Measurement system for and method of measuring moving web

A measurement system for measuring a moving web, wherein the measurement system comprises an X-ray sensor configured to perform repeatedly electromagnetic transmission measurements of the web of nonwoven fabric and/or cellulose, water and one or more ash components;

• the optical sensor being configured to perform repeatedly optical absorption measurements of the web within an optical range, which is configured to include one or more characteristic optical absorption bands of at least one desired material component of the web and at least one reference band for the characteristic optical absorption bands, and the optical sensor being configured to detect a plurality of optical bands that are distributed over the optical range regularly or irregularly in an independent manner of both the one or more characteristic absorption bands and the at least one reference band of said at least one desired material component, the number of the optical bands of the optical range being equal to or larger than the combined number of the one or more characteristic optical absorption bands of the at least one desired material component and the at least one reference band, the optical sensor being, in that manner, configured to distinguish the one or more characteristic optical absorption bands of the at least one desired material component and the at least one reference band from each other;
• at least one of the X-ray sensor and the optical sensor is configured to traverse across the moving web in a transverse direction of the web;
• and a data processing unit is configured to receive data on the repeated measurements, fuse the data from the X-ray sensor and the optical sensor together, and form information on at least one of the following based on said fused data on absorption:
• basis weight of the web and a weight per unit area of at least one of the desired material components of the web, where the information on basis weight is based on the measurement of the X-ray sensor.

A measurement method of measuring a moving web, the method comprising performing, by an X-ray sensor, repeatedly electromagnetic transmission measurements of the moving web of nonwoven fabric and/or cellulose, water and one or more ash components;

• performing, by the optical sensor, optical absorption measurements of the web within an optical range, which includes one or more characteristic optical absorption bands of at least one desired material component of the web and at least one reference band for the characteristic optical absorption bands;
• detecting, by the optical sensor, a plurality of optical bands that are distributed over the optical range regularly or irregularly in an independent manner of both the one or more characteristic absorption bands and the at least one reference band of said desired material components, the number of the optical bands of the optical range being equal to or larger than the combined number of the one or more characteristic optical absorption bands of the at least one desired material component and the reference bands for enabling the optical sensor to distinguish the one or more characteristic optical absorption bands of the at least one desired material component and the at least one reference band from each other;
• performing transversing, by at least one of the X-ray sensor and the optical sensor, across the moving web in a transverse direction of the web;
• receiving, by a data processing unit, data on the repeated measurements;
• fusing, by the data processing unit, the data from the X-ray sensor and the optical sensor together;
• and forming, by the data processing unit, information on at least one of the following based on the fused data on absorption:
• basis weight of the web and a weight per unit area of at least one of the desired material components of the web.

A measurement method of measuring a moving web, the method comprising performing, by an X-ray sensor, repeatedly electromagnetic transmission measurements of the moving web of nonwoven fabric and/or cellulose, water and one or more ash components;

• performing, by the optical sensor, optical absorption measurements of the web within an optical range, which includes one or more characteristic optical absorption bands of at least one desired material components of the web and at least one reference band for the characteristic optical absorption bands;
• detecting, by the optical sensor, a plurality of optical bands that are distributed over the optical range regularly or irregularly in an independent manner of both the one or more characteristic absorption bands and the at least one reference band of said desired material components, the number of the optical bands of the optical range being equal to or larger than the combined number of the one or more characteristic optical absorption bands of the at least one desired material component and the reference bands for enabling the optical sensor to distinguish the one or more characteristic optical absorption bands of the at least one desired material component and the at least one reference band from each other;
• transversing, by at least one of the X-ray sensor and the optical sensor, across the moving web in a transverse direction of the web;
• receiving, by a data processing unit, data on the repeated measurements;
• fusing, by the data processing unit, the data from the X-ray sensor and the optical sensor together;
• and forming, by the data processing unit, information on at least one of the following based on said fused data on absorption:
• basis weight of the web and a weight per unit area of at least one of the desired material components of the web, where the information on basis weight is based on the measurement of the X-ray sensor.