JP2005065541A - Liquid filtration apparatus and method for producing clarified sugar solution - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simplify the structure of a liquid filtration apparatus and prevent the lowering in the recovery of an objective substance such as sugar. <P>SOLUTION: A membrane separation means as the first stage is connected to a concentrated solution-circulating means and a means for supplying a solution to be treated. The means for supplying the solution to be treated is provided with a solution-adding mechanism for supplying a dilution liquid for diafiltration. Thus, not only the undiluted solution but also the dilution liquid are supplied to the membrane separation means. Thereby, an ordinary filtration treatment for filtering the undiluted solution as such and the diafiltration for diluting the undiluted solution and simultaneously filtering the diluted solution can be carried out with the membrane separation means, and even when the apparatus is simplified, the lowering in the recovery of the objective substance can be prevented. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a liquid filtration device that separates impurities from a liquid and obtains a clear liquid, and more particularly, a sugar solution filtration device that separates impurities from a sugar solution containing impurities to obtain a clarified sugar solution and a clarified sugar solution. It relates to the production method.

  Sugar solution such as glucose solution obtained by liquefying starch or the like contains about 0.1 to 0.5% by weight of impurities such as fatty acids and proteins as insoluble suspended solids (SS). For this reason, these impurities are separated from the sugar solution, and the clarified sugar solution is recovered.

  As a method for separating impurities from a sugar solution, there is a diatomaceous earth filtration method in which a sugar solution is filtered using a vacuum filter pre-coated with a filter aid such as diatomaceous earth. However, in this method, there is a problem that a large amount of waste in which the filtration residue and the filter aid are mixed is generated along with the filtration, and the filtration residue cannot be reused as feed.

  Therefore, as a filtration method that does not use a filter aid, a membrane filtration method using an ultrafiltration (UF) membrane or a microfiltration (MF) membrane is used. For example, Japanese Patent Laid-Open No. 2002-112800 (Patent Document 1) includes first to third three-stage membrane separation means having different effective membrane areas, and the third membrane separation means has a diafiltration filtration. A starch saccharified solution refining device provided with a washing solution adding means for performing (a filtration method of filtering while adding a solvent such as water to a stock solution) is disclosed.

  In this starch saccharified liquid purification apparatus, concentrated saccharified liquid from which SS has been removed is recovered by performing concentrated separation of SS in the stock solution by the first and second membrane separation means, and concentrated liquid in which SS is concentrated. Is filtered by diafiltration by a third membrane separation means, and glucose remaining in the concentrate is recovered. In this starch saccharified solution purification device, glucose can be efficiently recovered from the starch saccharified solution, and the device can be miniaturized. In addition, a large amount of waste containing diatomaceous earth is not generated.

By the way, since the above apparatus is provided with a plurality of stages of membrane separation means, the apparatus configuration becomes large and cannot be installed in a narrow space. On the other hand, if the membrane separation means is a single stage, efficient concentration cannot be performed, and the recovery rate of the target substance decreases.
JP 2002-112800 A

  The present invention has been made in view of the problems as described above, and the object thereof is a liquid capable of realizing a space saving with a simple apparatus configuration without reducing the recovery rate of a target substance such as sugar. An object of the present invention is to provide a filtration device and a method for producing a clarified sugar solution.

  In the present invention, the membrane separation means is in one stage, and membrane filtration is performed while circulating the liquid to be treated through the membrane separation means. When SS in the liquid to be treated has been concentrated, a diluting liquid is appropriately supplied to the membrane separation means in which the concentrated liquid in which SS is concentrated circulates, so that Filtration filtration is performed to sufficiently recover the target substance such as sugar remaining in the concentrate. Thereafter, the membrane separation means was washed, and the membrane separation means was continuously used until it could not be reused. In particular, in the present invention, diafiltration filtration is performed when the SS concentration of the liquid to be processed including the circulated concentrated liquid is concentrated to the concentration limit.

  More specifically, the present invention provides the following.

  (1) Membrane separation means having a structure partitioned into a liquid to be treated side and a permeate side through a permeable membrane that separates impurities in the liquid to be treated, and the liquid to be treated side of the membrane separation means A treatment liquid supply means for supplying a treatment liquid and a concentrated liquid that is connected to the membrane separation means and in which impurities in the treatment liquid are concentrated by the membrane separation means is discharged from the treatment liquid side of the membrane separation means. And a concentrated liquid circulating means for circulating the discharged concentrated liquid to the treated liquid side of the membrane separation means, wherein the treated liquid supply means is the concentrated liquid circulating means. For supplying a liquid to be treated to the membrane separation means through the concentrate circulation means and for diafiltration filtration for the membrane separation means Liquid filtration having a liquid addition mechanism for supplying liquid Location.

  (2) Concentration limit detection means for detecting that the liquid to be treated containing the circulated concentrated liquid has been concentrated to the concentration limit, and when the concentration limit is detected by the concentration limit detection means, The liquid filtration apparatus according to (1), wherein a dilution liquid is supplied from the treatment liquid supply means, and diafiltration filtration is performed by the membrane separation means.

  (3) The liquid filtration device according to (1) or (2), wherein the liquid filtration device is a sugar solution filtration device that obtains a clarified sugar solution from which impurities are removed by filtering a sugar solution containing impurities.

  (4) Removing impurities in the sugar solution containing impurities using a membrane separation means having a structure partitioned into a liquid to be treated side and a permeate side through a permeable membrane that separates impurities in the liquid to be treated. A clarified sugar solution producing method for obtaining a clarified sugar solution, wherein the solution to be treated is circulated on the treatment solution side of the membrane separation means while the treatment solution is pressurized and supplied to the treatment solution side. In this state, the liquid to be treated is separated into a clarified sugar liquid and a concentrated liquid to obtain a clarified sugar liquid, and after the raw liquid filtration process has progressed, the liquid to be treated is circulated. A diafiltration step of further filtering the clarified sugar solution from the concentrated solution, and a method for producing a clarified sugar solution.

  (5) The method for producing a clarified sugar liquid according to (4), wherein the diafiltration filtration step is performed when the liquid to be treated reaches a concentration limit.

  Examples of the liquid processed by the liquid filtration device of the present invention include a liquid in which other substances are contained as impurities in a liquid in which a target substance such as sugar, amino acid, or enzyme is dissolved. The liquid filtration apparatus of the present invention obtains a solution of the target substance from which impurities have been removed by separating the impurities in the stock solution composed of such liquids. The liquid filtration device of the present invention is particularly preferably a sugar solution filtration device that produces a clarified sugar solution from which impurities are removed by filtering a sugar solution containing impurities.

  Here, the “sugar solution containing impurities” as used herein is a liquid in which saccharides such as glucose and sucrose are dissolved, and impurities such as fatty acids, proteins, and fibers other than saccharides are set to 0. It means a liquid containing about 1 to 0.5% by weight. Examples of the sugar solution containing impurities to be processed by the sugar solution filtering device of the present invention include sugarcane juice, sugar beet sugar extract, glucose solution obtained by liquefying and saccharifying starch such as corn starch with an enzyme, and the like. . The sugar solution containing impurities usually has a viscosity of about 0.7 to 1.2 cp and is filtered in a state heated to 60 to 80 ° C. On the other hand, the “clarified sugar solution” is a sugar solution obtained by separating impurities from a sugar solution containing impurities, and does not substantially contain SS.

  The “liquid to be treated” refers to a liquid to be filtered by the liquid filtration apparatus of the present invention, specifically, a stock solution containing impurities before the filtration process, and a liquid discharged from the liquid to be treated side of the membrane separation means. And SS-concentrated liquid (referred to as “concentrated liquid”), diluting liquid supplied for diafiltration and mixtures thereof. That is, the treatment liquid supply means of the present invention supplies not only a stock solution such as a sugar solution containing impurities as a treatment liquid but also a dilution liquid for diafiltration filtration. By supplying both the undiluted solution and the diluting solution with the liquid to be treated, the apparatus can be simplified and the recovery rate of the target substance can be prevented from being lowered.

  The “permeation membrane” provided in the membrane separation means is a membrane that allows permeation of a target substance such as saccharide dissolved in the stock solution but does not permeate insoluble SS as an impurity. Accordingly, “impurities” refer to all substances that are larger than the target substance such as sugar molecules dissolved in the liquid and do not permeate the permeable membrane, and mainly mean SS that is an insoluble suspended substance. Specific examples of the permeable membrane include a UF membrane having a molecular weight cut-off of 10,000 or more, preferably 50,000 or more, or an MF membrane having a pore diameter of about 0.01 to 10 μm, preferably about 0.05 to 0.5 μm. .

  The liquid filtration device of the present invention is preferably provided with a concentration limit detection means for detecting that the liquid to be treated has been concentrated to the concentration limit. By providing a concentration limit detection means, it is possible to increase the concentration ratio to the concentration limit and collect the target substance such as sugar in the stock solution, and then perform diafiltration filtration of the concentrated liquid concentrated at a high magnification. Therefore, the time required for diafiltration can be reduced by reducing the amount of the diafiltration target liquid.

  In the present invention, since the membrane separation means conventionally provided in multiple stages is made into a single stage, the apparatus is not complicated, can be installed in a narrow space, and the installation and maintenance of the apparatus are easy. Become. In the present invention, a concentrated liquid circulating means for circulating the concentrated liquid to the membrane separation means is provided, and the liquid to be treated is supplied not only to the stock solution but also to the dilution liquid. For this reason, it is possible to perform a normal filtration process that filters the undiluted solution without diluting, and a diafiltration filtration that filters while diluting the highly concentrated concentrate with a single membrane separation means. The target substance can be efficiently recovered with the apparatus thus constructed. That is, in the present invention, a single membrane separation means highly concentrates the stock solution to continuously obtain a clear liquid, and collects the target substance remaining in the concentrated solution concentrated at a high magnification. Therefore, even if the membrane separation means is a single stage, it is possible to prevent the recovery rate of the target substance such as sugar from decreasing.

  Furthermore, the present invention provides a concentration limit detecting means for detecting that the SS concentration in the liquid to be treated has reached the concentration limit value. For this reason, it is possible to perform an efficient operation of the apparatus that highly concentrates the stock solution and shortens the time required for diafiltration while preventing clogging of the membrane.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic view showing a sugar liquid filtration device according to an embodiment of the present invention. In the following description, the same reference numerals are given to the same components.

  In FIG. 1, the sugar liquid filtration device 1 includes a membrane separation means 20, a liquid to be treated supply means 10, and a concentrate circulation means 30. The concentrated liquid circulation means 30 is connected to the membrane separation means 20 and the treatment liquid supply means 10 and supplies the treatment liquid from the treatment liquid supply means 10 to the membrane separation means 20.

  The treatment liquid supply means 10 is a means for supplying the treatment liquid to the membrane separation means 20, and the inlet pressure of the membrane separation means 20 is 0.1 to 0.8 Mpa, preferably 0.2 to 0.6 Mpa, and the outlet. The liquid to be treated is pressurized and supplied to the membrane separation means 20 so that the pressure is about 0.0 to 0.4 MPa. The processing liquid supply means 10 includes a storage tank 12 for storing a predetermined amount of processing liquid, a processing liquid pipe 13 through which the processing liquid passes, and a pump 14 that sends the processing liquid to the membrane separation means 20. The stock tank 11 and a liquid adding mechanism 50 described later are connected to the storage tank 12, and a liquid level gauge 82 is provided inside. Further, the stock solution pipe 11 is provided with a flow meter 81, and in this embodiment, the flow meter 81 and the liquid level meter 82 cooperate to detect that the liquid to be treated has been concentrated to the concentration limit.

  The liquid tube 13 to be treated is connected to the storage tank 12 and the concentrated liquid circulation means 30. A pump 14 is provided in the middle of the liquid pipe 13 to be processed. The liquid to be treated is taken out from the storage tank 12, pressurized to a predetermined pressure by the pump 14 and the circulation pump 32 via the liquid pipe 13 to be treated, and supplied to the membrane separation means 20 via the concentrated liquid circulation means 30. To do. The configuration of the processing liquid supply unit 10 is not limited to that described above, and can be configured by any member that can pressurize the processing liquid and supply it to the membrane separation unit 20. For example, the liquid to be treated is used without using the pump 14 by using the difference in altitude between the storage tank 12 and the membrane separation means 20 or increasing the pressure of the liquid in the storage tank 12 by pressurizing the storage tank 12. It can also be configured to be sent out to the membrane separation means 20.

  In the present invention, the to-be-processed liquid supply means 10 supplies not only the raw solution before the filtration process but also the diluting liquid for diafiltration filtration to the membrane separation means 20. In this embodiment, the to-be-processed liquid supply means 10 supplies the liquid for dilution to the membrane separation means 20 by providing the liquid addition mechanism 50 in particular. The liquid addition mechanism 50 is a means for supplying a diluting liquid for diluting a concentrated liquid as a stock solution when diafiltration is performed. The liquid addition mechanism 50 includes at least a dilution liquid pipe 51 through which the dilution liquid passes. The dilution liquid pipe 51 may include a dilution liquid flow meter 52 for measuring the supply amount of the dilution liquid, a safety filter, a flow rate adjustment valve (not shown), and the like as necessary. In the present embodiment, the liquid addition mechanism 50 is configured to dilute the concentrate in the storage tank 12 by connecting the dilution liquid pipe 51 to the storage tank 12. However, the dilution liquid pipe 51 is connected to the raw liquid pipe 11 and a flow path switching valve or the like is provided in the raw liquid pipe 11 so that the dilution liquid passes through at least a part of the raw liquid pipe 11 and enters the storage tank 12. It can also be configured.

  The membrane separation means 20 has a structure in which a space is partitioned into a liquid to be processed side and a permeate side through a permeable membrane that separates impurities in the liquid. An example of membrane separation means having such a structure is a membrane module 21 having a permeable membrane of any shape in a housing (housing) made of any material such as metal or resin. As a form of the membrane module, any form such as a hollow fiber type, a spiral type, and a flat membrane type can be used. A tubular membrane module including a plurality of tubular membranes is capable of highly concentrating SS, which is an impurity, and can be suitably used.

  As the permeable membrane, in the case of this embodiment using a sugar solution containing impurities as a stock solution, any organic membrane or inorganic membrane can be used regardless of the material as long as it is a membrane that allows saccharides to permeate but not SS. be able to. However, since inorganic films such as ceramic films and sintered metal films have high chemical and physical strength and can obtain a concentration ratio as high as 50 times, the viscosity in a state heated to 60 to 80 ° C. The stock solution is suitable for sugar solution filtration in which the membrane separation means 20 is supplied. In particular, a sintered metal film in which a thin filtration layer is formed by further sintering and coating a dissimilar metal such as titanium oxide on a sintered surface obtained by sintering stainless steel particles is preferable because of high filtration efficiency and strength. The membrane filtration method is preferably a cross flow method. In the cross-flow filtration, since the concentrated liquid flows in a direction perpendicular to the permeated liquid, it is possible to prevent sludge (sludge in which impurities are concentrated) from accumulating on the membrane surface and reducing the filtration efficiency. As such a membrane separation means, a sintered metal membrane tube having an inner diameter of 5 to 25 mm, preferably 8 to 22 mm, is incorporated in a metal cylindrical housing in a length of 1.5 to 12 m. Preferably, a tubular metal membrane module of about 3 to 6 m is suitable.

  In the present embodiment, the membrane separation means 20 includes a membrane module 21 provided with a tubular sintered metal membrane having a diameter of 19 mm and a hole diameter of 0.1 μm in a metal cylindrical housing. The membrane module 21 includes a clarified sugar solution pipe 61 that discharges the clarified sugar solution from the permeate side of the membrane module 21, an air vent tube 71 that discharges air in the membrane module 21, and a liquid to be treated in the membrane module 21. A mixed liquid pipe 33 to be introduced into is connected. The clarified sugar liquid tube 61 constitutes a clarified sugar liquid recovery mechanism 60, and may include a constant flow valve 62, a flow meter 63, and the like as required as shown in FIG. The air bleed pipe 71 includes an air bleed valve 72 for opening the air bleed pipe 71 and discharging the air in the membrane module 21 during air bleed, and constitutes an air bleed mechanism 70.

  An example of the membrane module 21 is shown in FIG. FIG. 2 shows a cross-flow membrane module 21 including a main body 200, a lower liquid chamber 201, and an upper liquid chamber 202. Both the lower liquid chamber 201 and the upper liquid chamber 202 of the membrane module 21 are connected to the main body 200 by a flange 205. The main body 200 is provided with an opening 206 for taking out the clarified sugar liquid, and the clarified sugar liquid pipe 61 is connected to the opening 206. A tube 210 made of a plurality of hollow permeable membranes is built in the main body 200.

  As shown in FIG. 2, the space inside the main body 200 of the membrane module 21 is a liquid side m (part drawn with a broken line) and a permeate side n (part where no broken line is drawn) with the membrane surface of the tube 210 as a boundary. ). Further, a partition plate 220 is provided inside the main body 200, and is partitioned into an upward flow filtration chamber 221 and a downward flow filtration chamber 222. The lower liquid chamber 201 is divided into a liquid chamber 203 and a concentrated liquid chamber 204 by a partition plate 230. The upper liquid chamber 202 is provided with a rectifying plate 240 for preventing the backflow of the liquid to be processed as necessary.

  The liquid to be processed is introduced from the mixed liquid pipe 33 into the liquid chamber 203 to be processed in the membrane module 21 and moved in the upward flow (in the direction of arrow a) through the tube 210 provided in the upward flow filtration chamber 221. . The tube 210 is made of a membrane that allows sugar molecules dissolved in the liquid to be treated to pass through, but does not allow SS to pass through. For this reason, by flowing the liquid to be processed into the tube 210, the clarified sugar liquid from which SS has been separated moves in a direction perpendicular to the flow of the liquid to be processed (the direction of the arrow b). It is poured out to the permeate side n. In addition, the concentrated liquid in which SS is concentrated remains in the liquid to be processed m, enters the liquid chamber 203 to be processed into the upper liquid chamber 202 (in the direction indicated by arrows a to c), and enters the downflow filtration chamber 222. After moving in the tube 210 in a downward flow (in the direction of the arrow d) and entering the concentrate chamber 204, the concentrate is discharged out of the membrane module 21 through the concentrate pipe 31. At this time, also in the downward flow filtration chamber 222, the concentrated liquid as the liquid to be treated is subjected to membrane filtration in a cross-flow manner, and the clarified sugar liquid from which SS has been separated is removed from the permeate side n (indicated by the arrow e). Direction).

  Next, the concentrated liquid circulating means 30 of the sugar liquid filtration device 1 will be described with reference to FIG. The concentrated liquid circulation means 30 is a means for discharging the concentrated liquid, in which SS, which is an impurity in the liquid to be processed, is concentrated by the membrane separating means 20 from the liquid to be processed of the membrane separating means 20, and It is a means for circulating to return to the treatment liquid side. The concentrated liquid circulation means 30 includes a pipe that forms a circulation path outside the membrane separation means 20. As the pipe, a pipe made of metal, resin, or the like can be suitably used, and the volume of the pipe is preferably set as appropriate according to the volume of the membrane separation means 20, the circulation amount of the concentrate, and the like. By adjusting the volume of the piping according to the volume of the membrane separation means 20 and the like, the flow rate of the liquid to be treated in the membrane separation means 20 and the flow rate of the liquid in the concentrated liquid circulation means 30 are adjusted, and sludge in the apparatus is adjusted. Can be prevented. Further, the liquid supply means 10 is connected to the pipe, and the liquid supplied from the storage tank 12 is mixed with the concentrated liquid. Since the liquid supplied from the storage tank 12 has a lower SS concentration than the liquid circulating in the concentrated liquid circulating means 30, the SS concentration of the liquid to be processed supplied to the membrane separating means 20 is kept to a certain degree of dilution. Can do.

  In the present embodiment, the concentrated liquid circulating means 30 includes a concentrated liquid pipe 31 that discharges the concentrated liquid from the membrane separating means 20, a circulating pump 32 that circulates the concentrated liquid, and the concentrated liquid on the treated liquid side of the membrane separating means 20. A liquid mixture pipe 33 is provided. The concentrated liquid pipe 31 and the mixed liquid pipe 33 are connected via a circulation pump 32 and form a circulation path outside the membrane separation means 20. A concentrated liquid pipe 31 is connected to the suction side of the circulation pump 32, and a mixed liquid pipe 33 is connected to the discharge side of the circulation pump 32. Further, the liquid pipe 13 is connected to the concentrated liquid pipe 31, and the liquid to be processed supplied from the storage tank 12 is mixed with the concentrated liquid to pass through a part of the concentrated liquid pipe 31 and the mixed liquid pipe 33. It is supplied to the membrane separation means 20. Further, in the concentrated liquid pipe 31 in front (upstream side) of the connection point with the liquid pipe 13 to be processed, a return mechanism 90 for returning a part of the concentrated liquid to the storage tank 12 and for discharging the filtration residue outside the apparatus. A discharge mechanism 40 is connected. The return mechanism 90 includes a return pipe 91 connected to the concentrate pipe 31 and the storage tank 12. A part of the concentrate in the concentrate circulating means 30 is returned to the storage tank 12 by the return pipe 91. Further, the return pipe 91 is provided with a pressure adjusting valve 92 for adjusting the circulation flow rate of the concentrate. In the present embodiment, the pressure regulating valve 92 cooperates with the valve 62 provided in the clarified sugar liquid pipe 61 to keep the pressure of the liquid to be treated constant and collect the clarified sugar liquid at a constant flow rate. Used for.

  Concentration limit detection means means that the liquid to be treated, which is a mixture of the concentrate and the undiluted solution, is circulated through the membrane filtration device a plurality of times and processed, so that SS in the liquid to be treated is concentrated and the liquid to be treated is It is a means for detecting that the concentration limit has been reached. Specific examples of the concentration limit detecting means include a flow meter, a liquid level meter, a turbidity meter, and a pressure gauge. The concentration limit means that it is not preferable to concentrate the liquid to be processed at a higher magnification. The concentration limit of the liquid to be treated varies depending on the membrane separation means used, but the concentration ratio is 5 to 50 times, preferably about 10 to 20 times, and the SS concentration in the mixed solution is 1 to 10% by weight, preferably 2 It is a point which becomes -4 weight%. In the present embodiment, a flow meter 81 is provided in the stock solution pipe 11 as a concentration limit detection means, and a liquid level meter 82 is provided in the storage tank 12. Then, the amount of the concentrated solution is a predetermined value of 1/5 to 1/50 of the stock solution supply amount obtained from the flow meter 81 (for example, 1/20 when the concentration limit is 20 times the concentration limit). The time point is detected by the liquid level gauge 82. Further, the fact that the liquid to be processed has reached the concentration limit can be detected by providing a turbidimeter in the storage tank 12 or the like. Furthermore, the time when the concentration limit is reached can also be detected by measuring the membrane pressure of the membrane separation means 20 or measuring the flow rate of the clarified sugar solution using the flow meter 63.

  Next, a method for producing a clarified sugar solution using the sugar solution filtering device 1 will be described with reference to FIG. The explanation is made from the stock solution filtration step of collecting the clarified sugar solution from which the impurities in the stock solution are separated by filtering with the membrane separation means 20 using the sugar solution containing impurities as the stock solution.

  In the stock solution filtration step, first, a stock solution supply valve (not shown) provided in the stock solution pipe 11 is opened, and the sugar solution containing impurities is stored as a stock solution with the pump 14 and the circulation pump 32 stopped. Supply to tank 12. After storing a predetermined amount of the stock solution in the storage tank 12, the pump 14 is operated, and the stock solution is supplied to the membrane separation means 20 through the liquid tube 13, the liquid mixture tube 33, and the concentrated liquid tube 31 as the liquid to be treated. At this time, the air vent valve 72 is opened and the air in the membrane module 21 is discharged. After the air is discharged, the air vent valve 72 is closed, both the pump 14 and the circulation pump 32 are operated, and the flow rate of the liquid to be processed sent out from the pressure regulating valve 92 and the pump 14 is adjusted, and the raw liquid as the liquid to be processed Is pressurized to a predetermined value and supplied to the membrane separation means 20 via the liquid pipe 13 to be treated and the liquid mixture pipe 33. The flow rate of the liquid to be treated sent from the pump 14 is adjusted by adjusting the rotational speed of the pump 14 with an inverter. In the membrane separation means 20, the membrane liquid is subjected to membrane filtration treatment by the membrane module 21 in a cross flow manner. At this time, the valve 62 is opened, and the clarified sugar liquid from which impurities have been removed is recovered from the permeate side of the membrane module 21 via the clarified sugar liquid tube 61. On the other hand, the concentrated liquid in which impurities are concentrated is taken out from the liquid to be treated side of the membrane module 21 through the concentrated liquid pipe 31.

  The concentrated liquid taken out from the membrane module 21 is circulated to the membrane separation means 20 through the concentrated liquid pipe 31 and the mixed liquid pipe 33 by the circulation pump 32. A return pipe 91 is connected in the middle of the concentrate pipe 31, and a part of the concentrate is appropriately extracted from the concentrate circulation means 30 via the return pipe 91 and returned to the storage tank 12. The concentrate returned to the storage tank 12 can be continuously or intermittently extracted according to the SS concentration of the liquid in the concentrate circulating means 30. On the other hand, a liquid pipe 13 to be processed is also connected to the concentrated liquid pipe 31, and the membrane separation means 20 is used as a liquid to be processed while appropriately mixing the liquid in the storage tank 12 with the concentrated liquid via the liquid pipe 13 to be processed. The stock solution is filtered. The liquid in the storage tank 12 has a lower SS concentration than the concentrated liquid in the concentrated liquid circulating means 30, and therefore the amount of concentrated liquid circulated, the amount returned to the storage tank 12, or the amount of liquid supplied in the storage tank 12 The SS concentration of the liquid to be treated to be supplied to the membrane separation means 20 can be adjusted by appropriately adjusting the slag, and sludge can be prevented from being deposited on the concentrate circulation means 30. The storage tank 12 is provided with a liquid level gauge 82, and a sugar solution containing impurities is continuously or intermittently supplied from the stock solution pipe 11 so that the amount of liquid inside does not become a predetermined amount or less.

  In the present embodiment, the concentration rate of the concentrated liquid increases as the stock solution supply amount supplied from the stock solution tube 11 and the clarified sugar solution withdrawn from the clarified sugar solution tube 61 increase. As a result, the SS concentration of the liquid to be processed including the stock solution and the concentrated solution gradually increases and reaches the concentration limit. In the present invention, the concentrated solution is circulated through the membrane separation means 20 and mixed with the undiluted solution to continue the undiluted solution filtration step for membrane filtration, and then the supply of the sugar solution containing impurities to the storage tank 12 is stopped. In this embodiment, the stock solution supply amount is measured by the flow meter 81 provided in the stock solution pipe 11, the time when a predetermined amount of stock solution is supplied is detected, and the supply of the stock solution is stopped at this time.

  A diafiltration filtration step in which, after stopping the supply of the stock solution, hot water at 60 to 80 ° C. is supplied from the dilution liquid pipe 51 to the storage tank 12 as the dilution liquid, and the sugar in the highly concentrated concentrate is recovered. Move on. In the present invention, it is preferable that the point of time when the concentration limit detected by the concentration limit detecting means is reached as the point of time when the stock solution filtering step is completed and the diafiltration step is started. In this embodiment, after the supply of the stock solution is stopped, the liquid in the storage tank 12 is supplied to the membrane separation means 20 while continuing to circulate the concentrate, and the liquid level gauge 82 in the storage tank 12 The time when the amount of the liquid remaining in the water reaches a predetermined value or less is detected as the time when the concentration limit is reached.

  In the diafiltration filtration step, warm water is supplied as a diluting solution instead of supplying the sugar solution containing impurities to the storage tank 12, the concentrated solution is diluted, and membrane filtration is performed by the membrane separation means 20. In the diafiltration filtration step, hot water is supplied to the storage tank 12 from the dilution liquid pipe 51, and the concentrated liquid returned from the concentrate circulation means 30 through the return pipe 91 is diluted to a predetermined pressure. Pressurized and supplied to the membrane separation means 20. In the membrane separation means 20, diafiltration filtration is performed by a cross-flow method using the membrane module 21 using the liquid in which the concentrated liquid is diluted as the liquid to be processed. At this time, the clarified sugar liquid from which impurities have been removed is recovered from the permeate side of the membrane module 21 via the clarified sugar liquid pipe 61, and the concentrated liquid pipe 31 is connected from the treated liquid side of the membrane module 21. Remove the concentrated solution.

  Also in the diafiltration step, the concentrated liquid taken out from the membrane module 21 is circulated to the membrane separation means 20 through the concentrated liquid pipe 31 and the mixed liquid pipe 33 by the circulation pump 32. A part of the concentrated liquid is returned to the storage tank 12 via the return pipe 91. Warm water is supplied from the dilution liquid pipe 51 to the storage tank 12 appropriately or continuously, and the concentrated liquid is diluted and supplied to the membrane separation means 20. Also in the diafiltration step, a part of the concentrated liquid in the concentrated liquid circulating means 20 is extracted and returned to the storage tank 12, and the liquid in the storage tank 12 having a lower SS concentration is mixed with the concentrated liquid. And supplied to the membrane separation means as a liquid to be treated. For this reason, it is possible to prevent sludge from accumulating in the concentrate circulating means 30 by circulating the concentrate. The warm water is supplied in an amount of about 5 to 20% by weight, preferably about 10 to 15% by weight of the stock solution treated in the stock solution filtration step. The supply of warm water is provided with a dilution liquid flow meter 52 in the dilution liquid pipe 51, whereby the supply amount can be measured and adjusted.

  In the diafiltration process, after supplying a predetermined amount of hot water, the supply of hot water is stopped. In this state, diafiltration filtration is continued for a while, and the diafiltration filtration step is terminated when the liquid level in the storage tank 12 becomes lower than the lower limit value. After finishing the diafiltration step, the filtration residue remaining in the membrane separation means 20 and the like is discharged from the discharge pipe 41 by opening the discharge valve 42. The discharged concentrated residue can be reused as feed. After the filtration residue is discharged, a sugar solution containing impurities is newly supplied to the sugar solution filtering device 1 as a stock solution, and the above stock solution filtration step and diafiltration filtration step are repeated. In addition, after discharging | emitting a filtration residue, before supplying the sugar liquid containing an impurity, it is preferable to wash | clean the sugar liquid filtration apparatus 1 with a chemical | medical agent. In the chemical cleaning, a cleaning liquid such as a sodium hydroxide solution is supplied to the storage tank 12 from a cleaning liquid supply means (not shown), and the cleaning liquid is passed through the entire liquid supply means 10, membrane separation means 20 and concentrated liquid circulation means 30. After the entire apparatus is cleaned, warm water is supplied instead of the cleaning liquid and the same operation is performed to rinse and clean the entire apparatus.

  In the present invention, the concentrated solution is circulated and supplied to the membrane separation means together with the stock solution to produce a clarified sugar solution and concentrate the stock solution. For this reason, without providing a plurality of membrane separation means, the stock solution can be concentrated to a high concentration of about 10 to 20 times, and the clarified sugar solution can be recovered with high efficiency. Further, in the present invention, normal membrane filtration and diafiltration filtration for diluting the concentrated solution can be performed with a single membrane separation means, thus simplifying the apparatus and reducing the sugar recovery rate. Is not reduced.

A clarified sugar solution was produced using a glucose solution obtained by treating starch with an enzyme using the sugar solution filtering apparatus shown in FIG. As the stock glucose solution, the following composition and properties were used.
"Glucose solution"
Glucose concentration: 25% by weight
SS concentration: 0.4% by weight
Viscosity: viscosity 0.8 cp
Temperature: 60 ° C

The specifications of the membrane module are as follows.
"Membrane module"
Used membrane: Tubular type sintered metal membrane formed by sintering titanium dioxide on the inner surface of a tubular metal membrane obtained by sintering stainless steel 316L particles Pore diameter: 0.1 μm
Film diameter: 19mm
Film length: 3m
Number of membranes: 80 membrane areas: 14 m ²
Membrane module volume: 100L

  The operation of the sugar liquid filtration apparatus is to adjust the flow rate of the liquid to be processed sent out by the pump and to adjust the flow rate of the liquid to be processed so that the outlet pressure of the membrane module is constant at 0.3 Mpa using the pressure adjusting valve provided in the return pipe. Pressurized. The glucose solution was replenished appropriately 12 kL from the stock solution tube to the storage tank and supplied to the membrane separation means. The concentrated liquid discharged from the membrane separation means was circulated to the membrane separation means at a flow rate of 3,000 L / min. The concentrated solution tube and the mixed solution tube were made of stainless steel having a diameter of 200 mm, and the volume thereof was 80 L. A part of the concentrate was returned to the storage tank, and the return of the concentrate was adjusted to 6,000 L / hr by the pressure adjustment valve of the return pipe. In this stock solution filtration step, the concentration limit value of the liquid to be treated was set to a value (concentration magnification 20 times) at which the SS concentration in the liquid to be treated was 20 times that of the glucose solution that was an untreated stock solution. Based on the SS concentration of the stock solution, the concentration rate of the membrane module, and the circulation amount of the concentrate, the time when 12 kL of the stock solution is supplied and the remaining amount of the concentrate reaches 0.6 kL is calculated as the time when the liquid to be processed reaches the concentration limit value did. Then, the supply of the stock solution is stopped when 12 kL of the stock solution is supplied by the flow meter 81 provided in the stock solution pipe, and then the time when the liquid level falls below the lower limit value by the liquid level meter provided in the storage tank (the concentrated solution is 0 The time when the liquid to be treated reached the concentration limit was detected.

  When the liquid to be treated reaches the concentration limit, 1.5 kL of 60 ° C. warm water is divided into 0.1 kL at a time, and diafiltration is performed while circulating the concentrated liquid. Was recovered. Diafiltration filtration was terminated when the liquid in the storage tank became a predetermined amount or less, the discharge valve of the discharge pipe was opened, and the concentrated liquid in the apparatus was discharged out of the apparatus as a concentrated residue. This treatment was repeated 5 times to obtain a 64 kL clarified sugar solution (glucose concentration: 23 wt%, SS concentration: 0%) in substantially 25 hours. The recovery rate of glucose contained in the clarified sugar solution was 99.7%.

[Reference example]
As a reference example, the same stock solution as in the example was filtered by the sugar solution filtering device 2 shown in FIG. The sugar liquid filtration device 2 in FIG. 3 includes a raw liquid filtration system including a first treated liquid supply means 510, a first membrane separation means 520, and a first concentrated liquid circulation means 530, and a second treated liquid supply. A diafiltration filtration system comprising means 610, second membrane separation means 620, and second concentrate circulating means 630 is provided. The first treated liquid supply means 510 includes a first raw liquid pipe 511, a first storage tank 512, a first pump 514, and a first treated liquid pipe 513, but does not include a dilution liquid supply mechanism. The first membrane separation means 520 includes a first membrane module, and a first clarified sugar solution tube 561 is connected to the first membrane module. The first concentrated liquid circulation means 530 includes a first concentrated liquid pipe 531, a first circulating pump 532, and a first mixed liquid pipe 533. However, the first concentrated liquid pipe 531 is not provided with a return pipe, and a liquid feeding pipe 700 for supplying the concentrated liquid to the diafiltration filtration system is provided instead of the discharge pipe in the sugar liquid filtration device of the embodiment. It is connected. The liquid feeding pipe 700 supplies the concentrated liquid to the second storage tank 612 via the relay tank 701 and the second raw liquid pipe 611.

  The second processed liquid supply means 610 includes a second raw liquid pipe 611, a second storage tank 612, a second pump 614, and a second processed liquid pipe 613. The second storage tank 612 is connected with a dilution liquid pipe 651 for supplying a dilution liquid, but is not provided with a flow meter as a concentration limit detecting means. The second membrane separation means 620 includes a second membrane module, and a second clarified sugar solution tube 661 is connected to the second membrane module. The second concentrated liquid circulation means 630 includes a second concentrated liquid pipe 631, a second circulating pump 632, and a second mixed liquid pipe 633. A return pipe 691 is connected to the second concentrated liquid pipe 631, and the second concentrated liquid pipe 631 is concentrated. A discharge pipe 641 for discharging the residue is connected.

  The first membrane module and the second membrane module of the sugar liquid filtration device 2 of the reference example are the same as those in the example, and the configurations having the same names as those in the examples are the same as those in the examples. The first membrane module and the second membrane module are provided with first and second air venting means, and a valve is provided for the first clarified sugar solution tube 561 and the second clarified sugar solution tube 661, and a return tube. Are provided with pressure regulating valves, which are not shown.

  In the reference example, 12 kL of the stock solution is supplied to the first storage tank 512 via the first stock solution pipe 511. The stock solution in the first storage tank 512 is supplied to the first membrane separation means 520 through the first pump 514, the first liquid pipe 513 to be treated, the first circulation pump 532, and the first liquid mixture pipe 533. In the first membrane separation means 520, the concentrate is mixed with the stock solution while being circulated through the concentrate pipe 531, the first circulation pump 532, and the first mixed liquid pipe 533 to obtain a liquid to be treated, and the first membrane separation means 520. Filter with a cross flow method. The concentrated liquid discharged from the first membrane separation means 520 is circulated to the first membrane separation means 520 but is not returned to the first storage tank 512. However, a part of the concentrated liquid is supplied to the diafiltration system through the liquid feeding pipe 700 and the relay tank 701.

  The second storage tank 612 stores the concentrated liquid discharged from the first membrane separation means 520 through the second stock solution pipe 611. Further, 1.5 kL of hot water at a temperature of 60 ° C. is diluted as a dilution liquid from the dilution liquid pipe 651 by a constant volume of 0.1 kL to the second storage tank 612, and the second membrane separation means 620 uses a cross-flow type. Diafiltration was performed at. A clarified sugar solution was recovered from the second clarified sugar solution tube 661. On the other hand, the concentrate discharged from the second membrane separation means 620 was circulated to the second membrane separation means 620 via the second concentrate liquid pipe 631, the second circulation pump 632 and the second mixed liquid pipe 633. A part of the concentrated liquid was returned to the second storage tank 612 via the return pipe 691.

  A discharge pipe 641 was connected to the second concentrated liquid pipe 631, and the concentrated residue was appropriately discharged. In the reference example, the total amount of the concentrated liquid discharged from the first membrane separation unit 520 is configured to be concentrated and diafiltered by the second membrane separation unit 620 with the same configuration as the example. For this reason, in the stock solution filtration system that performs filtration without diluting the stock solution, the stock solution is not concentrated to the concentration limit. On the other hand, in the diafiltration filtration system, the concentrated liquid discharged from the first membrane separation means 520 was diluted and subjected to diafiltration filtration to recover a clarified sugar solution.

  As a result, a clarified sugar solution of 54 kL (glucose concentration of 23% by weight, SS concentration of 0%) was obtained from the starch saccharified solution by treatment for 25 hours. The recovery rate of glucose contained in the clarified sugar solution was 99.7% as in the example. In the examples, a clarified sugar solution of 64 kL was obtained at a filtration time of 25 hours, whereas a clarified sugar solution of 54 kL was only obtained in the reference example.

  The liquid filtration device of the present invention can be used for filtering a liquid containing an insoluble suspension to obtain a clear liquid in which a target substance in the liquid is dissolved. In particular, it can be used to produce a clarified sugar solution from which impurities such as fatty acids are removed.

It is a schematic diagram of the sugar liquid filtration apparatus which is one Embodiment of this invention. It is sectional drawing of the membrane module of FIG. It is a schematic diagram of the sugar liquid filtration apparatus of a reference example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sugar liquid filtration apparatus 10 To-be-processed liquid supply means 20 Membrane separation means 21 Membrane module 30 Concentrated liquid circulation means 40 Discharge mechanism 50 Liquid addition mechanism 60 Clarified sugar liquid collection mechanism 70 Air vent mechanism 90 Return mechanism

Claims (5)

Membrane separation means having a structure partitioned into a liquid to be treated side and a permeate liquid side through a permeable membrane that separates impurities in the liquid to be treated, and a liquid to be treated with respect to the liquid to be treated of the membrane separation means The liquid to be treated is supplied to the membrane separation means, and the concentrated liquid in which the impurities in the liquid to be treated are concentrated by the membrane separation means is discharged from the liquid to be treated side of the membrane separation means. A concentrated liquid circulating means for circulating the discharged concentrated liquid to the treated liquid side of the membrane separating means,
The treatment liquid supply means is connected to the concentrate circulation means, and supplies the treatment liquid to the membrane separation means via the concentrate circulation means, and to the membrane separation means A liquid filtration apparatus comprising a liquid addition mechanism for supplying a dilution liquid for performing diafiltration filtration.   Concentration limit detection means for detecting that the liquid to be treated containing the circulated concentrated liquid has been concentrated to the concentration limit, and when the concentration limit is detected by the concentration limit detection means, the liquid to be processed is supplied. 2. The liquid filtration apparatus according to claim 1, wherein a dilution liquid is supplied from the means, and diafiltration is performed by the membrane separation means.   The liquid filtration device according to claim 1 or 2, wherein the liquid filtration device is a sugar solution filtration device that obtains a clarified sugar solution from which impurities are removed by filtering a sugar solution containing impurities. Clarification is achieved by removing impurities in the sugar solution containing impurities using a membrane separation means having a structure that is divided into the treatment liquid side and the permeate side through a permeable membrane that separates impurities in the treatment liquid. A method for producing a clarified molasses to obtain a molasses,
While circulating the treatment liquid on the treatment liquid side of the membrane separation means, the treatment liquid is separated into a clarified sugar liquid and a concentrated liquid by supplying the treatment liquid under pressure to the treatment liquid side. A stock solution filtration step to obtain a clarified sugar solution,
A diafiltration step of further filtering the clarified sugar solution from the concentrated solution in a state in which the liquid to be treated is circulated after the stock solution filtration step proceeds, and producing a clarified sugar solution comprising Method. The method for producing a clarified sugar liquid according to claim 4, wherein the diafiltration filtration step is performed when the liquid to be treated reaches a concentration limit.

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