Abstract
Process cogeneration is an effective strategy for exploiting the positive aspects of combined heat and power in the process industry. Traditionally, decisions for process cogeneration have been based mostly on economic criteria. With the growing interest in sustainability issues, there is need to consider economic, environmental, and social aspects of cogeneration. The objective of this article is to develop an optimization framework for the design of process cogeneration systems with economic, environmental, and social aspects. Process integration is used as the coordinating framework for the optimization formulation. First, heat integration is carried out to identify the heating utility requirements. Then, a multi-header steam system is designed and optimized for inlet steam characteristics and their impact on power, fixed and operating costs, greenhouse gas emissions, and jobs. A genetic algorithm is developed to solve the optimization problem. Multi-objective tradeoffs between the economic, environmental, and social aspects are studied through Pareto tradeoffs. A case study is solved to illustrate the applicability of the proposed procedure.
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Abbreviations
- A :
-
Constant for the turbine efficiency relationship
- a 0 :
-
Constant for the turbine efficiency
- a 1 :
-
Constant for the turbine efficiency
- a 2 :
-
Constant for the turbine efficiency
- a 3 :
-
Constant for the turbine efficiency
- a e :
-
Electrical power price
- a f :
-
Unit fuel cost for fuel f
- A s :
-
Constant for the saturation temperature correlation
- B :
-
Constant for the turbine efficiency relationship
- B s :
-
Constant for the saturation temperature correlation
- C boiler :
-
Cost for the boiler
- Costa :
-
Combustion air fan power cost
- Costb :
-
Sewer charges for boiler blowdown
- Costd :
-
Ash disposal cost
- Coste :
-
Environmental emissions control cost
- CostBFW :
-
Boiler feed water treatment cost
- Costfuel :
-
Fuel cost
- Costg :
-
Generation cost
- Costm :
-
Maintenance materials and labor cost
- Costp :
-
Feed water pumping power cost
- Costw :
-
Raw water supply cost
- C Turbine :
-
Cost for the turbine
- fc P,v :
-
Flowrate times heat capacity for cold process stream v
- FC P,u :
-
Flowrate times heat capacity for hot process stream u
- F p :
-
Flexibility factor for the increase in pressure in the boiler
- GHG:
-
Greenhouse gas emissions
- ghge f :
-
Unit greenhouse gas emissions for fuel f
- h :
-
Enthalpy
- h 1 :
-
Enthalpy for the steam at the turbine inlet
- ha2 :
-
Actual enthalpy for the steam at the outlet from the turbine
- h f :
-
Saturated fluid enthalpy
- his2 :
-
Outlet isentropic enthalpy
- H Y :
-
Hours per year that operates the plant
- JOB:
-
Total generated jobs
- jobs f :
-
Unit jobs for fuel f
- k F :
-
Factor used to annualize the capital costs
- m :
-
Steam flowrate
- M max :
-
Maximum flowrate in the turbine
- N C :
-
Total number of cold process streams
- N H :
-
Total number of hot process streams
- N p :
-
Factor for accounting for the operating pressure
- N T :
-
Factor accounting for the superheat temperature
- P :
-
Pressure
- P e :
-
Electric power price
- P t :
-
Turbine shaft power output
- Pg1 :
-
Gauge pressure of the boiler
- Q b :
-
Heat load required in the boiler
- Q f :
-
Heat load for the combustion of fuel f supplied to the boiler
- Q process :
-
Heating requirement for the process streams
- s :
-
Entropy
- T :
-
Temperature
- T 1 :
-
Inlet temperature to the turbine
- TAC:
-
Total annual cost
- Tsat:
-
Saturation temperature
- Tsat1 :
-
Saturation temperate for the steam inlet to the turbine
- Tsat2 :
-
Saturation temperate for the steam at high pressure
- T sh :
-
Superheat temperature
- \( t_{v}^{\text{s}} \) :
-
Temperature supplied for cold process stream v
- \( T_{u}^{\text{s}} \) :
-
Temperature supplied for hot process stream u
- \( t_{v}^{\text{t}} \) :
-
Target temperature for cold process stream v
- \( T_{u}^{\text{t}} \) :
-
Target temperature for hot process stream u
- u :
-
Hot process streams
- v :
-
Cold process streams
- W :
-
Work
- Δh is :
-
Isentropic enthalpy difference in the turbine
- η f :
-
Efficiency in the boiler for the fuel f
- η g :
-
Generator efficiency
- η is :
-
Isentropic efficiency for the turbine
- η is :
-
Maximum efficiency in the turbine
- η turbine :
-
Turbine efficiency
- 1:
-
Low pressure
- 2:
-
High pressure
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Bamufleh, H.S., Ponce-Ortega, J.M. & El-Halwagi, M.M. Multi-objective optimization of process cogeneration systems with economic, environmental, and social tradeoffs. Clean Techn Environ Policy 15, 185–197 (2013). https://doi.org/10.1007/s10098-012-0497-y
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DOI: https://doi.org/10.1007/s10098-012-0497-y