A computer simulation code was developed to estimate the temperatures in and around a geothermal well.
This code is employing explicit solution method to solve finite difference equations on transient heat transfer problems, and is applicable for three types of fluid flow in the wellbore; injection, production and circulation.
A water circulation test was performed in HY-2 Well located in Yakedake area, Gifu Prefecture, to get field data for the evaluation of the computer simulation code.
Comparisons of computed results were made with the exact solution and field data obtained. These results showed that this simulation code can simulate the temperature in and around the borehole satisfactorily.

抄録全体を表示

Uniaxial compressive tests for eight rocks including one marble, one granite, two andesites and four tuffswere carried out by a servo-controlled testing machineunder a condition of a constant rate of (ε-σ/E'). Completestress-strain curves of all rocks were obtained and it was found that the post-failure behaviour of rocks except a marble can be classifiedto Class II. In all tests, rock failure was fully controlled with the newly proposed negative feed back of stress rate. Itshows agreat potential of the pro-posed testing method to investigate the post-failure behaviour of brittle materials as rocks with aminimum modification to a conventional servo-controlled testing machine.
Finally, a brief discussion concerning the fundamental mechanism of Class II post-failure behaviour isgiven on the basis of the test results.

抄録全体を表示

Searching for the heat generation curve of coals by oxygen adsorption within therange from 30°C to 45°C, we investigated the susceptibility of coals to spontaneous heating.
Numerical calculations were developed with a sphere coalmodel for approximating the temperature rise inaccordance with results obtained by experiment.
Consequently, we came to following conclusions.
1) Assumingthat the initial temperature of model is 45°C and its surface is keeping on the same, thetemperature at the centre of model attained 47.7°C in 30minutesand it required 100 hours in order to drop 1°C.
2) The relationship between temperature andrate of heat generation can be expressed by means of the Arrhenius equation.
lnA=lnA₀-E/RT
The logarithm of the rate (lnA) is proportional to the reciprocal of the absolute temperature (1/T) witha slope of -E/R and an intercept of lnA₀, where E is the activation energy and Ris the gas constant.In this equation, A₀is the amount of heat generation in the initial oxidation process. Using the values of A₀, we can evaluate the susceptibility of coals to spontaneous heating.
3) According to our calculations, elapsing about 16.7 hours from be ginning of oxygen adsorption, the temperature of the model centre comes up to 100°C. After that, the rising curve of temperature has a more steep slope. Fromthese results, we can say that the heat of adsorption in the low temperature oxidation process leads to spontaneous combustion.

抄録全体を表示

A series of rock cutting tests is conducted by drag bits of various geometries. In order to evaluate the effect of rake angle of bit as well as mechanical properties of sample rock on the cutting force, theequation of cutting force Pgiven in previous paper P=(a. t/B+b).t. B+cis applied to the test result, where t is the depth of cut, B is the blade width of bit, a, b and c areparameters as functions of th e rake angle ofbit and mechanical properties of rock. It is concluded that
(a) Parametersa and b decrease with increase of the rake angle of bit.
(b) When parameters a and b are assumed as proportional to the shear strength of rock. both of them depend upon the angle of internal friction of rock as well as the apparent angle of friction between bit and rock. The latter angle is noti ndependent of the rake angle of bit.
(c) Parameter c is approximately proportional to the shear strength of rock, and independent of the rake angle of bit.Furthermore, on the basis of the test result, it is indicated that
(d) The ratio of thrust to cutting force decreases with increase of the rake angle of bit.
(e) When the cross-section of cut groove A is expressed asA=(d.t1B+1). t. B, the parameter d is independent of the rake angle of bit.

抄録全体を表示

The size reduction of waste polymer and composite materials has become an important subject in the field ofwaste reclamation. And then energy consumptions by size reduction of waste polymer and composites as GFRP (Glass Fibre Reinforced Plastics) are very large for the reason of their high strength and plastical properties.
Therefore, using a shredder-type crusher equipped with torque transducer (Fig. 3), the energy consumption by size reduction are measured for polymer and GFRP. And the effects of clearance between cutting and fixed blades and open size of screen on the pulverizing energy have been investigated. The results obtained are as follows:
(1) Pulverizing energy Ue decreased with decreasing clearanceCand increasing open size of screen. Pulverizing energy Ue is shown by next eq. for both polymer and GFRP.
1n (Ue) =A₁·ln (C) +A₂
A₁, A₂: Constants dependent on opensize of screen and material.
(2) Constants for resins andGFRPs are derived from the theory and experimental values. It is recognized thatA₁ for resins is 1.1 and A₁ for GFRP is 1.2

抄録全体を表示

As a further study on the phase equilibria in the metal sulfate-water-ethanol systems, the influence of sulfuric acid adding to the systems was investigated at 298K, and also at 278K for nickel and zinc sulfate systems.
The solubility ofsulfates in sulfuric acid-ethanol-water mixture decreased considerably with increasing concentration of alcohol, and increased slightly with increasing concentration of sulfuric acid. The recoveries of crystallized salts by addition of 2kg of ethanol ranged from a minimum of 64% in the zinc sulfate system to a maximum of 98% in the copper sulfate system for the solutions containing 1 mole of sulfate and 3 moles of sulfuric acid per kilogram of water at 298K.
The temperatures at which heptahydrates transform to hexahydrates in the nickel, cobalt, and zinc sulfate systems varied with amounts of ethanol and sulfuric acid present. Hexahydrates crystallized out from the solutions at lower temperatures in the presence of sulfuric acid.
It may be concluded that these properties can be applicable to practical processes in which sulfuric acid is present in almost all case. In practice, however, it may be more efficient to neutralize the solution prior to crystallization process, or to recycle the spent solution after a partial precipitation of salt from pregnant solution.

抄録全体を表示

The mixed gas containing SO₂ was blown into the H₂O₂ aqueous solution with a vertical down-blow nozzle. The absorption percentage of SO₂ has been measured as a function of the nozzle diameter (1.25-5.9mm), the submerged depth of nozzle (L;-5-20cm) and the gas flow rate (30-80dm³/min). The jet trajectory length S (cm) were measured simultaneously, and the relationship among S, Reynolds number N_Re and the absorption percentage of SO₂ were considered.
When the gas was blown from a nozzle of small diameter, high absorption percentage of SO₂ should be obtained even if the gas flow rate was low and the submerged depth of nozzle was shallow. SO₂in the mixed gas would be absorbed perfectly by the solution when N_Re and L satisfy the next equation.
N_Re>245 (16-L)² (-2≤L≤8)
It was found that S was given by
S=6.8×10^-3N_Re^0.76+L(0≤L)
It seems advantageous to let the nozzle be submerged deep to gethigher fraction reacted in the injection with a vertical down-blow nozzle.

抄録全体を表示

The arsenious ions are removed from aqueous solutions with calcium hydroxide according to the following reaction:
2Ca²⁺+2AsO₂^-+2OH^-=Ca (AsO₂) ₂ Ca (OH) ₂
The arsenic ions are removed according to the following reaction:
4Ca²⁺+2AsO^3-₄+2OH^-=Ca₃(AsO₄)₂ Ca (OH)₂
Consequently, the concentration of As (III) and As (V) in aqueous solutions will be controlled by the solubility product of Ca (AsO₂)₂·Ca (OH) ₂or Ca₃ (AsO₄)₂·Ca (OH) ₂, namely, by pH and the concentration of calcium ion. It was found that, when the initial concentration of arsenic is less than 10 mg/l, As (III) and As (V) were remarkably removed from aqueous solutions by adding a large excess of calcium hydroxide. The concentration of arsenic, therefore, can be reduced nearly completely by using two steps of neutralization with calcium hydroxide. In the first neutralization arsenic is removed less than 10 mg/l, and then a large excess of calcium hydroxide is added to reduce the concentration of arsenic less than the government regulation (0.5mg/l) in the second neutralization. The residue from the second neutralization can be recycled as neutralizing agent to the first one.

抄録全体を表示