共查询到20条相似文献,搜索用时 31 毫秒
1.
1-N型热交换链的(火用)传递分析 总被引:4,自引:0,他引:4
依据工程传递原理建立1-N型热交换链的传递模型,并确立相应的评价准则。对动力锅炉内热交换过程的 各输元及全过程进行了传递计算及分析,并与传统的传热分析及分析比较,提供了一些新的技术评价信息。 相似文献
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《Heat Recovery Systems and CHP》1990,10(1):37-48
Cogeneration systems often provide a very effective means of integrating power generation with the provision of thermal energy to an industrial process. Various types of power generating machines can be used, but combined cycle cogeneration systems can offer significant advantages over other technologies in many medium and large scale applications. The systems that are used consist of fired prime movers (usually gas turbines), discharging their exhaust heat into heat recovery steam generators. The steam raised in this way is passed through back-pressure steam turbines to extract additional power before finally delivering its residual heat content to process heating duties.This paper presents an overview of the economic trade-offs in the design of single cycle and combined cycle systems. Generalizations are derived from this investigation, leading to the identification of three distinct classes of problem for which different types of cogeneration systems (combined cycle or single cycle) are appropriate. Case study results are presented to illustrate the principles employed. 相似文献
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G. V. Nozdrenko P. A. Shchinnikov F. A. Serant V. G. Tomilov N. G. Zykova P. Yu. Kovalenko E. E. Russkikh 《Thermophysics and Aeromechanics》2009,16(2):315-323
Fundamental principles of complex exergy analysis of new boiler technologies within power-generating units of thermoelectric
power stations are set out. Results of analysis are stated. 相似文献
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《Heat Recovery Systems and CHP》1995,15(1):41-50
The performance of gas turbines, operated either as a simple cycle or a combined cycle, is critically constrained by the prevailing ambient temperature, particularly in arid and tropical climates. This paper investigates the option of cooling the intake air to the compressor of the gas-turbine system using an absorption chiller in order to increase the gas turbine capacity. High-temperature waste heat from the exhaust gas may be utilized to produce steam in a recovery boiler. Part of the steam produced could then be used to drive a lithium-bromide double-effect absorption chiller which in turn could cool the incoming air. An analysis carried out by taking the weather data of Bangkok (Thailand) indicates that reducing the temperature from ambient condition to 15°C could help to increase the instantaneous power output between 8 and 13%. As an outcome, as much as 11% additional electricity could be generated from the same gas turbine power plant.A simple economic assessment indicates that the proposed scheme will require a minimal investment as compared to the commissioning cost of a new gas turbine unit to meet the corresponding capacity increment. The latter will need nearly four times higher initial cost than the amount estimated for the proposed scheme. Thus, implementation of such a system would significantly abate the negative impact of the ambient temperature, while providing an economically and environmentally attractive option for energy producers in most developing nations of the world which are located in arid and tropical zones. 相似文献
5.
基于LNG冷能的发电技术 总被引:1,自引:1,他引:0
液化天然气将成为人类在21世纪的主要能源之一。该文阐明了蕴涵在液化天然气中的巨大冷能利用价值,并指出两种利用方式:改善现有动力循环和相对独立的低温动力循环。前者主要体现在与燃气轮机及锅炉余热结合上,分析结果表明系统的热效率和火用效率普遍较高;后者则主要包括低温条件下的Rank ine循环、B rayton循环以及改进和复合的循环。总结了各种利用途径的特点和效果,同样说明了相当可观的液化天然气冷能利用价值。根据研究现状,最后指出了有待进一步研究和解决的诸多问题。 相似文献
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Thermal power plant is one of the important thermodynamic devices, which is very common in all kinds of power generation systems. In this paper, we use a new concept, entransy loss, as well as exergy destruction, to analyze the single reheating Rankine cycle unit and the single stage steam extraction regenerative Rankine cycle unit in power plants. This is the first time that the concept of entransy loss is applied to the analysis of the power plant Rankine cycles with reheating and steam extraction regeneration. In order to obtain the maximum output power, the operating conditions under variant vapor mass flow rates are optimized numerically, as well as the combustion temperatures and the off-design flow rates of the flue gas. The relationship between the output power and the exergy destruction rate and that between the output power and the entransy loss rate are discussed. It is found that both the minimum exergy destruction rate and the maximum entransy loss rate lead to the maximum output power when the combustion temperature and heat capacity flow rate of the flue gas are prescribed. Unlike the minimum exergy destruction rate, the maximum entransy loss rate is related to the maximum output power when the highest temperature and heat capacity flow rate of the flue gas are not prescribed. 相似文献
8.
《Heat Recovery Systems and CHP》1988,8(6):529-536
The technical advantages and disadvantages resulting from locating a steam turbine unit close to a geothermal well-head are presented. The short steam piping system has implications in the design of a well-head turbine. It is concluded that there are some technical differences between large geothermal turbines and well-head units, which may be decisive in the selection of geothermal plant. 相似文献
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The method of exergy analysis is presented for a SOFC power plant involving external steam reforming and fueled by ethanol
and methane. The optimal operation parameters of the integrated SOFC plant are specified after minimizing the existing energy
and exergy losses. A comparison of methane and ethanol as appropriate fuels for a SOFC-based power plant is provided in terms
of exergetic efficiency assuming the minimum allowable (for carbon-free operation) reforming factors for both cases. Then,
a parametric analysis provides guidelines for practical design. It is concluded that the exergy calculations pinpoint the
losses accurately and that the exergy analysis gives a better insight of the system's process.
Paper presented at the 9th EuroConference on Ionics, Ixia, Rhodes, Greece, Sept. 15 – 21, 2002. 相似文献
11.
利用LNG冷能的混合工质中低温热力循环开拓研究 总被引:11,自引:1,他引:10
为提高中低温余热回收动力系统性能,本文在常规混合工质热力循环(火用)分析基础上,提出了结合LNG冷能利用的新型混合工质热力循环。通过与LNG的有机结合,混合工质热力循环热效率提高14.5个百分点,(火用)效率达到53.6%。为进一步揭示效率提高的原因,我们比较了常规混合工质热力循环与LNG-混合工质热力循环的(火用)损失变化情况。结果表明:LNG-混合工质热力循环高效的关键在于循环平均放热温度的降低以及工质蒸发过程与冷凝过程换热的合理匹配。而LNG冷能的梯级利用则是系统具有较高(火用)效率的根本原因。 相似文献
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《Heat Recovery Systems and CHP》1987,7(6):465-472
Use of pressurized, fluidized-bed combustion (PFBC) has given a new opportunity to use municipal refuse as fuel for combined gas and steam power cycles keeping the pollutants of sulphur and nitrogen oxides to a minimum at reduced capital cost.In combined gas and steam power cycles, the heat energy in the exhaust gases of a simple gas turbine cycle is used to generate steam in a waste-heat boiler and the generated steam is used in the steam turbine for power generation.The effects of gas turbine pressure ratio and inlet temperature on the main parameters of refuse-fired, pressurized, fluidized-bed combustion combined cycles are determined.The results indicate a maximum combined cycle thermal efficiency and work output at a possible range of optimum pressure ratios between 10 and 12 for a range of gas turbine inlet temperatures of 750–1000°C. 相似文献
14.
《Heat Recovery Systems and CHP》1994,14(2):211-220
The Pinch Technology and the MIND method are combined in the analysis of a Swedish refinery. The heat exchanger network of the crude distillation system is analysed using the Pinch Technology. The results show that the steam demand from the boiler units in the energy supply part of the system can be reduced by 20% in the optimized heat exchanger network and by 21% when a heat pump is added to the system. A multi-period cost optimization of the operating strategy is performed using the MIND method. The results from the Pinch analysis are then input to the MIND optimization. The system cost of the total energy system of the refinery is optimized with regard to flexibility in the process system as well as changes of energy costs and the operating conditions of the cogeneration unit. The combination of methods shows that significant capital savings can be achieved when the energy saving potential of the process system is integrated in the overall operating strategy of the energy system. It is, in this case, possible to compare investments in energy saving measures to investments in increased steam production capacity. 相似文献
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A finned convergent-divergent plate-type cross-flow heat recovery unit is manufactured and tested for efficiency analysis. Temperature and pressure drop experiments are conducted with various working conditions of the boiler, fan, preheater, and reheater of the system. Variation of Nusselt number and friction factor with Reynolds number is analyzed. Variation of effectiveness and exergy loss with number of transfer units is calculated and discussed in terms of extant literature. Experimental results indicate that the most important parameter affecting the heat transfer is winglet geometry and fluid velocity. The efficiency can be improved successfully by controlling these parameters for thermal applications. 相似文献
17.
The approach was developed for creation of high-speed mathematical models of cogeneration turbines; these models are the tools
for fast optimization of operation modes of large-scale cogeneration heating plants. The approach was developed for identification
of mathematical models of steam turbines via measuring its parameters. The example of parameters identification is presented
for steam turbine T-100/120–130. The optimization computations of operation modes for a cogeneration heating plant were the
basic ones for plotting equivalent energy characteristics at a given consumer heat load. 相似文献
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B. N. Okunev N. M. Voskresensky I. S. Girnik Yu. I. Aristov 《Journal of Engineering Thermophysics》2018,27(3):327-338
Thermodynamic analysis of a new adsorption cycle recently suggested for upgrading ambient heat (the so-called “Heat from Cold” or HeCol cycle) was performed. The energy and entropy balances at each cycle stage and in each converter component were calculated for the methanol–AC-35.4 activated carbon working pair under conditions of ideal heat transfer. It is shown that useful heat can be obtained only if the ambient temperature is below a threshold temperature. The threshold temperature was calculated based on the Polanyi principle of temperature invariance and was experimentally validated. The specific useful heat can reach 200–300 J/(g adsorbent), which is of practical interest. The use of adsorbents with an abrupt change in the adsorption uptake between boundary isosters of the cycle may lead to further enhancement of the useful heat. For the HeCol cycle, the exergy losses under the conditions of ideal heat transfer are small. At low ambient temperature, the losses in the evaporator, condenser, and adsorber are comparable, whereas at higher ambient temperature the main exergy losses originate from the adsorber heating and cooling. 相似文献