Abstract
As the continuation of the author's former paper in This Journal of March, 1921, few remarks are given on the formation of fume ions in elctrical precipitation. The following is the abstract for the papers, part I and part II.
Assuming the fume particle and the ion are conductive spheres, the author derived the theory of formation of fume ions. When the charges on the particle and on the ion are of equal sign, the energy of the system has a maximum value at a certain distance, within which the ion is attracted to the particle. However when the char-ges are opposite, there acts always an attractive force between them, but this force predomi-nates effectively within a definite distance. These definite distances, the effective distances as called by the author, decrease with the increase of the ratio of the charge on the particle to that on the ion for the former case and increase for the lattcr. The author considers that the ions which jump in within the effective distances to the particle are attracted and give their charges to it. Thus the larger the charge on the particle becomes the more di-fficult for the particle to attract the similarly charged ions, while the easier to attract the oppositely charged ions. Finally when the rate of the recombination of similarly and oppositely charged ions to the particle are equal, the charge on the particle becomes a defi-nite value and can not increase further. The author calculated theoretically their quantitative relation and concluded that the charges on the particle can be approximately represented by 1/2×N'V'/NV times the charge of ion; where N, N' and V, V' are the respective numbers of ions per unit volume and relative velocities of ions to the particle, In order to keep the charge on the particle large this ratio should be increased as far as possible an I unless the ratio of densities of both kinds of ions be greater than 2 (assuming equal relative velocities) the charge on the particle can not be definite. From this standpoint the author discussed the charge and the motion of particles in the space between two parallel plat electrodes and theoretically shon el the reason why the precipitation efficiency of the treater of prallel plate type is inferrior to that of the cylindrical type. He also criticizes the experiments of Dr. Hauer. (Ann. der Phys. Bd . 61, No. 3. 1920) with his own view. The author also treats the effeot of temperature. When the temperature of the gas rises, the kinetic energy of ion increases and if this energy becomes so large as to permit the free motion of ions against the attractive force between the paticle and the ion, the formation of fume ions becomes much lmitde. This temperature is calculated to be very much higher (about 3000°C) than we may attain in our engineering circle. The formation of fume ions where the particles are not conductive is also treated similarly and it is shown that the li niting temperature is in the range of our attains. The certain kinds of dusts treated in the electrical precipitation are not conducive. In this case, however, the moisture and other impurities adhered to the surface of the dust are sufficient enough to give some conductivity. It is natural that such kinds of conductivity is easily affected by a small change of temprature and other gas con-ditions. The author, from these stand views, discusses the re'ation among the pre iptation efficiency, the gas condition and properties of particles, and finally concludes that the high, temperature of gas and the low conductivity of particle hinder the formation of fume i us and lower the precipitation efficiency. The author showed that these conclusions are well coincident with the working data of the precipitation treatr for the gas of 180, 000 cub. ft. per min. at the As io Smelter of Japan.
