Article Archive
Detecting Fugitive Vapors
Detector checks floating roof tanks for escaping fumes and seal fires
Volume 23. No 4

In mid-year 2007, Delacom was approached to develop a solution to monitor floating roof petroleum storage tanks in order to 1) detect fugitive vapors before they could cause an explosion and 2) detect incipient fires caused by lightning around the seal that could not be observed from the ground. The product developed has the ability to detect most explosive, hazardous, toxic or environmentally sensitive vapors and the ability to be integrated into a comprehensive system providing detection of vapor, smoke, fire and intrusion.

The Technology

The DDS optical detection system is a software centric product, transparent to the camera type or model that continuously monitors an area and automatically provides an audible and visual alarm in the control center when fugitive emissions are detected.?? Detection targets are not limited to hydrocarbons and can be applied to detect any vapor that has a light absorption wavelength in Ultraviolet, Visible, or IR spectrum with the capability to segregate and focus on specific vapors.

The base system was commercially deployed to detect smoke and fire in harbors, large industrial sites and forests.? Delacom directed the development of fugitive vapor detection, successfully tested the system with consumer grade, industrial visible range and industrial IR cameras and acquired patent protection.

Contributing factors that make this system a powerful tool are:

  • It analyzes and evaluates the image rather than attempting to match the image to an existing library as in image recognition software.
  • It reduces the image to its mathematical components providing the system with the capability to identify each small component, edge and movement within the image."
  • The use of Hidden Markov Models, a system used in voice recognition, and the ability to provide pre-guidance for the Hidden Markov Models permits flexibility in changing?conditions and focus on specific compounds.

Automatic detection is annunciated by an audible alarm and a visual location indicator at the control station.? System capability includes recording, search and retrieval functions with the recording option selectable as continuous or only on event. Communication between the sensor and the control station can be wired or wireless and the control station can be local, remote or both.

Applications

Two applications demonstrate the flexibility and breadth of the Delacom system.

CANADIAN? ENERGY? COMPANY

The company has asked for alternative methods for detecting methane and other vapors.? Specifically, they are seeking improvements in:

  • Vapor leak detection and location;
  • Reduction in the level of training and? experience required;
  • Reduction in the? level of false alarms;
  • Detection of H2S and differentiation from methane.

In order to customize the algorithms and hardware, a profile of the compound in a vapor state is created.? After analysis, it was determined to maximize the detection capability. The system will monitor both the 3.5 and 7.5 micron wavelengths. The optical sensor will be selected with a spectral capability range of three to eight microns minimum (DDS has identified this model and availability in the market). The software algorithms will be customized to maximize the detection capability at the methane wavelength points, differentiate at H2S wavelengths and filter those wavelengths outside the target points.

CZECH? REPUBLIC? ENERGY? COMPANY

The company has a history of fatalities due to the leakage of hydrogen sulfide. The company is seeking a system that will:

  • Identify the leak;
  • Identify the general location of the leak;
  • Provide for detection and differentiation of both ammonia and hydrogen sulfide;
  • Allow man portable units to be deployed during the repair and retest of the system.

Determination of the compound characteristics in vapor mode is required. Ammonia has a frequency absorption wavelength centered at 10.5 microns and hydrogen sulfide at eight microns. Both compounds are within the spectral range of an LWIR camera. Both of these compounds are heavier than air affecting the positioning and scanning area of the cameras.

An LWIR camera with specific servo mounts will be utilized in the detec-tion process. Anal-ysis and pre-guidance of the vapor cha-racteristics will allow the sys-tem to en-hance the va-por detection.? Two virtual programs will be created at the control ce-nter, one for each compound. The programs will run? parallel and the video image will be fed to each simultaneously. When an alarm occurs, the system will identify which virtual program generated the alarm and which compound was detected as leaking.

In order to maximize the effectiveness of the sensors and detect the location of the leak, the sensors are mounted on pan and tilt servo systems.?? These systems, installed with position feedback devices, will identify the azimuth and elevation of the sensor at the time of the detection. Set up of the system will include a digital map of the area being monitored. The elevation and azimuth information will be over-layed on the map identifying the location.

This application requires multiple sensors to monitor the required area. The system, as currently config-ured, can accept input from eight sensors. For locat-ion, the system will identify vapor, cam-era, area, azimuth and elevation location.

Once a leak is identified and the general area located, a repair team will be dispatched to clear the area of the toxic gas and repair the leak. The repair team will utilize a DDS mobile unit for ongoing monitoring and retesting.

Summary

DDS Optical Detection Systems can monitor fugitive emissions on a permanent or mobile basis and send detection visual and audible alarm signals to either local or remote locations.???

The system is:

  • Commercially-proven process adapted to vapor detection;
  • Independent of optical sensor and can detect vapors that ?have light absorption frequencies from Ultra Violet to Infrared
  • Independent of camera type;
  • Can be supplied in a fixed or mobile configuration;
  • Single or multiple detection of vapor, smoke, flames or intrusion.

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