A Gas Turbine Propulsion Plant With the Capability to Provide Steam for Both Injection and Aircraft Catapults

Author(s):  
Xueyou Wen ◽  
Yingxin Wei ◽  
Jierong Jin ◽  
Zhen Fu

Proposed in this paper is a novel propulsion system. On the basis of a gas turbine Brayton cycle a Rankine regenerative cycle was set up in parallel, which by utilizing the waste heat of the gas turbine exhaust gas is able to flexibly supply steam for gas turbine steam injection and for aircraft catapults. Thus brought forth is a gas turbine propulsion plant with a dual-purpose steam supply, which can well be suited for use on board an aircraft carrier. The propulsion plant under discussion has the inherent merits of a steam injected gas turbine cycle, but the additional new feature of steam supply for aircraft catapults significantly enhances the advantages of the propulsion plant as a whole. With a medium-sized aircraft carrier being selected as an example a comprehensive comparison has been conducted of four types of propulsion power plants, including a gas turbine propulsion plant with the capability to supply steam for both gas turbine steam injection and aircraft catapults.

Author(s):  
Carlo M. Bartolini ◽  
Danilo Salvi

The steam generated through the use of waste heat recovered from a steam injection gas turbine generally exceeds the maximum mass of steam which can be injected into steam injection gas turbine. The ratio between the steam and air flowing into the engine is not more than 10–15%, as an increase in the pressure ratio can cause the compressor to stall. Naturally, the surplus steam can be utilized for a variety of alternative applications. During the warmer months, the ambient temperature increases and results in reduced thermal efficiency and electrical capacity. An inlet air cooling system for the compressor on a steam injection gas turbine would increase the rating and efficiency of power plants which use this type of equipment. In order to improve the performance of steam injection gas turbines, the authors investigated the option of cooling the intake air to the compressor by harnessing the thermal energy not used to produce the maximum quantity of steam that can be injected into the engine. This alternative use of waste energy makes it possible to reach maximum efficiency in terms of waste recovery. This study examined absorption refrigeration technology, which is one of the various systems adopted to increase efficiency and power rating. The system itself consists of a steam injection gas turbine and a heat recovery and absorption unit, while a computer model was utilized to evaluate the off design performance of the system. The input data required for the model were the following: an operating point, the turbine and compressor curves, the heat recovery and chiller specifications. The performance of an Allison 501 KH steam injection gas plant was analyzed by taking into consideration representative ambient temperature and humidity ranges, the optimal location of the chiller in light of all the factors involved, and which of three possible air cooling systems was the most economically suitable. In order to verify the technical feasibility of the hypothetical model, an economic study was performed on the costs for upgrading the existing steam injection gas cogeneration unit. The results indicate that the estimated pay back period for the project would be four years. In light of these findings, there are clear technical advantages to using gas turbine cogeneration with absorption air cooling in terms of investment.


Author(s):  
A. Hofstädter ◽  
H. U. Frutschi ◽  
H. Haselbacher

Steam injection is a well-known principle for increasing gas turbine efficiency by taking advantage of the relatively high gas turbine exhaust temperatures. Unfortunately, performance is not sufficiently improved compared with alternative bottoming cycles. However, previously investigated supplements to the STIG-principle — such as sequential combustion and consideration of a back pressure steam turbine — led to a remarkable increase in efficiency. The cycle presented in this paper includes a further improvement: The steam, which exits from the back pressure steam turbine at a rather low temperature, is no longer led directly into the combustion chamber. Instead, it reenters the boiler to be further superheated. This modification yields additional improvement of the thermal efficiency due to a significant reduction of fuel consumption. Taking into account the simpler design compared with combined-cycle power plants, the described type of an advanced STIG-cycle (A-STIG) could represent an interesting alternative regarding peak and medium load power plants.


Author(s):  
Roberto Carapellucci ◽  
Lorena Giordano

Repowering existing power plants represents a potential route to meet the increasing energy demand, in a context of more and more stringent environmental regulations, hindering the construction of new facilities. Conventionally, repowering is operated into existing steam power plants, thus allowing to increase the design capacity to such an extent that depends on the type of strategy to exploit the waste heat from the additional gas turbine. In this study a new repowering concept is proposed. It involves the integration of an additional unit based on a gas turbine into an existing combined cycle gas turbine (CCGT). Based on this concept, two repowering options are examined. In the first one (Option A), the waste heat from gas turbine flue gases is used to produce steam in a one pressure level steam generator. In the second option (Option B), the exhaust waste heat recovery promotes the generation of a synthesis gas in a methane steam reformer. The integration of the additional unit is operated by the injection of superheated steam (Option A) and the reformed fuel (Option B) into the combustor of the main power plant, thus allowing for a further increase in power output of both topping and bottoming cycles. The simulation study allows to compare the repowering options with respect to the potential increase of power capacity, as well as in terms of energy marginal performance parameters.


Author(s):  
Hongguang Jin ◽  
Xiaosong Zhang ◽  
Hui Hong ◽  
Wei Han

In this paper, a novel gas turbine cycle integrating methanol decomposition and the chemical-looping combustion (CLC) is proposed. The system study on two methanol-fuelled power plants, the new gas turbine cycle with CLC combustion, and a chemically intercooled gas turbine cycle, has been investigated with the aid of the exergy analysis (EUD methodology). In the proposed system, methanol fuel is decomposed into syngas mainly containing H2 and CO by recovering low-temperature thermal energy from an intercooler of the air compressor. After the decomposition of methanol, the resulting product of syngas is divided into two parts: the most part reacting with Fe2O3, is sent into the CLC subsystem, and the other part is introduced into a supplement combustor to enhance the inlet temperatures of turbine to 1100–1500°C. As a result, the new methanol-fuelled gas turbine cycle with CLC had a breakthrough in performance, with at least about 10.7 percentage points higher efficiency compared to the chemically intercooled gas turbine cycle with recovery of CO2 and is environmentally superior due to the recovery of CO2. This new system can achieve 60.6% net thermal efficiency with CO2 separation. The promising results obtained here indicated that this novel gas turbine cycle with methanol-fuelled chemical looping combustion could provide a promising approach of both effective use of alternative fuel and recovering low-grade waste heat, and offer a technical probability for CLC in applying into the advanced gas turbine with high temperatures above 1300°C.


Author(s):  
Hongguang Jin ◽  
Xiaosong Zhang ◽  
Hui Hong ◽  
Wei Han

In this paper, a novel gas turbine cycle integrating methanol decomposition and the chemical-looping combustion (CLC) is proposed. Two types of methanol-fueled power plants, including the new gas turbine cycle with CLC combustion and a chemically intercooled gas turbine cycle, have been investigated with the aid of the T-Q diagram. In the proposed system, methanol fuel is decomposed into syngas mainly containing H2 and CO by recovering low-temperature thermal energy from an intercooler of the air compressor. After the decomposition of methanol, the resulting product of syngas is divided into two parts: the part reacting with Fe2O3 is sent into the CLC subsystem, and the other part is introduced into a supplement combustor to enhance the inlet temperatures of the gas turbine to 1100–1500°C. As a result, the new methanol-fueled gas turbine cycle with CLC had a breakthrough in thermodynamic and environmental performance. The thermal efficiency of the new system can achieve 60.6% with 70% of CO2 recovery at a gas turbine inlet temperature of 1300°C. It would be expected to be at least about 10.7 percentage points higher than that of the chemically intercooled gas turbine cycle with the same recovery of CO2 and is environmentally superior due to the recovery of CO2. The promising results obtained here indicated that this novel gas turbine cycle with methanol-fueled chemical-looping combustion could provide a promising approach of both effective use of alternative fuel and recovering low-temperature waste heat and offer a technical probability of blending a combination of the chemical-looping combustion and the advanced gas turbine for carbon capture and storage.


Author(s):  
S. S. Stecco ◽  
U. Desideri ◽  
B. Facchini ◽  
N. Bettagli

The humid air cycle (Rao, 1990), recently proposed, is an intercooled gas turbine cycle, having an air-water mixing evaporator before the combustion chamber, and a recovering system for exhaust gases. The solution appears to have several advantages: increase in efficiency, increase in power output, reduction of NOx. These important effects are similar to those encountered in STIG (STeam Injection Gas turbine) or CHENG (Saad and Cheng, 1992) power plants, however the particular non-isothermal vaporisation here considered enhances the efficiency increase. Considering a TIT (Turbine Inlet Temperature) at 1273 K and combustion with methane, three different plant solutions are considered, where modifications are related to water circuit, to determine the most important parameters affecting the cycle’s performances. The results show the advantage of employing a dry cooling tower to lower the recirculating water temperature or the total mass flow coming from evaporator. Both cases result in a lower exhaust gases temperature. The advantages and comebacks of the three cycles are taken into consideration and discussed in detail, selecting a possible optimised plant solution. The paper emphasises also the practical feasibility of this plant.


2012 ◽  
Vol 135 (1) ◽  
Author(s):  
Maya Livshits ◽  
Abraham Kribus

Solar heat at moderate temperatures around 200 °C can be utilized for augmentation of conventional steam-injection gas turbine power plants. Solar concentrating collectors for such an application can be simpler and less expensive than collectors used for current solar power plants. We perform a thermodynamic analysis of this hybrid cycle, focusing on improved modeling of the combustor and the water recovery condenser. The cycle's water consumption is derived and compared to other power plant technologies. The analysis shows that the performance of the hybrid cycle under the improved model is similar to the results of the previous simplified analysis. The water consumption of the cycle is negative due to water production by combustion, in contrast to other solar power plants that have positive water consumption. The size of the needed condenser is large, and a very low-cost condenser technology is required to make water recovery in the solar STIG cycle technically and economically feasible.


2015 ◽  
Vol 5 (2) ◽  
pp. 89
Author(s):  
Munzer S. Y. Ebaid ◽  
Qusai Z. Al-hamdan

<p class="1Body">Several modifications have been made to the simple gas turbine cycle in order to increase its thermal efficiency but within the thermal and mechanical stress constrain, the efficiency still ranges between 38 and 42%. The concept of using combined cycle power or CPP plant would be more attractive in hot countries than the combined heat and power or CHP plant. The current work deals with the performance of different configurations of the gas turbine engine operating as a part of the combined cycle power plant. The results showed that the maximum CPP cycle efficiency would be at a point for which the gas turbine cycle would have neither its maximum efficiency nor its maximum specific work output. It has been shown that supplementary heating or gas turbine reheating would decrease the CPP cycle efficiency; hence, it could only be justified at low gas turbine inlet temperatures. Also it has been shown that although gas turbine intercooling would enhance the performance of the gas turbine cycle, it would have only a slight effect on the CPP cycle performance.</p>


Author(s):  
W. V. Hambleton

This paper represents a study of the overall problems encountered in large gas turbine exhaust heat recovery systems. A number of specific installations are described, including systems recovering heat in other than the conventional form of steam generation.


Author(s):  
Akber Pasha

In recent years the combined cycle has become a very attractive power plant arrangement because of its high cycle efficiency, short order-to-on-line time and flexibility in the sizing when compared to conventional steam power plants. However, optimization of the cycle and selection of combined cycle equipment has become more complex because the three major components, Gas Turbine, Heat Recovery Steam Generator and Steam Turbine, are often designed and built by different manufacturers. Heat Recovery Steam Generators are classified into two major categories — 1) Natural Circulation and 2) Forced Circulation. Both circulation designs have certain advantages, disadvantages and limitations. This paper analyzes various factors including; availability, start-up, gas turbine exhaust conditions, reliability, space requirements, etc., which are affected by the type of circulation and which in turn affect the design, price and performance of the Heat Recovery Steam Generator. Modern trends around the world are discussed and conclusions are drawn as to the best type of circulation for a Heat Recovery Steam Generator for combined cycle application.


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