Biomass-Fired Atmospheric Gas Turbine Plant

Author(s):  
M. Fesharaki ◽  
S. Moser ◽  
H. Halozan ◽  
H. Jericha

Considering the expected climate change biomass is one of the promising energy sources for the future; however, burning and only producing low temperature heat means wasting exergy. To utilize this renewable fuel highly efficient cogeneration plants are required. Existing small and medium sized power generation systems using gas turbines have either complicated flow sheets or problems with charging pressurized combustion chambers, which are not yet solved. This project deals with the investigation and the development of an atmospheric biomass combustion chamber combined with an inverted gas turbine cycle followed by a steam cycle. The system consists of a combustor with a wood grate firing working at atmospheric pressure. A gas turbine expands the hot particle loaded exhaust gas with a temperature of about 800 to 1000°C from atmospheric pressure down to a pressure of about 0.35 bar. The exhaust gas of the turbine is used for operating a single-pressure steam generator, the steam is mainly utilized for power generation in a steam turbine, a part stream is used to control the gas turbine inlet temperature depending on the moisture content of the fuel. The gas outlet temperature of the steam generator is about 186°C (Fig. 1, p6) at a pressure of 0.3 bar, one part is used for preheating the air required for combustion, the other part is cooled down by water injection, whereby ashes and particles are separated. The cleaned gas is compressed to atmospheric pressure again (Moser, 1995). Such a system can achieve an efficiency of up to 40 % in the MW electricity range using components, which are available on the market, and at the same time it demonstrates the possibility of highly efficient biomass utilization.

Author(s):  
M. Fesharaki ◽  
H. Halozan ◽  
H. Jericha ◽  
G. Kulhanek

Considering the expected climate change, biomass is one of the promising energy sources for the future. However, burning and only producing low temperature heat means wasting exergy. To utilise this renewable fuel, highly efficient cogeneration plants are requierd. Existing, small and medium sized power generation systems using gas turbines, have, either complicated flow schemes, or problems with fuel charging of pressurised combustion chambers, which are yet to be solved. Here is a solution is presented requiring no preparation of the biomass fuel. In several publications (Jericha 1991, Fesharaki 1995, Fesharaki 1996) the inverted gas turbine cycle has been presented. This project deals with the investigation and the development of an atmospheric biomass combustion chamber, combined with an inverted gas turbine cycle. The system consists of a combustor with wood grate firing, working at atmospheric pressure. The exhaust gas from the combustor, with a temperature of 1050 °C, is cooled by water or steam injection, to a temperature of 730 °C. The exhaust gas is purified in a cyclone and expanded in a gas turbine to a pressure of 0.3 to 0.4 bar. The exhaust gas of the turbine can be used for operating a single-pressure steam generator, and for district heating. The exhaust gas is purified again by condensing the moisture in the exhaust gas, which stems from the biomass and the steam, or water injection after the combustion chamber. The purified gas is recompressed to atmospheric pressure, which is used for combustion-air preheating. With such a system a high electrical efficiency can be achieved, dependent upon the turbo machines, and the use of an additional bottoming steam cycle. Considering the Austrian situation a feasibility study is being carried out. Special attention has been paid to: Turbine design, Exhaust gas purification, and the cycle control. The feasibility study shows, that this concept is practicable, and that several biomass existing heating systems in Austria could be converted for production of electricity.


Author(s):  
Matti Malkamäki ◽  
Ahti Jaatinen-Värri ◽  
Antti Uusitalo ◽  
Aki Grönman ◽  
Juha Honkatukia ◽  
...  

Decentralized electricity and heat production is a rising trend in small-scale industry. There is a tendency towards more distributed power generation. The decentralized power generation is also pushed forward by the policymakers. Reciprocating engines and gas turbines have an essential role in the global decentralized energy markets and improvements in their electrical efficiency have a substantial impact from the environmental and economic viewpoints. This paper introduces an intercooled and recuperated three stage, three-shaft gas turbine concept in 850 kW electric output range. The gas turbine is optimized for a realistic combination of the turbomachinery efficiencies, the turbine inlet temperature, the compressor specific speeds, the recuperation rate and the pressure ratio. The new gas turbine design is a natural development of the earlier two-spool gas turbine construction and it competes with the efficiencies achieved both with similar size reciprocating engines and large industrial gas turbines used in heat and power generation all over the world and manufactured in large production series. This paper presents a small-scale gas turbine process, which has a simulated electrical efficiency of 48% as well as thermal efficiency of 51% and can compete with reciprocating engines in terms of electrical efficiency at nominal and partial load conditions.


Author(s):  
Takayuki Matsunuma ◽  
Hiro Yoshida ◽  
Norihiko Iki ◽  
Takumi Ebara ◽  
Satoshi Sodeoka ◽  
...  

A series of operation tests of a ceramic micro gas turbine has been successfully carried out. The baseline machine is a small single-shaft turbojet engine (J-850, Sophia Precision Corp.) with a centrifugal compressor, an annular type combustor, and a radial turbine. As a first step, an Inconel 713C alloy turbine rotor of 55 mm in diameter was replaced with a ceramic rotor (SN-235, Kyocera Corporation). A running test was conducted at rotational speeds of up to 140,000 rpm in atmospheric air. At this rotor speed, the compression pressure ratio and the thrust were 3 and 100 N, respectively. The total energy level (enthalpy and kinetic energy) of the exhaust gas jet was 240 kW. If, for example, it is assumed that 10% of the total power of the exhaust jet gas was converted into electricity, the present system would correspond to a generator with 24 kW output power. The measured turbine outlet temperature was 950°C (1,740°F) and the turbine inlet temperature was estimated to be 1,280°C (2,340°F). Although the ceramic rotor showed no evidence of degradation, the Inconel nozzle immediately in front of the turbine rotor partially melted in this rotor condition. As a second step, the Inconel turbine nozzle and casing were replaced with ceramic parts (SN-01, Ohtsuka Ceramics Inc.). The ceramic nozzle and case were supported by metal parts. Through tests with the ceramic nozzle, it became evident that one of the key technologies for the development of ceramic gas turbines is the design of the interface between the ceramic components and the metallic components, because the difference between the coefficients of linear thermal expansion of the ceramic and metal produces large thermal stress at their interface in the high-temperature condition. A buffer material made of alumina fiber was therefore introduced at the interface between the ceramic and metal.


Author(s):  
J. E. Donald Gauthier

This paper describes the results of modelling the performance of several indirectly fired gas turbine (IFGT) power generation system configurations based on four gas turbine class sizes, namely 5 kW, 50 kW, 5 MW and 100 MW. These class sizes were selected to cover a wide range of installations in residential, commercial, industrial and large utility power generation installations. Because the IFGT configurations modelled consist of a gas turbine engine, one or two recuperators and a furnace; for comparison purpose this study also included simulations of simple cycle and recuperated gas turbine engines. Part-load, synchronous-speed simulations were carried out with generic compressor and turbine maps scaled for each engine design point conditions. The turbine inlet temperature (TIT) was varied from the design specification to a practical value for a metallic high-temperature heat exchanger in an IFGT system. As expected, the results showed that the reduced TIT can have dramatic impact on the power output and thermal efficiency when compared to that in conventional gas turbines. However, the simulations also indicated that several configurations can lead to higher performance, even with the reduced TIT. Although the focus of the study is on evaluation of thermodynamic performance, the implications of varying configurations on cost and durability are also discussed.


Author(s):  
G. J. Kelsall ◽  
M. A. Smith ◽  
H. Todd ◽  
M. J. Burrows

Advanced coal based power generation systems such as the British Coal Topping Cycle offer the potential for high efficiency electricity generation with minimum environmental impact. An important component of the Topping Cycle programme is the development of a gas turbine combustion system to burn low calorific value (3.5–4.0 MJ/m3 wet gross) coal derived fuel gas, at a turbine inlet temperature of 1260°C, with minimum pollutant emissions. The paper gives an overview of the British Coal approach to the provision of a gas turbine combustion system for the British Coal Topping Cycle, which includes both experimental and modelling aspects. The first phase of this programme is described, including the design and operation of a low-NOx turbine combustor, operating at an outlet temperature of 1360°C and burning a synthetic low calorific value (LCV) fuel gas, containing 0 to 1000 ppmv of ammonia. Test results up to a pressure of 8 bar are presented and the requirements for further combustor development outlined.


Author(s):  
A. Okuto ◽  
T. Kimura ◽  
I. Takehara ◽  
T. Nakashima ◽  
Y. Ichikawa ◽  
...  

Research and development project of ceramic gas turbines (CGT) was started in 1988 promoted by the Ministry of International Trade and Industry (MITI) in Japan. The target of the CGT project is development of a 300kW-class ceramic gas turbine with a 42 % thermal efficiency and a turbine inlet temperature (TIT) of 1350°C. Three types of CGT engines are developed in this project. One of the CGT engines, which is called CGT302, is a recuperated two-shaft gas turbine for co-generation use. In this paper, we describe the research and development of a combustor for the CGT302. The project requires a combustor to exhaust lower pollutant emissions than the Japanese regulation level. In order to reduce NOx emissions and achieve high combustion efficiency, lean premixed combustion technology is adopted. Combustion rig tests were carried out using this combustor. In these tests we measured the combustor performance such as pollutant emissions, combustion efficiency, combustor inlet/outlet temperature, combustor inlet pressure and pressure loss through combustor. Of course air flow rate and fuel flow rate are controlled and measured, respectively. The targets for the combustor such as NOx emissions and combustion efficiency were accomplished with sufficient margin in these combustion rig tests. In addition, we report the results of the tests which were carried out to examine effects of inlet air pressure on NOx emissions here.


Author(s):  
Norihiko Iki ◽  
Osamu Kurata ◽  
Takayuki Matsunuma ◽  
Takahiro Inoue ◽  
Taku Tsujimura ◽  
...  

A demonstration test with the aim to show the potential of ammonia-fired power plant is planned using a micro gas turbine. 50kW class turbine system firing kerosene is selected as a base model. Over 40kW of power generation was achieved by firing ammonia gas only. Over 40kW of power generation was also achieved by firing mixture of ammonia and methane. However ammonia gas supply increases NOx in the exhaust gas dramatically. NOx concentration in the exhaust gas of gas turbine reached at over 600ppm. In the case of the gas turbine operation firing kerosene-ammonia with 31kW of power generation at 75,000rpm of rotating speed, the LHV (Lower Heating Value) ratio of ammonia to the total supplied fuel was changed from 0% to 100% in detail. NO emission increases rapidly to around 400ppm with ammonia at 7% of LHV ratio of ammonia. Then NO emission increases gradually to 600ppm with ammonia at 27% of LHV ratio of ammonia. NO emission has the peak around 60% of LHV ratio of ammonia. NO emission decreases below 500ppm at 100% of LHV ratio of ammonia. The gas turbine operation firing methane-ammonia with 31kW of power generation at 75,000rpm of rotating speed was also tried. NO emission increases rapidly to around 470ppm with ammonia at 7% of LHV ratio of ammonia. Then NO emission increases gradually to 600ppm with ammonia around 30% of LHV ratio of ammonia. NO emission has the peak at 65% of LHV ratio of ammonia. NO emission decreases below 500ppm at 100% of LHV ratio of ammonia. Since the ammonia flame in the prototype combustor seems to be inhomogeneous, ammonia combustion in the prototype combustor may have high NOx region and low NOx region. Therefore there is a possibility of low-NOx combustion. Flame observation was planned to know combustion state for improvement toward the low NOx combustor. Flame observation from the combustor exit was available by extending the combustor exit with the adaptor of the bent coaxial tubes and the quartz window. Swirling flames of ammonia, methane and methane-ammonia were observed near the center axis of the combustor. Flame observation at 39.1kW of power generation was succeeded. In the case of the flame observation, fuel consumption increased due to increase of the heat loss from the combustor. The emissions of NO and NH3 clearly depend on the combustion inlet temperature at 75,000rpm of rotating speed. The emissions of NO and NH3 in the case of the flame observation setting corresponds to the emission in the case of the normal setting at the condition that the power output is 11.2kW lower.


Author(s):  
Michael Welch ◽  
Nicola Rossetti

Historically gas turbine power plants have become more efficient and reduced the installed cost/MW by developing larger gas turbines and installing them in combined cycle configuration with a steam turbine. These large gas turbines have been designed to maintain high exhaust gas temperatures to maximise the power generation from the steam turbine and achieve the highest overall electrical efficiencies possible. However, in today’s electricity market, with more emphasis on decentralised power generation, especially in emerging nations, and increasing penetration of intermittent renewable power generation, this solution may not be flexible enough to meet operator demands. An alternative solution to using one or two large gas turbines in a large central combined cycle power plant is to design and install multiple smaller decentralised power plant, based on multiple gas turbines with individual outputs below 100MW, to provide the operational flexibility required and enable this smaller power plant to maintain a high efficiency and low emissions profile over a wide load range. This option helps maintain security of power supplies, as well as providing enhanced operational flexibility through the ability to turn turbines on and off as necessary to match the load demand. The smaller gas turbines though tend not to have been optimised for combined cycle operation, and their exhaust gas temperatures may not be sufficiently high, especially under part load conditions, to generate steam at the conditions needed to achieve a high overall electrical efficiency. ORC technology, thanks to the use of specific organic working fluids, permits efficient exploitation of low temperatures exhaust gas streams, as could be the case for smaller gas turbines, especially when working on poor quality fuels. This paper looks at how a decentralised power plant could be designed using Organic Rankine Cycle (ORC) in place of the conventional steam Rankine Cycle to maximise power generation efficiency and flexibility, while still offering a highly competitive installed cost. Combined cycle power generation utilising ORC technology offers a solution that also has environmental benefits in a water-constrained World. The paper also investigates the differences in plant performance for ORC designs utilising direct heating of the ORC working fluid compared to those using an intermediate thermal oil heating loop, and looks at the challenges involved in connecting multiple gas turbines to a single ORC turbo-generator to keep installed costs to a minimum.


2021 ◽  
Vol 24 (3) ◽  
pp. 14-20
Author(s):  
Fajri Vidian ◽  
◽  
Putra Anugrah Peranginangin ◽  
Muhamad Yulianto ◽  
◽  
...  

Leaf waste has the potential to be converted into energy because of its high availability both in the world and Indonesia. Gasification is a conversion technology that can be used to convert leaves into producer gas. This gas can be used for various applications, one of which is using it as fuel for gas turbines, including ultra-micro gas ones, which are among the most popular micro generators of electric power at the time. To minimize the risk of failure in the experiment and cost, simulation is used. To simulate the performance of gas turbines, the thermodynamic analysis tool called Cycle-Tempo is used. In this study, Cycle-Tempo was used for the zero-dimensional thermodynamic simulation of an ultra-micro gas turbine operated using producer gas as fuel. Our research contributions are the simulation of an ultra-micro gas turbine at a lower power output of about 1 kWe and the use of producer gas from leaf waste gasification as fuel in a gas turbine. The aim of the simulation is to determine the influence of air-fuel ratio on compressor power, turbine power, generator power, thermal efficiency, turbine inlet temperature and turbine outlet temperature. The simulation was carried out on condition that the fuel flow rate of 0.005 kg/s is constant, the maximum air flow rate is 0.02705 kg/s, and the air-fuel ratio is in the range of 1.55 to 5.41. The leaf waste gasification was simulated before, by using an equilibrium constant to get the composition of producer gas. The producer gas that was used as fuel had the following molar fractions: about 22.62% of CO, 18.98% of H2, 3.28% of CH4, 10.67% of CO2 and 44.4% of N2. The simulation results show that an increase in air-fuel ratio resulted in turbine power increase from 1.23 kW to 1.94 kW. The generator power, thermal efficiency, turbine inlet temperature and turbine outlet temperature decreased respectively from 0.89 kWe to 0.77 kWe; 3.17% to 2.76%; 782 °C to 379 °C and 705°C to 304 °C. The maximums of the generator power and thermal efficiency of 0.89 kWe and 3.17%, respectively, were obtained at the 1.55 air-fuel ratio. The generator power and thermal efficiency are 0.8 kWe and 2.88%, respectively, with the 4.64 air-fuel ratio or 200% excess air. The result of the simulation matches that of the experiment described in the literature.


Author(s):  
Thomas Bexten ◽  
Sophia Jörg ◽  
Nils Petersen ◽  
Manfred Wirsum ◽  
Pei Liu ◽  
...  

Abstract Climate science shows that the limitation of global warming requires a rapid transition towards net-zero emissions of greenhouse gases (GHG) on a global scale. Expanding renewable power generation is seen as an imperative measure within this transition. To compensate for the inherent volatility of renewable power generation, flexible and dispatchable power generation technologies such as gas turbines are required. If operated with CO2-neutral hydrogen or in combination with carbon capture plants, a GHG-neutral gas turbine operation could be achieved. An effective leverage to enhance carbon capture efficiency and a possible measure to safely burn hydrogen in gas turbines is the partial external recirculation of exhaust gas. By means of a model-based analysis of a gas turbine, the present study initially assesses the thermodynamic impact caused by a fuel switch from natural gas to hydrogen. Although positive trends such as increasing net electrical power output and thermal efficiency can be observed, the overall effect on the gas turbine process is only minor. In a following step, the partial external recirculation of exhaust gas is evaluated and compared both for the combustion of natural gas and hydrogen, regardless of potential combustor design challenges. The influence of altering working fluid properties throughout the whole gas turbine process is thermodynamically evaluated for ambient temperature recirculation and recirculation at an elevated temperature. A reduction in thermal efficiency can be observed as well as non-negligible changes of relevant process variables. These changes are more distinctive at a higher recirculation temperature


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