It is expected that Integrated Coal Gasification Combined Cycle Power Generation Technology (IGCC) is one of the most important key technologies to get over the vulnerability of energy supply for the future because of its higher thermal efficiency, high environmental acceptability and operability. In comparison with conventional coal firing plant, IGCC includes such peculiar tech-nologies as coal gasification, gas clean up system and gas turbine. In Japan, according to the “Sunshine Project” of which the development program for new energy, we aimed at higher thermal efficiency and have developed pressurized entrained flow gasifier, hot-dry type gas clean up system and gas turbine for low carolific gas. 200 ton per day processing pilot plant was started in gasification operation in June of this year. Also much interest and development are now going on for the IGCC technologies in many countries in the world.
The pressurized fluidized bed combustion is designed to burn a mixture of coal and limestone under pressure in a fluidized condition and to perform in-situ desulfurization at the same time the coal is being burned. This coal burning technology features an improvement of the combustion efficiency by pressure and compactness, in addition to the corresponding property for various kinds of coal possessed by the atmospheric fluidzed bed combustion, and environmental acceptance. Since this combustion is carried out under pressure, combustion gas is sent to the gas turbine and electricity is generated by the surplus energy at the same time the pressure of the combustion air is raised by the compressor. Higher thermal efficiency is expected be-cause a combined cycle power generation system can be composed together with the power generation using a steam turbine. Recently, the problem of global warming is being discussed and its countermeasure has become an urgent issue. Effort should be made to put the PFBC combined cycle power gen-eration system into practical use as quickly as possible as an effective means to reduce CO2 emissions.
Turbine inlet gas temperature and gas turbine capacity for power gen-eration system has been increased recently and 1300°C, 150MW Class gas turbine is now in the stage of practical use. At the present time, the net thermal efficiency of LNG fired combine cycle power generation plant using 1150°C class gas turbine has been reached 43%-44% and 47% is expected for 1300°C class gas turbine. Furthermore, the develop-ments of 1500°C class gas turbine have been started to get over 50% of the net themal effi-ciency in combined cycle power generation plant. From the view point of global environmental problem and energy strategy in Japan, the importance of gas turbine in the power generation system should be increased. This paper describes the present status of high temperature gas turbine technology for power genera-tion.
Steam conditions of 246kgf/cm2g, 538/566°C, super critical pressure single reheating has been dominant as a standard type of the thermal power plants in Japan in recent years. There was no significant progress in steam conditions since the 1960s when the above mentioned conditions were established until June 1989 when the epoch making Kawagoe No.1 unit started commercial operation with the steam conditions of 316kgf/cm2g, 566/566/566°C ultra super critical pressure double reheating. This was because the current materials were used near their limits and enormous funding and time for research and development were needed to improve and develop mate-rials. Also, the investment for improving efficiency could not be compensated by the fuel cost reduction. But the sudden jump of energy price caused by the Oil Shock, steady progress in mate-rial technology, and accumulated experience in designing, manufacturing, and operation of boilers and turbines made a good start in improving steam conditions and led to the comple-tion of the first large scale ultra super critical pressure plants in the world. 316kgf/cm2g, 566/566/566°C class steam conditions will be adopted to new coal fired plants in Japan. There are some elements to be developed to realize 352kgf/cm2g, 649/593/593°C class steam conditions, and it will take a little more time.When we survey future technology, ultra super critical pressure technology contri-butes to the improvement of the efficiency of not only pulverized coal firing and PFBC (Pressurized Fluidized Bed Combustion) plants, but also of the steam cycle in combined cycle plants.
In order to obtain fundamental information on pressurized catalytic gasification of carbonaceous materials, four coal chars loaded with alkaline earth carbon-ates were gasified in a thermobalance at 1, 5 and 25atm of CO2. The measured catalytic activity of the additives was discussed in terms of their chemical states and reactions of them with mineral matters in the coal chars under the gasification conditions checked by X-ray diffraction. All the carbonates except magnesium salt raised the gasification reactivity of the coal chars remarkably, and the catalytic activity at high pressures was almost independent of the coal char species. However, under 1 atm of CO2, the catalytic activities were very small with chars of high ash content. This dependence of the catalytic activity on pressure of CO2 is explained by the results from X-ray diffraction, i.e., alkaline earth carbonates become stable under higher pressure of CO2 but under 1 atm they reacted with silica and alumina components to form silicates and aluminosilicates, and lose the catalytic activity.
The methane combustion test at atmospheric pressure was carried out by using a full scale catalytic combustor with an improved Pd catalyst for 100MW gas tur-bine. The objective is to clarify the feasibility on application of high temperature catalytic combustion to gas turbines for the LNG combined cycle power plant system. The results can be summerized as follows: 1) The manufactured full scale catalytic combustor consists of a reverse annular pre-burner, an annular mixer and Pd catalyst. The dimensions of combustor is 450mm in dia-meter and 800mm in length. 2) Pd catalyst showed high activity in methane catalytic combustion and the combustion reaction proceeded enough at even lower temperatures corresponded to the compressed air temperature in gas turbine systems. 3) The catalytic combustor showed excellent performance in methane combustion at atmospheric pressure. The NOx emission was extremely low and the combustion efficiency was approximately 100% in wide range conditions. As a result, catalytic combustion is ex-pected to be applied to gas turbine combustors.
A recycle solvent fraction of coal liquid derived from Illinois-coal was hydrotreated by NiMo/Al2O3 and CoMo/Al2O3 catalysts using a fixed-bed reactor at high temperature up to 450°C. At low temperature under 390°C, the hydrocracking of a heavy fraction was progressed slightly to the same degree by both catalysts. However, product oils with NiMo were higher in H/C and lower in fa than those obtained with CoMo catalyst. At high temperature of 450°C, the yield of gaseous products and the characteristics of product oils suggested that the removal reaction of alkyl-substituents of coal liquid was progressed and that the activity of NiMo catalyst was higher than that of CoMo catalyst.
The trace organic oxygen analyzer has been developed for the determination of oxygen in highly volatile liquid samples such as coal-derived naphtha. Oxygen in the sample was finally converted to methane by pyrolysis over platinum carbon, followed by methanation reaction, and methane formed was measured by FID. The FID intensity was proportional to the oxygen concentration of 0.05wt% or above for o-cresol/hexane solution and the FID sensitivity was more than 100 times higher than TCD one. The structure of the analyzer is simple and its operation and maintenance are easy.
Discriminant analysis is shown to be applicable for classifying the flammable aqueous solutions of organic compounds. According to the observed flash points, 10vol% aqueous solutions of 30 compounds having diverse structures were divided into two classes. The separation of two classes can be described by the quadratic discriminant func-tion using two easy-to-estimate descriptors, flash points and the aqueous solubilities of pure compounds. The proposed method is useful for making a control chart for the flamma-bility of the aqueous organic compounds.