Hitachi process

Hitachi Zosen have developed a stirred tank/kettle pyrolysis process for waste plastic (Fignre 15.17) that is characterized by the following features [32, 33]  

Hitachi Zosen have filed two US patents on their plastic-to-oil technology. The relevant US patent numbers are US 5,584,969 and US 5,597,451 [32, 33]. The first patent (5,584,969) Apparatus for thermally decomposing plastics and process for converting plastics into oil by thermal decomposition embodies a two-condenser system with an option for a third. 

In the Hitachi Process the low-boiling component of the gas flowing out from the top of the column of the pyrolysis chamber is cooled and condensed initially in the primary condenser, whereby kerosene is recovered. The low-boihng component of the gas passing through the first condenser without condensation is transferred to the second condenser where it is cooled for condensation, whereby gasoline is recovered. The decomposition gas portion remaining uncondensed from the second condenser is then sent to the gas combustion furnace by way of the water seal device and burned in the furnace [32, 33]. A mass 

Reclaiming Oil from Waste Plastic (Hitachi Zosen Corp.) 

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There has been interest, particularly in Japan, in the production of cross-linked low-density polyethylene foam. Some processes, such as the Furukawa process and the Hitachi process, use chemical cross-linking techniques whilst others, such as the Sekisui process, involve radiation cross-linking. 

The Hitachi process, which has been described in considerable detail by Tamura (1970), uses a somewhat more complex gas-contacting arrangement. A schematic flow diagram of the process as employed in a 55 MW pilot plant is shown in Figure 7-39. The plant processes a portion of the flue gas from a 350 MW boiler. A slipstream of gas is removed from the boiler flue duct after the preheater, cleaned of dust, passed through the adsorption beds, and returned to the boiler stack-gas line. At any time in the cycle, four of the carbon beds are... 

Although the water-wash process is simple, it has the drawback of producing a dilute sulfuric acid product, which is difficult to store, ship, or market. Concentration can be troublesome. There appears to be no further development of the Hitachi process (Behrens et al., 1984). 

Hitachi Wet A flue-gas desulfurization process using activated carbon. 

For clean gaseous effluents, such as those from nitric acid plants, the preferred catalyst is mordenite. For flue-gases containing fly ash, the preferred catalyst is titania-vanadia. The process was developed in Japan in the mid-1970s by a consortium of Hitachi, Babcock-Hitachi, and the Mitsubishi Chemical Company, and by the Sakai Chemical Industry Company. It is widely used in power stations in Japan and Germany. See also SNCR. 

Wright of Advanced Micro Devices discusses the use of Raman microspectroscopy to measure the integrity of a film on semiconductor wafers during manufacture in US patent 6,509,201 and combined the results with other data for feed-forward process control [181]. Yield is improved by providing a tailored repair for each part. Hitachi has filed a Japanese patent application disclosing the use of Raman spectroscopy to determine the strain in silicon semiconductor substrates to aid manufacturing [182]. Raman spectroscopy has a well established place in the semiconductor industry for this and other applications [183]. 

Hitachi Chemical is considering developments of new applications for its crosslinked PE foam. It has been used as roofing material, cushioning and insulation. It is a closed-cell type and does not absorb moisture or water, is chemical resistant and highly shock absorbant. It is easy to handle and may be processed using conventional equipment. Applications are expected to widen to meet future needs. 

Baseline Process. DuPont PI2545, PI2555 and Hitachi PIQ as received from the manufacturer, were spun in a class 100 clean room environment at appropriate spin speeds to achieve 0.5 - 6 y film thickness. The silicon wafer substrates were pre-spun (5K rpm, 30") with 0.05% DuPont VM651 (y-amino propyltriethoxy silane) adhesion promoter in 95/5 (v/v) methanol/HzO. The polyimide film cast on the silane-coated silicon wafer was pre-baked... 

The increasing importance of multilevel interconnection systems and surface passivation in integrated circuit fabrication has stimulated interest in polyimide films for application in silicon device processing both as multilevel insulators and overcoat layers. The ability of polyimide films to planarize stepped device geometries, as well as their thermal and chemical inertness have been previously reported, as have various physical and electrical parameters related to circuit stability and reliability in use (1, 3). This paper focuses on three aspects of the electrical conductivity of polyimide (PI) films prepared from Hitachi and DuPont resins, indicating implications of each conductivity component for device reliability. The three forms of polyimide conductivity considered here are bulk electronic ionic, associated with intentional sodium contamination and surface or interface conductance. 

It appears that both the Hitachi and DuPont polyimide films, when cured, significantly impede the drift of sodium ions at normal device operating temperatures. There is, however, evidence that underlying device oxides can be contaminated by sodium and/or moisture or other polar molecules during the application and curing of the polyimide films. Qeaner resins and adequate device stabilization may control this problem. Further work will be required to characterize contamination levels associated with specific aspects of the processing, such as the adhesion promoter and the polyimide resins themselves. 

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