US 4,069,018 A · Explosive gas monitoring method and apparatus

Abstract

Monitoring of the recirculated atmosphere of an oxygen pulping reactor to determine when the inflammability level of combustible gases in the reactor atmosphere has reached a predetermined percentage of the lower explosive limit (LEL) of the reactor atmosphere in terms of combustible organic vapors and carbon monoxide is disclosed. Continuous or discrete samples of the reactor atmosphere are taken at spaced regions, and the samples are applied to: (1) flame ionization detectors, which determine the concentration of combustible organic vapors (e.g., aliphatic, olefinic, aromatic, acetylenic, alcohols, aldehydes, ketones, etc.) in the samples; and, (2) carbon monoxide analyzers, which determine the concentration of carbon monoxide in the samples. The outputs of the flame ionization detectors are calibrated in terms of percent LEL for the contributing combustible organic vapors and, thus, provide percent combustible organic vapor LEL information. The outputs of the carbon monoxide analyzers are calibrated in terms of percent LEL based on the carbon monoxide in the samples. The outputs of the flame ionization detectors are compared and the highest percent output is applied to an alarm and recording subsystem. These outputs are also compared to determine if they are close to one another. If the comparison indicates that a substantial difference exists, a differential sensor activates a further alarm to denote a wide variance that may indicate a faulty detector channel. Similarly, the outputs of the two carbon monoxide analyzers are compared and the highest percent output is applied to an alarm and recording subsystem. Also, if the outputs are substantially different a differential indicator is activated. In addition, in an alternate embodiment, the highest flame ionization output is summed with the highest carbon monoxide analyzer output and the result applied to a controller that continuously controls the position of a vent valve, as well as to an alarm and recording subsystem. Finally, an oxygen analyzer is provided for measuring the oxygen concentration of at least one of the reactor atmosphere samples.

Claims32

Dependent claims

A method of monitoring an atmosphere containing combustibles to provide an indication of the inflammability potential of the atmosphere in terms of LEL based on the level of combustibles in the atmosphere being monitored, said method comprising the steps of:

sampling the atmosphere to obtain samples thereof;
determining the combustible organic vapors content of the samples in terms of percent LEL based on the total carbon atom concentration of combustible organic vapors present in the samples;
determining if the combustible organic vapors content of the samples is above a predetermined percent LEL;
providing an indication when the combustible organic vapors content is above said predetermined percent LEL;
determining the carbon monoxide content of the samples in terms of percent LEL based on carbon monoxide present in the samples;
determining if the carbon monoxide content of the samples is above a predetermined percent LEL;
and
providing an indication when the carbon monoxide content is above said predetermined percent LEL.

5 more elements

sampling the atmosphere at at least two different points;
determining the combustible organic vapors content of the samples in terms of percent LEL based on the total carbon atom concentration of combustible organic vapors present in the samples;
determining whether or not the combustible organic vapors content of any of the samples is above a predetermined percent LEL;
providing an indication when the combustible organic vapors content of any of the samples is above said predetermined percent LEL;
determining the carbon monoxide content of the samples in terms of percent LEL based on the carbon monoxide present in the samples;
determining whether or not the carbon monoxide content of any of the samples is above a predetermined percent LEL;
and,
providing an indication when the carbon monoxide content of any of the samples is above said predetermined percent LEL.

5 more elements

sampling the atmosphere at at least two different points;
determining the combustible organic vapors content of the samples in terms of percent LEL based on the total carbon atom concentration of combustible organic vapors present in the samples;
determining the carbon monoxide content of the samples in terms of percent LEL based on the carbon monoxide present in the samples;
combining the combustible organic vapors content in terms of percent LEL with the carbon monoxide content in terms of percent LEL to derive a total combustibles content in terms of percent LEL;
and,
providing an indication of the total combustibles content of the samples.

3 more elements

Apparatus for monitoring a potentially inflammable atmosphere containing combustibles to provide an indication of the inflammability of the atmosphere in terms of LEL based on the level of combustibles in the atmosphere, said apparatus comprising:

sampling means for sampling said atmosphere to obtain samples of said atmosphere;
combustible organic vapors analyzing means connected to said sampling means for determining the combustible organic vapors content of said samples in terms of LEL based on the total carbon atom concentraction of combustible organic vapors present in the samples;
combustible organic vapors indicating means connected to said combustible organic vapors analyzing means for providing an indication when said percent LEL based on the total carbon atom concentration of combustible organic vapors present in the samples;
carbon monoxide content analyzing means connected to said sampling means for determining the carbon monoxide content of said samples in terms of percent LEL based on the carbon monoxide present in the samples;
and, and,
carbon monoxide indicating means connected to said carbon monoxide content analyzing means for providing an indication when said percent LEL based on the carbon monoxide present in the samples is above a predetermined percent LEL.

3 more elements

sampling means for sampling said atmosphere to obtain samples of said atmosphere;
combustible organic vapors analyzing means connected to said sampling means for determining the combustible organic vapors content of said samples in terms of LEL based on the total carbon atom concentration of combustible organic vapors present in the samples;
carbon monoxide content analyzing means connected to said sampling means for determining the carbon monoxide content of said samples in terms of percent LEL based on the carbon monoxide present in the samples;
combining means connected to said combustible organic vapors analyzing means and said carbon monoxide content analyzing means for combining said combustible organic vapors content with said carbon monoxide content to provide a total combustibles content in terms of percent LEL based on the total carbon atom concentration of combustible organic vapors and the carbon monoxide present in the samples;
and,
total combustibles indicating means connected to said combining means for providing an indication of the total combustible content of said samples.

3 more elements

Dependencies are inferred from the claim text.

Explosive gas monitoring method and apparatus

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Explosive gas monitoring method and apparatus

Life of this patent

Abstract

Claims32