TECHNICAL DESCRIPTION SPECTRAFLOW ON LINE ANALYZER for BELT CONVEYOR APPLICATION

Transcription

1 TECHNICAL DESCRIPTION SPECTRAFLOW ON LINE ANALYZER for BELT CONVEYOR APPLICATION

2 TECHNICAL SPECIFICATION SPECTRAFLOW ON LINE ANALYZER FOR BELT CONVEYOR CONTENTS 1. SpectraFlow Technical Description SOLBAS TM Technology SpectraFlow Illumination Head SpectraFlow / SOLBAS Calibration Model Control Industrial PC (IPC) and Interfacing SpectraFlow Scope of Supply Supply needed from others SpectraFlow Analyzer Guarantees and their Verification... 9 Page 2 of 9

3 1. SpectraFlow Technical Description SpectraFlow uses Near Infra Red (NIR) to analyze the bulk minerals on line. The system consists of two major components, the illumination head including the spectrometer and the electrical cabinet, which contains an Industrial PC, which controls the analyzer and does the evaluation of the spectra. 2. Near Infra Red (NIR) Technology NIR is a known technology that has proven to be effective and that it meets all the analysis requirements throughout all minerals industry manufacturing processes. NIR technology utilizes the full wide range of spectra in the near infra red range, which are provided by stabilized white light sources (lamps). Their emitted Near Infra Red radiation hits the target bulk material to be analyzed as it passes by underneath the system on an existing conveyor belt. This NIR radiation excites vibrational oscillations of the molecular bonds in the monitored material, which results in reflection and absorption spectra that are characteristic for the analyzed minerals or constituents. Figure 1: Wide range infrared spectrum measured by NIR Figure 1 above shows a typical set of absorbance spectra, which are received from limestone, which is used as cement raw material. Page 3 of 9

4 3. SpectraFlow Illumination Head The complete NIR spectrum, which is needed to perform the On Line chemical analysis, is supplied by a set of white light sources. These lights do not only emit the visible white light but also NIR radiation, which is used for the analysis. In order to avoid mirror reflection of the Infrared Radiation the sources are arranged off center of the bulk material and send the light onto the material with a settable angle. The light sources have parabolic mirrors in order to get as parallel Infrared Beams as possible to the material. The infrared light reflected by the moving bulk material gets collected by an FTIR (Fourier Transform Infra Red) Spectrometer in the centre of the illumination system. FTIR Spectrometer Light and dust shield 8 lamps in a circle 50 Watt each Bulk Material Figure 2: Basic Principle of the SpectraFlow illumination system The lamps are rated 50 Watts each and have a lifetime of approximately 3000 hours. The lamps are supplied by a stabilized DC Power supply, which has extremely low ripple. Together with the protective shield the close to ideal DC current significantly contributes to noise reduction of the received NIR Spectra Figure 3 shows the top view and a bottom view of the illumination system Page 4 of 9

5 Spectrometer Rails for the illumination lamps Figure 3: Bottom view (left) and top view (right) of the illumination system The opening lid permits to change lights while the belt is moving. The rails inside the illumination head permit to define the optimum position of the lights depending on the height of the system above the belt conveyor. The lamps are in a holder which permits to vary the angle of the light with respect to the vertical axis. This is an additional means to optimize the Infra Red radiation to the bulk material. Figure 4 shows what a single light holder looks like Lamp (NIR Source) Figure 4: Lamp holder In case the lamp needs to be changed the cap can be screwed off the lamp holder, which permits access to the lamp. The lamp has a plug which makes the electric contact. It is pulled out towards the front of the lamp holder in case it needs to be replaced. The Spectrometer entry can either be a flat glass or a lens. The final decision depends on the distance from the belt conveyor. In normal raw material applications a flat glass is sufficient. If however the plant conditions require a very short distance between the illumination head and the belt conveyor a lens may become necessary in order to straighten the incoming Page 5 of 9

6 beams i.e. to improve the parallelism of the beam that enters the FTIR spectrometer. An FTIR spectrometer is used to generate the absorbance spectra output because it defines each single spectrum in one step. This means it is extremely stable and calibration models can be easily transferred from one spectrometer to the other. The FTIR spectrometer can utilize much more of the reflected NIR radiation than a standard dispersive NIR Spectrometer and it is mechanically extremely robust. Standard dispersive spectrometers use typically an electric micromotor inside, in order to achieve the split up of the received NIR beam. The FTIR spectrometer does not need any electric motor. A periodically excited electromagnet is sufficient. All these features ascertain an extremely stable measurement performance. The system does not need a frequent alignment to an external reference 1. SFA recommends to perform an external white reference taking twice a year once at winter time and once in summer time to account for the different ambient conditions during these periods. 4. SpectraFlow Calibration Model An Online Analyzer irrespective, which type of radiation it uses to get information about the chemical composition of the analyzed bulk material needs a calibration model, which performs the transformation of the received spectra into chemical concentrations. The SpectraFlow systems are delivered with a customized calibration models for the appropriate application. To build the initial calibration model well analyzed samples have to be provided to SFA approximately 4 weeks before the intended shipping date. Depending on the application and the ranges for the different components 20 to 50 samples are needed. The samples should cover the range for each component that should be analyzed. SFA requires approximately kg of well analyzed sample material. After the installation of the SpectraFlow system the on-line results are compared with the laboratory XRF results and the calibration model is optimized for the specific customer ranges. This will improve the accuracy of the reported analyzed components regarding the XRF. Page 6 of 9

7 Figure 5: Example for a Calibration Model for CaO The installation of the SpectraFlow system is quick and easy. The client installs an adjustable frame over the conveyor belt that supports the illumination system. A separate support is needed for the electronics cabinet containing the stabilized power supply for the lamps, the communication electronics and an industrial PC, which does the control of the system and the evaluation of the concentrations. Total weight of all components is approximately 180 kg. The SpectraFlow illumination head does not need to be installed perpendicular to the conveyor belt. It can be installed on any angle over the belt. Page 7 of 9

8 FTIR Spectrometer Position Illumination Head with the lamps as Infra Red Source Figure 6: Example of the structure for the analyzer For weather protection in an outdoor installation, the analyzer shall be enclosed all around to avoid stray light. Figure 7 shows an installed analyzer above a belt conveyor FTIR Spectrometer Position Control Panel Illumination Head Figure 7: Picture of an installed belt conveyor analyzer Page 8 of 9

9 5. Control Industrial PC (IPC) and Interfacing Inside the control panel is a dual core Industrial PC (IPC). On one core runs a Soft PLC, which controls and supervises the complete Analyzer. On the other core runs the basic spectral data handling software. The Graphical User Interface (GUI) software is installed on another PC in the control room or in the laboratory that is on the same network. On this PC the concentration of the constituents is actually determined. Figure 8: SpectraFlow GUI Samples 6. SpectraFlow Scope of Supply See attachment Scope of Supply 7. Supply needed from others See attachment Scope of Supply 8. SpectraFlow Analyzer Guarantees and their Verification See attachment Performance Verification Page 9 of 9