Abstract: A probe body (12) in a optical probe (10) including a measurement tube (14) having a plurality of probe vents (16) adapted to allow process fluid to flow there through; two or more purge rings, each including a process window, a purge gas inlet, and a plurality of purge gas outlet openings adapted to direct purge gas toward or adjacent to the process window; and a measurement region defined by a portion of the measurement tube and two or more of the purge rings.

Abstract: Apparatus for spectroscopic analysis which includes a tunable diode laser spectrometer having a digital output signal and a digital computer for receiving the digital output signal from the spectrometer, the digital computer programmed to process the digital output signal using a multivariate regression algorithm. In addition, a spectroscopic method of analysis using such apparatus. Finally, a method for controlling an ethylene cracker hydrogenator.

Abstract: A method for control of the air/fuel ratio of the burner(s) (excess air) of a thermal cracker includes three steps. The thermal cracker has three consecutive zones or portions through which combustion gases pass, a firebox portion, a bridge wall portion and a convection portion The first step is to direct a wavelength modulated beam of near infrared light from two different tunable diode lasers located in the bridge wall portion through combustion gas from the burner to a pair of near infrared light detectors, each positioned to receive the wavelength modulated beam of near infrared light from a different one of the two tunable diode lasers to generate a detector signal. The second step is to analyze the detector signals for spectroscopic absorption at wavelengths characteristic of oxygen and carbon monoxide to determine their respective concentrations in the combustion gas.

Abstract: A method for control of the air/fuel ratio of the burner(s) (excess air) of a thermal cracker includes three steps. The thermal cracker has three consecutive zones or portions through which combustion gases pass, a firebox portion, a bridge wall portion and a convection portion The first step is to direct a wavelength modulated beam of near infrared light from two different tunable diode lasers located in the bridge wall portion through combustion gas from the burner to a pair of near infrared light detectors, each positioned to receive the wavelength modulated beam of near infrared light from a different one of the two tunable diode lasers to generate a detector signal. The second step is to analyze the detector signals for spectroscopic absorption at wavelengths characteristic of oxygen and carbon monoxide to determine their respective concentrations in the combustion gas.

Abstract: A method for control of the air/fuel ratio of the burner(s) (excess air) of a thermal cracker which includes three steps. The first step is to direct a wavelength modulated beam of near infrared light from a tunable diode laser through combustion gas from the burner to a near infrared light detector to generate a detector signal. The second step is to analyze the detector signal for spectroscopic absorption at wavelengths characteristic for an analyte selected from the group consisting of oxygen, carbon monoxide and nitrogen oxide to determine the concentration of the analyte in the combustion gas. The third step is to adjust the air/fuel ratio of the burner(s) (excess air) in response to the concentration of the analyte of the second step.

Abstract: The invention pertains to a method for controlling the Limiting Oxygen Value (LOV) of a reactor for producing ethylene oxide using a tunable diode laser. The sample to be tested is extracted. A method for controlling oxygen analyzer safety shutdown for a reactor for producing ethylene oxide using a tunable diode laser is also described.

Abstract: The invention pertains to a method for controlling the Limiting Oxygen Value (LOV) of a reactor for producing ethylene oxide using a tunable diode laser. The sample to be tested is extracted. A method for controlling oxygen analyzer safety shutdown for a reactor for producing ethylene oxide using a tunable diode laser is also described.

Abstract: Apparatus for spectroscopic analysis which includes a tunable diode laser spectrometer having a digital output signal and a digital computer for receiving the digital output signal from the spectrometer, the digital computer programmed to process the digital output signal using a multivariate regression algorithm. In addition, a spectroscopic method of analysis using such apparatus. Finally, a method for controlling an ethylene cracker hydrogenator.

Abstract: A medical breath component analyzer which maintains a data-base profile of a patient over time. The apparatus may be used chronically by a patient so that a baseline status for that patient may be determined. Acute variations from the baseline are identified as clinically significant. The acquired data can be reported to the patient using the device at home and transmitted electronically to a physician or health care provider. The method and apparatus helps a patient modify health related behaviors, particularly weight loss for diabetic patients. A breath component and information on the psychological or emotional state of the patient are correlated, and information is provided to the patient based on the correlation between the breath component and the patient's emotional state. Other physiologic parameter may also be measured, such as a blood component, temperature, cardiovascular condition or pulse rate, a urine component, a physical activity sensor, weight, or body fat composition sensor.

Abstract: A medical breath component analyzer which maintains a data-base profile of a patient over time. The apparatus may be used chronically by a patient so that a baseline status for that patient may be determined. Acute variations from the baseline are identified as clinically significant. The acquired data can be reported to the patient using the device at home and transmitted electronically to a physician or health care provider. The method and apparatus helps a patient modify health related behaviors, particularly weight loss for diabetic patients. A breath component and information on the psychological or emotional state of the patient are correlated, and information is provided to the patient based on the correlation between the breath component and the patient's emotional state. Other physiologic parameter may also be measured, such as a blood component, temperature, cardiovascular condition or pulse rate, a urine component, a physical activity sensor, weight, or body fat composition sensor.

Abstract: A medical breath component analyzer which maintains a data-base profile of a patient over time. The apparatus may be used chronically by a patient so that a baseline status for that patient may be determined. Acute variations from the baseline are identified as clinically significant. The acquired data can be reported to the patient using the device at home and transmitted electronically to a physician or health care provider. Multiple tests may be provided, ranging from quantitative tests to qualitative tests to quantitative approximations using qualitative devices. A set of tests is selected for a particular patient, and may be customized to the patient's condition. One of the tests may include passing multiple laser beams of differing wavelengths through a breath sample and using pattern recognition to correlate from spectral analysis of all the laser beams.