The recent growing interest in the global environment protection and resourceconservation has necessitated the development of recycling technology in various fields.In the field of polymer materials for automobile as well, especially, technological development forlarge plastic parts is required.Most of large plastic parts are painted by thermoset resin orlaminated with mutually incompatible polymers.So, the recycled materials obtained bysimply melting and kneading have poor mechanical properties because the matrix resins of therecycled materials contain paint fragments or incompatible polymers to the resin.So, it isnecessary to develop the recycling technology eliminating the default by the paint fragmentsand the incompatible polymers.Recently, several recycling technologies were developedwith twin screw reactive extruder.In those technologies, paint fragments are decomposed byreactive agent and polymers are mutually compatibilized by reactive compatibilizer undershear force given by the extruder.In this paper, recent studies were introduced on recyclingtechnologies with reactive extruder for large plastic parts of automobiles, such as paintedbumpers and inner compounds containing foam material.

View full abstract

For the purpose of utilization of waste plastics, waste plastics recycling system was installed in NKK Keihin No.1 Blast Furnace at Oct.1996.To investigate the optimum particle size of plastics injected into a blast furnace, the combustion and gasification behavior of waste plastics has been studied with the drop tube furnace, raceway hot model and the commercial blast furnace.From the observation of a single plastic combustion by the drop tube furnace experiments under around 1200°C, the burning rate of coarse plastic was slower than that of pulverized coal.On the contrary, from the results of plastics injection test with the raceway hot model and commercial blast furnace, it was estimated that combustibility of coarse plastics was much different from that of pulverized coal.The combustion point of coarse plastics located to deep domain in raceway compared with those of fine plastics and pulverized coal.The coarse plastics gave high combustion and gasification efficiency compared with fine plastics and pulverized coal.Moreover, the decomposition products of plastics in the blast furnace top gas and dust were the same as that of pulverized coal operation, although hydrocarbons due to the decomposition of plastics was detected in in-furnace.Thus, it was concluded that waste plastics was completely consumed in the blast furnace, and furthermore, coarse plastics particle was effectively utilized as a reducing agent.On the basis of above results, it is considered that waste plastics injection into the blast furnace is a favorable way to realize material recycling of waste plastics and to solve environmentalissue.

View full abstract

Biogasification occurs in the process of anaerobic fermentation for organic materials.The gas from the anaerobic fermentation process consists of 60%methane gas and 40% carbon dioxide and we call it Biogas.We can use it as the fuel for gas diesel generator obtaining the electricity and heat simultaneously or for CNG automobile.The biogas comes from solar energy and carbon dioxide, so we can also call it “Renewable Energy”. The Anaerobic fermentation is not new technique, but is rather regular technique such for the sewage sludge treatment.The anaerobic fermentation that I am going to describe here is for the organic solid wastes such as kitchen waste, yard waste or food waste and the technique for them has been newly developed in Europe this latest decade.In Japan, we treat the solid wastes by incineration as usual. But the imperfect incineration often yields contaminants that contain unknown material such as dioxins.The organic waste contains a lot of water and it makes the incineration unstable and the risk of emission of contamination increases.More over, the packaging material recycling act that is going to run from 2000 will reduce papers and plastics from the domestic wastes, so the ratio of organic wastes in the domestic wastes will increase relatively then.Biogasification process will become necessary technique to reduce the organic waste from the domestic wastes then and it can yield safe energy and compost.Biogasification technique will become one of most important techniques for environmental safeguards and recycling.

View full abstract

In Japan, mainstream municipal waste processing is by incineration, and this has been established from the viewpoint that it offers stable, sanitary processing for large quantities and that it enables a great reduction in the ultimate disposal volume.However, the annual volume of municipal waste has a tendency to increase year by year.With the decreasing capacity of ultimate disposal sites, further reduction for volume of incineration ash both in municipal solid waste (MSW) and sewage sludge is required.In addition, secondary pollution by the harmful components of heavy metals or dioxins eluded from landslide ash is feared, and the inactive and stabilization of incineration ash has become an increasingly important issue.The melting and solidification process, in which ash is heated up to a temperature higher than the fusion point and melted, then cooled to solidify and recovered as slag, is considered an effective technique that will meet the expectations mentioned above.And, several processes that differ from heat source for ash melting for each other have been appeared in these days, and are divided into two groups equipped with combustion devices or electrical heated up devices.Reported in this paper are the characteristics of typical incineration ash first.And next, ash melting performance, such as behavior of heavy metals contained in ash, the characteristics of the melt and solidification slag for sample ashes taken from different types of incineration are described.These report are based on operation of our established two types of melting furnace, “swirling flow melting furnace” and “plasma melting furnace”. The first one is included in combustion melting methods, and other is in electrical melting methods.Both processes enable the melting furnace to melt a fly ash individually that contains harmful components.As a swirling flow melting furnace, we have operated commercial plants, with the maximum capacity of 120ton/day.On the other, we have operated commercial plant of plasma melting furnace with the capacity of 5ton/day.This commercial plant has the advantage to enables the plasma furnace to melt fly ash of the fluidized-bed incinerator individually.Based on the performance of these plants, we are now going to optimize the design for more large size melting furnace with stable operation.

View full abstract

Characteristics of the volume fraction and the phase velocity of gas-liquid-solid three-phase slug flow with quite large particles in a vertical pipe have been studied experimentally.Air, tap water and aluminum-ceramic balls of mean diameter 24.8mm were flowed in a vertical pipe with 30.8mm inside diameter and about 7.5m in height.The volume fraction of each phase is measured by use of the quick closing valve method and the image processing method based on VTR images, jointly.The same following results that have been obtained in the case of gas-liquid-solid three-phase bubble flow and slug flow with small particles are recognized even in this gas-liquid-solid three-phase slug flow with quite large particles.Each volume fraction of three phases increases with increasing the volumetric flux of each corresponding phase like in the case of two-phase flow.When only the volumetric flux of gas phase or liquid phase increases, the volume fractions of the other two phases decrease.However, if only the volumetric flux of solid phase increases, the volume fraction of gas phase or liquid phase increases in some flow conditions.The equation to estimate the gas phase velocity can be expressed by a linear function of total volumetric flux with small deviation, but the influence of volumetric flux of each phase must be incorporated to express the equations to estimate the velocities of liquid phase and of solid phase because the experimental data distribute with large deviations from linear functions of total volumetric flux.

View full abstract

Gas-liquid-solid three-phase flow in a vertical pipe is observed.Air, tap water and aluminum-ceramic balls of mean diameters 4.16-24.8mm were flowed in two vertical pipes with similar size of 30.3 and 30.8mm inside diameters and about 7.5m in height. Their flows were recorded by a 8mm CCD video camera.At first, in this paper, we introduce the observation of liquid-solid and gas-liquid two-phase flow which are considered as basic multiphase flows of gas-liquid-solid three-phase flow.Flow characteristics of dispersed flows such as existence of the light and shade of dispersed phase and their random movements were described fromthree dimensional view points.

View full abstract

Abrasive jet machinig which is typically blasting is rough working as deburring and rough finishing.But otherwise it has been increasing that the materials used for sernicondector, electronic devices and LCD parts are worked by micro abrasive jet machining, because it is a method of dry manufacturing and high productibity.According to their requests we have developed the micro abrasive jet machining equipment which is a blasting equipment used micro abrasives and is able to work hard and brittle materials for uses of semiconductor, electronic devices and LCD parts in high accuracy The micro abrasive jet machining equipment has an abrasive feeder which is able to supply micro abrasives constantly.We introduce an outline of this equipment and some examples of working in this report.

View full abstract