Chemical apparatus and process disinfecting – deodorizing – preser – Chemical reactor – Waste gas purifier
Reexamination Certificate
1999-01-05
2001-08-14
Tran, Hien (Department: 1764)
Chemical apparatus and process disinfecting, deodorizing, preser
Chemical reactor
Waste gas purifier
C422S171000, C422S172000
Reexamination Certificate
active
06274098
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to improvements in an apparatus for the treatment of exhaust gases containing hydrogen, in particular exhaust gases from facilities and equipment such as semiconductor manufacturing plants and chemical plants that employ hydrogen in their processes.
BACKGROUND OF THE INVENTION
Exhaust gases containing hydrogen from facilities and plants such as semiconductor manufacturing facilities and chemical plants are generally disposed of by burning at high temperatures in incinerators.
FIG. 5
shows a typical prior art high-temperature combustion disposal apparatus used in semiconductor manufacturing facilities. In this apparatus, exhaust gas A containing hydrogen from semiconductor manufacturing line B, which includes a hydrogen annealing furnace, is first led into a quartz furnace
50
containing an ignition silicon chip
52
which is heated by a heating lamp
53
. Hydrogen in the exhaust gas A gushing out of a nozzle
51
is then subject to complete combustion at approximately 1800 to 2000° C. in the quartz furnace
50
.
Quartz furnace
50
has another pipe
54
connected thereto. Oxygen is fed into the quartz furnace
50
through the pipe
54
to assist in complete combustion of the hydrogen. In order to ensure complete combustion of the hydrogen and to ensure safety, the amount of oxygen to be fed into the furnace is set at more than half of the amount of hydrogen.
In treatment of exhaust gases containing hydrogen by an external combustion unit C as shown in
FIG. 5
, the exhaust gas A can be burned completely with high efficiency in a relatively small external combustion unit C, provided that the exhaust gas A containing hydrogen flows from the semiconductor manufacturing line B at a nearly fixed rate and that the concentration of hydrogen in the exhaust gas A does not fluctuate too much. However, the disposal technique employing the aforesaid external combustion unit C has a fundamental drawback in that unstable combustion due to fluctuations in the discharge amount of exhaust gas A or changes in the concentration of hydrogen in the exhaust gas A could result in an explosion of the external combustion unit C.
If, for instance, the flow rate of exhaust gas A containing hydrogen from the semiconductor manufacturing line decreases, with the level of hydrogen dropping and staying at almost nil longer than a specific time, then the combustion flame near the tip of the nozzle
51
will go out, with the temperature dropping near the tip of the nozzle
51
. Unless ignition silicon chip
52
is heated again, combustion will not be resumed, even when the flow rate of the exhaust gas A and the concentration of hydrogen rise again. Hydrogen-containing gas A would then be discharged untreated out of the combustion unit C, bringing about a very dangerous situation.
Another problem is that if the discharge rate of exhaust gas A drops substantially, backfire may spread toward the semiconductor manufacturing line B from the external combustion unit C through the pipe line
55
. In this circumstance, there will arise a danger of explosion of the semiconductor manufacturing line B itself.
To ensure safety, the prior art combustion unit C is equipped as a matter of course with various safety measures. The safety measures include an alarm, an automatic igniter, and an automatic gas shutoff device that will work when the combustion flame of the mixed gas from nozzle
51
goes out. But if those safety measures are actuated each time the combustion flame in the external combustion unit C goes out or the combustion becomes unstable, operation of the semiconductor manufacturing line B will be affected, which can have an adverse effect on the quality of semiconductor products.
In another environment, at nuclear power stations, when the reactor coolant water is decomposed by radiation, a hydrogen-oxygen mixture is generated in the coolant water. This hydrogen-oxygen mixture is recombined using a catalyst. The principle of that recombination technique as disclosed in unexamined Japanese patent application 57-049895 is this, with reference to FIG.
6
: The hydrogen-oxygen mixture A separated by an air extractor D from coolant water E is first mixed with a large quantity of steam S to produce a mixture A
0
whose concentration of hydrogen is below the explosion limit. This mixture A
0
is then led to a recombiner
60
including a catalyst unit
61
provided therein through an upper nozzle
62
where hydrogen and oxygen are recombined into steam through catalytic action at a specific high temperature. The steam thus produced is then discharged through a lower nozzle
63
.
However, the technique outlined in
FIG. 6
is for the treatment of large quantities of a mixture fluid A
0
mixed with large quantities of steam S. The recombiner
60
becomes so large in size that it is difficult to install in semiconductor manufacturing facilities. In addition, because the rate of reaction between hydrogen and oxygen in the recombiner
60
is relatively low, unreacted hydrogen is discharged out of recombiner
60
through lower nozzle
63
. A complete treatment of the unreacted hydrogen discharged from recombiner
60
in turn requires a separate external combustion unit, which means additional and substantial investment in equipment.
SUMMARY OF THE INVENTION
The present invention addresses the aforesaid problems encountered in the prior art treatment of gas containing hydrogen in facilities such as semiconductor manufacturing plants. Among those problems are:
(1) If the discharge amount of the exhaust gas containing hydrogen and the concentration of hydrogen in the exhaust gas fluctuate, combustion becomes unstable or combustion flames go out. As a result, the gas containing hydrogen can accumulate, resulting in explosion of the external combustion unit.
(2) There is danger that a backfire may spread from the external combustion unit into the semiconductor manufacturing line, causing damage to the facilities when the discharge amount of the gas containing hydrogen decreases.
(3) Unstable combustion in the external combustion unit could affect the operation of the semiconductor manufacturing line, lowering production efficiency or causing non-uniformity in product quality.
It is an object of the present invention to provide an apparatus for the treatment of exhaust gases containing hydrogen, which apparatus permits complete treatment of gases containing hydrogen from a semiconductor manufacturing line on a constant and steady basis regardless of the flow rate, i.e., the discharge rate of the gases, and regardless of the concentration of hydrogen therein, such that the treatment proceeds without adverse effects on the semiconductor manufacturing line and with no need for mixing the exhaust gases containing hydrogen with steam or the like for dilution.
The present invention in a first embodiment provides an apparatus for the treatment of exhaust gases containing hydrogen, which apparatus comprises an ejector-type vacuum generator having a suction port connected to a discharge source of exhaust gases containing hydrogen and having a drive fluid supply port connected to an oxygen supply source, a hydrogen-oxygen reactor provided with a catalyst and connected to a drive fluid discharge port of the vacuum generator, and a drain reservoir connected to an outlet of the reactor for storing water discharged from the reactor. A second hydrogen-oxygen reactor provided with a catalyst and connected to an outlet port of the drain reservoir and a second drain reservoir connected to an outlet of the second reactor for storing water discharged from the second reactor may be additionally provided.
The present invention in another embodiment provides an apparatus for the treatment of exhaust gases containing hydrogen, which apparatus comprises an ejector-type vacuum generator having a suction port connected to a discharge source of exhaust gases containing hydrogen and having a drive fluid supply port connected to an oxygen or air supply source, a hydrogen-oxygen reactor provided with a catalyst a
Hirao Keiji
Ikeda Nobukazu
Kawada Koji
Minami Yukio
Morimoto Akihiro
Fujikin Incorporated
Griffin & Szipl, P.C.
Tran Hien
LandOfFree
Apparatus for the treatment of exhaust gases by combining... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus for the treatment of exhaust gases by combining..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus for the treatment of exhaust gases by combining... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2527480