Method and system for producing phosphorus compounds

Abstract

To provide a production method of a phosphorus compound and a production system of a phosphorus compound capable of efficiently conducting transport of phosphorus compound particles from a cleaning apparatus.SOLUTION: A production method of a phosphorus compound includes: putting a sludge including phosphorus in a reaction tank 1 where a crystallization reaction liquid using a seed crystal of a phosphorus compound is accommodated, followed by blending, for crystallization of phosphorus compound particles in a crystallization reaction liquid; withdrawing the crystallization reaction liquid including the phosphorus compound particles from the reaction tank 1; recovering the phosphorus compound particles from the crystallization reaction liquid, followed by retention in the cleaning apparatus 5 and cleaning; measuring a retention amount of the phosphorus compound particles in the cleaning apparatus 5; and, based on a measuring result of the retention amount of the phosphorus compound particles, controlling at least either the transport amount or transport frequency of the phosphorus compound particles on transporting the phosphorus compound particles after cleaning to an outside of the cleaning apparatus 5.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for producing a phosphorus compound and a production system for a phosphorus compound.

Background Art

[0002] As a method for separating nitrogen components and phosphorus components from organic wastewater or sludge, magnesium ions, calcium ions, etc. are added to the organic wastewater or sludge, and phosphorus contained in the wastewater is crystallized as a phosphorus compound such as magnesium ammonium phosphate (MAP) or hydroxyapatite (HAP), and a technique for separating and recovering the crystallized product is known. Such crystallization technology uses relatively little chemical agents, mechanical power, thermal energy, etc., is inexpensive, can stably recover phosphorus components, and the recovered phosphorus compound has added value as an excellent fertilizer. Therefore, it is useful as a recovery technology or production technology for phosphorus compounds that is excellent in terms of effective use of resources.

[0003] Japanese Patent Application Laid-Open No. 2004-160304 (Patent Document 1) discloses that in an anaerobic digestion process for anaerobically treating organic wastewater, MAP particles generated in sludge are separated by a liquid cyclone or the like to obtain a MAP separation and concentration liquid containing MAP particles. After that, magnesium ions are newly added to the MAP separation and concentration liquid, and by reacting with the dissolved phosphorus component, new MAP is laminated on the surface of the MAP particles present in the MAP separation and concentration liquid to recover them as MAP particles.

[0004] Japanese Patent Application Laid-Open No. 2002-370094 (Patent Document 2) describes an example of an apparatus for crystallizing and removing phosphorus in treated water on the surface of magnesium ammonium phosphate particles flowing in a crystallization reaction tank.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

[0006] The phosphorus compound particles generated in the crystallization reaction tank are separated from the crystallization reaction solution using a separation device such as a liquid cyclone, and then introduced into a washing device to remove any sludge or other substances adhering to the surface. After being washed in the washing device, the phosphorus compound particles are withdrawn from the washing device and sent to drying equipment such as a dewatering device.

[0007] However, the concentration of components in organic wastewater or sludge supplied to the reaction tank may fluctuate depending on the season or regional characteristics. When the concentration of components in organic wastewater or sludge fluctuates, the treatment conditions for the crystallization reaction in the reaction tank change, and the particle size and amount of phosphorus compound particles generated in the reaction tank also change. As a result, the amount of phosphorus compound particles recovered into the washing device also changes. The washing device that washes the phosphorus compound particles always maintains a certain amount of phosphorus compound particles. However, if this amount exceeds an appropriate range, various problems may occur, such as blockage of pipes when transferring phosphorus compound particles from the washing device, or insufficient storage of phosphorus compound particles in the washing device, preventing proper transfer of the phosphorus compound particles.

[0008] In view of the above problems, the present invention provides a method for producing phosphorus compounds and a system for producing phosphorus compounds that can efficiently transfer phosphorus compound particles from a washing device.

[0009] As a result of diligent research to solve the above problems, the inventors of the present invention have found that it is useful to measure the amount of phosphorus compound particles stored in the washing device using a measuring means.

[0010] To solve the above problems, the present invention, in one aspect, is a method for producing phosphorus compounds, which includes introducing phosphorus-containing sludge into a reaction tank containing a crystallization reaction solution using seed crystals of a phosphorus compound and mixing it to crystallize phosphorus compound particles in the crystallization reaction solution, withdrawing the crystallization reaction solution containing the phosphorus compound particles from the reaction tank, recovering the phosphorus compound particles from the crystallization reaction solution and storing them in a washing device for washing, measuring the amount of phosphorus compound particles stored in the washing device, and controlling at least one of the amount or frequency of transfer of the phosphorus compound particles when transferring the washed phosphorus compound particles out of the washing device based on the measurement result of the amount of phosphorus compound particles stored.

[0011] In one embodiment of the phosphorus compound production method according to the present invention, the amount of phosphorus compound particles stored is determined by acquiring image data of the height of the interface of the phosphorus compound particle layer, which is identified from outside the washing device through a window provided in the washing device, and performing image determination on the image data.

[0012] In one embodiment, the method for producing phosphorus compounds according to the present invention includes measuring the amount of phosphorus compound particles stored in a washing device by measuring the weight of the washing device.

[0013] In another embodiment, the method for producing phosphorus compounds according to the present invention includes measuring the amount of phosphorus compound particles stored in a washing device by measuring the height of the interface of the phosphorus compound particle layer stored in the washing device using an ultrasonic measuring device.

[0014] In yet another embodiment, the method for producing phosphorus compounds according to the present invention includes inputting image data of the height of the interface of the phosphorus compound particle layer to be measured into a model constructed by a machine learning algorithm that uses training data including feature quantities obtained from image data of the height of the interface of the phosphorus compound particle layer to be measured, which is identified from outside the washing device through a window provided in the washing device, and feature quantities representing the amount of phosphorus compound particles stored in the washing device associated with the image data, and outputting a predicted value of the amount of phosphorus compound particles to be measured, thereby measuring the amount of stored phosphorus compound particles.

[0015] In yet another embodiment, the method for producing phosphorus compounds according to the present invention further includes a feature quantity in which the training data includes at least one of a suitable transport amount or transport frequency for the transport of phosphorus compound particles associated with image data of the height of the interface of the phosphorus compound particle layer, and further outputs at least one of a suitable transport amount or transport frequency for the phosphorus compound particles for the target of measurement by inputting image data of the height of the interface of the phosphorus compound particle layer to be measured into the model.

[0016] In yet another embodiment of the phosphorus compound production method according to the present invention, the method further includes calculating the seed crystal concentration in the crystallization reaction solution in a reaction vessel containing seed crystals based on the measurement result of the amount of phosphorus compound particles stored in the washing device, and further controlling at least one of the amount or frequency of withdrawal of the crystallization reaction solution from the reaction vessel based on the calculation result of the seed crystal concentration.

[0017] In another aspect, the present invention is a phosphorus compound production system comprising: a reaction tank for generating phosphorus compound particles from phosphorus-containing sludge using a crystallization reaction with a seed crystal of a phosphorus compound; an extraction device for withdrawing a crystallization reaction solution containing phosphorus compound particles from the reaction tank; a separation device for separating phosphorus compound particles from the crystallization reaction solution withdrawn by the extraction device; a washing device for washing the phosphorus compound particles separated by the separation device; a transfer device for transferring the phosphorus compound particles in the washing device to the outside of the washing device; a measuring device for measuring the amount of phosphorus compound particles stored in the washing device; and a transfer control unit for controlling at least one of the amount or frequency of transfer of phosphorus compound particles when transferring the phosphorus compound particles in the washing device to the outside of the washing device, based on the measurement result of the amount of phosphorus compound particles stored in the washing device.

[0018] In yet another aspect, the present invention provides a production system for a phosphorus compound, comprising a reaction tank that generates phosphorus compound particles from sludge containing phosphorus by using a crystallization reaction with seed crystals of the phosphorus compound, a drawing device that draws out a crystallization reaction solution containing the phosphorus compound particles from the reaction tank, a separation device that separates the phosphorus compound particles from the crystallization reaction solution drawn out by the drawing device, a washing device that washes the phosphorus compound particles separated by the separation device, a transfer device that transfers the phosphorus compound particles in the washing device to the outside of the washing device, a measuring device that measures the storage amount of the phosphorus compound particles in the washing device, a drawing control unit that calculates the seed crystal concentration in the crystallization reaction solution in the reaction tank containing the seed crystals based on the measurement result of the storage amount of the phosphorus compound particles in the washing device and controls at least one of the drawing amount or the drawing frequency of the crystallization reaction solution from the reaction tank based on the calculation result of the seed crystal concentration.

Advantages of the Invention

[0019] According to the present invention, it is possible to provide a production method and a production system for a phosphorus compound that can efficiently transfer the phosphorus compound particles from the washing device.

Brief Description of the Drawings

[0020] [Figure 1] FIG. 15 is a schematic diagram showing an example of a treatment apparatus for organic wastewater according to an embodiment of the present invention. [Figure 2] FIG. 18 is a block diagram showing an example of an image determination apparatus according to an embodiment of the present invention. [Figure 3] FIG. 3(a) is a block diagram showing an example of a weight measurement apparatus according to an embodiment of the present invention, and FIG. 3(b) is a block diagram showing an example of an ultrasonic measurement apparatus according to an embodiment of the present invention. [Figure 4] FIG. 24 is a schematic diagram showing the composition ratio of a crystallization reaction solution containing phosphorus compound particles that is drawn from the bottom of the reaction tank through a drawing device according to an embodiment of the present invention, supplied to the apparatus, and sent to the washing device.

Embodiments for Carrying Out the Invention

[0021] Embodiments of the present invention will be described below with reference to the drawings. In the following drawings, identical or similar parts are denoted by identical or similar reference numerals. The embodiments shown below are illustrative examples of devices and methods for realizing the technical idea of ​​this invention, and the technical idea of ​​this invention is not limited to the structure, arrangement, etc., of the components described below.

[0022] As shown in Figure 1, the phosphorus compound production system according to an embodiment of the present invention comprises a reaction vessel 1, an extraction device 3 for extracting a crystallization reaction solution containing phosphorus compound particles from the reaction vessel 1, a separation device 4 for separating phosphorus compound particles from the crystallization reaction solution extracted by the extraction device 3, a washing device 5 for washing the phosphorus compound particles separated by the separation device 4, a transfer device 8 for transferring the phosphorus compound particles in the washing device 5 to the outside of the washing device 5, a measuring device 6 for measuring the amount of phosphorus compound particles stored in the washing device 5, and a transfer control device 74 for controlling at least one of the amount or frequency of transfer of phosphorus compound particles when transferring the phosphorus compound particles in the washing device 5 to the outside of the washing device 5, based on the measurement result of the amount of phosphorus compound particles stored in the washing device 5.

[0023] Reaction tank 1 is a crystallization reaction tank that generates phosphorus compounds from phosphorus-containing sludge using a crystallization reaction with seed crystals of phosphorus compounds. A chemical agent is supplied to reaction tank 1 via a chemical supply device 2 to react with phosphorus ions in the input sludge and form phosphorus compound particles. The phosphorus compound includes magnesium ammonium phosphate (MAP) or hydroxyapatite (HAP).

[0024] Seed crystals of phosphorus compounds are mixed into the crystallization reaction solution to grow phosphorus in the input sludge into phosphorus compound particles of a predetermined particle size. In one embodiment, when obtaining MAP as phosphorus compound particles, the particle size refers to crystals with a particle size of 30 μm or larger, although this is not limited to the following. The particle size of the phosphorus compound particles is determined by the 50% diameter (D) of the particle size distribution measured, for example, by a laser diffraction / scattering particle size distribution analyzer (LA-910, Horiba, Ltd.) and an ultrasonic sieve (Shodex PS microsieve, Showa Denko K.K.). 50This shows the particle size of the seed crystal of the phosphorus compound particles can be appropriately set by a person skilled in the art depending on the shape, volume, operating conditions, etc. of the reaction vessel 1, and is of course not limited to this example.

[0025] The pH of the crystallization reaction solution in reaction vessel 1 is measured by a pH meter 11 installed in reaction vessel 1. Crude phosphorus compound particles that have grown to a size suitable for recovery, i.e., a particle size equal to or larger than that of the seed crystal, are constantly flowing throughout reaction vessel 1 due to the turbulence created by the stirrer in reaction vessel 1, maximizing the opportunity for contact with the substrate components adhering to the MAP particles.

[0026] The suspension of the crystallization reaction liquid containing crude phosphorus compound particles dispersed throughout the reaction tank 1 is drawn out of the reaction tank 1 by an extraction device 3 equipped with piping and a pump 31 and supplied to a separation device 4. A portion of the crystallization reaction liquid drawn out of the reaction tank 1 by the extraction device 3 is separated into phosphorus compound particles and separated sludge by a separation device 4b that utilizes centrifugal separation, such as a liquid cyclone. The phosphorus compound particles separated in the separation device 4b are returned to the reaction tank 1. The remaining crystallization reaction liquid drawn out of the reaction tank 1 by the extraction device 3 is separated into phosphorus compound particles and separated sludge by a separation device 4a. The concentrated sludge containing a large amount of phosphorus compound particles separated in the separation device 4a is sent to a washing device 5. The separated sludge separated in the separation devices 4a and 4b is sent to the sludge treatment process.

[0027] The cleaning device 5 includes a cleaning tank 50 for storing and cleaning the phosphorus compound particles separated by the separation device 4a, and a window 51 positioned on the outer wall surface of the cleaning tank 50, which allows the phosphorus compound particles inside the cleaning tank 50 to be identified from outside the cleaning tank 50. The window 51 may be provided with a scale 52 for measuring the height of the interface I of the phosphorus compound particles stored in the cleaning device 5. The window 51 may also be equipped with a cleaning mechanism (not shown) for preventing fouling. A pipe 53 for supplying cleaning water into the cleaning tank 50 is connected to the bottom of the cleaning tank 50. When cleaning water is supplied from the bottom of the cleaning tank 50 via the pipe 53, an upward flow is generated inside the cleaning tank 50, pushing out impurities such as sludge and debris adhering to the phosphorus compound particles upward.

[0028] Impurities pushed upward from the washing tank 50 are discharged to the outside of the washing device 5 along with the washing wastewater via piping 54 connected to the top of the washing tank 50. After a predetermined washing treatment is performed on the phosphorus compound particles supplied to the washing device 5, they are stored in the washing device 5 and transferred to the outside of the washing device 5 via a transfer device 8 connected to the washing device 5. After being dried by a dewatering device, a dryer (not shown), etc., they are recovered. From the viewpoint of simplifying and miniaturizing the device, it is preferable to use an air-lift pump as the transfer device 8.

[0029] The reaction tank 1 is connected to a chemical supply device 2 equipped with a pump and piping for supplying chemicals into the reaction tank 1, and a sludge supply device 10 for supplying input sludge into the reaction tank 1. The sludge supply device 10 may, for example, include a storage tank, pump and piping for storing and supplying the input sludge into the reaction tank 1, but is not limited to this example. The piping that supplies the input sludge from the sludge supply device 10 to the reaction tank 1 may be equipped with a phosphate concentration measuring device 1a for measuring the phosphate concentration of the input sludge and a pH meter 12 for measuring the pH of the input sludge. The chemical supply device 2 may, but is not limited to this example, include a tank for containing magnesium-containing chemicals such as magnesium hydroxide and calcium hydroxide, a pump and piping for supplying the chemicals from the tank, and a dilution tank for diluting the chemicals as needed.

[0030] The sludge supply device 10 and the chemical supply device 2 are connected to the control device 7. The control device 7 is composed of a general-purpose computer or the like. The control device 7 may be installed at the site where the reaction tank 1 is installed, or it may be installed on a server in the cloud or the like. The control device 7 includes a calculation unit 70, a chemical supply control unit 71, a withdrawal control unit 72, a washing control unit 73, a transfer control unit 74, and a learning unit 75.

[0031] The calculation unit 70 calculates the parameters necessary for the operation control of the reaction vessel 1, the extraction device 3, the separation device 4, the washing device 5, the measuring device 6, and the transfer device 8, and outputs predetermined control signals to the reaction vessel 1, the extraction device 3, the separation device 4, the washing device 5, the measuring device 6, and the transfer device 8 based on the calculation results. The chemical supply control unit 71 outputs a control signal to control the supply flow rate and supply time of the chemical supplied by the chemical supply device 2 to the reaction vessel 1, based on the input of setting conditions for the ratio of magnesium to phosphorus (Mg / P ratio) in the reaction vessel 1. The extraction control unit 72 outputs a control signal to control the extraction process of the extraction device 3 to extract the crystallization reaction solution from the reaction vessel 1, specifically the amount and frequency of extraction of the crystallization reaction solution, so that the seed crystal concentration in the reaction vessel 1 is maintained within a certain range. The washing control unit 73 outputs a control signal to control the washing process of the washing device 5. The transfer control unit 74 outputs a control signal to transfer phosphorus compound particles in the washing device 5 to the outside of the washing device 5. The learning unit 75 uses a machine learning algorithm to create a trained model that outputs predetermined explanatory variables in response to a predetermined target variable input.

[0032] In a crystallization reaction, the nucleation (crystallization) process that occurs due to the presence of seed crystals in the solution is called "secondary nucleation." To ensure that the crystallization reaction proceeds stably during secondary nucleation, it is important to secure a sufficient surface area (seed crystal concentration) of seed crystals in the reaction vessel 1. If the seed crystal concentration in the reaction vessel 1 is low, there will be insufficient surface area of ​​seed crystals to promote the crystallization reaction, and the removal performance of phosphorus, which is a dissolved ion contained in the input sludge, will deteriorate. If the seed crystal concentration is too high, too many phosphorus compound particles will be generated in the reaction vessel 1, which may clog the piping and pumps of the extraction device 3. Here, "seed crystal concentration" refers to the concentration of seed crystals, that is, the concentration (g-MAP / L) of phosphorus compound particles having a particle size that functions as seed crystals in the crystallization reaction. Although not limited to the following, in this embodiment, it refers to the concentration of phosphorus compound particles with a particle size of 30 μm or more present in the crystallization reaction solution.

[0033] In crystallization reactions, the surface area of ​​the seed crystal is generally considered a primary operating factor, rather than the seed crystal concentration. In this system, the seed crystal size in the reaction tank 1 can be kept constant by using the extraction device 3 and the separation device 4b to extract and return seed crystals from the reaction tank 1 at predetermined frequencies. Furthermore, in this system, the surface area of ​​the seed crystal can be controlled by appropriately managing the concentration of seed crystals in the reaction tank 1. Consequently, the crystallization rate of the seed crystal can also be controlled arbitrarily. The seed crystal size may fluctuate depending on the equipment characteristics, regional characteristics, and changes in the properties of the input sludge. In such cases, the surface area and seed crystal concentration are calculated by further considering the fluctuations in seed crystal size.

[0034] Currently, the analysis of the seed crystal concentration in reaction tank 1 is performed only by periodic manual analysis. Furthermore, the number and frequency of withdrawals of the crystallization reaction solution containing phosphorus compound particles from reaction tank 1, as well as the amount and frequency of transfer of phosphorus compound particles by the transfer device 8 in the washing device 5, are controlled only at predetermined times. However, the phosphoric acid (PO4-P) concentration of the input sludge varies depending on the type and properties of the input sludge.

[0035] The magnesium or calcium concentration of the chemicals introduced into reaction tank 1 may also be excessive or insufficient depending on variations in the properties of the sludge, regional characteristics, temperature, etc. Due to these various factors, it is currently difficult to maintain the crystallization reaction in reaction tank 1 in an optimal state under uniform operating conditions. The amount of phosphorus compound particles recovered into the washing device 5 also changes according to the state of the crystallization reaction in reaction tank 1. Therefore, if the method of transferring the washed phosphorus compound particles from the washing device 5 at a constant amount and frequency is used, problems such as pipe blockage or pressure increase may occur during transfer.

[0036] According to this embodiment, a measuring device 6 is provided to measure the amount of phosphorus compounds stored in the washing device 5. The transfer control unit 74 controls the transfer process of phosphorus compound particles from the washing device 5 to the outside of the washing device 5, according to the measurement results of the measuring device 6, so that the amount of phosphorus compound particles and impurities attached to the phosphorus compound particles stored in the washing device 5 is maintained within an appropriate range. As a result, the transfer conditions of the transfer device 8 can be made to follow the internal conditions of the washing device 5, thereby increasing the purity of the recovered phosphorus compound particles and stably improving production efficiency.

[0037] Various measuring devices can be used as the measuring device 6 capable of measuring the amount of at least one of phosphorus compound particles or impurities stored in the washing device 5. Several examples are described below.

[0038] (Image recognition device) As the measuring device 6 for measuring the amount of phosphorus compounds stored in the washing device 5, an image determination device 6b is preferably used to measure the amount of phosphorus compound particles stored in the washing device 5 by image determination of the height of the interface of the phosphorus compound particle layer mainly containing phosphorus compound particles stored in the washing device 5. The image determination device 6b preferably acquires image data of the height of the interface of the phosphorus compound particle layer stored in the washing device 5 through a window portion 51 provided in the washing device 5 that allows the phosphorus compound particles stored in the washing device 5 to be identified from outside the washing device 5, and performs image determination on the image data.

[0039] The crystallization reaction liquid withdrawn from reaction tank 1 is separated into phosphorus compound particles and separated sludge by centrifugal separation in separation device 4a. The phosphorus compound particles are then fed into washing device 5 to wash away impurities such as sludge and residue from the surface. If the amount and frequency of withdrawal of the crystallization reaction liquid from reaction tank 1 are constant, fluctuations in the phosphorus input load of the sludge fed into reaction tank 1 will cause a change in the amount of phosphorus compound particles stored in washing device 5. By measuring the change in the amount of phosphorus compound particles stored in washing device 5 using image determination device 6b, it becomes possible to optimize at least one of the conditions for the amount or frequency of transfer of phosphorus compound particles by transfer device 8.

[0040] As shown in Figure 2, the image determination device 6b comprises an imaging unit 61b that captures still images or continuous images (moving images), and a processing unit 60b that performs predetermined calculations using the image data from the imaging unit 61b. The processing unit 60b is composed of a general-purpose computer or the like. The processing unit 60b may also include a graphics processor (GPU). A storage device (not shown) for storing the calculation results of the processing unit 60b and various information necessary for the processing of the processing unit 60b may be located inside or outside the processing unit 60b.

[0041] The processing by the processing unit 60b may be performed in the calculation unit 70 of the control device 7 in Figure 1 or on a server on the cloud (not shown). Although not shown, the processing unit 60b may be equipped with an input / output control device, and may receive input and output of various information from outside the processing unit 60b via the input / output control device, such as image data capturing the height of the interface of the phosphorus compound particle layer in the cleaning device 5 or a trained model for image judgment using machine learning. The processing unit 60b may also output the processing results of the processing unit 60b to the outside of this system via the input / output control device. The processing unit 60b may further be equipped with a display device for displaying the calculation processing results of the processing unit 60b to the operator.

[0042] The imaging unit 61b is not particularly limited as long as it is a device capable of capturing still or continuous images of the window 51 and scale 52 provided by the cleaning device 5. For example, a camera equipped with an image element such as a CCD image sensor or a CMOS image sensor is suitable as the imaging unit 61b. The imaging unit 61b can be installed anywhere as long as the interface between the phosphorus compound particle layer and the impurity layer of the window 51 can be captured from outside the cleaning device 5, and there may be one or more imaging units 61b. Typically, as shown in Figure 1, the imaging unit 61b is arranged to face the window 51.

[0043] The imaging unit 61b may also be equipped with lighting to illuminate the area around the window 51, which is the imaging area. The imaging unit 61b may also be equipped with a cover (not shown) to ensure a constant imaging environment. The shutter speed of the imaging unit 61b can also be adjusted as appropriate. The image data from the imaging unit 61b may be color or monochrome. Monochrome is preferable when performing binarization on the image data, but color is also acceptable. The lens equipped in the imaging unit 61b can be selected arbitrarily. To prevent the lens from getting dirty, a transparent plate or filter may be placed between the camera and the lens.

[0044] The processing unit 60b includes an image determination unit 62b that acquires image data including the window portion 51 of the cleaning device 5 captured by the imaging unit 61b and determines the height of the interface of the phosphorus compound particle layer stored in the cleaning device 5 identified from the image data by image determination, and a storage amount calculation unit 63b that calculates the amount of phosphorus compound particles stored in the cleaning device 5 based on the image determination result of the image determination unit 62b. The image determination unit 62b may acquire image data including the interface of the impurity layer identified from the window portion 51 of the cleaning device 5 and determine the height of the impurity layer stored in the cleaning device 5 identified from the image data by image determination. The storage amount calculation unit 63b may calculate the amount of impurities stored in the cleaning device 5 based on the image determination result of the image determination unit 62b. The processing unit 60b may further include a learning unit 64b that creates a trained model that outputs predetermined explanatory variables in response to the input of a predetermined target variable using a machine learning algorithm. The creation of the trained model may be performed by the learning unit 75 of the control device 7 in Figure 1.

[0045] The image determination unit 62b in Figure 2 is not limited in its specific operating procedure as long as it can detect the height of the interface of the phosphorus compound particle layer in the cleaning device 5. For example, the image determination unit 62b may perform various processing operations, including trimming, black and white conversion, binarization, multi-level conversion, standardization, and compression of the acquired image data, in order to improve the discriminability of the interface height of the phosphorus compound particle layer in the cleaning device 5. The image determination unit 62b may also determine changes in the interface height of the phosphorus compound particle layer in the cleaning device 5 by combining multiple image data captured by multiple imaging units 61b, or by combining multiple image data captured by the imaging unit 61b at different times. The image determination unit 62b may also divide the acquired image data into several objects and classify the divided objects by region. For example, it is preferable for the image determination unit 62b to classify the image data identified from the window 51 into regions, mainly consisting of the MAP layer containing phosphorus compound particles, the impurity layer composed of impurities such as scum, and the cleaning liquid layer, and then perform image determination of the interface height of the phosphorus compound particle layer in the cleaning device 5 based on this classification result.

[0046] The image determination unit 62b preferably performs image determination processing using a machine learning algorithm. For example, the image determination unit 62b may be configured to calculate the height of the interface of the phosphorus compound particle layer in the washing device 5 by performing calculation processing using a machine learning algorithm, using a model created with training data that associates image data containing at least information on the height of the interface of the phosphorus compound particle layer as a feature with information on the measurement result of the height of the interface of the phosphorus compound particle layer as a feature. Any machine learning algorithm such as support vector regression (SVR), partial least squares (PLS), random forest, or decision tree can be used. The training data may further include the seed crystal concentration in the reaction tank 1, the Mg / P ratio of the chemical supplied to the reaction tank 1, the phosphorus input load of the input sludge, the amount of extraction by the extraction device 3, and the extraction frequency.

[0047] The storage volume calculation unit 63b calculates the amount of phosphorus compound particles stored in the washing device 5 based on the image determination result of the image determination unit 62b, which determines the height of the interface of the phosphorus compound particle layer in the washing device 5. The storage volume calculation unit 63b can calculate the volume of phosphorus compound particles in the washing device 5 from, for example, the measurement result of the height of the interface of the phosphorus compound particle layer in the washing device 5 and the capacity of the washing device 5. From the calculation result of the volume of phosphorus compound particles, the storage volume calculation unit 63b calculates the amount (weight) of phosphorus compound particles stored in the washing device 5 using a pre-prepared known calibration curve (volume of phosphorus compound particles - weight of phosphorus compound particles).

[0048] The storage amount calculation unit 63b may estimate the amount of phosphorus compound particles stored in the washing device 5 by machine learning using a predetermined model that receives at least information from the image judgment result of the height of the interface of the phosphorus compound particle layer as an explanatory variable and outputs at least a predicted result of the amount of phosphorus compound particles stored in the washing device 5 as an objective variable. That is, it is preferable that the storage amount calculation unit 63b calculates the amount of phosphorus compound particles stored by inputting image data of the height of the interface of the phosphorus compound particle layer to be measured into a model constructed by a machine learning algorithm that uses training data including features obtained from image data of the height of the interface of the phosphorus compound particle layer to be measured, which is identified from outside the washing device 5 through the window portion 51 provided by the washing device 5, and features representing the amount of phosphorus compound particles stored in the washing device 5 associated with the image data, and outputting a predicted value of the amount of phosphorus compound particles to be measured. In this case, any machine learning algorithm such as support vector regression (SVR), partial least squares (PLS), random forest, decision tree, etc. can be used as described above. Deep learning can be preferably used among these, but is not limited to this. Machine learning may be supervised or unsupervised. The trained model constructed by machine learning may be updated periodically or at any time. There may be one or more trained models. The training data may include not only image data but also operating data of the system. The training data may include at least one feature quantity indicating at least one of the transport amount or transport frequency suitable for the transport of phosphorus compound particles, associated with image data of the interface height of the phosphorus compound particle layer. The storage amount calculation unit 63b may further output at least one of the transport amount or transport frequency of phosphorus compound particles suitable for the measurement target by inputting image data of the interface height of the phosphorus compound particle layer to be measured into the model.

[0049] Alternatively, the image determination device 6b may measure the height of the interface of the phosphorus compound particle layer in the washing device 5 by image determination of the interface height of the phosphorus compound particle layer in the washing device 5 and determining the difference between the image determination result of the interface height of the phosphorus compound particle layer and the set value of the interface height. Based on this measurement result, the transfer control unit 74 in Figure 1 can automatically manage the amount of phosphorus compound particles stored in the washing device 5 by adjusting the amount or frequency of extraction of phosphorus compound particles from the washing device 5. Furthermore, it is also possible to estimate the seed crystal concentration in the reaction vessel 1 based on the measurement result of the difference from the set value of the interface of the phosphorus compound particle layer. Based on this estimated seed crystal concentration, the amount of phosphorus compound particles to be recovered in the washing device 5 is determined by simulation or the like, and if it is expected that the amount of phosphorus compound particles recovered in the washing device 5 will exceed the set value during the next extraction process, it is preferable for the transfer control unit 74 to control the amount of extraction from the washing device 5 so that the amount of phosphorus compound particles stored in the washing device 5 (the interface height of the phosphorus compound particle layer) is within an appropriate range.

[0050] Furthermore, the image determination device 6b uses image determination based on a machine learning algorithm to identify the color inside the cleaning device 5, making it easy to distinguish between the region composed of a phosphorus compound particle layer, which normally contains many phosphorus compound particles that are white and transparent, and the impurity layer, which normally contains black plant-derived contaminants such as sesame seeds. This makes it possible to more accurately determine the amount of phosphorus compound particles and impurity layers stored. If the amount of phosphorus compound particles stored exceeds the appropriate range, the transfer control unit 74 increases or decreases the amount or frequency of transfer of phosphorus compound particles by the transfer device 8 so that the transfer amount or transfer frequency becomes appropriate. If the amount of impurity layers stored exceeds the appropriate range, the cleaning control unit 73 optimizes the cleaning process of the cleaning device 5 so that impurities can be selectively discharged from inside the cleaning device 5 through the piping 54.

[0051] (Weight measuring device) As another measuring device 6 for measuring the amount of phosphorus compounds stored in the washing device 5, a weight measuring device 6c is preferred, which measures the amount of phosphorus compound particles stored in the washing device 5 by measuring the weight of the washing device 5.

[0052] As shown in Figure 3(a), the weight measuring device 6c includes a weight measuring unit 61c for measuring the weight of the washing device 5, and a storage volume calculation unit 63c for calculating the amount of phosphorus compound particles stored in the washing device 5 from the weight measurement result of the weight measuring unit 61c. The storage volume calculation unit 63c does not necessarily have to be located within the weight measuring device 6c. The calculation processing of the storage volume calculation unit 63c may be performed by a calculation unit 70 of the control device 7, or by a server on the cloud.

[0053] The weight measuring unit 61c is not limited to any device capable of measuring the total weight inside the washing device 5, but it is preferable to use a load cell that can more easily detect changes in load over time. The storage volume calculation unit 63c can measure the weight change of the washing device 5 before and after the extraction of the crystallization reaction liquid from the reaction tank 1 by detecting changes in the electrical signal output from the load cell.

[0054] The specific gravity of water is 1.0 g / cm³. 3 The weight of MAP is 1.7g / cm³. 3 Therefore, the difference between the weight of the washing device 5 when it is filled with tap water and the weight of the washing device 5 when it is filled with water while phosphorus compound particles are present inside the washing device 5 changes depending on the weight of the phosphorus compound particles inside the washing device 5. Thus, the storage volume calculation unit 63c can calculate the weight of the phosphorus compound particles stored inside the washing device 5 from the relationship between the difference between the weight of the washing device 5 when it is filled with tap water and the weight of the washing device 5 when it is filled with water while phosphorus compound particles are present inside the washing device 5, and the specific gravity of the phosphorus compound. The storage volume calculation unit 63c may also be configured to automatically calculate the weight of the phosphorus compound particles inside the washing device 5 by using machine learning, as in the storage volume calculation unit 63b.

[0055] Furthermore, since the weight measuring device 6c directly measures the weight of the washing device 5, measurement errors caused by impurities such as plant-derived contaminants with low specific gravity are considered to be relatively small. Thus, the weight measuring device 6c can automatically measure the change in total weight before and after the withdrawal of the crystallization reaction solution containing phosphorus compound particles from the reaction vessel 1, thereby allowing the weight of the increase in phosphorus compound particles stored in the washing device 5 to be determined. Taking this increase in the weight of phosphorus compound particles into consideration, the transfer control unit 74 in Figure 1 can control the seed crystal concentration in the reaction vessel 1 to an appropriate range by controlling either the amount or frequency of withdrawal of phosphorus compound particles from the washing device 5.

[0056] (Ultrasonic measuring device) As another measuring device 6 for measuring the amount of phosphorus compounds stored in the cleaning device 5, an ultrasonic measuring device 6d is preferred, which measures the amount of phosphorus compound particles stored in the cleaning device 5 by measuring the height of the interface of the phosphorus compound particle layer stored in the cleaning device 5 using ultrasound.

[0057] As shown in Figure 3(b), the ultrasonic measuring device 6d includes an ultrasonic diagnostic unit 61d for measuring the height of the interface of the phosphorus compound particle layer in the cleaning device 5, and a storage volume calculation unit 63d for calculating the amount of phosphorus compound particles stored in the cleaning device 5 from the ultrasonic diagnostic results of the ultrasonic diagnostic unit 61d. The storage volume calculation unit 63d does not necessarily have to be located within the ultrasonic measuring device 6d. The calculation processing of the storage volume calculation unit 63d may be performed by a calculation unit 70 in the control device 7, or it may be performed on a server in the cloud.

[0058] The specific configuration of the ultrasonic diagnostic unit 61d is not limited. For example, the ultrasonic diagnostic unit 61d can be an ultrasonic-emitting interface measuring instrument that measures the interface of the phosphorus compound particle layer containing phosphorus compound particles in the cleaning device 5 by utilizing the propagation of ultrasonic signals through liquid, or an ultrasonic sludge interface meter. In the example shown in Figure 1, the tip of the ultrasonic diagnostic unit 61d is positioned on the upper part of the cleaning device 5 so as to face the water surface of the cleaning device 5, but the system is not limited to this example.

[0059] The storage volume calculation unit 63d calculates the amount of phosphorus compound particles stored in the cleaning device 5 based on the ultrasonic diagnostic results of the ultrasonic diagnostic unit 61d regarding the height of the interface of the phosphorus compound particle layer inside the cleaning device 5. The storage volume calculation unit 63b calculates the volume of phosphorus compound particles inside the cleaning device 5 from, for example, the ultrasonic diagnostic results of the interface height inside the cleaning device 5 and the capacity of the cleaning device 5. From the calculation result of the volume of phosphorus compound particles, the storage volume calculation unit 63d calculates the amount (weight) of phosphorus compound particles stored in the cleaning device 5 using a pre-established known calibration curve (volume of phosphorus compound particles - weight of phosphorus compound particles). The storage volume calculation unit 63d may be configured to automatically calculate the weight of phosphorus compound particles inside the cleaning device 5 by utilizing machine learning, as in the storage volume calculation unit 63b.

[0060] According to the ultrasonic measuring device 6d, for example, the seed crystal concentration in the reaction tank 1 can be estimated by determining the difference from the set value of the interface height of the phosphorus compound particle layer in the washing device 5 using ultrasonic measurement. Based on this estimation result, the withdrawal control unit 72 in Figure 1 can automatically control the seed crystal concentration in the reaction tank 1 by adjusting the amount or frequency of withdrawal of the crystallization reaction solution containing phosphorus compound particles from the reaction tank 1. Furthermore, based on the measurement result of the difference from the set value of the phosphorus compound particle interface, the seed crystal concentration in the reaction tank 1 at any given time can be estimated, and based on this seed crystal concentration, the amount of phosphorus input load of the sludge to be introduced into the reaction tank 1 can be assumed. This may also be used to correct the set value of the phosphate ion concentration in the input sludge.

[0061] By combining two or more of the above-mentioned image determination device 6b, weight measuring device 6c, and ultrasonic measuring device 6d as the measuring device 6, the amount of phosphorus compound particles stored in the cleaning device 5 can be measured with greater accuracy.

[0062] For example, the measuring device 6 may include an image determination device 6b that uses a window 51 provided in the cleaning device 5 to identify the phosphorus compound particles stored in the cleaning device 5 from the outside of the cleaning device 5, to determine the height of the interface of the phosphorus compound particle layer stored in the cleaning device 5, and a weight measuring device 6c that measures the weight of the cleaning device 5. The amount of stored phosphorus compound particles may be measured using the image determination device 6b and the weight measuring device 6c. The measuring device 6 may also include at least one of the image determination device 6b and the ultrasonic measuring device 6d, and the weight measuring device 6c.

[0063] The image determination device 6b and ultrasonic measuring device 6d, which are capable of measuring the interface height of the phosphorus compound particle layer within the washing device 5, visually or ultrasonically measure the interface height between the phosphorus compound particle layer, which contains solid phosphorus compound particles, and the supernatant water. The weight of phosphorus compound particles in the volume of the washing device 5 located below the interface height of the phosphorus compound particle layer is then calculated from the specific gravity of the phosphorus compound particles (1.7), the porosity of the layer containing phosphorus compound particles after washing and standing, the percentage of impurities present, the amount of water in the washing device 5, and the empty weight of the washing device 5.

[0064] The image determination device 6b can distinguish between the color of the normally white and transparent MAP layer and the color of plant-derived impurities such as sesame seeds, which are normally black, through image analysis. Therefore, it is possible to determine the purity of phosphorus compound particles contained in the phosphorus compound particle layer through image analysis. The weight measuring device 6c directly measures weight, so the influence of errors caused by plant-derived impurities is small. However, if the sludge contains a large amount of fine sand components such as SiO2 (specific gravity 2.0-2.2), there is a possibility that the sand components may be mistakenly identified as phosphorus compound particles. Therefore, by combining two or more of the above-mentioned image determination device 6b, weight measuring device 6c, and ultrasonic measuring device 6d as the measuring device 6, for example, the volume of the layer containing phosphorus compound particles and the layer containing impurities that settle and accumulate in the washing device 5 can be determined with a certain degree of accuracy using the image determination device 6b, and the total weight of solids in the washing device 5 can be determined accurately using the weight measuring device 6c. As a result, it becomes possible to determine the weight of the MAP more accurately by calculating the respective volumes of impurities and phosphorus compound particles and the total weight of solids.

[0065] Furthermore, by combining two or more of the above-mentioned image determination device 6b, weight measuring device 6c, and ultrasonic measuring device 6d as the measuring device 6, and performing estimations based on the following relational equations (1) to (7) that take into account the mass balance of phosphorus compound particles, the amount of phosphorus compound particles stored in the washing device 5 and the seed crystal concentration in the reaction vessel 1 can be automatically calculated.

[0066] For example, it is preferable that the calculation unit 70 in Figure 1 calculates the seed crystal concentration in the crystallization reaction solution in the reaction tank 1 containing the seed crystals based on the measurement result of the amount of phosphorus compound particles stored in the washing device 5, and that the withdrawal control unit 72 further controls at least one of the amount or frequency of withdrawal of the crystallization reaction solution from the reaction tank 1 based on the calculated seed crystal concentration. In this case, if the seed crystal concentration in the reaction tank 1 exceeds a standard range, it is also preferable to perform a treatment such as diluting the crystallization reaction solution in the reaction tank or the input sludge with dilution water.

[0067] Figure 4 is a schematic diagram showing the configuration of the crystallization reaction liquid containing phosphorus compound particles, which is drawn from the bottom of the reaction tank 1 via the drawing device 3 in Figure 1 and supplied to the separation device 4a. In the separation device 4a, separated sludge is separated from the crystallization reaction liquid. The separated sludge is supplied to the sludge treatment. The remaining crystallization reaction liquid containing phosphorus compound particles is introduced into the washing device 5. In the washing device 5, the phosphorus compound particles can be classified into those that leak out of the washing device 5 during the washing process described above (hereinafter referred to as "MAP leak"), impurities w2 that are stored in the washing device 5, and phosphorus compound particles that are separated from the sludge by the washing process in the washing device 5 and transferred to the subsequent drying equipment (hereinafter referred to as "pure MAP w1"). The total weight wo of the solids stored in the washing device 5 is the sum of pure MAP w1 and impurities w2.

[0068] Taking into account the mass balance within reaction vessel 1, separation device 4a, and washing device 5 in Figure 1, the weight W [kg - pure MAP] of the pure MAP withdrawn from reaction vessel 1 can be calculated using the following relation (1). W = Q × T × C × R / 100 ... (1) Here, W: weight of pure MAP withdrawn from reaction vessel 1 [kg - pure MAP] Q: What is the withdrawal rate of the crystallization reaction solution containing MAP withdrawn from reaction vessel 1? [m³] 3 -Crystallized reaction solution / minute] T: Withdrawal time [minutes] for the crystallization reaction solution containing MAP withdrawn from reaction vessel 1. C: Pure MAP concentration in reaction vessel 1 [kg - pure MAP / m³] 3 -Crystallization reaction solution] R: MAP recovery rate of separation device 4a and washing device 5 [%]

[0069] Here, let v1 be the volume of pure MAP w1 introduced into the washing device 5, v2 be the volume of impurities w2, and v0 be the total volume of solids, which is the sum of the volume of pure MAP wt stored in the washing device v1 and the volume of impurities w2 v2. If ρ1 is the density of pure MAP and ρ2 is the density of impurities, then the weight wM when the total volume of solids v0 is 100% pure MAP is: wM = v0 × ρ1 ... (2) This is the result.

[0070] If we let w0 be the weight of the total volume v0 of the actual solid material, then the weight difference w3 caused by impurities entering the washing device 5 is: w3 = wM - w0 ... (3) This is the result. Since the difference ρ3 between the pure MAP and the impurity density is ρ1 - ρ2, the capacity v2 of the impurity w2 is v2 = w3 / ρ3 ... (4) This is the result.

[0071] Therefore, the weight w1 of the pure MAP that is fed into the washing device 5 is w1 = (v0 - v2) × ρ1 ={v0-(w3 / ρ3)}×ρ1 =[v0-{(wM-w0) / (ρ1-ρ2)}]×ρ1 =[v0-{(v0×ρ1-w0) / (ρ1-ρ2)}]×ρ1···(5) This is the result.

[0072] Also, the weight of impurity w2 is, w2 = w0 - w1 ... (6) This is the result.

[0073] Furthermore, the concentration C of the pure MAP produced in reaction vessel 1 can be expressed by relational equations (1) and (5). C=[V0-{(v0×ρ1-w0) / (ρ1-ρ2)}]×ρ1÷(Q×T×R / 100) ···(7) This is the result.

[0074] The total volume v0 of solid matter in the washing device 5 can be automatically measured by measuring the height of the interface between the impurity layer or the phosphorus compound particle layer using the image determination device 6b or the ultrasonic measuring device 6d. The total weight wo in the washing device 5 can be automatically measured using the weight measuring device 6c. By using measured values ​​for the density ρ1 of pure MAP, the density ρ2 of impurities, and the recovery rate R, the weight w1 of pure MAP introduced into the washing device 5 and the concentration C of pure MAP produced in the reaction vessel 1 can be calculated.

[0075] According to this embodiment, the weight w1 or volume v1 of the pure MAP stored in the washing device 5 is calculated based on the material balance relational equations (1) to (7), and based on this calculation result, the transfer control unit 74 adjusts at least one of the amount or frequency of transfer of pure MAP from the washing device 5. For example, if the calculated weight w1 of the pure MAP is greater than the set value, the transfer control unit 74 controls the transfer to increase the amount of pure MAP transferred from the washing device 5 by the transfer device 8 per transfer or to increase the transfer frequency (number of transfers) in proportion to the increase. If the calculated weight w1 of the pure MAP is less than or equal to the set value, the transfer control unit 74 controls the amount of pure MAP transferred from the washing device 5 by the transfer device 8 per transfer or to decrease the transfer frequency. This provides a method and system for producing phosphorus compounds that can efficiently transfer phosphorus compounds from the washing device 5.

[0076] (Other embodiments) Although the present invention has been described by the embodiments described above, the descriptions and drawings that constitute part of this disclosure should not be understood as limiting the invention. Various alternative embodiments and operational techniques can be implemented from this disclosure by those skilled in the art. [Explanation of Symbols]

[0077] 1…Reaction vessel 2… Drug supply device 3… Extraction device 4, 4a, 4b…separation device 5…Washing device 6… Measuring device 6b...Image determination device 6c…Weight measuring device 6d... Ultrasonic measuring device 7...Control device 8…Transfer device 10... Sludge supply device 11, 12...pH meter 31... Pump 50... Washing tank 51... Window section 53, 54... Piping 60b... Processing Unit 61b...Photography Department 61c...Weight measurement section 61d... Ultrasound Diagnostic Department 62b...Image determination unit 63b...Storage volume calculation unit 63c...Storage volume calculation unit 63d...Storage volume calculation unit 64b...Learning Department 70...Arithmetic section 71…Drug supply control unit 72... Extraction Control Unit 73… Cleaning Control Unit 74...Transfer control unit 75…Learning Department

Claims

1. By introducing phosphorus-containing sludge into a reaction tank containing a crystallization reaction solution using seed crystals of phosphorus compounds and mixing it, phosphorus compound particles are crystallized in the crystallization reaction solution. The crystallization reaction solution containing the phosphorus compound particles is withdrawn from the reaction vessel. The phosphorus compound particles are recovered from the crystallization reaction solution, stored in a washing device, and washed. The amount of phosphorus compound particles stored in the washing device is measured. A method for producing a phosphorus compound, comprising controlling at least one of the amount or frequency of transfer of the phosphorus compound particles when transferring the washed phosphorus compound particles outside the washing device, based on the measurement results of the amount of stored phosphorus compound particles.

2. A method for producing a phosphorus compound according to claim 1, comprising determining the amount of phosphorus compound particles stored by acquiring image data of the height of the interface of the phosphorus compound particle layer, which is identified from outside the washing device through a window provided in the washing device, and performing image determination on the image data.

3. A method for producing a phosphorus compound according to claim 1, comprising measuring the amount of phosphorus compound particles stored in the washing device by measuring the weight of the washing device.

4. A method for producing a phosphorus compound according to claim 1, comprising measuring the amount of phosphorus compound particles stored in the washing device by measuring the height of the interface of the phosphorus compound particle layer stored in the washing device using an ultrasonic measuring device.

5. A method for producing a phosphorus compound according to claim 1, comprising inputting image data of the height of the interface of the phosphorus compound particle layer to be measured into a model constructed by a machine learning algorithm that uses training data including feature quantities obtained from image data of the height of the interface of the phosphorus compound particle layer to be measured, which is identified from outside the washing device through a window provided in the washing device, and feature quantities representing the amount of the phosphorus compound particles stored in the washing device associated with the image data, and outputting a predicted value of the amount of the phosphorus compound particles to be measured, thereby measuring the amount of the phosphorus compound particles stored.

6. A method for producing a phosphorus compound according to claim 5, further comprising: the learning data including at least a feature quantity indicating at least one of a suitable transport amount or transport frequency for transporting the phosphorus compound particles, associated with image data of the height of the interface of the phosphorus compound particle layer; and inputting image data of the height of the interface of the phosphorus compound particle layer to be measured into the model to output at least one of the suitable transport amount or transport frequency for the phosphorus compound particles.

7. Based on the measurement results of the amount of phosphorus compound particles stored in the washing device, the concentration of seed crystals in the crystallization reaction solution in the reaction vessel containing the seed crystals is calculated. A method for producing a phosphorus compound according to any one of claims 1 to 6, further comprising controlling at least one of the amount or frequency of withdrawal of the crystallization reaction solution from the reaction vessel based on the calculation result of the seed crystal concentration.

8. A reaction tank for generating phosphorus compound particles from phosphorus-containing sludge using a crystallization reaction with seed crystals of phosphorus compounds, A withdrawal device for withdrawing the crystallization reaction solution containing the phosphorus compound particles from the reaction vessel, A separation device for separating the phosphorus compound particles from the crystallization reaction solution extracted by the extraction device, A washing device for washing the phosphorus compound particles separated by the separation device, A transfer device for transferring the phosphorus compound particles inside the washing device to the outside of the washing device, A measuring device for measuring the amount of phosphorus compound particles stored in the washing device, Based on the measurement results of the amount of phosphorus compound particles stored in the washing device, a transfer control unit controls at least one of the amount or frequency of transfer of the phosphorus compound particles when transferring them from the washing device to the outside of the washing device. A phosphorus compound production system equipped with the following features.

9. A reaction tank for generating phosphorus compound particles from phosphorus-containing sludge using a crystallization reaction with seed crystals of phosphorus compounds, A withdrawal device for withdrawing the crystallization reaction solution containing the phosphorus compound particles from the reaction vessel, A separation device for separating the phosphorus compound particles from the crystallization reaction solution extracted by the extraction device, A washing device for washing the phosphorus compound particles separated by the separation device, A transfer device for transferring the phosphorus compound particles inside the washing device to the outside of the washing device, A measuring device for measuring the amount of phosphorus compound particles stored in the washing device, Based on the measurement results of the amount of phosphorus compound particles stored in the washing device, the concentration of seed crystals in the crystallization reaction solution in the reaction vessel containing the seed crystals is calculated. An extraction control unit controls at least one of the amount or frequency of extraction of the crystallization reaction solution from the reaction vessel based on the calculation result of the seed crystal concentration. A phosphorus compound production system equipped with the following features.

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