小型热电联产蒸汽供热系统的能耗分析

目前,有些小型热电联产系统运行不合理、冷源损失大、节能效果不理想.通过对某小型热电联产系统全年运行状况的凋查,计算了热电机组的发电效率、热效率及汽机冷源能量损失,分析了小型热电联产系统能耗大的主要原因,提出了提高热电联产系统能源利用效率、改进热电联产集中供热形式等措施,为热电联产系统改造和扩建工作提供参考.     

yong分析在小型热电站热电联产中的应用

本文采用yong平衡分析法,对小型热电站的热电联产系统进行了yong流分析,得出热电联产系统相比于分散锅炉房的供热系统来讲是具有一定的节能效果的,同时还对热电联产系统内各环节中的yong流损失进行计算,得出各热力设备的yong效率,找出系统用能不合理的主要薄弱环节,为今后设备的工艺过程改进指出了方向。     

小型热电站热电联产分析及节能评价

采用平衡分析法,分别对小型热电联产系统和分散锅炉房供热系统进行了流分析,把两者计算所得效率作一对比,从而得出热电联产系统是取代分散锅炉房供热的节能措施之一。同时还对热电联产系统内各环节中的流损失进行计算,得出各热力设备的效率,找出系统用能不合理的主要薄弱环节,为今后设备的工艺过程改进指出了方向。     

小型热电站热电联产Yong分析及节能评价

采用Yong平衡分析法,分别对小型热电联产系统和分散锅炉房供热系统进行了Yong流分析,把两者计算所得Yong效率作一对比,从而得出热电联产系统是取代分散锅炉房供热的节能措施之一,同时还对热电联产系统内各环节中的Yong流损失进行计算,得出各热力设备的Yong效率,找出系统用能不合理的主要薄弱环节,为今后设备的工艺过程改进指出了方向。     

汽轮机低压缸旁路供热的电出力调节能力分析

为了分析低压缸旁路供热对热电联产机组电出力调节能力的影响,建立了热电联产机组热力系统计算模型和电出力调节能力数学模型,并将计算结果与几种典型热电解耦方案进行比较。结果表明,热电联产机组进行低压缸旁路供热改造后,最大供热能力提升了69.88%,额定供热工况下机组的电出力调节能力提升了42.42%。同一供热负荷下,低压缸旁路供热方案的电出力调节能力高于蓄热罐和电锅炉方案,低于高低压旁路供热方案,但是低压缸旁路供热方案投资成本低、系统简单,不仅可以实现能量梯级利用甚至可以不产生冷源损失,具有更高的实际应用价值。     

发展小型分散热电联产的研究与探讨

介绍了小型分散热电联产的特点、主要型式，分析了小型分散热电联产的成因，还介绍了国内外发展简况，并提出了我国发展小型分散热电联产的几点建议。     

发展小型热电联产的障碍及提高效益的途径

小型热电联产具有节能的优越性,但目前发展较慢。本文根据实际调查,分析了发展小型热电联产存在的一些主要问题,提出了为局长小型热电联产的一些建设性意见     

热电联产、冷热电联产和小型冷热电联产

2000年8月22日国家计委、国家经贸委、建设部、国家环保总局联合发出《关于发展热电联产的规定》,与1998年颁发的《关于发展热电联产的若干规定》相比,发展冷热电联产和小型热电联产的方向更明确了,实际上这两个规定是热电联产、冷热电联产和小型热电联产的规定,为我国建立节能、减少环境污染,提高人民生活水平创造了良好条件,我国发展冷热电联产的新时代已经到来。     

建筑物小型热电联产在欧洲的发展

本文首先介绍了建筑物小型热电联产的特点及其在一些欧洲国家的发展与应用情况。然后指出了小型热电联产对环境污染的改善推广过程中应采取的措施，最后分析了小型热电联产的技术发展特点。     

小型热电联产系统的热效率分析

以装机容量为12MW的某背压式供热机组为例,分冬季和夏季两种工况对小型蒸汽热电联产系统各部分的热效率以及各设备的性能参数进行了分析,得出了热负荷变化对热电联产热效率的影响关系,提出在全年热负荷变化较大的情况下,小型热电机组热效率不高,系统全年节能效果不理想。     

Performance evaluation of an improved biomass-fired cogeneration system simultaneously using extraction steam,cooling water,and feedwater for heating

An advanced cogeneration system based on biomass direct combustion was developed and its feasibility was demonstrated. In place of the traditional single heat source (extraction steam), the extraction steam from the turbine, the cooling water from the plant condenser, and the low-pressure feedwater from the feedwater preheating system were collectively used for producing district heat in the new scheme. Hence, a remarkable energy-saving effect could be achieved, improving the overall efficiency of the cogeneration system. The thermodynamic and economic performance of the novel system was examined when taking a 35 MW biomass-fired cogeneration unit for case study. Once the biomass feed rate and net thermal production remain constant, an increment of 1.36 MW can be expected in the net electric production, because of the recommended upgrading. Consequently, the total system efficiency and effective electrical efficiency augmented by 1.23 and 1.50 percentage points. The inherent mechanism of performance enhancement was investigated from the energy and exergy aspects. The economic study indicates that the dynamic payback period of the retrofitting project is merely 1.20 years, with a net present value of 5796.0 k$. In conclusion, the proposed concept is validated to be advantageous and profitable.     

A district heating system based on absorption heat exchange with CHP systems

In order to decrease the energy consumption of large-scale district heating systems with cogeneration, a district heating system is presented in this paper based on absorption heat exchange in the cogeneration system named Co-ah cycle, which means that the cogeneration system is based on absorption heat exchange. In substations of the heating system, the temperature of return water of primary heat network is reduced to about 25°C through the absorption heat-exchange units. In the thermal station of the cogeneration plant, return water is heated orderly by the exhaust steam in the condenser, the absorption heat pumps, and the peak load heater. Compared with traditional heating systems, this system runs with a greater circuit temperature drop so that the delivery capacity of the heat network increases dramatically. Moreover, by recovering the exhausted heat from the condensers, the capacity of the district heating system and the energy efficiency of the combined heat and power system (CHP system) are highly developed. Therefore, high energy and economic efficiency can be obtained.     

Exergy analyses and parametric optimizations for different cogeneration power plants in cement industry

The cement production is an energy intensive industry with energy typically accounting for 50–60% of the production costs. In order to recover waste heat from the preheater exhaust and clinker cooler exhaust gases in cement plant, single flash steam cycle, dual-pressure steam cycle, organic Rankine cycle (ORC) and the Kalina cycle are used for cogeneration in cement plant. The exergy analysis for each cogeneration system is examined, and a parameter optimization for each cogeneration system is achieved by means of genetic algorithm (GA) to reach the maximum exergy efficiency. The optimum performances for different cogeneration systems are compared under the same condition. The results show that the exergy losses in turbine, condenser, and heat recovery vapor generator are relatively large, and reducing the exergy losses of these components could improve the performance of the cogeneration system. Compared with other systems, the Kalina cycle could achieve the best performance in cement plant.     

改变补水方式的节能效益解析

主要论述以深度除盐水作为补充水的中小型火电厂,尤其是热电厂改变补水方式所带来的双重经济效益;补充水进入凝汽器可利用排汽余热,适当减少冷源损失;将补充水入口从除氧器改为凝汽器,可提高回热经济性。     

A district heating system based on absorption heat exchange with CHP systems

In order to decrease the energy consumption of large-scale district heating systems with cogeneration, a district heating system is presented in this paper based on absorption heat exchange in the cogeneration system named Co-ah cycle, which means that the cogeneration system is based on absorption heat exchange. In substations of the heating system, the temperature of return water of primary heat network is reduced to about 25°C through the absorption heat-exchange units. In the thermal station of the cogeneration plant, return water is heated orderly by the exhaust steam in the condenser, the absorption heat pumps, and the peak load heater. Compared with traditional heating systems, this system runs with a greater circuit temperature drop so that the delivery capacity of the heat network increases dramatically. Moreover, by recovering the exhausted heat from the condensers, the capacity of the district heating system and the energy efficiency of the combined heat and power system (CHP system) are highly developed. Therefore, high energy and economic efficiency can be obtained.     

Regenerative steam-injection gas-turbine systems

There is a demand for developments of the distributed energy system using a small-scale gas turbine. The steam injection configuration can improve the thermal efficiency of simple and regenerative gas-turbine cycles. In this paper, the performance characteristics of two types of regenerative steam-injection gas-turbine (RSTIG) systems are analyzed and they are compared with the performances of the simple, regenerative, water injection and steam injected gas-turbine (STIG) cycles. The thermal efficiencies of the RSTIG systems are higher than those of the regenerative, water injection and STIG systems and the specific power is larger than that of the regenerative cycle. The optimum pressure-ratio for maximum efficiency of the RSTIG systems is relatively low. Furthermore, the steam-injection configuration can be applied in the flexible heat-and-power cogeneration system and the total efficiency of the RSTIG cogeneration system reaches more than 70% (HHV).     

Typical off-design analytical performances of internal combustion engine cogeneration

Based on experimental data, typical off-design characteristic curves with corresponding formulas of internal combustion engine (ICE) are summarized and investigated. In combination with analytical solution of single-pressure heat recovery steam generator (HRSG) and influence of ambient pressure on combined heat and power (CHP) system, off-design operation regularities of ICE cogeneration are analyzed. The approach temperature difference ΔT _a, relative steam production and superheated steam temperature decrease with the decrease in engine load. The total energy efficiency, equivalent exergy efficiency and economic exergy efficiency first increase and then decrease. Therefore, there exists an optimum value, corresponding to ICE best efficiency operating condition. It is worth emphasizing that ΔT _a is likely to be negative in low load condition with high design steam parameter and low ICE design exhaust gas temperature. Compared with single shaft gas turbine cogeneration, ΔT _a in ICE cogeneration is more likely to be negative. The main reason for this is that the gas turbine has an increased exhaust gas flow with the decrease in load; while ICE is on the contrary. Moreover, ICE power output and efficiency decrease with the decrease in ambient pressure. Hence, approach temperature difference, relative steam production and superheated steam temperature decrease rapidly while the cogeneration efficiencies decrease slightly. It is necessary to consider the influence of ambient conditions, especially the optimization of ICE performances at different places, on cogeneration performances.     

空气源热泵空调系统节能分析

节能的分析及优化已不仅仅是能的量的问题，而是能的质与量的综合评价的问题。采用yong分析方法得出空气源热泵空调系统的能耗分布，明确系统yong损失较大的环节。从yong分析得知：压缩机的yong损失占机组能耗的20．5％，冷凝器的yong损失接近总能耗的30％。由此提出了空气源热泵空调系统的节能措施，即应该选用高效率的压缩机，采用强化传热措施，提高传热系数，减小传热温差，同时还应注意改善热泵机组的周围环境，使系统yong损失最小，yong效率最大，实现空气源热泵空调系统的节能优化.     

Numerical simulation of underground seasonal cold energy storage for a 10 MW solar thermal power plant in north-western China using TRNSYS

This paper aims to explore an efficient, cost-effective, and water-saving seasonal cold energy storage technique based on borehole heat exchangers to cool the condenser water in a 10 MW solar thermal power plant. The proposed seasonal cooling mechanism is designed for the areas under typical weather conditions to utilize the low ambient temperature during the winter season and to store cold energy. The main objective of this paper is to utilize the storage unit in the peak summer months to cool the condenser water and to replace the dry cooling system. Using the simulation platform transient system simulation program (TRNSYS), the borehole thermal energy storage (BTES) system model has been developed and the dynamic capacity of the system in the charging and discharging mode of cold energy for one-year operation is studied. The typical meteorological year (TMY) data of Dunhuang, Gansu province, in north-western China, is utilized to determine the lowest ambient temperature and operation time of the system to store cold energy. The proposed seasonal cooling system is capable of enhancing the efficiency of a solar thermal power plant up to 1.54% and 2.74% in comparison with the water-cooled condenser system and air-cooled condenser system respectively. The techno-economic assessment of the proposed technique also supports its integration with the condenser unit in the solar thermal power plant. This technique has also a great potential to save the water in desert areas.     

基于等价煤耗法的热电联产机组热经济性分析

热电联产机组热经济性代表了热电厂能量利用水平、热功转换技术的先进水平和运行的经济水平,因而准确地分析热电联产机组热经济性显得尤为重要.等价煤耗法是把电厂实际发电效益和供热效益通过热、电等价转换,得到等价发电量,进而得到等价煤耗率.结合300 MW机组,首先分别用热量法、实际焓降法和等价煤耗法对热电联产机组煤耗率进行计算,并通过分析比较,证明了等价煤耗法在评价热电联产机组方面的可行性和准确性;其次比较了同一热电联产机组在供热期和非供热期的煤耗率——供热期煤耗率比非供热期煤耗率低,从而证明了热电联产机组在节能方面优于纯凝机组.