Siemens Aktiengesellschaft

Kraftwerk Union Aktiengesellschaft

Willi Bette

Hans-Jurgen Cirkel

Josef Lersch

Karl Strasser

Reinhard Muller

Arno Mattejat

Dirk Friede

Detlev Coerlin

Herbert Stenger

Ottmar Voitlein

Walter Stühler

Christian Merkel

Regina Hornung

Volker Bruckner

Reinhard M/u/ Ller

Hans-J/u/ Rgen Cirkel

Karl Straßer

During the operation of a fuel-cell assembly, the latter is supplied with ambient air with the aid of a liquid ring pump. Any foreign matter that is contained in the air is taken up by the service fluid of the liquid ring pump. The charging of the service fluid with foreign matter is controlled. In particular, the service fluid is continuously conducted in an circuit via a purification device.

Method for operating a fuel cell system and fuel cell system

A fuel cell module includes a number of series-connected fuel cells which collectively form a fuel cell stack in such a way that the magnetic field or stray field that is generated during the operation of the fuel cell module and that is detectable in an outer area is kept particularly small. To this end, the invention provides that a number of shielding lines that are connected to a first pole flange of the fuel cell stack are provided, these shielding lines being guided on the outer area of the fuel cell stack, as far as a contact area to a second pole flange of the fuel cell stack.

Fuel cell module

A fuel cell installation includes a cascaded fuel cell block, for essentially waste gas-free operation. An installation of this type presents the problem that the cascaded fuel cell block is complex to produce and therefore expensive. To solve this problem, the fuel cell installation has several steps which are arranged in a cascade, each of the steps comprising one or more non-cascaded similar fuel cell blocks. A fuel cell installation construction including modular similar fuel cell blocks is economical and simple to produce in series.

Cascade fuel cell system

A leak in a fuel cell module can allow hydrogen and/or oxygen to escape from the fuel cell module, thereby creating a high risk of fire or explosion. This problem is addressed by providing a fuel cell installation with a fuel cell module that is enclosed in a gas-tight pressure container. Filling the pressure container with a protective gas ensures that if the fuel cell module does leak, no operating gas can escape from the module, with protective gas entering the module instead. A leak therefore no longer poses a risk. The leak can also be identified and located by a voltage drop in the cells affected by the leak.

Fuel cell installation

A method for operating a fuel cell plant and a fuel cell plant are provided. The thermal efficiency of a fuel cell plant results from the useful heat which is generated per quantity of fuel. Heat which is radiated from the fuel cell plant into the environment is lost and cannot be utilized. The method minimizes the radiation of heat from the fuel cell plant. Air for operation of the fuel cells is passed into a housing which surrounds heat-radiating components of the fuel cell plant. The air flows around the components, absorbs the heat which is radiated and delivers it to the fuel cell block, where the heat is emitted to cooling water that cools the fuel cell block and transfers the heat to water of a heating-water circuit.

Method for operating a fuel cell plant and fuel cell plant

A method for identifying a gas leak between anode and cathode gas areas of a PEM fuel cell includes detecting a cell voltage. The anode and cathode gas areas are purged with nitrogen in a first time period. The cathode gas area is filled with oxygen and the anode gas area is filled with hydrogen in a second time period. A drop in the cell voltage below a limit value as a function of time is then measured and evaluated. The method ensures reliable identification of the gas leak. A fuel cell system operating according to the method is also provided.

Method for identifying a gas leak, and fuel cell system

A process for operating a PEM fuel cell installation includes providing at least one PEM fuel cell module having an inlet valve for hydrogen H.sub.2 and an inlet valve for oxygen O.sub.2. In order to switch off the PEM fuel cell module, the oxygen O.sub.2 inlet valve is closed in a first step, and the hydrogen H.sub.2 inlet valve is closed in a second step when a predetermined oxygen O.sub.2 partial pressure at a cathode part of the PEM fuel cell module is reached. Reliable operation of the PEM fuel cell installation is guaranteed by this measure.

Process for operating a PEM fuel cell installation

In a method for adjusting the removal of inert gas from a fuel cell block having a number of fuel cells, a progressive rise in a proportion of inert gas results in a cathode-side or anode-side gas mixture flowing through the fuel cells. An inert-gas-rich gas mixture is drained out as a function of a voltage drop, and the voltage drop is measured between at least two immediately adjacent fuel cells. A fuel cell block includes a number of adjacent fuel cells having electrodes and gas chambers. At least one bipolar plate contacts the electrodes of adjacent fuel cells over a large area. Two spaced-apart contacts are disposed between at least two of the adjacent fuel cells on the at least one bipolar plate. A control element for a gas mixture leaving one of the gas chambers and having a high proportion of inert gas, is adjusted by a voltage drop picked up at the contacts.

Fuel cell block and method for adjusting the removal of inert gas from

Preionization is important for the generation of a homogeneous glow discharge in the gas space of a laser chamber between laser electrodes. TE type excimer lasers operate especially with X-ray preionization, for which high voltage pulses are needed. According to the present invention, the voltage pulses are obtained by means of an auxiliary circuit that includes a branch which is connected in parallel with a high voltage switch or with the laser discharge gap and which incorporates a saturable magnetic inductance and the primary winding of a high voltage pulse transformer connected in series therewith. The high voltage triggering pulses for the preionization element, which is an X-ray tube in particular, are generated in the secondary winding of the transformer. If the branch is connected in parallel with the high voltage switch it also has a series capacitor. If it is in parallel with the laser discharge gap then the branch has a shunt capacitor. In this way, the timing of the preionization and in particular the X-ray pulse, can be adjusted precisely in relation to the voltage rise time through the laser electrodes and in relation to the laser.

Device for pre-ionization in discharge-pumped gas lasers, in particular

An apparatus and method for generating high-power, high-voltage pulses for a laser having laser electrodes with an electrode path includes at least one charge unit. A pulse-generating network has an input side connected to the at least one charge unit and an output side connected to the laser electrodes. The pulse-generating network has a first branch and a second branch connected parallel to one another and connected to the laser electrodes. The first branch has a first charge capacitor with a relatively high capacitance and a magnetic switch in the form of a saturatable inductor connected in series with the first charge capacitor. The second branch has a second charge capacitor with a relatively low capacitance. A trigger branch is connected parallel to the electrode path. The trigger branch has at least one high-voltage switch and an in-series inductance. The high voltage switch serves as a trigger for initiating a saturation of the magnetic switch and a discharge of the first charge capacitor through the saturated magnetic switch into the laser electrode path.

Apparatus and method for generating high-power, high-voltage pulses,

A preinoization device, in particular for X-ray preionization in discharge-pumped gas lasers, especially excimer lasers, is connected to a pulse generating network of an excitation circuit for gas lasers. A high voltage pulse transformer has a primary winding connected between a storage capacitor and a high-voltage switch in the pulse generating network. The pulse transformer emits preionizing pulses on the secondary side that lead to the firing of the laser glow discharge for a preionizing device, in particular an X-ray tube. The pulse transformer is constructed for this purpose as a saturable magnetic inductor with at least one secondary winding. If the high voltage switch is closed, when the pulse transformer is unsaturated its primary winding has its maximum inductance, so that there will be a secondary side voltage pulse at this time because of the law of induction. After a pre-set delay or retardation time of 50-100 ns, for example, the core will be saturated, the inductance of the primary winding will drop rapidly, and the full current will flow within the inversion circuit, so that the full high voltage builds up on the laser electrodes in order to fire the glow discharge.

Preionizationd device, in particular for x-ray preionization in

An excitation circuit for TE lasers serves to generate a homogeneous high pressure glow discharge between laser electrodes within a gas space of a laser chamber. A fast acting high voltage switch of a pulse forming network is a multi-channel pseudo-spark switch and is preferably integrated with the laser. The switch is formed of a parallel circuit including a number of individual pseudo-spark switches with gaps. The total multi-channel pseudo-spark switch is filled with an ionizable low pressure gas filling at a given pressure. Voltage is applied to the anode and the cathode in such a way that the resulting gas discharge is located on the left-hand branch of the Paschen curve. The switch of the excitation circuit can also be used as a separate structural element for triggering an electrical high voltage switch circuit, and also for so-called flat plane laser systems.

Multichannel pseudo-spark switch and excitation circuit for gas lasers

A high-energy TE laser system, includes an excitation circuit, a laser head having an optical axis, a laser chamber with a gas space formed therein, at least two laser electrodes being disposed opposite each other and spaced apart in the laser chamber parallel to the optical axis of the laser head for producing an arc-free capacitor discharge between the electrodes being as homogenous as possible in the gas space for excitation, at least one rapid high-voltage switch, a pulse-forming network connected to the rapid high-voltage switch for producing high-voltage pulses at the laser electrodes with the rapid high-voltage switch, the pulse-forming network including first and second strip conductor capacitors respectively associated with the rapid high-voltage switch and with the laser head, the strip conductor capacitors including plates and dielectric layers disposed between the plates extended substantially normal to the optical axis of the laser head, forming a capacitor stack stacked substantially parallel to the optical axis of the laser head, the plates being connected in the pulse-forming network, the pulse-forming network being a Blumlein circuit in which at least one plate of the second strip conductor capacitor is connected to one of the laser electrodes, and the plates being divided into n adjacent plate sections having n-1 partings respectively disposed therebetween, and coupling inductances conductively connecting the plate sections to each other. Otherwise, the pulse-forming network is a charge-transfer circuit in which at least a partial surface of the plates of the first and second strip conductor capacitors are connected in common to one of the laser electrodes.

High-energy laser system

A high-power pulse transformer for short, high-voltage and/or high-current pulses includes:

High-power pulse transformer for short high-voltage and/or high-current

A high-energy TE laser system, includes an excitation circuit having supply lines, a laser head having an optical axis, a laser chamber with a gas space formed therein, at least two laser electrodes being disposed opposite each other and spaced apart in the laser chamber parallel to the optical axis of the laser head for producing an arc-free capacitor discharge between the electrodes being as homogeneous as possible in the gas space for excitation, at least one rapid high-voltage switch, a pulse-forming network connected to the rapid high-voltage switch for producing high-voltage pulses at the laser electrodes with the rapid high-voltage switch, the pulse-forming network including first and second strip conductor capacitors respectively associated with the rapid high-voltage switch and with the laser head, and the pulse-forming network including first and second equivalent inductances of the excitation circuit formed of self-inductances of the high-voltage switch, the laser head, the supply lines of the excitation circuit and the strip conductor capacitors, the pulse-forming network being a Blumlein circuit for a given maximum build-up time of the high-voltage pulses produced at the laser electrodes, the first strip conductor capacitor having a capacitance being less than the capacitance of the second strip conductor capacitor by a factor k&lt;1, and the first equivalent inductance being connected in series with the first strip conductor capacitor and having an inductance being greater than the inductance of the second equivalent inductance by a factor .sup.1 /k. The pulse-forming network may also be a charge transfer circuit.

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Erlangen, Germany

Willi Bette