JP2019107588A - Method for operation of phosphorus recovery device - Google Patents

Abstract

To provide a method for operation of a phosphorus recovery device which can prevent abnormal crystal growth of phosphorus to a seed crystal.SOLUTION: A method for operation of a phosphorus recovery device which comprises a crystallization column body 1, and in which a lower space 11 is formed at a lower part of the crystallization column body 1, a seed crystal support net 12 is detachably provided at an upper part of the lower space 11, and a seed crystal filling part 13 is formed at an upper part of the seed crystal support net 12. According to this method, when raw water containing phosphorus and circulation water are fed to the seed crystal filling part 13 and the seed crystal filling part 13 is forcibly agitated at a prescribed interval by use of circulation water, a quantity of said agitation water is adjusted to a range of 1.5 to 3 times of a quantity of said circulation water.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a phosphorus recovery apparatus using seed crystals, and more particularly, to a phosphorus recovery apparatus capable of preventing crystallization between seed crystals.

  A crystallization method is known as an apparatus for dephosphorizing phosphorus from raw water containing phosphorus to recover phosphorus, and a fluidized bed in which phosphorus in raw water is crystallized on the surface of seed crystals as hydroxyapatite to recover phosphorus. Formula crystallization dephosphorization methods are known.

JP, 2005-95726, A

  Patent Document 1 introduces phosphorus-containing raw water from a pressure chamber provided in the lower part of a reaction vessel toward a fluidized bed in the upper part of the pressure chamber, and in this fluidized bed, seed crystals containing calcium phosphate and phosphorus in the raw water. Disclose a method of bringing

  In the apparatus shown in FIG. 1 of Patent Document 1, a bottom plate is formed by a flat partition plate, raw water is introduced from a raw water pressure chamber through a blowout nozzle and a distributor into a fluidized bed, circulating water is introduced into a circulating water pressure chamber, a distributor Once introduced into the fluidised bed, both waters are designed to mix only in the fluid phase seed.

However, even if it is intended to eject raw water at the distributor, since it spouts linearly into the seed crystals, there will be portions where the raw water and the seed crystals do not contact in the fluidized bed, and portions where the seed crystals do not partially fluidize Will occur.
As a result, agglomeration of the seed crystals occurs, resulting in large hard lumps, the contact area of the seed crystals with the raw water decreases, and the phosphorus recovery efficiency decreases.

  Therefore, an object of the present invention is to provide a method of operating a phosphorus recovery apparatus that can prevent abnormal crystal growth of phosphorus on seed crystals.

  Further, other objects of the present invention will become clear by the following description.

  The above problems are solved by the following inventions.

(Claim 1)
A crystallization column main body is provided, and a lower space is formed in the lower portion of the crystallization tower main body, and a seed crystal support net is detachably provided in the upper portion of the lower space, and is provided above the seed crystal support net In the method of operating the phosphorus recovery apparatus, wherein the seed crystal filling portion is formed,
The raw water containing phosphorus and the circulating water are supplied to the seed crystal filling unit, and the seed crystal filling unit is forcibly stirred at predetermined intervals using stirring water,
A method of operating a phosphorus recovery device, wherein the amount of the stirred water is adjusted to a range of 1.5 to 3 times the amount of the circulating water.
(Claim 2)
Supplying phosphorus-containing raw water to the lower space;
Raw water containing phosphorus is supplied as an upward flow from the lower part of the seed crystal filling part provided at the upper part of the lower space, upward
The phosphorus in the raw water is crystallized on the surface of seed crystals and recovered,
The treated water from which phosphorus has been removed is taken out from the top of the crystallizer body,
A part of the treated water taken out is stored in the circulation tank,
The circulating water in the circulation tank is circulated and transferred to the seed crystal filling unit, and the seed crystal packing unit is forcibly stirred at predetermined intervals using the stirring water in the circulation and transfer process. The operating method of the phosphorus collection | recovery apparatus of Claim 1.
(Claim 3)
A phosphorus concentration meter for measuring the phosphorus concentration of the raw water is provided at any position until the raw water is supplied to the lower space,
The control unit is configured to execute stirring processing based on the phosphorus concentration measured by the phosphorus concentration meter, and a storage unit in which “concentration-stirring interval” information in which the phosphorus concentration and the stirring interval are associated in advance is stored.
When forcibly stirring the seed crystal filling portion at predetermined intervals,
When the phosphorus concentration measured by the phosphorus concentration meter is input, the control unit determines the stirring interval with reference to the "concentration-stirring interval" information,
Generating a stirring process signal based on the determined stirring interval;
The operating method of the phosphorus recovery device according to claim 1 or 2, wherein the stirring process is performed based on the stirring process signal.
(Claim 4)
The measurement by the phosphorus concentration meter is performed once at a predetermined time,
The control unit calculates the degree of change between the phosphorus concentration measured before the predetermined time has elapsed and the phosphorus concentration measured after the predetermined time has elapsed;
It is determined whether the calculated degree of change exceeds a predetermined value,
If the calculated degree of change exceeds a predetermined value, the stirring interval is corrected based on a correction value corresponding to the degree of change,
The method for operating a phosphorus recovery device according to claim 3, wherein a stirring process signal is generated based on the corrected stirring interval.
(Claim 5)
The method according to claim 4, wherein the storage unit stores “change degree-correction value” information in which a correction value based on the change degree is associated.

  According to the present invention, it is possible to provide a method of operating a phosphorus recovery apparatus capable of preventing abnormal crystal growth of phosphorus on seed crystals.

Schematic explanatory drawing which shows an example of the phosphorus collection | recovery apparatus applicable to this invention Flow chart showing an example of the operation method of the phosphorus recovery device of the present invention Figure showing an example of "concentration-stirring interval" information of the present invention Flow chart showing an example of the stirring process of the operation method of the present invention Flow chart showing another example of the stirring process of the operation method of the present invention A diagram showing an example of the “degree of change-correction value” information of the present invention

  Hereinafter, embodiments of the present invention will be described based on the drawings.

FIG. 1 is a schematic explanatory view showing an example of the operation method of the phosphorus recovery apparatus of the present invention. In the figure, reference numeral 1 denotes a cylindrical crucible type crystal body. Although the upper part of the crystallization tower main body 1 may be provided with an openable and closable lid, the open state is maintained from the viewpoint of easiness of operation management, simplification of the apparatus and cost reduction. preferable.
A lower space 11 sealed by a curved end plate 10 is formed in the lower part of the crystallizer main body 1.

  Fixing of the lower portion of the crystallizer main body 1 and the end plate 10 is not particularly limited, but examples include fixing by welding, fixing by a flange, and the like.

  In FIG. 1, reference numeral 12 denotes a seed crystal support net provided on the upper part of the lower space 11, and is detachably and horizontally mounted on a fixed part (not shown). The size of the network of the seed crystal supporting mesh 12 is preferably such that the seed crystals do not fall.

  A seed filling portion 13 is formed on the top of the seed support network 12. For the seed crystal filling portion 13, seed crystals containing calcium silicate hydrate are used.

  Phosphorus in the raw water, when passing through the seed filling portion 13, crystallizes on the surface of the seed as hydroxyapatite. Phosphorus in the raw water is removed and recovered by this crystallization reaction. When removing phosphorus in raw water, pH adjustment and addition of calcium can be performed as needed.

  Denoted at 14 is a raw water discharge port, which is provided at the upper part of the lower space 11 and at the lower part of the seed crystal support net 12. The raw water discharge port 14 is directed downward to be positioned toward the end plate 10.

  The raw water discharged from the raw water discharge port 14 is discharged downward as pressure water toward the end plate 10, and as a result, collides with the end plate 10 to be a reverse flow (reflected flow) and to be an upward flow.

  In the present invention, since the upflow has a pressure to flow the seed crystals of the seed filling portion 13, the pressure enables the seed crystals to flow. That is, a fluidized bed of seed crystals is formed.

  In order to apply a pressure sufficient to flow the seed crystals of the seed crystal filling unit 13 to the upward flow, the pressure of the raw water supplied to the raw water discharge port 14 needs to be a predetermined pressure or more. At that time, it is necessary to consider various pressure drops, for example, the pressure drop required for the formation of the reflection flow, and the pressure drop for flowing the seed crystals of the seed filling portion 13.

  In the present invention, since the upflow as described above is formed, it is possible to prevent the growth of abnormal crystals of seed crystals. That is, crystallization of the seed crystals can be prevented.

  In the embodiment shown in FIG. 1, the raw water pipe 15 is provided in the vicinity of the central portion of the cross section of the crystallizer body 1 so as to extend downward from the top of the crystallizer body 1 and is connected to the raw water discharge port 14.

  As a result of being configured as described above, when the raw water containing phosphorus is introduced from the raw water pump 16 into the raw water pipe 15 at a predetermined pressure, it reaches the discharge port 14 of the raw water.

In a preferred embodiment of the present invention, when the raw water piping 15 is made to penetrate the center of the seed crystal filling portion 13, seed crystals may adhere around the piping, and the adhered seed crystals become lumps. Sometimes grow.
Raw water discharged from the raw water discharge port 14 at a predetermined pressure collides with the end plate 10 and becomes a reverse flow (reflected flow), and an upward flow formed at the predetermined pressure extends in the cross-sectional direction across the inside of the crystallizer body 1 It will be an equal upward flow.
The rising flow rises while sliding around the pipe, so that no seed crystals adhere to the pipe and no adhesion growth occurs.

  According to the present invention, lump formation between seed crystals can be prevented by the upward flow formed by the predetermined pressure.

  Furthermore, the reflected flow from the curved surface of the mirror plate is ejected from the seed crystal support network 12 to enable uniform stirring, and as a result, an upward flow is uniformly formed in the crystallizer main body 1. This can prevent abnormal crystal growth.

  In a preferred embodiment of the present invention, the upper part of the crystallizer body 1 is released, phosphorus is removed from the raw water by the crystallization reaction, and the treated water obtained is the upper end 17 of the wall of the crystallizer body 1. The structure which overflows and overflows is adopted.

As illustrated, a portion of the treated water overflowed by overflowing the upper end 17 of the wall surface of the crystallizer body 1 is extracted, and a portion of the extracted treated water is stored in the circulation tank 19.
Circulating water is circulated and supplied to the seed crystal filling unit 13 so as to be returned from the circulation tank 19 to the raw water pipe 15 using the circulation pump 20.

  In the present embodiment, it is preferable that an outlet 18 be provided in the vicinity of the central lower portion of the end plate 10. The seed crystals may flow and collide with one another to be crushed or worn, and the crushed particles and the like may fall downward from the seed crystal support network 12 and deposit on the upper surface of the mirror plate 10. In that case, since the deposition place is a curved mirror surface, it tends to gather near the center lower part of the mirror plate 10. Since the discharge port 18 is provided in the vicinity of the central lower portion of the end plate 10 that collects easily, the seed crystals deposited on the end plate 10 can be reliably discharged to the outside.

The circulating water in the circulation tank 19 is circulated and transferred to the seed crystal filling unit 13 by the circulation pump 20. In the circulation and transfer process, the seed crystal filling unit 13 is forcibly stirred at predetermined intervals.
That is, in the process of supplying the circulating water in the circulating tank 19 to the seed crystal filling portion 13, the water amount of the stirring water is in the range of 1.5 to 3 times the water amount of the circulating water only during the time of forced stirring. Set Thereby, at the time of normal operation, the discharge amount of the circulation pump 20 can be reduced to the range of 0.3 to 0.7 times at the time of normal operation, and this reduction can reduce the circulation cost.
In addition, the amount of water of the stirring water which stirs forcibly is preferable in the range of 2 times-2.5 times. This makes it possible to further optimize the operating cost.

The present invention is characterized in that the seed crystal filling portion 13 is forcibly stirred at predetermined intervals using stirring water. This forced stirring can prevent abnormal crystal growth of phosphorus on seed crystals.
As a preferred embodiment of the present invention, a stirring pump is provided to supply stirring water capable of stirring the seed crystal packed portion 13 in the crystallization column main body 1. As the stirring water, the treated water in the circulation tank 19 can be used. In the present invention, it is also preferable to further provide a stirring blower 22 for supplying the stirring air. With this configuration, stirring water or stirring air is sent to the lower space 11 of the crystallizer main body 1, and stirring water or stirring air is sent to the seed crystal filling unit 13 to promote the prevention of abnormal crystal growth of phosphorus to the seed crystals. can do.
Stirring water may be supplied by using the stirring pump 21 and the circulation pump 20 in combination, or may be supplied by the stirring pump 21 alone.

  In the present invention, the phosphorus concentration meter 23 for measuring the phosphorus concentration of the raw water is provided at any position until the raw water is supplied to the lower space 11 when the seed crystal filling portion 13 is forcibly stirred. preferable.

In the present invention, it is preferable to provide a control unit 30 that executes a stirring process based on the phosphorus concentration measured by the phosphorus concentration meter 23.
Further, in the present invention, it is preferable to provide a storage unit 31 in which “concentration-stirring interval” information in which the phosphorus concentration and the stirring interval are associated in advance as shown in FIG. 3 is stored.

Next, the operation method of the phosphorus recovery apparatus of the present invention will be specifically described.
As a preferable discharge amount of circulating water according to the present invention, assuming that the discharge amount of the circulation pump 20 is q1 and the discharge amount in the conventional normal operation is Q, the discharge amount ratio is the discharge amount q1 of the discharge amount Q It is operated by reducing it to the range of 0.3 to 0.7 times. And when forcedly stirring and setting it as the discharge amount q2 of stirring water, the discharge amount q2 is operated in 1.5 to 3 times the discharge amount q1. The flow of the stirring process at the time of forcedly stirring will be described with reference to FIGS.

FIG. 2: is a figure which shows an example of the processing flow of the operating method of the phosphorus collection | recovery apparatus of this invention.
As shown in FIG. 2, first, the phosphorus concentration of the raw water containing phosphorus is measured by a phosphorus concentration meter 23 (S10).

  Next, the control unit 30 generates a stirring process signal (S11). Hereinafter, generation of the stirring process signal will be described.

An example of the process of agitation processing signal generation will be described with reference to FIG.
As shown in FIG. 2, first, when the phosphorus concentration measured by the phosphorus concentration meter 23 is input (S110), the control unit 30 stores the “concentration-agitation interval” shown in FIG. 3 stored in the storage unit 31. With reference to the information (S111), the stirring interval is determined based on the input phosphorus concentration (S112).
For example, when the phosphorus concentration measured by the phosphorus concentration meter 23 is 30 mg / L, it corresponds to "20 or more and less than 35" of "No. 3" when referring to the "concentration-stirring interval" information. And "8" which is a stirring interval of "No. 3" is determined.

Next, based on the determined stirring interval, a stirring process signal is generated (S113).
For example, as described above, when the stirring interval is determined to be “8”, a signal is generated to execute the stirring process with the stirring water once every eight hours. In this case, a timer or the like (not shown) may be provided to generate an agitation processing signal for transmitting a total of three times every eight hours, or to transmit an agitation processing signal driven three times every eight hours once. It may be generated. The stirring process can be performed by setting the processing time of the stirring process to a predetermined time in advance by the control unit 30.

  When the stirring process signal is generated, the process returns to the process flow shown in FIG. 2, and the stirring process signal is transmitted (S12). Specifically, the above-mentioned stirring process signal is transmitted to cause the stirring pump 21 and the stirring blower 22 to execute the stirring process for a predetermined time. In this case, when the above-described discharge amount q2 of the stirring water and the discharge amount q1 of the circulating water are used as the stirring pump 21, the discharge amount q2-q1 is supplied. That is, the discharge amount q2 of the stirring water is the sum of the amounts of water supplied by the circulation pump 20 and the stirring pump 21. Further, when performing the stirring process, the stirring blower 22 may supply the stirring air.

  As a result, the stirring pump 21 that has received the stirring processing signal executes the stirring processing based on the stirring processing signal, and the upward flow is formed. As a result, by the stirring process, the discharge amount q2 of the stirring water at the time of stirring is supplied, and the amount of water is increased from the discharge amount q1 of the circulating water at the normal operation to form rising flow. It can be prevented from growing in bulk.

  In addition, since the discharge amount q2 of the stirring water is supplied for a predetermined time and forcedly stirred, the discharge amount q1 of the circulation pump 20 during normal operation other than the predetermined time to be forcibly stirred is It is possible to drive with reduced output. As a result, the operating cost of the phosphorus recovery device can be reduced.

FIG. 5 is a flow chart showing another example of agitation processing signal generation (agitation processing signal generation (II)).
In this embodiment, the storage unit 31 may store a predetermined value for the stirring process when the degree of change is large, and may store a correction value for correcting the stirring interval when the predetermined value is exceeded. Also, as shown in FIG. 6, “variation degree-correction value” information in which the degree of variation is associated with the correction value may be stored. The degree of change will be described later.

  First, when the phosphorus concentration measured by the phosphorus concentration meter 23 is input (S110), the control unit 30 refers to “concentration-stirring interval” information stored in the storage unit 31 (S111), and is input Based on the determined phosphorus concentration, the stirring interval is determined (S112).

Next, the density change degree is calculated (S200). For example, when the measurement interval of the phosphorus concentration meter 23 is once a day, the control unit 30 can cause the storage unit 31 to continuously store the measurement result of the phosphorus concentration. The measurement interval can be set by the control unit 30. Then, in this case, the degree of change between the measured phosphorus concentration and the phosphorus concentration measured on the previous day is calculated.
That is, the measurement by the phosphorus concentration meter 23 is performed once at a predetermined time, and the control unit 30 calculates the degree of change between the phosphorus concentration measured before the predetermined time has elapsed and the phosphorus concentration measured at the predetermined time.

Next, the control unit 30 determines whether the degree of change exceeds a predetermined value (S201).
If it exceeds the predetermined value (YES in S201), the "degree of change-correction value" information is referred to (S202), a correction value is determined, and the stirring interval determined in S112 is determined based on the correction value. It corrects (S203).

  Next, based on the corrected stirring interval, a stirring process signal is generated (S113).

  On the other hand, when the predetermined value is not exceeded (NO in S201), a stirring process signal is generated based on the stirring interval determined in S112 (S113).

  Thereby, abnormal crystal growth can be prevented even when the phosphorus concentration changes rapidly.

  An example is concretely demonstrated based on the flowchart of FIG. The correction value of the “degree of change-correction value” information shown in FIG. 6 is a correction value for correcting “No.” in FIG. 3.

  In the illustrated example, it is assumed that the measured phosphorus concentration is 52 mg / L and the measured phosphorus concentration on the previous day is 30 mg / L, and the storage unit stores a predetermined value of 20.

  In this case, when the measured phosphorus concentration of 53 mg / L is input first, referring to the "concentration-stirring interval" information in FIG. 2, the phosphorus concentration of "No. 5" corresponds to "45 or more and less than 55". "5" which is the stirring interval corresponding to this is determined.

Next, when the degree of change is calculated, the degree of change is 52-30 = 22. When the degree of change is 22, it exceeds 20 which is a predetermined value. In this case, with reference to the "degree of change-correction value" information, the correction value "+1" is determined. Then, “No. 5” is corrected to “No. 6” by being “+1”. That is, the stirring interval "5" corresponding to "No. 5" is corrected to the stirring interval "4" corresponding to "No. 6".
As a result, the stirring interval is corrected such that the stirring process is performed once in "5" hours and once in "4" hours.

  In the above description, the correction value for “No.” has been described, but it may be a correction value for correcting the stirring interval. Although the correction value has been described only in the case of “+1”, the present invention is not limited to this, and the value of the correction value may be changed when the degree of change sharply increases. Specifically, the above-described predetermined value may be set as a first predetermined value, a second predetermined value different from the first predetermined value may be provided, and a correction value corresponding to this may be provided.

  In addition, the control unit 30 continuously stores the phosphorus concentration measured at a predetermined measurement interval of the phosphorus concentration meter 23 in the storage unit 31 so that the information on the fluctuation of the continuous phosphorus concentration can be obtained by the driving manager or the like. It is also possible to prompt the setting of the correction value or the predetermined value.

  As a result, even if the phosphorus concentration is rapidly increased, abnormal crystal growth can be prevented, and appropriate operation can be realized according to the rapid change in phosphorus concentration, thus reducing extra operation costs. Can.

1: Crystallizer body 10: End plate 11: Lower space 12: Seed crystal support network 13: Seed crystal packing part 14: Discharge port 15: Raw water piping 16: Raw water pump 17: Upper part 18: Discharge port 19: Circulation tank 20: Circulating pump 21: stirring pump 22: stirring blower 23: phosphorus concentration meter 30: control unit 31: storage unit

Claims (5)

A crystallization column main body is provided, and a lower space is formed in the lower portion of the crystallization tower main body, and a seed crystal support net is detachably provided in the upper portion of the lower space, and is provided above the seed crystal support net In the method of operating the phosphorus recovery apparatus, wherein the seed crystal filling portion is formed,
The raw water containing phosphorus and the circulating water are supplied to the seed crystal filling unit, and the seed crystal filling unit is forcibly stirred at predetermined intervals using stirring water.
A method of operating a phosphorus recovery device, wherein the amount of the stirred water is adjusted to a range of 1.5 to 3 times the amount of the circulating water. Supplying phosphorus-containing raw water to the lower space;
Raw water containing phosphorus is supplied as an upward flow from the lower part of the seed crystal filling part provided at the upper part of the lower space, upward
The phosphorus in the raw water is crystallized on the surface of seed crystals and recovered,
The treated water from which phosphorus has been removed is taken out from the top of the crystallizer body,
A part of the treated water taken out is stored in the circulation tank,
The circulating water in the circulation tank is circulated and transferred to the seed crystal filling unit, and the seed crystal packing unit is forcibly stirred at predetermined intervals using the stirring water in the circulation and transfer process. The operating method of the phosphorus collection | recovery apparatus of Claim 1. A phosphorus concentration meter for measuring the phosphorus concentration of the raw water is provided at any position until the raw water is supplied to the lower space,
The control unit is configured to execute stirring processing based on the phosphorus concentration measured by the phosphorus concentration meter, and a storage unit in which “concentration-stirring interval” information in which the phosphorus concentration and the stirring interval are associated in advance is stored.
When forcibly stirring the seed crystal filling portion at predetermined intervals,
When the phosphorus concentration measured by the phosphorus concentration meter is input, the control unit determines the stirring interval with reference to the "concentration-stirring interval" information,
Generating a stirring process signal based on the determined stirring interval;
The operating method of the phosphorus recovery device according to claim 1 or 2, wherein the stirring process is performed based on the stirring process signal. The measurement by the phosphorus concentration meter is performed once at a predetermined time,
The control unit calculates the degree of change between the phosphorus concentration measured before the predetermined time has elapsed and the phosphorus concentration measured after the predetermined time has elapsed;
It is determined whether the calculated degree of change exceeds a predetermined value,
If the calculated degree of change exceeds a predetermined value, the stirring interval is corrected based on a correction value corresponding to the degree of change,
The method for operating a phosphorus recovery device according to claim 3, wherein a stirring process signal is generated based on the corrected stirring interval. The method according to claim 4, wherein the storage unit stores “change degree-correction value” information in which a correction value based on the change degree is associated.

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