Wyniki wyszukiwania - Biblioteka Nauki

1

Analiza termodynamiczna ultra-nadkrytycznego bloku węglowego z turbiną pomocniczą

100%

Stępczyńska-Drygas K. , Dykas S.

Zeszyty Naukowe Politechniki Rzeszowskiej. Mechanika

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2014

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tom z. 86 [290], nr 1

79--86

PL

Konieczność zmniejszenia emisji gazów cieplarnianych oraz poprawy ekonomiki wytwarzania energii elektrycznej spowodowały znaczny postęp w dziedzinie bloków węglowych. Nowe perspektywy otwiera generacja bloków na zaawansowane parametry ultra-nadkrytyczne pary o temperaturze 700°C/720°C. Znaczne zwiększenie temperatury pary, zwłaszcza wtórnie przegranej, pogłębia problem różnicy temperatur w podgrzewaczach regeneracyjnych zarówno wysoko jak i niskoprężnych, co skutkuje wzrostem strumieni generowanej entropii oraz problemami materiałowymi. Rozwiązaniem może być wprowadzenie do obiegu dodatkowej upustowo-przeciwprężnej turbiny pomocniczej. Obieg turbiny pomocniczej jest prostym obiegiem bez przegrzewu wtórnego. Skutkuje to tym, że ma on niższą sprawność w porównaniu do obiegu głównego. Zmniejsza się zysk z zastosowania przegrzewu międzystopniowego, gdyż znaczny strumień pary, który jest kierowany do turbiny pomocniczej nie zostaje przegrzany ponownie. Zysk wynikający z minimalizacji generacji entropii w podgrzewaczach regeneracyjnych powinien zatem zrekompensować straty wynikające ze znacznego zmniejszenia strumienia przegrzewanej pary. W artykule przedstawiono analizę termodynamiczną obiegu prostego oraz koncepcyjnego bloku węglowego na zaawansowane ultra-nadkrytyczne parametry pary o mocy 900 MW z upustowo-przeciwprężną turbiną pomocniczą.

EN

The necessity of the reduction of greenhouse gases emissions and improving the economics of electricity generation resulted in significant progress in the development of the coal-fired power plants. New perspectives gives the generation of power plants for advanced ultra-supercritical (A-USC) steam parameters of temperature of 700°C/720°C. A significant increase of the steam temperature, especially reheated, increases the problem of the temperature differences in the high and low-pressure feed water heaters. This results in the increase of generated entropy and material problems. The solution can be introducing into the steam cycle an auxiliary extraction-backpressure turbine (AT). The AT cycle is a simple cycle without steam reheating. As the result it has lower efficiency in comparison with the main cycle. The use of the AT leads to the reduction of profit resulting from the reheating of steam, because the mass flow of steam transmitted to the boiler reheater is reduced. The benefit resulting from the decrease of the entropy generation in the feed water heaters should then exceed the loss related with the reduction of the steam mass flow, which is reheated in the boiler. In the paper the thermodynamic analysis of the simple cycle and the conceptual 900 MW power plant with the auxiliary extraction-backpressure turbine is presented.

2

Economic evaluation of A-USC power plant with CO2 capture unit

80%

Stępczyńska-Drygas K. , Dykas S. , Łukowicz H. , Czaja D.

Journal of Power Technologies

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2015

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tom Vol. 95, spec.

75--83

EN

Achieving CO2 emission control while keeping electricity prices competitive is one of the most important economic and technical challenges. The strategy for lowering the CO2 emission from the coal-based power plants includes first of all raising electricity generation efficiency. Currently, steam temperatures in ultra-supercritical (USC) power plants are limited to approximately 627ºC by the use of the most advanced commercially available ferritic steels. To go to higher temperatures, high-nickel alloys must be used. The nickel alloys are at an advanced stage of development and are expected to be available to support construction of a demonstration plant in Europe in 2021. For pulverized coal (PC) plants the development means progressing to advanced ultra-supercritical (A-USC) steam conditions - 35MPa/700/720ºC. It turned out that the concept consists in gradually raising the live steam temperature and pressure can become economically unjustified. Cost-effectiveness of new investments can be provided only by a significant increase in the efficiency of electricity generation. In the paper the economic evaluation of 900 MW PC unit is presented. The main aim is to compare the cost of electricity generation in USC (28MPa/600/620ºC) and A-USC (35MPa/700/720ºC) power unit. The variants with CO2 capture installation by chemical absorption MEA are considered. Compared to a USC design, the capital cost of the A-USC PC plant will be higher, but the operating cost will be lower. Because of the higher efficiency of the A-USC plant, the differential in operating cost increases as fuel price increases and CO2 cost charges are included.

3

Operation of conceptual A-USC power unit integrated with CO2 capture installation at part load

70%

Stępczyńska-Drygas K. , Bochon K. , Dykas S. , Łukowicz H. , Wróblewski W.

Journal of Power Technologies

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2013

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tom Vol. 93, nr 5

383--393

EN

Nowadays, the main aim of the development of coal-fired power industry concentrates on improving the efficiency of electricity generation and on reducing the CO2 emission. Modern power systems require from the power units ability to flexible work at part loads with high efficiency. The paper presents the conceptual 900 MWcoal-fired power unit. Unit operates with advanced ultra-supercritical (A-USC) steam parameters 35MPa/700ºC and net efficiency of 49%. Improvement of the efficiency results in significant reduction of CO2 emission. Further reduction of emission requires integration of coal-fired power plants with CO2 capture installation. Newly built power plant offers a possibility of fully optimized integration to reduce the efficiency loss, which is related with post-combustion capture process. The CO2 capture by wet chemical absorption MEA can be characterized with three indicators: the demand for heat, electric power to drive auxiliary equipment and cooling. In order to calculate these indicators the capture process was modeled in Aspen Plus. Calculated indicators for nominal and part load operation were used to model integrated power unit in Ebsilon Professional 10.0. The characteristics of operation of power unit integrated with CO2 capture installation were determined.