دانلود رایگان مقاله مفهوم CHP نوآورانه برای ORC و سود آن نسبت به مفاهیم متعارف

abstract

Combined heat and power is highly favorable in order to prevent harmful CO2-emissions. Besides that, economic benefits go along due to higher full load operation hours. The present work investigates the flexibility and suitability of different Organic Rankine Cycles for combined heat and power concepts, since it can play a significant role to achieve climate goals. An integrated concept for heat decoupling based on a two-stage Organic Rankine Cycle with regenerative preheating from turbine bleeding is introduced. The heat extraction to the district heating system is directly in line with the receiver tank for the preheating. The flexibility of this integrated concept is determined for different isentropic fluids and siloxanes. Under general circumstances it is more favorable to apply a recuperator for dry fluids such as siloxanes, due to the high amount of sensible heat after the turbine outlet. It has been shown in this work, that the proposed regenerative preheating concept is more beneficial for combined heat and power. While other concepts are only applicable for base load heat demand or for peak load heat demand, this concept is suitable for the entire range of cover ratios of a district heating system. Thus, this concept offers highest flexibility in application and a good capacity utilisation.

6. Conclusion

A Two-stage ORC-CHP system has been proposed, where heat extraction to the DHS is integrated into the regenerative preheating. The following conclusions can be drawn from the presented results: 1. For different isentropic working fluids the performance and the flexibility of the Two-stage ORC-CHP system was investigated and shows a flexible CHP coefficient combined with high electric efficiencies. A comparison of isentropic working fluids showed, that Furan and 2,5-Dihydrofuran perform best for temperatures of 240 C and 340 C of the heat transfer fluid. 2. It was shown, that the excess heat transfer area during part load condition has a positive effect on the electricity production, since pinch point limitations are reduced during part load operation. 3. Moreover, advantages for dry fluids were identified as well. Since the proposed concept shows a high and continuous electricity production during heat decoupling to the DHS, the system becomes beneficial for high heat demands. However, for small heat demands, a Parallel ORC-CHP concept with recuperator is still the best option. 4. Large cover ratios of the DHS heat demand, lead to a significant part load operation of the ORC. Therefore, the Two-stage Concept becomes more beneficial for such large cover ratios. 5. Finally, the benefits of such a Two-stage ORC have been supported by annual cumulated electricity revenues. However, these additional revenues depend strongly on the shape of the annual load duration curve as well as heat and electricity prices.