Simulation analysis of a repowered double fuel CHP plant including a non‐evaporative heat recovery boiler

A repowering analysis of a conventional, coal‐fired industrial combined heat and power (CHP) plant by means of a gas turbine (GT) and heat recovery boiler (HRB) has been taken into consideration. The existing system, operating in one of the Polish chemical factories consists of coal‐fired boilers, back‐pressure extraction turbines, condensing turbines and steam‐fed district heat exchangers. Two variants of modernization have been proposed and examined from the thermodynamic, environmental protection and economical points of view. The first one includes HRB for preheating the boiler feed water, condensate, and district water, while the steam turbine (ST) system and coal boilers work without any structural changes. The other advanced variant introduces live steam superheaters to HRB. The coal‐fired boilers, in this light, supply only saturated steam (which is introduced into HRB), so they have to be readjusted by replacing the existing superheaters with convective vaporizers for proper flue gas cooling. Such a scheme ensures a considerable reduction of exergy losses in HRB and therefore leads to deeper flue gas cooling and a decrease of coal consumption for the assumed process steam and district heat demands. Heat and process steam demand duration curves for a typical year of operation of the plant have been adapted as input data. The mathematical model of the whole CHP plant has been built on GateCycle and Visual Basic software. The model includes design and off design analyses of boilers, steam and gas turbines and also takes into account shut‐down necessities, concerning machines during their operation outside the acceptable area of their key parameters (e.g. the minimum steam flow in the condensing section of the turbines from the point of view of rotor cooling). The computation was run many times for different sets of input data, read from the demand duration curves. Finally, the yearly values of solid and gaseous fuel consumption, as well as electricity production have been calculated. Both proposed variants of the repowered CHP system have been compared with the existing plant by means of the incremental cumulative economy of chemical energy and pollutant emission. An approximate classical economy analysis net present value (NPV), discounted pay back (DPB) has also been carried out. The whole computation has been replayed for several market GT models. The results obtained lead to the conclusion that repowering of a coal‐fired plant by means of a GT and HRB is a very effective way to improve the thermodynamic and environmental protection aspects of power and heat generation. The introduction of the live steam superheater into HRB provides additional advantages in these fields. The economic results indicate DPBs from 3 to 11 years, depending on the situation at the electricity and fuel markets. Copyright © 2004 John Wiley & Sons, Ltd.     

二次再热超临界机组热力系统的全方位线性分析法

建立了计算锅炉吸热量、汽轮机作功、凝汽器放热量的线性模型，并通过分析抽汽和各种附加汽水成分对热力系统质量及热量平衡的作用和影响，得出二次再热超临界机组质热平衡关系的快速建模方法及各种附加成分的线性分析方法，用线性方法实现了对二次再热超临界机组锅炉吸热量、汽轮机功率及凝汽器放热量的全面分析与计算。     

火电厂空气预热器旁路余热利用系统经济性分析

为实现对某电厂空气预热器旁路烟气余热利用系统的经济性综合评价,针对采用空气预热器旁路的机组提出了一种锅炉效率检测和计算方法,将空气预热器旁路传递的烟气热量作为锅炉热损失的一部分,确立了一套以试验检测为基础,结合理论推导计算的评价方法,定量分析了空气预热器旁路余热利用系统运行对锅炉效率、汽轮机热耗和厂用电率的影响,并开展了相应的检测试验。试验结果表明:某电厂空气预热器旁路烟气余热利用系统在满负荷工况下可降低供电煤耗2.80 g/(kW·h),在低负荷和环境温度较低的冬季工况经济性会受到较大影响。     

Engineering design and exergy analyses for combustion gas turbine based power generation system

This paper presents the engineering design and theoretical exergetic analyses of the plant for combustion gas turbine based power generation systems. Exergy analysis is performed based on the first and second laws of thermodynamics for power generation systems. The results show the exergy analyses for a steam cycle system predict the plant efficiency more precisely. The plant efficiency for partial load operation is lower than full load operation. Increasing the pinch points will decrease the combined cycle plant efficiency. The engineering design is based on inlet air-cooling and natural gas preheating for increasing the net power output and efficiency. To evaluate the energy utilization, one combined cycle unit and one cogeneration system, consisting of gas turbine generators, heat recovery steam generators, one steam turbine generator with steam extracted for process have been analyzed. The analytical results are used for engineering design and component selection.     

Efficiency improvement and superiority of steam injection in gas turbines

An open cycle gas turbine with a heat exchanger and its modifications have been studied. These modifications include the combinations of the gas turbine with a steam injection system and the gas turbine with a closed cycle steam turbine. The steam is generated by a waste heat boiler. It was found that in both cases the efficiency and the net output of the gas turbine increased considerably, of the order of 20–40%. In order to define the superiority regions of the systems studied on various ranges of power output, an economic analysis per unit power has been done. For short duration, intermittent type of operation the steam injection was found superior. Above this mode of operation, the operational modes of electric base and continuous were covered by the gas turbine combined with the steam turbine.     

三压再热汽水系统IGCC的设计工况和变工况性能

以三压再热式汽水系统ＩＧＣＣ（整体煤气化燃气－蒸汽联合循环）为研究对象组成了整体空分ＩＧＣＣ系统方案,建立了气化炉,净化系统,燃气轮机,空分装置,余热锅炉,汽轮机各组成部件的数学模型,对ＩＧＣＣ系统的设计工况和变工况特性进行计算,分析了煤气轮机采用不同调节规律和汽轮机采用不同运行方式时对系统变工况性能的影响并提出了合理的运行方式。     

火电机组烟水复合回热系统节能解析

针对采用新型烟气余热深度利用技术的烟水复合回热系统,以600 MW超临界汽轮机组为例,运用热量平衡、火用平衡两种手段进行了节能分析。优化系统设置了空预器烟气旁路,布置高、低压换热器加热给水,设置回收低品位余热的前置空预器。通过定功率全系统热力计算表明,优化系统深度利用锅炉排烟余热,主蒸汽流量减少,供电标准煤耗率减小5.13 g/(k W·h)。优化系统锅炉传热火用损失、回热加热器火用损失减少。机组总火用损失减少,效率提高。工程应用表明,改造后机组实际供电标准煤耗降低了6.78 g/(k W·h)。     

Thermodynamic analysis of an LNG fuelled combined cycle power plant with waste heat recovery and utilization system

This paper has proposed an improved liquefied natural gas (LNG) fuelled combined cycle power plant with a waste heat recovery and utilization system. The proposed combined cycle, which provides power outputs and thermal energy, consists of the gas/steam combined cycle, the subsystem utilizing the latent heat of spent steam from the steam turbine to vaporize LNG, the subsystem that recovers both the sensible heat and the latent heat of water vapour in the exhaust gas from the heat recovery steam generator (HRSG) by installing a condensing heat exchanger, and the HRSG waste heat utilization subsystem. The conventional combined cycle and the proposed combined cycle are modelled, considering mass, energy and exergy balances for every component and both energy and exergy analyses are conducted. Parametric analyses are performed for the proposed combined cycle to evaluate the effects of several factors, such as the gas turbine inlet temperature (TIT), the condenser pressure, the pinch point temperature difference of the condensing heat exchanger and the fuel gas heating temperature on the performance of the proposed combined cycle through simulation calculations. The results show that the net electrical efficiency and the exergy efficiency of the proposed combined cycle can be increased by 1.6 and 2.84% than those of the conventional combined cycle, respectively. The heat recovery per kg of flue gas is equal to 86.27 kJ s^?1. One MW of electric power for operating sea water pumps can be saved. The net electrical efficiency and the heat recovery ratio increase as the condenser pressure decreases. The higher heat recovery from the HRSG exit flue gas is achieved at higher gas TIT and at lower pinch point temperature of the condensing heat exchanger. Copyright © 2006 John Wiley & Sons, Ltd.     

Analysis of parameters affecting the performance of gas turbines and combined cycle plants with vapor absorption inlet air cooling

The integration of an aqua‐ammonia inlet air‐cooling scheme to a cooled gas turbine‐based combined cycle has been analyzed. The heat energy of the exhaust gas prior to the exit of the heat recovery steam generator has been chosen to power the inlet air‐cooling system. Dual pressure reheat heat recovery steam generator is chosen as the combined cycle configuration. Air film cooling has been adopted as the cooling technique for gas turbine blades. A parametric study of the effect of compressor–pressure ratio, compressor inlet temperature, turbine inlet temperature, ambient relative humidity, and ambient temperature on performance parameters of plants has been carried out. It has been observed that vapor absorption inlet air cooling improves the efficiency of gas turbine by upto 7.48% and specific work by more than 18%, respectively. However, on the adoption of this scheme for combined cycles, the plant efficiency has been observed to be adversely affected, although the addition of absorption inlet air cooling results in an increase in plant output by more than 7%. The optimum value of compressor inlet temperature for maximum specific work output has been observed to be 25 °C for the chosen set of conditions. Further reduction of compressor inlet temperature below this optimum value has been observed to adversely affect plant efficiency. Copyright © 2013 John Wiley & Sons, Ltd.     

燃机电厂9F型机组热电负荷优化分配研究

电厂热电负荷优化分配是指在全厂总调度负荷下,根据各机组的热力性能确定各机组应承担的热电负荷,使得全厂效益最大或能耗最小的一种最优化问题.不同于燃煤热电厂,燃机电厂9F型机组由于设计为燃气轮机加蒸汽轮机的组合方式运行,因此在联合循环热力性能模型建立上较为复杂.提出了将余热锅炉新蒸汽参数作为中间变量,建立了机组天然气燃料消耗与电负荷、热负荷之间的关系模型,确定了优化计算的目标函数和边界约束条件,并采用非线性规划方法求解.模拟与实际运行结果均表明,该优化分配方法能有效降低燃机电厂燃料消耗水平,可以为同类型燃机电厂热电负荷优化分配提供参考.     

Comparative exergoeconomic analyses of the integration of biomass gasification and a gas turbine power plant with and without fogging inlet cooling

Inlet cooling is effective for mitigating the decrease in gas turbine performance during hot and humid summer periods when electrical power demands peak, and steam injection, using steam raised from the turbine exhaust gases in a heat recovery steam generator, is an effective technique for utilizing the hot turbine exhaust gases. Biomass gasification can be integrated with a gas turbine cycle to provide efficient, clean power generation. In the present paper, a gas turbine cycle with fog cooling and steam injection, and integrated with biomass gasification, is proposed and analyzed with energy, exergy and exergoeconomic analyses. The thermodynamic analyses show that increasing the compressor pressure ratio and the gas turbine inlet temperature raises the energy and exergy efficiencies. On the component level, the gas turbine is determined to have the highest exergy efficiency and the combustor the lowest. The exergoeconomic analysis reveals that the proposed cycle has a lower total unit product cost than a similar plant fired by natural gas. However, the relative cost difference and exergoeconomic factor is higher for the proposed cycle than the natural gas fired plant, indicating that the proposed cycle is more costly for producing electricity despite its lower product cost and environmental impact.     

饱和蒸汽减温在燃机余热锅炉的应用

介绍了燃气－蒸汽联合循环电站余热锅炉过热蒸汽调温的一种方法－自身饱和蒸汽减温。对余热锅炉自身饱和蒸汽减温系统的设计进行了分析,指出了实际应用中应该注意的问题。     

Environmental assessment and extended exergy analysis of a “zero CO2 emission”, high-efficiency steam power plant

Aim of this paper is to analyze the performance of an innovative high-efficiency steam power plant by means of two “life cycle approach” methodologies, the life cycle assessment (LCA) and the “extended exergy analysis” (EEA).

The plant object of the analysis is a hydrogen-fed steam power plant in which the H₂ is produced by a “zero CO₂ emission” coal gasification process (the ZECOTECH^© cycle). The CO₂ capture system is a standard humid-CaO absorbing process and produces CaCO₃ as a by-product, which is then regenerated to CaO releasing the CO₂ for a downstream mineral sequestration process.

The steam power plant is based on an innovative combined-cycle process: the hydrogen is used as a fuel to produce high-temperature, medium-pressure steam that powers the steam turbine in the topping section, whose exhaust is used in a heat recovery boiler to feed a traditional steam power plant.

The environmental performance of the ZECOTECH^© cycle is assessed by comparison with four different processes: power plant fed by H₂ from natural gas steam reforming, two conventional coal- and natural gas power plants and a wind power plant.     

AE94.3A型燃气轮机进气冷却的应用可行性研究

对AE94.3A型燃气轮机燃气-蒸汽联合循环热力系统平衡进行研究进而发现,与同类型、同等级不同型号机组相比,AE94.3A型联合循环机组余热锅炉的排烟温度较高,排烟余热仍有进一步利用的空间。通过设计优化,扩大省煤器受热面,回收烟气余热加热给水,驱动热水型溴化锂制冷机制冷,用于机组满负荷调峰时的压气机进气冷却或厂房及办公区域空调供冷,对改善燃气轮机联合循环的运行性能,实现能源梯级利用,提高能源利用率和机组经济性运行起到了很大作用。     

湿法烟气脱硫系统对发电机组运行的影响研究

在连州电厂石灰石/石膏湿法烟气脱硫系统上进行了FGD系统对发电机组运行影响的研究,主要分析了FGD系统的运行对锅炉炉膛负压、尾部烟道腐蚀、工业水系统、汽机运行的影响以及脱硫石膏与电厂灰渣水混排对现有排放系统的影响。研究结果对湿法烟气脱硫系统的设计,运行有很好的参考价值。     

Analysis of biomass-residue-based cogeneration system in palm oil mills

Palm oil mills in Malaysia operate on cogeneration system using biomass residue as fuel in the boiler. The boiler produces high pressure and temperature steam which expands in a backpressure steam turbine and produces enough electric power for the internal needs of the mill. The exhaust steam from the turbine goes to an accumulator which distributes the steam to various processes in the mill.The study were made on seven palm oil mills in the Perak state in Malaysia. The primary objectives of the study are to determine boiler and turbine efficiencies, energy utilization factor, oil extraction rate and heat/power ratio for various palm oil mills working under similar conditions and adopting same processes. The palm oil industry is one of those rare industries where very little attempt is made to save energy. The energy balance in a typical palm oil mill is far from optimum and there is considerable scope for improvement. Bench-marking is necessary for the components in the mill. Energy-use bench-marking can give an overview of energy performance of the mills. The calculations were done to get net gain in power when back pressure turbine is replaced by a condensing turbine.It was found that the boiler and turbine have low thermal efficiencies compared to conventional ones used in power plants due to non-homogeneity and non-uniform quality of the fuel. The extraction rate was around 0.188. The use of condensing turbine increase the power output by 60% and the utilization factor was found to be 65% for the cogeneration system.     

炼油厂热动系统优化与节能改造

介绍了某炼油厂热能动力系统节能优化配置,分析了汽轮机低真空供暖与炼油工艺装置中低温热源间的联合热利用改造措施,采用新增机组实现对蒸汽使用的弹性调节;合理利用凝汽潜热。经改造及低温热联合利用节约了能源,效益显著。     

A thermodynamic analysis of a biogas-fired integrated gasification steam injected gas turbine (BIG/STIG) plant

A thermodynamic analysis considering both the first and the second laws of thermodynamics has been made on a 53 MW (net) biogas-fired integrated gasification steam injected gas turbine (BIG/STIG) plant. The energy utilization diagrams (EUDs) for the plant and for the reaction subsystems have also been considered, revealing both problems and potentials for improvement. The analysis indicates a thermal efficiency of about 41% (power based) and 45% (power and recovered heat based) but that the exergy loss in the combustion chamber is largest at about 79% of the total system exergy loss.     

Thermo‐Economic Analysis and Multiobjective Optimization of Dual Pressure Combined Cycle Power Plant with Supplementary Firing

The heat recovery steam generator (HRSG) and duct burner are parts of a combined cycle which have considerable effect on the steam generation. The effect of the gas turbine, duct burner and HRSG on power generation is investigated to reduce exergy destruction and power loss in the gas turbine. The results show that with an increase in duct burner flow rate, pressure loss in the recovery boiler increases, steam generation increases on the HP side while it decreases on the LP side. With a reduction in the HP pinch point, thermal recovery increases while the LP pinch point does not have a significant effect. Then, power loss due to pressure drop in the gas turbine and the electricity cost are considered as two objective functions for optimization. Finally, the sensitivity analysis on ambient temperature, compressor pressure ratio, fuel lower heating value, duct burner fuel rate, condenser pressure and main pressure are performed and results are reported. It is concluded that with an increment in compressor pressure ratio, the duct burner flow rate and consequently steam generation increases while electricity cost decrease.     

冷热电三联供系统的优化研究

冷热电联供系统主要应用于大型集中性供能系统中。作为分布式能源的一种,冷热电联供系统具有节约能源、改善环境、提高电力综合效益的优势。一般情况下,三联供系统是以天然气为燃料带动燃气轮机、微燃机或内燃机发电机等燃气发电设备运行,产生的电力供应用户的电力需求,系统发电后排出的余热通过余热回收利用设备(余热锅炉或者余热直燃机等)向用户供热、供冷。通过这种方式提高整个系统的一次能源利用率,实现能源的梯级利用,还可以提供并网电力作能源互补,经济收益和效率均得以提升。研究较为常见的燃气轮机中的一种蒸汽型吸收式冷热电联产系统,对不同配置方式和运行方式进行横向与纵向交叉比较,以完成系统优化研究。