Zeljko Bogdan

Optimization model for EL-TO Zagreb cogeneration plant

A mathematical model for the cost optimization of the EL-TO Zagreb thermal power plant has been developed. The plant supplies hot water for district heating, process steam for industry and electric power. The rather detailed mathematical model of the plant includes models of all main components like gas turbine facilities with heat recovery boilers, high pressure steam generators, back-pressure turbines, peak load boilers and other equipment like heat exchangers, deaerators and pressure reduction valves. All boilers can use alternatively natural gas or heavy oil as fuel while gas turbines are supplied with natural gas only. The generalized reduced gradient method was used for solving the strongly nonlinear optimization problem. The goal of the mathematical model was to minimize the production cost by satisfying the district heat and industrial steam consumption. Results of the sensitivity analyses of the influence of extraction steam pressure levels on cost function are presented as well as a comparison of optimization results with operational data.

Cost Optimization of a Cogeneration Plant

The software package for optimization of the cost of the thermal power plant operation was developed. The plant supplies hot water for district heating, process steam for industry and electric power. The mathematical model of the plant includes four steam generators, two back-pressure turbines and other equipment like heat exchangers, deaerators and pressure reduction valves. Two optimization approaches were tried. The first one used a general-purpose optimization solver that may be found in commercial packages, without satisfactory results. The second one was the self-developed solver reflecting the design philosophy of the plant. The optimization package was tested against the plant custom operation modes. For this purpose the consumption data for two month, typical for winter and summer mode of plant operation, were chosen. In both cases cost savings ranging from 0.8% to 5.5% have been obtained.

A new approach to CFD research: combining AVL's FIRE code with user combustion model

A new oil-combustion model was implemented into the AVLs CFD code FIRE and validation performed. The validation consisted of the simulation and the comparison with the existing Magnussen model. For the simulation purpose the domain was determined first, while user-defined functions simulating conditions at the inlet were done subsequently. The comparisons with the Magnussen results as with some approximate experimental results were done at the end. The paper shows flexibility of AVLs code in usage of user-defined functions, which enables combining the advantages of a commercial code and user modelling.