Scanned 1-D gas analysis camera having a line pixel weighted for wind speed
A gas concentration image (i.e., concentration vs. position data) in a cross section through a gas plume is obtained. Such measurements can be obtained by using a 2D array of gas sample inlets, or by moving a 1D array of gas sample inlets through the gas plume. By combining a gas concentration image with ambient flow information through the surface of the gas concentration image, the leak rate (i.e., gas flux) from the leak source can be estimated. Gas samples are simultaneously acquired by filling two or more gas sample storage chambers. This is the default operation mode, which is convenient to regard as recording mode. The other operating mode is a playback mode, where the gas samples in the gas sample storage chamber are sequentially provided to a gas analysis instrument. Gas collection via line pixels can be used to compensate for vertical wind speed variation.
1. A method for performing gas concentration measurements in an ambient, the method comprising:
simultaneously collecting two or more gas samples from two or more measurement locations,
wherein the measurement locations are configured to be on a smooth vertical surface,
wherein the measurement locations are defined by two or more measurement ports that are moved along the smooth vertical surface,
providing the two or more gas samples to a gas analysis instrument to provide gas measurement results; and
providing the gas measurement results as an output;
wherein gas contributions from all of the two or more measurement ports are combined to provide a single input to the gas analysis instrument via a gas flow control manifold;
wherein the measurement ports and the gas flow control manifold are configured to provide equal transit time for all of the gas contributions from their corresponding measurement port to the input to the gas analysis instrument;
wherein the measurement ports are configured to have inlet flow and/or inlet spacing that provide a weighting of contributions according to vertical height.
2. The method of claim 1 , wherein the measurement ports are configured to have equally spaced apertures having equal flow.
3. The method of claim 1 , wherein the weighting increases with vertical height.
4. The method of claim 1 , wherein the weighting is in accordance with a wind speed model.
5. The method of claim 1 , wherein the equal transit time is provided by a tree-like arrangement of gas tubing.
6. The method of claim 1 , further comprising providing a gas flux estimate from the gas measurement results.
7. The method of claim 1 , wherein the measurement ports are configured to have flow rates for the measurement ports that provide an accurate average for estimating gas flux.
8. A system for performing gas concentration measurements in an ambient, the system comprising:
a gas flow control manifold configured to collect two or more gas samples from two or more measurement locations;
wherein the measurement locations are configured to be on a smooth vertical surface,
wherein the measurement locations are defined by two or more measurement ports that are moved along the smooth vertical surface, and
a gas analysis instrument;
wherein gas contributions from all of the two or more measurement ports are combined to provide a single input to the gas analysis instrument via the gas flow control manifold;
wherein the measurement ports and the gas flow control manifold are configured to provide equal transit time for all of the gas contributions from their corresponding measurement port to the input to the gas analysis instrument;
wherein the measurement ports are configured to have inlet flow and/or inlet spacing that provide a weighting of contributions according to vertical height.
9. The system of claim 8 , further comprising a mast configured to be affixed to a vehicle, wherein the measurement ports are disposed on the mast.
10. The system of claim 9 , further comprising a global positioning system (GPS) receiver to track horizontal position of the vehicle.
11. The system of claim 9 , further comprising a vehicle speed sensor and a subsystem for converting time and vehicle speed information to position information.
12. The system of claim 8 , wherein the measurement ports are configured to have equally spaced apertures having equal flow.
13. The system of claim 8 , wherein the weighting increases with vertical height.
14. The system of claim 8 , wherein the weighting is in accordance with a wind speed model.
15. The system of claim 8 , wherein the inlet flow of the contributions can be altered in operation.
16. The system of claim 8 , wherein the equal transit time is provided by a tree-like arrangement of gas tubing.