Fuel Energy Saving Ratio Research Articles

Energy and Exergy Analysis Of a 44-MW Bagasse-based Cogeneration Plant in India

ABSTRACT In this article, energy and exergy analysis of an ongoing, 44-MW, heat-matched, bagasse-based cogeneration plant of Ugar Sugar Works Ltd (USWL), located in Belgaum, India is presented. In the analysis, exergy methods with more conventional energy analysis are employed to assess the thermodynamic efficiencies and losses. The performance of the plant was estimated, and a detailed break up of energy and exergy losses for the considered plant has been presented. The fuel energy savings ratio of the cogeneration plant is estimated in comparison with separate generation plants. The plant performs with energy and exergetic efficiency of 65% and 25%, respectively. Energy losses mainly occurred in the boiler exhaust and condenser, where 35 MW and 27 MW is lost to environment, respectively. The percentage ratio of the exergy destruction to total exergy destruction was found to be maximum in the boiler system (71%) of fuel exergy input or 45% of the physical exergy input. The total exergy destruction in the...

Cogeneration in Sugar Industries: Technology Options and Performance Parameters—A Review

ABSTRACT This article presents a review of different technological options that are presently being practiced by sugar mills, and technological options that are identified as potentially promising future technologies. Different indices used to gauge the thermodynamic performance of cogeneration plants and facilitate the comparison of alternative systems are discussed. The most important performance parameters used to assess the steam turbine cogeneration plants in general and sugar mill cogeneration plants in particular are defined and developed. Criteria such as energy utilization factor, heat-to-power ratio, fuel energy savings ratio, exergetic efficiency and power generated per tonne of cane (tc) prove to be more important and relevant. Biomass-integrated gasifier/gas turbine cogeneration (BIG-GT) and biomass gasifier combined with steam injected gas turbine cogeneration (BIG-STIG) are considered as potentially promising future technologies. The existing modern, high pressure, high efficiency, steam turbine cogeneration plants generate 115–120 kWh/tc, while BIG-GT and BIG-STIG are potentially capable of generating up to 270–275 kWh/tc. Cogeneration plants using backpressure and condensing steam turbines perform with energy (First Law) and exergetic (Second Law) efficiency of approximately 60–70 % and 22–25%, respectively. The steam consumption in sugar mills at present varies from 480–550 kg/tc, while electricity consumption ranges between 16–22 kWh/tc (32–40 kWh/tc for electrified mills). These performance indices will help plant designers and engineers in improving their choice of system configuration and developing alternative schemes.

Energy utilization evaluation of CCHP systems

Combined cooling, heating and power (CCHP) is getting more attention for its energy saving. However, until now it is not clear yet that how to evaluate the energy utilization of CCHP scientifically and if energy saving is intrinsic to CCHP systems. One of the reasons for this lies in the inappropriate selection of reference situations that making the comparison between the gas cogeneration and the separate production fueled by coal. Another is that the ideal efficiencies of CCHP units are often cited and the differences of various practical performances are often ignored in the comparison. In this paper, an appropriate reference situation is suggested and the practical statistical performances of various units are introduced. Then, a static calculation methodology for evaluating the primary energy consumption for CCHP and separate productions is presented. Fuel energy saving ratio (FESR) definition and the boundary conditions that have to be met by CCHP systems for being energy saving to separate productions are given. Moreover, the energy saving performances of various types and sizes systems in heating and cooling modes are analyzed. Energy saving is not intrinsic but conditional to CCHP systems. The systems with the larger electric power have the higher energy saving potential.

Energy analysis of a cogeneration plant using coal gasification and solid oxide fuel cell

This paper presents a conceptualized combined heat and power (CHP) scheme based on coal gasification and with a high temperature, pressurized solid oxide fuel cell (SOFC) in the topping cycle and a bottoming steam cogeneration cycle. An energy analysis is done for this CHP plant. The study reveals that such a plant offers a substantial saving in fuel with respect to separate plants for the same power and utility heat. The total power of the plant optimizes at a pressure ratio for a given cell operating temperature. However, this optimum pressure ratio increases with higher cell operating temperatures. On the other hand, the utility heat rate decreases with the increasing pressure ratio for any cell operating temperature. In a combined effect of these utility outputs (i.e. power and utility heat), the overall performance of the plant, expressed by fuel energy savings ratio (FESR), is found to optimize at a particular pressure ratio for a given cell operating temperature. For example, the maximum FESR is found to be 30% for an optimum pressure ratio of about 18 for a cell operating temperature of 1273 K.

Thermodynamic performance simulation of a coal gasification and SOFC based combined cogeneration plant by energy and exergy analyses

This paper presents a thermodynamic model of a combined cogeneration plant that employs a coal gasifier, a gas cooler and a solid oxide fuel cell (SOFC) upstream of the gas turbine and a downstream HRSG to generate process steam at low pressure. Simulated performance of the plant with respect to variations in some design and operating parameters has been reported. While energy analysis indicates that such a plant would offer a large fuel saving, the exergy analysis identifies the components responsible for major exergy destructions. Higher pressure ratio across the GT is found to improve the energetic as well as exergetic performance of the plant. Higher fuel cell operating temperature is found to have adverse effect on the fuel energy savings ratio of the plant. However, this increases the exergetic efficiency of the SOFC although it does not significantly affect the performance of the other plant components.