2012 Spring Meeting & 8th Global Congress on Process Safety
(52a) Practical Process Integration Retrofit Part 1. Cross-Pinch Method
Author
Practical Process Integration Retrofit
Part 1. Cross-Pinch Method
G.T.Polley
A number of techniques have
been developed to aid the process engineer retrofit heat recovery networks. The
first of these methods was called the ?Cross-Pinch Method? (Tjoe & Linnhoff
[1986]) and whilst it is widely practised by specialist consultants it has not,
to the author's knowledge, ever been formally described.
The first step in applying
the cross-pinch method is the identification of a heat recovery target. This is
achieved using an approximate economic analysis that seeks to relate project
savings with capital investment.
Economics of Network Retrofit
Economic Criteria for
Energy Saving Retrofit
Relationship Between
Installed Area and Energy Consumption
Relating Energy
Saving to Project Economics
Full Cost
Considerations
Starting Point for
Cross-Pinch Method
Example Problem
Cross-Pinch Design
Method
|
|
|
Below |
Pinch |
|
Above |
Pinch |
|
|
Stream |
Cp |
Low Temp. |
High Temp. |
Load |
Low Temp. |
High Temp. |
Load |
|
E1 (hot) |
0.1 |
|
|
|
174 |
327 |
15.3 |
|
E1 (cold) |
0.1 |
100 |
140 |
4.0 |
140 |
253 |
11.3 |
|
E2 (hot) |
0.16 |
160 |
161 |
0.16 |
161 |
220 |
9.44 |
|
E2 (cold) |
0.2 |
|
|
|
140 |
188 |
9.6 |
|
E3 (hot) |
0.2 |
121 |
160 |
7.8 |
|
|
|
|
E3 (cold) |
0.175 |
80 |
125 |
7.9 |
|
|
|
|
E4 (hot) |
0.06 |
110 |
161 |
3.06 |
161 |
220 |
3.54 |
|
E4 (cold) |
0.06 |
60 |
140 |
4.8 |
140 |
170 |
1.80 |
|
E5 (hot) |
0.1 |
84 |
161 |
7.7 |
161 |
174 |
1.3 |
|
E5 (cold) |
0.07 |
35 |
140 |
7.35 |
140 |
164 |
1.68 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Table 3. Pinch Table
References
Tjoe T.N. & Linnhoff B.
?Using pinch technology for process retrofit?, Chem.Engng., 1986 April 28,
pp47-60
Ahmad S. & Linnhoff B.
?Supertargeting: Different process structures for different economics?, ASME
J.En.Res.Tech., 1989, 111(3), 131-136
Tjoe T.N. Ph.D. Thesis 1986,
UMIST, UK