JP6572767B2 - Cleaning method and cleaning system for paper making tools - Google Patents

Description

  The present invention relates to a cleaning method and a cleaning system for a paper making tool used in a paper machine.

  Paper is generally manufactured through a papermaking process in which a stock prepared by dispersing raw pulp in water is sequentially processed by a wire part, a press part, and a dryer part of a paper machine. In the paper making process, a paper layer of wet paper is formed while removing most of the water from the stock in the wire part (while dehydrating), the wet paper is squeezed and further dehydrated in the felt part, and wet paper is used in the dryer part. The wet paper is dried using a drying roll or the like. The base paper obtained by drying the wet paper is wound up by a reel part.

  In the papermaking process, the heat energy necessary for drying can be reduced by efficiently performing dewatering of the wet paper, particularly the water extraction in the felt part. However, if the felt part felt is clogged, dewatering will be poor. In the case of poor dehydration, the amount of moisture brought into the dryer part increases, the heat energy required for drying increases, and the basic unit of drying deteriorates.

  One of the causes of felt clogging is that fibers and chemicals contained in the wet paper migrate to the felt when the moisture of the wet paper migrates to the felt. In order to prevent dirt due to these transitions from accumulating in the felt, the felt is generally washed by spraying water using a shower. A method of using high-pressure water or a method of using water added with chemicals for a washing shower has been studied (for example, Patent Document 1).

JP 2001-140186 A

  In recent years, waste paper pulp such as deinked pulp (DIP) has been widely used as a raw material for paper, and accordingly, the amount of pitch (resin content) in the raw material pulp has increased. The pitch tends to become dirty due to adhesion to paper making tools such as wires, felts, belts and canvases during paper making. For this reason, it is necessary to increase the frequency of cleaning the papermaking tool, which leads to a decrease in production efficiency. Also, petroleum-based detergents are generally used to clean the pitch, but when using petroleum-based detergents, safety and environmental measures are required, causing workability to deteriorate. Yes.

  An object of this invention is to provide the washing | cleaning method and washing | cleaning system which can wash | clean the papermaking tools like felt effectively.

  The present invention for solving the above-described problems has the following aspects.

  [1] A method for cleaning a papermaking tool, which includes generating a bubble in cleaning water to be ejected from a shower nozzle, and ejecting the cleaning water obtained by the bubble generating process from the shower nozzle And a shower step of spraying the paper making tool, wherein the bubbles have a median diameter D50 of 100 μm or less when measured by an image measurement method at a jet nozzle of the shower nozzle.

  [2] The method according to [1], wherein in the bubble generation step, bubbles are generated based on a gas-liquid shearing method.

  [3] The method according to [1] or [2], wherein the bubble generation step includes adding an interfacial cleaning agent to the cleaning water.

  [4] The surfactant includes an anionic surfactant, a cationic surfactant, an amphoteric surfactant, and a surfactant selected from the group consisting of nonionic surfactants. The method according to any one of [1] to [3].

  [5] The method according to any one of [1] to [4], wherein in the bubble generation step, the interfacial cleaning agent is added in an amount of 1 to 10,000 ppm with respect to the cleaning water.

  [6] The method according to any one of [1] to [5], wherein the papermaking tool is felt.

  [7] The method according to any one of [1] to [6], wherein, in the shower step, the washing water is sprayed on a side of the felt that contacts the paper.

  [8] The paper making tool is mounted on a paper machine, and in the bubble generating step, the washing water is ejected from the shower nozzle positioned upstream in the paper making direction from the suction unit of the paper machine. The method according to any one of [1] to [7], wherein the papermaking tool is sprayed.

  [9] A system for cleaning a papermaking tool, wherein a bubble is formed in a shower nozzle that ejects cleaning water sprayed on the papermaking tool, and in the cleaning water to be ejected from the shower nozzle upstream of the shower nozzle. A bubble generating device that generates bubbles in the cleaning water such that a median diameter D50 measured by an image measurement method at a jet nozzle of the shower nozzle is 100 μm or less. The shower nozzle ejects washing water that has passed through the bubble generating device.

  In the present invention, bubbles are generated in the washing water used for shower washing of the papermaking tool so that the median diameter D50 of the bubbles measured at the shower nozzle outlet is 100 μm or less. The bubbles thus generated are considered to contain a certain amount of so-called microbubbles having a particle size of 50 μm or less, preferably 10 μm to several tens of μm, depending on the particle size distribution. According to recent research, microbubbles are said to cause a phenomenon called so-called crushing that shrinks and breaks due to pressure over time. Although not wishing to be bound by theory, in the present invention, it is considered that the impact force due to the crushing of the microbubbles contained in the generated bubbles contributes to the removal of the stain on the papermaking tool. According to the present invention, an excellent cleaning effect can be achieved.

  Further, according to another aspect of the present invention, bubbles are generated in the washing water used for shower washing of a papermaking tool so that the median diameter D50 is 100 μm or less when measured at the outlet of the shower nozzle. In addition to the above, an interfacial cleaner is added. Although not wishing to be bound by theory, it is believed that the addition of an interfacial cleaner improves the amount and / or stability of bubbles and increases the number of microbubbles that can contribute to the removal of dirt. According to this aspect of the present invention, a further excellent cleaning effect can be achieved.

  Embodiments according to the present invention will be described below.

[Paper making tools]
As used herein, the “papermaking tool” is a papermaking process (of the paper manufacturing process, a paper material in which raw pulp is dispersed in water is spread by a papermaking machine to form a paper layer. In the process of producing a base paper by dehydrating and squeezing, heating and drying, it is a consumable used by being attached to a paper machine. Examples of papermaking tools include wires, felts, belts and canvases.

  The “wire” is a net-like tool used for forming a paper layer of wet paper by spreading a paper material in which raw pulp is dispersed in water. “Felt” is a tool used to dehydrate a wet paper web made of wire. A “belt” is a tool that is attached between the paper machine and the felt to increase the contact area between the felt and the wet paper and increase the efficiency of dewatering. The “canvas” is a tool used to transport wet paper in a process of heating and drying wet paper that has been dehydrated with felt.

[shower]
As used herein, “shower” refers to a device that functions to disperse and eject a fluid under pressure from a hole formed in a container. (Also referred to as a nozzle). “Shower nozzle” or “nozzle” refers to a pipe-like mechanical part used to determine the direction of fluid flow.

  Any shower used in the industry can be used in the present invention.

  The shower can be installed in any place as appropriate according to the position and shape of the papermaking tool to be cleaned. For example, when cleaning the felt, the shower can be placed either on the outside (the side of the surface that contacts the paper) or on the inside (the side of the surface opposite the surface that contacts the paper). The shower may be provided on either the upstream side or the downstream side in the paper making direction with respect to the suction unit of the paper machine involved in dewatering, or may be provided so as to correspond to the suction unit. From the viewpoint of dirt removal properties, the shower is preferably provided outside the felt, and is preferably provided upstream of the suction unit.

  The shower is not limited to a fixed type, and may be a handheld type.

  The nozzle diameter, the number, the installation interval, and the ejection pressure of the shower nozzle are not particularly limited, and can be appropriately set according to the intended effect. The nozzle diameter can be, for example, in the range of 0.3 to 8.0 mm. Moreover, about the installation space | interval of a shower nozzle, it can be the range of 20-1800 mm, for example. Moreover, the amount of water used for the shower can be, for example, in the range of 0.3 to 100.0 L / min per nozzle. Moreover, the pressure which ejects washing water from a shower nozzle can be 0.04-1.00 MPa, for example.

[Washing water]
As used herein, “washing water” is water used for washing. The water can be, for example, industrial water, ground water, tap water, and the like. In the present invention, an interfacial cleaning agent can be added to the cleaning water for the purpose of imparting a cleaning effect.

[Interface cleaner]
As used herein, an “interfacial detergent” is an agent that contains a “surfactant” and has a cleaning action (to remove dirt). "Surfactant" is a substance with a chemical structure that has a hydrophilic group and a hydrophobic group (lipophilic group) in one molecule. When dissolved in water, it is ionized to form an ion (a charged atom). Or anionic surfactants that become atomic groups), ionic surfactants such as cationic surfactants and amphoteric surfactants, and nonionic surfactants that do not turn into ions when dissolved in water.

  The “surfactant” that can be used in the present invention is selected from the group consisting of an anionic surfactant, a cationic surfactant, an amphoteric surfactant, and a nonionic surfactant as the “surfactant”. Surfactants may be included. The “interfacial detergent” that can be used in the present invention may contain a water-soluble polymer, a chelating agent, water and the like for the purpose of imparting stability in addition to the surfactant.

  Examples of the interfacial cleaning agent containing the surfactant include Pitchguard CA212 and Pitchguard CA242A manufactured by Mentec Co., Ltd., Maintenance Clean and On-press. These can be suitably used in the present invention.

  In the present invention, the interfacial cleaning agent is added to the cleaning water in a proportion of, for example, 1 ppm to 10,000 ppm, preferably 5 ppm to 500 ppm. The interfacial cleaner is preferably added to the cleaning water upstream of the bubble generator. By adding the interfacial cleaning agent, the surface tension of the cleaning water is lowered, and when bubbles are generated by the bubble generator, the bubbles are difficult to disappear and are stabilized. Further, the effect of increasing the amount of bubbles can be obtained. From the viewpoint of increasing the effect, it is preferable that the addition amount is somewhat large, but from the viewpoint of cost effectiveness, there is an upper limit to the addition amount of the interfacial cleaner.

[Bubble]
As used herein, a “bubble” is a gas bubble that occurs inside or on the surface of a liquid.

  In the present invention, bubbles are generated in the washing water ejected from the shower nozzle so that the median diameter D50 measured at the outlet of the shower nozzle is 100 μm or less. Here, the median diameter D50 is also referred to as 50% particle diameter, and in the distribution in which the bubble diameter is plotted on the horizontal axis and the number of bubbles (cumulative%) is plotted on the vertical axis, the number of bubbles is 50% in cumulative%. The particle size corresponding to

  According to the present invention, the above-mentioned bubbles having the median diameter D50 depend on the particle size distribution, but a certain amount of so-called microbubbles having a particle size of 50 μm or less, preferably 10 μm to several tens of μm. It is considered to be included. According to recent research, microbubbles shrink with pressure over time and break down into so-called micronanobubbles with a particle size of about several hundreds of nanometers to less than 10 μm, which is called so-called crushing. Although not wishing to be bound by theory, it is considered that the impact force caused by the crushing of the microbubbles contained in the generated bubbles contributes to the removal of dirt on the papermaking tool. According to the present invention using such bubbles, an excellent cleaning effect can be obtained.

[Bubble generation method and apparatus]
The bubble generation method applicable to the present invention is not particularly limited as long as the above-mentioned particle diameter can be obtained. “Ultrasonic method” for generating bubbles by shock waves or cavitation, gas (air) and liquid (water) "Swirl flow method" (also called gas-liquid shearing method) that generates bubbles of micro size (particle size of about 10 to several tens of micrometers) by shearing force at high speed, gas compressed in the liquid at once "Pressure dissolution method" that generates bubbles of micro-size or millimeter-size particle diameter by releasing, pressure is applied to the gas, and bubbles of micro-size or millimeter-size particle diameter are generated through the porous or orifice in the liquid The “micropore method” or the like can be used, and the swirling flow method (gas-liquid shearing method) is preferably used.

  The bubble generating device applicable to the present invention is not particularly limited as long as the above particle diameter can be obtained, and a known bubble generating device can be used. For example, as a device that can add air to wash water to be sent, it has a fluid introduction port and a discharge port for wash water as disclosed in Japanese Patent Laid-Open No. 2001-62269, and gas-liquid mixing inside A fluid stirrer provided with means can be used. Also, a fluid mixing device that promotes mixing and stirring by providing a plurality of protrusions on the peripheral wall surface of the tube and increasing cavitation in the fluid as disclosed in Japanese Patent Application Laid-Open No. 2000-354749 I'm going. These apparatuses are available from, for example, OHR Corporation. For example, OHR mixer MX-E10 type manufactured by OHR Corporation can be suitably used.

  The particle size and amount of the generated bubbles can be controlled by appropriately setting various parameters such as air pressure and flow rate relative to the pressure and flow rate of the washing water. For example, the ratio of the air flow rate (volume per hour) to the wash water is preferably in the range of 0.5-20%.

[Measurement method of bubble particle size]
In the present invention, the method used to measure the particle size (diameter) of bubbles is an image analysis method. More specifically, in the embodiment of the present invention, the water containing bubbles ejected from the shower nozzle is received in a container (volume: 5 L), and the water is received using a metering pump (DME48-3AR) manufactured by Grundfos, The particle size was measured by feeding into an image measuring device (Microtrac PartAn SI manufactured by Microtrack Bell Co., Ltd.) at a flow rate of 800 ml / min.

  The present invention will be specifically described below with reference to examples and comparative examples. However, the present invention is not limited to the embodiments.

[Example 1]
A paper stock (pulp slurry) in which 100% deinked pulp (DIP) is dispersed in water as a raw material pulp, using a suction breast former type paper machine, a target basis weight of 19 g / m ² at a speed of 1050 m / min. The operation for producing the base paper was continuously performed for a long time. When a paper hole was produced in the manufactured base paper due to dirt such as the adhesion of pitch to the felt, the operation was temporarily stopped and the felt was washed from the outside of the felt. After the washing, the operation was started again.

  For cleaning the felt, water in which bubbles were generated by a bubble generator based on a gas-liquid shearing method provided upstream of the shower nozzle was ejected from the shower nozzle and used as cleaning water. At this time, bubbles were generated so that the median diameter D50 of the bubbles when measured at the shower nozzle outlet was 100 μm or less. Specifically, 25 L / min of tap water is treated with an OHR mixer MX-E10 type manufactured by OHR Co., Ltd. at an air mixing rate of 5%, and the water is injected into 225 L / min of shower water. Then, bubbles were generated by ejecting from the shower nozzle. The image analysis method described above was used for the measurement of the bubble particle size.

[Example 2]
The same as in Example 1 except that an interfacial cleaning agent (Pitchguard CA212 manufactured by Mentec Co., Ltd.) was added to the cleaning water to be ejected from the shower nozzle in an amount that would result in an addition concentration of 25 ppm with respect to the cleaning water. The operation for producing the base paper was performed using the conditions described above.

[Example 3]
The same as in Example 1 except that an interfacial cleaning agent (Pitchguard CA212 manufactured by Mentec Co., Ltd.) was added to the cleaning water to be ejected from the shower nozzle in an amount that would add 100 ppm to the cleaning water. The operation for producing the base paper was performed using the conditions described above.

[Comparative Example 1]
An operation for producing a base paper was performed using the same conditions as in Example 1 except that the step of generating bubbles with water using a bubble generator was not included.

<Test content and results>
(Test 1) Felt cleaning frequency When the 24-hour operation of the base paper was continuously performed for 30 days, the number of times that the operation was interrupted due to the necessity of cleaning the felt was measured. The smaller the number of times, the less frequent the cleaning should be and the higher the cleaning effect.

  In Examples 1 to 3, the number of felt washings required per 30 days was less than that in Comparative Example 1. In addition, Example 2 and Example 3 to which the interfacial cleaner was added had fewer felt washings required per 30 days than Example 1 to which no interfacial cleaner was added. According to the present invention, it is possible to reduce the frequency of cleaning papermaking tools in a papermaking machine.

(Test 2) Effect of addition of interfacial cleaning agent The effect of adding an interfacial cleaning agent to the cleaning water containing bubbles according to the present invention was confirmed.

(Test 2-1) Amount of bubbles [Example 4]
In the water to which no interfacial cleaning agent is added, bubbles are generated using the bubble generation device (OHR mixer MX-E10 type manufactured by OHR Corporation) used in Examples 1 to 3 above. Example 4 was made by receiving the water tank directly at the outlet of the bubble generating device without passing through the shower nozzle or other pipes.

[Example 5]
Example 5 and Example 5 were the same as Example 4 except that water containing a nonionic surfactant in an amount of 1000 ppm was used instead of water to which no interfacial detergent was added. did.

  About Example 4 and 5, the quantity of the bubble immediately after receiving in a water tank was measured as the transmittance | permeability (permeation | transmission distance, unit cm) using a laser pointer, and the value was compared. It shows that there are so many amounts of bubbles that the value of permeability is small.

In Example 5 to which the interfacial cleaner was added, the amount of generated bubbles was larger than in Example 4 to which no interfacial cleaner was added.
(Test 2-2) Heat source unit As an index of energy required for heating and drying wet paper in the base paper manufacturing process, 24-hour operation of base paper was continuously performed for 120 days. The amount of natural gas required (Nm ³ / t) was recorded and compared. Specifically, the amount of natural gas required in Example 1 the amount of natural gas required in Example 2 in the case of the (Nm ³ / t) based on the (Nm ³ / t) percentages (%) I asked for it. The smaller the percentage (%), the smaller the heat intensity, indicating that cleaning was performed effectively.

  In Example 2 in which the interfacial cleaner was added, the heat unit was smaller than in Example 1 in which no interfacial cleaner was added.

  ADVANTAGE OF THE INVENTION According to this invention, the washing | cleaning of the paper making tool used with the paper machine in the paper industry can be performed effectively. Therefore, it is possible to reduce the frequency of maintenance for cleaning a papermaking tool such as felt during a long operation. Further, during the long-time operation, the decrease in the water-squeezing performance in the felt is reduced, and as a result, the heat intensity for heating and drying is improved.

Claims (9)

A bubble generation step for generating a bubble in washing water which Ru is ejected from the sheet Yawanozuru,
A shower process of spraying the washing water obtained by the bubble generation process from the shower nozzle and spraying it on a papermaking tool;
Including
The method for cleaning a papermaking tool, wherein the bubbles have a median diameter D50 of 100 μm or less when measured by an image measurement method at a jet nozzle of the shower nozzle. The bubble in the generation step, papermaking equipment cleaning method according to claim 1, wherein the generating the bubble based on a gas-liquid shear methods. The method for cleaning a papermaking tool according to claim 1 or 2, wherein the bubble generation step includes adding an interfacial cleaning agent to the cleaning water. The method for cleaning a papermaking tool according to any one of claims 1 to 3, wherein in the bubble generation step, an interfacial cleaning agent is added in an amount of 1 to 10,000 ppm with respect to the cleaning water. 5. The surfactant according to claim 3, wherein the surfactant includes a surfactant selected from the group consisting of an anionic surfactant, a cationic surfactant, an amphoteric surfactant, and a nonionic surfactant. A method for cleaning a papermaking tool as described in 1. The method for cleaning a papermaking tool according to any one of claims 1 to 5, wherein the papermaking tool is a felt. 7. The method for cleaning a papermaking tool according to claim 6, wherein in the showering step, the cleaning water is sprayed on a side of the felt that contacts the paper . The paper making tool is mounted on a paper machine,
8. The bubble generation step, wherein the washing water is ejected from the shower nozzle positioned upstream in the paper making direction from the suction unit of the paper machine and sprayed onto the paper making tool. The method for cleaning a papermaking tool according to any one of the above. A shower nozzle for injecting the cleaning water blown onto the papermaking equipment,
Upstream of the shower nozzle, the cleaning water that will be ejected from the shower nozzle, a bubble generator for generating bubbles,
With
Said bubble generating device, the so shower median diameter D50 when measured by the image measuring method in the spout of the nozzle is 100μm or less, to generate the bubbles in the wash water,
The shower nozzle, papermaking equipment cleaning system, characterized in that for ejecting the washing water passed through the air bubble generating device.