Papers by Keyword: Cogeneration

Abstract: With development of the economic, China has been the largest cement production country in the world. But the big production of cement also causes serious ecological environmental problems. In this study, a cradle-to-gate life cycle assessment was carried out for four typical cement factories in China. The results indicated that new suspension preheater (NSP) process and power plant were mainly to blame for most emissions and environmental performances, and GWP is the most prominent category in the accumulative environmental performance of cement production. Any of the strategies for cleaner production of cement considered in this study, including larger production scale, cogeneration and using calcium carbide slag as secondary material, has effect in improving the environmental performance, but the final single result show that the utilization of calcium carbide slag is the best method, and it could reduce the environmental impact obviously.

Abstract: The integration of power and vapor absorption refrigeration cycle overcomes the disadvantages of power used for the compression refrigeration and also produces additional power for other purposes (Low pressure turbine). The integration is done by making the heat exchanger and generator as common and separate super heater and reheater is used to run the high pressure turbine (HPT) and low pressure turbine (LPT). The maximum total power output of 69.78 kW and 31.86 kW is obtained for HPT and LPT at the atmosphere temperature 30 °C and separator temperature 180 °C. At the same collector exit and atmosphere temperature shows the maximum cooling output of 188.88 kW. The additional advantages of integrating the power and cooling cycle’s shows the choice of choosing the need of only power only cooling and both power and cooling. The analyses are done for various separator temperature and strong solution concentration.

Abstract: Biogas is a fuel made from the anaerobic digestion of organic material to form methane. It can be used to power a stationary engine to generate electricity making it a viable method of decentralised power generation from renewables. However, biogas is a mixture of methane and carbon dioxide, and other trace gases such as hydrogen, hydrogen sulphide and oxygen. As such the quality can vary and setting the air-fuel ratio for efficient combustion can be problematic under these conditions. The Wobbe Index, or Wobbe Number, is a quality of combustible gases that allows the air-fuel requirement to be determined. This work presents a novel type of Wobbe Index sensor based on a miniaturised capillary viscometer that can be used with biogas. The sensor is validated at a biogas cogeneration plant which uses a stationary engine and the results are compared to a methane sensor installed at the plant.

Abstract: The article presents selected problems related to the design and operation of small chp units used in individual biogas plants. There are presented and commented available design solutions that can match operational and cost-effective requests in relation to the engine, generator type selection, to design solutions of ignition system, fuelling system, waste heat utilization system and control unit. Presented solutions are discussed in terms of the unit reliability, power and heat generation efficiency and overall unit price. In conclusion, there are proposed some optimal design solutions for typical applications of small biogas fuelled chp units

Abstract: In the paper presented is a concept to utilize waste heat from the power plant with the aid of the low-temperature ORC cycle. The ORC system is heated from two heat sources, the first one being the flow rate of waste heat obtained from the exhaust gases. Subsequently, the working fluid in the cycle is additionally heated by the condensing steam from the low pressure turbine extraction points increasing in such way the level of temperature of working fluid before turbine to 120°C. Examination of the results enables to conclude that the overall efficiency of the cycle increased from =51.958% to =52.304%. That is due to the fact that additional heat enabled to evaporate more working fluid. The total generated power increased to the value of N_elRU=915.85MWe, which corresponds to about 1.5% increase in power.

Abstract: Resources of wind power due to its presence greater volatility, increasing the difficulty of regulating for the power grid. In the supply side, by installing thermal storage device to the cogeneration units so as to increase the adjusting capacity in the supply side of the power system, in the load side, the wind power heating system added heat storage device, increasing the load that can be adjusted. These two measures could be better to solve the problem that part of the abandoned wind. In this paper, analyzed the theoretical basis of each system briefly, added thermal storage device in electric –thermal combine system, and the thermal storage device installation position has been described too. Due mostly theoretical on thermal storage device is about the thermodynamic aspects, it is rather strange for electricity workers, so in this electrical-thermal combined system, its thermal storage devices and electric boiler thermal model have been made a simple analysis and described its control strategy. The control strategy was a comprehensive coordination to the power grid, meanwhile, taking into account the hysteresis characteristics, delay effects and daily regulation plan features of the thermodynamic parameters of thermal storage system make a reasonable start-stop control strategy finally.

Abstract: This work presents the thermodynamic, thermoeconomic, and economic analyses of utilization of waste materials from industrial processes of a modern Brazilian sugarcane mill (bagasse, straw and vinasse) for energy production. The first case considers a conventional steam thermal power plant constituted, among other equipment, by a steam boiler of high-pressure and high-temperature and by an extraction-condensation steam turbine, being all mechanical driving electrified, and using just bagasse as fuel. The second case considers a modified steam thermal power plant in which is incorporated systems to be possible the utilization of straw and vinasse as complementary fuel to bagasse by means of a combined cycle, with the addition of a gas turbine and a heat recovery steam generator, among other equipment.

Abstract: Thermoelectric cogeneration may be applied to the exhaust of an automobile to generate additional electric power, by applying a temperature differential across the thermoelectric power generation modules. To obtain maximum net power, the highest allowable temperature difference should be obtained. Therefore, a cooling system should be employed to ensure that the cold side of the thermoelectric modules remain as cold as possible. An evaporative cooling system patented by Einstein and Szilard is used as a base for a non-parasitic cooling system to be used together with thermoelectric modules. The cooling system utilizes the same heat which powers the thermoelectric modules as a power source. By utilizing the high solubility of ammonia in water, the solubility dependency with temperature, and usage of polar and non-polar solvents to direct the flow of ammonia as a coolant, it is possible to create a cooling system which performs better than passive heat sinks, but negates the power requirements of active cooling systems.

Abstract: Cogeneration is regarded as an important approach to probe new profit increase and achieve the long term goal of sustainable development. In the present paper, cases of heating rebuilding for units with different capacities are analyzed. Additionally, four cogeneration bases on the energy cascade utilization are proposed, which makes full use of the extracted steam heat, flue gas waste heat and low pressure cylinder exhaust steam condensation heat. The proposed technical approaches for cogeneration have the merits of excavating energy saving potential in depth and achieving economic benefits to the maximum value. Under the increasingly stringent circumstances of energy conservation and emissions reduction policies, accelerating the implementation of the technical proposals for heating rebuilding of thermal power units has promising applications and benefits.

Abstract: In order to assess the operational efficiency of cogeneration heating system and measure the systems social, economic, energy-saving and environmental protection benefits in North China, an evaluation index system is built up after analyzing the influence factors which may impact the heating system operation. The association degree function of classical matter element method is improved. And then, an improved matter-element evaluation model is established, which not only can figure out the evaluation grade that heating system belongs to, but also can point out the direction of the further improvement work. Besides, the model has other merits, such as uncomplicated operation, good scalability and so on. Example indicates that this evaluation model has excellent applicability and operability.