Mateusz Brzęczek

Thermodynamic and economical analysis of the ORC module application to an existing combined heat and power unit with the backpressure turbine

This paper presents the results of the thermodynamic and economic analyses of two variants of integration of a CHP unit with ORC modules. The first variant consists in an integration of a CHP unit with a single ORC module. The module is installed on one of the steam outlets from the asymmetric part of a back-pressure steam turbine. The second variant assumes installation of modules on two outlets of this part of the steam turbine. An argument for the integration of a unit with ORC modules is the ability to obtain in the summer period additional electric power based on the use of heat, which in the period of lower demand for heat is dissipated in the environment. For these two variants, the thermodynamic analysis was carried out, which allowed to determine the electrical power that can be generated by ORC modules. Analyses were performed for various low-temperature boiling fluids. Economic analyses were also performed, which allowed to determine the net present value and the internal rate of return for the two variants of integration. Assumptions required to perform economic analyzes were adopted. As a part of the economic analysis, sensitivity analysis of the selected economic effectiveness indicators on the relative change of the investment cost and electricity prices was performed. The influence of changes of working time of the integrated unit within a year and the discount rate was also examined. The obtained results indicate a high potential of the proposed integrations. Supplying of ORC modules by steam leaving the backpressure steam turbine can allow for economically justified extension of the period of operation of many CHP units. Appropriate modernizations in the case of switched off post-industrial CHP units can contribute to the restoration of their ability to generate profit.

The influence of carbon capture and compression unit on the characteristics of ultramodern combined cycle power plant

In this paper, the influence of carbon capture and compression unit on the characteristics of ultramodern combined cycle power plant is presented. The chemical absorption of the CO2 from the flue gases using MEA in the carbon capture unit was used. The effective use of heat recovered from the turbine blade cooling air in order to increase the efficiency of combined cycle power plant with the carbon capture and compression unit is proposed. The power plant is analysed in a wide range of compression ratios and temperatures in the gas turbine. Thermodynamic and ecological characteristics of this combined cycle unit as a function of the basic operating parameters are made. The equation connecting the efficiency of combined cycle power plant with and without the carbon capture and compression unit is proposed. The calculations indicate that the reduction of energy consumption of the absorbent by 1 MJ/kgCO2 causes an increase in net electric efficiency of the unit by 1.25 percentage points. The analysed combined cycle power plants are characterised by the highest electricity generation efficiency achievable for large energy units and exceptionally low CO2 emissions, lower than 41 kg/MWh throughout the analysed range of compression ratio.

The improvement of environmental characteristics of the combined cycle power plant by the implementation of the carbon capture installation

The paper describes a combined cycle power plant with carbon capture installation in a post-combustion technology. Carbon dioxide is separated from flue gas by using a chemical absorption method with monoethanolamine (MEA) as a sorbent. Separated carbon dioxide is compressed in order to prepare for transportation to the storage place. This paper identifies the electric efficiencies and other characteristic parameters of power plants before and after implementation of CO2 capture installation, as well as the power plant efficiency drop, and the improvement of ecological characteristics related to the implementation of this installation. The implementation of the installation described herein is associated with the efficiency loss caused by the auxiliary power for additional installations. The CO2 separation installation is powered by heat energy required for reclaiming the sorbent. This energy is taken in the form of steam extracted from the steam cycle, thus reducing the steam turbine power output, while the CO2 compression installation is powered by electric energy.