Development of the dust collector and the classifier for suspended particulate matter

 
Gas-cyclones are widely used in various industries as particle separators or size classifiers for gas–solid flows because of their simple structure, low cost of manufacturing and maintenance, and high reliability. There is a strong demand in various industries for highly-functional fine powders, particularly with diameters of 0.1 to 1.0 μm, which have particle size distributions with a narrow standard deviation. Hence, there is a strong need for reducing the cut size of cyclone separators and improving their separation accuracy.
  In our laboratory, a novel cyclone that comprises a cone made of porous sintered metal is fabricated. As a new method to control the cut size and to reduce particle deposition on the cone, which affects the cyclone performance, injection of clean air through the porous sintered metal cone is proposed.
Synthesis of the functional powder material by the super rapid Solid-phase Reaction with Microwave Heating

  Solid-phase reactions are widely used to synthesize various functional inorganic compound powders from mixtures of several types of raw material powders. However, this method requires both a long treatment time and an enormous amount of energy to maintain the high temperature. Microwave energy is an important heat source that enables rapid, direct, and selective heating of an object. Since microwave heating improves the yields of products, and considerably increases the reaction rate as compared to conventional heating with an external heat source.
  however, decreased conversion to the product caused by uneven heating due to the nonuniform distribution of the electric and magnetic fields in microwave cavities inhibit the homogeneous progress of the solid-phase reaction.
  In our laboratory
, in order to overcome the disadvantages of the microwave heating method that lead to the inhomogeneous progress of the solid-phase reaction, a novel method for the synthesis of the functional powder material using an air-fed microwave-heated solid-phase reaction is proposed
.
Elucidation of synthesis mechanism of Metallic Oxide Powder by Microwave Denitration Method

The microwave generates heat by its interaction with the dipole and the charge of an object. Hence, a microwave can heat up the object rapidly, directly, and selectively. Furthermore, microwave heating induces a heat spot and superheat.

  In Japan, the microwave heating method has been also applied to a nuclear fuel recycling process. In this recycling process, the aqueous solutions of uranium nitrate and plutonium nitrate extracted from spent nuclear fuel is recycled to the mixture of uranium oxide and plutonium oxide. Therefore, it is very important to investigate the mechanism of the synthesis of metallic oxide powder from aqueous solutions of metallic nitrate, by the microwave heating method. The effects of the oxidation temperature and the microwave absorption abilities of the intermediate and the final product on the microwave denitration are also revealed. Furthermore, the relationship between the progress of the microwave denitration and the temperature distribution in the reactor is also discussed using the numerical simulation.

Synthesis of zeolite from coal Fly Ash and biomass incineration ash and its application to the adsorbent for radioactive materia

In Japan, over 8 millions tons of fly ash are generated per year by thermal power plants and so on as industrial wastes. The amount of discharged fly ash is expected to increase monotonously from now on. A new way to reuse fly ash by synthesizing phillipsite, which can be used as adsorbents, catalysts and so on, with hydrothermal treatment method has been proposed. We have reported effects of the morphology of fly ash and the synthesis conditions on the growth rate and the crystal structure of generated zeolite.   

Furthermore, we also propose the method to synthesize phillipsite selectively and improve the purity and yields of synthesized product powder. We investigate effects of microwave irradiation on the crystalline phase of zeolites synthesized from fly ash and clarify what process is intensively affected by the microwave irradiation. Based on these investigation, the enhancementmechanism of the crystal growth by microwave irradiation will be proposed.

 

Synthesis of Calcium Phosphate Hydrogel from Waste Incineration Fly Ash and Bone Powder and its application to the fuel cell

  Waste incineration fly ash is generated by garbage incineration plants. Over 7 million tons of waste incineration fly ash is discharged per year in Japan. The amount of waste increases annually. The main component of waste incineration ash is Ca. Over 4 million tons of chicken bone is also discharged per year from chicken meat processing plants as industrial wastes in Japan.

  Fuel cells are one of the most important technologies for supplying clean energy. Many types of methods have been investigated in order to reduce the cost of fuel cells and to improve the efficiency of the cell performance. Calcium phosphate hydrogel is thought to be one of the promising candidates for the electrolyte of fuel cells.

  Therefore, the synthesis of calcium phosphate hydrogel from incineration ash and chicken bone powder is proposed as a new effective method for reusing them. The performance of calcium phosphate hydrogel synthesized from CaCO3 reagent and from incineration ash and bone powder is compared.

 

Simulation and Optimization of Dynamic Characteristics of Closed-circuit Pulverization System

  Numerical simulation and experimental studies are conducted on the dynamic characteristics of powder flow rate and particle size distribution in a closed-circuit pulverization system. The performances of pulverizer and classifier are modeled by use of experimental data. The returning powder flow rate is taken into consideration, and material balance equations of each size range are numerically solved by an iterative method.

  It is confirmed by simulation that product and returning powder flow rate, and product mass median particle diameter increase with time and they finally reach constant values.

  The process stabilization time depends mainly on the converged value of returning powder flow rate under different operating conditions of pulverizer and classifier. Experimental data about dynamic characteristics agree with the simulational results, and the reliability of the present simulational method is confirmed.


Investigation about Optimized Dimensions of the Detective Tray for a Sedimentation Balance Type Particle Size Analyzer

  Particle size distribution is measured by various methods, for example, laser diffraction-scattering, electrical sensing zone method, sieving, and so on.

  The sedimentation method can measure the Stokes diameter of particles, which is physically defined clearly. This method has been widely used, and Japanese Industrial Standard adopts this method. Moreover it is very simple and economical to manufacture the particle size analyzer with this method. Effects of the behavior of particles and dispersion medium on the particle size measurement with the sedimentation balance method is investigated by using the visualization technique and the numerical simulation. The dimensions of a detective tray and the sedimentation bath are optimized to improve the measurement accuracy of the sedimentation balance.