垃圾焚烧发电项目余热锅炉中参数和高参数的对比分析

垃圾焚烧发电厂蒸汽参数的选取直接影响垃圾焚烧发电厂的发电效率和收益,提高蒸汽参数成为提高发电效率的重要途径。根据对国内主流垃圾焚烧发电项目投建方和设备厂家的调研及理论分析,对中参数和高参数项目在技术特点、设备投资、维护成本、经济收益等方面进行了比较研究。采用高参数余热锅炉的项目,其设备成本和运营维护成本均较高,但发电量收入增加显著;项目的处理规模越大,采用高参数的经济收益越明显,设备投资静态回收期越短,经济优势越明显。     

次高压汽轮机技术经济性探讨

本文叙述了热电联产依次高压机组的经济性优于中压机组.抽汽凝汽式供热机组的技术与经济比较.次高压热电厂的合理配置等.通过理论探讨和实例分折,提出了中小型热电厂汽轮机的造型和合理匹配的建议.     

发掘现有工业锅炉潜力实现热电联供

热电联供、集中供热是世界动力工业的发展趋势。在我国能源的开发与节约并重的政策中,热电联供有特殊优势,日益受到重视。为贯彻能源部规定,对10t/h 以上锅炉年运行在4000小时以上的锅炉房,改造与建设时必须采用热电结合的要求,近年来有关部门着重对机组的参数、容量以及有关技术要求作了大量可行性比较和讨论。从热能利用及提高经济性等角度,曾确定了一些参数及技术要求,主要有:1.10t/h 锅炉采用中压参数即3.82MPa及450℃;2.20t/h 及35t/h 锅炉采用中压或次高压(即5.3MPa,485℃或450℃)两种参数;     

基于EBSILON的热电厂热电负荷分配优化研究

为优化热电厂热电负荷分配,提高热电厂运行热经济性,利用EBSILON软件建立某热电厂350和330 MW热电联产机组热力系统仿真模型和热经济性模型,根据抽汽点的蒸汽焓值进行热负荷计算,采用(火用)分析方法对热电联产机组进行能耗特性分析,得到两台机组在安全运行区间内的(火用)效率分布规律。通过遗传算法,研究不同热电负荷分配方式对热电厂热经济性的影响,进一步对热电厂典型日的热电负荷进行分配优化。结果表明：当机组供热流量达到最大值且电负荷为该供热流量下的最大值时,机组的(火用)效率达到最大值,对电负荷和热负荷进行分配优化的节能收益大于对单一因素优化;采用遗传算法优化热电负荷后,典型工况下全厂标准煤耗量降低1.75 t/h、发电标准煤耗率降低3.65 g/(kW·h)、(火用)效率提高0.49%;典型日全厂标准煤耗量降低35 t/d、发电标准煤耗率降低3.16 g/(kW·h)、(火用)效率提高0.41%。     

水泥厂附属电站装机方案探讨

干法水泥生产要消耗大量电能,在缺电地区,为确保生产线满负荷运行,除余热发电外,水泥厂附属电站还通过增加燃煤锅炉或机组的方式来提高自发电量。结合电力行业在小容量高参数方面取得的进展,提出当水泥厂自备电站火电与余热发电分开建设时,火电容量达50MW左右时,应考虑采用超高压机组。火电容量在25MW及以上时,应采用高温高压机组。火电容量小于25MW,应尽量采用高温高压或次高温高压参数,尽量避免采用中温中压参数。若火电容量小于10MW时,多炉一机方案较之于中温中压方案仍有一定优势,需具体情况具体分析。     

中小型热电厂节能技术改造

中温中压参数的热电厂,循环热效率低,经济性差。随煤炭价格的上涨,2004年,2005年出现了全行业性亏损。要实现节能降耗,降低生产成本,采用高参数的锅炉的汽轮发电机组进行技术改造,是一种比较可行的节能措施,并且经济性效果显著。     

垃圾焚烧电厂热电联产的经济性分析

合理利用垃圾资源进行热电联产,是节能减排、改善环境的有力措施。以某2×750 t·d^-1垃圾焚烧电厂为例,通过模型研究发现热电联产可以减少垃圾焚烧电厂的冷源损失,提高全厂热效率;利用一抽蒸汽进行热电联产可实现蒸汽品质的梯级利用,获得较高的经济效益;供热量为30 t·h^-1,垃圾热值由4185.9 kJ·kg^-1增加至8371.7 kJ·kg^-1时,发电量越多,供热能力越强,年热电联产经济效益由7822.76万元增加到14641.07万元;垃圾热值为8371.7 kJ·kg^-1,供热量从10 t·h^-1增加到60 t·h^-1时,垃圾焚烧电厂热效率从28.96%增加到48.50%,年经济效益从13602.74万元增加到15455.66万元。当该地区垃圾热值较高并具备供热条件时,实现垃圾热电联产具有较高的收益。     

带冷凝除湿的湿空气透平热电联产系统

建议了一种新的基于加湿和冷凝除湿混合循环的湿空气透平热电联产系统,可提高城市热电联产系统的发电和能源利用效率,实现燃料和热源的多样性,降低主机投资和装置回收周期。利用直接式除湿器进一步回收潜热和改善系统。基于节点能量平衡的热力性能分析方法,揭示了关键参数对系统性能影响的特性规律。分析表明:借助联合应用加湿和除湿过程,系统主机的优化压缩比可以低选,发电和热电效率相应提高,有利于实用、经济、环保地实现分布式热电联产节能工程。     

热电站节能设计

小型热电联产机组一般都是采用高温高压及以下参数,因此相比较于采用超超临界的大机组,有着先天性的劣势,大机组全厂发电效率可以达到40%以上,而热电站的发电效率通常只有28%左右。本文介绍了四种热电站优化设计工艺方案,用以提高热电站的全厂热效率,以达到节能的目标。     

污水厂热电联产工程效益分析

青岛某污水厂每天进水量约为14.5万t,该厂污水处理采用"中温厌氧消化+热电联产"工艺。文中通过对该厂设备正常运行数据,其中包括日处理污水量、污泥量、沼气产量、效益及发电量等进行了系统整理与分析,由于该污水厂采用厌氧消化技术,并通过回收发电机烟气余热和缸套水余热来加热消化池,该技术的应用不仅节约了该厂能源消耗,而且还提高了产气的稳定性。由于该厂沼气发电量为厂内自用,因此,该厂还节省了约22%的购电费用。     

COOLCEP (cool clean efficient power): A novel CO2-capturing oxy-fuel power system with LNG (liquefied natural gas) coldness energy utilization

A novel liquefied natural gas (LNG) fueled power plant is proposed, which has virtually zero CO₂ and other emissions and a high efficiency. The plant operates as a subcritical CO₂ Rankine-like cycle. Beside the power generation, the system provides refrigeration in the CO₂ subcritical evaporation process, thus it is a cogeneration system with two valued products. By coupling with the LNG evaporation system as the cycle cold sink, the cycle condensation process can be achieved at a temperature much lower than ambient, and high-pressure liquid CO₂ can be withdrawn from the cycle without consuming additional power. Two system variants are analyzed and compared, COOLCEP-S and COOLCEP-C. In the COOLCEP-S cycle configuration, the working fluid in the main turbine expands only to the CO₂ condensation pressure; in the COOLCEP-C cycle configuration, the turbine working fluid expands to a much lower pressure (near-ambient) to produce more power. The effects of some key parameters, the turbine inlet temperature and the backpressure, on the systems' performance are investigated. It was found that at the turbine inlet temperature of 900 °C, the energy efficiency of the COOLCEP-S system reaches 59%, which is higher than the 52% of the COOLCEP-C one. The capital investment cost of the economically optimized plant is estimated to be about 750 EUR/kWe and the payback period is about 8–9 years including the construction period, and the cost of electricity is estimated to be 0.031–0.034 EUR/kWh.     

Economic analysis of power generation from floating solar chimney power plant

Solar chimney thermal power technology that has a long life span is a promising large-scale solar power generating technology. This paper performs economic analysis of power generation from floating solar chimney power plant (FSCPP) by analyzing cash flows during the whole service period of a 100 MW plant. Cash flows are influenced by many factors including investment, operation and maintenance cost, life span, payback period, inflation rate, minimum attractive rate of return, non-returnable subsidy rate, interest rate of loans, sale price of electricity, income tax rate and whether additional revenue generated by carbon credits is included or not. Financial incentives and additional revenue generated by carbon credits can accelerate the development of the FSCPP. Sensitivity analysis to examine the effects of the factors on cash flows of a 100 MW FSCPP is performed in detail. The results show that the minimum price for obtaining minimum attractive rate of return (MARR) of 8% reaches 0.83 yuan (kWh)^?1 under financial incentives including loans at a low interest rate of 2% and free income tax. Comparisons of economics of the FSCPP and reinforced concrete solar chimney power plant or solar photovoltaic plant are also performed by analyzing their cash flows. It is concluded that FSCPP is in reality more economical than reinforced concrete solar chimney power plant (RCSCPP) or solar photovoltaic plant (SPVP) with the same power capacity.     

Efficiency improvement for geothermal power generation to meet summer peak demand

Geothermal power is an important part of New Zealand's renewable electricity supply due to its attractive cost and reliability. Modular type binary cycle plants have been imported and installed in various geothermal fields in New Zealand, with plans for further expansion. Power output of these plants deteriorates in the summer because plant efficiency depends directly on the geothermal resource and the ambient temperature. As these plants normally use air-cooled condensers, incorporating a water-augmented air-cooled system could improve the power output in summer thereby matching the peak air-conditioning demand. In this work, power generation for the Rotokawa plant was characterized using a similar plant performance and local weather. The improved performance was modelled for retrofit with a wet-cooling system. Maximum generation increase on the hottest day could be 6.8%. The average gain in power over the summer, November–February, was 1.5%, and the average gain for the whole year was 1%. With current binary unit generation capacity at the Rotokawa plant of 35 MW, investment in a water-augmented air-cooled system could provide 2 MW of peak generation on the hottest days. This investment in efficiency is found to compare favourably to other supply options such as solar PV, wind or gas.     

Thermoeconomic analysis of a novel zero-CO2-emission high-efficiency power cycle using LNG coldness

This paper presents a thermoeconomic analysis aimed at the optimization of a novel zero-CO₂ and other emissions and high-efficiency power and refrigeration cogeneration system, COOLCEP-S (Patent pending), which uses the liquefied natural gas (LNG) coldness during its revaporization. It was predicted that at the turbine inlet temperature (TIT) of 900 °C, the energy efficiency of the COOLCEP-S system reaches 59%. The thermoeconomic analysis determines the specific cost, the cost of electricity, the system payback period and the total net revenue. The optimization started by performing a thermodynamic sensitivity analysis, which has shown that for a fixed TIT and pressure ratio, the pinch point temperature difference in the recuperator, ΔT_p1, and that in the condenser, ΔT_p2 are the most significant unconstrained variables to have a significant effect on the thermal performance of novel cycle. The payback period of this novel cycle (with fixed net power output of 20 MW and plant life of 40 years) was 5.9 years at most, and would be reduced to 3.1 years at most when there is a market for the refrigeration byproduct. The capital investment cost of the economically optimized plant is estimated to be about 1000 $/kWe, and the cost of electricity is estimated to be 0.34–0.37 CNY/kWh (0.04 $/kWh). These values are much lower than those of conventional coal power plants being installed at this time in China, which, in contrast to COOLCEP-S, do produce CO₂ emissions at that.     

Simulation study of a large scale line-focus trough collector solar power plant in Greece

This paper deals with the technical feasibility and economic viability of a solar thermal power plant using parabolic trough collectors in Greece. The power plant is to be installed in the island of Rhodes and its power output will be 8.55 MW. Power plant simulation is carried out using TRNSYS software (STEC library) and economic issues of the project such as initial cost of investment, operation and maintenance (O&M) and energy costs will be analyzed. It was found that for the particular investment, considering a 75% of initial investment cost loan (with a 10-year period), the payback period will be approximately 13 years.     

Optimization of an atmospheric air volumetric central receiver system: Impact of solar multiple,storage capacity and control strategy

Portugal has a high potential for concentrated solar power and namely for atmospheric air volumetric central receiver systems (CRS). The solar multiple and storage capacity have a significant impact on the power plant levelized electricity cost (LEC) and their optimization and adequate control strategy can save significant capital for the investors. The optimized proposed volumetric central receiver system showed good performance and economical indicators.For Faro conditions, the best 4 MW_e power plant configuration was obtained for a 1.25 solar multiple and a 2 h storage. Applying control strategy #1 (CS#1) the power plant LEC is 0.234 €/kWh with a capital investment (CAPEX) of € 22.3 million. The capital invested has an internal rate of return (IRR) of 9.8%, with a payback time of 14 years and a net present value (NPV) of € 7.9 million (considering an average annual inflation of 4%). In the case of better economical indicators, the power plant investment can have positive contours, with an NPV close to € 13 million (annual average inflation of 2%) and the payback shortened to 13 years.     

Study of MW-scale biogas-fed SOFC-WGS-TSA-PEMFC hybrid power technology as distributed energy system: Thermodynamic,exergetic and thermo-economic evaluation

Advanced biogas power generation technology has been attracting attentions, which contributes to the waste disposal and the mitigation of greenhouse gas emissions. This work proposes and models a novel biogas-fed hybrid power generation system consisting of solid oxide fuel cell, water gas shift reaction, thermal swing adsorption and proton exchange membrane fuel cell (SOFC-WGS-TSA-PEMFC). The thermodynamic, exergetic, and thermo-economic analyses of this hybrid system for power generation were conducted to comprehensively evaluate its performance. It was found that the novel biogas-fed hybrid system has a gross energy conversion efficiency of 68.63% and exergy efficiency of 65.36%, indicating high efficiency for this kind of hybrid power technology. The market sensitivity analysis showed that the hybrid system also has a low sensitivity to market price fluctuation. Under the current subsidy level for the distributed biogas power plant, the levelized cost of energy can be lowered to 0.02942 $/kWh for a 1 MW scale system. Accordingly, the payback period and annual return on investment can reach 1.4 year and about 20%, respectively. These results reveal that the proposed hybrid system is promising and economically feasible as a distributed power plant, especially for the small power scale (no more than 2 MW).     

热电联产机组储热罐最佳容量的确定方法

为解决“风热冲突”下储热罐的容量选择问题,以热电联产机组整个采暖期为研究对象,引入特征日概念,对配置储热罐后的热电机组建立了逐小时的运行模型。分别以机组深度调峰空间的增量、全年总收益和10年净现值为目标函数,寻找储热罐容量的最优值。结果表明,热负荷越高储热罐的最佳容量也越大,同时机组配置储热罐后所能获得的深度调峰空间也越大;不考虑初投资时,以全年总收益为目标的储热罐最优容量约为820 MW;在考虑初投资后,以10年净现值为目标的储热罐最优容量约为430 MW,容量几乎减半。     

光伏电站的投资前景分析

在世界各国对太阳能光伏发电鼓励政策引导下,近年来太阳能光伏发电产业呈现出快速发展的势头。文章就建立光伏电站所涉及的电站成本、相关政策和市场状况问题进行了研究分析。在不考虑政府财政补贴的情况下,2008年投资光伏电站每年平均损失115.5万元/MW,当前投资光伏电站每年可平均获得利润33万元/MW。在国内太阳能电站的收益率水平迅速提升的形势下,预计未来5年将是我国太阳能电站投资的黄金时期,建议政府和相关企业抓住机遇,加大光伏电站的投入和建设。