In aqueous solution, Nakayama coal reacts easily with chromic anhydride (CrO₃). In comparison with the raw coal, the 1, 100-1, 300cm_-1 IR band of CrO₃ pretreated coal is remarkably diminished. The intensity change arises from the interaction with chromic anhydride and hydroxyl groups in the coal. The magnitude of the decrease correlates well with the amount of reacted chromic anhydride. From a comparison of the IR spectra of products obtained from the reaction of several model compounds with chromic anhydride, the behavior of 1, 100-1, 300cm_-1 IR band was assigned to a change in the C-O stretching vibration in the phenolic hydroxyl groups present in the coal. The method may be applicable as a general method for the determination of phenolic hydroxy groups in coals.

View full abstract

We developed an optimization-type energy model named ROSE (Refuse Option for Supplying Energy) to evaluate the energy-use technologies of the refuse in the city. ROSE is applied to the 23 wards in Tokyo. We evaluate the future potentials of the conventional refuse power generation, the large-scale refuse power generation and the RDF power generation from the views of cost and CO₂ emission reduction.
Without increasing system cost, CO₂ emission can be reduced by refuse energy systems (refuse power generation, RDF power generation). When the large-scale refuse power generation system was assumed to be available, the system cost could be reduced largely. RDF power generation was introduced in case of the CO₂ emission was limited.

View full abstract

Polar fractions in recycle solvent used in a 150t/d NEDOL coal liquefaction pilot plant were divided into acidic, basic, and neutral polar fractions by extraction with NaOH and H₂SO₄ solutions. These fractions were analyzed by GCFID and GCMS to identify the chemical structure.
The acidic fraction was mainly composed of phenols and indanols. Since the basic and neutral-polar fractions contained a large number of hydrogenated and alkylated homologues of polar aromatics, pyrolyzer-GC (Py-GC) system was useful in examining aromatic skeleton of these fractions. Nitrogen compounds in the basic fraction (1.7-5.5wt%) were pyridine type with 2-4 aromatic rings, and those in the neutral-polar fraction (3.3-5.9wt%) were pyrrole type with 2-4 aromatic rings. Most of the phenolic compounds in the neutral-polar fraction were with 3-4 aromatic rings, and the recycle solvent included 11.5-17.4wt% phenolic compounds in total.
The content of the nitrogen compounds in the recycle solvent increased with an increase in nitrogen content of raw coal. The basic pyridine type markedly increased, compared with the neutral pyrrole type. The degree of deactivation of catalyst for solvent hydrotreatment was not influenced by the content of the basic nitrogen compounds.

View full abstract

Coal liquefaction reactors are operated in high-temperature and high-pressure conditions, and the pulverized coal is fed to the reactor after making slurry using recycle solvent with wide boiling point range. Therefore, vapor-liquid distribution of solvent fraction in the reactors is one of the key issues to evaluate kinetic rate and reaction performance because it directly affects the actual residence time of the liquid phase in the reactors.
Using continuous coal liquefaction facility, which has systems for sampling the liquid phase in the reactor, 94 runs were conducted. The liquid samples from the reactors as well as the product liquids were collected and analyzed. The ratio of vaporized solvent fraction to total solvent fraction (Rv (Solv)) was calculated using these data. Rv (Solv) strongly depended on the reaction conditions, and was changed from 25wt% to 95wt%. Mainly, Rv (Solv) was affected by temperature, pressure, gas flow rate through the reactor. It also depended on boiling point distribution and properties of the solvent.
Vapor-liquid equilibrium calculation using SRK method was developed, and its results agreed well with Rv (Solv) obtained by the experiments. These results show that the vapor-liquid equilibrium calculation is useful for analyzing the reaction dynamics and designing coal liquefaction reactors.

View full abstract