DE1196315B - Process for the production of a solid mass for acetylene gas containers - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. α .:

ClOh

German class: 26 b - 44/20

Number:
File number:
Registration date:
Display day:

1196 315
S72121IVc / 26b
January 19, 1961
8. Wed 1965

Acetylene gas containers are used because of their high tendency to deflagration Made from steel because of acetylene gas and its tendency to decompose under pressure and filled with a porous mass, in the capillaries of which acetone is contained. Acetone has a very high level Solvent power for acetylene gas. Instead of acetone, other solvents can also be provided, which are included in the term "acetone" in the following explanations. The used Porous masses are partly loose masses in which the particles are not bound together to a solid body are, partly also solid masses, in which the particles represent a solid body.

For a large intake of acetylene gas, the ratio between the Acetone-absorbing cavities and the particles of loose or solid matter with respect to the Very high in volume. The higher the proportion of the total volume is for the absorption of acetone, the more acetylene can be stored in a container of a given weight and / or volume will. In order to increase the volume ratio, there are several possibilities, of which but some are not feasible in practice, as they led to too large voids in the There were masses that formed little or no capillaries. If the cavities are too large, the Disadvantage that accumulations of free acetylene gas can form and that under the influence of the high under the pressure prevailing in the container, these acetylene gas accumulations are converted into hydrogen and carbon can decompose. In the process of decomposition, a substantial part of the whole is produced without burning Energy content of the acetylene gas free, with the result that strong heating occurs. This leads to a Increase in pressure through which further quantities of acetylene gas are decomposed, causing a chain reaction in Gear is set until the container is finally destroyed.

It is therefore believed that solid masses are preferable to loose masses. The basis for such Solid masses are almost invariably formed by a lattice of calcium silicate, which is about with the chemical Character of concrete can be compared, although made in a different way. That is but there is no obstacle to the fact that some solid masses contain cement in the manufacture of the mass.

The most common is probably the production of porous solid masses, with the lime or an excess of lime-containing substances with silica or containing an excess of silica Finely ground substance for reaction ge-process for the production of a solid mass for Acetylene gas container

Applicant:

AGA Aktiebolag, Lidingö (Sweden)

Representative:

Dipl.-Ing. W. Mouths, patent attorney,

Frankfurt / M., Krögerstr. 5

Named as inventor:

Sten Gunnar Dalen, Lidingö (Sweden)

Claimed priority:

Sweden of January 21, 1960 (564)

brought and mixed with large amounts of water. The raw mass is after the start of setting for example, heated in an oven or in an autoclave, so that the water is superheated and during the subsequent cooling of the acetylene gas container evaporates to form a finely divided capillary-like structure. It has so far not been possible to produce acetylene gas containers that are reliable in this way because there was a certain tendency to explode.

Based on research it can be assumed that the bond between calcium and Silicic acid to form the desired calcium silicate takes place in different reaction phases, until there is monocalcium hydrosilicate in the final state. Up to this state, various, Intermediate phases that have not yet been clarified in some cases. These have different crystalline ones among them Properties. But since the amount of mass enclosed in a steel container is different cannot expand outside the inner volume of the steel container, it follows that the During various phases, mass, sometimes under expansion, acquires a volume equal to that of the Volume in the steel tank corresponds, sometimes under contraction a volume that the Volume of the container falls below. During the course of the reaction, the mass, and when they finally entered their stable phase

509 599/93

it will have the shape of a body which, in terms of the amount of calcium released in statu nascendi, corresponds essentially to that formed by steel containers to be combined with the formation of hydrogen (H ₂ ) and space, but is smaller than this space. Calcium aluminate (Ca ₃ (O ₃ Al) ₂ ).
So there is a gap between the container and the mass enclosed in it. The hydrogen formed during this reaction. During the reaction, under the given circumstances, the mass 5 lies as a body in the container and does not fill its interior in closed bubbles with an internal pressure. The aim in producing the included, which was the solid mass in the container during curing, exceeds a favorable prevailing vapor pressure. It will achieve volume ratio. It should be the solid so that an expansion element mass introduced into the mass body a relatively small proportion in the io, which occupy the total volume during the plastic state, while the larger of the mass body presses it against the inner wall of the part of the volume made of liquid, namely acetone container. Tests have shown that the acetylene gas dissolved therein should exist. actual shrinkage of the body of the mass - such containers are involuntarily exposed to mechanical influences during the time of the plastic state instead of mechanical influences, in which the 15 takes place and that no significant shrinkage occurs on-mass body thrown against the wall of the container after the mass body has its internal solidification can. Since only a relatively small part received the rate.

The invention is based on an exemplary embodiment

Calcium silicate is formed, the strength is sufficient described in more detail.

such mechanical stresses not. There are 20 40 parts of diatomaceous earth, 22 parts of carbide lime, stoichio-

comes a heavy wear and tear of the surface of the metric calculated as CaO, and 1 part long-fiber

Mass body is formed with detachment of powder asbestos are mixed well and 270 parts of water

shaped particles. added. The water should preferably be

At the same time, the amount of intermediate heating gradually expands, since this accelerates the reaction between the lime space between the inner wall of the container 25 and the silica. Around a settling and the outer side of the mass body. The interstitial particles or removal of the hydrogen space finally assumes such dimensions to prevent or reduce bubbles from solid ones that more heat is released during decomposition. for example ethyl cellulose, sulphite liquor or can be derived. An acetylene gas explosion 30 sugars,
is then inevitable. After the reaction has started, roughly

The invention relates to a method for granular aluminum powder in an amount of 0.25 g

position of a solid mass for acetylene gas container per liter mass added, and the mass is in a

made of calcium silicate, which is filled through a water-containing steel container, in which it undergoes a "fermentation"

is built up mixed, which is exposed to lime or a 35 hydrogen formation. Shortly before full

Contains excess lime-containing substances and at the end of "fermentation" the container is screwed on

Silica or an excess of silica and placed in a heating furnace, where it was 48 bis

containing substance and in which the porosity is exposed to a temperature of 200 ° C for 72 hours

of the built-up solid mass by an excess. After this time, in an oven with the

of water is obtained. 40 same or higher temperature blown off. In addition

With the invention, the above-mentioned are the disadvantages of the container for reducing the pressure avoided. This can be opened in two ways. The water evaporates and is blown out, that are advantageously used at the same time, and the mass becomes porous. Remaining water although it is hardly technically related, it will then stand in an oven for 72 hours. One way is to expel the strength of the 45 gradually increasing temperature. the To enlarge the latticework of calcium silicate, so the temperature of the mass is 270 to 300 ° C that it better counteracts the given tremors.

can stand. The other way is to keep the container with the during drying

To create nits in which the mouth, which is open during hardening, is facing upwards. After cooling down

of the calcium silicate forming spaces 50 of the container with its mass, it is evacuated, and

reduced, in the most advantageous case even to zero acetone in an amount of 0.32 kg per liter volume

be reduced. let in. Then the container is ready to be filled

According to the invention, the mixture before with acetylene gas. This is pumped in, whereby

its solidification takes the stoichiometric amount of it quickly into that present in the container

powdered metal, namely aluminum, 55 acetone dissolves with a simultaneous increase in pressure. at

Magnesium or zinc, added, with the overpressure permitted ^{in a container with 15 kg / cm 2}

Lime existing hydroxyl ion forms a hydroxide dissolves per liter volume of the container about 0.18 kg

and then reacts as an acid, which reacts with the acetylene gas.

released calcium with the development of 40 parts of diatomaceous earth mentioned above hydrogen combines to a salt. It is known that 60 is not critical, provided that the best strength is obtained when such compounds are formed from aluminum, the stoichiometrically correct amount of kieselgur sium and zinc, which is so indeterminate in relation to lime that it has an electrical polarity that their hydroxides in the specified case corresponds to the amount mentioned. Acids can pass over. For example, you can use 20 to 50 parts of silica (Ca (OH) ₂ ) to form aluminum hydroxide gur, without the strength of the mass minium is significantly reduced with the slaked lime 65 present, and if a lower strength is used - (Al (OH) ₃ ) react, which is enough to change its polarity, even 16 to 60 parts of diatomaceous earth can be seen in front of and as acid (H ₃ O ₃ Al) can be seen around.

It is recommended to use a good quality kieselguhr that only contains insignificant impurities, usually does not contain more than 9%. Diatomaceous earth has the advantage over other forms of silicon dioxide, that it consists of diatoms or diatoms, the armor of which is rod-shaped. This leads to they are particularly suitable for building up a lattice within the mass with an increased porosity without favoring a reduction in strength.

In the case of the mass given above, a porosity of 91.5% was found, which means that before Replenishing acetone in the container consisted of only 8.5% of the total volume of solid material.

Asbestos can also be considered a fairly pure silica material. But it contains slightly larger amounts of impurities, primarily magnesium, aluminum and iron compounds, which act catalytically in the formation of calcium silicate, and thereby its strength support financially. As already mentioned, the asbestos should have long fibers, but it does not need the greatest fiber length to have. It is known that asbestos fibers of 20 to 30 cm in length can be made, but For purposes of the invention, a fiber length of 20 to 30 mm is completely sufficient. White asbestos is preferable to colored asbestos, such as green asbestos, although colored asbestos are also used can. The reason is that colored asbestos contains undesirable impurities, which do not occur in white asbestos or only in small quantities. Instead of asbestos, you can use another fibrous mineral. Synthetic mineral fibers can also be used. These Mineral fibers are supposed to prevent the mass from sticking while it is still wet. The amount Asbestos can be varied within narrow limits of 0.4 to 2.5 parts or given Cases even within the limits of 0.3 to 3 parts.

When asbestos is mentioned here and in the following, all fibrous material is included understand which can occur with a fiber length of, for example, 20 to 30 mm and which contains silicon dioxide as the main component. The type of calcareous material is essential for achieving one high strength of the mass is important. It is known that carbide is practically used exclusively made from hydraulic lime, but almost never from Urbergkalk (limestone), and that from Urbergkalk manufactured carbide is inferior. Hydraulic lime retains its reactive properties also during the carbide combustion and during the subsequent extinguishing with the formation of acetylene gas. In addition, however, there is an increase in activity, which is presumably due to rearrangements in the Calcium atom under heat in connection with the production of carbide under extremely high Temperature has arisen. This activity also remains essentially in the calcium atom after Extinguishing the carbide exist during the production of acetylene gas, so that the resulting By-product carbide lime is highly active and has a strong tendency to react with substances containing silicic acid for the production of calcium silicate with a very high internal binding force and consequently higher Shows firmness.

Also with regard to the amount of carbide lime, one does not necessarily follow the instructions given above maximum amounts of 22 parts, calculated stoichiometrically on CaO, must hold. It can while maintaining the strength, 20 to 25 parts can also be provided, and in the case of insignificant Reduced strength, even 16 to 30 parts can be provided.

The high activity of the carbide lime enables it to be used with smaller amounts of unslaked Lime of other origins can be mixed without a noticeable reduction in strength taking place. However, this lime should also preferably be hydraulic.

It has already been mentioned that the porosity in the mass is due to the remaining excess water is produced which does not take part in the reaction, but which is in liquid form at overpressure is held in the oven while the mass cures. This water then accumulates The reason for the hygroscopic lattice structure caused by kieselguhr together with asbestos fibers capillary properties like a network, which is an advantage, since it increases the mass Tends to soak up the acetone poured into it. As a result, the porosity is mainly determined from the excess water, but not from the small amount of aluminum that comes from others Reasons is added. The hydrogen produced by the reaction of the aluminum with the lime is believed to be trapped in bubbles with high surface tension. It can therefore be suspected that the vesicles with high surface tension are not or only slightly hygroscopic and consequently show no tendency to take up acetone. Depending on the desired The degree of porosity can thus be used to change the amount of water.

The following table gives test results with various mixtures, with those given above Parts were converted into% CaO.

component

Mixture 1
% I share

Mixture proportion

Mixture 3
% I share

Mixture 4
»/ 0 I share

Kieselguhr
Lime ....
Water ..
Asbestos ..
porosity

13.1

13.1

73.6

0.2

16
16
90
0.3

12.5

12.5

74.8

0.2 20
20th
120
0.4

11.8
5.9

81.7
0.6

350

2.5

10.5
5.2

83.7
0.6

60
30th
480
3.0

87

88 92

93

It is in the nature of the invention that the force should act, but still be large enough to the amount of aluminum powder seen to generate its expansion pressure so small. It was mentioned must that the resulting hydrogen bubbles not that a good average of aluminum 0.25 g each interferes with the hygroscopically effective porosity liter mass, but depends on the circumstances

this amount can be reduced to 0.1 g per liter of mass or increased to 0.5 g per liter of mass will.

If for the purpose of preventing or reducing settling in the wet mass, glue, for example Ethyl cellulose, sulphite liquor or sugar is added, this can improve the viscosity Agents can be added in the same amount as mentioned for aluminum.

The aluminum should not react directly with the lime, rather it is a delay he wishes. In its first state, the wet mass is rather thin, and it could be disadvantageous if a reaction with aluminum occurs immediately. The generated hydrogen bubbles would then rise up through the mass and exit. A delay in the response can, for example can be achieved in that the aluminum powder is greased before the addition. One Such a layer of fat is only slowly or not at all penetrated by the water until the reaction occurs a temperature increase has occurred between lime and silica. To delay the response of the aluminum, it is ground into a somewhat coarse-grained form. With a suitable grain size the grains should pass a sieve with 0.5 mm mesh size, but through a sieve with 0.1 mm Mesh size are retained.

Instead of greasing the aluminum powder, it can be impregnated with oil, e.g. B. with mineral oil or paraffin. The same effect is achieved if the aluminum powder has been treated in a manner known per se to form a dense gray skin (Al ₂ O _3).

Attempts to produce a solid mass for acetylene gas containers in the manner indicated above have shown that a mass with completely satisfactory strength results, which the interior of the container filled without any gaps between the container wall and the Mass body. At the same time you get a completely satisfactory one Security against explosions through fine capillaries in the bulk and one of that Volume ratio-dependent storage capacity, all of which have so far been more explosion-proof in the field Acetylene gas containers.

Claims (6)

Patent claims: 1. Process for the production of a solid mass for acetylene gas containers from calcium silicate, the by a water-containing mixture of lime or an excess of lime-containing substance and consists of a substance containing silica or a silica in excess, thereby characterized in that the mixture before solidification, the stoichiometric amount of one powdered metal, namely Al, Mg or Zn, is added, which is a hydroxide with the Hydroxyl ion present in the lime forms and forms an acid with the released calcium Development of hydrogen into a salt connects. 2. The method according to claim 1, characterized in that the metal body is coarse-grained are, with a grain size between 0.5 and 0.1 mm. 3. The method according to claim 1 and 2, characterized in that the metal body with a Insulating skin made of fat, oil, paraffin can be enveloped. 4. The method according to claim 1 and 2, characterized in that the grains of the metal with surrounded by an oxide layer. 5. The method according to claim 1 to 4, characterized in that the metal has already been added before a noticeable bond of the mass has taken place. 6. The method according to claim 1 to 5, characterized in that to the mass before binding an adhesive such as ethyl cellulose, sulphite liquor or sugar is added.