Japan depends on imports for most primary energy resources. To obtain stable supplies of energy and protect the global environment in the future, reexamination of unused resources, reclamation of waste matter, and highly effective use of such resources will be important issues. Discoverable reserves of bituminous raw material and oil shale are believed to contain about 5.8 trillion barrels of oil and are several times larger than the reserves of crude oil. Such oil fields are distributed over Latin America and North America where the political situation is comparatively stable. However, future distribution of energy resources and stable electricity supply in Japan require high efficiency use of those resources as fuel for power generation. Development of integrated gasification combined cycle (IGCC) power generation systems continue worldwide, and such technologies enable high-efficiency generation from various fuel sources. Gasified fuels are chiefly characterized by the gasifying agents and the synthetic gas cleanup methods and can be divided into four types. The calorific value of the gasified fuel varies according to the gasifying agents and ammonia originated from nitroge-nous compounds in the raw materials of bitumen, etc., and depends on the synthetic gas cleanup methods. In particular, air-blown gasified fuels provide low calorific fuel of 4 MJ/m3 and it is necessary to stabilize com-bustion. In contrast, the flame temperature of oxygen-blown gasified fuel is much higher, so control of thermal-NOx emissions is necessary. Moreover, to improve the thermal efficiency of IGCC, hot/dry type synthetic gas cleanup is needed. However, ammonia in the fuel is not removed and is supplied into the gas turbine where fuel-NOx is formed in the combustor. For these reasons, suitable combustion technology for each gasified fuel is important. This paper reviews the trends of technological developments of IGCCs worldwide and outlines the background of combustion technology development of the high temperature gas turbine for IGCC in Japan. Particular combustion technologies developed in Japan are explained in detail.
The effect of acidic compound on the formation of active species in homolytic hydroperoxide decomposition by hindered amine light stabilizers (HALS) was studied. The hydroperoxide decomposition activity of HALS is an important to characteristics of HALS. HALS Ammonium salt, which is a fundamental compound involved in the antagonism between HALS and acidic compounds including phenolic antioxidants, was found to be a key compound for the formation of HALS nitrosonium salt, which was identified as the active species of hydroperoxide decomposition. HALS Nitrosonium salt was not formed from active species for polymer stabilization, such as nitroxide, alkoxide, or hydroxylamine of HALS, but from HALS salt. A formation mechanism of HALS nitrosonium salt is proposed. Furthermore, molecular aggregates formed between HALS and acid compounds are discussed to be important for HALS properties.
The vapor phase Beckmann rearrangement of cyclohexanone oxime (CHO) was carried out over TS-1 with an MFI pore structure and SSZ-31 and SSZ-24 with pore sizes larger than that of MFI to elucidate the effect of the pore size on catalyst deactivation. The deactivation constant over SSZ-24 was the highest among the zeolites used in the study. Furthermore, when the ratio between the molecular size of ε-caprolactam (CL) and the pore size of zeolite was unity, the deactivation constant was maximum over the zeolites at similar acidity. These results indicate that since CL produced on the active sites cannot diffuse from the micropores, the CL reacts to form coke or its precursor over a long residence time. The pore size of the zeolite is the main controlling factor of catalyst deactivation during the Beckmann rearrangement.
The effect of the morphology of the support particles on nickel-catalyzed decomposition of methane into carbon nanotubes and hydrogen was explored using a thermogravimetric apparatus. Er3Ga5O12 synthesized by the glycothermal method was used as the support of the Ni catalyst. As calcination temperature increased, morpho-l-ogy and pore-size distribution of Er3Ga5O12 changed. High carbon nanotube yield was attained over Ni catalyst supported on Er3Ga5O12 particles with spherical shape and smooth surfaces. Various aluminas were also examined for the support of the Ni catalysts. Quite high carbon yield was observed over Ni catalyst supported on spherical Al2O3 particles (Nanophase Technologies Corp.). Spherical support particles with smooth surfaces touch at a point, so can change positions easily. Therefore, the most important factor governing the carbon yield is the morphology of the catalyst support.
Water-related damage is one of the major problems for the durability of the bituminous pavement and concrete slabs of concrete deck bridges. In particular, damage can be drastically accelerated by the intervention of water and some chemicals such as surfactants and salts. Therefore, the mass transfer mechanism of water and the mechanism of chemical absorption in pavement materials are important to study. The authors previously pointed out that water storage in bituminous pavement layers is caused by moisture vapor in the air, and developed a new moisture permeation test apparatus to analyze the mass transfer. Based on this test method, the present study showed experimentally that water and surfactant accumulate in the bridge deck pavement and concrete slabs. Water accumulation in the pavement and deck slabs increases according to the daily climatic fluctuation. The repetitive moisture permeation test showed that alkylphenol-ethoxylate type surfactant applied on the top surface permeates through water-impermeable pavement layers and accumulates in the concrete slab.
Pipeline flaw detection and safety evaluation are very important because of internal corrosion usually caused by the presence of the water (salty or not), and external damage by anchors or other equipment. Any possibility of leakage must be detected before leakage occurs and preventive action should be taken to avoid losses of oil and ecological disasters. The ultrasonic method is the most commonly used to detect material loss and/or cracking of the pipeline. The ultrasonic intelligent pig is used to detect the pipeline thickness, but the complicated offshore and pipeline environment, especially the variable sensor lift-off (distance between ultrasonic probe and pipeline wall under detection), reduces the accuracy of pipeline thickness measurement. The Hilbert-Huang transform was used to extract the signal features, then the Elman neural network applied to eliminate the effect of lift-off variation to improve the flaw detection accuracy. Experiments showed that the accuracy of detected time of flight between the transmitted pulse and echo from the pipeline wall as well as the thickness of the pipeline wall were clearly improved.
Distillation was applied to separate the extracted components and the aqueous methanolic solution from the aqueous extract phase obtained from the solvent extraction of coal tar distillate. Equilibrium extraction of absorption oil, one of the coal tar distillates, was carried out with aqueous methanolic solution and confirmed that nitrogen heterocyclic compounds in absorption oil were selectively extracted into the solvent phase and these components and homocyclic hydrocarbons etc. could be separated by the extraction. The extract phase obtained from this extraction was separated by batch simple distillation. The distillation of the extract phase produced the liquid in the still consisting of two immiscible phases, extracted component-rich and water-rich phases, and methanol-rich distillate. The extracted and solvent components in the extract phase could be separated. The distillation also achieved further separation between nitrogen compounds and homocyclic hydrocarbons etc., which remained in the recovered aqueous methanolic solution phase. The aqueous methanolic solution recovered from this distillation was reused as the solvent for another equilibrium extraction of absorption oil. The separability between nitrogen compounds and homocyclic hydrocarbons etc. was improved by the extraction with the recovered solvent, because the hydrocarbons etc. remaining in the recovered solvent restrained the transfers of these components from the feed absorption oil into the solvent phase. Based on these experimental results, a continuous steady state process separating coal tar distillate using solvent extraction and distillation was designed. Distillation has the potential to separate the extract phase in the extraction process to separate coal tar distillate.
Crude oil and natural gas condensate contain various metals including low levels of mercury. This mercury can cause various problems, such as catalyst degradation, piping corrosion and so on. For example, corrosion of piping in natural gas production plants, blockage of LPG vaporizers, and damage to aluminum components in heat exchangers have been reported. Silicates, alumina, activated carbon, and other materials are all effective adsorbents combined with metal sulfides for removing mercury from natural gas. However, these conventional adsorbents result in a further problem that the metal sulfide dissolves in the petroleum products, such as naphtha. The bonding energy was calculated by computer chemistry to identify new effective materials for mercury removal. Based on the bonding energy calculation, adsorbents with good predicted performance based on alkaline metal sulfide and metal chlorides were prepared using activated carbon with very large surface area as a support. Experiments identified a mercury removing adsorbent which has no effect on the properties of naphtha. Mercury removal equipment with the newly developed adsorbent has been operated in the Shikoku refinery of Taiyo Oil Co. since November 1995. This equipment is operated at normal temperature and pressure, and has processed over 5 million kl during 8 years. This is the one of the longest running mercury removal plants in the world.