Part 6 Synthesis of Heat Exchanger Networks 6
- Slides: 54
Part 6 Synthesis of Heat Exchanger Networks
6. 1 Sequential Synthesis Minimum Utility Cost
Example 1 Fcp (MW/C) Tin (C) Tout (C) H 1 1 400 120 H 2 2 340 120 C 1 1. 5 160 400 C 2 1. 3 100 250 Steam: 500 C Cooling water: 20 – 30 C Minimum recovery approach temperature (HRAT): 20 C
Heat Balances around Temperature Intervals
Transshipment Model
Remarks • LP for minimum utility consumption leads to the same results as the Problem Table in Pinch method. • The transshipment model can be generalized to consider multiple utilities to minimize total utility cost. • This model can be expanded so as to handle constraints on matches. • This model can also be expanded so as to predict the matches for minimizing the number of units. • We can embed the equations of the transshipment model within an optimization model for synthesizing a process system where the flows of the process streams are unknown.
Index Sets
Condensed Transshipment Model
Example 2 H 1 FCp (MW/K) 2. 5 Tin (K) 400 Tout (K) 320 H 2 3. 8 370 320 C 1 2. 0 300 420 C 2 2. 0 300 370 HP Steam: 500 K, $80/k. W-yr LP Steam: 380 K, $50/k. W-yr Cooling Water: 300 K, $20/k. W-yr HRAT: 10 K
Sequential Synthesis Minimum Utility Cost with Constrained Matches
Basic Ideas
Heat Exchange Options • Hot stream i and cold stream j are present in interval k (see figure in the previous page). • Cold stream j is present in interval k, but hot stream i is only present at higher temperature interval (see figure in the next page).
Index Sets
Expanded Transshipment Model
Match Constraints
Example 1 Fcp (MW/C) Tin (C) Tout (C) H 1 1 400 120 H 2 2 340 120 C 1 1. 5 160 400 C 2 1. 3 100 250 Steam: 500 C, $80/k. W-yr Cooling water: 20 – 30 C, $20/k. W-yr Minimum recovery approach temperature (HRAT): 20 C The match between H 1 and C 1 is forbidden.
Condensed Transshipment Model The annual utility cost: $9, 300, 000.
Expanded Transshipment Model Annual Utility Cost: $15, 300, 000 Heating Utility Load: 120 MW Cooling Utility Load: 285 MW
Sequential Synthesis Prediction of matches for minimizing the unit number
Objective Function
Heat Balances The constraints in the expanded transshipment model can be modified for the present model: 1. The heat contents of the utility streams are given. 2. The common index i can be used for hot process and utility streams; The common index j can be used for cold process and utility streams.
Heat Balances
Logical Constraints
Solution
Example 1 Fcp (MW/C) Tin (C) Tout (C) H 1 1 400 120 H 2 2 340 120 C 1 1. 5 160 400 C 2 1. 3 100 250 Steam: 500 C Cooling water: 20 – 30 C Minimum recovery approach temperature (HRAT): 20 C
Condensed Transshipment Model
MILP (i)
MILP (ii)
Solution
Alternative Solution
Solve MILP without Partition
Only 5 units! One less than the previous two!
Sequential Synthesis Automatic Generation of Network Structures
Basic Ideas • Each exchanger in the superstructure corresponds to a match predicted by the MILP model (with or without pinch partition). Each exchanger will also have as heat load the one predicted by MILP. • The superstructure will contain those stream interconnections among the units that can potentially define all configurations. The stream interconnections will be treated as unknowns that must be determined.
Superstructure for one hot stream and two cold streams
Embedded Alternative Configurations • • H 1 -C 1 and H 1 -C 2 in series H 1 -C 2 and H 1 -C 1 in series H 1 -C 1 and H 1 -C 2 in parallel with bypass to H 1 -C 2 • H 1 -C 1 and H 1 -C 2 in parallel with bypass to H 1 -C 1
Parameters and Unknowns
Objective Function
Equality Constraints
Inequality Constraints
Example 3 Stream Tin (K) Tout (K) Fcp (k. W/K) h (k. W/m^2 K ) Cost ($/k. W-yr) H 1 440 350 22 2. 0 - C 1 349 430 20 2. 0 - C 2 320 368 7. 5 0. 67 - S 1 500 - 1. 0 120 W 1 300 320 - 1. 0 20 Minimum temperature approach = 1 K Exchanger cost = 6600+670(Area)^0. 83
Solution
- Heat exchanger network synthesis
- Virtual circuit network and datagram network
- Basestore iptv
- Compabloc plate heat exchanger
- Parallel heat exchanger
- Twisted tube heat exchanger
- We
- Pipe in pipe heat exchanger
- Bell delaware method
- Sieder tate equation
- Counter flow heat exchanger
- What is the general range of ntu in heat exchanger design
- Hazop analysis for separator
- Heat exchanger test ring drawing
- Extended surface heat exchanger
- Lmtd heat exchanger formula
- Pipe
- Discharge pipe thermistor
- Shell and tube heat exchanger cost estimation
- In shell and tube surface condenser
- Regenerative type heat exchanger
- 2-4 shell and tube heat exchanger design
- Wood boiler heat exchanger
- Cracked heat exchanger
- Heat definition
- The controllers chapter 8
- Parker heat exchanger
- Plate type exchanger
- Water exchanger
- Structure of vascular cambium
- Shell and tube type condenser
- Rusty heat exchanger
- Standard xchange heat exchanger
- A shell and tube heat exchanger
- Simple heat exchanger
- Shell and tube type
- Concentric double pipe heat exchanger
- Viessmann heat exchanger
- Tubesheet heat exchanger
- Cross counter flow heat exchanger
- Simple heat exchanger
- Sanitary plate heat exchanger
- Propane heat exchanger
- Rheem solaraide price
- Refrigeration system design
- Reactor heat exchanger
- Rusty heat exchanger
- Single pass heat exchanger
- A double pipe parallel flow heat exchanger
- Shell and tube heat exchanger in food industry
- A double pipe parallel flow heat exchanger
- Counter flow heat exchanger
- A double pipe parallel flow heat exchanger
- Pool heat exchanger for boiler
- Subsoil heat exchanger