Note: Descriptions are shown in the official language in which they were submitted.
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CASE 4413
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A DEVICE_FOR REMOVING HYDROGEN GAS ~ROM THI~ CONTAINMENT
OF A NUCLEAE~ RE~CTOR PLANT
BACKGROUND
The present invention relates to nuclear reactors and more particularly to -
5a device for removing hydrogen gas from the containment of a nuclear reactor
piant by using a thermal recombinator, which is comprised of a metallic housing
and deviation surfaces arranged therein for the flow of gas and which has an
inlet piping for the hydrogen enriched gas mixture as well as an outlet piping
for the hydrogen-poor gas mixture.
10Such a device has been described by the publication "Hydrogen Recombiner .
System" of the Rockwell Company under the publication No. 523K-20 Rev.
8/79. In this system two electrical heating elements are placed in an insulatlngspace. The gas mixture enriched with hydrogen led off from the containment [
flows within the space in a large tubular scroll case. The gaseous mixture is F::
15heated above the hot air in the space and then enters the reaction chamber also
placed within the space. The gaseous mixture, which is now hydrogen-poor --
leaves the insulated space by means of a pipe and after transferring its residual
heat to a heat exchanger, again enters the containment. This type of heating
requires a large floor space. In addition, for reasons for saEety, the device can
20only be operated if the hydrogen content of the gaseous mixture introduced is
less than the concentration above which explosion may occur, i.e.,
approximately four volume percent.
The present invention therefore takes up the problem of producing a device
of the type known initially9 which has a compact heating unit and which permits
25processing all gas mixture concentrations without danger. ~`
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CASE 4413 --~
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SUMMARY OF THE INVENTION
This problem is solved according ~o the present invention by inductively
heating the walls of the housing and the deviation surfaces and by connecting
the inlet piping for the hydrogen-enriched gaseous mixture to the outlet piping -
S for the hydrogen-poor gaseous mixture by means of a three-way valve, whose ---
third outlet conducts a portion of the hydrogen-poor gaseous mixture to the
containment.
~y means of inductive heating, which does not require a great deal of
space, a uniform introduction of heat, with little heat loss, is achieved up to the
deviation surfaces acting as a stationary mixer surface. The gaseous mixture
introduced into the recombinator is reliably maintained below the critical limitof four volume percent hydrogen by diluting the hydrogen-enriched gaseous
mixture with a partial flow of the hydrogen-poor gaseous mixture In the region
of the three-way valve.
The housing of the recombinator is preferably formed as an elongated tube
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unit, which is surrounded at least partially by a water-cooled induction coil.
In order to increase the input of heat, the region of the housing walls ,L":,:,:surrounded by the induction coil is reinforced in its construction and the
deviation surfaces contact the inner surface of the walls in a type of friction
20 connection. Such an effort is obtained by welding the deviation surfaces to athick-walled piece of tubing and forming the friction connection between the - -
peripheral side of the piece of tubing and the inner side of the housing walls.
According to a preferred configuration of the device, the gas flowing into
the connecting pipe between the three-way valve and the containment as well
25 as into the inlet piping in the region between the containment and a
recuperating heat exchanger is maintained, preferably by means of a
supplemental heating unit at a temperature which is higher $han the
temperature prevailing in the containment. This measure has the advantage of
preventing formation of condensate in the piping system and thus there is no
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CASE 4413
development of highly radioactive condensate outside the containment. The
water forming during the combustion of the hydrogen by means of the -
supplemental heater is taken up by the hydrogen-poor gaseous mixture. -
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BRIEF DESCRlPllON OF THE DRAWING
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The sole Figure is a schematic diagram of a nuclear power plant steam !'''.'.'''
system incorporating the preferred embodiment according to the present
invention.
DETAlLED DESCRIPTION OF THE PREFERRFD EMBODIMENT -
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A hydrogen-enriched gaseous mixture, which has formed in an excessive
10 amount in the containment is removed from the containment 1 of a nuclear
reactor plant, not shown in further detail, by means of blower 2 and inlet piping
3 and is fed into recombinator 4. Housing 5 of the recombinator is an elongated
cylindrical tubular unit, which is closed semispherically at both of its ends. In
the cylindrical section of the housing are placed deviation surf aces 6 of
15 stainless steel, which serve as stationary mixing surfaces. The upper half of the
housing is inductively heated by water-cooled coil 7. In this way swirling flow is
induced also by deviation surfaces 6 as well as by housing wall 8, so that a
homogeneous temperature distribution is assured. Insulation 13 introduced on
the cylindrical section of housing 5 protects the induction coil from too high a20 heat load. The self-heating of the induction coil is led off by means of cooling
circuit 14. The cooling circuit is provided with checkpoints 15, 16, recuperating
heat exchanger 17, cut-off armature 18 and control armature l9. It is
connected to a piping system, which is not shown, by quick-action stop coupling
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CASE 4413
20. In the region oE induction coil 7, deviation surfaces 6 are welded to thick-walled piping piece 9, which enters into a -type of friction connection with itsperiphery extending to the inside of housing wall 8 and contacting this wall. Aneffective introduction of heat is achieved by this intimate connection. The
upper half of the recombinator serves for heating up to the operational
temperature of seven hundred to seven hundred fifty degrees Celcius. The time
it takes for the complete reaction of the hot gaseous mixture in the lower half
amounts to approximately one half (0.5) second. A homogeneous temperature
distribution is achieved ~y the appropriate confi~uration of the deviation
surfaces. With a flow rate of one hundred eighty cubic meters per hour (in the
normal state), approximately fifty liters total volume of the recombinator is
necessary in all for a total time of one second. This volume is achieved, for
example, by housing 5, which is comprised of one and one half meter long tube
of nominal width of twenty five centimeters. After combustion has been
achieved, the now hydrogen-poor gaseous mixture leaves the recombinator via
outlet piping 10. The necessary heating power of induction coil 7 is controlled
by means of temperature checkpoint 11. The gaseous mixture gives up a part of
its heat by flowing through recuperating heat exchanger 12. In this way the
gaseous mixture flowing into inlet piping 3 is preheated. The gaseous mixture
found in outlet piping 3 is cooled to sixty to sixty-five degrees Celcius in
counterflow in recuperating heat exchanger 17. Control armature 19 placed in
the cooling circuit for the induction coil, to which recuperating heat exchanger17 is connected, controls the flow-through quantity of coolant. The desired
temperature of the gaseous mixture passing through heat exchanger 17 in
counterflow can therefore be controlled in a simple way. ~he gaseous mixture
cooled for the time being now reaches remote-controlled three-way valve 21.
From here most of the hydrogen-poor gaseous mixture flows through outlet 22
of the three-way valve and pipe-line 23 through flame arrester 34 and arrives
back at containment 1. The remainder of the gaseous mixture goes through
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connection pipe 3a to inlet piping 3 and serves to thin the hydrogen-enriched ::
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CASE 4413
gaseous mixture coming from the containment. The quant;ty of the gaseous
mixture brought through connecting pipe 3a depends on the hydrogen content of
the gaseous mixture coming from the containment. It is con~rolled in such a
way by the three-way valve that the gaseous mixture reaching the recombinator
5 is always less than four volume percent hydrogen. A dangerous explosion is thus
reliably preYented~ Flowmeter units 27, 38, pressure gau~e units 29, 30, 31,
temperature sensors 32, 33, and flame arrester 34 are incorporated. Pipe 23 is
heated by means of a not-shown supplementary heating unit in order to keep the
gaseous mixture at a temperature of sixty to sixty-five degrees Celcius. In this10 way it is assured that no condensate can form in the gaseous mixture prior toreaching the containment. In addition, the region of the inlet piping 3 between
containment 1 and recuperating heat exchanger 12 is provided with a
supplementary heating unit, not shown. l he temperature of the gaseous
mixture flowing therein is thus kept at a higher value than the temperature
15 measured within the containment. Just as for pipe 23, this measure will present
the possibility of any incidence of highly radioactive condensate occurring
outside the containment. Decontamination of the device can be achieved
simply with a liquid or gaseous flushing medium by means of comlections 24, 25,
which are shown only up to the quick-action stop couplings 20 and which are
20 provided with cut-off armatures 2~
The above description and drawings are only illustrative of one embodiment
which achieves the objects, features and advantages of the present invention
and it is not intended that the present invention be limited thereto. Any
modifications of the present invention which come within the spirit and scope
25 o~ the following claims is considered part of the invention.
What is claimed as new and desired to be secured by Letters Patent of the
United States is:
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