Quality control systems (QCS)
The ANDRITZ quality control system delivers reliable and precise measurements (profiles) of pulp sheet parameters.
The QCS is a smart processing center for processing information and delivering reliable and precise measurements of sheet parameters, for example basis weight, moisture, temperature or brightness out of the dryer. Data from the scanner is processed and used for the cross and machine direction control.
A general overview of QCS
The QCS consists of several measuring sensors, namely a basis weight sensor, a microwave moisture sensor, a precision color sensor and a sheet temperature sensor.
Basis weight sensor
- Following the principle of the radioactive transmission, more precisely the beta absorption (prometium/krypton/strontium), to measure the mass per unit area of moving web
- A beta radiation source emits a stream of beta particles and as the particles pass trough the sheet, the fibers absorb some of them. The receiver collects those particles that pass through the sheet and the amount of collected particles gives information about the basis weight value
- Extremely high signal to noise resolution ratio
- Excellent streak resolution
- Complete compensation for environmental sources of error
- High speed of response
The QCS for paper board machines
Microwave moisture sensor
- The sensor is a microwave transmission sensor
- Following the principle that moisture in a sheet absorbs specific infrared wavelengths while others are unaffected
- Sensor measures the moisture content of a moving web by measuring the microwave resonance changes that occur with moisture content changes
- Provides accurate and high resolution measurement of moisture under all environmental conditions
The QCS for tissue machines
Precision color sensor
- Delivers accurate measurements of appearance qualities like brightness
- Following the principle of reflectance measuring
- The sensor receives spectra from two spectrophotometers at the same time to deliver reflectance measurements of the same spot on sheet
- Fluorescence measuring is given through merging the beams of two light sources, a continuous daylight source and a pulsed UV-enrichment source
- The air vortex sheet stabilizer is used to ensure a non-contacting, repeatable, non-intrusive measurement