Abstract: A grinding circuit comprises a grinding mill having a shaft in a grinding chamber, a cyclone for receiving circuit feed material and for feeding said circuit feed material further in the grinding circuit, and monitoring devices. The grinding mill process comprises pumping circuit feed material from a feed tank to the cyclone upstream of the mill, and pumping the circuit feed material forming slurry into the grinding mill for grinding the slurry into finer particles. The method of controlling the grinding mill process comprises monitoring at least one operational parameter, and controlling particle fineness online by adjusting at least one of the following operational parameters: flow rate of the circuit feed material, density of the circuit feed material, shaft speed, filling rate in the grinding mill, milling density and retention time.

Abstract: The invention relates to a method of controlling a grinding mill process in a grinding circuit, which said grinding circuit comprises at least a grinding mill (6) having a shaft (4) in a grinding chamber (2), said grinding circuit (G) further comprises a cyclone (11) for receiving circuit feed material and for feeding said circuit feed material further in the grinding circuit (G), and monitoring devices. The grinding mill process comprises at least following steps: pumping circuit feed material from a feed tank to the cyclone (11) upstream of the mill, and pumping the circuit feed material forming slurry into the grinding mill (6) for grinding the slurry into finer particles.

Abstract: A chemical or chemical compound (L) is supplied via at least two displacement pumps (1, 4) to a common supply line (11), through which the chemical or chemical compound (L) is supplied to the operating device (12) of a fibrous web machine. Each pump (1, 4) has a corresponding electric actuator (2, 5) which is equipped with a corresponding control drive (3, 6). The fibrous web machine has a measuring device (8; 8a, 8b) for determining the phase angles of at least the first and second actuators (2,5). A control signal based on the determined phase angle information is formed and transmitted to the first control drive (3), based on the control signal, the difference between the first and second electric actuators (2, 5) is adjusted. An electric synchronization signal between the control drives (3, 6) maintains the difference between the phase angles electric actuators (2, 5).

Abstract: Method and arrangement for separating impurities from the machine circulation of a processing agent of a processing station used in processing paper or board, in which method the processing agent is led from a reservoir (1) to the processing station (2), where it is spread on the surface of the web being processed, and the excess processing agent led to the processing station (2) agent is led back to the reservoir (1). The flow of processing agent coming from the processing station (2) is led to at least one pressure sieve (6), which is located below the level of the processing station (2), in such a way that the feed pressure of the processing agent is created on the basis of the difference in height between the station (2) and the pressure sieve (6).

Abstract: Method and arrangement for separating impurities from the machine circulation of a processing agent of a processing station used in processing paper or board, in which method the processing agent is led from a reservoir (1) to the processing station (2), where it is spread on the surface of the web being processed, and the excess processing agent led to the processing station (2) agent is led back to the reservoir (1). The flow of processing agent coming from the processing station (2) is led to at least one pressure sieve (6), which is located below the level of the processing station (2), in such a way that the feed pressure of the processing agent is created on the basis of the difference in height between the station (2) and the pressure sieve (6).

Abstract: A chemical or chemical compound (L) is supplied via at least two displacement pumps (1, 4) to a common supply line (11), through which the chemical or chemical compound (L) is supplied to the operating device (12) of a fibrous web machine. Each pump (1, 4) has a corresponding electric actuator (2, 5) which is equipped with a corresponding control drive (3, 6). The fibrous web machine has a measuring device (8; 8a, 8b) for determining the phase angles of at least the first and second actuators (2,5). A control signal based on the determined phase angle information is formed and transmitted to the first control drive (3), based on the control signal, the difference between the first and second electric actuators (2, 5) is adjusted. An electric synchronization signal between the control drives (3, 6) maintains the difference between the phase angles electric actuators (2, 5).

Abstract: An apparatus and method for deaeration of treatment agents applied to webs of paper and board, having an inlet manifold (3), an accept-fraction manifold (4), and a reject-fraction manifold (5). For deaeration the assembly uses a plurality of air separator units (12) connected to the manifolds so as to allow admission of the treatment agent to the air separator units (12) from the inlet manifold (3) and discharge of the accept and reject fractions formed in the air separator units (12) respectively to the accept-fraction and reject-fraction manifolds (4, 5). A cut-off valve (18) is mounted on at least the inlet manifold (3), between two parallel-operating air separator units (12), so as to permit cutting off the flow through the manifold (3) at this location of the cut-off valve, dividing the plural air separator units (12) by the cut-off valve (18) into two groups.

Abstract: An assembly is disclosed for an apparatus used for deaeration of treatment agents applied to webs of paper and board, the assembly comprising at least one inlet manifold (3), at least one accept-fraction manifold (4), and at least one reject-fraction manifold (5) with associated framework structures; also a method is disclosed for operating the assembly. For deaeration the assembly uses a plurality of air separator units (12) connected to the manifolds so as to allow admission of the treatment agent to the air separator units (12) from the inlet manifold (3) and discharge of the accept and reject fractions formed in the air separator units (12) respectively to the accept-fraction and reject-fraction manifolds (4, 5).

Abstract: The present invention relates to a method and apparatus for measuring the properties of a composition or a component thereof used in the processing of a paper or board web. According to the invention, a sample of the composition to be measured is taken into a measurement apparatus, the composition is measured at least for its density, viscosity, dry solids content and gas content, and is then passed out from the measurement apparatus.

Abstract: A method and apparatus for separating foreign material from coating mix flow circulating in the machine circulation of a coating station (7) in coaters used for coating a web of paper or board. Coating mix is conveyed from a tank (1) to a coating station, where it is applied to the surface of the web to be coated, and the excess of the coating mix conveyed to the coating station (7) is returned to the tank (1). The coating mix flow incoming from said tank (1) to the coating station is screened by at least one pressure screen (5) and the rejects fraction of the coating mix flow is discharged from the pressure screen (5). A portion of the coating mix flow circulating in the machine circulation is passed through a vibrating screen (13) and the accepts fraction of the vibrating screen is returned back to the machine circulation. The invention offers high efficiency in the removal of elongated foreign matter particles from the machine circulation of coating mix.