JP2005248349A - Paper machine and antifoamer-adding system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a paper machine capable of constantly, continuously and accurately measuring the content of gas in raw water by a simple construction, and capable of adding an antifoamer in an accurate amount; and to provide a paper-making method and an antifoamer-adding system. <P>SOLUTION: The amount of the bubble contained in the raw water is calculated based on a value of pressure and a level Lh of the liquid surface by keeping the level Lh of the liquid surface at the height of a water outlet 14 by overflowing the raw water always from the water outlet 14 of a raw water container 16, and detecting the pressure of the raw water by a liquid pressure sensor 18 installed in a detection level L lower than that of the water outlet 14. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a paper machine, a paper making method, and an antifoaming agent addition system for performing papermaking while adding an antifoaming agent to raw water.

  Conventionally, paper products are produced by papermaking raw water called white water containing pulp. In order to make effective use of water resources, the paper-made white water may be reused after paper making and after processing such as filtration, addition of chemicals, and stirring.

  Such raw water such as white water or paper-made white water is mixed with bubbles due to various causes such as stirring, and the bubbles are a factor of deteriorating the quality of the product paper. On the other hand, a papermaking method is known in which papermaking is performed while removing bubbles by adding an antifoaming agent to raw water.

  For example, a predetermined amount of a self-emulsifying type antifoaming agent is added to a pit storing paper-made white water by a pump, and at the same time, the amount of bubbles in the paper-making system is measured by a bubble detector, and the output of the pump is controlled by a controller Thus, a method is known in which an emulsion type antifoaming agent is added in proportion to the amount of bubbles in a papermaking liquid (for example, see Patent Document 1).

  As a dynamic metering device for the bubble content in the flowing liquid, a capacity flow rate measuring device and a mass flow rate measuring device for determining the apparent density of the flowing liquid containing bubbles in the transport line for engine oil, etc. By installing a pressure adjustment valve that adjusts the pressure of the flowing liquid to a high pressure condition and a low pressure condition, and the bubble content calculation formula, the bubble content and dissolved gas in the flowing liquid containing bubbles under high pressure and low pressure conditions There is known a method for quantifying the amount of foaming of gas (for example, see Patent Document 2).

  Further, a gas content measuring method and a gas content measuring device for measuring the gas content of fluid such as pulp and coating paste are known (for example, see Patent Document 3). This is caused by a pressure change in the fluid caused by a pump or the like, and the transmission time, phase, and attenuation of the microwave signal at this time are measured when the microwave signal passes through the fluid, and are caused by the fluid pressure change. The gas content is determined based on changes in the transmission time, phase, and attenuation of the microwave signal.

JP-A-8-113891 Japanese Patent No. 2643020 JP-T-2001-525934

  However, the bubble detection device in Patent Document 1 is described only by measuring the differential pressure of the detection tank after the paper-made white water is sent to the detection tank, and its specific configuration is not disclosed. . Further, in the inventions disclosed in Patent Documents 2 and 3, there is a problem that it is necessary to generate a pressure change in the fluid, the structure is complicated, and a complicated calculation is required.

  Also, with the conventional bubble detection method, it is difficult to accurately detect the amount of bubbles in the raw material water, and the amount of antifoaming agent added tends to be too large or too small.

  The present invention has been made in view of the above-mentioned conventional problems, and always measures the gas content in raw material water continuously and accurately with a simple configuration, and adds an accurate amount of antifoaming agent. An object of the present invention is to provide a paper machine, a paper making method, and an antifoaming agent addition system.

  The present invention constantly overflows raw water from the outlet of the raw water container, maintains the liquid level of the raw water in the raw water container at the height of the outlet, and is provided at a detection level lower than the outlet. The pressure sensor detects the pressure of the raw water and calculates the amount of bubbles contained in the raw water based on the pressure value and the liquid level of the raw water. In addition, it is measured continuously and accurately, and an optimal amount of antifoaming agent is added to the raw material water.

  In the process of conceiving the present invention, the inventor produces the smaller the fluctuation range of the content of bubbles contained in the raw material water, even if the average value of the content of bubbles contained in the raw material water is equal. I found that the quality of paper products tended to improve.

  The reason why the quality of the produced paper product is improved as the fluctuation range of the bubble content in the raw material water is small is not necessarily clear, but the raw material water is supplied to the papermaking section by stabilizing the bubble content. It is considered that the pressure variation in the inlet and the decurator is suppressed and the surging fluctuation of the fan pump is kept constant, so that the paper making process is stabilized and the quality of the paper product is improved.

  If the amount of the antifoaming agent added is too large or too small relative to the amount of bubbles, the variation in the content of bubbles in the raw material water tends to increase, but according to the present invention, an optimal amount of antifoaming agent is used as described above. Since it can be added to the raw material water, the fluctuation range of the content of bubbles contained in the raw material water is suppressed to a small level, and a paper product with good quality can be produced accordingly. It is also possible to increase the production rate of paper products while maintaining the same quality.

  In addition, according to the present invention, since an optimal amount of antifoaming agent can be added to the raw material water, consumption of the antifoaming agent can be suppressed and production cost can be reduced.

  That is, the following object is achieved by the present invention as follows.

  (1) A paper machine equipped with an antifoaming agent addition system for removing bubbles by adding an antifoaming agent to raw material water, wherein the antifoaming agent addition system is connected to the raw water from the main flow path of the raw material water. A bypass pipe that continuously removes the main flow path, and a gas content measuring device that is disposed in the middle of the bypass pipe and that measures the gas content of the raw water flowing through the bypass pipe, and the main flow An antifoaming agent pump for adding an antifoaming agent to the road, and a control device for controlling the defoaming agent adding amount by the antifoaming agent pump based on the measurement result by the gas content measuring device. The gas content measuring device comprises a raw water container having an inlet of raw water from the bypass pipe and an outlet provided at a higher level than the inlet, and the inlet of the raw water container. Higher and lower than the outlet And a liquid level sensor for detecting a liquid pressure at the detection level and a liquid level control means for controlling the liquid level of the raw material water in the vicinity of the outlet. The apparatus calculates the gas content of the liquid between the detection level of the hydraulic pressure sensor and the liquid level based on the sensor output of the hydraulic pressure sensor and information on the liquid level of the raw water A paper machine comprising:

  (2) The control device is configured to control an antifoaming agent addition amount by the antifoaming agent pump so as to keep a gas content of the raw material water constant. The paper machine described in 1.

  (3) A part of the main flow path is a circulation pipe for paper-made white water, and at least one circulation pump is disposed in the circulation pipe, and the bypass pipe is the circulation pump in the main flow path. The paper machine according to (1) or (2), wherein the paper machine is connected close to the downstream side.

  (4) The main flow path includes a drain pan for receiving paper-made white water from at least one of a wire part and a press part used for paper making, and an outlet of the bypass pipe opens to a part of the main flow path. The paper machine according to any one of (1) to (3), wherein the paper machine is provided.

  (5) The paper machine according to (4), wherein an outlet of the bypass pipe is provided open to the drain pan.

  (6) The liquid level control means controls the flow rate of raw water flowing from the inlet to the raw water container so that the liquid level is constant. The paper machine according to any one of 1) to (5).

  (7) The paper machine according to (6), wherein the liquid level control means includes a flow rate control valve provided in a pipe for supplying raw water to the inlet.

  (8) The raw water container is a vertically long cylindrical body having an inclined bottom surface, the inlet is provided in the vicinity of the lowermost end of the inclined bottom surface, and the uppermost end of the inclined bottom surface is lower than the detection level. The paper machine according to any one of (1) to (7), wherein the paper machine is level.

  (9) The liquid level control means includes a horizontal opening formed horizontally at the upper end of the raw water container so that raw water overflows. (1) to (8) The paper machine according to any one of the above.

  (10) The above (9) is characterized in that the raw water container is provided with a ring-shaped overflow collecting tray that surrounds the horizontal opening and collects the raw water overflowing from the horizontal opening. The paper machine described in 1.

  (11) A paper making method for making paper while removing bubbles by adding an antifoaming agent to the raw water, the raw water being continuously taken out from the main flow path of the raw water, and the main flow path In the middle of the bypass pipe to be returned, the defoamer addition amount is controlled based on the gas content measurement step for measuring the gas content of the raw water flowing through the bypass pipe and the measurement result by the gas content measurement device. An antifoaming agent adding step of adding an antifoaming agent to the main flow path, and the gas content measuring step has a higher level than the inlet of the raw water from the bypass pipe and the inlet A detection level higher than the inlet and lower than the outlet in the raw water container while controlling the liquid level of the raw water near the outlet in the raw water container provided with the outlet The hydraulic pressure at the Based on the sensor output of the sensor and the liquid level level information of the raw material water, the gas content of the raw water between the detection level of the hydraulic pressure sensor and the liquid level is calculated, and the defoaming is performed. In the agent addition step, the defoamer addition amount is controlled based on the calculated gas content of the raw material water.

  (12) The defoamer adding step is configured to control the defoamer addition amount so as to keep the gas content of the raw material water constant. Paper making method.

  (13) In the gas content measurement step, the raw water is taken into the bypass pipe from the vicinity of the downstream side of the circulation pump disposed in the circulation pipe of the paper-made white water that is a part of the main flow path. The paper making method according to (11) or (12) above, wherein

  (14) The main flow path is configured to include a drain pan for receiving paper-made white water from at least one of a wire part and a press part used for papermaking, and the gas content measurement step is a part of the main flow path. The papermaking method according to any one of (11) to (13), wherein the outlet of the bypass pipe is opened to return the raw water to the main flow path.

  (15) The paper making method according to (14), wherein the gas content measurement step is configured to open the outlet of the bypass pipe to the drain pan and return the raw water to the main flow path.

  (16) The gas content measuring step is characterized in that the liquid level is kept constant by controlling a flow rate of raw water flowing into the raw water container from the inlet. The paper making method according to any one of 11) to (15).

  (17) In the gas content measurement step, the flow rate of the raw material water flowing from the inflow port to the raw material water container is controlled using a flow rate control valve provided in a pipe for supplying the raw material water to the inflow port. The paper making method as described in (16) above, wherein

  (18) The gas content measurement step controls the liquid level of the raw material water in the vicinity of the outlet by overflowing the raw material water from a horizontal opening formed horizontally at the upper end of the raw material water container. The papermaking method according to any one of (11) to (15), wherein the papermaking method is performed.

  (19) The gas content measurement step is configured to collect the raw material water overflowing from the horizontal opening and return it to the main flow path with a ring-shaped overflow collecting tray surrounding the horizontal opening. The paper making method as described in (18) above.

  (20) The raw material water is continuously taken out from the main flow path, and the bypass pipe returning to the main flow path is disposed in the middle of the bypass pipe, and the gas content of the raw water flowing through the bypass pipe is contained. Defoaming agent addition by the defoaming agent pump based on the measurement result by the gas content measuring device for measuring the amount, the antifoaming agent pump for adding the antifoaming agent to the main flow path, and the gas content measuring device A control device for controlling the amount of the raw material, the gas content measuring device comprising a raw material water inlet from the bypass pipe and a raw material outlet provided at a higher level than the inlet A water container, a hydraulic pressure sensor that is higher than the inlet and lower than the outlet in the raw water container, and detects a hydraulic pressure at the detection level; Control the level of raw water A liquid level control means for controlling the liquid level from the detection level of the hydraulic pressure sensor based on the sensor output of the hydraulic pressure sensor and the liquid level level information of the raw water. An antifoaming agent addition system comprising an arithmetic unit that calculates a gas content of raw material water up to a surface level.

  (21) The control device is configured to control an antifoaming agent addition amount by the antifoaming agent pump so as to keep a gas content of raw material water constant. The paper machine described in 1.

  (22) A part of the main flow path is a circulation pipe for paper-made white water, and at least one circulation pump is disposed in the circulation pipe, and the bypass pipe is the circulation pump in the main flow path. The antifoaming agent addition system according to (20) or (21), wherein the antifoaming agent addition system according to the above (20) or (21) is connected to the downstream side.

  (23) The main flow path includes a drain pan for receiving paper-made white water from at least one of a wire part and a press part used for paper making, and an outlet of the bypass pipe opens to a part of the main flow path. The antifoaming agent addition system according to any one of (20) to (22), wherein the antifoaming agent addition system is provided.

  (24) The defoamer addition system according to (23), wherein an outlet of the bypass pipe is provided open to the drain pan.

  (25) The liquid level control means controls the flow rate of raw water flowing from the inlet to the raw water container so that the liquid level is constant. 20) The antifoamer addition system according to any one of (24).

  (26) The defoamer addition system according to (25), wherein the liquid level control means includes a flow rate control valve provided in a pipe for supplying raw water to the inflow port.

  (27) The raw water container is a vertically long cylindrical body having an inclined bottom surface, the inlet is provided in the vicinity of the lowermost end of the inclined bottom surface, and the uppermost end of the inclined bottom surface is lower than the detection level. The antifoaming agent addition system according to any one of (20) to (26), wherein the antifoaming agent addition system is characterized in that it is at a level.

  (28) The liquid level control means includes a horizontal opening horizontally formed at the upper end of the raw water container so that the raw water overflows. (20) to (27) The antifoamer addition system in any one of.

  (29) The (28), wherein the raw water container is provided with a ring-shaped overflow collecting tray that surrounds the horizontal opening and collects the raw water overflowing from the horizontal opening. Defoamer addition system as described in 1.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

  As shown in FIG. 1, a paper machine 2 according to an example of an embodiment of the present invention includes an antifoaming agent addition system 50 and is characterized by the antifoaming agent addition system 50. Since other configurations are the same as those of the conventional paper machine, the description will be omitted as appropriate.

  The defoamer addition system 50 is disposed in the middle of the bypass pipe 56 and a bypass pipe 56 for continuously taking out a part of the paper-made white water from the main flow path 54 and returning it to the main flow path 54. Measurement by the gas content measuring device 10 for measuring the gas content of the paper-made white water flowing through the pipe 56, the antifoaming agent pump 60 for adding an antifoaming agent to the main channel 54, and the measurement by the gas content measuring device 10 And a control device 62 for controlling the amount of antifoam added by the antifoam pump 60 based on the result. The “main flow channel” is used in the meaning including not only unused white water channels but also paper-made white water channels.

  The paper machine 2 includes a wire part 64 that performs paper making. Below the wire part 64, a drain pan 65 for collecting the paper-made white water and a paper-made white water tank 66 for storing the paper-made white water are provided. The paper-made white water tank 66 is connected to a circulation pipe 55 and a circulation pump 68 for sending the paper-made white water.

  The reference numeral 70 in the figure is a seed box for supplying unused white water, and the unused white water supplied from the seed box 70 is used as raw water together with the paper-made white water sent from the circulation pump 68. It has become.

  Moreover, the code | symbol 72 of a figure shows the press part for pressing the paper made with the wire part 64 with a roll, and squeezing out the water | moisture content contained in paper.

  Reference numeral 74 in the drawing is provided in the middle of the main flow path 54 on the downstream side of the seed box 70, and a decurator for vacuum degassing the raw water, and 76 feeds the raw water through the decurator 74 by pressure. A circulation pump 78, a screen for filtering the raw water, and an inlet (head box) 80 for rectifying the raw water and supplying it to the wire part 64, respectively.

  Reference numeral 72A denotes a drain pan for collecting the paper-made white water squeezed in the press part 72, and 72B denotes a couch pit for collecting the paper-made white water from the drain pan 72A. The paper-made white water in the couch pit 72B is returned to the paper-made white water tank 66.

  The bypass pipe 56 has an outlet 56 </ b> A at a position close to the downstream side of the seed box 70 on the downstream side of the circulation pump 68 in the main flow path 54. The return port 56B is opened to the drain pan 65 (a part of the main flow path 54) in the wire part 64.

  The antifoaming agent pump 60 is connected to the main channel 54 so as to supply the antifoaming agent to the vicinity of the downstream side of the outlet 56 </ b> A of the bypass pipe 56 in the main channel 54.

  Next, the gas content measuring apparatus 10 will be described in detail with reference to FIGS.

  The gas content measuring apparatus 10 includes a raw water container 16 having a raw water inlet 12 and an outlet 14 provided at a higher level than the inlet 12, and the inlet in the raw water container 16. The liquid level sensor 18 is provided at a detection level L higher than 12 and lower than the outlet 14, and detects the hydraulic pressure at the detection level L, and the liquid level of the raw water near the outlet 14. Based on the liquid level control means 20 for controlling the level Lh, the sensor output of the hydraulic pressure sensor 18 and the information on the liquid level Lh of the raw material water, the liquid level is detected from the detection level L of the hydraulic pressure sensor 18. And an arithmetic unit 22 for calculating the gas content of the raw water up to Lh. The arithmetic device 22 constitutes the control device 62 together with a shift control device 24A described later.

  In the middle of the bypass pipe 56, a manual valve 32, a flow meter 34, and a control valve 36 are arranged in this order from the main flow path 54 side.

  The raw water container 16 is a vertically long cylindrical body having an inclined bottom surface 38, the inlet 12 is provided in the vicinity of the lowermost end of the inclined bottom surface 38, and the uppermost end of the inclined bottom surface 38 is The level is lower than the detection level L of the hydraulic pressure sensor 18.

  Here, the inlet 12 and the bypass pipe 56 connected to the inlet 12 have a considerably small cross-sectional area (about 1/5 in diameter ratio) with respect to the cross-sectional area of the cylindrical raw material water container 16, thereby The raw water in the raw water container 16 is prevented from being disturbed by new fluid from the inlet 12.

  The outlet 14 at the upper end of the raw water container 16 is a horizontal opening formed horizontally so that the raw water overflows, and the shape of the outlet 14 and the flow rate of raw water flowing from the inlet 12 are determined. The liquid level control means 20 is constituted by the control valve 36 to be controlled.

  For example, if the opening degree of the control valve 36 is increased to increase the amount of raw material water flowing into the raw material water container 16, the liquid level Lh of the raw material water at the outlet 14 is increased. If the squeezing is performed, the liquid level Lh is lowered. Moreover, if a notch etc. are provided in the outflow port 14, the liquid level Lh will become low.

  Around the horizontal opening (outlet) 14 in the raw water container 16, a ring-shaped overflow collecting tray 40 for collecting raw water overflowing from the outlet 14 is provided.

  Further, as shown in FIG. 3, two collecting ports 42 are provided on the bottom surface of the overflow collecting plate 40, and the collecting pipe 30 is connected to the collecting port 42. The overflowing raw material water is guided to the return port 56 </ b> B by the recovery pipe 30 and returned to the drain pan 65.

  The arithmetic unit 22 constitutes a part of the control unit 62 and detects the hydraulic pressure detection value at the detection level L detected by the hydraulic pressure sensor 18 and the detection in a state where no gas is contained. The amount of gas contained in the raw material water above the detection level L based on the ratio or difference between the detected value based on the head pressure of the raw material water between the level L and the liquid level Lh Has been calculated.

  In this case, if the opening degree of the control valve 36 is set to be a predetermined liquid level Lh, the calculation is easy.

  When the amount of raw material water flowing into the raw material water container 16 is changed frequently, the opening signal of the control valve 36 or the flow rate signal from the flow meter 34 is input to the arithmetic unit 22 as one variable. The liquid level Lh may be calculated from the relationship with the inflow amount, and the gas content may be calculated based on this.

  In this gas content measuring apparatus 10, the gas content can be measured easily and reliably and continuously without changing the pressure of the raw material water to a high or low level or performing complicated calculations. .

  Therefore, based on the measured gas content, the defoaming agent addition amount by the defoaming agent pump 60 is controlled via the speed change control device 24A constituting a part of the control device 62, and the circulation line 54 Foaming can be suppressed by an optimal amount of antifoam. In order to improve the quality of the paper product, it is preferable that the control device 62 controls the antifoaming agent pump 60 so as to keep the bubble content in the raw material water constant.

  That is, as shown in the flowchart of FIG. 9, the gas content in the raw water is measured using the gas content measuring device 10 (S102), and the control device 62 is controlled by the antifoaming agent pump 60 based on the measurement result. By adding the antifoaming agent while controlling the addition amount (S104), it is possible to suppress the consumption of the antifoaming agent or to keep the gas content in the raw material water constant.

  In the example of the above-described embodiment, the antifoaming agent pump 60 is configured to supply the antifoaming agent to the vicinity of the downstream side of the outlet 56A of the bypass pipe 56 in the main channel 54. However, the portion for supplying the antifoaming agent in the main flow path may be appropriately selected according to circumstances such as the structure of the paper machine. For example, the antifoaming agent may be supplied to unused white water upstream of the seed box, paper-made white water in the paper-made tank, and paper-made white water in the drain pan below the wire part.

  In the example of the above embodiment, the outlet 56A of the bypass pipe 56 is disposed on the discharge side of the circulation pump 68 on the downstream side of the papermaking white water tank 66, but the present invention is not limited to this. Instead, any raw material water may be taken out from any position of the main flow path. However, when it is provided adjacent to the downstream side of the circulation pump, the raw material water can be easily taken out. Therefore, for example, as indicated by a two-dot chain line in FIG. A bypass pipe 57 having an outlet 57A may be provided adjacent to the discharge side.

  Further, in the case of a papermaking system, the antifoaming agent has four types, a water-soluble active agent type, a self-emulsifying type, an emulsion type, and an oil type, and any of them may be used. In the case of petroleum-based raw water, it is selected according to the properties of the raw water, such as a self-emulsifying type antifoaming agent.

  Further, in the gas content measuring apparatus 10, the outlet 14 as a part of the liquid level control means 20 is a horizontal opening. However, the present invention is not limited to this, and the liquid level is controlled. What is necessary is just to overflow the fluid while maintaining it constant.

  For example, a number of outflow holes may be formed at the same horizontal level in the vicinity of the upper end of the cylindrical raw material water container. However, as in the example of the present embodiment, the horizontal opening of the outlet 14 is simple and the manufacturing cost can be reduced.

  Moreover, although the said raw material water container 16 becomes a structure provided with the inclination bottom face 38, this invention is not limited to this, A horizontal bottom face may be sufficient.

  However, when the inclined bottom surface 38 is provided as in the example of this embodiment, there is an advantage that the necessary volume of the raw water container 16 can be reduced.

[Experimental Example 1]
First, as in the example of the above embodiment, while measuring the amount of bubbles in the raw material water, an amount of an antifoaming agent proportional to the amount of bubbles in the raw material water was added by automatic control for about 4 days (about 96 hours). Specifically, for white water sent to the wire part at a flow rate of about 6000 l / min in the same manner as described above, the addition amount per unit time is automatically controlled as shown by the line with the symbol A in FIG. "Somasolv K300 (antifoaming agent: manufactured by Somaru Corporation)" was added. The produced paper product had a width of about 3600 mm and a production speed of about 500 m / min.

  As indicated by the line labeled B in FIG. 5, the amount of bubbles in the raw material water was almost stable immediately after the start of the addition of the antifoaming agent, and the fluctuation range was small. In FIG. 6 (B), the maximum value of the amount of bubbles (volume%) in the raw material water for 4 days (with the addition of an antifoaming agent by automatic control) is a white rectangle, and the minimum value is a horizontal striped rectangle. The average value is indicated by a black rectangle, and the standard deviation is indicated by a vertical stripe rectangle.

  The average amount of antifoaming agent added per unit time was about 8.5 ml / min. The maximum amount of bubbles in the raw water was about 0.88%.

  Next, the addition amount per unit time is kept constant so that the maximum amount of bubbles in the raw material water is equivalent to the case of adding the antifoaming agent by the above automatic control, and the defoaming agent (Somasolv K300 ) Was added continuously for about 2 days (about 48 hours). The other conditions were the same as in the case of adding the antifoaming agent by the above automatic control.

  In order to make the maximum amount of bubbles in the raw material water equivalent to the case of adding the antifoaming agent by the above automatic control, the antifoaming agent is added as shown by the line with the symbol C in FIG. About 11 ml / min had to be added.

  Further, as indicated by the line with the symbol D in FIG. 5, the output voltage of the hydraulic pressure sensor 18 corresponding to the amount of bubbles in the raw material water was not stable and the fluctuation range was large. In FIG. 6A, the maximum value of the amount of bubbles (% by volume) in the raw water for two days (quantified addition of antifoaming agent) obtained by converting the output voltage of the hydraulic pressure sensor 18 is outlined. The minimum value is a horizontal stripe rectangle, the average value is a black rectangle, and the standard deviation is a vertical stripe rectangle.

  Based on the above, the amount of antifoaming agent required to keep the maximum amount of bubbles in the raw material water constant is an amount proportional to the amount of bubbles in the raw material water by automatic control while measuring the amount of bubbles in the raw material water. It can be seen that if the amount of the antifoaming agent is added, the amount of the antifoaming agent can be greatly reduced by about 23% compared to the case where the amount of addition per unit time is constant.

  In addition, as shown in comparison with FIGS. 6 (A) and 6 (B), when the amount of bubbles in the raw material water is measured and an antifoaming agent in an amount proportional to the amount of bubbles in the raw material water is added by automatic control. The amount of change in the amount of bubbles in the raw material water was greatly suppressed compared to the case where a fixed amount of antifoaming agent was continuously added.

[Experiment 2]
Compared to Example 1 above, first, an antifoaming agent is continuously added to the raw water for about three and a half days (about 84 hours) so that the amount of addition per unit time is constant regardless of the amount of bubbles in the raw water. did. Specifically, as shown by the line with the symbol E in FIG. 7, the antifoaming agent (Somasolv K300) was added while keeping the addition amount per unit time constant at about 9.1 ml / min. . The other conditions were the same as in Experimental Example 1 above.

  As indicated by the line with the symbol F in FIG. 7, the output voltage of the hydraulic pressure sensor 18 corresponding to the amount of bubbles in the raw material water was not stable and the fluctuation range was large. FIG. 8 (A) shows the maximum value of the amount of bubbles (volume%) in the raw water for 3 and a half days (added with a defoamer) obtained by converting the output voltage of the hydraulic pressure sensor 18. Is a white rectangle, a minimum value is a horizontal stripe rectangle, an average value is a black rectangle, and a standard deviation is a vertical stripe rectangle.

  Next, as in the above embodiment, while measuring the amount of bubbles in the raw material water, an amount of antifoaming agent proportional to the amount of bubbles in the raw material water was added by automatic control for about 3 days (about 72 hours). Specifically, the antifoaming agent was added by automatically controlling the addition amount per unit time as indicated by the line with the symbol G in FIG.

  As shown by the line with the symbol H in FIG. 7, the amount of bubbles in the raw material water is almost stable after about half a day (about 12 hours) from the start of the addition of the antifoaming agent, and the fluctuation range is It was small. In FIG. 8 (B), the maximum value of the amount of bubbles (volume%) in the raw material water for 3 days (with the addition of an antifoaming agent by automatic control) is a white rectangle, the minimum value is a horizontal stripe rectangle, The average value is indicated by a black rectangle, and the standard deviation is indicated by a vertical stripe rectangle.

  As shown in comparison with FIGS. 8A and 8B, when the amount of bubbles in the raw material water is measured and the amount of defoamer proportional to the amount of bubbles in the raw material water is added by automatic control, The amount of change in the amount of bubbles in the raw material water was significantly suppressed as compared with the case where the antifoaming agent was continuously added.

  In both cases of Experimental Examples 1 and 2, when the amount of bubbles in the raw material water was measured and an amount of antifoaming agent proportional to the amount of bubbles in the raw material water was added by automatic control, a fixed amount of antifoaming agent was continuously added. As compared with the case where it was added to the paper product, the variation in the length direction of the produced paper product was remarkably small, and the quality was good. More specifically, the basis weight variation was small, the number of defects was small, and the formation was good. This is presumably because the amount of fluctuation in the amount of bubbles in the raw material water was suppressed to a small level.

  The present invention can be used for papermaking, and can easily and continuously measure the gas content in raw water, and can add an optimal amount of antifoaming agent to fluid raw water. It has the effect.

The side view including the partial block diagram which shows typically the paper machine which concerns on the example of embodiment of this invention Front view including a partial block diagram showing a gas content measuring device of an antifoaming agent addition system provided in the paper machine Top view Side view The graph which shows the value of the output signal of the hydraulic pressure sensor corresponding to the addition amount per unit time of the defoamer and the amount of bubbles in the raw material water over time in Experimental Example 1 The graph which shows the standard deviation of the largest bubble volume in raw material water, the minimum bubble volume, the average bubble volume, and the bubble volume in the experiment example 1 The graph which shows the value of the output signal of the hydraulic pressure sensor corresponding to the addition amount per unit time of the defoamer and the amount of bubbles in the raw material water over time in Experimental Example 2 The graph which shows the standard deviation of the largest bubble amount in the raw material water, the minimum bubble amount, average bubble amount, and bubble amount in the example 2 of the experiment The flowchart which shows an example of the paper making method by the paper machine which concerns on the example of embodiment of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 ... Paper machine 10 ... Gas content measuring device 16 ... Raw material water container 50 ... Defoamer addition system 54 ... Main flow path 55 ... Circulation line 56 ... Bypass pipe 56A ... Outlet 56B ... Return port 60 ... Defoamer pump 62 ... Control device 64 ... Wire part 65 ... Drain pan 66 ... Paper-made white water tank 68, 76 ... Circulation pump S102 ... Gas content measurement process S104 ... Defoamer addition process

Claims (29)

A paper machine equipped with a defoaming agent addition system for removing bubbles by adding an antifoaming agent to raw water,
The defoamer addition system includes a bypass pipe that continuously takes out the raw water from the main flow path of the raw water and returns it to the main flow path, and is disposed in the middle of the bypass pipe and flows through the bypass pipe. Based on the measurement results of the gas content measuring device for measuring the gas content of the raw water, the antifoaming agent pump for adding the antifoaming agent to the main flow path, and the gas content measuring device, the antifoaming agent A control device for controlling the amount of antifoam added by the pump,
The gas content measuring device includes a raw water container provided with an inlet of raw water from the bypass pipe and an outlet provided at a higher level than the inlet, and more than the inlet of the raw water container. A liquid pressure sensor that is provided at a detection level that is high and lower than the outlet and detects the liquid pressure at this detection level, and a liquid level control means that controls the liquid level of the raw water near the outlet. And having
The control device calculates the gas content of the raw water from the detection level of the hydraulic pressure sensor to the liquid level based on the sensor output of the hydraulic pressure sensor and the liquid level level information of the raw water. A paper machine comprising an arithmetic unit for performing the processing.   2. The paper machine according to claim 1, wherein the control device is configured to control an antifoaming agent addition amount by the antifoaming agent pump so as to keep a gas content of the raw material water constant. .   3. The main flow path according to claim 1, wherein a part of the main flow path is a circulation pipe for paper-made white water, and at least one circulation pump is disposed in the circulation pipe, and the bypass pipe is connected to the main flow path. The paper machine is characterized in that it is connected close to the downstream side of the circulation pump.   4. The main flow path according to claim 1, wherein the main flow path includes a drain pan for receiving paper-made white water from at least one of a wire part and a press part used for paper making, and an outlet of the bypass pipe is the main flow. A paper machine characterized by being open to a part of the road.   5. The paper machine according to claim 4, wherein an outlet of the bypass pipe is provided open to the drain pan.   6. The liquid level control means according to claim 1, wherein the liquid level control means controls a flow rate of the raw water flowing from the inlet to the raw water container so that the liquid level is constant. A paper machine characterized by that.   7. The paper machine according to claim 6, wherein the liquid level control means includes a flow rate control valve provided in a pipe for supplying raw water to the inlet.   In any one of Claims 1 thru | or 7, The said raw material water container is a vertically long cylindrical body which has an inclined bottom face, The said inflow port is provided in the bottom end vicinity of the said inclined bottom face, The uppermost end of this inclined bottom face is A paper machine having a level lower than the detection level.   9. The papermaking according to claim 1, wherein the liquid level control means includes a horizontal opening formed horizontally at the upper end of the raw water container so that raw water overflows. Machine.   10. The paper machine according to claim 9, wherein the raw water container is provided with a ring-shaped overflow collecting tray that surrounds the horizontal opening and collects the raw water overflowing from the horizontal opening. . A paper making method for making paper while removing bubbles by adding an antifoaming agent to raw water,
A gas content measuring step for measuring the gas content of the raw water flowing through the bypass pipe in the middle of the bypass pipe for continuously taking out the raw water from the main flow path of the raw water and returning it to the main flow path. And an antifoaming agent adding step of adding an antifoaming agent to the main channel while controlling an antifoaming agent addition amount based on a measurement result by the gas content measuring device,
The gas content measuring step includes a raw water level in the vicinity of the outlet in a raw water container provided with a raw water inlet from the bypass pipe and an outlet provided at a higher level than the inlet. While controlling the level, the liquid pressure at the detection level higher than the inlet and lower than the outlet in the raw water container is detected, the sensor output of the hydraulic pressure sensor and the liquid level of the raw water Based on the information, the gas content of the raw material water between the detection level of the hydraulic pressure sensor and the liquid level is calculated,
In the paper making method, the defoaming agent adding step controls the defoaming agent addition amount based on the calculated gas content of the raw water.   12. The paper making method according to claim 11, wherein the defoamer adding step is configured to control the defoamer addition amount so as to keep the gas content of the raw material water constant.   The gas content measurement step according to claim 11, wherein the gas content measurement step starts from the vicinity of the downstream side of the circulation pump disposed in the circulation line of the paper-made white water, which is a part of the main flow path, to the bypass pipe. A paper making method characterized in that the paper is taken out.   In any one of Claims 11 thru | or 13, the said main flow path is set as the structure containing the drain pan for accepting the paper-made white water from at least one of the wire part used for papermaking, and a press part, The said gas content measuring process The papermaking method, wherein the outlet of the bypass pipe is opened in a part of the main flow path to return the raw water to the main flow path.   15. The papermaking method according to claim 14, wherein the gas content measurement step opens the outlet of the bypass pipe to the drain pan to return the raw water to the main flow path.   16. The gas content measuring step according to claim 11, wherein the liquid level is kept constant by controlling a flow rate of the raw water flowing into the raw water container from the inlet. A paper making method characterized by the above.   17. The gas content measurement step according to claim 16, wherein the flow rate of the raw material water flowing from the inflow port into the raw material water container is controlled using a flow rate control valve provided in a pipe for supplying the raw material water to the inflow port. A paper making method characterized by the above.   18. The raw material water in the vicinity of the outflow port according to claim 11, wherein the gas content measurement step causes the raw material water to overflow from a horizontal opening formed horizontally at the upper end of the raw material water container. A paper making method characterized in that the liquid level is controlled.   19. The gas content measurement step according to claim 18, wherein the gas content measuring step collects the raw water overflowing from the horizontal opening by a ring-shaped overflow collecting tray surrounding the horizontal opening and returns it to the main flow path. A paper making method characterized by the above. A raw material water is continuously taken out from the main flow path, and a bypass pipe returning to the main flow path is disposed, and a gas content of the raw water flowing through the bypass pipe is measured in the middle of the bypass pipe. Control the defoamer addition amount by the defoamer pump based on the measurement result by the gas content measurement device, the defoamer pump that adds the antifoam agent to the main flow path, and the gas content measurement device A control device,
The gas content measuring device includes a raw water container provided with an inlet of raw water from the bypass pipe and an outlet provided at a higher level than the inlet, and more than the inlet of the raw water container. A liquid pressure sensor that is provided at a detection level that is higher than the outlet and detects the liquid pressure at this detection level, and a liquid level control means that controls the liquid level of the raw water near the outlet. And having
The controller calculates the gas content of the raw water from the detection level of the hydraulic pressure sensor to the liquid level based on the sensor output of the hydraulic pressure sensor and the liquid level level information of the raw water. A defoaming agent addition system comprising an arithmetic unit for performing the above operation.   21. The paper machine according to claim 20, wherein the control device is configured to control a defoaming agent addition amount by the defoaming agent pump so as to keep a gas content of the raw material water constant. .   In Claim 20 or 21, a part of the main flow path is a circulation pipe of paper-made white water, and at least one circulation pump is disposed in the circulation pipe, and the bypass pipe is connected to the main flow path. An antifoaming agent addition system, wherein the antifoaming agent addition system is connected close to the downstream side of the circulation pump.   23. The main flow path according to claim 20, wherein the main flow path includes a drain pan for receiving paper-made white water from at least one of a wire part and a press part used for paper making, and an outlet of the bypass pipe is the main flow. An antifoaming agent addition system characterized by being provided open to a part of a road.   24. The defoamer addition system according to claim 23, wherein an outlet of the bypass pipe is provided open to the drain pan.   25. The liquid level control means according to claim 20, wherein the liquid level control means controls the flow rate of the raw water flowing from the inlet to the raw water container so that the liquid level is constant. A defoamer addition system characterized by that.   26. The defoamer addition system according to claim 25, wherein the liquid level control means includes a flow rate control valve provided in a pipe for supplying raw water to the inflow port.   27. The raw water container according to any one of claims 20 to 26, wherein the raw water container is a vertically long cylindrical body having an inclined bottom surface, the inflow port is provided in the vicinity of the lowermost end of the inclined bottom surface, and the uppermost end of the inclined bottom surface is A defoamer addition system characterized in that the level is lower than the detection level.   28. The consumption level according to any one of claims 20 to 27, wherein the liquid level control means includes a horizontal opening formed horizontally at the upper end of the raw water container so that raw water overflows. Foaming system.   29. The defoaming device according to claim 28, wherein the raw water container is provided with a ring-shaped overflow collecting tray that surrounds the horizontal opening and collects raw water overflowing from the horizontal opening. Agent addition system.

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