DD210979A1 - METHOD AND DEVICE FOR DETERMINING THE STRENGTH OF SOLID SUBSTANCES - Google Patents

Abstract

The invention relates to a method and a device for determining temperature-, pressure- and atmosphere-dependent strength values of solid porosic substances in the temperature range from 20 high degrees C to 1500 high degrees C. The invention can be used in the quality control in the testing. With the invention, the strength is to be determined under practical conditions. According to the invention, the object is achieved by introducing the sample piece to be examined into a chamber filled with a defined gas atmosphere, which is located in an oven. Subsequently, the sample is drilled with a certain adjustable contact pressure and the penetration depth of the drill is recorded as a function of time. The resulting function provides information about the strength and the homogeneous structure of the sample material. The device for implementing the method consists of a furnace with a definable gas atmosphere fillable chamber, a drill and a measuring device for detecting the penetration depth of the drill as a function of time.

Description

Title of the invention

Method and device for determining the strength of solids

Field of application of the invention

The invention relates to a method and a device for determining temperature- and atmospheric-dependent strength values of solid porous substances, in particular solid fuels such as coke and the like. Ä. As well as refractory materials in the temperature range of 20 C to 1500 ⁰ C.

The invention is thus in the testing in quality determination, especially in the industry of solid fuels, the refractory industry and conditionally used in the building materials industry.

Characteristic of the known technical solutions

On solid porous materials, such as. B, solid fuels, in particular on cokes, and on refractory materials are dependent on the application, specific requirements in terms of strength values · The higher z. As the coke, the lower the risk of crushing and attack of undersize or caused by abrasion Koksgruses. So must z. B. good foundry coke classified by piece size and be sufficiently strong.

21st OCT. 1982 * 042 271

At present, the coke strength is usually determined indirectly by determining the troran strength. As a measure of the strength of foundry coke apply the so-called H40, M80 and MlOO VVerte after drumming. These values are those coke fractions remaining after testing on a sieve of 40, 80 and 100 mm hole diameter.

A second way to determine the pressure and abrasion sensitivity of granular materials under mechanical stress is described in DE-AS 27 01 152. Here is a lot of a granular substance dense packing and defined grain fraction is suddenly exposed to a gas pressure wave high kinetic energy. The granular material is subjected to pressure and friction. To evaluate this test, a sieve analysis is then carried out.

In a further description of the invention (DE-AS 23 04 375) a hardness tester is described in which a fixed to a spindle parabolic shaped indenter penetrates under the action of a constant weight in an opposing specimen. In this case, the weight works against a calibrated spring system such that the test force acting on the test specimen decreases linearly with increasing penetration depth.

The penetration depth is measured electronically.

In DE-OS 28 49 203 a device for measuring the abrasion resistance of materials, in particular the material surface, a sample to be examined is shown. In this case, a driven by means of a motor, «circulating, coated with abrasive friction wheel is printed on the surface of the sample, wherein between the friction wheel and the sample, a reciprocal relative movement takes place. Oe greater the abrasion of the examined sample, the lower their strength.

The strength values determined in the aforementioned ways do not characterize the strengths of the tested substances with sufficient accuracy. These test methods and devices only allow the determination of strength values under normal conditions, ie. H. at normal atmospheric pressure in free atmosphere.

It is not easy to conclude from the results obtained on the strength behavior under practical conditions. Furthermore, with these methods and devices, only the surface hardness of the test specimen can be determined. Only drumming makes it possible to obtain information about the homogeneity of the material tested by subsequently optically examining the material to be tested. However, no concrete value can be determined.

In order to determine the optimal possible uses of solid materials, it is necessary to determine their strength values under conditions of use, i. H. to be determined at changed pressure and temperature conditions as well as with changed gas atmosphere.

Experimentally performed hot drums did not bring in practical operation the expected results and are also associated with a very high technical complexity.

Object of the invention

The aim of the invention is to be able to determine the strength and the homogeneity of solid porous substances, in particular solid fuels, in a simple manner under practical conditions.

Explanation of the essence of the invention

The invention has for its object to provide a method and an apparatus for determining the strength characteristic

and the homogeneity of solid porous materials under different, adjustable, practical conditions affecting the substance under test, such as temperature, pressure and gas composition.

According to the invention the object is achieved in that the sample to be examined fixed in a chamber on a pedestal, then exposed in this chamber a certain adjustable temperature and Gasatrnosphäre and is drilled with a certain adjustable contact pressure, that the penetration depth of the drill into the specimen in dependence recorded by the time and the result is evaluated mathematically-statistically.

Di, e inventive device for implementing the method consists of an oven in which a fillable with a defined gasatin chamber chamber is arranged, a drill pipe with a drill material adapted to the material to be tested and a Meßeinrich ^ tion for detecting the penetration depth of the drill as a function of currently.

In a further embodiment of the invention, the device has the following features:

- The fillable with a gas atmosphere chamber is made of a refractory material and has openings for the drill and a temperature sensor;

- In the middle in the bottom and in the lid of the oven is ever provided a hole for the gas supply or »for the drill;

- In the middle of the furnace chamber surrounded by the chamber provided with gas openings pedestal for receiving and fixing the specimen is arranged;

- The measuring device consists of a Halbleiterwegaufnehmer, via a tripod and a 3ustierarm

and by means of a centering element in the middle above the drill pipe can be set up;

- To drive the drill a synchronous motor is arranged laterally;

- On the drill string means for changing the contact pressure of the drill is arranged.

Compared to the known methods, the inventive method has the advantage of being able to determine the strength of solid porous substances under practical conditions. Furthermore, the homogeneity of the material strength can be determined easily.

embodiment

The device according to the invention will be explained in more detail below with reference to several drawings and curves.

Show it:

Fig. 1: Schematic representation of the front view of the device

Fig. 2: Enlarged view of the sample area

Fig. 3: Enlarged view of the registration unit

Fig. 4: strength characteristic of the coke A.

Fig. 5: strength characteristic of coke B

Between the furnace linkage 1 is the furnace body, which consists of the furnace shell 2 and a refractory lining 3. In the immediate vicinity of the cylindrical furnace inner wall heating elements 4 are installed. With the existing SiC heating rods 5 temperatures up to 1500 ⁰ C can be achieved in the furnace interior. For measuring the test temperatures in the immediate vicinity of the sample or heating element, a thermocouple 6 is arranged laterally on the furnace, said thermocouple being arranged via a guide 7

in the chamber 8 can be advanced to the specimen. Oer bottom and the lid 9 of the furnace each have an opening in the middle. In the bottom opening of the gas supply nozzle 10 is embedded. Through the opening in the furnace lid, the drill pipe 11 is guided. In the oven compartment 5, a pedestal 12 for receiving and fixing the specimen 14 is arranged centrally, which is provided with gas openings 13. These openings are arranged go that with central arrangement of the pedestal 12 ici furnace interior 5 a connection with the gas supply nozzle 10 is made. The specimen 14 is fixed in the pedestal 12 by means of a cylinder 29 weighted by a weight-increasing means, in which the specimen is locked by means of several screws.

The pedestal 12 including the specimen 14 is surrounded by a chamber 8, which consists of a heat-resistant material. This chamber 3 is supplied to a defined gas atmosphere and maintained in this.

To carry out the drill string through the chamber 8, this also has an opening on its upper side.

Above the furnace, a heat shield 15 carried by the furnace string 1 is arranged. This has in its center-to carry out the drill string 11 also has an opening.

For receiving the drive and the measuring device, a likewise supported by the furnace rod 1 support member 16 is disposed above the heat shield 15. The drive of the drill pipe 11 consists of a synchronous motor 17 and a chain drive 19. To accommodate the rotational movement of the drill pipe 11, a gear 18 is fixed. This gear 18 is on the drill pipe 11th

vertically movable. By engaging in a groove 27 pin twisting against the drill string is prevented.

The synchronous motor 17 ensures a constant rotational movement of the drill pipe 11 · A locking bush 20 arranged on the drill pipe 11 serves to limit the maximum penetration depth of the drill 21 into the test body 14.

A centering element 22 limits the drill pipe 11 upwards. To record the measured variable, d. H. The depth of penetration of the drill 21 as a function of time, is a Halbleitervvegaufnehmer 23 which is fixed by means of a stand 24 and a Dustierarmes 25 on the support member 16. With the aid of the centering element 22 and the Eustierarmes 25, the sensor 28 of the Halbleiterwegaufnehmers 23 can be set centrally above the drill pipe 11. The drill pipe 11 also serves as Meßgestänge.

Between the heat shield 15 and the support member 16 is a stationary relative to the drilling or Meßgestänge 11 weight bearing plate 26 is arranged. By this, the contact pressure of the drill 21 on the specimen. '14 be changed. '''"':-Λ"" ^r ' ^: ^ /.' ?: ' ^: -' ^: '-'ϊ''^' ^: / ^Λ '"' ^: '' .

The process steps required to determine strength characteristics of solid porous substances under certain temperatures and pressures as well as a freely chosen gas atmosphere are described in more detail below and demonstrated by two examples.

Sample preparation begins with the selection of a representative sample from a given amount of material. This test piece is locked in a cylinder by means of several screws. Thereafter, it is filled with a weight-increasing agent in order to obtain the necessary stability during the measuring process.

währleisten. The thus prepared for the measurement pedestal with specimen is now used centrally in the furnace interior space. If required, the central introduction of the chamber intended for measurements under a defined gas atmosphere also takes place in the interior of the oven via the pedestal with specimen already stationed there.

After the Hessapparatur has been brought into the starting position, the temperature, the gas atmosphere and the contact pressure have been set, the drill string is set with the drill by means of the synchronous motor in rotary motion. The penetration depth of the drill into the specimen as a function of time is detected by the Halbleiterwegaufnehmer. This emits an electric signal proportional to this process and thus allows the graphical recording of the penetration depth of the drill as a function of time.

For the depth of penetration of the drill bit as a function of time results in a curve function of the type

y (x) = a + bx

Prerequisite for a valuation of the measurement results of any sample is the determination of the function y = a., + B., X of a standard under analogous defined experimental conditions and the determination of the increase b _{N of} this line as a normal increase. The regression coefficient b., Indicates how the penetration depth of the drill changes on average per unit of time. The larger the regression coefficient, the faster the drill penetrates into the specimen, ie closto

3Ö softer is the material.

For the correlation coefficient r, the norm r = 1 applies, whereby this location characterizes an ideally homogeneously constructed test specimen in which during the measuring process

no strength changes occur in the specimen.

If an inhomogeneous specimen is present, the correlation coefficient r ^ li d. H. there is no ideal linear relationship between the penetration depth of the drill and time.

Accordingly, a statement about the homogeneity of the structure of the test specimen influencing the strength of the specimen can be made about the determination of the correlation coefficient r associated with the equation.

For operative determination of strength parameters under given experimental conditions, the graphic comparison between the curves and the associated scatter bands of the standard sample and the test specimen can be used.

By means of the solution according to the invention, two different types of foundry coke were tested under the same test conditions. From both types of coke, the strength characteristics shown in Table 1 and determined by conventional methods were known (determined at room temperature and normal atmosphere).

Table 1: Known characteristics of both cokes

Characteristic Coke A Coke B

M4O value 90% 71% Mlo value 6% 11% Density 1.1 g / ^cm3 1.0 g / cm ³

Table 2: Characteristics determined by the solution according to the invention

parameter Coke A Coke B y = a + bx y = 2S, 8-0.077 χ y = 33, 5-0,201 χ 5 regression coefficient b 0.077 0.201 Correlation coefficient r 0.999 0.984 Residual scattering SR 0.39 2.01 0 t value 132.2 23.0

From Table 1 it can be seen that, according to the characteristic values M40 and MIO determined in the drum test, the coke A has better strengths than the coke B. In practical melt operation, better coking results were achieved when coke A was used in the cupola furnace than when coke B was used.

The curve functions of the type y = a + bx shown in Table 2 and in FIGS. 4 and 5 give an identical statement,

The mathematically-statistically calculated regression coefficient b of coke A of 0.077 is clearly lower than the regression coefficient b of coke B with b = 0.201, which also documents the higher strength of coke A compared to coke B.

From the present correlation coefficients r _A = 0.999 and r ₀ = 0.984 it can be determined, in accordance with the results of the optical test, that the coke A has a substantially more homogeneous composition than the coke B,

This result is also reflected in the mathematical statistical residual dispersion of SR _A = 0.39 and SR _Q = 2.01.

Both dependencies are statistically highly significant according to the t-test.

Claims (8)

invention claim 1. A method for determining the strength of solids * characterized in that the sample to be examined fixed in a chamber in a pedestal, then exposed in this chamber a certain adjustable temperature and gas atmosphere and is drilled with a certain adjustable contact pressure, that the penetration depth of the Drill into the specimen as a function of time detected and the result is mathematically-statistically evaluated. 2. Apparatus for implementing the method according to item 1, characterized in that it is arranged from a furnace in which a fillable with a definable gas atmosphere chamber, a drill string with a material to be tested adapted drill and a measuring device for detecting the penetration depth of Drill exists as a function of time. 3. Device according to item 2, characterized in that the chamber which can be filled with a defined gas atmosphere consists of a heat-resistant material, in which openings for the drill and a temperature sensor are present, 4. The device according to item 2, characterized in that a hole for the gas supply or for the drill is provided centrally in the bottom and in the lid of the furnace. 5. The device according to item 2, characterized in that centrally located in the furnace chamber surrounded by the chamber provided with gas openings pedestal for receiving and fixing the specimen is arranged. .6. Device according to item 2, characterized in that the measuring device consists of a dio Halbleiterwegaufnehmer which a tripod and a Oust ie rar m as well as by means of a centering member tnittig via the drill string is furnishable · 7. The device according to item 2, characterized in that for driving the drill laterally a synchronous motor is arranged. 8. The device according to item 2, characterized in that a device for changing the contact pressure of the drill is arranged on the drill pipe. Liienu-XSeften drawings