Abstract: A method and apparatus for damping vibration in a paper machine. The apparatus having a dynamic damper which includes a weight suspended by a spring. The spring constant of the spring is changed by means of a control device in order to tune the natural frequency of the dynamic damper. The dynamic damper is tuned to a frequency that is substantially equal to a multiple of the rotational frequency of the roll in the paper machine that is being damped.

Abstract: The surface of a web is monitored by a fault detection system (20), a machine condition monitoring system, a quality measurement system, a web moisture measurement and/or a web temperature measurement and the soiled part of the surface of the roll is detected and localized by means of a soiling monitoring apparatus (31, 35; 60). A control system (41) controls a cleaning device (40) to remove the detected soiling. As a web (W) travels in a paper or board production or finishing process or in finishing machinery the web and/or the surface of the roll is monitored and after a detected deviation the surface thereof is momentarily spread with a liquid while machinery is running at the same time as the web (W) travels over said roll surface.

Abstract: The present invention provides a method making stratified paper by redistributing the pulp suspension inside the headbox nozzle using acoustic radiation waves. Acoustic radiation forces fractionate fibers based on fiber radius. The acoustic radiation waves separate the fibers by pushing the coarse and longer fibers to the inner area while fines and smaller fibers remain in the outer area. This has a similar effect of multi-layer stratification headbox, and provides paper with a smoother surface.

Abstract: Machine and process for the production of a tissue web that includes a drying cylinder and a press shoe arrangement. The press shoe arrangement and the drying cylinder are arranged to form a nip with lateral edge areas. A plurality of contact pressing elements are arranged to exert pressing pressures across the nip, a measuring device is structured and arranged to measure pressing pressures resulting in at least the lateral edge areas, and at least one of a control and regulating device is structured and arranged to locally adjust the pressing pressures in the lateral edge areas by adjusting pressing pressures exerted by contact pressing elements assigned to the lateral edge areas. The instant abstract is neither intended to define the invention disclosed in this specification nor intended to limit the scope of the invention in any way.

Abstract: A method for producing and testing a fiber bed, includes a housing, a main inlet passage and a main outlet passage, a cavity in the housing in fluid connection with the inlet and outlet passages, a body rotatably arranged in the cavity, the body being arranged with a through-going passage having first and a second opening, a screen arranged in the through-going passage, and elements for measuring properties of the fiber bed. The method includes positioning the body so that the first opening is connected to the main inlet and the second opening is connected to the main outlet, creating a first passage, leading a fiber suspension through the first passage in order to produce a fiber bed on the screen, measuring the properties of the bed, rotating the body such that the second opening is connected to the main inlet and the first opening is connected to the main outlet and creating a flow through the first passage for removing the fiber bed from the screen through the outlet.

Abstract: A system for making a paper web has at least one endless wire which is moved over load bearing and guide rolls. A pulp supply apparatus applies pulp to the wire. Suction devices and ceramic scrapers are arranged along the wire. There may also be present devices for the application, controlled by valves, of a coolant, in particular water, to the wire and the scrapers. At least some of the scrapers are constructed with at least one temperature sensor, whose output is connected to a display device or to a control unit.

Abstract: Machine and process for operating machine having at least one roll and an opposing surface arranged to form at least one nip. The machine includes at least one roll and an opposing surface arranged to form at least one nip. A sound measuring device is arranged to conduct sound measurements in at least one of an area of the at least one roll and an area of the at least one nip to monitor vibrations in the at least one roll and/or in the at least one nip. The instant abstract is neither intended to define the invention disclosed in this specification nor intended to limit the scope of the invention in any way.

Abstract: In a paper or board machine, the cross-direction profile of a flow channel defined between a first dewatering element (52, 53) situated inside a first forming wire loop (50) and a second dewatering element (64, 65) situated inside a second forming wire loop (60) is measured, and the location and/or the position of the blade element (64, 65) is adjusted based on the measurement result in order to regulate the thickness profile of a stock flow. The measurement can be by passing an alternating current of low frequency to a current rail situated in the second dewatering element (64, 65) and by measuring the strength of the magnetic field created by it by at least two measuring devices which have been placed either in the first dewatering element (53) or, when the first dewatering element is a forming roll (52), in the same dewatering element (64) as the current rail.

Abstract: A method and system for controlling one or more properties of a sheet of material to be manufactured on a sheet-making machine is disclosed. Actuators to control the sheet properties are arrayed in the cross-direction of the machine. Properties data about one or more properties of the sheet of material are measured and both the magnitude of an actuator control action and the cross-direction shape of an actuator control action are controlled to minimize the variation of the measured properties data from a desired target for each of the one or more properties.

Abstract: The invention relates to a process for measuring and controlling the nip pressure in the press of a paper machine, particularly in a shoe press, across and/or along the web running direction. It is largely characterized by the hydraulic, static pressure being measured at reference points through measurement boreholes in the press nip and adjusted continuously. In addition, the invention relates to a device for carrying out the process.

Abstract: A process is modeled by a dynamic model, handling time dependent relations between manipulated variables of different process sections (10A-D) and measured process output variables. Suggested input trajectories for manipulated variables for a subsequent time period are obtained by optimizing an objective function over a prediction time period, under constraints imposed by the dynamic process model and/or preferably a production plan for the same period. The objective function comprises relations involving predictions of controlled process output variables as a function of time using the process model, based on the present measurements, preferably by a state estimation procedure. By the use of a prediction horizon, also planned future operational changes can be prepared for, reducing any induced fluctuations. In pulp and paper processes, process output variables associated with chemical additives can be used, adapting the optimization to handle chemical additives aspects.

Abstract: An apparatus for measuring wear of a doctor blade includes measuring members placed around the doctor blade for measuring at least one dimension of the doctor blade. The measuring members are arranged to permit longitudinal movement of the doctor blade between the doctor blade and the measuring members. In addition, measurement sensors are connected to the measuring members to obtain a continuous measurement result when the doctor blade or the apparatus is moved. The invention also relates to a method in the measurement of wear of a doctor blade and in controlling a paper machine.

Abstract: A method and system for determining trace oversize contaminant particles in a paper-making pulp employs a screen assembly having a screen housing with a screen mounted therein, and ports for introduction of aqueous pulp and rinsing and flushing fluids, and for withdrawal of screened aqueous pulp, the screen housing has no port designated for the sole purpose of removing accumulated contaminant particles from the screen housing; instead the port employed for introduction. of aqueous pulp and which may also be employed for introduction of rinsing fluid to the housing, is employed as the flushing port for removal of contaminant particles.

Abstract: A web making machine is monitored to identify at least one cross-machine direction (CD) actuator that is developing local mapping problems. The identified CD actuator and a segment of surrounding actuators are probed to determine a performance curve for the actuator. The center of an insensitivity region of the performance curve is selected as an optimal mapping alignment setting for the identified actuator with the setting for the actuator being updated. Global smoothing may also be accomplished by probing a global smoothness factor to generate a corresponding performance curve that is then similarly used to select an optimal value for the smoothness factor.

Abstract: Process and apparatus for manufacturing a fibrous material web. The apparatus includes an automatic formation regulator, and the process includes on-line measuring of formation of the fibrous material web, utilizing the on-line measured formation as a controlled variable, and maintaining the formation at a preselectable target level via the automatic formation regulator.

Abstract: A method for producing a pulp molded article is disclosed. The method comprises the steps of forming and drying a pulp molded precursor (15). The drying step includes a first step and a second step. In the first step, the precursor (15) is set in a cavity of a heating mold, and is hot-pressed. The cavity has a configuration in conformity to the contour of the pulp molded article to be produced. In the second step, the hot-pressed precursor (15) is taken out from the heating mold and is heat-dried in a drying furnace.

Abstract: A method and an apparatus for controlling a moisture profile of a paper web, in which the moisture profile of the paper web prior to drying is measured. The measurement is carried out with a measuring device, which measures a cross-direction profile of the web substantially simultaneously. On the basis of the measurement, the moisture profile of the paper web is controlled prior to drying the paper web.

Abstract: The invention provides a method for predictively assessing one or more characteristics of wood pulp produced from solid wood. The method comprises the steps of determining the velocity of sound through the solid wood, and assessing characteristic(s) of wood fiber or wood pulp produced from the wood by reference to the velocity of sound through the solid wood. The method may also comprise the steps of causing a sound wave to be transmitted through the wood, determining the velocity of the sound wave through the wood, and comparing the result to stored information on fiber characteristic(s) versus sound velocity through the wood-type to determine the fiber characteristic(s) for the wood.

Abstract: Method and apparatus for determining characteristics of a running material web, the apparatus including at least one measuring device. The at least one measuring device is movable and has at least two degrees of freedom of movement. Each of the at least two degrees of freedom of movement is at least one of a rotary movement and a linear movement. The at least one measuring device is adapted to detect, at a plurality of measurement locations, data relating to at least one measured parameter. The at least one measuring device detects data about at least one of the following measured parameters: measured parameters which relate to a characteristic value of air in a region of the material web; measured parameters which relate to the material web; and other measured parameters. The method includes detecting, at a plurality of measurement locations and using the at least one measuring device, data relating to at least one measured parameter.

Abstract: A paper/board machine headbox (10) has a stock inlet header (J), a tube bank (11), a turbulence generator (13) and a slice opening (14) which is provided with a profile bar. The headbox (10) is provided with cross direction measuring sensors (D1, D2; Dmn), by means of which the flow rate profile of the headbox (10) is determined, and the profile bar of the slice opening (14) of the headbox (10) is adjusted in the cross direction on the basis of the thus determined flow rate profile. The headbox (10) is provided with measuring sensors (D1, D2; Dmn) for determining the cross direction flow rate profile of the headbox (10) and with means for adjusting the profile bar on the basis of the flow rate profile.

Abstract: In the manufacture of a paper or board web (W), the web is slit or cut, the rising/lowering (H) of the edges of a slit/cut gap (C) formed at the slitting/cutting point or the width (L) of the gap is measured by means of a measurement device (21A; 21B; 21C), and the curl of the paper or board web (W) is regulated based on the result of measurement. A paper or board machine line has means for regulating curl in the web (W); means for slitting or cutting the paper or board web and for measuring the rising/lowering (H) of the edges of a slit/cut gap (C) formed at the slitting/cutting point or the width (L) of the slit/cut gap (C) in connection with the manufacture of the web (W) in order to regulate the curl of the web (W) based on the result of measurement.

Abstract: Process and apparatus for monitoring the condition of a rotating belt in a paper or cardboard machine. The process includes recording data related to a condition of the belt, and creating an at least two-dimensional image of the belt condition from the recorded condition data. The image depicts a condition characteristic in a machine travel direction and a condition characteristic in a machine crosswise direction. The instant abstract is neither intended to define the invention disclosed in this specification nor intended to limit the scope of the invention in any way.

Abstract: The invention relates to a method for monitoring the operation of a doctor assembly in a paper machine. In the method, the operation of the doctor assembly (16) is monitored. In case of a malfunction, the paper machine's (10) control devices (14-14′, 15) are used to carry out the necessary measures for eliminating the malfunction and carrying out repair and/or protective measures. In addition, detector devices (20) are arranged in connection with the doctor assembly (16), to detect a malfunction. The detector devices (20) are connected to the control devices (14-14′, 15) of the paper machine (10), in order to carry out the said measures automatically. The invention also relates to doctor assemblies in a paper machine for implementing the method.

Abstract: A shoe press includes: a first member; a second member; a substantially cylindrical belt; and a processing unit. The first member has a convex pressing surface. The second member includes a shoe with a concave pressing surface substantially complimentary to the convex pressing surface. The second member further includes a pair of substantially circular head plates rotatably mounted on axially opposed ends thereof. The belt is fixed to, extends between, and is rotatable with the head plates such that a portion of the belt passes between the convex pressing surface and the concave pressing surface. The belt includes embedded therein a communications cable having a plurality of sensors configured to generate signals responsive to an operating parameter of the shoe press. The processing unit is in communication with the communications cable and processes signals generated by the sensors.

Abstract: A monitoring apparatus is provided which can ensure the prevention of a paper break even in a poor installation environment. A light source (9) illuminates light (9a) on a lateral edge (1a) of wet paper (1) and a camera (5) captures light (9b) reflected therefrom. The camera (5) is a micro camera and completely covered by a camera box (10). The camera box (10) has an observation window (10a) which is made of a transparent member, at the lens side (5a) of the camera (5). The outer surface of the observation window (10a) is coated and an air curtain (12a) that flows from above to below prevents staining caused by mist. The air curtain (12a) is formed in such a manner that air that is continuously supplied inside a cover (11) flows along the outer surface of the observation window (10a) from an opening portion (11a).

Abstract: A property of a paper web is measured using one or more reflectance measurement sensors emitting measuring beams onto the web and receiving the beams reflected from the web, from which the web property is deduced. The web is supported on a web support during the measurement, such as on a passive or active airfoil or fabric. One or more measurement sensor(s) can be integrated within an active airfoil, and can comprise a plurality of optical fibers having sensing ends arranged in the airfoil such that the sensing ends of the fibers face the moving paper web through one or more apertures in a web-supporting panel of the airfoil. Alternatively, a traversing sensor can be mounted within the airfoil. Other embodiments include a reflectance sensor mounted adjacent an airfoil or other web support such as a through-air drying fabric or a support belt for the web.

Abstract: Method for determining a characteristic value for a binding force potential of paper fibers in a fibrous suspension. The method includes measuring an air content of the fibrous suspension and deriving the characteristic value from the measuring.

Abstract: Process and apparatus for determining properties of a traveling material web. The process includes simultaneously illuminating a plurality of measuring points on the material web with electromagnetic radiation, and imaging, through at least one optical device, the plurality of measuring points on one detection surface of at least one detector. The device includes at least one radiation source for illuminating a plurality of measuring points on the material web, at least one detector having a detection surface, and at least one optical device for imaging of the measuring points on the detection surface of the at least one detector.

Abstract: The measuring device comprises at least one measuring head having a reference part, which comprises a reference surface against which the moving web is supported. The reference surface comprises a measuring area in the inside of which the property of the web is measured. The reference part is arranged in connection with the measuring head in such a way that below the reference part, there is a substantially open air space. The measuring head comprises means for generating negative pressure in the air space below the reference part, and the reference part comprises holes formed through it, in such a way that the negative pressure generated in the air space affects through the reference part the space between the reference surface and the moving web in such a way that the web is supported against the reference surface substantially over the whole area of the measuring area.

Abstract: The present invention relates to a method and apparatus for controlling the operation of an approach system of a paper machine or the like web formation apparatus. Especially preferably the method of controlling the operation of an approach system according to the invention is applicable to be used in connection with paper and paperboard machines as well as in connection with various apparatuses performing non-woven webformating.

Abstract: A dry end of a tissue machine is made shorter by close-coupling a reel-up to the drying section and supporting the web from the drying section to the reel-up by a foil or a belt such that web stability is maintained, thus allowing high-speed operation. The foil's downstream edge can form a nip with the paper roll and nip load can be controlled by controlling pivotal movement of the foil. The reel-up can include a calendering belt for calendering the web as it passes through a nip between the belt and a reel drum supported on the belt, and a rotatable reel spool on which a paper roll is wound in nipping engagement with the reel drum. Alternatively, the reel drum can be eliminated and the paper roll can be supported on the belt. A composite shaftless core for winding is also disclosed.

Abstract: System and method of operating a machine for manufacturing and/or refining a material web wherein the machine includes at least one machine section. The method includes arranging a plurality of measurement zones in series along a process direction and detecting data in a region of the at least one machine section via at least one measurement zone of the plurality of measurement zones. The data concerns at least one measured parameter relating to the manufacture or refinement of the material web. The system includes a plurality of measurement zones arranged in series along a process direction of the machine. At least one of the plurality of measurement zones is located in the at least one machine section. At least one measurement device for detecting data is located in at least one of the plurality of measurement zones. An evaluation unit is provided for evaluating the data.

Abstract: The invention relates to a method in a paper or board machine, in which method water is removed from a paper or board web (W) by pressing in a press section (30), in which pressing stage the web (W) is pressed in at least one press nip (35; 36), and in which method the web (W) is dried after pressing by impingement drying, in which method the web (W) is passed as a closed draw from the press section (30) to a dryer section (40), and the method applies full-width threading from the press section (30) to the dryer section (40). The web (W) is dried by impingement drying by means of impingement units (46) placed around at least one large-diameter impingement roll (45). In the method, the web (W) is passed after impingement drying as a closed draw through the dryer section (40) to a calender (60), and in the method threading is accomplished as of full width through the dryer section (40).

Abstract: A process and device to detect the presence of a fibrous material web in machines for manufacturing the same, whereby the fibrous material web is guided by at least one continuously circulating belt. The process includes measuring at least one of (1) a temperature of a side of the fibrous material web opposite the at least one belt while it is being supported by the at least one belt, (2) a temperature of a material web supporting side of the side of the at least one belt after transfer of the fibrous material web to a following unit, and (3) the temperature of a side of the at least one belt opposite the fibrous material web supporting side of the at least one belt. The process also includes detecting a change in the at least one measured temperature as an indicator of the presence or lack of fibrous material or the strip in an area in the machine in the vicinity of the measuring.

Abstract: The invention relates to a method and device for the merging and finishing of at least two paper webs (1, 2, 3, 4), controlled in the longitudinal register, which are distinctly different in quality and in finishing steps to be undertaken. The device comprises at least two web-specific processing regions (13A, 13B, 13C), a merging unit (21), a common processing region (22), controlled in the longitudinal register and means for the control of the longitudinal register (14), essentially comprising one longitudinal register sensor per paper web. Markings are placed on the paper web with periodic separations. Longitudinal register sensors (14) recognise said markings and transmit signals to the control unit, which determines possible variations and controls the means for regulation of the longitudinal register in such a way that variations in the longitudinal register are compensated.

Abstract: A system for making a paper web has at least one endless wire which is moved over load bearing and guide rolls. A pulp supply apparatus applies pulp to the wire. Suction devices and ceramic scrapers are arranged along the wire. There may also be present devices for the application, controlled by valves, of a coolant, in particular water, to the wire and the scrapers. At least some of the scrapers are constructed with at least one temperature sensor, whose output is connected to a display device or to a control unit.

Abstract: In a paper or board machine, the cross-direction profile of a flow channel defined between a first dewatering element (52, 53) situated inside a first forming wire loop (50) and a second dewatering element (64, 65) situated inside a second forming wire loop (60) is measured, and the location and/or the position of the blade element (64, 65) is adjusted based on the measurement result in order to regulate the thickness profile of a stock flow. The measurement can be by passing an alternating current of low frequency to a current rail situated in the second dewatering element (64, 65) and by measuring the strength of the magnetic field created by it by at least two measuring devices which have been placed either in the first dewatering element (53) or, when the first dewatering element is a forming roll (52), in the same dewatering element (64) as the current rail.

Abstract: The invention concerns a method for conditioning of a roll, in particular of a roll (10) in a paper machine or in a paper finishing device. In the method the face/coating on the roll of the paper machine is cleaned and/or ground. In the method, the cleanliness and/or condition of the roll (10) is/are measured continuously during operation and, based on the measurement results, the roll face/coating is cleaned and/or ground so that the roll (10) remains constantly in good condition and the level of quality of the paper remains at the desired level. The invention also concerns a device for conditioning of a roll, in particular of a roll in a paper machine and/or in a paper finishing device, which device (20) comprises means for cleaning and/or grinding the roll. The device (20) consist of an assembly (20) of devices which comprises a cleaning/conditioning unit (24, 23, 29), a control unit (33), and measurement units (30, 31, 32), and the device operates continuously and can be operated during running.

Abstract: Method and system for controlling web formation in the forming section of a paper machine includes measuring the amount of white water occurring during drainage in at least one drainage region of the forming section; and carrying out the web formation control on the basis of the white water measurement.

Abstract: Machine and process for at least one of producing and finishing a fibrous material web. The machine includes a press section, for dewatering the fibrous web, with a press nip, a former, located before, relative to a web travel direction, the press section for sheet formation, and a dryer section, located after the press section for drying the fibrous material web including a first dryer section having no more than three dryer cylinders. Two press rolls are arranged to form the press nip, and at least one press felt is located on each surface of the material web, such that the material web and the at least one press felt on each side of the material web are guided through the press nip. The fibrous material web is dewatered in the former to a dry content of at least approximately 18%, partially loops around the no more than three dryer cylinders, and is constantly supported from the former to an end of the first dryer group.

Abstract: The invention relates to a method and a device for the processing of a fiber web or a suspension layer in a paper-, cardboard- or coating-machine or a size press for influencing the profile of the properties of a web by means of at least one sectional, directed acoustic (sound) field. In other words, the acoustic field is narrower than the width of the fiber web or the suspension layer, and the acoustic field affects components of the fiber web or suspension layer at a defined angle. Profiles of the properties of a web influenced by acoustic fields are lamination, spatial orientation, fiber orientation, dry content, breaking length ratio, flocculation and color coat thickness. Furthermore, the introduction of a signature mark into the fiber web or suspension layer is possible.

Abstract: An apparatus for modifying a traveling position of a paper web in a paper web processing machine is provided. The apparatus is capable of easily attaching a detection means; requiring no operation of the paper web processing machine to determine an accurately adjusted position for attachment; and extremely easily setting a desired size of a tolerable deviation range of a practical position of a side edge to an originally expected position of the side edge when the sheet travels. The apparatus includes a traveling position modification means for modifying a position of a side edge of a paper web traveling toward a processing section in a paper web processing machine; a detection means for detecting the position of the side edge of the paper web; and a control means connected to the modification means and the detection means for controlling the modification means based on a value detected at the detection means.

Abstract: The invention relates to a method and an apparatus for measuring the amount of silicone coating on a moving paper or board web. In the invention, the characteristics of the coating (4a) are measured by means of reflection measurement or transmission measurement. The amount of the silicone in the coating is measured by measuring an absorption peak that is characteristic of the silicone in the mid-infrared range.

Abstract: Machine and process for the production of a tissue web that includes a drying cylinder and a press shoe arrangement. The press shoe arrangement and the drying cylinder are arranged to form a nip with lateral edge areas. A plurality of contact pressing elements are arranged to exert pressing pressures across the nip, a measuring device is structured and arranged to measure pressing pressures resulting in at least the lateral edge areas, and at least one of a control and regulating device is structured and arranged to locally adjust the pressing pressures in the lateral edge areas by adjusting pressing pressures exerted by contact pressing elements assigned to the lateral edge areas. The instant abstract is neither intended to define the invention disclosed in this specification nor intended to limit the scope of the invention in any way.

Abstract: A method for the manufacture or treatment of a material web, in particular of a paper or a cardboard web, while using a respective machine, in particular a paper machine, including the step of measuring the hardness and/or the compactness of at least one clothing, in particular of at least one felt, fabric, belt and/or the like, of the machine.

Abstract: A method for threading a running paper web from a preceding section to a following section of a paper-making or paper-finishing machine, includes the steps of: providing a threading tail of the running paper web by cutting it from the running paper web at at least one of its edges; providing at least one sensing element for gaining data from at least one property of the threading tail and/or threading process; transferring the gained data into a data collecting system and/or into an analysis system; and using the data for influencing the at least one property of the threading tail and/or the threading process.

Abstract: A method and apparatus for manipulating dryer steam pressure in a paper machine during grade change, wherein change in moisture percentage is determined from a change in production amount during grade change, dryer stream pressure is manipulated so as to cancel the change in the moisture percentage, and production amount during grade change is calculated from basis weight and machine speed before and after grade change, whereby moisture percentage is kept constant during grade chagne so that sheet breaks are avoided and downtime is reduced.

Abstract: The invention relates to a method and a device for measuring concentrations especially in a pulp suspension, from which a sample (3) has been taken. The sample (3) is collected in a measuring vessel (2), in which a piston (6) is guided upwards and downwards in order to press the sample (3) from each direction through a measuring sensor (5) connected at the side of the measuring vessel via communicating tubes (4,4′) connected in an upper and an lower position to the measurement vessel (2), whereby the sample (3) is stirred totally for eliminating of a flocculation in the same, whereupon a measurement of the concentration of the sample (3) is made either during the movement upwards or downwards of the piston (6) in the measuring vessel (2) and first when the speed of the sample (3) through the measuring sensor (5) is constant and the sample has been homogenized at least after some movement upwards and downwards of the piston.

Abstract: A method and an apparatus are provided for measuring the amount of entrained gases in a liquid sample. A conduit defining a volume is provided. The conduit has an inlet at a lower end thereof and an outlet at an upper end thereof. Liquid sample is made to flow into the inlet, through the conduit, and out of the outlet. The weight of the liquid sample in the conduit is determined during a flow of liquid sample through the conduit to obtain a first measurement. Thereafter, a difference between the first measurement and a predetermined weight value representing a weight of the same liquid sample flowing through the conduit but containing no entrained gases is determined to obtain a calculated weight of entrained gases in the liquid sample flowing through the conduit.

Abstract: Process and apparatus for monitoring dewatering in a wet end section of a web production machine. The process includes measuring water flowing into the wet end section, measuring water flowing out of the wet end section, measuring conductivity of the wet web entering the wet end section, measuring conductivity of the water flowing into wet end section, measuring conductivity of water flowing out of the wet end section, and determining a water balance from the measured quantities, which is indicative of dewatering in the wet end. The apparatus is arranged to perform the process.