Apparatus for analyzing fluid by multi-fluid modulation mode

A fluid analyzer for use in a simultaneous and continuous measurement of three ingredients, including a first ingredient and a second ingredient being ingredients of the same stock contained in a sample fluid, and also a third ingredient defined as the sum total of said first and second ingredients, said measurement being according to a differential method in which a third concentration of said third ingredient and a first concentration of said first ingredient are directly measured by means of detectors of the same kind and a second concentration of said second ingredient is indirectly measured from a difference between said third and first concentrations, comprising:

• two passage means for dividing said sample fluid into a first sample fluid and a second sample fluid flowing through the two passages, the passage of said first sample fluid being provided with a converter for one of removing the second ingredient from the first sample fluid, and converting the second ingredient to the first ingredient therein to serve as one of a line for use in the measurement of the first concentration of the first ingredient and a line for use in the measurement of the concentration of the third ingredient, the passage of said second sample fluid being provided without a converter to serve as one of a line for use in the measurement of the concentration of the third ingredient (total concentration) and a line for use in the measurement of the first concentration of the first ingredient;
• fluid modulation means for subjecting said converted first sample fluid and said unconverted second sample fluid to a fluid modulation by a reference fluid at two frequencies different from each other, said fluid modulation means being provided in both passages;
• an analyzer provided with only one detector capable of detecting both the concentration of said first ingredient and the concentration of said third ingredient and providing an output signal;
• and
• means for processing the output signal from said detector to divide it into signal components respectively having one of the two modulation frequencies of said first and second sample fluids followed by rectifying and levelling to separately measure said concentration of the first ingredient and said concentration of the third ingredient, whereby said concentration of the second ingredient is able to be measured from the difference between the results of the measurement of the first and third concentrations.

A gas analyzer, comprising:

• two cells having different cell-lengths and disposed between a light source and a detector in series;
• two fluid modulation means for simultaneously and continuously supplying said respective cells with a sample gas and a reference gas at an appointed period in a changed-over manner, one of said fluid modulation means being provided for each respective cell, modulation frequencies of the sample gas and the reference gas by the two modulation means being adapted to be different from each other;
• and
• means for measuring a concentration of an ingredient to be measured in the sample gas to enable the ingredient to be measured over a lower concentration to a higher concentration range by dividing an output from said detector into signal components respectively having the modulation frequencies of said sample gas and said reference gas for said respective cells which is followed by rectifying and levelling the signal components.

A gas analyzer, comprising:

• two cells being disposed in parallel to each other and between a light source and a detector;
• a filter having an absorption band at a wavelength which is almost the same as a characteristic absorption wavelength of an ingredient to be measured, said filter being disposed in an optical path on a side of one cell;
• two fluid modulation means for simultaneously and continuously supplying said respective cells with a sample gas and a reference gas at an appointed period in a changed-over manner, one of said fluid modulation means being provided for each respective cell, modulation frequencies of the sample gas and the reference gas by the two modulation means being adapted to be different from each other;
• and
• means for measuring a concentration of an ingredient to be measured in the sample gas by dividing an output signal from said detector into separate signal components respectively having the modulation frequencies of said sample gas and said reference gas for said respective cells which is followed by rectifying, levelling and taking a difference between the signal components.

A two-ingredient measurement-type gas analyzer, comprising:

• two cells being disposed in parallel between a light source and a detector;
• a filter, having an absorption band at a wavelength which is almost the same as a characteristic absorption wavelength of an ingredient to be measured, being provided for each respective cell;
• a pair of fluid modulation means for simultaneously and continuously supplying said respective cells with a sample gas and a reference gas at an appointed period in a changed-over manner for said respective cells, modulation frequencies of the sample gas and the reference gas by these two modulation means being adapted to be different from each other;
• and
• means for processing an output signal from said detector so as to divide the output signal into signal components respectively having the modulation frequencies of said sample gas and said reference gas for said respective cells which is followed by rectifying and levelling the signal components to obtain a measurement of each respective ingredient.

Apparatus for analyzing components of sample fluids, divided into a plurality of sample portions, comprising:

• sensor means for providing an output signal indicative of a component to be measured in a sample fluid;
• means for modulating sample portions to provide at least two different modulation frequencies at the same time, each frequency being characteristic of a specific sample portion delivered to the sensor means;
• means for mixing the sample portions and simultaneously supplying the mixed sample portions to the sensor means;
• and
• means for processing the output signal relative to the modulation frequencies to correlate a portion of the output signal with the appropriate modulated sample portions to enable a determination of the component within each sample portion.