Second International Conference on Carbon Dioxide Removal (ICCDR-2) was held by RITE and NEDO at Kyoto in October, 1994. More than 400 sci-entists and engineers participated, and 147 papers were reported. ICCDR-2 consisted of 6 sessions; CO2 separation, CO2 sequestration, chemical CO2 utilization, biological CO2 fixation, CO2 reducing technology, and CO2 reducing systems. In session 2 papers on ocean and subterranean CO2 disposal were reported and discussed. Most reports of ocean CO2 disposal dealt with deep sea CO2 sequestration, and most papers of subterra-nean CO2 disposal focused on CO2 sequestration in aquifers. This article also describes the research on deep sea CO2 sequestration at the depths larger than 3700m, which has been carried out by National Institute of Materials and Chemical Research in cooperation with the University of Tokyo and Mitsubishi Heavy Industries.
The effects of alkyl nitrates, alkyl nitrites and organic peroxides on cetane number were investigated to provide the mechanism of the improvement of cetane number improvers. It was found that all the alkyl nitrates, alkyl nitrites and organic peroxides improved cetane number of diesel fuel. In the thermolysis of cetane number improvers, free radicals were formed. Aldehydes, ketones, nitric oxides and nitric diox-ides produced were not concerned with the increment of cetane number. We consider that free radicals have influences on cetane number improvement. The n-alkyl nitrite containing more carbon atoms makes higher improvement on cetane number. The alkyl radicals containing more carbon atoms make higher increment on cetane number.
Four high sulfur and high rank Chinese coals (Nan Tong, Fu Rong, Yanzhou (B) and Zhong Liang Shan) were pyrolyzed rapidly in a nitrogen stream by us-ing a free fall pyrolyzer. Rapid pyrolysis desulfurization, devolatilization and swelling behaviors were different from coal to coal though the four coals have same carbon con-tent. The extent of organic sulfur removal from solid phase ranged from 19% for Zhon Liang Shan to 89% for Fu Rong coals. Nan Tong, Fu Rong and Yanzhou (B) coals were fractionated into three groups by a sink-float method and each group was pyrolyzed rapidly. The highest specific gravity group of Fu Rong coal containing the highest organic sulfur showed the highest removal of organic sulfur. The lowest specific gravity group of the Nan Tong and Yanzhou (B) coals were desulfurized higher than other groups. The extent of organic sulfur removal decreases linearly with the increase of average specific gravity with exception of the highest specific gravity group and non-separated sample of Fu Rong coal.
To elucidate the effect of nitrogen functionality of coals on N2O and NOx emissions, five kinds of model compounds, such as pyridine, pyrrole and aniline, were burnt with kerosene or coal in an experimental fluidized bed having 0.16m inner diameter and 3m height. No remarkable difference in N2O and NOx emission levels was found among the mod- el compounds in spite of the different nitrogen functionality. Furthermore, simulteneous formation of HCN and NH3, which would be of precursors respectively for N2O and NOx formation reactions, in the combustor was recognized in all of the combustion experi- ments. These results suggest the existence of the conversion reactions such as NH3 formation from HCN in the fluidized bed. The ratio of fuel-nitrogen conversion to N2O was lower in model compounds/kerosene combustion in comparison with model compounds/coal combustion, while the conversion ratio to NOx was higher in the former case.
The adhesion and the deposition behavior of coal ash on an entrained-bed gasifier wall were studied with a laboratory scale apparatus equipped with a wall temperature (TW) control device. The ash melting temperature (TM) and the sintering temperature (TS) seemed to influence the adhesive force and deposit form considerably. When TW was below TS, the deposit was a “powder-ash”. Between TM and TS, the deposit was a “sintered-ash”. Near TM, a “solid slag” was formed. The wall temperature also affected the detachment behavior between the wall and deposit. The sticking temperature (TST) was below TS and the deposit could be detached by gravity from the wall when TW was below TST. Experiments indicated wall cooling may significantly reduce both particle-wall and particle-particle adhesive forces. A modest numerical simulation model for ash growth was developed. When grow-ing the deposits formed triple layers, powder-ash / sintered-ash / slag. Easy removal, such as by a soot blower, is possible by not allowing the deposit to become “sintered-ash”.
For the purpose of removing nitrogen atoms from heavy oil by microbial procedures, the first approach was made to obtain microorganisms capable of degrading quinoline as the N-containing model compound by enrichment culture. One iso-late, identified as Pseudomonas putida Q26, was chosen for further study. The degrada-tion of quinoline by this strain yielded initially 2-hydroxyquinoline and then 8-hydroxycoumarin, resulting finally in the complete degradation. This strain was able to degrade quinoline and a few methylquinoline in a complex basic fraction of coal-liquids. It was observed that microbial treatment decreased nitrogen content of the basic fraction of hydrogenated recycle solvent derived from Taiheiyo coal.