The Optimization Method Of The Process Systems Based On The Avoidable Exergy Destruction And The Investment Costs

Energy, environment and economic efficiency have raised people's attention, so the optimization of the process systems is becoming more and more important. The optimization methods of thermoeconomics (exergoeconomics) based on the second law of thermodynamics are developing very fast recently because of the advantage of the methods. Total exergy destruction and equipment investment of the units of the process systems are now used in the optimization methods of the exergoeconomics, but some of the exergy destruction and the equipment investment are unavoidable because of the restrict of technology and other conditions. The avoidable exergy destruction and the equipment investment are more important than the total exergy destruction and equipment investment in the optimization. The exergoeconomics optimization method based on the avoidable exergy destruction and the equipment investment is more meaningful than the common exergoeconomics optimization methods. The researches of this paper are as following:1. The exergy destruction and equipment investment of the units of the process systems are studied, and the exergoeconomics optimization method based on the avoidable exergy destruction and the equipment investment is proposed.The modified exergy efficiency f'K, exergoeconomics factor e'K, relativecost difference r*K with the avoidable exergy destruction and the equipmentinvestment are defined.2. The unavoidable exergy destructions and the equipment investments of the units of the process systems are discussed. The conditions for calculating the unavoidable exergy destructions and the equipment investments of the typical units of the process systems are analyzed.3. In order to optimize the process system easily and conveniently, some programs of exergy analysis and economic analysis are developed based on the other optimization programs, such as THESIS.4. As an example, Air separation unit of Refinery-residual-Based IGCC systems is optimized by the new method developed by this paper. The optimization method and the programs are testified.