Heat/Energy
Integration
Process Integration
Process Energy Optimization
What is Process Integration?
What do we mean by a Process?
What do we mean by Integration?
A Process can be regarded as a
“Converter”
Process Integration
ØIntegration means combining Needs/Tasks of
“opposite”
kinds so that Savings can be obtained
ØExamples of such Integration in the Process
Industries:
♦ Heat Integration
♦ Power Integration
♦ Chemical Integration
♦ Equipment Integration → Process Intensification
Process Development & Optimization
Avoid
Reduce
Recover
Improve utility supply
Site heat &
Power systems
Utilities
Heat
Exchanger
network
Heat Recovery
Separation
Process
Development
Reaction
Chemical
synthesis
Case study
Title
•“Heat integration analysis
for an industrial ethyl
benzene plant using pinch
analysis” by Sung-Geun
Yoon et al. (2007)
Description
•HEN was retrofitted by
pinch analysis to save
energy.
•Alternative HEN is
achieved by adding new
heat exchanger &
changing operating
conditions.
Results
•It reduces the annual
energy cost by 5.6%
•In order to achieve it,
capital investment is
necessary
•But the annual cost
saving will be enough to
recover the cost in less
than one year
Case study
Title
•“Reducing Hot & Cold
Utility Requirements for
Finishing Column section
using Pinch Analysis
Techniques” by Deepa &
Ravishankar (2013)
Description
Results
•The process flow diagram •The utilities available
of finishing column section within the process can be
was received from a
used better
chemical industry
•Hot & Cold streams were •Energy can be conserved
identified & pinch analysis to an extent of 23%
was done to find minimum
Heating & Cooling utility
requirement
Applications of Process Integration
§ Heat integration-HEN
§ Mass exchange network-MEN
§ Distillation column targeting
§ Cogeneration
§ Debottlenecking of critical areas in process
industries
§ Emission targeting
§ Low temperature process
§ Financial management
Heat Integration
ØTypical energy saving 15 – 45 %
ØVery general – easily applicable in Power
generation, Oil refining, Petrochemicals, Food and
Drink Industry, Pulp & Paper, hospitals etc.
Synthesis of HENs
Possible two-stage method to the
synthesis of HEN
Pinch Technology/Pinch Analysis
T1
C
T2
o
§ Principal objective
§ Pinch Analysis
§ The change in enthalpy rate for each
steam is obtained by
∆H=mCp∆T=CP ∆T
§ The optimum exchanger size exists
where the total annualized cost is
minimized
§ This typically will correspond to a
minimum approach temperature, ∆Tmin
of about 10oC
§ This ∆Tmin=10oC is a rule of thumb – it
can change depending on the fluid
service and the type of heat exchanger
employed
t1
t2
Minimum approach
temperature
Pinch Technology/Pinch Analysis
1. Pinch technology is a methodology for optimizing energy usage in industrial processes.
2. It involves analyzing energy flows in a process and identifying points where heat can be recovered and
reused.
3. The principles of pinch technology are based on the second law of thermodynamics.
4. Pinch technology involves the use of process integration techniques to minimize the use of external
utilities.
5. Pinch analysis can be used to identify heat recovery opportunities in various industrial processes.
6. The chemical industry can benefit from pinch technology by optimizing the design of process plants.
7. Pinch analysis can be used in distillation, reaction, and heat exchange processes.
8. The food industry can benefit from pinch technology by optimizing the design of food processing
plants.
9. Pinch analysis can help to identify opportunities for heat recovery and reuse in food processing
operations.
10. Pinch technology can significantly reduce energy consumption and costs in industrial processes.
Pinch Technology/Pinch Analysis
11. It can help companies to achieve their sustainability goals and reduce their environmental impact.
12. Pinch technology can help companies comply with regulatory requirements related to energy efficiency
and environmental sustainability.
13. Pinch technology has a wide range of applications in various industrial sectors.
14. It can help to reduce greenhouse gas emissions and other environmental impacts.
15. Pinch technology can improve the efficiency and profitability of industrial processes.
16. It can help companies to optimize their use of energy resources.
17. Pinch technology is based on the calculation of heat balances and the identification of pinch points.
18. Pinch technology has been successfully applied in various industrial sectors, including chemical,
petrochemical, and food industries.
19. The benefits of pinch technology include cost savings, environmental sustainability, and compliance
with regulatory requirements.
20. Pinch technology is likely to become more widespread as the demand for energy-efficient technologies
continues to grow.
Pinch Analysis
1.Temperature Interval Method
2.Composite Curve Method (Graphical)
3.Linear Programming
Temperature Interval
Method
Pinch Analysis: Temperature Interval
Method
Step 1: Adjust hot stream temperatures by subtracting ΔTmin
(This puts the streams in a common reference frame.)
Pinch Analysis: Temperature Interval
Method
Step 2: Order the temperatures hot to cold:
250 : T0
240 : T1
235 : T2
180 : T3
150 : T4
120 : T5
Pinch Analysis: Temperature Interval Method
Step 3: For each temperature range (hot to next hottest),
determine which streams are in that interval and add
up the heat capacity rates of those streams
250
240
150
120
1.5
18
Pinch Analysis: Temperature Interval
Method
Step 3: For each temperature range (hot to next hottest),
determine which streams are in that interval and add up the heat
capacity rates of those streams
250 – 240: H1
240 – 235: H1, H2, C2
235 – 180: H1, H2, C1, C2
180 – 150: H1, H2, C1
150 – 120: H2, C1
19
Pinch Analysis: Temperature Interval
Method
Step 4: Multiply the combined heat capacity rate by the
temperature difference to get the energy needed to
cool or heat over that temperature range
250 : T0
240 : T1
235 : T2
180 : T3
150 : T4
120 : T5
20
Pinch Analysis: Temperature Interval
Method
Step 5: Create a cascade of temperature
intervals within which energy balances
are carried out
Pinch point
Note!
Energy can not flow from cold to hot. Thus,
we need to increase all of the levels by 50 to
make the pinch point = zero.
Pinch Analysis: Temperature Interval
Method
Pinch Analysis
Actual Endpoint Temperatures!
Hot side
One HEN
ΔTapp
Cold side
One HEN
Composite curve prepared for
pinch technology analysis
§ Do not transfer heat across the Pinch
point
§ Do not use a Hot utility below the Pinch
point
§ Do not use a Cold utility above the Pinch
point
§ Approach temperature should not be
less than specified ∆Tmin
Pinch technology Guidelines
Block Diagram of
Finishing Column
Initial Heating Utility
Requirement=6,500 kW
Initial Cooling Utility
Requirement=14,300 kW
Hot Stream Data
Cold Stream Data
Representation of Hot Streams
Representation of Cold Streams
Thermal Pinch Diagram