Ozone pipe for ozone production plant

An ozone pipe is provided for use in a large production plant employing a large number of such pipes in parallel. The pipe of the invention avoids the usual drawbacks for such pipes in large plants in having the metal electrodes melt without discharge of the fuse, or having the fuses discharge in a large number of pipes simultaneously without any indication in the glass pipes of the cause. The above is achieved by the use of a fuse with a capacity within the range of between about 0.63 and 0.15 amperes, and by providing a resistance in each tube mounted in series with the fuse in the power supply.

BACKGROUND AND STATEMENT OF THE INVENTION 
The invention refers to an ozone pipe for use in an ozone production plant, 
wherein a plurality of ozone pipes are connected in parallel. Each is 
provided with a tubular dielectric material encased by a metal jacket 
electrode, as well as with a high voltage fuse arranged in the interior of 
the dielectric material and interpolated into the current supply leading 
to the metal coating of the dielectric material. The high voltage fuse 
switches off the respective ozone pipe in case of electric overload. The 
fuse is combined into a structural unit with the dielectric material and 
the contacts for the current supply. 
In the past, it was customary to provide such an ozone pipe with a high 
voltage fuse arranged in the interior of the tubular dielectric material, 
as shown in German DE-PS 1 085 860. The fuse consists essentially of a 
fusion conductor interpolated between the current supply and the metal 
coating of the dielectric material. 
The high voltage fuse guarantees keeping the plant in working order, even 
during failure of one or several ozone pipes. If short-circuits occur, 
such as due to bursting of the dielectric material, formation of dust 
bridges or moisture deposits between the electrodes, etc., the fusion 
conductor is destroyed by the resulting electric charge exceeding the 
normal value, thus switching off or disconnecting the respective ozone 
pipe from the circuit. 
Experience has shown that conventional ozone production plants, in the 
past, provided, for example, with a cutoff current of 1 A in high voltage 
fuses of the kind mentioned, functioned without any disturbances. However, 
in the presently constructed larger plants with a great number of ozone 
pipes--in the order of several hundred--the following disturbances have 
arisen in series without any discernible reason being understood at the 
present time: 
(a) metal electrodes were melted by an electric arc without the fuses first 
being activated; and 
(b) fuses were activated in large numbers with intact glass pipes. 
The melting of metal electrodes without cutoff of the circuit by the fuses 
leads one to conclude that the quick 1 A fuses utilized were too large, 
while the disconnecting of intact glass pipes points to an insufficient 
dimensioning of the same fuses. 
When investigating these problems in an ozone production plant with 300 
ozone pipes of 15,000 volts, a medium effective current of 230 vA per 
pipe, whereby the high voltage fuses consisted of fusion conductors of a 
cutoff current of 1A, the following was found: Due to the transformer 
dimensioned in accordance with the size of the plant, if a glass pipe 
suddenly becomes defective, there was, at the breaking point of the glass, 
a much greater energy in the form of an electric arc transmitted to the 
metal pipe than was the case in the smaller plants. The given rated 
voltage and an increased rated current result in an output transmitted by 
the electric arc of about 25 kW. The current-time period characteristic of 
a 1 A fuse, however, indicates that the cutoff with a 1.7 rated current 
only takes place after 10 minutes. This makes the power transmitted to the 
metal pipe by the electric arc sufficient to melt the pipe without having 
the fuse disconnect in time. 
When investigating the second undesired condition, it was found that the 
fuses disconnect the circuit with intact glass pipes, if sufficient 
individual charges otherwise statistically distributed over a period 
coincide at one point in time. The frequency of the periodic coincidence 
of individual charges at one point in time increases naturally with the 
number of the ozone pipes, so that large ozone plants are more 
susceptible. In such a case, the condenser or glass pipe which has been 
partially to completely discharged, acts with the presently existing high 
voltage as a short-circuit, and the resulting charges, brief but extremely 
high, destroy the fuse. The type of damage to the fuses would point to the 
conclusion that the peak current values may reach several hundred amperes. 
It is the object of the invention to provide an ozone pipe of the type 
mentioned initially, which is constructed to increase substantially the 
safety of operation in a large ozone production plant. In particular, on 
the one hand, the fuse provides a safe decoupling of individual pipes in 
the case of a disturbance, thus avoiding melting of the metal electrode, 
and on the other hand, any unwarranted cutoff of intact pipes is 
eliminated. 
The invention accomplishes this in an ozone production plant with a large 
number of ozone pipes--on the order of several hundred--by providing each 
ozone pipe with a high voltage fuse with a cutoff current of 0.63 to 0.15 
A. (amperes), and additionally with a resistance being provided in series. 
By the arrangement of resistances, the occurrence of high peak currents is 
limited by means of electric compensation processes between the glass 
pipes. Simultaneously, this provides the solution to the second problem, 
in that the melting of metal tubes is avoided without interrupting the 
circuit by means of the fuse. The high voltage fuses of lower cutoff power 
are utilized, guaranteeing certain cutoff of the individual pipe with a 
short-term overload. 
Of particular advantage is the use of elements which change their 
resistance depending on the current, such as cold conductors or 
semi-conductors. This guarantees smooth operation of an ozone production 
plant. The additional energy requirement caused by the resistance amounts 
to about 2 to 3%. This increase in operating costs is negligible in view 
of the previously occurring damages. 
Since the arrangement of the pipe with the additional resistance permits 
the generation of additional heat, the pipe is cooled without the use of a 
supplemental cooling agent. The front of the glass pipe forming the 
dielectric material, on the end facing away from the current supply, has a 
nozzle for the supplied medium or agent to be ozonized (air and/or gas). 
The glass pipe is open at the current supply end, and the annular 
discharge chamber between the glass pipe and the metal electrode serves as 
return line for the medium emerging from the glass pipe. 
The invention is explained by means of the attached schematic drawings.

DETAILED DESCRIPTION OF THE INVENTION 
As shown in FIG. 1, ozone pipe 10 is shown and 2 stands for a tubular 
universally closed dielectric material consisting of glass which is 
supported in a metal jacket electrode 1 by means of a fixture, not shown. 
The dielectric material 2 is provided with a metal coating (high voltage 
counter electrode) 3 at its interior jacket surface. To transmit the high 
voltage from the supply to the metal coating 3, brushes 11 are arranged in 
the interior of the dielectric material. A high voltage fuse 4 is 
connected in the current supply to the brushes 11. The example shown has a 
high voltage fuse with a cutoff current of 0.2 A. A resistance in the form 
of a cold conductor 5 is connected between the high voltage fuse 4 and a 
contact 6 for the current supply. 
FIG. 2 shows an ozone pipe 20 which is essentially formed as the ozone pipe 
10 according to FIG. 1, the difference being that the glass pipe 2 forming 
the dielectric material has a passage. The end of the glass pipe facing 
away from the contact 6 is provided with a nozzle 8 through which the 
medium 22 (air and/or gas) to be ozonized is supplied. The medium leaves 
at the other open end of the glass pipe, changes direction, is guided 
through the discharge chamber 9 between the glass pipe and the metal 
electrode 1, and leaves the ozone pipe 20 in the area of the nozzle 8, as 
shown by arrows 21.