Gas turbine turbocharged by a steam turbine: a gas turbine solution increasing combined power plant efficiency and power

A new design of a combined-cycle gas turbine power plant CCGT with sequential combustion that increases efficiency and power output in relation to conventional CCGT plants is studied. The innovative proposal consists fundamentally in using all the power of the steam turbine to turbocharge the gas turbine. A computer program has been developed to carry out calculations and to evaluate performance over a wide range of operating conditions. The obtained results are compared with those of combined cycles where the gas turbines are not turbocharged and the gas and the steam turbines have independent power exits; the advantages of the new design are stated.     

Energy and exergy analysis of steam cooled reheat gas–steam combined cycle

This paper deals with parametric energy and exergy analysis of reheat gas–steam combined cycle using closed-loop-steam-cooling. Of the blade cooling techniques, closed-loop-steam-cooling has been found to be superior to air-film cooling. The reheat gas–steam combined cycle plant with closed-loop-steam-cooling exhibits enhanced thermal efficiency (around 62%) and plant specific work as compared to basic steam–gas combined cycle with air-film cooling as well as closed-loop-steam cooling. Further, with closed-loop-steam-cooling, the plant efficiency, reaches an optimum value in higher range of compressor pressure ratio as compared to that in film air-cooling. It has also been concluded that reheat pressure is an important design parameter and its optimum value gives maximum plant efficiency.Component-wise inefficiencies of steam cooled-reheat gas–steam combined cycle based on the second-law-model (exergy analysis) have been found to be the maximum in combustion-chamber (≈30%), followed by that in gas turbine (≈4%).     

燃气轮机联合循环电厂孤网运行浅析

为保障电网安全,电网提出当省网220kV回路故障时,由联合循环电厂独立承担局部地区供电任务。本文是对联合循环机组正常运行时,如果电网系统突发故障,联合循环电厂如何调节,才能使局部供电稳定,在技术方面进行探讨。     

Combining the nuclear power plant steam cycle with gas turbines

Nuclear steam power plants (NPP) are characterized by low efficiency, compared to steam power plants using fossil fuels. This is due to the relatively low temperature and pressure-throttling conditions of the NPP compared to those using fossil fuel. The light water pressurized water reactor (LW PWR) commercially known as AP600 was suggested for Kuwait cogeneration power desalting plant (CPDP). It has 600 MW nominal power capacity and 33% overall efficiency. Meanwhile, the Kuwaiti Ministry of Electricity and Water (MEW) installed plenty of gas turbines (GTs) to cover the drastic increase in the peak electrical load during the summer season. Combining some of these GTs with the AP600 can increase the capacity and efficiency of the combined plant, compared to either the GT open cycle or the NPP separate plants. This paper investigates the feasibility of utilizing the hot gases leaving the GT to superheat the steam leaving the steam generator of the AP600 NPP, as well as heating the feed water returning to the steam generator of the NPP condenser. This drastically increases the power output and the efficiency of the NPP. Detailed modifications to the NPP power cycle and the resulting enhancement of its performance are presented.     

利用燃气—蒸汽联合循环改造老电厂

利用燃气－蒸汽联合循环对老电厂进行改造,能够提高能源的综合使用率,降低能耗,并有效利用老电厂的现有设备,可以减少投资并见效快,文章对利用燃气－蒸汽联合循环对老电厂进行改造的主要方式和热效率进行了分析。     

Optimization of heat recovery steam generators for combined cycle gas turbine power plants

The heat recovery steam generator (HRSG) is one of the few components of combined cycle gas turbine power plants tailored for each specific application. Any change in its design would directly affect all the variables of the cycle and therefore the availability of tools for its optimization is of the greatest relevance. This paper presents a method for the optimization of the HRSG based on the application of influence coefficients. The influence coefficients are a useful mathematical tool in design optimization problems. They are obtained after solving the equations of the system through the Newton–Raphson method. The main advantage of the proposed method is that it permits a better understanding of the influence of the design parameters on the cycle performance. The study of the optimization of the distribution of the boiler area between its different components is presented as an example of the proposed technique.     

Thermo-environmental analysis of an open cycle gas turbine power plant with regression modeling and optimization

In this paper, a gas turbine cycle is modeled to investigate the effects of important operating parameters like compressor inlet temperature (CIT), turbine inlet temperature (TIT) and pressure ratio (PR) on the overall cycle performance and CO₂ emissions. Such effects are also investigated on the exergy destruction and exergy efficiency of the cycle components. Furthermore, multiple polynomial regression models are developed to correlate the response variables (performance characteristics) and predictor variables (operating parameters). The operating parameters are then optimized. According to the results, operating parameters have a significant effect on the cycle performance and CO₂ emissions. The largest exergy destruction is found in the combustion chamber with lowest exergy efficiency. The regression models have appeared to be a good estimator of the response variables. The optimal operating parameters for maximum performance have been determined as 288 K for CIT, 1600 K for TIT and 23.2 for PR.     

联合循环电厂汽轮机供热运行的若干问题

国内某联合循环电厂由于汽轮机缺乏非设计工况下抽汽供热运行经验且需要参与电网调峰,经过对联合循环机组特性分析和现场运行数据的整理、优化,在保证机组安全的前提下,确定了汽轮机供热量和机组调峰能力,为指导运行人员操作和确定机组电网调峰能力提供了依据。     

生物质气化的注蒸汽燃气轮机循环

简述了生物质的特点和对环境的影响及STIG循环的特点,重点从BIG/STIG循环系统匹配的角度,阐述了生物质气化发电系统中气化炉、净化系统及燃气轮机三部分的特点及要求,最后指出我国应该大力发展生物质气化发电技术,并提出一些建议。     

Integration of steam turbine controls into power plant systems

The unique control and protection requirements of steam turbines are described, and the concept of a unit control system, which by itself is capable of starting, loading, and unloading, as well as protecting, a steam turbine through all operational phases, is introduced. The unit control then interfaces to the plant control at a level where the speed of response and degree of security of a plantwide network is acceptable for the turbine. Examples of unit controls for different types of turbines are given, together with methods for interfacing to plant control systems     

Analysis of a gas turbine and steam turbine combined cycle with liquefied hydrogen as fuel

The performances of a combined cycle driven by the liquid hydrogen are discussed. The cycle consists of a gas turbine with a pre-cooler system and a steam turbine heated by the exhaust energy of gas turbine. The liquid hydrogen has not only chemical but cryogenic exergy. The latter is about 10% of the total exergy and is converted to the useful work through the pre-cooling system and an auxiliary hydrogen turbine. The specific output and thermal efficiency of the combined cycle are much higher than those of a simple cycle gas turbine, but in order to operate the combined cycle successfully, it is necessary to check the pinch point which may take place in the boiling process which is heated by the exhaust energy of the gas turbine.     

Thermoeconomic optimization method as design tool in gas–steam combined plant realization

In modern power plants design, not only high performances but also low capital investments have to be assured so that the final product proposed on the market could be competitive. Starting from this concept, in this work, we have realized a tool for a thermoeconomic evaluation and optimization of thermal power plants which could give solutions to problems connected with the design of real systems.

The model, using three programs and a set of cost correlations (obtained from collaboration with Nuovo Pignone–General Electric), can estimate the realization costs of a combined power plant as a function of the constructive and operation parameters. A test to verify the capacity of our model has been performed by simulating an existing plant. The results seem very good, and this tool will be soon used also in the industry.     

湿化燃气轮机循环的性能分析

能源危机和环境污染的问题使人们对能源利用效率和环保的要求日益增加,同时经济的快速发展也使人们对电能的需求量越来越大。据国际能源协会(IEA)预测,电能的消耗将以平均每年2·4%的速度增长,因此效率高、比功输出大、对环境污染少成为目前发电技术所努力追求的目标。随着分布     

燃气-蒸汽联合循环电站机组配置及选型分析

对联合循环电站燃气轮机选型、蒸汽系统的选择、余热锅炉和汽轮机选型、机组轴系配置、动力岛布置、主要辅助设备的选择等方面进行了分析研究,为联合循环电站的设计和研究方向提供了建议。     

Optimization of heat recovery steam generator through exergy analysis for combined cycle gas turbine power plants

This paper proposes a new approach to finding the optimum design parameters of the heat recovery steam generator (HRSG) system to maximize the efficiency of the steam turbine (bottom) cycle of the combined cycle power plant (CCPP), but without performing the bottom cycle analysis. This could be achieved by minimizing the unavailable exergy (the sum of the destroyed and the lost exergies) resulted from the heat transfer process of the HRSG system. The present approach is relatively simple and straightforward because the process of the trial-and-error method, typical in performing the bottom cycle analysis for the system optimization, could be avoided. To demonstrate the usefulness of the present method, a single-stage HRSG system was chosen, and the optimum evaporation temperature was obtained corresponding to maximum useful work for given conditions of water and gas temperatures at the inlets of the HRSG system. Results show that the optimum evaporation temperature obtained based on the present exergy analysis appears similar to that based on the bottom cycle analysis. Also shown is the dependency of number of transfer unit (NTU) on the evaporation temperature, which is another important factor in determining the optimum condition when the construction cost is taken into account in addition to the operating cost. The present approach turned out to be a powerful tool for optimization of the single-stage HRSG systems and can easily be extended to multi-stage systems. Copyright © 2008 John Wiley & Sons, Ltd.     

Maximum overall efficiency for a solar‐driven gas turbine power plant

A general model for an irreversible solar‐driven Brayton multi‐step heat engine is presented. The model incorporates an arbitrary number of turbines (N_t) and compressors (N_c) and the corresponding reheating and intercooling processes; thus, the solar‐driven Ericsson cycle is a particular case where N_t, N_c → ∞. For the solar collector, we assume linear heat losses, and for the Brayton multi‐step cycle, we consider irreversibilities arising from the non‐ideal behavior of turbines and compressors, pressure drops in the heat input and heat release, heat leakage through the plant to the surroundings, and non‐ideal couplings of the working fluid with the external heat reservoirs. We obtain the collector temperatures at which maximum overall efficiency η_max is reached as a function of the thermal plant pressure ratio, and a detailed comparison for several plant configurations is given. This maximum efficiency is obtained in two cases: when only internal irreversibilities are considered and when both internal and external irreversibilities (which corresponds to the fully irreversible realistic situation) are simultaneously taken into account. Differences between both situations are stressed in detail. In the fully irreversible realistic case, it is possible to perform an additional optimization with respect to the pressure ratio, . In particular, this double optimization leads to a valuable increase in efficiency (between 34% and 65%) for a plant with two turbines and two compressors compared to the simple solar‐driven one‐turbine one‐compressor Brayton engine. Copyright © 2012 John Wiley & Sons, Ltd.     

Performance of a water gas shift pilot plant processing product gas from an industrial scale biomass steam gasification plant

In this paper, the performance of a commercial Fe/Cr based catalyst for the water gas shift reaction was investigated. The catalyst was used in a water gas shift pilot plant which processed real product gas from a commercial biomass steam gasification plant with two different qualities: extracted before and extracted after scrubbing with a rapeseed methyl ester gas scrubber. The performance of the WGS pilot plant regarding these two different gas qualities was investigated. For this reason, extensive chemical analyses were carried out. CO, CO₂, CH₄, N₂, O₂, C₂H₆, C₂H₄, and C₂H₂ and H₂S, COS, and C₄H₄ S were measured. In addition, GCMS tar and NH₃ analyses were performed. Furthermore, the catalyst's activity was observed by measuring the temperature profiles along the reactors of the water gas shift pilot plant. During the 200 h of operation with both product gas qualities, no catalyst deactivation could be observed. A CO conversion up to 93% as well as a GCMS tar reduction (about 28%) along the water gas shift pilot plant was obtained. Furthermore, a specific H₂ production of 63 g H₂ per kg biomass (dry and ash free) was reached with both product gas qualities. No significant performance difference could be observed.     

Analytical method for evaluation of gas turbine inlet air cooling in combined cycle power plant

Gas turbine inlet air cooling technologies (GTIAC), mainly including chilling with LiBr/water absorption chiller and fogging as well, are being used during hot seasons to augment the power output. To evaluate the general applicability of inlet air cooling for gas–steam combined cycle power plant (GTCCIAC), parameters such as efficiency ratio, profit ratio and relative payback period were defined and analyzed through off-design performances of both gas turbine and inlet air cooling systems. An analytical method for applicability evaluation of GTCCIAC with absorption chiller (inlet chilling) and saturated evaporative cooler (inlet fogging) was presented. The applicability study based on typical off-design performances of the components in GTCCIAC shows that, the applicability of GTCCIAC with chilling and fogging depends on the design economic efficiency of GTCC power plant. In addition, it relies heavily on the climatic data and the design capacity of inlet air cooling systems. Generally, GTCCIAC is preferable in the zones with high ambient air temperature and low humidity. Furthermore, it is more appropriate for those GTCC units with lower design economic efficiency. Comparison of the applicability between chilling and fogging shows that, inlet fogging is superior in power efficiency at t_a = 15–20 °C though it gains smaller profit margin than inlet chilling. GTCC inlet chilling with absorption chiller is preferable in the zones with t_a > 25 °C and RH > 0.4.     

从地域角度看燃气轮机发电在我国的发展及选型

把我国按地理位置分为六个大区,对每个大区从人口、经济、资源、环境污染等多方面进行综合评价。结合利用GT—PRO对采用不同级别燃气轮机的发电系统进行经济性分析,得出在未来一段时间内,基于F级燃气轮机联合循环仍将是我国华北、东北、东南沿海等大部份地区的首选燃机发电技术、中小型热电冷联产系统也将是燃气轮机应用的一个可行途径的结论。从长远来看,在富煤地区发展以燃气轮机发电为核心的煤基多联产系统有着更大的潜力。     

Improved load control for a steam cycle combined heat and power plant

The problem of optimum load control of steam power plants has been dealt within many technical papers during the last decades. Deregulation of the power markets and close to the (bio-) fuel source thinking has lead to a trend of small scale combined heat and power plants. These plants are usually operated according to the heat demand and therefore they spend a significant time on partial load. The load control of such plants is in general done by partial arc control. This work applies a hybrid control strategy, which is a combination of partial arc control and sliding pressure control. The method achieves further improvement in performance at partial load. Hybrid control itself is not novel and has earlier been used on traditional coal-fired condensing plants. This has, to the author's knowledge, not earlier been applied on combined heat and power plants. The results show that there is a potential for improved electricity production at a significant part of the load range.