Coal is a valuable primary energy source that has excellent supply stability and economic efficiency. Japan has extremely low energy self-sufficiency and coal-fired power generation is positioned as an important base load power supply. One urgent issue we face is to find realistic countermeasures that significantly reduce CO2 emissions from coal-fired power plants which produce a large volume of CO2 emissions. Therefore, we have launched the Osaki CoolGen Project since April 2012 as an “Integrated Coal Gasification Fuel Cell Combined Cycle (IGFC) Demonstration Project” subsidized by Ministry of Economy, Trade and Industry (until 2015 FY) and New Energy and Industrial Technology Development Organization (from 2016 FY). This project aims to realize innovative low-carbon coal-fired power generation that combines an IGFC, an extremely efficient coal-fired power generation technology with high-performance CO2 capture technology for the purpose of significantly reducing CO2 emissions from coal-fired power generation. This project consists of three steps. In the first step, demonstration tests of the oxygen-blown Integrated coal Gasification Combined Cycle (IGCC), which is the base technology for IGFC, are implemented. The construction of the first step was started in March 2013 and commissioning of it was started in April 2016. The demonstration testing of the first step started in March 2017. In the second step, we plan to carry out demonstration tests of the oxygen-blown IGCC with CO2 capture equipment. In the third step, demonstration tests of an IGFC system combined the demonstration plant of the second step with fuel cell is planned.
This paper summarizes researches about combustion technologies related to hybrid rockets, focusing on the enhancement of regression rates of solid fuels and the development of techniques for measuring fuel gasification rate. Methods for enhancing the regression rate were divided into two groups: improving the physical or chemical properties of a solid fuel, and improving the combustion flow field in a combustion chamber. In the former group, the use of liquefying fuels like paraffin-wax has become the mainstream of recent hybrid rocket development activities because these fuels have been shown to provide regression rates that are two to three times higher than values encountered with conventional solid fuels. Measuring the history of the fuel gasification rate in a hybrid rocket is not easy, and it has been an important subject in this field. Measurement techniques fall into two categories: the direct measurement of fuel thickness or fuel weight, and reconstruction techniques that estimate fuel flow rate through easily measurable histories such as liquid oxidizer flow rate, chamber pressure, thrust, etc. Recently, a new method to estimate the nozzle throat area history during firing was developed by improving on a reconstruction technique.
Following France, the UK also announced the ban on selling internal combustion engine cars from 2040. Germany and other European countries also show a posture following this, and the wave of global environmental regulations is getting more and more stringent. This wave is not limited to automobiles, and a similar regulation strengthening has been indicated for internal combustion engines for ships on the high seas. With regard to NOx, the regulation to discharge less than about 20% of current condition on some designated emission control area (here after ECA), and the ECA will be further expanded in the future. As for SOx, it was decided last year that the sulfur content in the fuel will be 0.5% or less after 2020. (0.1% or less in ECA). Diesel engines that used heavy fuel oil have been used for internal combustion engines for marine vessels. In response to such environmental regulations, the development of dual fuel engines with liquefied natural gas and heavy oil has been developed in recent years. Here we describe the mechanism and environmental performance of the marine dual fuel engines and the actual fact of conversion work to a DF engine of a diesel engine for onshore power generation.
In this report, co-combustion of MSW(municipal solid waste) and Landfill waste, co-combustion of MSW and sewage sludge come up as examples of combustion of “Hybrid fuel”. MSW itself is also “Hybrid fuel” which consists of plastics, paper and kitchen waste, and so on. Though the composition and the calorific value of fuel (waste) are important factor to design and operate an incineration plant, these important factors are influenced by season, collecting area of waste, event such as “New year holidays”. For this reason, the operator usually cannot control of these important factors before feeding waste to a furnace. Fluidized-bed which is suitable for wide range of characteristics of waste is used for incinerator /gasifier of waste as “Hybrid fuel”, and advanced control systems such as “model based predictive control” and flue gas control logic by machine learning are applied to incineration system.
Modeling of particle generation and growth in gas phase is important in various fields of science and technology. The size and shape of particles are resulted in both chemical reaction and physical phenomenon including nucleation, coagulation, and sintering. In case where the sintering rate is much higher than coagulation rate, the conventional numerical model for spherical particles is available: the characteristic of spherical particle is expressed by one parameter. Otherwise, at least two parameters are needed to express the morphological characteristics of non-spherical particles. One of the most successful ways is to express the characteristics by surface area and volume of particles. They are available to express the sintering rate and to correct the particle motion and coagulation rate properly. In order to express two-dimensional particle size distribution, a sectional expression was developed, and then it was evolved to two-dimensional discrete-sectional expression. In the former part of this article, the motion of particle and coagulation are descripted briefly. In the latter part, modeling of generation and growth of spherical particle and non-spherical particles by one and two dimensional discretesectional method are descripted.
Fractal dimension (Df) is a parameter to determine geometric structure of the objects. Fractal dimension has been applied to characterize the agglomerates generated by Brownian coagulation in the gas-to-particle conversion process such as combustion. In this review, basic principle of fractal dimension is firstly introduced. Then, various methods for analyzing fractal dimension of agglomerates are explained. Image analyzing is a powerful tool to directly estimate fractal dimension of loose agglomerates (Df < 2). Aerosol techniques such as electrical mobility analysis has been also applied to measure the fractal structures of agglomerates in the gas phase.
Briefly reviewing the author's path through the research on in-flame diesel soot formation and oxidation processes, a personal reflection on the past and a vision for the future regarding the general research attitude are shared. In the first phase of the author's research path, strong LIF from in-flame PAHs curiously evolved from an obstacle in the LIF measurements of in-flame radicals into a primary research target of the author over following years. Through the development process of simultaneous imaging of PAHs-LIF and soot-LII in diesel flame, it was learned that persistence on the research target, knowing the world state-of-the-art and ideas to overcome various limitations are important. In the second phase of the path, persistence on the complicated and unexplained PAHs' LIF spectra, an encounter with a lovely 70's paper on the EEM technique from MIT and a successful experience in the Rainbow Laser pulse generation by Raman cell might have misled the author to a “maniac” research direction. A desire gradually emerged for research outputs to be practically useful but still unique to universities. In the third phase of the path, an international research collaboration on direct thermophoretic sampling and TEM analysis of diesel in-flame soot started. The persistence on the research target, collaborations with friends working on the world state-of-the-art, and ideas and students' power to overcome various limitations continued and added to be important. However, a research output with practical usefulness had not been reached yet. In the fourth or current phase of the path, research on diesel late combustion reduction within the framework of “SIP Innovative Combustion Technology” started. It is becoming increasingly important to properly understand the needs of automotive OEMs and to respond to them by making the best out of one's specialties. A potential of soot emission reduction by injection rate shaping technology is to be explored in the near future.
The detailed flow, temperature and concentration fields of a hydrogen-air Bunsen flame have been examined by a precise numerical study that uses the exact transport properties and the full chemical reaction mechanism. The study has revealed that the chemical reactions along the flame cone portion do not remain uniform; the H2 consumption rate decreases towards downstream. The decrease of H2 concentration of the mixture coming into the cone, caused by the radial outward diffusion of mobile H2 molecules, leads to the slowdown of the main H2 consuming elementary reactions downstream. Circumferential curvature of the axisymmetric flame and thermal diffusion are not important in the observed behavior. It is also revealed that the structure of the flame tip is fundamentally two-dimensional, in the sense that the mixture coming into the tip continues the combustion reaction with a strong aid of heat diffusion from the outer flame cone. The result raises a serious question if the tip can be called a part of the self-sustained premixed flame.
In this study the possibility of ultra-lean combustion of methane-air tubular flames was investigated by numerical calculation with detailed chemistry, and the results were compared with counterflow twin flames. As a result, it was found that tubular flames can realize ultra-lean combustion since the radiative heat loss is much smaller than planar 1-D flames because of the smallness of the residence time of the burned gas, but the equivalence ratios of the leanest limits of tubular flames are larger than those of the counterflow twin flames of the similar stretch rates due to an intrinsic tendency of extinction based on the configuration of tubular flames. In addition, the possibility of ultra-dilute combustion of tubular flames of CO2 diluted methane and air was also investigated numerically. The obtained result showed that tubular flames can also realize ultra-dilution combustion, and the extent of dilutions at the largest dilution limits for tubular flames are smaller than those of counterflow twin flames of the similar stretch rate, due to the same reasons as the ultra-lean combustion case.