JP3500139B2 - Composition measuring device using laser - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring composition components using a laser, and measures the calorific value, unburned content, and composition components of pulverized coal, fly ash and cement raw materials. It is suitable for application. [0002] In order to measure the calorific value, unburned content, and composition of pulverized coal, fly ash and cement raw materials, a laser-induced breakdown method (Laser Induced Breakdown Spectr) is used.
Oscopy: LIBS method) has been developed. FIG. 5 shows a composition component measuring apparatus adopting the LIBS method which has already been developed. As shown in the figure, an object to be measured is present (distributed) in a pipe 21 of various plants and the like. The measurement object includes pulverized coal, fly ash, cement raw material, and the like. A measurement window 13 having a purge flow path 13a is installed in a portion of the pipe 21 at the measurement site 20. The laser light output from the pulse laser device 11 is focused on the measurement field 20 via the lens 12 and the measurement window 13. For this reason, the measurement site 20
The fine particles (particles of the object to be measured) existing in the plasma are turned into plasma, and plasma light is generated from the plasma-converted composition components. The generated plasma light is output from the measurement window 13 of the measurement field 20 to the outside, is reflected by the mirror 14, is further condensed by the lens 15, and is incident on the spectroscope 16.
The spectroscope 16 spectrally converts the plasma light into spectral light, and inputs the spectral light into the CCD camera 17. [0005] The CCD camera 17 capable of high-speed gate is
The spectrum light separated by the spectroscope 16 is photographed, and a video signal corresponding to the spectrum light is transferred to the computer 18. The CCD camera 17 is connected to the pulse laser device 11 via a synchronous line 19,
The gate control of the camera 17 and the oscillation of the pulse laser device 11 are synchronized. [0006] The computer 18 performs information processing on the transferred video signal (having luminescence intensity information from each component), and thereby processes the pulverized coal, fly ash, and cement raw material existing in the measurement place 20. Calorific value, unburned component,
Calculate composition components and the like in real time. That is, the composition component is identified from the difference in the emission wavelength of the spectrum light as shown in FIG. 6, and the concentration of the composition component is obtained from the emission intensity. For example, in order to detect unburned components contained in exhaust gas discharged from a boiler furnace of a coal-fired thermal power plant, Si, Al, which is a main component in ash, is detected.
The Ca component due to Ca, Fe and unburned components is measured, and S
The unburned portion is calculated from the ratio of i, Al, Ca, Fe and C caused by the unburned portion. Then, based on the calculated unburned portion, the unburned portion can be controlled by changing the combustion conditions in the boiler furnace, such as increasing or decreasing the degree of pulverization of the pulverized coal. As described above, since the composition of the measurement object can be measured in real time at the measurement site, the operation control of the plant or the like can be favorably executed based on the measurement result. [0009] This apparatus is composed of pulverized coal, fly ash,
Not only in the field of measuring the composition of cement raw materials, but also in C, S
The invention can also be applied to the field of measuring the composition of fine particles mainly composed of i, A1, Fe, Ca, Mg, K, Na, and the like. [0010] By the way, when a measurement object is irradiated with laser light, plasma light is generated from each of the composition components which have been turned into plasma. Are different. That is, FIG.
As shown in (1), for a certain composition component A, light emission is started (at timing t1) a short time after the timing (t0) at which the laser light is irradiated, and the light emission start timing t
The light emission is continued from 1 to the light emission time T1, while the other component B is emitted after a long time (timing t0) from the timing (t0) at which the laser light is irradiated.
2) Light emission is started, and light emission is continued from the light emission start timing t2 for the light emission time T2. Other components also have different emission start timings and emission times. By the way, there are Fe, C, and the like as composition components that emit light in a short time after irradiation with laser light, and A1 and the like as composition components that emit light after a long time has elapsed. Accordingly, plasma light having a different emission time is generated from each of the composition components at different times, and the spectrum light obtained by dispersing the plasma light shifted at such a time is as follows.
The light enters the CCD camera 17 with a time lag. For this reason, when the photographing start time and the photographing continuation time of the CCD camera 17 are fixed (fixed), there is a limit in improving the detection accuracy of the composition component. In view of the above prior art, an object of the present invention is to provide a composition component measuring apparatus using a laser capable of improving the measurement accuracy of a composition component of an object to be measured. According to the present invention, there is provided a laser apparatus for irradiating an object to be measured with a laser beam to convert the composition into plasma, and each of the plasma-converted components. Optical system that collects plasma light that is generated with a time lag, multiple optical fibers that transmit the collected plasma light, and each plasma light that is transmitted by multiple optical fibers A spectroscope that splits the spectral light into spectral light and distributes and separates each spectral light to spatially different positions, and a plurality of spectral lights output from the spectrometer are photographed and obtained. A solid-state imaging device camera that outputs a video signal; and a computer that identifies a component of the measurement target and detects the concentration of the component based on the video signal, and the plurality of optical fibers The length of the other optical fiber longer than that of the shortest optical fiber is changed from the timing of the generation of the plasma light from the first generation of the plasma light to the generation of the plasma light after the timing of the generation of the plasma light. It is characterized in that it is longer by a distance obtained by multiplying a transmission speed of light in the optical fiber by a time until a light is generated. Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a composition component measuring apparatus using a laser according to an embodiment of the present invention. As shown in the figure,
An object to be measured is present (distributed) in the piping 121 of various plants and the like. The measurement object includes pulverized coal, fly ash, cement raw material, and the like. A measurement window 113 having a purge flow channel 113a is provided in a portion of the pipe 121 at the measurement site 120. The laser light output from the pulse laser device 111 is focused on the measurement field 120 via the lens 112 and the measurement window 113. Therefore, the fine particles (particles of the object to be measured) existing in the measurement field 120 are turned into plasma, and plasma light is generated from the plasma-converted composition components. The generated plasma light is output from the measurement window 113 of the measurement field 120 to the outside, reflected by the mirror 114, further condensed by the lens 115, and simultaneously incident on the two optical fibers 122 and 123. . Optical fiber 12
2, the optical fiber 123 is longer. Specifically, a distance obtained by multiplying a time T3 (see FIG. 2) between the light emission start timing t1 of the composition component A and the light emission start timing t2 of the composition component B by the transmission speed of light in the optical fibers 122 and 123. However, the optical fiber 123 is longer than the optical fiber 122. FIG. 3 is a sectional view taken along the line III-III in FIG.
It is sectional drawing. The plasma light incident on the optical fibers 122 and 123 is transmitted by the optical fibers 122 and 123 and is incident on the spectroscope 116. The spectroscope 116 separates the plasma light transmitted by the optical fiber 122 and the plasma light transmitted by the optical fiber 123 independently from each other to obtain respective spectrum lights.
Then, the spectrum light is distributed to spatially different positions and output. A CCD camera (solid-state imaging device camera) 117 capable of high-speed gating photographs spectral light output from the spectroscope 116 while being distributed to spatially different positions. FIG. 4 shows the state of the spectrum light captured by the CCD camera 117, α represents the spectrum light obtained by dispersing the plasma light transmitted through the optical fiber 122,
β indicates a spectrum light obtained by dispersing the plasma light transmitted through the optical fiber 123. This CCD camera 117 is
A video signal corresponding to the captured spectrum lights α and β is transferred to the computer 118. The CCD camera 117
Is connected to the pulse laser device 111 via the synchronization line 119.
The gate control of the CCD camera 117 and the oscillation of the pulse laser device 111 are synchronized. The synchronization timing will be described later. The computer 118 performs an information processing operation on the transferred video signal (having emission intensity information from each component), thereby identifying and determining the concentration and concentration of the component components A and B existing in the measurement field 120. Is calculated in real time. Here, the photographing timing of the CCD camera 117 will be described. As shown in FIG. 2, the plasma light of the composition component A is generated first, and then the plasma light of the composition component B is generated. The plasma lights of the composition components A and B are both incident on the optical fibers 122 and 123 and transmitted. Here, when examining the plasma light of the component A, the optical fiber 12
2 transmitted first reaches the spectroscope 116 and becomes spectral light, and of the plasma light of the component A, the one transmitted through the optical fiber 123 subsequently reaches the spectroscope 116 and becomes spectral light. Next, when examining the plasma light of the composition component B, of the plasma light of the composition component B, the one transmitted through the optical fiber 122 first reaches the spectroscope 116 and becomes the spectrum light. The light transmitted through the optical fiber 123 subsequently reaches the spectroscope 116 and becomes spectral light. As described above, the optical fiber 123 emits light relative to the optical fiber 122 at the time T3 (see FIG. 2) between the light emission start timing t1 of the composition component A and the light emission start timing t2 of the composition component B. It is longer by a distance multiplied by the transmission speed of light in the fibers 122 and 123. As a result, of the plasma light of the composition component A that emits light first, the longer optical fiber 123 is transmitted, and the plasma light of the composition component B that emits light later is transmitted through the shorter optical fiber 122. What was sent at the same time
6 and are respectively separated into spectral lights β and α. The CCD camera 117 transmits the longer one of the plasma light of the composition component A, which is emitted first, through the optical fiber 123, and the shorter one of the plasma light of the composition component B, which is emitted later. The light transmitted through the fiber 122 simultaneously reaches the spectroscope 116 and starts photographing at the timing when the spectral lights β and α which are separated are output from the spectroscope 116, and is fixed from this photographing start timing. Shoot time. The spectral lights β and α photographed at this time are obtained by dispersing light when the emission intensity of the plasma light generated from the composition components A and B increases. By setting the photographing timing of the CCD camera in this way, the spectral lights β and α obtained by spectrally dispersing the plasma light generated from the composition components A and B when the emission intensity is large by one photographing operation are obtained. You can shoot at the same time. For this reason, the measurement accuracy of the composition component of the measurement object can be improved. When detecting three or more kinds of composition components having different light emission timings, three or more optical fibers are used, and the three or more optical fibers are longer than the shortest optical fiber. The length of the optical fiber in the optical fiber is the time from the timing when the plasma light is generated from the first component generating plasma light to the timing when the plasma light is generated from the component generating plasma light thereafter. Is adjusted to be longer by the distance multiplied by the transmission speed of the light. With this configuration, it is possible to simultaneously photograph three or more types of spectrum light obtained by spectrally separating the plasma light when the emission intensity generated from the three or more types of composition components is large, and to obtain the composition components of the measurement object. Measurement accuracy can be improved. As described above in detail with the embodiments, according to the present invention, there are provided a laser device for irradiating a measurement object with a laser beam to convert its composition into plasma, An optical system for condensing plasma light generated with a time lag from the composition component, a plurality of optical fibers for transmitting the condensed plasma light, and each plasma light transmitted by the plurality of optical fibers. A spectroscope that separates and separates each spectrum light into spectral light, distributes each spectral light to spatially different positions and outputs, and a plurality of spectral lights output from the spectrometer and shoots. A solid-state imaging device camera that outputs the obtained video signal; and a computer that identifies a component of the measurement target and detects the concentration of the component based on the video signal, and The length of the fiber is longer than that of the shortest optical fiber, and the length of the other optical fiber is longer than that of the plasma component that generates plasma light from the first component that generates plasma light. Since the time until the timing when the plasma light is generated is longer by the distance multiplied by the transmission speed of the light in the optical fiber, the plasma light when the emission intensity generated from a plurality of types of composition components is large is separated. It is possible to photograph a plurality of spectrum lights obtained at the same time, and it is possible to improve the measurement accuracy of the composition components of the measurement object.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram showing a composition component measuring device using a laser according to an embodiment of the present invention. FIG. 2 is a characteristic diagram showing a plasma generation timing of each composition component. FIG. 3 is a sectional view taken along the line III-III of FIG. 1; FIG. 4 is a characteristic diagram showing a state of spectrum light captured by a CCD camera. FIG. 5 is a configuration diagram showing a conventional composition component measuring device using a laser. FIG. 6 is a characteristic diagram showing a plasma emission spectrum of pulverized coal. [Description of Signs] 11,111 Pulse laser device 12,112 Lens 13,113 Measurement window 14,114 Mirror 15,115 Lens 16,116 Spectroscope 17,117 CCD camera 18,118 Computer 19,119 Synchronization line 20,120 Measurement sites 21, 121 Piping 122, 123 Optical fiber

Continued on the front page (58) Fields investigated (Int.Cl. ⁷ , DB name) G01N 21/62-21/74 Practical file (PATOLIS) Patent file (PATOLIS)

Claims (1)

(57) [Claims 1] A laser device for irradiating a measurement object with a laser beam to convert its constituent components into plasma, and a plasma generated with a time lag from each of the plasmated constituent components An optical system for condensing the light, a plurality of optical fibers for transmitting the condensed plasma light, and each plasma light transmitted by the plurality of optical fibers being independently separated into spectrum light and , A spectroscope that divides and outputs each spectral light that has been separated into spatially different positions, and a solid-state imaging device camera that photographs a plurality of spectral lights output from the spectroscope and outputs a video signal obtained by photographing. And, having a computer that identifies the composition of the measurement object and detects the concentration of the composition based on the video signal, wherein the plurality of optical fibers are shorter than the shortest optical fiber. The length of the other long optical fiber is the time from the timing when the plasma light is generated from the composition component that first generates the plasma light to the timing when the plasma light is generated from the composition component that generates the plasma light thereafter. A composition component measuring apparatus using a laser, wherein the length is increased by a distance multiplied by a transmission speed of light in an optical fiber.