On-line measurement of lignin in wood pulp by color shift of fluorescence
AssigneeThe Babcock & Wilcox Company
InventorsLarry A. Jeffers, Michael L. Malito
Life of this patent
Estimating the term…
Abstract
Lignin concentrations from wood pulp samples are measured by applying an excitation light at a selected wavelength to the samples in order to cause the lignin to emit fluorescence. A spectral distribution of the fluorescence emission is then determined. The lignin concentration is then calculated based on the spectral distribution signal. The spectral distribution is quantified by either a wavelength centroid method or a band ratio method.
Claims23
An apparatus employing a color shift of fluorescence for measuring lignin concentration in at least one undiluted sample on a real-time, in-situ basis based upon a spectral distribution of fluorescent emission light from the sample, comprising:
- light source means for applying excitation light at a selected wavelength to the at least one undiluted sample for causing the sample to produce fluorescent emission light having a spectral distribution of fluorescent intensity;
- light detector means for detecting the fluorescent intensity of the emission light and determining the spectral distribution of fluorescent intensity and establishing signals indicative thereof;
- signal processing means operatively connected to the light detector means for calculating a lignin concentration from the spectral distribution signals and producing a signal indicative thereof;
- and
- means for displaying the signal indicative of the calculated lignin concentration for viewing by an operator.
A system for controlling a delignification process which employs a color shift of fluorescence to measure lignin concentration in at least one undiluted lignin sample in the process on a real-time, in-situ basis to produce a signal indicative of lignin concentration in the sample based upon a spectral distribution of fluorescent emission light from the sample, comprising:
- light source means for applying excitation light at a selected wavelength to the at least one undiluted sample for causing the sample to produce fluorescent emission light having a spectral distribution of fluorescent intensity;
- light detector means for detecting the fluorescent intensity of the emission light and determining the spectral distribution of fluorescent intensity and establishing signals indicative thereof;
- signal processing means operatively connected to the light detector means for calculating lignin concentration from the spectral distribution signals and producing a signal indicative thereof;
- and
- process control elements, connected to the signal processing means, for controlling the delignification process in response to the lignin concentration signal.
A method for controlling a delignification process which employs a color shift of fluorescence to measure lignin concentration in at least one undiluted sample in the process on a real-time, in-situ basis to produce a signal indicative of lignin concentration in the sample based upon a spectral distribution of fluorescent emission light from the sample, the method comprising the steps of:
- applying an excitation light at a selected wavelength to the at least one undiluted sample to cause the sample to emit fluorescent emission light;
- determining a spectral distribution of the fluorescent emission light and establishing signals indicative thereof;
- calculating the lignin concentration from the spectral distribution signals;
- and
- controlling the delignification process by providing the signal indicative of the calculated lignin concentration to process control elements associated with the delignification process and responsive to said lignin concentration signal.
Dependencies are inferred from the claim text.