Pressures, flow rates and tracer arrival times were measured at injection and production wells in the Otake geothermal field. The obtained data were analysed in order to estimate the pressure and transmissibility distribution in the geothermal reservoir.
Substitution of the above mentioned information into the equation of motion of the fluid flow through porous media led to an equation with the transmissibilities and two components of fluid flow as unknown.
The flow and transmissibility patterns in the Otake geothermal field could be estimated by solving numerically this equation, using calculus of finite difference, with suitable boundary conditions.

抄録全体を表示

Effects of rock temperature on the thermal fracturing of imitative hot dry rock specimens by an impinging water jet having a speed of 70 m/s at nozzle exit (1.4 mm I.D.) have been studied with reference to the establishment of drilling and fracturing methods for natural hot dry rocks. These specimens (75 mm in diameter and 150mm in length) were made of castable fire-resistant material. The temperatures of the specimens were room temperature, 200, 400, 600, 800 and 1000°C. The water was at room temperature.
Experimental results indicated that fracturing patterns of specimens varied characteristically with specimen temperature, θ. On the surface of aspecimen struck by the water jet for 10s, a cylindrical hole-shaped cavity with diametem of 3 to 5 mm at the jet stagnation point was observed in both cases of θ=400°C and θ≥800°C. A large crater-shaped cavity was observed at 600°C. The tendency of curves showing the relation between the depth or the volume of cavities and θ was similar to that of the boiling curve, having the maximum value at about 600°C and the minimum at about 800°C. A model for the flow and the heat transfer with boiling of impinging water jets on a high temperature surface was proposed to explain the experimental results.

抄録全体を表示

A production technique in a coal mine consists of two techniques of getting coal in faces and conveying of it to the surface. The coal getting in faces is highly mechanized today, while the conveying is not rationalized sufficiently.
The author examined the conveying systems in a coal mine and suggested the following several rationalization methods: Using of a long belt conveyor instead of several short ones, that means reduction of number of conveyors in a system, increases the efficiency of conveying system; increasing of productivity in the coal face requires the installation of a pocket or bin between the gate road and the further conveying system in roadway. The necessary capacity of bin is determined by a method described in this paper.

抄録全体を表示

The movement of methane gas in the coal seam has been observed by use of tracer gases in several coal mines in HOKKAIDO.
Radioactive methane and freon gas were used as tracer gases. Results gained are as follows.
(1) Almost all quantity of the methane gas in the coal seam moves through cracks, And seams which have no crack are scarcely permeable.
(2) There are three stages of crack generation in coal seams. 1-st stage;(as shown Fig.18-I) The coal seam has not been fractured by the effect of openings and flow rate of gas is expressed by formula (1). But in this stage flow rate of gas is very small. 2-nd stage;(as shown Fig.18-II) Cracks in the coal seam are being increased by the effect of openings and most of gas flow comes through cracks. The flow rate of gas varies widely by places. 3-rd stage;(as shown Fig.18-III) Cracks in the coal seam have been increased in number and grown up in length. Flow rate of gas is calculated basing on fomula (1).
(3) To express the movement of gas in the coal seam, it is not always correct to use diffusion formula (1) only for it.Because in the coal seams where gas drainage has been extensively conducted, it is to think that coal seams are in 2-nd stage usually.
(4) In the coal seam which has few or no cracks, gases hardly move in it. In the case of multi-coal seams extraction, it is very important to drain gas before operation is commenced. Because the seam which must be extracted first has so few cracks that gas drainage from it is usually very difficult. To estimate permeability of gas of the coal seams in-situ which have no cracks and to develop gas drainage technique from them are two problems remained till now.

抄録全体を表示

In this paper, by the finite difference method, the authors considered the two-dimensional-temperature field that consists of cement mortar and a steel rod embedded in the mortar in case that the moving heat source (plasma jet) cuts the field perpendicularly to the steel rod.
The main results obtained are as follows:
(1) Since the thermal diffusivity of steel is much greater than that of cement mortar, the steel rod serves as a heat sinkf or the cement mortar in the high temperature region and as a heat source in the low temperature region.
(2) Whether moving speed of heat source decreases or supplying energy increases, the melted width increases and the steel rod more protrudes from the melted surface of the cement mortar.
(3) The calculated values approximately agree with the experimental values when they are compared to the maximum temperature of the experimental values.

抄録全体を表示

Imperfection, I of jig washer is a coefficient figure showing the separation of Tromp's normal distribution curve of which the parameter of abscissa shall be of log (D-1). Imperfection formula I=Ep/D₅₀-1 express the relation between Ep and D₅₀ in partition curves having same inclination. This matter is mathematically verifiable
When less jigging number is given to particles in bed, imperfection of lower layer is better than upper layer. Difference of imperfection figure I between upper layer and lower layer decreases due to increase of jigging number and finally reach to very close imperfection figures.
However, actually speaking numbers of jigging on commercial jig is not sufficient enough so as the equalize the imperfection figures for every portion of bed layer.
As the observation results of separation test for 33 sets of commercial jigs, the lower imperfection figures are given for the higher separation densities.
It is suggested that even through the jig's imperfection figures theoretically could be reached critical constant, but, in commercial jigs the higher separation densties are given, the lower imperfection figures are indispensably obtainable.

抄録全体を表示

Kinetic study of non-oxidative leaching of synthetic ferrous sulfides in aqueous hydrochloric acid solutions has shown that the leaching rate is directly proportional to both the concentration of acid and the surface area of ferrous sulfides.
Rate constants for the acid leaching reaction exhibits an activation energy of 9.5 kcal/mol regardless of the stoichiometry of sample powders, and this fact suggests that the overall reaction is interface reaction controlled. However, the leaching rate of stoichiometric ferrous sulfide dissolves much faster than non-sto chiometric ore.
Acceleration effect of the dissolution of ferrous sulfides at low PH₂S range of gaseous phase may be attributed to the increase in effective surface area due to the change of adsorption of hydrogen sulfide on the sample surface.

抄録全体を表示