SU5938A1 - Method and apparatus for detecting explosive gases in mines - Google Patents

Description

The proposed method and device are intended to detect explosive gases in mines by means of a body heated by an electric current, which, when introduced into the space containing a mixture of air and combustible gases, is heated. According to the degree of incandescence, it is possible to judge approximately the amount of methane in the air.

If the absorbing body (wire) is heated to the ignition temperature of gases and, in addition, is supplied with enough oxygen, besides methane, the absorbed methane burns on the surface of the body through its connection with the surrounding oxygen, and heat develops. Since the new combustible gas constantly flows into the absorbing body and burns there, the wire is under the influence of elevated temperature. This combustion of the absorbed gas begins, according to the author, already at a temperature at which the gas does not ignite under normal conditions. In the case of the interaction of hydrogen and ordinary platinum wire, this process occurs even when it is heated to 250 °, but for methane this does not take place yet. The catalytic body must be made particularly sensitive through preparation. This preparation is that known noble metals, such as palladium or iridium, are deposited in a porous form on the wire.

The temperatures produced by the combustion of methane are very high and therefore it is necessary to take appropriate measures so that the catalytic body does not melt. For this purpose, platinum alloy wire with noble metals of the same group is used. In addition, in order to avoid too high a temperature, it is necessary that the above

the wire was of sufficient thickness. With a wire thickness of 0.06 to 0.08 mm. Dei: Tvie is still quite intense, and the removal of heat is sufficient to prevent the wire from burning out.

Ambient air must have access to the catalytic wire, but the heated wire must not ignite explosive gases. The wire does not actually ignite explosive gases, since carbon dioxide develops during the combustion of methane, which thus surrounds the wire and prevents it from igniting.

In addition, the wire is enclosed in a small chamber that is covered with walls that allow gas to pass through well. The walls of the device are arranged in such a way that ambient air can quickly enter the chamber, and the products of combustion (carbonic acid and steam) cannot quickly escape.

The drawing shows a longitudinal section of the proposed device.

The proposed device uses an ordinary incandescent bulb, in which a glass bell has many openings and in which instead of a normal wire (usually used in an incandescent bulb), a strongly catalytically active wire G is used, which in some parts consists of the above {according to the foregoing) prepared platinum alloys. This bulb is inserted into an ordinary frame through which current is passed to the glow wire. The lamp is located in a room that is formed by cylinder M and porous walls 5 and 5 arranged against each other. Asbestos sealing rings are placed between the walls and the glass cylinder. All parts are connected by a metal casing, which has cutouts in the middle for observing the glow wire.

The bottom wall 5 is located on the base, with an intermediate ring Z placed between them, through which the gas mixture can penetrate into the combustion chamber. The glow wire receives current from a battery located in the IJ stand. Before the glow wire, the resistance is turned on, which is so calculated that it either does not shine at all or it only slightly shines (slightly reddens), and the special parts of the wire, due to the large cooling surface, remain dark.

If the device is brought into a room in which the air contains a few percent of methane, the red-colored special part of the wire, which was still dark, will begin to glow. If the methane content is from 4 to 8%, then the individual parts of the wire are heated white. If methane is greater than 8%, then specially prepared parts of the wire remain red hot even when the current is completely off.

The resistance connected in series with the hot wire supports, in addition, a constant current strength when the electrical resistance changes when the wire G is heated.

With an appropriate choice of additional resistance, with a given battery voltage and the corresponding wire length G, the relationship can be so chosen that strong heating and melting of the wire can be avoided.

The subject of the patent.

1. A method for detecting explosive gases in mines, characterized in that the body G, which absorbs the shallow gases, is heated with an electric current so that, after its introduction into the space containing the mixture