Gas detection device and gas detection process with a detector and with a modulator

A process for the automatic monitoring of an area for the presence of a combustible target gas, the process comprising the steps of:

• providing a gas detection device, the gas detection device comprising:
• a detector;
• a modulator;
• a modulator chamber enclosing the modulator and being in fluid connection with the area to be monitored;
• a detector chamber, the gas detection device having an inner fluid connection between the modulator chamber and the detector chamber, wherein the detector chamber is configured to receive fluid from the modulator chamber directly via the inner fluid connection, the detector chamber separating the detector from the area to be monitored, except for the inner fluid connection, such that the detector chamber provides a gas-tight separation of the detector from the area to be monitored or a cross-sectional area of a fluid connection between the detector chamber and the area to be monitored is at most 25% of the cross-sectional area of the inner fluid connection;
• a detector sensor arrangement comprising a detector sensor;
• and a signal-processing analysis unit;
• the process comprises the steps of
• applying an electrical voltage to the modulator to heat a modulator component of the modulator as a function of the applied voltage such that the temperature of the modulator oscillates over time and the heating of the modulator component brings about an oxidation of a target gas, which is located in the modulator chamber, as a function of the temperature of the modulator;
• applying an electrical voltage to the detector to bring about a heating of a detector component of the detector as a function of the electrical applied voltage, wherein the temperature of the detector is increased by the application of the electrical voltage and does not oscillate over time at all or oscillates with a lower amplitude than the temperature of the modulator in a predefined analysis period, the heating of the detector brings about an oxidation of a target gas, which is located in the detector chamber, as a function of the temperature of the detector, an oxidation of a target gas in the detector chamber brings about an increase in the temperature of the detector;
• with the detector sensor, measuring a detection variable of the detector wherein the detection variable is the detector temperature or a parameter of the detector which detector parameter correlates with the detector temperature;
• checking whether the detection variable of the detector oscillates synchronously with the oscillation of the modulator temperature in the analysis period;
• and
• determining that the combustible target gas is present in the area upon a synchronous oscillation over time of the detection variable being detected.

A gas detection device for monitoring an area to be monitored for the presence of a combustible target gas, the gas detection device comprising:

• a detector chamber,
• a modulator chamber in fluid connection with the area to be monitored;
• a detector configured such that an application of an electrical voltage to the detector brings about a heating of a detector component of the detector as a function of the electrical voltage being applied to the detector, the heating of the detector component brings about an oxidation of the target gas located in the detector chamber as a function of the temperature of the detector component and an oxidation of a target gas in the detector chamber increases the temperature of the detector;
• a modulator enclosed by the modulator chamber and configured such that an application of an electrical voltage to the modulator brings about a heating of a modulator component of the modulator as a function of the electrical voltage being applied to the modulator and the heating of the modulator component brings about an oxidation of a target gas located in the modulator chamber as a function of the temperature of the modulator component;
• the modulator chamber having an inner fluid connection between the modulator chamber and the detector chamber, the detector chamber separating the detector from the area to be monitored, except for the inner fluid connection, such that the detector chamber provides a gas-tight separation of the detector from the area to be monitored or a cross-sectional area of a fluid connection between the detector chamber and the area to be monitored is at most 25% of the cross-sectional area of the inner fluid connection, wherein the detector chamber is configured to receive fluid directly from the modulator chamber only via the inner fluid connection;
• a detector sensor arrangement comprising a detector sensor configured to measure a detection variable of the detector wherein the detection variable is the detector temperature or a parameter of the detector which detector parameter correlates with the detector temperature, wherein the gas detection device is configured:
• to apply an electrical voltage to the modulator such that the temperature of the modulator oscillates over time as a modulator temperature oscillation;
• to apply an electrical voltage to the detector such that the temperature of the detector, which detector temperature is increased by the application of the electrical voltage, does not oscillate over time at all or oscillates with a lower oscillation amplitude than the oscillation of the temperature of the modulator in a predefined analysis period;
• and
• a signal-processing analysis unit configured:
• to check whether or not the detection variable of the detector oscillates during the analysis period synchronously with the modulator temperature oscillation as a detection variable synchronous oscillation;
• and
• to determine that the target gas is present in the area to be monitored upon detecting the detection variable synchronous oscillation.