Water (SMT)
HPHE 1 HPHE 2 Thermal oil + Quartzite + Sand 300
HPHE 1 HPHE 2 Thermal oil + Quartzite + Sand 300
90
170 HPHE 3 Water + Quartzite
170 HPHE 2 Thermal oil + Quartzite
170 HPHE 2 Thermal oil + Quartzite
90
HPHE 1
HPHE 1
HPHE 1
HPHE 1
HPHE 1
HPHE 1
HPHE 1
HPHE 1
Hitec + Quartzite
300
300
300
300
300
300
300
300
150
150
Hitec + Quartzite + Sand
Hitec + Quartzite
170 HPHE 2 Thermal oil + Quartzite + Sand 150
170 HPHE 2 Thermal oil + Quartzite + Sand 150
Hitec + Quartzite + Sand
Hitec + Quartzite
170 HPHE 2 Water (SMT)
170 HPHE 2 Water + Quartzite
170 HPHE 2 Water (SMT)
170 HPHE 2 Water + Quartzite
90
90
90
90
Hitec + Quartzite
Hitec + Quartzite + Sand
Hitec + Quartzite + Sand
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
5 133a
6 133a
7 133a
8 133a
9 134a
0 134b
1 134c
2 134d
3 211a
4 211b
5 211c
6 211d
7 221a
8 221b
9 221c
0 221d
1 23a
HPHE 1
HPHE 1
HPHE 1
HPHE 1
HPHE 1
HPHE 1
HPHE 1
HPHE 1
Thermal oil + Quartzite
Thermal oil + Quartzite
300
300
170 HPHE 2 Thermal oil + Quartzite
170 HPHE 2 Thermal oil + Quartzite + Sand 150
170 HPHE 2 Thermal oil + Quartzite 150
170 HPHE 2 Thermal oil + Quartzite + Sand 150
150
80
80
80
80
40
40
40
40
30
30
30
30
30
30
30
30
Thermal oil + Quartzite + Sand 300
Thermal oil + Quartzite + Sand 300
Thermal oil + Quartzite
Thermal oil + Quartzite
300
300
170 HPHE 2 Water (SMT)
170 HPHE 2 Water + Quartzite
170 HPHE 2 Water (SMT)
170 HPHE 2 Water + Quartzite
80 HPHE 3 Water (SMT)
80 HPHE 3 Water (SMT)
80 HPHE 3 Water + Quartzite
80 HPHE 3 Water + Quartzite
80 HPHE 2 Water (SMT)
80 HPHE 2 Water (SMT)
80 HPHE 2 Water + Quartzite
80 HPHE 2 Water + Quartzite
40
90
90
90
90
80
80
80
80
80
80
80
80
Thermal oil + Quartzite + Sand 300
Thermal oil + Quartzite + Sand 300
HPHE 1 HPHE 2 Thermal oil + Quartzite
HPHE 1 HPHE 2 Thermal oil + Quartzite + Sand 150
HPHE 1 HPHE 2 Thermal oil + Quartzite 150
HPHE 1 HPHE 2 Thermal oil + Quartzite + Sand 150
150
HPHE 1
HPHE 1
HPHE 1
HPHE 1
Thermal oil + Quartzite 150
Thermal oil + Quartzite + Sand 150
Thermal oil + Quartzite 150
Thermal oil + Quartzite + Sand 150
HPHE 1 HPHE 2 Water (SMT)
90
90
90
90
2 23b
HPHE 1 HPHE 2 Water + Quartzite
40
3 24a
HPHE 1
HPHE 1
Water (SMT)
40
4 24b
Water + Quartzite
40
According to specific cost of WHR solution, the solutions will be ranked for a specific scenario of waste heat quality
and quantity.
2
.4. Module 4- Financial performance
For each of the WHR solution identified by module 3, the tool will provide informed investment decision support on
the marginal investment (on WHR technology) through evaluating following financial parameters:
1
2
3
4
5
t
. Levelised cost of thermal energy (LCOE ),
. Payback period,
. Net present value (NPV),
. Internal rate of return (IRR),
. Return on investment (ROI) etc.
To account the uncertainty of different variables such as retrofitting factor, discount rate etc., the tool will perform
sensitivity analysis to determine the impact of these factors on LCOE , payback period, NPV, IRR, ROI;
t
Assumptions made under the module 4 (The corresponding values can be edited through admin panel) are listed in
the following table:
Variables
Unit
Default value
Plant downtime
%
10%
24
Daily operation hours
Discount rate
hour/day
%
5%
20
Service life
Year
Retrofitting factor
number
€/kWh
%
1
Natural gas price
0.0313
10%
4
Installation & commission cost with respect to capex
Number of times of HTF preheating operation per year
Cost of electricity
number
€/kWh
€/hour
0.07
50
The cost of labour per hour
2
.5. Module 5- Environmental performance
For each of the WHR solution identified by module 3, the tool will provide the information regarding the resource
and energy consumed during the respective manufacturing and use phases. The key information regarding resource
consumption that will be available is illustrated in the following table
Amount
Resources
For HPHE
Carbon steel, kg
3
04 stainless steel, kg
Distilled water, kg
Aluminium paint, litre
For TES
Carbon steel, kg
3
04 stainless steel, kg
HTF, kg
Quartzite, kg
Sand, kg
For piping & instrumentation
Carbon steel, kg
3
04 stainless steel, kg
HTF, kg
Finally, for each of the WHR solution identified by module 3, the tool will provide the potential emission saving
opportunities created by the application of the respective WHR solution.