초록 ▼

A fiber optics based optical emission line monitoring system is provided in which selected spectral emission lines, such as the sodium emission line, may be detected in the presence of interfering background radiation. A combustion flame is fed by a diverted portion of a process stream and the commo

A fiber optics based optical emission line monitoring system is provided in which selected spectral emission lines, such as the sodium emission line, may be detected in the presence of interfering background radiation. A combustion flame is fed by a diverted portion of a process stream and the common end of a bifurcated or quadfurcated fiber optic light guide is adapted to collect light from the flame. The light is guided through the branches of the fiber optic cable to bandpass filters, one of which is adapted to each of the branches of the fiber optic light guide. The bandpass filters are centered at wavelengths corresponding to the emission lines to be detected and two separate filters are required for each species being detected. The first filter has a bandwidth of about 3 nms and the second filter has a bandwidth of about 10 nms. Light detectors are located to view the light passing through the bandpass filters and amplifiers are connected to receive signals from the light detectors. The amplifier corresponding to the bandpass filter having the narrower bandwidth is preset to scale the signal by a factor equal to the ratio of the wide and narrow bandwidths of the bandpass filters. This scaling produces a scaled signal from which the difference between the scaled signal on the other signal can be calculated to produce a signal having an amplitude directly proportional to the concentration of the species of interest and independent of background radiation.

대표청구항 ▼

A real-time alkali monitoring system for detecting selected alkali emissions from a light source in the presence of interfering background radiation, comprising: a bifurcated fiber optic cable having first and second branches attached to a common trunk and adapted at the common end to optically coup

A real-time alkali monitoring system for detecting selected alkali emissions from a light source in the presence of interfering background radiation, comprising: a bifurcated fiber optic cable having first and second branches attached to a common trunk and adapted at the common end to optically couple light from a light source to said cable; a first bandpass optical filter having a passband centered about a selected emission line and a bandwidth at least as wide as the selected emission line and being disposed to intercept light passing from the end of said first branch of said cable; a second bandpass optical filter having a passband centered about a wavelength identical to that of said first bandpass filter and a bandwidth substantially wider than the bandwidth of said first bandpass filter and being disposed to intercept light passing from the end of said second branch of said cable; a first light detector means for generating a first signal having an amplitude proportional to the intensity of light transmitted through said first bandpass filter, a second light detector means for generating a second signal having an amplitude proportional to the intensity of light transmitted through said second bandpass filter; a means for scaling one of the output signals from said detectors; and, a means for calculating the difference between said scaled output signal and said other output signal to generate a third output signal having an amplitude proportional to the intensity of said emission line being monitored.